G2Cdb::Gene report

Gene id
Gene symbol
Homo sapiens
v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog
G00001294 (Mus musculus)

Databases (7)

ENSG00000133703 (Ensembl human gene)
3845 (Entrez Gene)
271 (G2Cdb plasticity & disease)
KRAS (GeneCards)
190070 (OMIM)
Marker Symbol
HGNC:6407 (HGNC)
Protein Sequence
P01116 (UniProt)

Synonyms (1)

  • KRAS1

Literature (519)

Pubmed - human_disease

  • PTPN11, RAS and FLT3 mutations in childhood acute lymphoblastic leukemia.

    Yamamoto T, Isomura M, Xu Y, Liang J, Yagasaki H, Kamachi Y, Kudo K, Kiyoi H, Naoe T and Kojma S

    Departments of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan. tomotomo@med.nagoya-u.ac.jp

    PTPN11, the gene which encodes protein tyrosine phosphatase SHP-2, plays an important role in regulating intracellular signaling. Germline mutations in PTPN11 were first observed in Noonan syndrome, while somatic mutations were identified in hematological myeloid malignancies. Recently, PTPN11 mutations have been reported in children with acute lymphoblastic leukemia (ALL). In the present study, we investigated the prevalence of mutations in PTPN11, RAS and FLT3 in samples from 95 Japanese children with ALL. We observed exon 3 and 8 missense mutations of PTPN11 in 6 children with B precursor ALL. One patient with Down syndrome and ALL had PTPN11 mutation. We also identified RAS mutations in ten patients and FLT3 internal tandem duplication (FLT3/ITD) in one patient. None of the patients had simultaneous mutations in PTPN11 and RAS, while one patient had both PTPN11 and FLT3 mutations. These data suggest that PTPN11 mutation may play an important role for leukemogenesis in a proportion of children with ALL, particularly B precursor ALL.

    Leukemia research 2006;30;9;1085-9

Pubmed - other

  • MDR1 polymorphism role in patients treated with cetuximab and irinotecan in irinotecan refractory colorectal cancer.

    Paule B, Castagne V, Picard V, Saffroy R, Adam R, Guettier C, Farinotti R and Bonhomme-Faivre L

    Centre Hépatobiliaire, Department of Pharmacy-Pharmacology, Paul Brousse University Hospital, AP-HP, 12-14, avenue Paul Vaillant-Couturier, Villejuif, France.

    The aim of the study was to evaluate the influence of the MDR1 C3435T polymorphism on the therapeutic response in 23 patients treated with cetuximab plus irinotecan for irinotecan refractory liver metastatic colorectal cancer considering their KRAS status. Indeed, irinotecan and its active metabolite (SN-38) are both substrates of P-glycoprotein (P-gp) encoded by MDR1. Patients received cetuximab and irinotecan up to progression. The overall survival was 55% at 10 months. Overall, four patients had an undetermined KRAS status and two patients with mutated KRAS were in progression disease. The response to treatment was observed after 3 months among the 17 wild-type KRAS patients. Two patients presented a progressive disease (1 TT and 1 CT), eight patients had a stable disease (5 CC and 3CT) and five patients had a partial response (3 CC and 2 CT). Importantly, 2 patients (2 TT) were in complete response and still alive 5 years after starting the treatment, which suggests that the combination of wild-type KRAS and MDR1 3435 TT may be a factor of good prognosis. These results suggest that EGFR inhibition by cetuximab may overcome this irinotecan resistance by abrogating drug efflux depending on MDR1 3435 polymorphism. Among patients resistant to irinotecan, it is still possible to use the association of cetuximab plus irinotecan to obtain a complete resection of hepatic metastases that is necessary to improve their survival.

    Medical oncology (Northwood, London, England) 2010;27;4;1066-72

  • KRAS status in patients with colorectal cancer peritoneal carcinomatosis and its impact on outcome.

    Gillern SM, Chua TC, Stojadinovic A and Esquivel J

    Department of Surgery, Walter Reed Army Medical Center, United States Military Cancer Institute, Washington, DC, USA.

    Background: KRAS mutated colorectal cancers (CRC) are reported to be associated with a poor response to anti-EGFR monoclonal antibody therapy and poor prognosis. We studied the rates of KRAS mutated tumors in patients with peritoneal carcinomatosis from CRC and investigated the association of KRAS status with specific clinicopathologic factors.

    Methods: A retrospective observational study of tumor specimens from 23 patients with peritoneal carcinomatosis from CRC was performed using standard genomic DNA sampling techniques to identify KRAS mutations. Correlation between clinicopathologic factors and KRAS mutation status was performed using the Fisher exact test or χ test, as appropriate.

    Results: Eleven (48%) of 23 patients had KRAS mutations. There were no statistically significant correlations in patient demographics, tumor pathology, surgical evaluation, treatments, or survival outcomes for peritoneal carcinomatosis between patients with KRAS mutations or wild-type KRAS status.

    Conclusion: The prevalence of KRAS mutation in CRC patients with peritoneal carcinomatosis is 48% in this preliminary study and clinicopathologic factors appear to be independent of mutation status.

    American journal of clinical oncology 2010;33;5;456-60

  • KRAS mutations and resistance to EGFR-TKIs treatment in patients with non-small cell lung cancer: a meta-analysis of 22 studies.

    Mao C, Qiu LX, Liao RY, Du FB, Ding H, Yang WC, Li J and Chen Q

    Department of Epidemiology, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, China.

    Epidemiologic studies have evaluated the association between KRAS mutations and resistance to the treatment of epidermal growth factor receptor (EGFR) tyrosine-kinase inhibitors (TKIs) in patients with non-small cell lung cancer (NSCLC). However, results were inconclusive. To derive a more precise estimation of the relationship, we performed this meta-analysis. Systematic computerized searches of the PubMed and Medline databases (up to Jun 30, 2009) were performed. A total of 22 studies were included in the final meta-analysis, consisting of 1470 NSCLC patients, of whom 231 had KRAS mutations (16%). Current or former smokers had a higher frequency of KRAS mutations than never smokers (25% versus 6%; OR=4.36; P<0.01). Mutations were more common among adenocarcinoma than other histologies (26% versus 16%; OR=1.98; P<0.01). The objective response rate (ORR) of NSCLC patients with mutant KRAS was 3% (6/210), whereas the ORR of NSCLC patients with wild-type KRAS was 26% (287/1125). The overall pooled RR for ORR was 0.29 (95% CI: 0.18-0.47; P<0.01). Subgroup analyses were conducted on the basis of ethnicity and study treatment, all the results were not materially altered and did not draw different conclusions, indicating that our results were robust. In summary, this meta-analysis suggests that KRAS mutations may represent negative predictive biomarkers for tumor response in NSCLC patients treated with EGFR-TKIs. However, due to a mutually exclusive relationship between KRAS and EGFR mutation and no difference in survival between KRAS mutant/EGFR wild-type and KRAS wild-type/EGFR wild-type NSCLC, the clinical usefulness of KRAS mutation as a selection marker for EGFR-TKIs sensitivity in NSCLC is limited.

    Lung cancer (Amsterdam, Netherlands) 2010;69;3;272-8

  • PTEN mutations and relationship to EGFR, ERBB2, KRAS, and TP53 mutations in non-small cell lung cancers.

    Jin G, Kim MJ, Jeon HS, Choi JE, Kim DS, Lee EB, Cha SI, Yoon GS, Kim CH, Jung TH and Park JY

    Department of Biochemistry and Molecular Biology, School of Medicine, Kyungpook National University, Dong In 2Ga 101, Daegu 700-422, Republic of Korea.

    Somatic mutations of phosphatase and tensin homolog deleted on chromosome ten (PTEN) in non-small cell lung cancers (NSCLCs) have been investigated in but a small number of cases. In addition, the relationship between PTEN mutations and epidermal growth factor receptor (EGFR), KRAS, and TP53 mutations has not been investigated. Therefore, we investigated the frequency of PTEN mutations in 176 surgically resected NSCLCs and analyzed the relationship between PTEN mutations and EGFR, ERBB2, KRAS, and TP53 mutations. Mutations of PTEN (exons 1-9), EGFR (exons 18-21), ERBB2 (exons 19 and 20), KRAS (exon 1), and TP53 (exons 2-11) were determined by polymerase chain reaction and direct sequencing. PTEN mutations were present in 8 (4.5%) of the 176 tumors. PTEN mutations were only found in ever-smokers and were significantly more frequent in squamous cell carcinoma than in adenocarcinoma (10.2% vs 1.7%, P=0.02). Mutations of EGFR, ERBB2, KRAS, and TP53 genes were found in 36 (20.5%), 2 (1.1%), 11 (6.3%), and 66 (37.5%) cases, respectively. Of the 8 tumors with PTEN mutations, 1 case concurrently had an EGFR mutation and 4 cases had TP53 mutations. However, PTEN mutations were not found in the tumors with KRAS mutation. Our findings indicate that PTEN mutations are relatively common in NSCLC, and thus analysis of PTEN mutations may facilitate a comprehensive understanding of the genetic alterations related to the EGFR signaling pathway.

    Lung cancer (Amsterdam, Netherlands) 2010;69;3;279-83

  • Circulating free DNA, p53 antibody and mutations of KRAS gene in endometrial cancer.

    Dobrzycka B, Terlikowski SJ, Mazurek A, Kowalczuk O, Niklinska W, Chyczewski L and Kulikowski M

    Department of Obstetrics and Gynecology, Medical University of Bialystok, Bialystok, Poland.

    This study was conducted to evaluate the significance of circulating free DNA (CFDNA), p53 antibody (p53-Ab) and mutations of KRAS gene in the development of endometrial cancer (EC). A total of 109 patients with EC (87 patients with Type I and 22 patients with Type II) took part in this study. KRAS mutations and CFDNA were detected by means of the PCR-RFLP and enriched by the PCR-RFPL method. ELISA was used to analyze plasma p53-Ab. Tissue expression of P53 protein was evaluated immunohistochemically (IHC). The frequency of KRAS mutations was especially high in Grade 2 of Type I EC. CFDNA was frequently detected in patients with early stage of Type II EC at a low level of grade. It is noteworthy that the p53-Ab positive rate increased in the higher grade of Type I tumors. A significant difference in the number of cases with the p53-Ab was found in the advanced stage of Type I tumors. The frequency of KRAS and p53-Ab correlates with tumor stage only in the Type I EC. Plasma CFDNA and p53-Ab offer a chance to develop a procedure for EC Type II diagnosis. The association between tumor cells related to CFDNA and p53-Ab with Type II tumor suggests that it might potentially serve as a marker in predicting the prognosis and offers a possibility to individualize treatment regimen.

    International journal of cancer 2010;127;3;612-21

  • Clinicopathological and protein characterization of BRAF- and K-RAS-mutated colorectal cancer and implications for prognosis.

    Zlobec I, Bihl MP, Schwarb H, Terracciano L and Lugli A

    Institute for Pathology, University Hospital of Basel, Basel, Switzerland.

    Recent evidence highlights the potential prognostic and predictive value of BRAF and K-RAS gene alterations in patients with colorectal cancer. However, a comprehensive evaluation of BRAF and K-RAS mutations and their specific clinicopathological features, histomorphological presentation and effect on protein expression have not been systematically analyzed. The aim of this study was to characterize the clinicopathological, histomorphological and protein expression profiles of BRAF- and K-RAS-mutated colorectal cancers and determine their impact on patient survival. Molecular analysis for microsatellite instability (MSI), K-RAS and BRAF was carried out on paraffin-embedded samples from 404 patients with primary colorectal cancer. Using tissue microarrays, 36 tumor-associated and 14 lymphocyte/inflammatory-associated markers were evaluated by immunohistochemistry. BRAF mutation was associated with right-sided tumor location (p < 0.001), higher tumor grade (p = 0.029), absence of peritumoral lymphocytic inflammation (p = 0.026) and MSI-H (p < 0.001). In right-sided tumors, loss of CDX2 expression was observed in 23 of 24 cases (95.8%). BRAF mutation was a poor prognostic indicator in patients with right-sided disease (p = 0.01). This result was maintained in multivariable analysis (p < 0.001; HR = 2.82; 95% CI: 1.5-5.5) with pT, pN and vascular invasion and independent of CDX2 expression. K-RAS mutation, in contrast, was not associated with any of the features analyzed. BRAF gene mutation is an adverse prognostic factor in right-sided colon cancer patients independent of MSI status and, moreover, in patients with lymph node-negative disease. These results indicate that molecular analysis for BRAF may be a useful biomarker for identifying patients with right-sided colon cancer with poor outcome who may benefit from a more individualized course of therapy.

    International journal of cancer 2010;127;2;367-80

  • Clinical outcome of patients with non-small cell lung cancer receiving front-line chemotherapy according to EGFR and K-RAS mutation status.

    Kalikaki A, Koutsopoulos A, Hatzidaki D, Trypaki M, Kontopodis E, Stathopoulos E, Mavroudis D, Georgoulias V and Voutsina A

    Laboratory of Tumor Cell Biology, School of Medicine, University of Crete, Greece.

    Background: Somatic mutations in EGFR and K-RAS may predict for sensitivity and resistance to EGFR tyrosine kinase inhibitors (TKIs). Whether EGFR and K-RAS mutations could also predict clinical outcome of non-small cell lung cancer (NSCLC) patients following front-line chemotherapy has not yet been established.

    One hundred and sixty-two chemotherapy-naïve patients with locally advanced/metastatic NSCLC who received front-line chemotherapy were included in this retrospective study and their clinical outcome data was analyzed according to EGFR and K-RAS mutation status of their tumors.

    Results: Classical activating EGFR and K-RAS mutations were found in 8.2 and 22.6% of patients respectively and were not associated with patients' clinicopathological characteristics. Patients with classical EGFR mutations had a higher probability of response to front-line chemotherapy as compared to those with wild type EGFR (p=0.023). Multivariate analysis showed that the presence of activating EGFR mutations was an independent factor associated with response to front-line chemotherapy (HR=4.85; 95% CI: 1.13-20.83, p=0.034). K-RAS mutation status was not associated with response to front-line chemotherapy. The presence of activating EGFR but not of K-RAS mutations was associated with a significantly higher overall survival compared to patients without mutations treated with platinum-based front-line chemotherapy (p=0.043).

    Conclusions: The data indicate that EGFR mutation status could be predictive for response to cytotoxic front-line chemotherapy in patients with NSCLC. Additional prospective studies are needed in order to validate this observation and to define whether these patients should be preferentially treated with front-line TKIs or chemotherapy.

    Lung cancer (Amsterdam, Netherlands) 2010;69;1;110-5

  • KRAS mutation, KRAS-LCS6 polymorphism, and non-small cell lung cancer.

    Nelson HH, Christensen BC, Plaza SL, Wiencke JK, Marsit CJ and Kelsey KT

    Masonic Cancer Center, Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, MN 55455, USA. hhnelson@umn.edu

    The let-7 family of microRNAs are important regulatory molecules in lung cancer. One downstream target of let-7 is the RAS gene family, including KRAS, an important oncogene in the etiology and clinical outcome of lung adenocarcinoma. Recently, a SNP in the let-7 binding region of the KRAS 3' UTR was identified (termed LCS6). This functional polymorphism alters let-7 binding, resulting in both increased KRAS expression and decreased let-7 exposure. Further, this SNP has been reported as a risk trait for lung cancer among low-moderate smokers. Given the functionality of LCS6, we tested the hypothesis that this SNP is associated with the occurrence of KRAS mutation as well as patient survival. Here, we report there is no association between the LCS6 KRAS polymorphism and KRAS mutation. Further, we find no association between the LCS6 polymorphism and lung cancer survival. These unexpected findings imply that this newly reported KRAS-LCS6 polymorphism will have limited clinical utility for NSCLC.

    Funded by: NCI NIH HHS: P30 CA-077598, P30 CA077598-11

    Lung cancer (Amsterdam, Netherlands) 2010;69;1;51-3

  • Multiple genetic alterations in papillary thyroid cancer are associated with younger age at presentation.

    Moses W, Weng J, Khanafshar E, Duh QY, Clark OH and Kebebew E

    Department of Surgery, University of California, San Francisco, California 94143, USA.

    Background: There is a significant gender and age disparity in thyroid cancer incidence and outcome. The molecular basis for these divergent clinical presentations and outcome are essentially unknown.

    Methods: The primary tumor genotype in 217 patients with papillary thyroid cancer was determined for six common somatic genetic alterations (RET/PTC1, RET/PTC3, and NTRK1 rearrangements, and BRAF V600E, KRAS, and NRAS hotspot mutations) by PCR and direct sequencing, and nested PCR. Univariate and multivariate analyses were performed to determine the association of genetic changes and age, gender, and other clinicopathologic factors.

    Results: One hundred twenty-one of the 190 conventional papillary thyroid carcinoma samples (63.7%) had at least one genetic alteration, and 27 of the samples (14.2%) had more than one alteration. In the follicular variant of papillary thyroid carcinomas, 13 of the 27 samples (48.1%) had at least one genetic alteration and three of the 27 samples (11.1%) had more than one. The presence of multiple genetic alterations was associated with younger age at diagnosis (P=0.034), mean difference of 8 y earlier. We found no significant association with the number or type of genetic alterations present by gender, tumor size, extent of tumor differentiation, multicentricity, lymph node metastasis, distant metastases, TNM stage, and the AMES risk group. The association of multiple genetic alterations and younger age were independent of tumor size, lymph node or distant metastasis, TNM stage, or AMES risk group.

    Conclusions: Multiple genetic alterations are more common in younger patients with papillary thyroid cancer, but there is no difference in the type or number of genetic alterations by gender. Our findings suggest that multiple genetic alterations in thyroid cancer may be associated with earlier disease initiation and or progression.

    The Journal of surgical research 2010;160;2;179-83

  • KRAS and BRAF mutational status in primary colorectal tumors and related metastatic sites: biological and clinical implications.

    Italiano A, Hostein I, Soubeyran I, Fabas T, Benchimol D, Evrard S, Gugenheim J, Becouarn Y, Brunet R, Fonck M, François E, Saint-Paul MC and Pedeutour F

    Laboratory of Solid Tumors Genetics, Nice University Hospital, Nice, France. italiano@bergonie.org

    Background: KRAS and BRAF mutations in primary colorectal tumors (PT) are predictive of nonresponse to anti-epidermal growth factor receptor (EGFR) antibodies in patients with metastatic colorectal cancer (mCRC). The question of primary resistance to anti-EGFR treatment as a result of the presence of KRAS or BRAF mutations only in metastases has been raised but not resolved.

    Methods: We analyzed the mutational status of KRAS and BRAF in 64 new patients with mCRC and performed a systematic review of published data from 285 patients.

    Results: A total of 285 and 95 matched PT/metastases were available for the analysis of the KRAS and the BRAF status, respectively. An identical mutational pattern of KRAS in PT and the matching metastases were reported in all the cases but 14 (5%). In six cases (2%), KRAS was mutated in the PT and wild type in the metastatic site, whereas in eight cases (3%), KRAS was wild type in the PT and mutated in the metastatic site. An identical mutational pattern of BRAF in PT and the matching metastases was reported in all but two cases (3%). In one case (1.5%), BRAF was mutated in the PT and wild type in the metastatic site, whereas in one case (1.5%), BRAF was wild type in the PT and mutated in the metastatic site.

    Conclusions: The acquisition by metastases of a KRAS or a BRAF mutation that was not present in the PT is a rare event, occurring in 5% of cases of mCRC. This is not a frequent mechanism of primary resistance to anti-EGFR treatments in mCRC.

    Annals of surgical oncology 2010;17;5;1429-34

  • Predictors of gefitinib outcomes in advanced non-small cell lung cancer (NSCLC): study of a comprehensive panel of molecular markers.

    Tiseo M, Rossi G, Capelletti M, Sartori G, Spiritelli E, Marchioni A, Bozzetti C, De Palma G, Lagrasta C, Campanini N, Camisa R, Boni L, Franciosi V, Rindi G and Ardizzoni A

    Division of Medical Oncology, University Hospital of Parma, Via Gramsci 14, 43100 Parma, Italy. mtiseo@ao.pr.it

    A number of different clinical characteristics and molecular markers related to epidermal growth factor receptor (EGFR) activation have been reported to singly correlate with therapeutic activity of EGFR tyrosine kinase inhibitors (TKIs) in advanced non-small cell lung cancer (NSCLC). This study was designed to evaluate the predictive value on gefitinib outcomes of a comprehensive panel of molecular parameters in advanced NSCLC patients. EGFR and K-ras mutations were detected by direct sequencing on tumor DNA from paraffin embedded samples. EGFR and HER2 gene copy number was assessed by FISH. EGFR protein expression was quantified by immunohistochemistry. EGFR gene intron 1 polymorphism was assessed on genomic DNA isolated from venous whole blood samples. Ninety-one patients were prospectively enrolled and the overall gefitinib response rate was 18.7% (2 complete and 15 partial responses). Sex (p=0.005), non-smoking status (p=0.010), skin toxicity (p=0.020), EGFR gene mutations (p<0.001) and EGFR FISH positivity (p=0.016) were found to be associated with gefitinib response. K-ras mutation was detected in only seven non-responder patients. The median overall survival was of 10 months. Only non-smoking status and EGFR intron 1 polymorphism showed a statistically significant correlation with survival (p=0.031 and 0.044, respectively). In conclusion, we have confirmed the role of EGFR gene mutation as predictor of response to EGFR TKIs. Moreover, EGFR gene copy number and, potentially, also EGFR intron 1 polymorphism could aid in better prediction of EGFR TKI responsiveness in advanced NSCLC.

    Lung cancer (Amsterdam, Netherlands) 2010;67;3;355-60

  • Molecular predictors of outcome with gefitinib and docetaxel in previously treated non-small-cell lung cancer: data from the randomized phase III INTEREST trial.

    Douillard JY, Shepherd FA, Hirsh V, Mok T, Socinski MA, Gervais R, Liao ML, Bischoff H, Reck M, Sellers MV, Watkins CL, Speake G, Armour AA and Kim ES

    M. D. Anderson Cancer Center, Thoracic/Head and Neck Medical Oncology, Box 432, 1515 Holcombe Blvd, Houston, TX 77401, USA.

    PURPOSE In the phase III INTEREST trial, 1,466 pretreated patients with advanced non-small cell lung cancer (NSCLC) were randomly assigned to receive gefitinib or docetaxel. As a preplanned analysis, we prospectively analyzed available tumor biopsies to investigate the relationship between biomarkers and clinical outcomes. METHODS Biomarkers included epidermal growth factor receptor (EGFR) copy number by fluorescent in situ hybridization (374 assessable samples), EGFR protein expression by immunohistochemistry (n = 380), and EGFR (n = 297) and KRAS (n = 275) mutations. Results For all biomarker subgroups analyzed, survival was similar for gefitinib and docetaxel, with no statistically significant differences between treatments and no significant treatment by biomarker status interaction tests. EGFR mutation-positive patients had longer progression-free survival (PFS; hazard ratio [HR], 0.16; 95% CI, 0.05 to 0.49; P = .001) and higher objective response rate (ORR; 42.1% v 21.1%; P = .04), and patients with high EGFR copy number had higher ORR (13.0% v 7.4%; P = .04) with gefitinib versus docetaxel. CONCLUSION These biomarkers do not appear to be predictive factors for differential survival between gefitinib and docetaxel in this setting of previously treated patients; however, subsequent treatments may have influenced the survival results. For secondary end points of PFS and ORR, some advantages for gefitinib over docetaxel were seen in EGFR mutation-positive and high EGFR copy number patients. There was no statistically significant difference between gefitinib and docetaxel in biomarker-negative patients. This suggests gefitinib can provide similar overall survival to docetaxel in patients across a broad range of clinical subgroups and that EGFR biomarkers such as mutation status may additionally identify which patients are likely to gain greatest PFS and ORR benefit from gefitinib.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2010;28;5;744-52

  • Activating KRAS mutations and overexpression of epidermal growth factor receptor as independent predictors in metastatic colorectal cancer patients treated with cetuximab.

    Yen LC, Uen YH, Wu DC, Lu CY, Yu FJ, Wu IC, Lin SR and Wang JY

    Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.

    Objective: Cetuximab, a monoclonal antibody targeting epidermal growth factor receptor (EGFR), has been proven to be efficient in metastatic colorectal cancer (mCRC); however, the therapeutic response is variable and markers predictive of response are urgently required. This study was conducted to determinate the predictive values of KRAS mutation status and EGFR expression in mCRC patients treated with cetuximab plus chemotherapy.

    Clinical benefit with EGFR-targeting antibodies seems to be restricted to a particular subgroup of mCRC patients. Therefore, the identification of reliable predictive factors for mCRC patients is imperative before the introduction of targeted chemotherapy.

    Methods: Ninety-five mCRC patients receiving cetuximab plus the FOLFIRI or FOLFOX-4 chemotherapy were enrolled into the present study. KRAS mutation status/EGFR expression levels were analyzed using direct sequencing, immunohistochemistry (IHC), and reverse transcription-polymerase chain reaction (RT-PCR) assay, respectively. The association between clinical response, progression-free survival (PFS) and overall survival (OS) as well as KRAS mutation status/EGFR expression levels were evaluated.

    Results: Of 95 mCRC patients, KRAS mutations were identified in 41 cases, and EGFR overexpression (protein or mRNA levels) were observed in 78 patients. Among 41 tumors with KRAS mutation, 33 were found to be activating mutants at codons 12, 13, 15 or 18, while 8 were nonactivating mutants at codons 20, 30, or 31. Fifty-five patients responded to cetuximab plus chemotherapy, 49 were EGFR overexpression and 46 were wild-type KRAS tumor status. Patients with tumors that express high EGFR levels or harbor wild-type KRAS are more likely to have a better PFS and OS when treated with cetuximab plus chemotherapy (all P < 0.05). Furthermore, patients with nonactivating KRAS mutants in tumors had a significantly better PFS and OS than patients with activating KRAS mutants (both P < 0.05). However, for patients with wild-type KRAS tumor status, EGFR expression remains a relevant predictor of clinical response.

    Conclusions: The study suggests that activating KRAS mutants is a particularly important independent predictive marker in mCRC patients treated with cetuximab plus chemotherapy, of which combing activating KRAS mutants and EGFR could help to identify the subgroup of patients who are most likely to respond to cetuximab plus chemotherapy.

    Annals of surgery 2010;251;2;254-60

  • Clinicopathological predictors of EGFR/KRAS mutational status in primary lung adenocarcinomas.

    Dacic S, Shuai Y, Yousem S, Ohori P and Nikiforova M

    Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15213, USA. dacics@upmc.edu

    Screening for EGFR and KRAS mutations in patients with lung adenocarcinomas can be used to predict the patient's response to EGFR tyrosine kinase inhibitors, but there is a lack of guidelines for testing in clinical practice. We analyzed the morphological and clinicopathological characteristics, including tumor stage, size, presence of scar, inflammatory response, angiolymphatic and pleural invasion, of 345 surgically treated primary lung adenocarcinomas with respect to their EGFR and KRAS mutational profile and EGFR FISH. EGFR and KRAS mutations were found in 33 (10%) and 78 (23%) of lung adenocarcinomas, respectively, whereas 226 (67%) cases were negative for both mutations. There was a large overlap in the analyzed clinicopathological characteristics among the three study groups. Statistically significant predictors for the presence of EGFR mutations included history of never smoking (OR 5.939; 95% Wald confidence limit 1.662-21.223, P=0.0149), mild lymphocytic host response (OR 4.724; 95% Wald confidence limit 1.33-1.776; P=0.0163), female gender (OR 2.571; 95% Wald confidence limit 1.015-6.511, P=0.0463) and absence of solid growth pattern. Statistically significant predictors for the presence of KRAS mutations included older age (OR 1.034; 95% Wald confidence limit 1.007-1.062, P=0.0132), history of smoking (OR 0.617, 95% Wald confidence limit 0.357-1.066, P=0.0412) and mucinous differentiation. EGFR FISH positivity as defined by the Colorado criteria was a significant predictor of EGFR mutations, with high polysomy as the strongest predictive criteria. Despite statistically significant differences among the study groups and because of the large overlap in the analyzed clinicopathological criteria, none of these could be implemented as the selection criteria for molecular testing in clinical practice. The cost-effectiveness of lung carcinoma mutational testing would be improved by initial determination of KRAS mutational status as negative predictor of the patient's response to EGFR tyrosine kinase inhibitors, followed by EGFR mutational analysis, if necessary.

    Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc 2010;23;2;159-68

  • Genetic and proteomic features associated with survival after treatment with erlotinib in first-line therapy of non-small cell lung cancer in Eastern Cooperative Oncology Group 3503.

    Amann JM, Lee JW, Roder H, Brahmer J, Gonzalez A, Schiller JH and Carbone DP

    Department of Cancer Biology, Vanderbilt University, Nashville, Tennessee, USA.

    Introduction: Serum proteomics and mutations in the epidermal growth factor receptor (EGFR) and KRAS have been associated with benefit after therapy with EGFR-targeted therapies in non-small cell lung cancer, but all three have not been evaluated in any one study.

    Hypothesis: Pretreatment serum proteomics predicts survival in Western advanced non-small cell lung cancer patients with wild-type EGFR and independent of KRAS mutation status.

    Methods: We analyzed available biospecimens from Eastern Cooperative Oncology Group 3503, a single-arm phase II study of erlotinib in first-line advanced lung cancer, for proteomics signatures in the previously described serum matrix-assisted laser desorption ionization proteomic classifier (VeriStrat) as well as for KRAS and EGFR mutations.

    Results: Out of 137 enrolled patients, analyzable biologic samples were available on 102. Nine of 41 (22%) demonstrated KRAS mutations and 3 of 41 (7%) harbored EGFR mutations. VeriStrat classification identified 64 of 88 (73%) as predicted to have "good" and 24 of 88 (27%) predicted to have "poor" outcomes. A statistically significant correlation of VeriStrat status (p < 0.001) was found with survival. EGFR mutations, but not KRAS mutations, also correlated with survival.

    Conclusions: The previously defined matrix-assisted laser desorption ionization predictor remains a potent and highly clinically significant predictor of survival after first-line treatment with erlotinib in patients with wild-type EGFR and independent of mutations in KRAS.

    Funded by: NCI NIH HHS: CA23318, P50 CA090949, P50 CA90949, U01 CA114771, U01 CA114771-03, U10 CA016116, U10 CA016116-37, U10 CA023318, U24 CA114737

    Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer 2010;5;2;169-78

  • Genetic susceptibility to distinct bladder cancer subphenotypes.

    Guey LT, García-Closas M, Murta-Nascimento C, Lloreta J, Palencia L, Kogevinas M, Rothman N, Vellalta G, Calle ML, Marenne G, Tardón A, Carrato A, García-Closas R, Serra C, Silverman DT, Chanock S, Real FX, Malats N and EPICURO/Spanish Bladder Cancer Study investigators

    Spanish National Cancer Research Centre, Madrid, Spain.

    Background: Clinical, pathologic, and molecular evidence indicate that bladder cancer is heterogeneous with pathologic/molecular features that define distinct subphenotypes with different prognoses. It is conceivable that specific patterns of genetic susceptibility are associated with particular subphenotypes.

    Objective: To examine evidence for the contribution of germline genetic variation to bladder cancer heterogeneity.

    The Spanish Bladder Cancer/EPICURO Study is a case-control study based in 18 hospitals located in five areas in Spain. Cases were patients with a newly diagnosed, histologically confirmed, urothelial cell carcinoma of the bladder from 1998 to 2001. Case diagnoses were reviewed and uniformly classified by pathologists following the World Health Organisation/International Society of Urological Pathology 1999 criteria. Controls were hospital-matched patients (n=1149).

    Measurements: A total of 1526 candidate variants in 423 candidate genes were analysed. Three distinct subphenotypes were defined according to stage and grade: low-grade nonmuscle invasive (n=586), high-grade nonmuscle invasive (n=219), and muscle invasive (n=246). The association between each variant and subphenotype was assessed by polytomous risk models adjusting for potential confounders. Heterogeneity in genetic susceptibility among subphenotypes was also tested.

    Two established bladder cancer susceptibility genotypes, NAT2 slow-acetylation and GSTM1-null, exhibited similar associations among the subphenotypes, as did VEGF-rs25648, which was previously identified in our study. Other variants conferred risks for specific tumour subphenotypes such as PMS2-rs6463524 and CD4-rs3213427 (respective heterogeneity p values of 0.006 and 0.004), which were associated with muscle-invasive tumours (per-allele odds ratios [95% confidence interval] of 0.56 [0.41-0.77] and 0.71 [0.57-0.88], respectively) but not with non-muscle-invasive tumours. Heterogeneity p values were not robust in multiple testing according to their false-discovery rate.

    Conclusions: These exploratory analyses suggest that genetic susceptibility loci might be related to the molecular/pathologic diversity of bladder cancer. Validation through large-scale replication studies and the study of additional genes and single nucleotide polymorphisms are required.

    Funded by: Intramural NIH HHS: ZIA CP010136-16

    European urology 2010;57;2;283-92

  • K-ras mutation status correlates with the expression of VEGFR1, VEGFR2, and PDGFRalpha in colorectal cancer.

    Schimanski CC, Zimmermann T, Schmidtmann I, Gockel I, Lang H, Galle PR, Moehler M and Berger MR

    First Department of Internal Medicine, Johannes Gutenberg University of Mainz, Langenbeckstrasse 1, Mainz 55101, Germany. schimanski@1-med.klinik.uni-mainz.de

    Aim: We initiated this study in order to analyze whether the expression level of targeted receptor tyrosine kinases (RTK) is associated with the K-ras mutation status.

    Methods: The expression pattern of VEGFR1, VEGFR2, VEGFR3, PDGFRalpha, PDGFRbeta, and EGFR1 was analyzed in 93 samples of human colorectal carcinoma samples and correlated with the K-ras mutation status as identified by PCR-RFLP.

    Results: VEGFR1, VEGFR2, VEGFR3, PDGFRalpha, PDGFRbeta, and EGFR1 were expressed at relevant levels in 95%, 46%, 46%, 85%, 62%, and 82%, respectively. K-ras mutations were present in 53% (codon 12, 47%; codon 13, 6%). Expression of VEGFR1 (P = 0.0263), VEGFR2 (P = 0.0466), and PDGFRalpha (P = 0.0063) was significantly linked to K-ras codon 12 or 13 mutation. In addition, co-expression of VEGFR2 and PDGFRalpha was significantly associated with K-ras mutation (P = 0.0145).

    Conclusion: Our data reveal that specific RTKs are over-expressed in K-ras mutated cancers. It needs to be addressed in prospective studies whether these patients will benefit from tyrosine kinase inhibitors more than K-ras wild-type.

    International journal of colorectal disease 2010;25;2;181-6

  • KRAS mutation and microsatellite instability: two genetic markers of early tumor development that influence the prognosis of colorectal cancer.

    Nash GM, Gimbel M, Cohen AM, Zeng ZS, Ndubuisi MI, Nathanson DR, Ott J, Barany F and Paty PB

    Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, USA.

    Introduction: We examined two genetic markers established early in colorectal tumor development, microsatellite instability (MSI) and mutation of the KRAS proto-oncogene, to see if these genetic changes influence metastatic disease progression and survival.

    MSI and KRAS mutation status were assessed in 532 primary adenocarcinomas (stage I-IV) from patients treated by colon resection. Median follow-up was 4.1 years (range 0-13.3 years) overall, 5.4 years for survivors.

    Results: MSI and KRAS mutation were detected in 12 and 36% of cases, respectively. MSI was more common in early-stage disease (I, 15%; II, 21%; III, 10%; IV, 2%; P = 0.0001). Prevalence of KRAS mutation did not vary with stage (I, 36%; II, 34%; III, 35%; IV, 40%; P = ns). Disease-specific survival was far superior for MSI tumors than for microsatellite stability (MSS) tumors (5-year survival 92 vs. 59%, P < 0.0001). KRAS mutation was a marker of poor survival (5-year survival 55 vs. 68%, P = 0.0002). Using Cox regression analysis MSI, KRAS mutation, and stage were strong independent predictors of survival in the entire patient population. A high-mortality group with MSS/KRAS-mutant tumors was identified within the stage I and II cohort.

    Conclusions: MSI and KRAS mutation provide fundamental genetic signatures influencing tumor behavior across patient subsets and stages of tumor development.

    Funded by: NCI NIH HHS: 2 P01 CA65930-05A2

    Annals of surgical oncology 2010;17;2;416-24

  • KRAS mutation correlates with accelerated metastatic progression in patients with colorectal liver metastases.

    Nash GM, Gimbel M, Shia J, Nathanson DR, Ndubuisi MI, Zeng ZS, Kemeny N and Paty PB

    Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.

    Background: Observational studies of patients with primary colorectal cancer have identified KRAS mutation as a marker of poor prognosis. To examine more directly whether KRAS mutations are associated with accelerated metastatic progression, we evaluated KRAS mutation as well as Ki-67 expression in patients with colorectal liver metastases not treated with cetuximab.

    Methods: KRAS mutation status was assessed in a series of resected or sampled colorectal liver metastases. In a subset of these tumors, Ki-67 antigen expression was assessed by immunohistochemical stains. Median follow-up after liver resection or biopsy was 2.3 years.

    Results: KRAS mutation in the liver metastasis was detected in 27% of the 188 patients. High Ki-67 expression in the liver metastasis was identified in 62% of 124 patients analyzed. Both markers were associated with multiple liver metastases and shorter time interval to their detection. KRAS mutation and high Ki-67 expression were independent predictors of poor survival after colon resection (hazard ratio [HR] 1.9 [95% confidence interval (95% CI), 1.1-3.4], HR 2.6 [95% CI, 1.4-4.8], respectively). Tumors with high Ki-67 expression were less likely to be selected for liver resection, and KRAS mutation was independently associated with poor survival after liver resection (HR 2.4 [95% CI, 1.4-4.0]).

    Conclusions: KRAS mutation is associated with more rapid and aggressive metastatic behavior of colorectal liver metastases. These data suggest an important role for KRAS activation in colorectal cancer progression and support continued efforts to develop KRAS pathway inhibitors for this disease.

    Funded by: NCI NIH HHS: 2 P01 CA65930-05A2

    Annals of surgical oncology 2010;17;2;572-8

  • Mutual exclusion of ASXL1 and NPM1 mutations in a series of acute myeloid leukemias.

    Carbuccia N, Trouplin V, Gelsi-Boyer V, Murati A, Rocquain J, Adélaïde J, Olschwang S, Xerri L, Vey N, Chaffanet M, Birnbaum D and Mozziconacci MJ

    Leukemia 2010;24;2;469-73

  • Predictive factors for the efficacy of cetuximab plus chemotherapy as salvage therapy in metastatic gastric cancer patients.

    Park SR, Kook MC, Choi IJ, Kim CG, Lee JY, Cho SJ, Kim YW, Ryu KW, Lee JH, Lee JS, Park YI and Kim NK

    Center for Gastric Cancer, Research Institute and Hospital, National Cancer Center, 111 Jungbalsan-ro, Ilsandong-gu, Goyang, Gyeonggi, 410-769, Republic of Korea. sukryun73@hanmail.net

    Purpose: We performed a retrospective study to evaluate the efficacy of cetuximab plus chemotherapy in metastatic gastric cancer (MGC) patients previously treated with chemotherapy and to investigate potential predictors of treatment efficacy in those patients.

    Methods: Thirty-two patients with MGC were included in this study. Cetuximab was delivered, often combined with irinotecan-based chemotherapy. Thirty patients were analyzed for K-ras mutations via direct sequencing of the tumor DNA.

    Results: Patients were heavily pretreated with a median number of three previous lines of palliative chemotherapy (56% of the patients were refractory to all of the following drugs: fluoropyrimidines, cisplatin, irinotecan, oxaliplatin, and docetaxel) and 53% of the patients displayed poor performance status. Of 28 response-assessable patients, the overall response rate to cetuximab plus chemotherapy was 3.6% [95% confidence interval (CI) 0-10.5%] and the disease control rate was 28.6%. The median progression-free survival (PFS) was 1.7 months (95% CI 1.3-2.1 months), and the median overall survival (OS) was 3.2 months (95% CI 1.4-5.0 months). Multivariate analyses revealed that skin rash and performance status were significantly associated with PFS and OS. The presence of a K-ras mutation (13.3%) was not associated with either PFS or OS.

    Conclusion: Our study suggests that MGC patients with good performance status and skin rash benefit most from salvage cetuximab combined with chemotherapy, even in heavily pretreated status.

    Cancer chemotherapy and pharmacology 2010;65;3;579-87

  • Rare mutations in the PIK3CA gene contribute to aggressive endometrial cancer.

    Konstantinova D, Kaneva R, Dimitrov R, Savov A, Ivanov S, Dyankova T, Kremensky I and Mitev V

    1 Department of Chemistry and Biochemistry, Medical University-Sofia, Sofia, Bulgaria. darivko@gmail.com

    The molecular basis of endometrial cancer (EC), a common gynecologic malignancy, often includes mutational activation of the PIK3CA and KRAS genes. We aimed to determine the distribution of mutations in the two genes depending on patient clinocopathological characteristics. We sequenced exon 1 of the KRAS gene and exons 9 and 20 of the PIK3CA gene in 108 consecutive EC tumor samples. PIK3CA mutations were present in 24 of the 108 (22.2%) cases and KRAS mutations in 18 of the 108 (16.7%) cases. PIK3CA mutations occurred more frequently in KRAS-mutated samples (7/18, 38.9%; p = 0.06) than in KRAS wild type (17/90, 18.9%) and showed a very high frequency in metastatic tumors (4/9, 44.4%; p = 0.1) and in samples displaying serous differentiation-serous and mixed endometrioid/serous tumors (6/12, 50.0%; p = 0.021)-where KRAS mutations were rare (11.1% and 16.7%, respectively) and did not exist independently of a PIK3CA mutation. Non-hotspot (i.e., non-E542K, -E545K, and -H1047R) mutations in the PIK3CA gene showed higher frequency in metastatic cases (3/9, 33.3%; p = 0.05). Tumors displaying serous differentiation showed a particular pattern-they harbored exclusively mutations in PIK3CA exon 20 (5/12, 41.7%; p = 0.005) and most of these were non-hotspot (4/12, 33.3%; p = 0.02). In all other comparisons exons 9 and 20 mutation distribution did not differ. These results suggest the need for further exploration of the significance of PIK3CA mutations in respect to aggressive EC.

    DNA and cell biology 2010;29;2;65-70

  • Warburg effect revisited: an epigenetic link between glycolysis and gastric carcinogenesis.

    Liu X, Wang X, Zhang J, Lam EK, Shin VY, Cheng AS, Yu J, Chan FK, Sung JJ and Jin HC

    Institute of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China.

    In cancer cells, glucose is often converted into lactic acid, which is known as the 'Warburg effect'. The reason that cancer cells have a higher rate of aerobic glycolysis, but not oxidative phosphorylation, remains largely unclear. Herein, we proposed an epigenetic mechanism of the Warburg effect. Fructose-1,6-bisphosphatase-1 (FBP1), which functions to antagonize glycolysis was downregulated through NF-kappaB pathway in Ras-transformed NIH3T3 cells. Restoration of FBP1 expression suppressed anchorage-independent growth, indicating the relevance of FBP1 downregulation in carcinogenesis. Indeed, FBP1 was downregulated in gastric carcinomas (P<0.01, n=22) and gastric cancer cell lines (57%, 4/7). Restoration of FBP1 expression reduced growth and glycolysis in gastric cancer cells. Moreover, FBP1 downregulation was reversed by pharmacological demethylation. Its promoter was hypermethylated in gastric cancer cell lines (57%, 4/7) and gastric carcinomas (33%, 33/101). Inhibition of NF-kappaB restored FBP1 expression, partially through demethylation of FBP1 promoter. Notably, Cox regression analysis revealed FBP1 promoter methylation as an independent prognosis predicator for gastric cancer (hazard ratio: 3.60, P=0.010). In summary, we found that NF-kappaB functions downstream of Ras to promote epigenetic downregulation of FBP1. Promoter methylation of FBP1 can be used as a new biomarker for prognosis prediction of gastric cancer. Such an important epigenetic link between glycolysis and carcinogenesis partly explains the Warburg effect.

    Oncogene 2010;29;3;442-50

  • Prognostic role of KRAS and BRAF in stage II and III resected colon cancer: results of the translational study on the PETACC-3, EORTC 40993, SAKK 60-00 trial.

    Roth AD, Tejpar S, Delorenzi M, Yan P, Fiocca R, Klingbiel D, Dietrich D, Biesmans B, Bodoky G, Barone C, Aranda E, Nordlinger B, Cisar L, Labianca R, Cunningham D, Van Cutsem E and Bosman F

    Oncosurgery, Geneva UniversityHospital, Geneva, Switzerland. arnaud.roth@sim.hcuge.ch

    Purpose: Mutations within the KRAS proto-oncogene have predictive value but are of uncertain prognostic value in the treatment of advanced colorectal cancer. We took advantage of PETACC-3, an adjuvant trial with 3,278 patients with stage II to III colon cancer, to evaluate the prognostic value of KRAS and BRAF tumor mutation status in this setting.

    Formalin-fixed paraffin-embedded tissue blocks (n = 1,564) were prospectively collected and DNA was extracted from tissue sections from 1,404 cases. Planned analysis of KRAS exon 2 and BRAF exon 15 mutations was performed by allele-specific real-time polymerase chain reaction. Survival analyses were based on univariate and multivariate proportional hazard regression models.

    Results: KRAS and BRAF tumor mutation rates were 37.0% and 7.9%, respectively, and were not significantly different according to tumor stage. In a multivariate analysis containing stage, tumor site, nodal status, sex, age, grade, and microsatellite instability (MSI) status, KRAS mutation was associated with grade (P = .0016), while BRAF mutation was significantly associated with female sex (P = .017), and highly significantly associated with right-sided tumors, older age, high grade, and MSI-high tumors (all P < 10(-4)). In univariate and multivariate analysis, KRAS mutations did not have a major prognostic value regarding relapse-free survival (RFS) or overall survival (OS). BRAF mutation was not prognostic for RFS, but was for OS, particularly in patients with MSI-low (MSI-L) and stable (MSI-S) tumors (hazard ratio, 2.2; 95% CI, 1.4 to 3.4; P = .0003).

    Conclusion: In stage II-III colon cancer, the KRAS mutation status does not have major prognostic value. BRAF is prognostic for OS in MS-L/S tumors.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2010;28;3;466-74

  • Prognostic and predictive value of TOPK stratified by KRAS and BRAF gene alterations in sporadic, hereditary and metastatic colorectal cancer patients.

    Zlobec I, Molinari F, Kovac M, Bihl MP, Altermatt HJ, Diebold J, Frick H, Germer M, Horcic M, Montani M, Singer G, Yurtsever H, Zettl A, Terracciano L, Mazzucchelli L, Saletti P, Frattini M, Heinimann K and Lugli A

    Institute for Pathology, University Hospital of Basel, 4031 Basel, Switzerland. izlobec@uhbs.ch

    Background: Our aim was to investigate the prognostic and predictive value of the oncogenic MAPKK-like protein T-cell-originated protein kinase (TOPK) stratified by KRAS and BRAF mutations in patients with sporadic, hereditary and metastatic colorectal cancer (CRC) treated with anti-EGFR therapy.

    Methods: Immunohistochemistry (IHC) for TOPK was performed on four study groups. Group 1 included two subgroups of 543 and 501 sporadic CRC patients used to test the reliability of TOPK expression by IHC. In Group 2, representing an additional 222 sporadic CRCs, the prognostic effect of TOPK stratified by KRAS and BRAF was assessed. The prognostic effect of TOPK was further analysed in Group 3, representing 71 hereditary Lynch syndrome-associated CRC patients. In Group 4, the predictive and prognostic value of TOPK was analysed on 45 metastatic patients treated with cetuximab or panitumumab stratified by KRAS and BRAF gene status.

    Results: In both sporadic CRC subgroups (Group 1), associations of diffuse TOPK expression with clinicopathological features were reproducible. Molecular analysis of sporadic CRCs in Group 2 showed that diffuse TOPK expression was associated with KRAS and BRAF mutations (p<0.001) and with poor outcome in patients with either mutation in univariate and multivariate analysis (P=0.017). In hereditary patients (Group 3), diffuse TOPK was linked to advanced pT stage. In metastatic patients treated with anti-EGFR therapy (Group 4), diffuse TOPK expression was linked to dismal outcome despite objective response to treatment (P=0.01).

    Conclusions: TOPK expression is an unfavourable prognostic indicator in sporadic patients with KRAS or BRAF mutations and also in patients with metastatic disease experiencing a response to anti-EGFR therapies. The inhibition of TOPK, which could benefit 30-40% of CRC patients, may represent a new avenue of investigation for targeted therapy.

    British journal of cancer 2010;102;1;151-61

  • A comparison of EGFR and KRAS status in primary lung carcinoma and matched metastases.

    Monaco SE, Nikiforova MN, Cieply K, Teot LA, Khalbuss WE and Dacic S

    Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA 15232, USA. monacose@upmc.edu

    Epidermal growth factor receptor (EGFR) and v-Ki-ras 2 (KRAS; viral Kirsten rat sacoma 2 oncogene homolog) oncogenes are predictors of response to EGFR-targeted therapy in lung carcinomas. Morphologic heterogeneity of lung carcinomas is reflected at the molecular level and may confound interpretation of immunohistochemistry, fluorescence in situ hybridization, and mutational assays, which are all used for analysis of KRAS and EGFR genes. Furthermore, molecular characteristics may differ between the primary tumor and corresponding metastases. The aim of this study was to determine if the KRAS and/or EGFR status of primary and metastatic lung carcinoma differs. Three hundred thirty-six cases of primary lung carcinomas were tested for EGFR and KRAS, and 85 cases had a metastasis (25%). Of the 40 cases (47%) with sufficient material for EGFR and KRAS mutational analysis, there were 11 (27.5%) primary tumors and 4 (10%) metastases identified with a KRAS mutation. Of the cases with EGFR fluorescence in situ hybridization results, there were 3 (8%) primary tumors and 8 (24%) metastases that were fluorescence in situ hybridization positive. Overall, there were 9 cases (22.5%) with discordant KRAS status and 11 cases (32.5%) with discordant EGFR fluorescence in situ hybridization status. Our results suggest that the EGFR and KRAS status of primary lung carcinomas may not predict the status in the corresponding metastases. This observation may have important implications for molecular testing for targeted therapies.

    Human pathology 2010;41;1;94-102

  • AKT1 pleckstrin homology domain E17K activating mutation in endometrial carcinoma.

    Cohen Y, Shalmon B, Korach J, Barshack I, Fridman E and Rechavi G

    Department of Obstetrics and Gynecology, Sheba Medical Center, Tel-Hashomer, Israel. ycohen1@gmail.com

    Objectives: The PI3K/AKT pathway is frequently activated in endometrial carcinoma (EC) mainly due to mutations in the PIK3CA and PTEN genes. These events are common and believed to be the key to endometrial carcinogenesis. Recently, a somatic activating mutation in the AKT1 gene (E17K) was identified in several cancer types. In this study we explored the frequency of this AKT1 mutation in endometrial carcinoma.

    Methods: Tumor DNA, extracted from 73 EC was analyzed for AKT1 E17K mutation (G49A) using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). In addition, the tumors were screened for coexisting common mutations in PTEN, PIK3CA and KRAS.

    Results: The AKT1 E17K mutation was detected in 4% of EC. One of the AKT1-mutated tumors showed coexisting PTEN loss-of-function mutation.

    Conclusion: We identified the AKT1 E17K mutation in 4% of endometrial carcinomas. The presence of double AKT1/ PTEN mutants is in accord with the hypothesis that in EC more than one hit is required to completely activate the PI3K pathway. Furthermore, AKT1 mutations were limited to high grade, advanced stage tumors suggesting that this mutation confers a more aggressive tumor behavior.

    Gynecologic oncology 2010;116;1;88-91

  • KRAS and BRAF mutations in patients with rectal cancer treated with preoperative chemoradiotherapy.

    Gaedcke J, Grade M, Jung K, Schirmer M, Jo P, Obermeyer C, Wolff HA, Herrmann MK, Beissbarth T, Becker H, Ried T and Ghadimi M

    Department of General and Visceral Surgery, University Medical Center, Georg-August-University Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany. mghadim@gwdg.de

    KRAS and BRAF are mutated in 35% and 10% of colorectal cancers, respectively. However, data specifically for locally advanced rectal cancers are scarce, and the frequency of KRAS mutations in codons 61 and 146 remains to be established.

    DNA was isolated from pre-therapeutic biopsies of 94 patients who were treated within two phase-III clinical trials receiving preoperative chemoradiotherapy. Mutation status of KRAS exons 1-3 and BRAF exon 15 was established using the ABI PRISM Big Dye Sequencing Kit and subsequently correlated with clinical parameters.

    Results: Overall, KRAS was mutated in 45 patients (48%). Twenty-nine mutations (64%) were located in codon 12, 10 mutations (22%) in codon 13, and 3 mutations (7%) in codons 61 and 146. No V600E BRAF mutation was detected. The presence of KRAS mutations was correlated neither with tumor response or lymph node status after preoperative chemoradiotherapy nor with overall survival or disease-free survival. When KRAS exon 1 mutations were separated based on the amino-acid exchange, we again failed to detect significant correlations (p=0.052). However, G12V mutations appeared to be associated with higher rates of tumor regression than G13D mutations (p=0.012).

    Conclusion: We are the first to report the mutation status of KRAS and BRAF in pre-therapeutic biopsies from locally advanced rectal cancers. The high number of KRAS mutations in codons 61 and 146 emphasizes the importance to expand current mutation analyses, whereas BRAF mutations are not relevant for rectal carcinogenesis. Although the KRAS mutation status was not correlated with response, the subtle difference between G12V and G13D mutations warrants analysis of a larger patient population.

    Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology 2010;94;1;76-81

  • Primary oncocytic adenocarcinomas of the lung: a clinicopathologic, immunohistochemical, and molecular biologic analysis of 16 cases.

    Solis LM, Raso MG, Kalhor N, Behrens C, Wistuba II and Moran CA

    Departments of Pathology, Neck Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.

    Sixteen cases of primary oncocytic adenocarcinomas of the lung are reported. The patients were 11 women and 5 men between the ages of 47 and 81 years (median, 75 years) with symptoms of cough, chest pain, and shortness of breath. Surgical staging disclosed 14 patients (88%) with stage I disease, 1 (6%) with stage II, and 1 (6%) with stage III. Histologically, all the cases displayed prominent oncocytic features with conventional growth patterns, including acinar, papillary, and bronchioloalveolar. Immunohistochemically, the tumors displayed positive staining for keratin 7, thyroid transcription factor-1, and mitochondrial antibody. Molecular studies showed 3 (20%) of 15 tumors with EGFR mutations and 3 additional cases with KRAS mutations. Clinical follow-up of at least 24 months was obtained in all patients and showed that 5 patients had recurrences, 2 patients died of tumor, and 2 other patients died of unrelated conditions. These cases represent an unusual variant of pulmonary adenocarcinoma.

    Funded by: NCI NIH HHS: P30 CA016672

    American journal of clinical pathology 2010;133;1;133-40

  • Use of epidermal growth factor receptor/Kirsten rat sarcoma 2 viral oncogene homolog mutation testing to define clonal relationships among multiple lung adenocarcinomas: comparison with clinical guidelines.

    Girard N, Deshpande C, Azzoli CG, Rusch VW, Travis WD, Ladanyi M and Pao W

    Human Oncology and Pathogenesis Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.

    Background: The incidence of multiple lung adenocarcinomas is rising, making it difficult to determine the stage and assign treatment in an increasing number of patients following surgery. Clinical guidelines have been developed to distinguish independent non-small cell lung cancers from metastases, that is, criteria developed by Martini and Melamed and the American College of Chest Physicians (ACCP). However, these guidelines can be difficult to apply and may give conflicting results. Here, we report on seven patients in whom epidermal growth factor receptor (EGFR) and Kirsten-rat sarcoma 2 viral oncogene homolog (KRAS) tumor mutation status was used to determine clonal relationships among multiple lung lesions.

    Methods: We identified seven patients whose paired lung adenocarcinomas were found to harbor distinct EGFR or KRAS mutations. We assessed these patients' disease status using established clinical guidelines. We also explored the use of comprehensive histologic subtyping (CHS) of tumor sections to distinguish multiple primaries.

    Results: According to the Martini-Melamed criteria, six of the seven patients had multiple primary lung tumors. By ACCP criteria, three patients had multiple primaries, and three patients had metastases. Classification of the seventh patient by ACCP criteria was indeterminate. Mutational testing suggested that all paired tumors were multiple primary adenocarcinomas, which was consistent with results from CHS.

    Conclusions: Assuming that independent tumor clones harbor distinct mutations, these seven cases highlight discrepancies between the existing clinical criteria used to distinguish independent tumor foci from metastases. EGFR/KRAS mutation testing of multiple lung adenocarcinomas can assist in differentiating multiple primary lung adenocarcinomas from metastatic lesions. Use of CHS in this setting should also be further explored.

    Chest 2010;137;1;46-52

  • Phase II study of preoperative gefitinib in clinical stage I non-small-cell lung cancer.

    Lara-Guerra H, Waddell TK, Salvarrey MA, Joshua AM, Chung CT, Paul N, Boerner S, Sakurada A, Ludkovski O, Ma C, Squire J, Liu G, Shepherd FA, Tsao MS and Leighl NB

    University Ave, Toronto, Ontario, Canada M5G 2M9.

    Purpose: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have proven efficacy in advanced non-small-cell lung cancer (NSCLC). Their role in early-stage NSCLC has not been established. Our purpose was to explore the use of preoperative gefitinib in clinical stage I NSCLC to assess tumor response, toxicity, and clinical and molecular predictors of response.

    Patients received gefitinib 250 mg/d for up to 28 days, followed by mediastinoscopy and surgical resection in an open-label, single-arm study. Tumor response was evaluated by Response Evaluation Criteria in Solid Tumors. Blood samples and tumor biopsies were collected and analyzed for transforming growth factor alpha level, EGFR protein expression, EGFR gene copy number, and EGFR (exon 19 to 21) and KRAS mutations.

    Results: Thirty-six patients completed preoperative treatment (median duration, 28 days; range, 27 to 30 days). Median follow-up time is 2.1 years (range, 0.86 to 3.46 years). Three patients experienced grade 3 toxicities (rash, diarrhea, and elevated ALT). Tumors demonstrated EGFR-positive protein expression in 83%, high gene copy number in 59%, EGFR mutations in 17%, and KRAS mutations in 17%. Tumor shrinkage was more frequent among women and nonsmokers. Partial response was seen in four patients (11%), and disease progression was seen in three patients (9%). The strongest predictor of response was EGFR mutation.

    Conclusion: Preoperative window therapy with gefitinib is a safe and feasible regimen in early NSCLC and provides a trial design that may better inform predictors of treatment response or sensitivity.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2009;27;36;6229-36

  • Analysis of PTEN, BRAF, and EGFR status in determining benefit from cetuximab therapy in wild-type KRAS metastatic colon cancer.

    Laurent-Puig P, Cayre A, Manceau G, Buc E, Bachet JB, Lecomte T, Rougier P, Lievre A, Landi B, Boige V, Ducreux M, Ychou M, Bibeau F, Bouché O, Reid J, Stone S and Penault-Llorca F

    INSERM UMR-S775 Molecular Basis of Xenobiotics Response, Paris, France. pierre.laurent-puig@parisdescartes.fr

    Purpose: The occurrence of KRAS mutation is predictive of nonresponse and shorter survival in patients treated by anti-epidermal growth factor receptor (anti-EGFR) antibody for metastatic colorectal cancer (mCRC), leading the European Medicine Agency to limit its use to patients with wild-type KRAS tumors. However, only half of these patients will benefit from treatment, suggesting the need to identify additional biomarkers for cetuximab-based treatment efficacy.

    We retrospectively collected tumors from 173 patients with mCRC. All but one patient received a cetuximab-based regimen as second-line or greater therapy. KRAS and BRAF status were assessed by allelic discrimination. EGFR amplification was assessed by chromogenic in situ hybridization and fluorescent in situ hybridization, and the expression of PTEN was assessed by immunochemistry.

    Results: In patients with KRAS wild-type tumors (n = 116), BRAF mutations (n = 5) were weakly associated with lack of response (P = .063) but were strongly associated with shorter progression-free survival (P < .001) and shorter overall survival (OS; P < .001). A high EGFR polysomy or an EGFR amplification was found in 17.7% of the patients and was associated with response (P = .015). PTEN null expression was found in 19.9% of the patients and was associated with shorter OS (P = .013). In multivariate analysis, BRAF mutation and PTEN expression status were associated with OS.

    Conclusion: BRAF status, EGFR amplification, and cytoplasmic expression of PTEN were associated with outcome measures in KRAS wild-type patients treated with a cetuximab-based regimen. Subsequent studies in clinical trial cohorts will be required to confirm the clinical utility of these markers.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2009;27;35;5924-30

  • KRAS and BRAF mutations in advanced colorectal cancer are associated with poor prognosis but do not preclude benefit from oxaliplatin or irinotecan: results from the MRC FOCUS trial.

    Richman SD, Seymour MT, Chambers P, Elliott F, Daly CL, Meade AM, Taylor G, Barrett JH and Quirke P

    Leeds Institute of Molecular Medicine, St. James's Institute of Oncology, Cancer Research UK Genomic Services, University of Leeds, Leeds, UK.

    Purpose: Activating mutation of the KRAS oncogene is an established predictive biomarker for resistance to anti-epidermal growth factor receptor (anti-EGFR) therapies in advanced colorectal cancer (aCRC). We wanted to determine whether KRAS and/or BRAF mutation is also a predictive biomarker for other aCRC therapies.

    The Medical Research Council Fluorouracil, Oxaliplatin and Irinotecan: Use and Sequencing (MRC FOCUS) trial compared treatment sequences including first-line fluorouracil (FU), FU/irinotecan or FU/oxaliplatin in aCRC. Tumor blocks were obtained from 711 consenting patients. DNA was extracted and KRAS codons 12, 13, and 61 and BRAF codon 600 were assessed by pyrosequencing. Mutation (mut) status was assessed first as a prognostic factor and then as a predictive biomarker for the benefit of adding irinotecan or oxaliplatin to FU. The association of BRAF-mut with loss of MLH1 was assessed by immunohistochemistry.

    Results: Three hundred eight (43.3%) of 711 patients had KRAS-mut and 56 (7.9%) of 711 had BRAF-mut. Mutation of KRAS, BRAF, or both was present in 360 (50.6%) of 711 patients. Mutation in either KRAS or BRAF was a poor prognostic factor for overall survival (OS; hazard ratio [HR], 1.40; 95% CI, 1.20 to 1.65; P < .0001) but had minimal impact on progression-free survival (PFS; HR, 1.16; 95% CI, 1.00 to 1.36; P = .05). Mutation status did not affect the impact of irinotecan or oxaliplatin on PFS or OS. BRAF-mut was weakly associated with loss of MLH1 staining (P = .012).

    Conclusion: KRAS/BRAF mutation is associated with poor prognosis but is not a predictive biomarker for irinotecan or oxaliplatin. There is no evidence that patients with KRAS/BRAF mutated tumors are less likely to benefit from these standard chemotherapy agents.

    Funded by: Cancer Research UK; Medical Research Council

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2009;27;35;5931-7

  • Fulfilling the promise of personalized medicine? Systematic review and field synopsis of pharmacogenetic studies.

    Holmes MV, Shah T, Vickery C, Smeeth L, Hingorani AD and Casas JP

    Centre for Clinical Pharmacology, University College London, London, United Kingdom.

    Background: Studies of the genetic basis of drug response could help clarify mechanisms of drug action/metabolism, and facilitate development of genotype-based predictive tests of efficacy or toxicity (pharmacogenetics).

    Objectives: We conducted a systematic review and field synopsis of pharmacogenetic studies to quantify the scope and quality of available evidence in this field in order to inform future research.

    Original research articles were identified in Medline, reference lists from 24 meta-analyses/systematic reviews/review articles and U.S. Food and Drug Administration website of approved pharmacogenetic tests. STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTION CRITERIA: We included any study in which either intended or adverse response to drug therapy was examined in relation to genetic variation in the germline or cancer cells in humans.

    Study characteristics and data reported in abstracts were recorded. We further analysed full text from a random 10% subset of articles spanning the different subclasses of study.

    Results: From 102,264 Medline hits and 1,641 articles from other sources, we identified 1,668 primary research articles (1987 to 2007, inclusive). A high proportion of remaining articles were reviews/commentaries (ratio of reviews to primary research approximately 25 ratio 1). The majority of studies (81.8%) were set in Europe and North America focussing on cancer, cardiovascular disease and neurology/psychiatry. There was predominantly a candidate gene approach using common alleles, which despite small sample sizes (median 93 [IQR 40-222]) with no trend to an increase over time, generated a high proportion (74.5%) of nominally significant (p<0.05) reported associations suggesting the possibility of significance-chasing bias. Despite 136 examples of gene/drug interventions being the subject of >or=4 studies, only 31 meta-analyses were identified. The majority (69.4%) of end-points were continuous and likely surrogate rather than hard (binary) clinical end-points.

    The high expectation but limited translation of pharmacogenetic research thus far may be explained by the preponderance of reviews over primary research, small sample sizes, a mainly candidate gene approach, surrogate markers, an excess of nominally positive to truly positive associations and paucity of meta-analyses. Recommendations based on these findings should inform future study design to help realise the goal of personalised medicines. SYSTEMATIC REVIEW REGISTRATION NUMBER: Not Registered.

    Funded by: British Heart Foundation: FS 05/125; Medical Research Council: G0802432; Wellcome Trust: 082178

    PloS one 2009;4;12;e7960

  • KRAS mutation in stage III colon cancer and clinical outcome following intergroup trial CALGB 89803.

    Ogino S, Meyerhardt JA, Irahara N, Niedzwiecki D, Hollis D, Saltz LB, Mayer RJ, Schaefer P, Whittom R, Hantel A, Benson AB, Goldberg RM, Bertagnolli MM, Fuchs CS, Cancer and Leukemia Group B, North Central Cancer Treatment Group, Canadian Cancer Society Research Institute and Southwest Oncology Group

    Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115, USA. shuji_ogino@dfci.harvard.edu

    Purpose: Alterations in the RAS and RAF pathway relate to epigenetic and epigenomic aberrations, and are important in colorectal carcinogenesis. KRAS mutation in metastatic colorectal cancer predicts resistance to anti-epidermal growth factor receptor (EGFR)-targeted therapy (cetuximab or panitumumab). It remains uncertain, however, whether KRAS mutation predicts prognosis or clinical outcome of colon cancer patients independent of anti-EGFR therapy. Methods: We conducted a study of 508 cases identified among 1,264 patients with stage III colon cancer who enrolled in a randomized adjuvant chemotherapy trial (5-fluorouracil, leucovorin with or without irinotecan) in 1999-2001 (CALGB 89803). KRAS mutations were detected in 178 tumors (35%) by pyrosequencing. Kaplan-Meier and Cox proportional hazard models assessed the prognostic significance of KRAS mutation and adjusted for potential confounders including age, sex, tumor location, tumor/node stage, performance status, adjuvant chemotherapy arm, and microsatellite instability status.

    Results: Compared with patients with KRAS-wild-type tumors, patients with KRAS-mutated tumors did not experience any difference in disease-free, recurrence-free, or overall survival. The 5-year disease-free, recurrence-free, and overall survival rates (KRAS-mutated versus KRAS-wild-type patients) were 62% versus 63% (log-rank P = 0.89), 64% versus 66% (P = 0.84), and 75% versus 73% (P = 0.56), respectively. The effect of KRAS mutation on patient survival did not significantly differ according to clinical features, chemotherapy arm, or microsatellite instability status, and the effect of adjuvant chemotherapy assignment on outcome did not differ according to KRAS status.

    Conclusions: In this large trial of chemotherapy in stage III colon cancer patients, KRAS mutational status was not associated with any significant influence on disease-free or overall survival.

    Funded by: NCI NIH HHS: CA31946, CA33601, K07 CA122826, K07 CA122826-01A1, K07 CA122826-02, K07 CA122826-03, P50 CA127003, P50 CA127003-01, R01 CA118553-01A2, R01 CA118553-02, R01 CA118553-03, U10 CA023318-27, U10 CA031946-24, U10 CA032291-22, U10 CA033601-25, U10 CA035415-20, U10 CA038926, U10 CA038926-18, U10 CA046282-15, U10 CA077651-07

    Clinical cancer research : an official journal of the American Association for Cancer Research 2009;15;23;7322-9

  • Novel multiple, monoallelic KRAS mutations at codon 12 and 13.

    Keller G, Geist B, Slotta-Huspenina J, Langer R, Nagl F, Fend F, Höfler H and Perren A

    International journal of cancer 2009;125;11;2744-5

  • Detection of EGFR and KRAS mutations on trans-thoracic needle aspiration of lung nodules by high resolution melting analysis.

    Fassina A, Gazziero A, Zardo D, Corradin M, Aldighieri E and Rossi GP

    Department of Diagnostic Medical Sciences and Special Therapies, Pathology Section, School of Medicine, University of Padova, 35100 Padova, Italy. ambrogio.fassina@unipd.it

    Background: EGFR and KRAS are the target genes for tumour response to epidermal growth factor receptor (EGFR) inhibitors.

    Aims: To investigate EGFR and KRAS mutational status with high resolution melting (HRM) analysis applied to cytological material obtained from trans-thoracic needle aspiration (TTNA) in order to better select patients for targeted therapy.

    Methods: DNA was extracted from fixed material of 108 TTNAs under CT guidance, from 108 consecutive patients. In 77 TTNAs (71.3.%) that were positive for non-small cell lung cancer, the variant in exon 21 (the missense mutation at codon 858, L858R) and the deletion in exon 19 (in frame deletion at codons 747-749) of the EGFR gene, and the point mutation in exon 2 of KRAS were investigated with HRM assay using sequencing as the reference "gold standard".

    Results: Nine (11.7%) samples were positive for KRAS exon 2 mutations, and two (2.6%) samples were positive for the EGFR exon 21 missense mutation by HRM assay. No deletion at exon 19 for EGFR was detected by HRM analysis. All HRM results were confirmed by direct DNA sequencing.

    Conclusions: HRM analysis of cytological material was accurate for the detection of two major EGFR mutations and KRAS mutations in exon 2. HRM analysis was fast, easy to apply, cheap, highly reproducible, and could be used with small amounts of material, such as is obtainable with needle lavage. Therefore, it may be useful as an adjunct to the cytological report that yields valuable molecular information.

    Journal of clinical pathology 2009;62;12;1096-102

  • K-ras status in squamous cell anal carcinoma (SCC): it's time for target-oriented treatment?

    Zampino MG, Magni E, Sonzogni A and Renne G

    Medical Care Unit, Department of Medicine, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy. maria.zampino@ieo.it

    Purpose: Squamous cell anal carcinoma (SCC) is an uncommon disease comprising only 1-5% of all intestinal tumours. SCC is now considered the prototype for the successful application of conservative treatment as chemoradiation instead of aggressive surgery. The EGFR status and k-ras mutations in SCC of the anal canal has not been well investigated. The purpose of our evaluation was to give information about this issue.

    Methods: From June 1999 to December 2008, 32 patients affected by SCC were treated in our institution with chemotherapy containing Fluoropyrimidine and platinum salt concomitant with pelvic radiotherapy. Immunohistochemistry for EGFR and k-ras mutation was retrospectively evaluated.

    Results: Twenty-six specimens were considered evaluable for biological objectives: K-ras mutation was performed in all cases, while EGFR in 12. In all cases of our series wild-type K-ras was observed.

    Conclusions: Such information is, in our knowledge, the Wrst reported in literature on this setting. This observation previously reported in other tumours has supported the effective use of EGFR-inhibitors in recurrent or metastatic disease. This observation could support the role of EGFR-inhibitors in the treatment of SCC.

    Cancer chemotherapy and pharmacology 2009;65;1;197-9

  • MGMT methylation is associated primarily with the germline C>T SNP (rs16906252) in colorectal cancer and normal colonic mucosa.

    Hawkins NJ, Lee JH, Wong JJ, Kwok CT, Ward RL and Hitchins MP

    School of Medical Sciences, University of NSW, Sydney, Australia.

    O(6)-methylguanine DNA methyltransferase (MGMT) is a DNA repair protein that restores mutagenic O(6)-methylguanine to guanine. MGMT methylation is frequently observed in sporadic colorectal cancer and was recently correlated with the C>T allele at SNP rs16906252, within the transcriptional enhancer element of the promoter. MGMT methylation has also been associated with KRAS mutations, particularly G>A transitions. We studied 1123 colorectal carcinoma to define the molecular and clinicopathological profiles associated with MGMT methylation. Furthermore, we assessed factors contributing to MGMT methylation in the development of colorectal cancer by studying the allelic pattern of MGMT methylation using SNP rs16906252, and the methylation status of neighbouring genes within 10q26 in selected tumours and matched normal colonic mucosa. MGMT methylation was detected by combined bisulphite restriction analysis in 28% of tumours and was associated with a number of characteristics, including CDKN2A methylation, absent lymphovascular space invasion and KRAS mutations (but not specifically with KRAS G>A transitions). In a multivariate analysis adjusted for age and sex, MGMT methylation was associated with the T allele of SNP rs16906252 (P<0.0001, OR 5.5, 95% CI 3.8-7.9). Low-level methylation was detected by quantitative methylation-specific PCR in the normal colonic mucosa of cases, particularly those with a correspondingly methylated tumour, as well as controls without neoplasia, and this was also associated with the C>T SNP. We show that the T allele at SNP rs16906252 is a key determinant in the onset of MGMT methylation in colorectal cancer, whereas the association of methylation at MGMT and CDKN2A suggests that these loci may be targets of a common mechanism of epigenetic dysregulation.

    Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc 2009;22;12;1588-99

  • PTEN identified as important risk factor of chronic obstructive pulmonary disease.

    Hosgood HD, Menashe I, He X, Chanock S and Lan Q

    Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA.

    Common genetic variation may play an important role in altering chronic obstructive pulmonary disease (COPD) risk. In Xuanwei, China, the COPD rate is more than twice the Chinese national average, and COPD is strongly associated with in-home coal use. To identify genetic variation that may be associated with COPD in a population with substantial in-home coal smoke exposures, we evaluated 1261 single nucleotide polymorphisms (SNPs) in 380 candidate genes potentially relevant for cancer and other human diseases in a population-based case-control study in Xuanwei (53 cases; 107 controls). PTEN was the most significantly associated gene with COPD in a minP analysis using 20,000 permutations (P=0.00005). SNP-based analyses found that homozygote variant carriers of PTEN rs701848 (OR(TT)=0.12, 95% CI=0.03-0.47) had a significant decreased risk of COPD. PTEN, or phosphatase and tensin homolog, is an important regulator of cell cycle progression and cellular survival via the AKT signaling pathway. Our exploratory analysis suggests that genetic variation in PTEN may be an important risk factor of COPD in Xuanwei. However, due to the small sample size, additional studies are needed to evaluate these associations within Xuanwei and other populations with coal smoke exposures.

    Funded by: Intramural NIH HHS: Z99 CA999999

    Respiratory medicine 2009;103;12;1866-70

  • Significant association between EGFR-mutated lung adenocarcinoma and past illness from gastric cancer or uterine myoma: its implication in carcinogenesis.

    Okudela K, Woo T, Yazawa T, Ogawa N, Tajiri M, Masuda M and Kitamura H

    Department of Pathology, Yokohama City University Graduate School of Medicine, 3-9, Fukuura, Kanazawa-ku, 236-0004, Yokohama, Japan.

    The present study investigated the potential difference between EGFR-mutated lung adenocarcinoma (ADC) and KRAS-mutated ADC in relation to past illness and family history. Among the 153 tumors examined, 33 (21.6%) were EGFR-mutated, and 22 (14.4%) were KRAS-mutated. The EGFR-mutated cases showed a significantly higher prevalence of past illness involving the gastric cancer in males (EGFR 3/8 (37.5%), KRAS 0/13 (0.0%), no mutation (NONE) 1/57 (1.8%); Fisher's exact test, P=0.0064) or uterine myoma in females (EGFR 8/25 (32.0%), KRAS 0/9 (0.0%), NONE 3/41 (7.3%); Fisher's exact test, P=0.0139). No association between the mutations and family history was found. The EGFR-mutated ADC is therefore likely to develop through a distinct carcinogenetic pathway from the others, but genetic backgrounds seemed unlikely to be determinant predisposing to the EGFR-mutated ADC.

    Lung cancer (Amsterdam, Netherlands) 2009;66;3;287-91

  • The mechanisms underlying MMR deficiency in immunodeficiency-related non-Hodgkin lymphomas are different from those in other sporadic microsatellite instable neoplasms.

    Borie C, Colas C, Dartigues P, Lazure T, Rince P, Buhard O, Folliot P, Chalastanis A, Muleris M, Hamelin R, Mercier D, Oliveira C, Seruca R, Chadburn A, Leblond V, Barete S, Gaïdano G, Martin A, Gaulard P, Fléjou JF, Raphael M and Duval A

    INSERM, UMR_S 938, Team Microsatellite Instability and Cancers, Paris, France.

    The spectrum of tumors showing microsatellite instability (MSI) has recently been enlarged to sporadic neoplasms whose incidence is favored in the context of chronic immunosuppression. We investigated the biological, therapeutic and clinical features associated with MSI in immunodeficiency-related non-Hodgkin lymphomas (ID-RL). MSI screening was performed in 275 ID-RL. MSI ID-RL were further analyzed for MMR gene expression and for BRAF/KRAS mutations since these genes are frequently altered in MSI cancers. We also assessed the expression of O(6)-methylguanine-DNA methyltransferase (MGMT), an enzyme whose inactivation has been reported in lymphomas and may help in the selection of MMR deficient clones. Unlike other sporadic MSI neoplasms, MSI ID-RL (N = 17) presented with heterogeneous MMR defects and no MLH1 promoter methylation. About one third of these tumors presented with normal expression of MLH1, MSH2, MSH6 and PMS2. They accumulated BRAF activating mutations (33%). Unlike other ID-RL, MSI ID-RL were primarily EBV-negative NHL of T-cell origin, and arose after long-term immunosuppression in patients who received azathioprine as part of their immunosuppressive regimen (p = 0.05) and/or who exhibited methylation-induced loss of expression of MGMT in tumor cells (p= 0.02). Overall, these results highlight that, in the context of deficient immune status, some MSI neoplasms arise through alternative mechanism when compared to other sporadic MSI neoplasms. They give the exact way how to make the diagnosis of MSI in these tumors and may help to define biological and clinicalrisk factors associated with their emergence in such a clinicalcontext.

    International journal of cancer 2009;125;10;2360-6

  • EGFR and KRAS status of primary sarcomatoid carcinomas of the lung: implications for anti-EGFR treatment of a rare lung malignancy.

    Italiano A, Cortot AB, Ilie M, Martel-Planche G, Fabas T, Pop D, Mouroux J, Hofman V, Hofman P and Pedeutour F

    Laboratory of Solid Tumors Genetics, Nice University Hospital, Nice, France.

    Sarcomatoid carcinomas (SC) of the lung are uncommon malignant tumors composed of carcinomatous and sarcomatous cell components and characterized by a more aggressive outcome than other histological subtypes of nonsmall cell lung cancer (NSCLC). Although epidermal growth factor receptor (EGFR)-targeted therapies have emerged as a promising therapeutic approach in patients with advanced typical NSCLC such as adenocarcinoma, the potential clinical activity of these drugs in lung SC is still unknown. To investigate this point, we have analyzed the status of 4 EGFR pathways biomarkers in a series of lung SC. EGFR protein expression, EGFR gene copy number, EGFR mutational status and KRAS mutational status were assessed in a series of 22 consecutive cases of primary lung SC. EGFR protein overexpression was observed in all the cases. High level of polysomy (>or=4 copies of the gene in >40% of cells) was detected in 5 cases (23%). No EGFR mutation was detected. KRAS mutations were found in 8 patients (38%; Gly12Cys in 6 cases and Gly12Val in 2 cases). The consistent EGFR protein overexpression and the high rate of KRAS mutation may contribute to the poorer outcome of lung SC in comparison with typical NSCLC. The rare incidence of increased EGFR gene copy number, the lack of EGFR mutation and the high rate of KRAS mutation observed in our series also suggest that most patients with lung SC are not likely to benefit from anti-EGFR therapies.

    International journal of cancer 2009;125;10;2479-82

  • PIK3CA mutations predict local recurrences in rectal cancer patients.

    He Y, Van't Veer LJ, Mikolajewska-Hanclich I, van Velthuysen ML, Zeestraten EC, Nagtegaal ID, van de Velde CJ and Marijnen CA

    Departments of Experimental Therapy, Pathology, and Radiotherapy, Netherlands Cancer Institute, Amsterdam, the Netherlands.

    Purpose: Identifying rectal cancer patients at risk for local recurrence would allow for refinement in the selection of patients who would benefit from preoperative radiotherapy. PIK3CA, KRAS, and BRAF mutations are commonly found in colon cancers, but their prevalence has not been clearly assessed in rectal cancer. In this study, we aim to determine the mutation frequencies of PIK3CA, KRAS, and BRAF and to investigate whether a mutation may be used as a prognostic parameter in rectal cancer patients.

    We evaluated DNA mutations in PIK3CA, KRAS, and BRAF in 240 stage I to III rectal tumors obtained from nonirradiated patients from the Dutch Total Mesorectal Excision trial.

    Results: PIK3CA, KRAS, and BRAF mutations were identified in 19 (7.9%), 81 (33.9%), and 5 (2.1%) rectal cancers. Patients with PIK3CA mutations developed more local recurrences (5-year risks, 27.8% versus 9.4%; P = 0.006) and tended to develop these recurrences more rapidly after surgery (median local recurrence-free interval since surgery: 7.9 versus 19.6 months; P = 0.07) than patients without PIK3CA mutations. In multivariate analysis, PIK3CA mutations remained as an independent predictor for the development of local recurrences (hazard ratio, 3.4; 95% confidence interval, 1.2-9.2; P = 0.017), next to tumor-node-metastasis stage.

    Conclusion: PIK3CA mutations can be used as a biomarker in identifying rectal cancer patients with an increased risk for local recurrences. Currently, our findings suggest that prospective evaluation of PIK3CA mutation status could reduce overtreatment by preoperative radiotherapy for the low-risk patients who might otherwise only experience the side effects.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2009;15;22;6956-62

  • Systematic RNA interference reveals that oncogenic KRAS-driven cancers require TBK1.

    Barbie DA, Tamayo P, Boehm JS, Kim SY, Moody SE, Dunn IF, Schinzel AC, Sandy P, Meylan E, Scholl C, Fröhling S, Chan EM, Sos ML, Michel K, Mermel C, Silver SJ, Weir BA, Reiling JH, Sheng Q, Gupta PB, Wadlow RC, Le H, Hoersch S, Wittner BS, Ramaswamy S, Livingston DM, Sabatini DM, Meyerson M, Thomas RK, Lander ES, Mesirov JP, Root DE, Gilliland DG, Jacks T and Hahn WC

    Department of Medical Oncology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, Massachusetts 02115 USA.

    The proto-oncogene KRAS is mutated in a wide array of human cancers, most of which are aggressive and respond poorly to standard therapies. Although the identification of specific oncogenes has led to the development of clinically effective, molecularly targeted therapies in some cases, KRAS has remained refractory to this approach. A complementary strategy for targeting KRAS is to identify gene products that, when inhibited, result in cell death only in the presence of an oncogenic allele. Here we have used systematic RNA interference to detect synthetic lethal partners of oncogenic KRAS and found that the non-canonical IkappaB kinase TBK1 was selectively essential in cells that contain mutant KRAS. Suppression of TBK1 induced apoptosis specifically in human cancer cell lines that depend on oncogenic KRAS expression. In these cells, TBK1 activated NF-kappaB anti-apoptotic signals involving c-Rel and BCL-XL (also known as BCL2L1) that were essential for survival, providing mechanistic insights into this synthetic lethal interaction. These observations indicate that TBK1 and NF-kappaB signalling are essential in KRAS mutant tumours, and establish a general approach for the rational identification of co-dependent pathways in cancer.

    Funded by: NCI NIH HHS: R01 CA129105, R01 CA129105-03, R01 CA130988, R01 CA130988-01A2, R33 CA128625, R33 CA128625-01A1, R33 CA128625-02, T32 CA009172, T32 CA09172-33; NIGMS NIH HHS: T32 GM007753

    Nature 2009;462;7269;108-12

  • Oncogenic KRAS and BRAF differentially regulate hypoxia-inducible factor-1alpha and -2alpha in colon cancer.

    Kikuchi H, Pino MS, Zeng M, Shirasawa S and Chung DC

    Gastrointestinal Unit and Cancer Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.

    KRAS and BRAF mutations are frequently observed in human colon cancers. These mutations occur in a mutually exclusive manner, and each is associated with distinctive biological features. We showed previously that K-ras can interact with hypoxia to activate multiple signaling pathways. Many hypoxic responses are mediated by hypoxia-inducible factor (HIF)-1alpha and HIF-2alpha, and we sought to define the roles of mutant KRAS and BRAF in the induction of HIF-1alpha and HIF-2alpha in colon cancer cells. Ectopic expression of mutant K-ras in Caco2 cells enhanced the hypoxic induction of only HIF-1alpha, whereas mutant BRAF enhanced both HIF-1alpha and HIF-2alpha. Knockout or knockdown of mutant KRAS in DLD-1 and HCT116 cells impaired the hypoxic induction of only HIF-1alpha. HIF-1alpha mRNA levels were comparable in cells with and without a KRAS mutation. However, the rate of HIF-1alpha protein synthesis was higher in cells with a KRAS mutation, and this was suppressed by the phosphoinositide 3-kinase inhibitor LY294002. In contrast, knockdown of mutant BRAF in HT29 cells suppressed both HIF-1alpha and HIF-2alpha. Although BRAF regulated mRNA levels of both HIF-1alpha and HIF-2alpha, knockdown of BRAF or treatment with the MEK inhibitor PD98059 impaired the translation of only HIF-2alpha. Our data reveal that oncogenic KRAS and BRAF mutations differentially regulate the hypoxic induction of HIF-1alpha and HIF-2alpha in colon cancer, and this may potentially contribute to the phenotypic differences of KRAS and BRAF mutations in colon tumors.

    Funded by: NCI NIH HHS: CA92594, R01 CA092594-08

    Cancer research 2009;69;21;8499-506

  • TRAIL receptor upregulation and the implication of KRAS/BRAF mutations in human colon cancer tumors.

    Oikonomou E, Kosmidou V, Katseli A, Kothonidis K, Mourtzoukou D, Kontogeorgos G, Andera L, Zografos G and Pintzas A

    Laboratory of Signal Mediated Gene Expression, Institute of Biological Research and Biotechnology, National Hellenic Research Foundation, Athens, Greece.

    TRAIL raises hopes as a promising anti-tumor agent due to its selectivity toward cancer cells. Higher expression of its pro-death receptors TRAIL-R1 (DR4) and TRAIL-R2 (DR5) attenuates higher sensitivity to TRAIL-induced apoptosis, and represents a marker for better cancer prognosis and treatment. Since receptor availability can be analogous to ligand efficacy, we performed RT-PCR analysis of DR4 and DR5 in 51 colon cancer biopsy specimens and respective normal mucosa, while 11 of these tumors were determined immunohistochemically for protein expression. Transcriptional analysis showed that DR4 and DR5 were significantly upregulated in 37 and 47% of the tumor samples respectively, while both DR4 and DR5 were coinstantaneously upregulated in 31% of the samples analyzed. Positive transcriptional regulation of DRs was recorded as early as Dukes' A stage. Furthermore, protein expression analysis yielded results comparable to DR4 and DR5 increased mRNA levels. Possible contributing events to DR upregulation involve presence of frequent oncogenic mutations in the MAPK pathway, and was investigated by direct sequencing in all 51 tumors. Samples (6/8) hosting either a KRAS(G12V) or BRAF(V600E) mutation, significantly amplified the upregulated expression of DR4 and DR5, showing strong inter-relation between overexpression and presence of oncogenic KRAS/ BRAF mutations. In the light of recent data concerning TRAIL receptor distribution, we contribute further by presenting DR5 as the most frequently upregulated DR in colon cancer. Furthermore, oncogenic mutations may directly or indirectly enhance DR expression, potentially sensitizing these tumors to TRAIL-based therapies.

    International journal of cancer. Journal international du cancer 2009;125;9;2127-35

  • A multicenter blinded study to evaluate KRAS mutation testing methodologies in the clinical setting.

    Whitehall V, Tran K, Umapathy A, Grieu F, Hewitt C, Evans TJ, Ismail T, Li WQ, Collins P, Ravetto P, Leggett B, Salto-Tellez M, Soong R, Fox S, Scott RJ, Dobrovic A and Iacopetta B

    Queensland Institute of Medical Research, Bancroft Building, 300 Herston Road, Herston Queensland 4029, Australia. Vicki.Whitehall@qimr.edu.au

    Evidence that activating mutations of the KRAS oncogene abolish the response to anti-epidermal growth factor receptor therapy has revolutionized the treatment of advanced colorectal cancer. This has resulted in the urgent demand for KRAS mutation testing in the clinical setting to aid choice of therapy. The aim of this study was to evaluate six different KRAS mutation detection methodologies on two series of primary colorectal cancer samples. Two series of 80 frozen and 74 formalin-fixed paraffin-embedded tissue samples were sourced and DNA was extracted at a central site before distribution to seven different testing sites. KRAS mutations in codons 12 and 13 were assessed by using single strand conformation polymorphism analysis, pyrosequencing, high resolution melting analysis, dideoxy sequencing, or the commercially available TIB Molbiol (Berlin, Germany) or DxS Diagnostic Innovations (Manchester, UK) kits. In frozen tissue samples, concordance in KRAS status (defined as consensus in at least five assays) was observed in 66/80 (83%) cases. In paraffin tissue, concordance was 46/74 (63%) if all assays were considered or 71/74 (96%) using the five best performing assays. These results demonstrate that a variety of detection methodologies are suitable and provide comparable results for KRAS mutation analysis of clinical samples.

    The Journal of molecular diagnostics : JMD 2009;11;6;543-52

  • A prospective cohort study shows unique epigenetic, genetic, and prognostic features of synchronous colorectal cancers.

    Nosho K, Kure S, Irahara N, Shima K, Baba Y, Spiegelman D, Meyerhardt JA, Giovannucci EL, Fuchs CS and Ogino S

    Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115, USA.

    Synchronous colorectal neoplasias (2 or more primary carcinomas identified in the same patient) are caused by common genetic and environmental factors and can be used to study the field effect. Synchronous colon cancers have not been compared with control solitary cancers in a prospective study.

    Methods: We analyzed data collected from 47 patients with synchronous colorectal cancers and 2021 solitary colorectal cancers (controls) in 2 prospective cohort studies. Tumors samples were analyzed for methylation in LINE-1 and 16 CpG islands (CACNA1G, CDKN2A [p16], CRABP1, IGF2, MLH1, NEUROG1, RUNX3, SOCS1, CHFR, HIC1, IGFBP3, MGMT, MINT1, MINT31, p14 [ARF], and WRN); microsatellite instability (MSI); the CpG island methylator phenotype (CIMP); 18q loss of heterozygosity; KRAS, BRAF, and PIK3CA mutations; and expression of beta-catenin, p53, p21, p27, cyclin D1, fatty acid synthase, and cyclooxygenase-2.

    Results: Compared with patients with solitary colorectal cancer, synchronous colorectal cancer patients had reduced overall survival time (log-rank, P = .0048; hazard ratio [HR], 1.71; 95% confidence interval [CI]: 1.17-2.50; P = .0053; multivariate HR, 1.47; 95% CI: 1.00-2.17; P = .049). Compared with solitary tumors, synchronous tumors more frequently contained BRAF mutations (P = .0041), CIMP-high (P = .013), and MSI-high (P = .037). Methylation levels of LINE-1 (Spearman r = 0.82; P = .0072) and CpG island methylation (P < .0001) correlated between synchronous cancer pairs from the same individuals.

    Conclusions: Synchronous colorectal cancers had more frequent mutations in BRAF, were more frequently CIMP- and MSI-high, and had a worse prognosis than solitary colorectal cancers. Similar epigenomic and epigenetic events were frequently observed within a synchronous cancer pair, suggesting the presence of a field defect.

    Funded by: NCI NIH HHS: K07 CA122826, K07 CA122826-01A1, K07 CA122826-02, K07 CA122826-03, P01 CA055075, P01 CA055075-15, P01 CA087969, P01 CA087969-10, P01 CA55075, P01 CA87969, P50 CA127003, P50 CA127003-03

    Gastroenterology 2009;137;5;1609-20.e1-3

  • The status of KRAS mutations in patients with non-small cell lung cancers from mainland China.

    Li M, Liu L, Liu Z, Yue S, Zhou L, Zhang Q, Cheng S, Li RW, Smith PN and Lu S

    Laboratory Center, Department of Thoracic Surgery, The Second Affiliated Hospital of Dalian Medical University, Dalian 116027, Liaoning Province, PR China.

    KRAS mutation is closely associated to carcinogenesis and prognosis of non-small cell lung cancer (NSCLC). Detection of KRAS mutation can also be used to select NSCLC patients for drug targeting with EGFR tyrosine kinase inhibitors. Data regarding the status of KRAS mutation in mainland China, which would assist in these interventions, is lacking. We have detected KRAS mutation from 103 NSCLC patients in mainland China with high resolution melting analysis (HRM) on LightScanner, and compared this method of detection with sequencing, and found HRM to have greater sensitivity. We found 6 patients (5.8%) with KRAS mutation (3 patients, G12C; 1 patient, G12S; 1 patient, G12V; 1 patient, G13D). KRAS mutation was significantly associated to gender (p=0.027) and pathology types (p=0.000), but not to smoking. The mutation frequency of KRAS in NSCLC patients in mainland China is similar to those in East Asian countries, but lower than those in western countries. However, the spectrum of KRAS mutation in mainland China is similar to those found in the USA. The results also exhibit dependence of KRAS mutation in China on ethnicity. The clinical significance of the spectral pattern of KRAS mutations in TKI resistance or tumorigenesis among patients with NSCLC in mainland China requires further investigation.

    Oncology reports 2009;22;5;1013-20

  • BRAF(V600E) efficient transformation and induction of microsatellite instability versus KRAS(G12V) induction of senescence markers in human colon cancer cells.

    Oikonomou E, Makrodouli E, Evagelidou M, Joyce T, Probert L and Pintzas A

    Laboratory of Signal Mediated Gene Expression, Institute of Biological Research and Biotechnology, National Hellenic Research Foundation, 11635 Athens, Greece.

    In colorectal cancer, BRAF and KRAS oncogenes are mutated in about 15% and 35% respectively at approximately the same stage of the adenoma-carcinoma sequence. Since these two mutations rarely coexist, further analysis to dissect their function of transformation in colon cancer is required. Caco-2 human colon adenocarcinoma cells were stably transfected with BRAF(V600E) (Caco-BR cells) or KRAS(G12V) (Caco-K cells) oncogenes. BRAF(V600E) is more efficient in transforming Caco-2 cells and altering their morphology. The dominant nature of BRAF(V600E) is evident by its ability to render Caco-2 cells tumorigenic in vivo all be it through selective extracellular signal-related kinase (ERK) 2 phosphorylation and high levels of cyclin D1. As a consequence, the cell cycle distribution of parental cells is altered and microsatellite instability is introduced. Attenuated ERK activation observed correlated with KSR downregulation by BRAF(V600E) without further implications to signaling. Highly activated ERK in case of KRAS(G12V) (Caco-K cells) leads to mild transformation causing Caco-K cells to express premature senescence-related markers and acquire growth factor-dependent viability. Interestingly, BRAF(WT)gets equally activated by upstream KRAS mutations present in colon adenocarcinoma cells such as DLD-1 and SW620. Taken together, these results suggest that the two oncogenes have different transforming capability in colon cancer, although they both use the mitogen-activated protein (MAP) kinase pathway to carry out their effect. In general, BRAF(V600E) presents greater potential in mediating tumorigenic effect as compared to KRAS(G12V) both in vivo and in vitro. These findings may have implications in personalised diagnosis and targeted therapeutics.

    Neoplasia (New York, N.Y.) 2009;11;11;1116-31

  • [Effect of KRAS mutation on efficacy of Cetuximab combined with chemotherapy in advanced colorectal cancer patients].

    Pu XX, Deng YH, Xu F, Xiao J, Guo HQ, Huang H, Tian Y, He YJ and Lin TY

    Department of Medical Oncology, Cancer Center, State Key Laboratory of Oncology in Southern China, Sun Yat-sen University, Guangzhou 510060, China.

    Objective: To explore the relationship between KRAS gene status and efficacy of Cetuximab (C225) combined with chemotherapy on advanced colorectal cancer in Chinese patients, and to evaluate the safety of C225.

    Methods: From May 2006 to March 2009, 81 patients with advanced colorectal cancer received Cetuximab combined with chemotherapy were enrolled in this study. The rate of KRAS mutation and the relationship of KRAS with response rate (RR), progression-free survivor (PFS), overall survival (OS) and adverse reaction of C225 were analyzed retrospectively.

    Results: All the 81 patients received C225 therapy, and the overall RR was 33.3%. The RR of initiate therapy was 57.1%; of the second line and over the third line therapy was 38.5% and 22.0% respectively. KRAS gene phenotype examination was performed in 44 patients whose tumor samples were available. KRAS mutation was found in 20 cases (45%). Out of 44 patients, 43 were evaluable for response. RR was 5% and 43.48% in KRAS mutation and wild KRAS patients respectively (P =0.002). The median PFS was 7.0 weeks and 18.6 weeks in mutational KRAS patients and wild KRAS patients, reaching statistical significance (P =0.003). The median OS was 15.2 months and 17.3 months in mutational KRAS patients and wild KRAS patients respectively without statistical significance (P =0.463). The common adverse reactions were leucopenia, nausea, vomiting and rash. All the adverse reactions were tolerated. The incidence of skin rash in patients with mutational KRAS and patients without KRAS mutation was 40% and 42% respectively, without statistical significance (P =0.91).

    Conclusion: C225 combined with chemotherapy is well-tolerated in Chinese patients with advanced colorectal cancer, and it can significantly prolong PFS of patients with wild KRAS as compared to patients with KRAS mutation.

    Zhonghua wei chang wai ke za zhi = Chinese journal of gastrointestinal surgery 2009;12;6;594-7

  • In pancreatic ductal adenocarcinoma blood concentrations of some organochlorine compounds and coffee intake are independently associated with KRAS mutations.

    Porta M, López T, Pumarega J, Jariod M, Crous-Bou M, Marco E, Rifà J, Grimalt JO, Malats N, Real FX and PANKRAS II Study Group

    Institut Municipal d'Investigació Mèdica-Hospital del Mar, E-08003 Barcelona, Catalonia, Spain. mporta@imim.es

    While KRAS activation is a fundamental initiating event in the aetiopathogenesis of pancreatic ductal adenocarcinoma (PDA), environmental factors influencing the occurrence and persistence of KRAS mutations remain largely unknown. The objective was to test the hypothesis that in PDA there are aetiopathogenic relationships among concentrations of some organochlorine compounds (OCs) and the mutational status of the KRAS oncogene, as well as among the latter and coffee intake. Incident cases of PDA were interviewed and had blood drawn at hospital admission (N = 103). OCs were measured by high-resolution gas chromatography with electron capture detection. Cases whose tumours harboured a KRAS mutation had higher concentrations of p,p'-dichlorodiphenyltrichloroethane (DDT), p,p'-dichlorodiphenyldichloroethene (DDE) and polychlorinated biphenyls (PCBs) 138, 153 and 180 than cases with wild-type KRAS, but differences were statistically significant only for p,p'-DDT and PCBs 138 and 153. The association between coffee intake and KRAS mutations remained significant (P-trend < 0.015) when most OCs where accounted for. When p,p'-DDT, PCB 153, coffee and alcohol intake were included in the same model, all were associated with KRAS (P = 0.042, 0.007, 0.016 and 0.025, respectively). p,p'-DDT, p,p'-DDE and PCB 138 were significantly associated with the two most prevalent KRAS mutations (Val and Asp). OCs and coffee may have independent roles in the aetiopathogenesis of PDA through modulation of KRAS activation, acquisition or persistence, plausibly through non-genotoxic or epigenetic mechanisms. Given that KRAS mutations are the most frequent abnormality of oncogenes in human cancers, and the lifelong accumulation of OCs in humans, refutation or replication of the findings is required before any implications are assessed.

    Mutagenesis 2009;24;6;513-21

  • Integrative approach for prioritizing cancer genes in sporadic colon cancer.

    Reid JF, Gariboldi M, Sokolova V, Capobianco P, Lampis A, Perrone F, Signoroni S, Costa A, Leo E, Pilotti S and Pierotti MA

    Department of Experimental Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori Milano, Italy.

    The current multistep carcinogenesis models of colon cancer do not fully capture the genetic heterogeneity of the disease, which is additionally complicated by the presence of passenger and driver genetic alterations. The aim of this study was to select in the context of this significant heterogeneity additional genes functionally related to colon cancer development. High-throughput copy number and gene expression data of 36 microsatellite stable sporadic colon cancers resected from patients of a single institution characterized for mutations in APC, KRAS, TP53 and loss of 18q were analyzed. Genes whose expression correlated with the underlying copy number pattern were selected, and their association with the above listed mutations and overall survival was evaluated. Gain of 20q was strongly associated with TP53 mutation, and overall survival with alterations on 7p, 8p, 13q, 18q, and 20q. An association with 18q loss and gain of 8q24 was also observed. New candidate genes with a potential role in colon cancer are PLCG1 on 20q, DBC1 on 8q21, and NDGR1 on 8p24. In addition, an unexpected pattern of loss and mutability was found in the region upstream of the KRAS gene. By integrating copy number alterations with gene expression and mutations in colon cancer associated genes, we have developed a strategy that identifies previously known molecular features and additional players in the molecular landscape of colon cancer.

    Genes, chromosomes & cancer 2009;48;11;953-62

  • Microsatellite instability and survival in rectal cancer.

    Samowitz WS, Curtin K, Wolff RK, Tripp SR, Caan BJ and Slattery ML

    Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA. wade.samowitz@aruplab.com

    Objective: High levels of microsatellite instability (MSI-H) have been associated in many studies with improved prognosis in colon cancer. Very few studies have evaluated the effect of MSI-H on rectal cancer survival. We assessed MSI-H and other genetic and epigenetic changes on survival of 990 individuals diagnosed with first primary rectal cancer.

    Methods: MSI was assessed primarily by instability in the mononucleotide repeat BAT-26. The BRAF V600E mutation was assessed by TaqMan assay. The CpG island methylator phenotype (CIMP) was determined by methylation-specific PCR of CpG islands in MLH1, methylated in tumors (MINT)1, (MINT)2, (MINT)31 and CDKN2A. KRAS2 codons 12 and 13 mutations, and TP53 mutations in exons 5-8 were determined by sequencing.

    Results: Multivariate analysis revealed that MSI-H (HRR 2.47, 95% CI 1.13-5.40) and KRAS2 mutations (HRR 1.37, 95% CI 1.04-1.81) were associated with a significantly higher risk of dying of rectal cancer. Only one of 22 MSI-H tumors showed a BRAF V600E mutation. Of 15 MSI-H rectal cancers evaluated for methylation, two exhibited MLH1 methylation and four exhibited CIMP.

    Conclusion: The genetic and epigenetic characteristics of MSI-H rectal cancers suggest that they are enriched for Lynch-associated tumors; adverse prognosis associated with MSI-H in these tumors may reflect the relatively high frequency of Lynch-associated cancers and/or the effect of radiation or chemotherapy on Lynch-associated rectal cancers or MSI tumors in general.

    Funded by: NCI NIH HHS: CA61757, N01-PC-67000, R01 CA048998-15, R01 CA061757-11, R01 CA48998

    Cancer causes & control : CCC 2009;20;9;1763-8

  • PI3K/Akt pathway mutations in retinoblastoma.

    Cohen Y, Merhavi-Shoham E, Avraham-Lubin BC, Savetsky M, Frenkel S, Pe'er J and Goldenberg-Cohen N

    Department of Gynecology, Sheba Medical Center, Tel Hashomer, Israel.

    Purpose: Many malignancies are known to be associated with abnormal activation of the PI3K-AKT pathway. Recently, a somatic mutation in the AKT1 gene (E17K) was identified in a small proportion of human tumors. This mutation activated AKT1 by means of abnormal membrane recruitment and stimulated downstream signaling. This study was designed to analyze AKT1 mutations in retinoblastoma and gain insights into the role PI3K-AKT pathway plays in the development of this tumor.

    Methods: Twenty-four samples of retinoblastoma from children were analyzed for mutations in the AKT1, PTEN and K-RAS genes, using a chip-based matrix-assisted laser desorption-time-of-flight (MALDI-TOF) mass spectrometer. Mutations in the PIK3CA gene were analyzed in 16 retinoblastoma samples using direct sequencing.

    Results: These results show that the mutation E17K/AKT1 was not detected in the 24 samples of retinoblastoma analyzed. K-RAS mutations were identified in two samples. There were no mutations in any of the other genes analyzed by a mass array system. On direct sequencing of 16 samples for the PIK3CA gene, one sample showed gain of function mutation in exon 9. In another sample, a genetic polymorphism of unknown significance (rs17849079) was detected in exon 20.

    Conclusions: Although the PI3K-AKT pathway is known to be dysregulated in retinoblastoma, the low frequency of oncogenic mutations in the AKT1, PIK3CA, and PTEN genes, suggests a different activating mechanism.

    Investigative ophthalmology & visual science 2009;50;11;5054-6

  • Ras classical effectors: new tales from in silico complexes.

    Fuentes G and Valencia A

    Structural Computational Biology Group, Spanish National Cancer Research Center (CNIO), C/ Melchor Fernández Almagro, 3, 28029 Madrid, Spain. gfuentes@bii.a-star.edu.sg

    Components of signal transduction pathways have evolved as connected hubs, recognizing several binding partners with remarkable affinities and specificities. Ras is one of these hubs, sensitive to rapid and subtle changes, thus enabling the correct transfer of information. The dynamic nature of such systems makes their structural characterization challenging, despite the vast amount of experimental data available. These data, however, can be used as a restraint for generating comprehensive models of the association of Ras with its effectors. We believe that by following this type of approach, the derived 3D models can provide atomistic understanding of important biological issues, such as how Ras discriminates between the Ras binding domains of its various effectors. The modeled binding interfaces could be used as the starting points for selective modulations of interactions and pathways using small molecules, peptides or mutagenesis.

    Trends in biochemical sciences 2009;34;11;533-9

  • RAS signaling dysregulation in human embryonal Rhabdomyosarcoma.

    Martinelli S, McDowell HP, Vigne SD, Kokai G, Uccini S, Tartaglia M and Dominici C

    Department of Hematology, Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy. simone.martinelli@iss.it

    Rhabdomyosarcoma (RMS) is a common childhood solid tumor, resulting from dysregulation of the skeletal myogenesis program. Two major histological subtypes occur in childhood RMS, embryonal and alveolar. While chromosomal rearrangements account for the majority of alveolar tumors, the genetic defects underlying the pathogenesis of embryonal RMS remain largely undetermined. A few studies performed on small series of embryonal tumors suggest that dysregulation of RAS function may be relevant to disease pathogenesis. To explore further the biological and clinical relevance of mutations with perturbing consequences on RAS signaling in embryonal RMS, we investigated the prevalence of PTPN11, HRAS, KRAS, NRAS, BRAF, MEK1, and MEK2 mutations in a relatively large cohort of primary tumors. While HRAS and KRAS were found to be rarely mutated, we identified somatic NRAS lesions in 20% of cases. All mutations were missense and affected codon 61, with the introduction of a positive charged amino acid residue representing the most common event. PTPN11 was found mutated in one tumor specimen, confirming that somatic defects in this gene are relatively uncommon in RMS, while no mutation was observed in BRAF and MEK genes. Although no clear association of mutations with any clinical variable was observed, comparison of the outcome between mutation-positive and mutation-negative cases indicated a trend for a higher percentage of patients exhibiting a better outcome in the former. Our findings provide evidence that dysregulation of RAS signaling is a major event contributing to embryonal RMS pathogenesis.

    Funded by: Telethon: GGP07115

    Genes, chromosomes & cancer 2009;48;11;975-82

  • Amphiregulin and epiregulin mRNA expression in primary tumors predicts outcome in metastatic colorectal cancer treated with cetuximab.

    Jacobs B, De Roock W, Piessevaux H, Van Oirbeek R, Biesmans B, De Schutter J, Fieuws S, Vandesompele J, Peeters M, Van Laethem JL, Humblet Y, Pénault-Llorca F, De Hertogh G, Laurent-Puig P, Van Cutsem E and Tejpar S

    Department of Pathology, Digestive Oncology Unit, University Hospital Gasthuisberg, Katholieke Universiteit Leuven, Leuven, Belgium.

    Purpose: To study the power of the epidermal growth factor receptor (EGFR) epiregulin (EREG) and amphiregulin (AREG) ligands' expression in primary tumors to predict the outcome in patients with chemorefractory metastatic colorectal cancer (cmCRC) treated with the combination of cetuximab and irinotecan.

    Gene expression measurements and KRAS mutation analysis were performed on archival formalin-fixed paraffin-embedded primary tumors of 220 cmCRC patients. Response was measured using RECIST (Response Evaluation Criteria in Solid Tumors) criteria. The relation between ligand expression levels and outcome was evaluated using logistic regression for response and Cox regression for survival data. Receiver operating characteristics analysis was performed for response and survival data. CIs for the performance indices were obtained with a nonparametric bootstrap procedure. Findings were externally validated on a series of 67 samples treated in a similar setting.

    Results: In KRAS wild type (WT) patients, there was a significant association between log-transformed ligand expression and response for EREG (odds ratio for objective response, 1.90; 95% CI, 1.27 to 2.83; P = .0005; concordance index [c-index], 0.681) and for AREG (odds ratio for objective response, 1.862; 95% CI, 1.22 to 2.72; P = .0017; c-index, 0.673). In a Cox regression model, dichotomized ligand expression was significantly associated with progression-free survival (PFS) and overall survival (OS). EREG PFS hazard ratio (HR) was 0.41 (95% CI, 0.274 to 0.609; P < .001; time-dependent c-index [Ctau index], 0.640), and AREG PFS HR was 0.43 (95% CI, 0.29 to 0.64; P < .001; Ctau index, 0.627). EREG OS HR was 0.42 (95% CI, 0.28 to 0.63; P < .0001; Ctau index, 0.639), and AREG OS HR was 0.40 (95% CI, 0.27 to 0.64; P < .0001; Ctau index, 0.625). There was no predictive power of ligand expression in patients with KRAS mutation.

    Conclusion: Expression of EGFR ligands in primary tumors significantly predicts outcome in KRAS WT cmCRC treated with cetuximab and irinotecan.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2009;27;30;5068-74

  • RAS and CSF3R mutations in severe congenital neutropenia.

    Germeshausen M, Kratz CP, Ballmaier M and Welte K

    Funded by: NIAID NIH HHS: R24 AI049393

    Blood 2009;114;16;3504-5

  • RAS mutations affect tumor necrosis factor-induced apoptosis in colon carcinoma cells via ERK-modulatory negative and positive feedback circuits along with non-ERK pathway effects.

    Kreeger PK, Mandhana R, Alford SK, Haigis KM and Lauffenburger DA

    Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts02139, USA.

    More than 40% of colon cancers have a mutation in K-RAS or N-RAS, GTPases that operate as central hubs for multiple key signaling pathways within the cell. Utilizing an isogenic panel of colon carcinoma cells with K-RAS or N-RAS variations, we observed differences in tumor necrosis factor-alpha (TNFalpha)-induced apoptosis. When the dynamics of phosphorylated ERK response to TNFalpha were examined, K-RAS mutant cells showed lower activation whereas N-RAS mutant cells exhibited prolonged duration. These divergent trends were partially explained by differential induction of two ERK-modulatory circuits: negative feedback mediated by dual-specificity phosphatase 5 and positive feedback by autocrine transforming growth factor-alpha. Moreover, in the various RAS mutant colon carcinoma lines, the transforming growth factor-alpha autocrine loop differentially elicited a further downstream chemokine (CXCL1/CXCL8) autocrine loop, with the two loops having opposite effects on apoptosis. Although the apoptotic responses of the RAS mutant panel to TNFalpha treatment showed significant dependence on the respective phosphorylated ERK dynamics, successful prediction across the various cell lines required contextual information concerning additional pathways including IKK and p38. A quantitative computational model based on weighted linear combinations of these pathway activities successfully predicted not only the spectrum of cell death responses but also the corresponding chemokine production responses. Our findings indicate that diverse RAS mutations yield differential cell behavioral responses to inflammatory cytokine exposure by means of (a) differential effects on ERK activity via multiple feedback circuit mechanisms, and (b) differential effects on other key signaling pathways contextually modulating ERK-related dependence.

    Funded by: NCI NIH HHS: U54 CA112967, U54 CA112967-05, U54-CA112967; NIGMS NIH HHS: P50 GM068762, P50-GM68762

    Cancer research 2009;69;20;8191-9

  • Analysis of mutations in TP53, APC, K-ras, and DCC genes in the non-dysplastic mucosa of patients with inflammatory bowel disease.

    Rapozo DC, Grinmann AB, Carvalho AT, de Souza HS, Soares-Lima SC, de Almeida Simão T, de Paiva D, Abby F, Albano RM and Pinto LF

    Departamento de Bioquímica, Instituto de Biologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil, 20551030.

    Patients with ulcerative colitis (UC) and Crohn's disease (CD) have a high risk for colorectal cancer (CRC). To understand the molecular basis of colitis-associated CRC, we analyzed alterations in TP53, APC, K-ras, and DCC genes in the non-dysplastic UC and CD colon.

    Endoscopic biopsies were collected from six predefined colon sites of 35 UC and 12 CD patients for DNA extraction and genetic analysis.

    Results: A mutation was found in codon 1141 of the APC gene of two CD patients, being somatic in one and germinative in the other. The mutation seen in both patients was a base exchange of thymine for cytosine, resulting in an exchange of leucine for serine. We did not detect any mutations in the other samples analyzed.

    Conclusions: Mutations in APC gene may occur in the non-dysplastic CD mucosa of patients with disease for more than 10 years. The follow-up of these patients will show the likelihood of mutant APC progressing to CRC in CD. Further analysis will be required for evaluating the impact of these findings in the context of cancer surveillance in inflammatory bowel disease.

    International journal of colorectal disease 2009;24;10;1141-8

  • Cetuximab plus cisplatin-5-fluorouracil versus cisplatin-5-fluorouracil alone in first-line metastatic squamous cell carcinoma of the esophagus: a randomized phase II study of the Arbeitsgemeinschaft Internistische Onkologie.

    Lorenzen S, Schuster T, Porschen R, Al-Batran SE, Hofheinz R, Thuss-Patience P, Moehler M, Grabowski P, Arnold D, Greten T, Müller L, Röthling N, Peschel C, Langer R and Lordick F

    Third Department of Internal Medicine (Hematology/Medical Oncology), Technical University of Munich, Munich. florian.lordick@med.uni-heidelberg.de

    Background: This study assessed the activity of the mAb cetuximab in combination with cisplatin and 5-fluorouracil (5-FU) in advanced esophageal squamous cell carcinoma.

    For a maximum of six 29-day cycles, patients received cisplatin 100 mg/m(2), day 1, plus 5-FU 1000 mg/m(2), days 1-5 (CF), either alone or in combination with cetuximab (CET-CF; 400 mg/m(2) initial dose followed by 250 mg/m(2) weekly thereafter). The primary end point was tumor response. Tumor material was obtained for analysis of KRAS mutation status.

    Results: Sixty-two eligible patients were included, 32 receiving CET-CF and 30 CF. Cetuximab did not exacerbate grade 3/4 toxicity, except for rash (6% versus 0%) and diarrhea (16% versus 0%). The overall response rate according to RECIST criteria was 19% and 13% and the disease control rate 75% and 57% for the CET-CF and CF arms, respectively. With a median follow-up of 21.5 months, the median progression-free survival was 5.9 and 3.6 months and median overall survival 9.5 and 5.5 months for CET-CF and CF, respectively. No KRAS codon 12/13 tumor mutations were identified in 37 evaluated samples.

    Conclusion: Cetuximab can be safely combined with CF chemotherapy and may increase the efficacy of standard CF chemotherapy.

    Annals of oncology : official journal of the European Society for Medical Oncology / ESMO 2009;20;10;1667-73

  • Epidermal growth factor receptor and K-RAS mutations in 411 lung adenocarcinoma: a population-based prospective study.

    Boldrini L, Alì G, Gisfredi S, Ursino S, Baldini E, Melfi F, Lucchi M, Comin CE, Maddau C, Tibaldi C, Camacci T, Servadio A, Mussi A and Fontanini G

    Department of Surgery, University of Pisa, Pisa, Italy.

    Targeting the epidermal growth factor receptor has played a central role in advanced non-small cell lung cancer research, treatment, and patient outcomes over the last several years; however, a number of questions about this approach remain to be addressed. Through the Istituto Toscano Tumori and the Italian Association of Women Against Lung Cancer Project, we collected 411 lung adenocarcinomas from several clinical centers in Tuscany. Mutations were assessed by sequencing exons 18-21 of the epidermal growth factor receptor gene, and by restriction fragment length polymorphism analysis of codons 12 and 13 of the K-RAS gene. Epidermal growth factor receptor mutations (12.6%) were more frequently observed in females (p<0.0001), in non-smokers (p=0.005), and in the presence of bronchioloalveolar features (p=0.0004). K-RAS mutations (17.9%) were more frequent in males (p=0.0007) and were associated with smoking habits (p=0.005). Epidermal growth factor receptor and K-RAS mutations were mutually exclusive (p=0.001). We focused on 21 female patients with advanced/metastatic lung adenocarcinoma who received gefitinib 250 mg/day (expanded access) or erlotinib 150 mg/die as second/third-line therapy; partial response was associated with classic epidermal growth factor receptor mutations (p=0.006) and with a non-smoking history (p=0.02). None of the female patients with partial response and/or stable disease showed K-RAS alterations. Although the data obtained in our study have yet to be analyzed and confirmed with a larger number of patients treated with tyrosine kinase inhibitors, they should provide useful information for targeted therapy, in particular for non-smoking female lung cancer patients.

    Oncology reports 2009;22;4;683-91

  • In situ evidence of KRAS amplification and association with increased p21 levels in non-small cell lung carcinoma.

    Wagner PL, Perner S, Rickman DS, LaFargue CJ, Kitabayashi N, Johnstone SF, Weir BA, Meyerson M, Altorki NK and Rubin MA

    Departments of Pathology, Laboratory MedicineCardiothoracic Surgery, Weill Medical College of Cornell University, New York, NY, USA.

    Recent advances in the characterization of the lung cancer genome have suggested that KRAS may frequently be amplified, although little is known regarding the significance of this finding. This is in contrast with activating mutations of KRAS, which occur in approximately 20% of non-small cell lung carcinomas (NSCLCs). We used fluorescence in situ hybridization to provide direct evidence of KRAS amplification for the first time in clinical specimens. We detected amplification in 7 of 100 consecutive NSCLCs, with a concurrent activating KRAS mutation in 4 cases. KRAS amplification was associated with greater expression of p21 as assessed by quantitative immunohistochemical analysis (P = .015). Our data indicate that a sizable subgroup of NSCLCs harbor KRAS amplification, some of which also contain point mutations, and suggest that an increased KRAS copy number may drive p21 overexpression. KRAS amplification may define a unique clinicopathologic subset of NSCLCs with potentially altered responsiveness to targeted therapies.

    American journal of clinical pathology 2009;132;4;500-5

  • Resequencing analysis of the human tyrosine kinase gene family in pancreatic cancer.

    Kubo T, Kuroda Y, Kokubu A, Hosoda F, Arai Y, Hiraoka N, Hirohashi S and Shibata T

    National Cancer Center Research Institute, Chuo-ku, Tokyo, Japan.

    Objectives: Pancreatic cancer is one of the most intractable of cancers. However, the comprehensive view of somatic mutations in this tumor is far from clear. The tyrosine kinase (TK) gene family, which encodes important regulators of various signal transduction pathways, is one of the most frequently altered gene families in human cancer.

    Methods: To clarify the somatic mutation profile of TKs in pancreatic cancer, we performed a systematic screening of mutations in the kinase domains of all human TK genes (636 exons of 90 genes in total) in 11 pancreatic cancer cell lines and 29 microdissected primary tumors.

    Results: We identified 15 nonsynonymous alterations that included 9 DNA alterations in cell lines and 6 somatic mutations in primary tumors. In particular, we identified the previously reported pathogenic mutation of NTRK3 in a KRAS/BRAF wild-type tumor and 2 somatic mutations in the Src family of kinases (YES1 and LYN) that would be expected to cause structural changes.

    Conclusions: Our genome-wide resequencing approach revealed novel oncogenic pathways in pancreatic cancers.

    Pancreas 2009;38;7;e200-6

  • Prognostic significance and molecular associations of 18q loss of heterozygosity: a cohort study of microsatellite stable colorectal cancers.

    Ogino S, Nosho K, Irahara N, Shima K, Baba Y, Kirkner GJ, Meyerhardt JA and Fuchs CS

    Center for Molecular Oncologic Pathology, Dana-Farber Cancer Institute, Brigham and Women's Hospital, Harvard Medical School, 44 Binney St, Room JF-215C, Boston, MA 02115 USA. shuji_ogino@dfci.harvard.edu

    Purpose: Loss of heterozygosity (LOH) at chromosome 18q frequently occurs late during colon cancer development and is inversely associated with microsatellite instability (MSI). 18q LOH has been reported to predict shorter survival in patients with colorectal cancer, whereas MSI-high status has been associated with superior prognosis. However, it is unclear whether 18q LOH in colorectal cancer has any prognostic implication independent of MSI status and other potential predictors of clinical outcome.

    Among 555 non-MSI-high colorectal cancers (stage I to IV) in two independent prospective cohort studies, we examined 18q LOH in relation to other molecular events and patient survival. Cox proportional hazard models computed hazard ratio of death, adjusted for clinical and tumoral characteristics, including KRAS, BRAF, PIK3CA, beta-catenin, p53, CpG island methylator phenotype, LINE-1 methylation, and John Cunningham (JC) virus T antigen.

    Results: In multivariate logistic regression, 18q LOH was independently associated with JC virus T antigen (odds ratio [OR] = 1.93; P = .0077), body mass index > or = 30 kg/m(2) (obesity; OR = 2.01; P = .014), high tumor grade (OR = 0.40; P = .018), KRAS mutation (OR = 0.66; P = .40), and LINE-1 hypomethylation (for a 30% decrease; OR = 1.92; P = .045). Five-year colorectal cancer-specific survival was 75% among patients with 18q LOH-positive tumors and 74% among those with 18q LOH-negative tumors (log-rank P = .80). Five-year overall survival was 70% among patients with 18q LOH-positive tumors and 68% among those with 18q LOH-negative tumors (log-rank P = .54). Multivariate analysis did not show prognostic significance of 18q LOH.

    Conclusion: In our large prospective study of patients with non-MSI-high colorectal cancer, 18q LOH or allelic imbalance was not associated with patient survival.

    Funded by: NCI NIH HHS: K07 CA097992, K07 CA122826, K07 CA97992, P01 CA055075, P01 CA087969, P01 CA55075, P01 CA87969, P50 CA127003

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2009;27;27;4591-8

  • Glucose deprivation contributes to the development of KRAS pathway mutations in tumor cells.

    Yun J, Rago C, Cheong I, Pagliarini R, Angenendt P, Rajagopalan H, Schmidt K, Willson JK, Markowitz S, Zhou S, Diaz LA, Velculescu VE, Lengauer C, Kinzler KW, Vogelstein B and Papadopoulos N

    Ludwig Center for Cancer Genetics and Therapeutics and Howard Hughes Medical Institute, Johns Hopkins Kimmel Cancer Center, Baltimore, MD 21231, USA.

    Tumor progression is driven by genetic mutations, but little is known about the environmental conditions that select for these mutations. Studying the transcriptomes of paired colorectal cancer cell lines that differed only in the mutational status of their KRAS or BRAF genes, we found that GLUT1, encoding glucose transporter-1, was one of three genes consistently up-regulated in cells with KRAS or BRAF mutations. The mutant cells exhibited enhanced glucose uptake and glycolysis and survived in low-glucose conditions, phenotypes that all required GLUT1 expression. In contrast, when cells with wild-type KRAS alleles were subjected to a low-glucose environment, very few cells survived. Most surviving cells expressed high levels of GLUT1, and 4% of these survivors had acquired KRAS mutations not present in their parents. The glycolysis inhibitor 3-bromopyruvate preferentially suppressed the growth of cells with KRAS or BRAF mutations. Together, these data suggest that glucose deprivation can drive the acquisition of KRAS pathway mutations in human tumors.

    Funded by: NCI NIH HHS: CA43460, CA62924, R37 CA043460, R37 CA043460-27

    Science (New York, N.Y.) 2009;325;5947;1555-9

  • Ethnic differences and functional analysis of MET mutations in lung cancer.

    Krishnaswamy S, Kanteti R, Duke-Cohan JS, Loganathan S, Liu W, Ma PC, Sattler M, Singleton PA, Ramnath N, Innocenti F, Nicolae DL, Ouyang Z, Liang J, Minna J, Kozloff MF, Ferguson MK, Natarajan V, Wang YC, Garcia JG, Vokes EE and Salgia R

    Department of Medicine, The University of Chicago, Chicago, Illinois, USA.

    Purpose: African Americans have higher incidence and poorer response to lung cancer treatment compared with Caucasians. However, the underlying molecular mechanisms for the significant ethnic difference are not known. The present study examines the ethnic differences in the type and frequency of MET proto-oncogene (MET) mutation in lung cancer and correlated them with other frequently mutated genes such as epidermal growth factor receptor (EGFR), KRAS2, and TP53.

    Using tumor tissue genomic DNA from 141 Asian, 76 Caucasian, and 66 African American lung cancer patients, exons coding for MET and EGFR were PCR amplified, and mutations were detected by sequencing. Mutation carriers were further screened for KRAS2 and TP53 mutations. Functional implications of important MET mutations were explored by molecular modeling and hepatocyte growth factor binding studies.

    Results: Unlike the frequently encountered somatic mutations in EGFR, MET mutations in lung tumors were germline. MET-N375S, the most frequent mutation of MET, occurred in 13% of East Asians compared with none in African Americans. The frequency of MET mutations was highest among male smokers and squamous cell carcinoma. The MET-N375S mutation seems to confer resistance to MET inhibition based on hepatocyte growth factor ligand binding, molecular modeling, and apoptotic susceptibility to MET inhibitor studies.

    Conclusions: MET in lung cancer tissues contained nonsynonymous mutations in the semaphorin and juxtamembrane domains but not in the tyrosine kinase domain. All the MET mutations were germline. East Asians, African-Americans, and Caucasians had different MET genotypes and haplotypes. MET mutations in the semaphorin domain affected ligand binding.

    Funded by: NCI NIH HHS: P50 CA070907-10, P50 CA070907-11, P50 CA070907-12, P50CA70907, R01 CA-125541-01, R01 CA100750-04, R01 CA100750-06, R01 CA125541-03, R01 CA129501-01A1, R01 CA129501-02; NHLBI NIH HHS: P01 HL058064-140009, P01HL058064-13; NIGMS NIH HHS: R01 GM079804-05

    Clinical cancer research : an official journal of the American Association for Cancer Research 2009;15;18;5714-23

  • Molecular markers of response and toxicity to FOLFOX chemotherapy in metastatic colorectal cancer.

    Chua W, Goldstein D, Lee CK, Dhillon H, Michael M, Mitchell P, Clarke SJ and Iacopetta B

    Department of Medical Oncology, Sydney Cancer Centre, Concord Repatriation General Hospital, Sydney, NSW, Australia. weic@med.usyd.edu.au

    Background: To investigate three genetic alterations (TP53 mutation, Kras mutation and microsatellite instability (MSI)) and three polymorphisms (methylene tetrahydrofolate reductase (MTHFR) C677T, excision repair cross complementing group 1 (ERCC1)-118 and X-ray repair cross complementing group 1 (XRCC1)-399) for their ability to predict response, survival and toxicity to FOLFOX first line chemotherapy in the treatment of metastatic colorectal cancer (mCRC).

    Methods: Tumour tissues from 118 mCRC patients who underwent FOLFOX treatment from three successive phase II trials were evaluated for mutations in TP53 (exons 5-8) and Kras (codons 12 and 13) and for MSI using PCR-based analysis. Genotyping for common single nucleotide polymorphisms in the MTHFR (codon 677), ERCC1 (codon 118) and XRCC1 (codon 399) genes was also carried out using PCR techniques. These genetic markers were correlated with clinical response, survival and toxicity to treatment.

    Results: Patients with the T allele of ERCC1-118 showed significantly worse progression-free survival in univariate analysis (HR=2.62; 95% CI=1.14-6.02; P=0.02). None of the genetic alterations or polymorphisms showed significant association with clinical response to FOLFOX. The MTHFR, ERCC1 and XRCC1 polymorphisms showed no associations with overall haematological, gastrointestinal or neurological toxicity to FOLFOX, although MTHFR 677 TT genotype patients showed a significantly higher incidence of grade 3 or 4 diarrhoea (26%) compared with CC or CT genotype patients (6%, P=0.02).

    Conclusions: The ERCC1-118 and MTHFR C677T polymorphisms were associated with progression and severe diarrhoea, respectively, after FOLFOX treatment in mCRC. Although our findings require confirmation in large prospective studies, they reinforce the concept that individual genetic variation may allow personalized selection of chemotherapy to optimize clinical outcomes.

    British journal of cancer 2009;101;6;998-1004

  • Clinical features and outcome of patients with non-small-cell lung cancer who harbor EML4-ALK.

    Shaw AT, Yeap BY, Mino-Kenudson M, Digumarthy SR, Costa DB, Heist RS, Solomon B, Stubbs H, Admane S, McDermott U, Settleman J, Kobayashi S, Mark EJ, Rodig SJ, Chirieac LR, Kwak EL, Lynch TJ and Iafrate AJ

    Department of Pathology, Massachusetts General Hospital, Warren 501c, 55 Fruit St, Boston, MA 02114, USA.

    Purpose: The EML4-ALK fusion oncogene represents a novel molecular target in a small subset of non-small-cell lung cancers (NSCLC). To aid in identification and treatment of these patients, we examined the clinical characteristics and treatment outcomes of patients who had NSCLC with and without EML4-ALK.

    Patients with NSCLC were selected for genetic screening on the basis of two or more of the following characteristics: female sex, Asian ethnicity, never/light smoking history, and adenocarcinoma histology. EML4-ALK was identified by using fluorescent in situ hybridization for ALK rearrangements and was confirmed by immunohistochemistry for ALK expression. EGFR and KRAS mutations were determined by DNA sequencing.

    Results: Of 141 tumors screened, 19 (13%) were EML4-ALK mutant, 31 (22%) were EGFR mutant, and 91 (65%) were wild type (WT/WT) for both ALK and EGFR. Compared with the EGFR mutant and WT/WT cohorts, patients with EML4-ALK mutant tumors were significantly younger (P < .001 and P = .005) and were more likely to be men (P = .036 and P = .039). Patients with EML4-ALK-positive tumors, like patients who harbored EGFR mutations, also were more likely to be never/light smokers compared with patients in the WT/WT cohort (P < .001). Eighteen of the 19 EML4-ALK tumors were adenocarcinomas, predominantly the signet ring cell subtype. Among patients with metastatic disease, EML4-ALK positivity was associated with resistance to EGFR tyrosine kinase inhibitors (TKIs). Patients in the EML4-ALK cohort and the WT/WT cohort showed similar response rates to platinum-based combination chemotherapy and no difference in overall survival.

    Conclusion: EML4-ALK defines a molecular subset of NSCLC with distinct clinical characteristics. Patients who harbor this mutation do not benefit from EGFR TKIs and should be directed to trials of ALK-targeted agents.

    Funded by: NCI NIH HHS: CA090578, P20 CA090578, P50 CA090578

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2009;27;26;4247-53

  • Concomitant mutations and splice variants in KRAS and BRAF demonstrate complex perturbation of the Ras/Raf signalling pathway in advanced colorectal cancer.

    Seth R, Crook S, Ibrahem S, Fadhil W, Jackson D and Ilyas M

    Division of Pathology, School of Molecular Medical Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, UK.

    KRAS and BRAF mutations occur in colorectal cancers (CRCs) and are considered mutually exclusive methods of activating the RAS/RAF/MEK/ERK pathway. This pathway is a therapeutic target and KRAS mutation may predict tumour responsiveness. The purpose of this study was to investigate the relationship between KRAS and BRAF mutations in 24 CRC cell lines and 29 advanced CRCs.

    Methods: KRAS and BRAF mutations were detected using high resolution melting and sequencing. Expression of mutations was confirmed by reverse transcription- PCR (RT-PCR) and sequencing. CpG island methylator phenotype (CIMP) was tested by methylation-specific PCR.

    Results: KRAS or BRAF mutation occurred in 79% of cell lines and 59% of CRCs. In the cell lines, KRAS mutations occurred in 54% of cases (with 62% in codons 12/13 and 38% in other codons). Four cell lines had a homozygous mutation. Only heterozygous BRAF mutations were detected in 29% cell lines. The V600E mutation occurred most commonly and was associated with CIMP+ status (p = 0.005). Mutations at codons 529 and 581 were also found and, in one case, BRAF and KRAS mutation co-occurred. Unexpectedly, BRAF splice variants (with a predicted kinase-dead protein) were found in 5/24 (21%) cell lines. In advanced CRCs, KRAS mutations occurred in 48% of cases (64% codons 12/13, 36% other codons) and BRAF mutations in 10% (66% V600E, 33% exon 11). A compound KRAS/BRAF mutation was not seen.

    Conclusions: Disrupted Ras/Raf signalling is common in CRC. Homozygous KRAS mutations and concomitant KRAS/BRAF mutations may be indicative of a gene dosage effect. The significance of BRAF splice variants is uncertain but may represent another layer of complexity. Finally, if KRAS mutation is to be used for predictive testing, then the whole gene may need to be screened as mutations occur outside codons 12/13.

    Gut 2009;58;9;1234-41

  • Mutation detection of KRAS by high-resolution melting analysis in Chinese with gastric cancer.

    Liu ZM, Liu LN, Li M, Zhang QP, Cheng SH and Lu S

    Laboratory Center, The Second Affiliated Hospital of Dalian Medical University, Dalian 116027, PR China.

    KRAS proteins play an important role in regulating cell functions. A series of studies has revealed that mutations of KRAS are involved in gastric carcinogenesis. However, mutation status of KRAS remains unclear in gastric cancer from Chinese Mainland. It has been proved that KRAS mutation associates with resistance to epidermal growth factor receptor (EGFR) inhibitors. In this study, KRAS mutations were detected in 52 gastric adenocarcinomas from Northern China. High-resolution melting analysis (HRMA) was used and positive samples were confirmed by direct sequencing. Of the 52 cancers, KRAS mutations were found in 5 (9.6%). All cancers with KRAS mutation were from male patients. Frequencies of KRAS mutation were 14.3% (3/21) and 6.5% (2/31) in differentiated and undifferentiated cancers; 25% (1/4) and 8.3% (4/48) in early and advanced wall penetration cancers; and were 13.3% (2/15) and 8.1% (3/37) in without and with lymph node metastasis cancers, respectively. There was no significant correlation between KRAS mutation and clinicopathological features. There were 3 mutation types in the 5 mutations, including 2 G12D, 1 G12V and 2 G13D mutations. All codon 12 mutations were found in patients with lymph node metastasis and at advanced stage, whereas all codon 13 mutations were found in patients without lymph node metastasis and at early stage. These results support KRAS mutation may only be involved in carcinogenesis of partial gastric cancers and the different mutation types of KRAS may take part in development of gastric cancer at different stages. The resistance of partial gastric cancer patients to EGFR inhibitors may be induced by KRAS mutation.

    Oncology reports 2009;22;3;515-20

  • Prognostic value of KRAS mutations and Ki-67 expression in stage I lung adenocarcinomas.

    Woo T, Okudela K, Yazawa T, Wada N, Ogawa N, Ishiwa N, Tajiri M, Rino Y, Kitamura H and Masuda M

    Division of Thoracic Surgery, Kanagawa Prefectural Cardiovascular and Respiratory Center Hospital, Yokohama, Japan. tetsu.n.u@cotton.ocn.ne.jp

    The purpose of the present study was to establish accurate prognostic markers to predict the post-operative recurrence of stage I lung adenocarcinomas (ADC). One-hundred and ninety cases of stage I ADC were examined for KRAS mutations and Ki-67 expression, and their associations with disease recurrence were analyzed. KRAS-mutated cases showed a significantly higher risk of recurrence than cases without mutations (5-year disease-free survival (DFS) 61.0% vs. 85.8%, P=0.017: adjusted Hazard ratio (HR) 4.55, 95% Confidence Interval (CI) 1.61-12.82, P=0.004). Ki-67 high-expressers (labeling index >10%) also showed a higher risk of recurrence than low-expressers (5-year DFS 68.7% vs. 93.2%, P<0.001: adjusted HR 3.84, 95% CI 1.18-12.45, P=0.025). Ki-67 high-expressers with KRAS mutations showed an additional higher risk of recurrence compared to low-expressers without mutations (5-year DFS 37.5% vs. 93.3%, P<0.001: adjusted HR 16.82, 95% CI 3.77-74.98, P<0.001) and their 5-year DFS was nearly equivalent to that of stage II non-small cell lung cancer (NSCLC) in our facility (37.5% vs. 37.2% for stage II NSCLC, p=0.577). The combined use of KRAS status and Ki-67 expression level could be an excellent prognostic marker to predict the post-operative recurrence of stage I ADC.

    Lung cancer (Amsterdam, Netherlands) 2009;65;3;355-62

  • Luteolin, quercetin and ursolic acid are potent inhibitors of proliferation and inducers of apoptosis in both KRAS and BRAF mutated human colorectal cancer cells.

    Xavier CP, Lima CF, Preto A, Seruca R, Fernandes-Ferreira M and Pereira-Wilson C

    Centre of Molecular and Environmental Biology/Department of Biology, University of Minho, Braga, Portugal.

    KRAS and BRAF mutations are frequent in colorectal carcinoma (CRC) and have the potential to activate proliferation and survival through MAPK/ERK and/or PI3K signalling pathways. Because diet is one of the most important determinants of CRC incidence and progression, we studied the effects of the dietary phytochemicals quercetin (Q), luteolin (L) and ursolic acid (UA) on cell proliferation and apoptosis in two human CRC derived cell lines, HCT15 and CO115, harboring KRAS and BRAF activating mutations, respectively. In KRAS mutated HCT15 cells, Q and L significantly decreased ERK phosphorylation, whereas in BRAF mutated CO115 cells the three compounds decreased Akt phosphorylation but had no effect on phospho-ERK. Our findings show that these natural compounds have antiproliferative and proapoptotic effects and simultaneously seem to act on KRAS and PI3K but not on BRAF. These results shed light on the molecular mechanisms of action of Q, L and UA and emphasize the potential of dietary choices for the control of CRC progression.

    Cancer letters 2009;281;2;162-70

  • The hypervariable region of K-Ras4B is responsible for its specific interactions with calmodulin.

    Abraham SJ, Nolet RP, Calvert RJ, Anderson LM and Gaponenko V

    Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois 60607, USA.

    K-Ras4B belongs to the family of p21 Ras GTPases, which play an important role in cell proliferation, survival, and motility. The p21 Ras proteins, such as K-Ras4B, K-Ras4A, H-Ras, and N-Ras, share 85% sequence homology and activate very similar signaling pathways. Only the C-terminal hypervariable regions differ significantly. A growing body of literature demonstrates that each Ras isoform possesses unique functions in normal physiological processes as well as in pathogenesis. One of the central questions in the field of Ras biology is how these very similar proteins achieve such remarkable specificity in protein-protein interactions that regulate signal transduction pathways. Here we explore specific binding of K-Ras4B to calmodulin. Using NMR techniques and isothermal titration calorimetry, we demonstrate that the hypervariable region of K-Ras4B contributes in a major way to the interaction with calmodulin, while the catalytic domain of K-Ras4B provides a way to control the interaction by nucleotide binding. The hypervariable region of K-Ras4B binds specifically to the C-terminal domain of Ca(2+)-loaded calmodulin with micromolar affinity, while the GTP-gamma-S-loaded catalytic domain of K-Ras4B may interact with the N-terminal domain of calmodulin.

    Funded by: NCI NIH HHS: Z01 BC005399-24

    Biochemistry 2009;48;32;7575-83

  • KRAS codon 61, 146 and BRAF mutations predict resistance to cetuximab plus irinotecan in KRAS codon 12 and 13 wild-type metastatic colorectal cancer.

    Loupakis F, Ruzzo A, Cremolini C, Vincenzi B, Salvatore L, Santini D, Masi G, Stasi I, Canestrari E, Rulli E, Floriani I, Bencardino K, Galluccio N, Catalano V, Tonini G, Magnani M, Fontanini G, Basolo F, Falcone A and Graziano F

    Unit of Medical Oncology 2, Azienda-Ospedaliero Universitaria Pisana, Istituto Toscano Tumori and Department of Oncology, Transplantes and New Technologies in Medicine, University of Pisa, Via Roma 67 - 56126 Pisa, Italy.

    Background: KRAS codons 12 and 13 mutations predict resistance to anti-EGFR monoclonal antibodies (moAbs) in metastatic colorectal cancer. Also, BRAF V600E mutation has been associated with resistance. Additional KRAS mutations are described in CRC.

    Methods: We investigated the role of KRAS codons 61 and 146 and BRAF V600E mutations in predicting resistance to cetuximab plus irinotecan in a cohort of KRAS codons 12 and 13 wild-type patients.

    Results: Among 87 KRAS codons 12 and 13 wild-type patients, KRAS codons 61 and 146 were mutated in 7 and 1 case, respectively. None of mutated patients responded vs 22 of 68 wild type (P=0.096). Eleven patients were not evaluable. KRAS mutations were associated with shorter progression-free survival (PFS, HR: 0.46, P=0.028). None of 13 BRAF-mutated patients responded vs 24 of 74 BRAF wild type (P=0.016). BRAF mutation was associated with a trend towards shorter PFS (HR: 0.59, P=0.073). In the subgroup of BRAF wild-type patients, KRAS codons 61/146 mutations determined a lower response rate (0 vs 37%, P=0.047) and worse PFS (HR: 0.45, P=0.023). Patients bearing KRAS or BRAF mutations had poorer response rate (0 vs 37%, P=0.0005) and PFS (HR: 0.51, P=0.006) compared with KRAS and BRAF wild-type patients.

    Conclusion: Assessing KRAS codons 61/146 and BRAF V600E mutations might help optimising the selection of the candidate patients to receive anti-EGFR moAbs.

    British journal of cancer 2009;101;4;715-21

  • Impact of epidermal growth factor receptor and KRAS mutations on clinical outcomes in previously untreated non-small cell lung cancer patients: results of an online tumor registry of clinical trials.

    Jackman DM, Miller VA, Cioffredi LA, Yeap BY, Jänne PA, Riely GJ, Ruiz MG, Giaccone G, Sequist LV and Johnson BE

    Lowe Center for Thoracic Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA. djackman@partners.org

    Purpose: The impact of epidermal growth factor receptor (EGFR) and KRAS genotypes on outcomes with erlotinib or gefitinib therapy continues to be debated. This study combines patient data from five trials in predominantly Western populations to assess the impact of EGFR and KRAS mutations on first-line therapy with an EGFR-tyrosine kinase inhibitor (TKI) and compare clinical versus molecular predictors of sensitivity.

    Chemotherapy-naïve patients with advanced non-small cell lung cancer and known EGFR mutation status treated with erlotinib or gefitinib monotherapy as part of a clinical trial were eligible for inclusion. Patients received daily erlotinib (150 mg) or gefitinib (250 mg) until disease progression or unacceptable toxicity. Data were collected in a password-protected web database. Clinical outcomes were analyzed to look for differences based on EGFR and KRAS genotypes, as well as clinical characteristics.

    Results: Patients (223) from five clinical trials were included. Sensitizing EGFR mutations were associated with a 67% response rate, time to progression (TTP) of 11.8 months, and overall survival of 23.9 months. Exon 19 deletions were associated with longer median TTP and overall survival compared with L858R mutations. Wild-type EGFR was associated with poorer outcomes (response rate, 3%; TTP, 3.2 months) irrespective of KRAS status. No difference in outcome was seen between patients harboring KRAS transition versus transversion mutations. EGFR genotype was more effective than clinical characteristics at selecting appropriate patients for consideration of first-line therapy with an EGFR-TKI.

    Conclusion: EGFR mutation status is associated with sensitivity to treatment with an EGFR-TKI in patients with advanced non-small cell lung cancer. Patients harboring sensitizing EGFR mutations should be considered for first-line erlotinib or gefitinib.

    Funded by: NCI NIH HHS: 5R01 CA 114465-05, R01 CA114465-05

    Clinical cancer research : an official journal of the American Association for Cancer Research 2009;15;16;5267-73

  • Presence of activating KRAS mutations correlates significantly with expression of tumour suppressor genes DCN and TPM1 in colorectal cancer.

    Mlakar V, Berginc G, Volavsek M, Stor Z, Rems M and Glavac D

    Department of Molecular Genetics, Institute of Pathology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia. vid.mlakar@mf.uni-lj.si

    Background: Despite identification of the major genes and pathways involved in the development of colorectal cancer (CRC), it has become obvious that several steps in these pathways might be bypassed by other as yet unknown genetic events that lead towards CRC. Therefore we wanted to improve our understanding of the genetic mechanisms of CRC development.

    Methods: We used microarrays to identify novel genes involved in the development of CRC. Real time PCR was used for mRNA expression as well as to search for chromosomal abnormalities within candidate genes. The correlation between the expression obtained by real time PCR and the presence of the KRAS mutation was investigated.

    Results: We detected significant previously undescribed underexpression in CRC for genes SLC26A3, TPM1 and DCN, with a suggested tumour suppressor role. We also describe the correlation between TPM1 and DCN expression and the presence of KRAS mutations in CRC. When searching for chromosomal abnormalities, we found deletion of the TPM1 gene in one case of CRC, but no deletions of DCN and SLC26A3 were found.

    Conclusion: Our study provides further evidence of decreased mRNA expression of three important tumour suppressor genes in cases of CRC, thus implicating them in the development of this type of cancer. Moreover, we found underexpression of the TPM1 gene in a case of CRCs without KRAS mutations, showing that TPM1 might serve as an alternative path of development of CRC. This downregulation could in some cases be mediated by deletion of the TPM1 gene. On the other hand, the correlation of DCN underexpression with the presence of KRAS mutations suggests that DCN expression is affected by the presence of activating KRAS mutations, lowering the amount of the important tumour suppressor protein decorin.

    BMC cancer 2009;9;282

  • Prognostic and predictive value of common mutations for treatment response and survival in patients with metastatic colorectal cancer.

    Souglakos J, Philips J, Wang R, Marwah S, Silver M, Tzardi M, Silver J, Ogino S, Hooshmand S, Kwak E, Freed E, Meyerhardt JA, Saridaki Z, Georgoulias V, Finkelstein D, Fuchs CS, Kulke MH and Shivdasani RA

    Department of Medical Oncology, University Hospital of Heraklion, Voutes and Stavrakia, Heraklion, Crete, Greece. georgsec@med.uoc.gr

    Background: We address the prognostic and predictive value of KRAS, PIK3CA and BRAF mutations for clinical outcomes in response to active agents in the treatment of metastatic colorectal cancer (mCRC).

    Methods: We determined KRAS, BRAF and PIK3CA mutations in tumours from 168 patients treated for mCRC at two institutions. All patients received 5-FU-based first-line chemotherapy and treatment outcome was analysed retrospectively.

    Results: KRAS, BRAF and PIK3CA mutations were present in 62 (37%), 13 (8%) and 26 (15%) cases, respectively. Multivariate analysis uncovered BRAF mutation as an independent prognostic factor for decreased survival (hazard ratio (HR) 4.0, 95% confidence interval (CI) 2.1-7.6). In addition, patients with BRAF-mutant tumours had significantly lower progression-free survival (PFS: HR 4.0, 95% CI 2.2-7.4) than those whose tumors that carried wild-type BRAF. Among 92 patients treated using chemotherapy and cetuximab as salvage therapy, KRAS mutation was associated with lack of response (P=0.002) and shorter PFS (P=0.09). BRAF (P=0.0005) and PIK3CA (P=0.01) mutations also predicted reduced PFS in response to cetuximab salvage therapy.

    Conclusions: These results underscore the potential of mutational profiling to identify CRCs with different natural histories or treatment responses. The adverse significance of BRAF mutation should inform patient selection and stratification in clinical trials.

    Funded by: NCI NIH HHS: P50 CA127003, P50CA127003

    British journal of cancer 2009;101;3;465-72

  • A gene marker panel covering the Wnt and the Ras-Raf-MEK-MAPK signalling pathways allows to detect gene mutations in 80% of early (UICC I) colon cancer stages in humans.

    Scholtka B, Schneider M, Melcher R, Katzenberger T, Friedrich D, Berghof-Jäger K, Scheppach W and Steinberg P

    Institute of Nutritional Science, University of Potsdam, Nuthetal, Germany.

    Background: Very recently a gene marker panel that allows the mutational analysis of APC, CTNNB1, B-RAF and K-RAS was conceived. The aim of the present study was to use the 4-gene marker panel covering the Wnt and Ras-Raf-MEK-MAPK signalling pathways to determine the percentage of sporadic colorectal carcinomas (CRC) carrying at least one of the four above-mentioned genes in a mutated form alone and/or in combination with microsatellite instability (MSI) and to compare the sensitivity of the gene marker panel used in this study with that of gene marker panels previously reported in the scientific literature.

    Methods: CTNNB1 and B-RAF were screened by PCR-single-strand conformation polymorphism analysis and K-RAS gene mutations by restriction fragment length polymorphism analysis. For the mutational analysis of the APC gene mutation cluster region (codons 1243-1567) direct DNA sequencing was performed. The U.S. National Cancer Institute microsatellite panel (BAT25, BAT26, D2S123, D5S346 and D17S250) was used for MSI analysis.

    Results: It could be shown that about 80% of early stage CRC (UICC stages I and II) and over 90% of CRC in the UICC stage IV carried at least one mutated gene and/or showed MSI. No significant increase in the gene mutation frequencies could be determined when comparing tumours in the UICC stage I with those in UICC stage IV.

    Conclusions: When compared with previously published gene marker panels the 4-gene marker panel used in the present study shows an excellent performance, allowing to detect genetic alterations in 80-90% of human sporadic CRC samples analyzed.

    Cancer epidemiology 2009;33;2;123-9

  • Genetic and molecular diversity of colon cancer hepatic metastases.

    Messick CA, Sanchez J, Dejulius KL, Church JM and Kalady MF

    Department of Colorectal Surgery, Digestive Disease Institute, Cleveland Clinic, Cleveland, OH 44106, USA. messicc@ccf.org

    Background: Colon cancer arises through distinct molecular pathways resulting in diverse tumor populations demonstrated by differences in microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and mutations in oncogenes KRAS and BRAF. Although these molecular differences are well-described for primary neoplasms, the molecular nature of hepatic metastases is not well-characterized. This study seeks to describe molecular characteristics of colon cancer hepatic metastases in terms of oncogenic pathway.

    Methods: Tumor DNA was isolated from fresh frozen hepatic metastases from colon cancer and analyzed for MSI by polymerase chain reaction (PCR)-based microsatellite analysis and for CIMP using MethyLight quantitative PCR. KRAS and BRAF oncogenes were analyzed for DNA mutations. Metastases were classified by their molecular and genetic features. Unfortunately, tissue from the primary neoplasms from these patients were not available

    Results: Thirty patients with liver metastases from colon cancer were studied. Molecular analysis revealed 10% (3/30) were MSI-H, 10% (3/30) were CIMP positive, 33% (10/30) had KRAS mutations, and none had BRAF mutations. Literature describing primary colon cancers reports an incidence of approximately 20% MSI-H, 20% CIMP-positive, 35% KRAS mutants, and 17% BRAF mutants.

    Conclusion: Hepatic metastases from colon cancer, like primary colon adenocarcinomas, show genetic and molecular diversity. Furthermore, hepatic metastases may have a different incidence of MSI and methylation compared with primary neoplasms. These differences could impact treatment decisions.

    Surgery 2009;146;2;227-31

  • Molecular analysis of PIK3CA, BRAF, and RAS oncogenes in periampullary and ampullary adenomas and carcinomas.

    Schönleben F, Qiu W, Allendorf JD, Chabot JA, Remotti HE and Su GH

    Department of Otolaryngology/Head and Neck Surgery, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.

    Background: Mutations of KRAS are known to occur in periampullary and ampullary adenomas and carcinomas. However, nothing is known about NRAS, HRAS, BRAF, and PIK3CA mutations in these tumors. While oncogenic BRAF contributes to the tumorigenesis of both pancreatic ductal adenocarcinoma and intraductal papillary mucinous neoplasms/carcinomas (IPMN/IPMC), PIK3CA mutations were only detected in IPMN/IPMC. This study aimed to elucidate possible roles of BRAF and PIK3CA in the development of ampullary and periampullary adenomas and carcinomas.

    Methods: Mutations of BRAF, NRAS, HRAS, KRAS, and PIK3CA were evaluated in seven adenomas, seven adenomas with carcinoma in situ, and 21 adenocarcinomas of the periampullary duodenal region and the ampulla of Vater. Exons 1 of KRAS; 2 and 3 of NRAS and HRAS; 5, 11, and 15 of BRAF; and 9 and 20 of PIK3CA were examined by direct genomic sequencing.

    Results: In total, we identified ten (28.6%) KRAS mutations in exon 1 (nine in codon 12 and one in codon 13), two missense mutations of BRAF (6%), one within exon 11 (G469A), and one V600E hot spot mutation in exon 15 of BRAF. BRAF mutations were present in two of five periampullary tumors. All mutations appear to be somatic since the same alterations were not detected in the corresponding normal tissues.

    Conclusion: Our data provide evidence that oncogenic properties of KRAS and BRAF but not NRAS, HRAS, and PIK3CA contribute to the tumorigenesis of periampullary and ampullary tumors; BRAF mutations occur more frequently in periampullary than ampullary neoplasms.

    Funded by: NCI NIH HHS: R01 CA109525, R01 CA109525-05, R01CA109525, R21 CA127701, R21 CA127701-01A2, R21CA127701

    Journal of gastrointestinal surgery : official journal of the Society for Surgery of the Alimentary Tract 2009;13;8;1510-6

  • EGFR/KRAS/BRAF mutations in primary lung adenocarcinomas and corresponding locoregional lymph node metastases.

    Schmid K, Oehl N, Wrba F, Pirker R, Pirker C and Filipits M

    Clinical Institute of Pathology and Department of Medicine I, Medical University of Vienna, Waehringer Guertel 18-20, Vienna A-1090, Austria. katharina.schmid@meduniwien.ac.at

    Purpose: The epidermal growth factor receptor (EGFR) and its downstream factors KRAS and BRAF are mutated with different frequencies in non-small cell lung cancer and mutations predict clinical response to EGFR inhibitors. The present study compared the mutational status of EGFR, KRAS, and BRAF in primary tumors with the one in corresponding lymph node metastases.

    Direct bidirectional sequencing of EGFR gene exons 18 to 21, KRAS gene codons 12/13 and 61 to 68, and BRAF exon 15 was done on 96 paired samples of primary lung adenocarcinomas and corresponding locoregional lymph node metastases. In addition, comparative genomic hybridization analyses in two pairs of corresponding primary and metastatic tumor samples with discordant EGFR mutation status were done.

    Results: Mutations in EGFR, KRAS, and BRAF were observed in 7 (7%), 36 (38%), and 2 (2%) patients, respectively. Interestingly, KRAS mutations were observed in two patients with an EGFR mutation. Mutations in primary tumors and lymph node metastases were identical in 1 of 7 (14%) patients in case of EGFR and 11 of 36 (31%) patients in case of KRAS. One patient harbored different KRAS mutations in primary and corresponding metastatic tumors. Comparative genomic hybridization analysis revealed similar patterns of chromosomal changes, strongly supporting a common clonal origin of primary tumors and metastases.

    Conclusions: The possibility of differences in the mutational status of EGFR, KRAS, BRAF between primary tumors and corresponding lymph node metastases should be considered whenever these mutations are used for the selection of patients for EGFR-directed tyrosine kinase inhibitor therapy.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2009;15;14;4554-60

  • BRAF mutation in metastatic colorectal cancer.

    Tol J, Nagtegaal ID and Punt CJ

    The New England journal of medicine 2009;361;1;98-9

  • Detection of KRAS oncogene in peripheral blood as a predictor of the response to cetuximab plus chemotherapy in patients with metastatic colorectal cancer.

    Yen LC, Yeh YS, Chen CW, Wang HM, Tsai HL, Lu CY, Chang YT, Chu KS, Lin SR and Wang JY

    Graduate Institute of Medicine, College of Medicine, College of Medicine, Taiwan.

    Purpose: Previously we developed membrane-arrays as a promising tool to detect circulating tumor cells (CTC) with KRAS oncogene in patients with malignancies. This study was conducted to determinate the predictive values of CTCs with KARS mutation by membrane-arrays for metastatic colorectal cancer patients treated with cetuximab plus chemotherapy.

    Seventy-six metastatic colorectal cancer patients receiving cetuximab plus FOLFIRI or FOLFOX-4 chemotherapy were enrolled. KRAS mutation status in the peripheral blood of these patients was analyzed using membrane-arrays, and KRAS mutation status in tumors was analyzed by DNA sequencing.

    Results: Among 76 metastatic colorectal cancer patients, KRAS mutations in tumors and in peripheral blood were identified in 33 (43.4%) and 30 (39.5%) patients, respectively. The detection sensitivity, specificity, and accuracy of membrane-arrays for CTCs with KRAS oncogene were 84.4%, 95.3%, and 90.8%, respectively, and indeed a highly significant correlation to KRAS mutations in tumors (P < 0.0001) was observed. Forty-five (59.2%) patients responded to cetuximab plus chemotherapy, and 41 and 40 were wild-type KRAS in tumors and peripheral blood, respectively (both P < 0.0001). Patients with tumors that harbor wild-type KRAS are more likely to have a better progression-free survival and overall survival when treated with cetuximab plus chemotherapy (P < 0.0001). Likewise, patients with CTCs of wild-type KRAS in peripheral blood express a better progression-free survival and overall survival when treated with cetuximab plus chemotherapy (P < 0.0001).

    Conclusions: These findings provide evidence that detection of KRAS mutational status in CTCs, by gene expression array, has potential for clinical application in selecting metastatic colorectal cancer patients most likely to benefit from cetuximab therapy.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2009;15;13;4508-13

  • Somatic alterations, metabolizing genes and smoking in rectal cancer.

    Curtin K, Samowitz WS, Wolff RK, Herrick J, Caan BJ and Slattery ML

    Department of Internal Medicine, University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA. karen.curtin@hsc.utah.edu

    Cigarette smoking has been identified as a risk factor for rectal cancer. Our investigation evaluates associations between active and passive smoking and TP53, KRAS2, and BRAF V600E mutations, microsatellite instability (MSI), and CpG Island Methylator Phenotype (CIMP) in rectal tumors. We examine how genetic variants of GSTM1 and NAT2 alter these associations in a population-based, case-control study of 750 incident rectal cancer cases and 1,201 controls. Detailed tobacco exposure data were collected in an extensive questionnaire. DNA from blood was examined for GSTM1 and NAT2 variants. Tumor DNA was assessed to determine TP53 (exons 5-8), KRAS2 (codons 12-13) and BRAF mutations, MSI (BAT26 and TGFbetaRII analysis), and CIMP (methylation of CpG islands in CDKN2A, MLH1, MINT1, MINT2 and MINT31). Cigarette smoking (>20 pack-years, relative to nonsmokers) was associated with increased risk of TP53 mutations (OR = 1.4, 95% CI 1.02-2.0), BRAF mutations (OR = 4.2, 95% CI 1.3-14.2) and MSI (OR = 5.7, 95% CI 1.1-29.8) in rectal tumors. Long-term environmental tobacco smoke (ETS) exposure of >10 hr/wk was associated with increased risk of KRAS2 mutation (OR = 1.5, 95% CI 1.04-2.2). All smoking indicators were suggestive of increased risk in CIMP+ rectal cancer. GSTM1 and NAT2 were generally not associated with rectal tumor alterations; however, we observed an interaction of ETS and NAT2 in TP53-mutated tumors (p < 0.01). Our investigation shows active smoking is associated with increased risk of TP53, BRAF and MSI+ in rectal tumors and is suggestive of increased risk of CIMP+ tumors. ETS may increase risk of KRAS2 mutations; association with TP53 mutations and ETS may be influenced by NAT2.

    Funded by: NCI NIH HHS: CA61757, N01-PC-35141, N01PC35141, R01 CA048998, R01 CA048998-13, R01 CA061757, R01 CA061757-11, R01 CA48998

    International journal of cancer 2009;125;1;158-64

  • A comparison of colon and rectal somatic DNA alterations.

    Slattery ML, Curtin K, Wolff RK, Boucher KM, Sweeney C, Edwards S, Caan BJ and Samowitz W

    Department of Internal Medicine, University of Utah, Salt Lake City, Utah 84108, USA. marty.slattery@hsc.utah.edu

    Purpose: Differences in acquired mutations in colon and rectal tumors may account for differences in risk factors. In this study, we examined similarities and differences in somatic alterations in colon and rectal tumors.

    Methods: Cases were identified from two large population-based case-control studies of colon cancer and rectal cancer. We sequenced Exons 5 to 8 of the p53 gene and Codons 12 and 13 of the Ki-ras gene to identify tumor mutations. Microsatellite instability was determined based on BAT26 and TGFbetaRII analysis; CpG island methylator phenotype was determined based on having two or more of the following markers methylated p16, MLH1, MINT1, MINT2, and MINT31.

    Results: p53 mutations were observed in 39.7% of proximal, 51.0% of distal, and 46.6% of rectal tumors; Ki-ras mutations were observed in 36.0% of proximal, 26.9% of distal, and 30.5% of rectal tumors. Although 40.9% of proximal tumors were considered CpG island methylator phenotype positive (having two or more of five markers methylated), only 12.9% of distal and 11.9% of rectal tumors were CpG island methylator phenotype positive. Likewise, microsatellite instability was observed in 23.7% of proximal and only 3.8% of distal and 2.0% of rectal tumors. More than 50% of distal colon or rectal tumors had only one acquired mutation, whereas only 35.1% of proximal tumors had one mutation. The most common single mutation for colon and rectal tumors was p53 followed by Ki-ras mutations.

    Conclusions: Our findings suggest that unique mutational pathways are involved in the development of most colorectal tumors. Proximal colon cancers are more likely than rectal and distal colon tumors to have microsatellite instability, CpG island methylator phenotype, and Ki-ras mutations, whereas rectal and distal colon tumors are more likely than proximal colon tumors to have a p53 mutation. Overall, rectal and distal colon tumors share similar mutational frequencies which are different from those observed in proximal colon tumors.

    Funded by: NCI NIH HHS: CA48998, CA61757, N01-PC-67000, P30 CA042014, R01 CA048998, R01 CA048998-13, R01 CA061757, R01 CA061757-11, U01 CA048998

    Diseases of the colon and rectum 2009;52;7;1304-11

  • Dominance of EGFR and insignificant KRAS mutations in prediction of tyrosine-kinase therapy for NSCLC patients stratified by tumor subtype and smoking status.

    Pesek M, Benesova L, Belsanova B, Mukensnabl P, Bruha F and Minarik M

    Departments of Pneumology, Faculty Hospital Pilsen, Pilsen, Czech Republic.

    Background: Therapy by tyrosine kinase inhibitors (TKI) has become inevitable in treatment of advanced NSCLC. Mutations in EGFR and KRAS genes have been identified as the main potential predictive and prognostic factors. Here the clinical implications of EGFR/KRAS mutations in patients from two separate trials treated with gefitinib or erlotinib are analysed.

    A total of 360 patients (269 gefitinib and 91 erlotinib) were evaluated. Mutations in EGFR (exon 19 and 21) and KRAS (codons 12 and 13) and their impact on response and survival with respect to tumor subtype and smoking status were assessed.

    Results: Adenocarcinomas revealed 399 days to progression (TTP) and 548 days overall survival (OS) for EGFR mutated vs. 119 days to progression and 137 days survival for non-mutated, p<0.0001 (TTP) and p=0.0001 (OS). No EGFR effect was recorded for squamous cell tumors. For smoking status, both EGFR-mutated smokers and non-smokers profited from TKI therapy. Smokers: 243 vs. 122 days (mutated vs. non-mutated), p=0.0284 (TTP) and 244 vs. 126 days, p=0.0396 (OS); non-smokers: 390 vs. 71 days, p<0.0001, (TTP) and 548 vs. 135 days, p<0.0001 (OS). KRAS mutation in tumors did not result in a poorer prognosis in the subtype-selected groups, nor did it present as a negative factor in smokers.

    Conclusion: EGFR mutations possess statistical significance for a better therapy response and longer survival in all patients with adenocarcinomas (smokers as well as non-smokers). KRAS does not seem an "a priori" negative factor for TKI-based treatment of NSCLC.

    Anticancer research 2009;29;7;2767-73

  • Follow-up study of K-ras mutations in the plasma of patients with pancreatic cancer: correlation with clinical features and carbohydrate antigen 19-9.

    Däbritz J, Preston R, Hänfler J and Oettle H

    Department of Medical Oncology and Hematology, Charité School of Medicine, Campus Virchow-Klinikum, Humboldt University of Berlin, Berlin, Germany. Jan.Daebritz@charite.de

    Objective: We followed up the presence of Kirsten rat sarcoma (K-ras) mutations in plasma DNA and assessed its clinical value in patients with pancreatic cancer.

    Methods: Plasma samples (N = 430) of 56 patients with pancreatic cancer and 13 patients with pancreatitis were analyzed by real-time polymerase chain reaction using peptide nucleic acid-mediated polymerase chain reaction clamping.

    Results: K-ras mutations could be detected in the plasma DNA of 20 patients with cancer (36%). No K-ras mutation was found in the plasma of patients with pancreatitis. In 7 (35%) of 20 patients with lowly or moderately elevated carbohydrate antigen 19.9 (CA 19-9) levels lower than 100 U/mL, the result of the assay was positive for K-ras mutation. The combination of K-ras and CA 19-9 level determination gave a sensitivity for the diagnosis of pancreatic cancer of 91% (40/44) of the patients. Thirteen of 35 patients with pancreatic cancer (102 plasma samples) with elevated CA 19-9 levels (>35 U/mL) and altered K-ras gene showed significant correlation with elevated CA 19-9 levels (P=0.048).

    Conclusions: The summary of our approach of noninvasive, convenient, extremely high-sensitive K-ras mutation analysis in plasma might provide diagnostic and prognostic information to clinicians but will not be sufficient in a standardized early diagnosis of pancreatic carcinoma. The combination with CA 19-9 assay is useful for detection and prognostic evaluation of pancreatic carcinoma.

    Pancreas 2009;38;5;534-41

  • KRAS mutation testing in colorectal cancer.

    Plesec TP and Hunt JL

    Department of Anatomic Pathology, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA. plesect@ccf.org

    In the US, colorectal cancer is the third leading cause of cancer-related death. Approximately 20% of patients present with metastatic disease, and an additional 30% to 40% develop metastasis during the course of their disease. Patients with metastatic colon cancer have a 5-year survival rate of only 11%. Although surgery is the mainstay of treatment for early stage colon cancer, adjuvant treatment is usually used in patients advanced stage disease. In particular, epidermal growth factor receptor (EGFR) inhibitor therapies have emerged as effective treatments in a subset of patients with metastatic colorectal carcinoma. Two anti-EGFR biologics, cetuximab and panitumumab, have been approved by the Food and Drug Administrations for the treatment of refractory metastatic colorectal carcinoma. Mounting evidence has shown that these therapies are ineffective in tumors with mutations of codons 12 and 13 of exon 2 of the KRAS gene. Because of this compelling data, the National Comprehensive Cancer Network and the American Society of Clinical Oncology have recommended determination of KRAS mutation status in all patients with metastatic colorectal cancer who are candidates for anti-EGFR therapy. Anatomic pathologists play an integral role in coordinating the testing for KRAS mutations, as this assay is performed on tissue samples selected by the pathologist. Herein, the authors present an up-to-date review of the biologic, clinical, and laboratory aspects of KRAS mutation testing in colorectal cancer.

    Advances in anatomic pathology 2009;16;4;196-203

  • MGMT and MLH1 promoter methylation versus APC, KRAS and BRAF gene mutations in colorectal cancer: indications for distinct pathways and sequence of events.

    de Vogel S, Weijenberg MP, Herman JG, Wouters KA, de Goeij AF, van den Brandt PA, de Bruïne AP and van Engeland M

    Department of Epidemiology, GROW-School for Oncology and Developmental Biology, Maastricht University, Maastricht, The Netherlands.

    Background: To study how caretaker gene silencing relates to gatekeeper mutations in colorectal cancer (CRC), we investigated whether O6-methylguanine DNA methyltransferase (MGMT) and Human Mut-L Homologue 1 (MLH1) promoter hypermethylation are associated with APC, KRAS and BRAF mutations among 734 CRC patients.

    Methods: We compared MGMT hypermethylation with G:C > A:T mutations in APC and KRAS and with the occurrence of such mutations in CpG or non-CpG dinucleotides in APC. We also compared MLH1 hypermethylation with truncating APC mutations and activating KRAS and BRAF mutations.

    Results: Only 10% of the tumors showed both MGMT and MLH1 hypermethylation. MGMT hypermethylation occurred more frequently in tumors with G:C > A:T KRAS mutations (55%) compared with those without these mutations (38%, P < 0.001). No such difference was observed for G:C > A:T mutations in APC, regardless of whether mutations occurred in CpG or non-CpG dinucleotides. MLH1 hypermethylation was less common in tumors with APC mutations (P = 0.006) or KRAS mutations (P = 0.001), but was positively associated with BRAF mutations (P < 0.001).

    Conclusions: MGMT hypermethylation is associated with G:C > A:T mutations in KRAS, but not in APC, suggesting that MGMT hypermethylation may succeed APC mutations but precedes KRAS mutations in colorectal carcinogenesis. MLH1-hypermethylated tumors harbor fewer APC and KRAS mutations and more BRAF mutations, suggesting that they develop distinctly from an MGMT methylator pathway.

    Annals of oncology : official journal of the European Society for Medical Oncology / ESMO 2009;20;7;1216-22

  • Mutation pattern of K-ras gene in colorectal cancer patients of Kashmir: a report.

    Sameer AS, Chowdhri NA, Abdullah S, Shah ZA and Siddiqi MA

    Department of Clinical Biochemistry, Sher-I-Kashmir Institute of Medical Sciences, Soura, Srinagar, Kashmir - 190 011, India.

    Colorectal cancer (CRC) is one of the leading malignancies worldwide. CRC has been reported to show geographical variation in its incidence, even within areas of ethnic homogeneity. The aim of this study is to identify K-ras gene mutations in CRC patients among the Kashmiri population, and to assess whether they are linked with the clinicopathological parameters.

    Paired tumor and normal tissue samples were collected from a consecutive series of 53 patients undergoing resective surgery for CRC. In addition blood was also collected from all the cases for ruling out germline mutation.

    Results: Colorectal patients, 22.64% (12 of 53), presented with mutations in K-ras constituting 13 missense mutations out of which 11 were G-->A transition, one G-->C transversion, and one G-->T transversion. 61.5% percent of the mutations occurred in codon 12 and 38.5% in codon 13. One tumor contained missense mutations in both codons. K-ras mutations were significantly associated with advanced Dukes' stage (P < 0.05) and positive lymph node status (P < 0.05). Moreover Codon 12 K-ras mutations were associated with mucinous histotype (P < 0.05). Comparison of the mutation profile with other high-risk areas reflected both mucinous histotype differences and similarities indicating coexposure to a unique set of risk factors.

    Conclusion: Mutation of the K-ras gene is one of the commonest genetic changes in the development of human CRC, but it occurs in a rather low frequency in Kashmiri population.

    Indian journal of cancer 2009;46;3;219-25

  • Novel susceptibility loci for second primary tumors/recurrence in head and neck cancer patients: large-scale evaluation of genetic variants.

    Wu X, Spitz MR, Lee JJ, Lippman SM, Ye Y, Yang H, Khuri FR, Kim E, Gu J, Lotan R and Hong WK

    Department of Epidemiology, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.

    This study was aimed to identify novel susceptibility variants for second primary tumor (SPT) or recurrence in curatively treated early-stage head and neck squamous cell carcinoma (HNSCC) patients. We constructed a custom chip containing a comprehensive panel of 9,645 chromosomal and mitochondrial single nucleotide polymorphisms (SNP) representing 998 cancer-related genes selected by a systematic prioritization schema. Using this chip, we genotyped 150 early-stage HNSCC patients with and 300 matched patients without SPT/recurrence from a prospectively conducted randomized trial and assessed the association of these SNPs with risk of SPT/recurrence. Individually, six chromosomal SNPs and seven mitochondrial SNPs were significantly associated with risk of SPT/recurrence after adjustment for multiple comparisons. A strong gene-dosage effect was observed when these SNPs were combined, as evidenced by a progressively increasing SPT/recurrence risk as the number of unfavorable genotypes increased (P for trend < 1.00 x 10(-20)). Several polygenic analyses suggest an important role of interconnected functional network and gene-gene interaction in modulating SPT/recurrence. Furthermore, incorporation of these genetic markers into a multivariate model improved significantly the discriminatory ability over the models containing only clinical and epidemiologic variables. This is the first large-scale systematic evaluation of germ-line genetic variants for their roles in HNSCC SPT/recurrence. The study identified several promising susceptibility loci and showed the cumulative effect of multiple risk loci in HNSCC SPT/recurrence. Furthermore, this study underscores the importance of incorporating germ-line genetic variation data with clinical and risk factor data in constructing prediction models for clinical outcomes.

    Funded by: NCI NIH HHS: CA52051, CA86390, CA97007, P01 CA052051, P01 CA052051-10, P50 CA097007, P50 CA097007-09, U01 CA086390, U01 CA086390-05

    Cancer prevention research (Philadelphia, Pa.) 2009;2;7;617-24

  • V600E BRAF mutations are alternative early molecular events in a subset of KIT/PDGFRA wild-type gastrointestinal stromal tumours.

    Agaimy A, Terracciano LM, Dirnhofer S, Tornillo L, Foerster A, Hartmann A and Bihl MP

    Institute of Pathology, Friedrich-Alexander-University, Erlangen, Germany. abbas.agaimy@uk-erlangen.de

    Background: A small subset (10-15%) of gastrointestinal stromal tumours (GISTs) lack mutations in KIT and PDGFRA (wild-type GIST). Recently, a novel BRAF exon 15 mutation (V600E) was detected in imatinib-naive wild-type high-risk intestinal GISTs (4%). However, the frequency and distribution of BRAF mutations within the spectrum of GISTs, and whether they might represent secondary events acquired during tumour progression, remain unknown.

    Methods: 69 GISTs (39 KIT mutants, 2 PDGFRA mutants and 28 wild-type) were analysed for mutations in BRAF exon 15 and KRAS exon 2. To assess the stage at which these mutations might occur in GIST, a considerable number of incidental gastric (n = 23) and intestinal (n = 2) tumours were included.

    Results: BRAF mutations (V600E) were detected in 2 of 28 wild-type GISTs (7%), but in none of the 41 KIT/PDGFRA mutants. No KRAS mutation was detected. The two BRAF-mutated GISTs measured 4 mm in diameter and originated in the gastric body and the jejunum in two men (mean age, 76 years). Both tumours were mitotically inactive KIT-positive spindle-cell GISTs that were indistinguishable histologically from their more common KIT-mutated counterparts.

    Conclusion: BRAF mutations represent an alternative molecular pathway in the early tumorigenesis of a subset of KIT/PDGFRA wild-type GISTs and are per se not associated with a high risk of malignancy. Mutations in KIT, PDGFRA and BRAF were mutually exclusive in this study. Results from this and a previous study indicate that BRAF-mutated GISTs show a predilection for the small bowel (four of five tumours), but this needs further evaluation in larger studies.

    Journal of clinical pathology 2009;62;7;613-6

  • A novel method, digital genome scanning detects KRAS gene amplification in gastric cancers: involvement of overexpressed wild-type KRAS in downstream signaling and cancer cell growth.

    Mita H, Toyota M, Aoki F, Akashi H, Maruyama R, Sasaki Y, Suzuki H, Idogawa M, Kashima L, Yanagihara K, Fujita M, Hosokawa M, Kusano M, Sabau SV, Tatsumi H, Imai K, Shinomura Y and Tokino T

    Department of Molecular Biology, Cancer Research Institute, Sapporo Medical University, Sapporo, Japan. mita@sapmed.ac.jp

    Background: Gastric cancer is the third most common malignancy affecting the general population worldwide. Aberrant activation of KRAS is a key factor in the development of many types of tumor, however, oncogenic mutations of KRAS are infrequent in gastric cancer. We have developed a novel quantitative method of analysis of DNA copy number, termed digital genome scanning (DGS), which is based on the enumeration of short restriction fragments, and does not involve PCR or hybridization. In the current study, we used DGS to survey copy-number alterations in gastric cancer cells.

    Methods: DGS of gastric cancer cell lines was performed using the sequences of 5000 to 15000 restriction fragments. We screened 20 gastric cancer cell lines and 86 primary gastric tumors for KRAS amplification by quantitative PCR, and investigated KRAS amplification at the DNA, mRNA and protein levels by mutational analysis, real-time PCR, immunoblot analysis, GTP-RAS pull-down assay and immunohistochemical analysis. The effect of KRAS knock-down on the activation of p44/42 MAP kinase and AKT and on cell growth were examined by immunoblot and colorimetric assay, respectively.

    Results: DGS analysis of the HSC45 gastric cancer cell line revealed the amplification of a 500-kb region on chromosome 12p12.1, which contains the KRAS gene locus. Amplification of the KRAS locus was detected in 15% (3/20) of gastric cancer cell lines (8-18-fold amplification) and 4.7% (4/86) of primary gastric tumors (8-50-fold amplification). KRAS mutations were identified in two of the three cell lines in which KRAS was amplified, but were not detected in any of the primary tumors. Overexpression of KRAS protein correlated directly with increased KRAS copy number. The level of GTP-bound KRAS was elevated following serum stimulation in cells with amplified wild-type KRAS, but not in cells with amplified mutant KRAS. Knock-down of KRAS in gastric cancer cells that carried amplified wild-type KRAS resulted in the inhibition of cell growth and suppression of p44/42 MAP kinase and AKT activity.

    Conclusion: Our study highlights the utility of DGS for identification of copy-number alterations. Using DGS, we identified KRAS as a gene that is amplified in human gastric cancer. We demonstrated that gene amplification likely forms the molecular basis of overactivation of KRAS in gastric cancer. Additional studies using a larger cohort of gastric cancer specimens are required to determine the diagnostic and therapeutic implications of KRAS amplification and overexpression.

    BMC cancer 2009;9;198

  • Fast simultaneous detection of K-RAS mutations in colorectal cancer.

    Chang YS, Yeh KT, Chang TJ, Chai C, Lu HC, Hsu NC and Chang JG

    Department of Laboratory Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan. 970494@ms.kmuh.org.tw

    Background: RAS genes acquire the most common somatic gain-of-function mutations in human cancer, and almost all of these mutations are located at codons 12, 13, 61, and 146.

    Methods: We present a method for detecting these K-RAS hotspot mutations in 228 cases of colorectal cancer. The protocol is based on the multiplex amplification of exons 2, 3 and 4 in a single tube, followed by primer extension of the PCR products using various sizes of primers to detect base changes at codons 12, 13, 61 and 146. We compared the clinicopathological data of colorectal cancer patients with the K-RAS mutation status.

    Results: K-RAS mutation occurred in 36% (83/228) of our colorectal cancer cases. Univariate analysis revealed a significant association between K-RAS mutation at codon 12 of exon 2 and poor 5-year survival (p = 0.023) and lymph node involvement (p = 0.048). Also, K-RAS mutation at codon 13 of exon 2 correlates with the size of the tumor (p = 0.03). Multivariate analysis adjusted for tumor size, histologic grade, and lymph node metastasis also indicated K-RAS mutations at codon 12 and 13 of exon 2 correlate significantly with overall survival (p = 0.002 and 0.025). No association was observed between codon 61 and 146 and clinicopathological features.

    Conclusion: We demonstrated a simple and fast way to identify K-RAS mutation.

    BMC cancer 2009;9;179

  • Mutational profile of advanced primary and metastatic radioactive iodine-refractory thyroid cancers reveals distinct pathogenetic roles for BRAF, PIK3CA, and AKT1.

    Ricarte-Filho JC, Ryder M, Chitale DA, Rivera M, Heguy A, Ladanyi M, Janakiraman M, Solit D, Knauf JA, Tuttle RM, Ghossein RA and Fagin JA

    Human Oncology and Pathogenesis Program and Departments of Medicine and Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA.

    Patients with poorly differentiated thyroid cancers (PDTC), anaplastic thyroid cancers (ATC), and radioactive iodine-refractory (RAIR) differentiated thyroid cancers have a high mortality, particularly if positive on [(18)F]fluorodeoxyglucose (FDG)-positron emission tomography (PET). To obtain comprehensive genetic information on advanced thyroid cancers, we designed an assay panel for mass spectrometry genotyping encompassing the most significant oncogenes in this disease: 111 mutations in RET, BRAF, NRAS, HRAS, KRAS, PIK3CA, AKT1, and other related genes were surveyed in 31 cell lines, 52 primary tumors (34 PDTC and 18 ATC), and 55 RAIR, FDG-PET-positive recurrences and metastases (nodal and distant) from 42 patients. RAS mutations were more prevalent than BRAF (44 versus 12%; P = 0.002) in primary PDTC, whereas BRAF was more common than RAS (39 versus 13%; P = 0.04) in PET-positive metastatic PDTC. BRAF mutations were highly prevalent in ATC (44%) and in metastatic tumors from RAIR PTC patients (95%). Among patients with multiple metastases, 9 of 10 showed between-sample concordance for BRAF or RAS mutations. By contrast, 5 of 6 patients were discordant for mutations of PIK3CA or AKT1. AKT1_G49A was found in 9 specimens, exclusively in metastases. This is the first documentation of AKT1 mutation in thyroid cancer. Thus, RAIR, FDG-PET-positive metastases are enriched for BRAF mutations. If BRAF is mutated in the primary, it is likely that the metastases will harbor the defect. By contrast, absence of PIK3CA/AKT1 mutations in one specimen may not reflect the status at other sites because these mutations arise during progression, an important consideration for therapies directed at phosphoinositide 3-kinase effectors.

    Funded by: NCI NIH HHS: CA50706, P30 CA008748, R01 CA050706, R01 CA050706-20, R01 CA072597

    Cancer research 2009;69;11;4885-93

  • PTEN expression and KRAS mutations on primary tumors and metastases in the prediction of benefit from cetuximab plus irinotecan for patients with metastatic colorectal cancer.

    Loupakis F, Pollina L, Stasi I, Ruzzo A, Scartozzi M, Santini D, Masi G, Graziano F, Cremolini C, Rulli E, Canestrari E, Funel N, Schiavon G, Petrini I, Magnani M, Tonini G, Campani D, Floriani I, Cascinu S and Falcone A

    Department of Oncology, Azienda USL 6, Istituto Toscano Tumori, Livorno, Italy. fotiosloupakis@gmail.com

    Purpose: PTEN, AKT, and KRAS are epidermal growth factor receptor (EGFR) downstream regulators. KRAS mutations confer resistance to cetuximab. This retrospective study investigated the role of PTEN loss, AKT phosphorylation, and KRAS mutations on the activity of cetuximab plus irinotecan in patients with metastatic colorectal cancer (mCRC).

    A cohort of patients with irinotecan-refractory mCRC who were treated with cetuximab plus irinotecan was tested for PTEN immunoreactivity (ie, immunohistochemistry; IHC), pAKT IHC, and KRAS mutations. Analyses were performed both on primary tumors and on related metastases, and the association among IHC, mutational results, and treatment outcomes was investigated.

    Results: One-hundred two patients were eligible. Ninety-six primary tumors, 59 metastases, and 53 paired samples were available. Forty-nine primary tumors (58% of assessable samples) had a preserved PTEN expression (PTEN-positive), whereas 35 (40% of assessable samples) were pAKT-positive. Levels of concordance between primary tumors and metastases were 60%, 68%, and 95% for PTEN, pAKT, and KRAS, respectively. PTEN status on primary tumors and pAKT status both on primary tumors and on metastases did not predict response or progression-free survival (PFS). On metastases, 12 (36%) of 33 patients with PTEN-positive tumors were responders compared with one (5%) of 22 who had PTEN-negative tumors (P = .007). The median PFS of patients with PTEN-positive metastases was 4.7 months compared with 3.3 months for those with PTEN-negative metastases (hazard ratio [HR], 0.49; P = .005). Patients with PTEN-positive metastases and KRAS wild type had longer PFS compared with other patients (5.5 months v 3.8 months; HR, 0.42; P = .001).

    Conclusion: PTEN loss in metastases may be predictive of resistance to cetuximab plus irinotecan. The combination of PTEN IHC and KRAS mutational analyses could help to identify a subgroup of patients with mCRC who have higher chances of benefiting from EGFR inhibition.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2009;27;16;2622-9

  • A let-7 microRNA-binding site polymorphism in the KRAS 3' UTR is associated with reduced survival in oral cancers.

    Christensen BC, Moyer BJ, Avissar M, Ouellet LG, Plaza SL, McClean MD, Marsit CJ and Kelsey KT

    Department of Pathology and Laboratory Medicine, Center for Environmental Health and Technology, Brown University, Providence, RI 02912, USA.

    MicroRNA (miRNA)-binding site polymorphisms that could contribute to disease risk and prognosis are rapidly being identified and investigated as this genetic variation may have a potentially profound impact on human health. A recently described variant allele in the KRAS 3' untranslated region that arises in the let-7 miRNA complementary site (KRAS-LCS6) and leads to increased KRAS expression in lung cancer was examined for its association with the occurrence of head and neck squamous cell carcinoma (HNSCC). We examined the prevalence of the KRAS-LCS6 variant allele in a population-based case-control study of HNSCC to determine if this KRAS-LCS6 genotype was associated with disease occurrence and patient survival. Although the KRAS-LCS6 variant genotype was not associated with the overall risk of HNSCC, cases with the KRAS-LCS6 variant genotype had significantly reduced survival [hazard ratio (HR), 1.6; 95% confidence interval (CI), 1.0-2.5] in models controlled for confounders of survival. This risk was greatest in cases of oral cavity carcinoma (HR, 2.7; 95% CI, 1.4-5.3). These data demonstrate that cases with the KRAS-LCS6 variant have significantly reduced survival time and suggest that this variant may alter the phenotype or therapeutic response of this disease.

    Funded by: NCI NIH HHS: R01 CA078609, R01 CA100679, R01CA078609, R01CA100679; NIEHS NIH HHS: T32ES007272

    Carcinogenesis 2009;30;6;1003-7

  • The miR-18a* microRNA functions as a potential tumor suppressor by targeting on K-Ras.

    Tsang WP and Kwok TT

    Department of Biochemistry, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.

    The Ras proto-oncogene mediates a wide variety of cellular events and is frequently mutated in cancer. MicroRNAs (miRNAs) may regulate the development of cancer through their effect on the target genes. In the search of miRNAs that target on Ras, miR-18a* is the first time confirmed to target on K-Ras and furthermore not on N- and H-Ras. miR-18a* repression by transfection with anti-miR-18a* inhibitor increased the K-Ras expression as well as the luciferase activity of a reporter construct containing the 3'-untranslated region of K-Ras messenger RNA. Furthermore, the miR-18a* repression also increased the cell proliferation and promoted the anchorage-independent growth in soft agar of human squamous carcinoma A431 cells, colon adenocarcinoma HT-29 cells and fetal hepatic WRL-68 cells. On the other hand, ectopic expression of miR-18a* by transfection with miR-18a* precursor suppressed K-Ras expression, cell proliferation and anchorage-independent growth of A431 cells. The increase in cell proliferation and anchorage-independent growth upon miR-18a* repression was, however, rendered by the Ras inhibitor farnesylthiosalicylic acid. In conclusion, miR-18a* may function as a tumor suppressor by targeting on K-Ras. Therefore, the miRNA may also be a potential therapeutic agent or target for cancer therapy.

    Carcinogenesis 2009;30;6;953-9

  • Endoscopic ultrasound-guided fine-needle aspiration biopsy coupled with KRAS mutation assay to distinguish pancreatic cancer from pseudotumoral chronic pancreatitis.

    Bournet B, Souque A, Senesse P, Assenat E, Barthet M, Lesavre N, Aubert A, O'Toole D, Hammel P, Levy P, Ruszniewski P, Bouisson M, Escourrou J, Cordelier P and Buscail L

    Department of Gastroenterology and INSERM U858, University of Toulouse, CHU Rangueil, Toulouse, France.

    Differential diagnosis between pancreatic adenocarcinoma (PADC) and pseudotumoral forms of chronic pancreatitis remains difficult. Mutation of KRAS oncogene is present in 75% to 95% of PADC. This study aimed to evaluate whether the combined analysis of KRAS mutation with cytopathological findings from endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS-FNAB) might improve discrimination between PADC and chronic pancreatitis.

    This prospective multicenter study included 178 patients with solid pancreatic masses (men 104, women 74; mean age 64.5 years). Cytopathological examination and KRAS mutation analysis (codon-12 and codon-13, restriction fragment length polymorphism [RFLP] and direct sequencing) were performed on EUS-FNAB material. Final diagnoses were obtained on EUS-FNAB analysis and/or a second biopsy and/or clinical follow-up and/or surgery: PADC, n = 129; chronic pancreatitis, n = 27; other pancreatic neoplasms, n = 16; and benign lesions, n = 6.

    Results: KRAS status analysis was successful in all EUS-FNAB samples. Codon-12 KRAS point mutation was found in 66% of PADC samples. No case of chronic pancreatitis displayed KRAS mutation. Sensitivity, specificity, positive and negative predictive values, and overall accuracy of cytopathology alone for diagnosis of PADC versus chronic pancreatitis were 83%, 100%, 100%, 56% and 86%, respectively. When KRAS mutation analysis was combined with cytopathology, these values reached 88%, 100%, 100%, 63% and 90% respectively.

    Conclusion: Although the value of KRAS analysis in addition to EUS-FNAB is limited for distinguishing pancreatic mass lesions, when chronic pancreatitis presented as a pseudotumor a negative finding (wild-type KRAS), was useful in strongly suggesting a benign lesion.

    Endoscopy 2009;41;6;552-7

  • Lack of KRAS and BRAF mutation in renal cell carcinoma.

    Gattenlöhner S, Etschmann B, Riedmiller H and Müller-Hermelink HK

    European urology 2009;55;6;1490-1

  • Lifetime history of alcohol consumption and K-ras mutations in pancreatic ductal adenocarcinoma.

    Crous-Bou M, Porta M, López T, Jariod M, Malats N, Morales E, Guarner L, Rifà J, Carrato A, Real FX and PANKRAS II Study Group

    Institut Municipal d'Investigació Mèdica, Barcelona, Spain.

    Background: In pancreatic ductal adenocarcinoma (PDA), evidence on the etiopathogenic role of alcohol consumption in the occurrence of K-ras mutations is scant, and the role of alcohol in pancreatic carcinogenesis is not well established. We analyzed the relation between lifetime consumption of alcohol and mutations in codon 12 of the K-ras oncogene in patients with PDA.

    Methods: Incident cases of PDA were prospectively identified and interviewed face-to-face during hospital admission about lifetime alcohol consumption and other lifestyle factors. Logistic regression was used to compare PDA cases (N = 107) with mutated and wild-type K-ras tumors (case-case study).

    Results: Mutated cases were moderate or heavy drinkers more frequently than wild-type cases: the odds ratio adjusted by age, sex, smoking, and history of pancreatitis (ORa) was 3.18 (95% confidence interval: 1.02-9.93; P = 0.046). Total grams of alcohol and years of consumption were higher in mutated than in wild-type cases: the ORa for lifetime alcohol consumption over 507,499 g was 3.35 (95% CI: 0.81-13.88); and for more than 40 years of alcohol consumption it was 4.47 (95% CI: 1.05-19.02). Age at onset of alcohol consumption and years of abstinence were also associated with the presence of K-ras mutations. There were no significant differences in alcohol dependency.

    Conclusions: Alcohol consumption is weakly associated with an increased risk of having a K-ras mutated PDA. To confirm or to refute the hypothesis that ethanol, acetaldehyde or other alcohol-related substances might influence the acquisition or persistence of K-ras mutations in the pancreatic epithelium, large and unselected studies are warranted.

    Funded by: PHS HHS: 04-C-N272

    Environmental and molecular mutagenesis 2009;50;5;421-30

  • Methylation of estrogen receptor 1 in colorectal adenomas is not age-dependent, but is correlated with K-ras mutation.

    Horii J, Hiraoka S, Kato J, Saito S, Harada K, Fujita H, Kaji E and Yamamoto K

    Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.

    The promoter region of estrogen receptor 1 (ESR1) has been shown to be methylated in normal colorectal mucosa in an age-dependent manner. However, the methylation of this region in colorectal tumors has not sufficiently been investigated. The methylation status of ESR1 in 105 colorectal adenoma tissues was examined by MethyLight and presented as the percentage of methylated references (PMR). Factors that affect the PMR of ESR1 in adenomas were determined using parameters including patient age, sex, past history of malignancy, family history of colorectal cancer, smoking and drinking habits, clinical characteristics of adenomas (location, size, macroscopic appearance, and histology), and K-ras mutation. Multiple linear regression revealed that the PMR was not correlated with patient age. K-ras mutation was significantly correlated with the higher methylation status of ESR1 in adenoma (t-value = 3.21, P = 0.0018), whereas alcohol exposure was significantly correlated with lower methylation status (t-value = -2.37, P = 0.02). Because methylation of O6-methylguanine DNA methyltransferase (MGMT) has been reported to be correlated with K-ras G-to-A transition, methylation of ESR1 was compared with that of MGMT with regard to K-ras mutation. Contrary to expectations, methylation of MGMT was not significantly correlated with K-ras G-to-A transition, but that of ESR1 was strongly correlated with K-ras G-to-A transition. Thus, the methylation status of ESR1 in adenomas was not correlated with patient age, but was associated with K-ras mutation, suggesting that methylation of ESR1 in tumors functions differently from that in normal colon mucosa.

    Cancer science 2009;100;6;1005-11

  • Mutational analysis of the BRAF, RAS and EGFR genes in human adrenocortical carcinomas.

    Kotoula V, Sozopoulos E, Litsiou H, Fanourakis G, Koletsa T, Voutsinas G, Tseleni-Balafouta S, Mitsiades CS, Wellmann A and Mitsiades N

    Department of Pathology, School of Medicine, Aristotle University of Thessaloniki, University Campus, Thessaloniki 54006, Greece. vkotoula@auth.gr

    The serine/threonine kinase B-Raf plays a key role in the Ras/Raf/MEK/ERK pathway that relays extracellular signals for cell proliferation and survival. Several types of human malignancies harbor activating BRAF mutations, most frequently a V600E substitution. The epidermal growth factor receptor (EGFR), a transmembrane tyrosine kinase (TK) receptor that mediates proliferation and survival signaling, is expressed in a wide variety of normal and neoplastic tissues. EGFR inhibitors have produced objective responses in patients with non-small cell lung carcinomas harboring activating EGFR TK domain somatic mutations. We evaluated the presence of mutations in BRAF (exons 11 and 15), KRAS (exons 1 and 2), NRAS (exons 1 and 2), and EGFR (exons 18-21) in adrenal carcinomas (35 tumor specimens and two cell lines) by DNA sequencing. BRAF mutations were found in two carcinomas (5.7%). Four carcinomas (11.4%) carried EGFR TK domain mutations. One specimen carried a KRAS mutation, and another carried two NRAS mutations. No mutations were found in the two adrenocortical cell lines. BRAF- and EGFR-mutant tumor specimens exhibited stronger immunostaining for the phosphorylated forms of the MEK and ERK kinases than their wild-type counterparts. EGFR-mutant carcinomas exhibited increased phosphorylation of EGFR (Tyr 992) compared with wild-type carcinomas. We conclude that BRAF, RAS, and EGFR mutations occur in a subset of human adrenocortical carcinomas. Inhibitors of the Ras/Raf/MEK/ERK and EGFR pathways represent candidate targeted therapies for future clinical trials in carefully selected patients with adrenocortical carcinomas harboring respective activating mutations.

    Endocrine-related cancer 2009;16;2;565-72

  • A genome-wide RNAi screen identifies multiple synthetic lethal interactions with the Ras oncogene.

    Luo J, Emanuele MJ, Li D, Creighton CJ, Schlabach MR, Westbrook TF, Wong KK and Elledge SJ

    Howard Hughes Medical Institute and Department of Genetics, Harvard Medical School, Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA.

    Oncogenic mutations in the small GTPase Ras are highly prevalent in cancer, but an understanding of the vulnerabilities of these cancers is lacking. We undertook a genome-wide RNAi screen to identify synthetic lethal interactions with the KRAS oncogene. We discovered a diverse set of proteins whose depletion selectively impaired the viability of Ras mutant cells. Among these we observed a strong enrichment for genes with mitotic functions. We describe a pathway involving the mitotic kinase PLK1, the anaphase-promoting complex/cyclosome, and the proteasome that, when inhibited, results in prometaphase accumulation and the subsequent death of Ras mutant cells. Gene expression analysis indicates that reduced expression of genes in this pathway correlates with increased survival of patients bearing tumors with a Ras transcriptional signature. Our results suggest a previously underappreciated role for Ras in mitotic progression and demonstrate a pharmacologically tractable pathway for the potential treatment of cancers harboring Ras mutations.

    Funded by: Howard Hughes Medical Institute; NCI NIH HHS: P30 CA125123, P50 CA090578, R01 CA122794; NIA NIH HHS: R01 AG2400401

    Cell 2009;137;5;835-48

  • Microsatellite instability, mismatch repair deficiency, and BRAF mutation in treatment-resistant germ cell tumors.

    Honecker F, Wermann H, Mayer F, Gillis AJ, Stoop H, van Gurp RJ, Oechsle K, Steyerberg E, Hartmann JT, Dinjens WN, Oosterhuis JW, Bokemeyer C and Looijenga LH

    Department of Oncology, University Medical Center Hamburg- Eppendorf, Hamburg, Germany.

    Purpose: Mismatch repair (MMR) deficiency and microsatellite instability (MSI) are associated with cisplatin resistance in human germ cell tumors (GCTs). BRAF mutation (V600E) is found in MSI colorectal cancers. The role of RAS/RAF pathway mutations in GCT treatment response is unknown.

    Two patient cohorts were investigated: 100 control GCTs (50 seminomas and 50 nonseminomas) and 35 cisplatin-based chemotherapy-resistant GCTs. MMR proteins were analyzed by immunohistochemistry, and eight microsatellite loci were examined for MSI. Tumors were assessed for specific BRAF and KRAS mutations.

    Results: Resistant tumors showed a higher incidence of MSI than controls: 26% versus 0% in two or more loci (P < .0001). All resistant tumors were wild-type KRAS, and two controls (2%) contained a KRAS mutation. There was a significantly higher incidence of BRAF V600E mutation in resistant tumors compared with controls: 26% versus 1% (P < .0001). BRAF mutations were highly correlated with MSI (P = .006), and MSI and mutated BRAF were correlated with weak or absent staining for hMLH1 (P = .017 and P = .008). Low or absent staining of hMLH1 was correlated with promoter hypermethylation (P < .001). Tumors lacking expression of hMLH1 or MSH6 were significantly more frequent in resistant GCTs than in controls (P = .001 and 0.0036, respectively). Within the subgroup of resistant tumors, patients with MSI showed a trend to longer progression-free survival (P = .068).

    Conclusion: We report for the first time a correlation between a gene mutation--BRAF V600E--and cisplatin resistance in nonseminomatous GCTs. Furthermore, a correlation between MMR deficiency, MSI, and treatment failure is confirmed.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2009;27;13;2129-36

  • PIK3CA mutations are not a major determinant of resistance to the epidermal growth factor receptor inhibitor cetuximab in metastatic colorectal cancer.

    Prenen H, De Schutter J, Jacobs B, De Roock W, Biesmans B, Claes B, Lambrechts D, Van Cutsem E and Tejpar S

    Department of Digestive Oncology, University Hospital Gasthuisberg, Leuven, Belgium.

    Purpose: It has been reported that activating KRAS mutations negatively affect response to anti-epidermal growth factor receptor (EGFR) monoclonal antibodies in metastatic colorectal cancer. The mutation status of signaling molecules downstream of the EGFR target is thus crucial to predict clinical benefit to EGFR-targeted therapies. Other mechanisms of resistance to EGFR inhibitors could involve activating mutations of the other main EGFR effector pathway, i.e., the PI3K/PTEN/AKT pathway.

    We analyzed the PIK3CA and KRAS mutation status in a large group (n = 200) of chemorefractory metastatic colorectal cancers treated with cetuximab (Erbitux) in monotherapy or in combination with irinotecan, and correlated the mutation status with outcome.

    Results: Twenty-three (12%) of the 200 samples carried 1 of the PIK3CA mutations included in our assay. We found no correlation between the presence of a PIK3CA mutation and impaired response to cetuximab.

    Conclusions: Our findings do not provide any evidence for a strong role of PIK3CA mutations as a single marker in determining response to cetuximab in chemorefractory metastatic colorectal cancer.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2009;15;9;3184-8

  • The importance of KRAS mutations and EGF61A>G polymorphism to the effect of cetuximab and irinotecan in metastatic colorectal cancer.

    Garm Spindler KL, Pallisgaard N, Rasmussen AA, Lindebjerg J, Andersen RF, Crüger D and Jakobsen A

    Department of Oncology, Danish Colorectal Cancer Group South, Vejle Hospital, Vejle, Denmark.

    Background: The effect of anti-epidermal growth factor receptor (EGFR) antibodies (mAb) in metastatic colorectal cancer seems limited to KRAS wild-type (wt) tumours, but still a major fraction of KRASwt patients are nonresponders and supplementary selection criteria are needed. We investigated methodological aspects of KRAS testing and the predictive and prognostic value of KRAS status combined with three EGFR-related gene polymorphisms [single-nucleotide polymorphisms (SNPs)] in patients treated with cetuximab and irinotecan.

    The study included 71 patients referred to third-line cetuximab-irinotecan. Blood samples were analysed for SNPs. KRAS analysis was carried out by sequencing analysis and quantitative PCR (DxS kit) in primary tumour and distant metastases.

    Results: There was a clear correlation between KRAS status in primary tumours and metastasis. The DxS kit presented the highest sensitivity. Response was confined to KRASwt patients (40% response rate versus 0%, P < 0.1(-3)), which translated into a significant difference in PFS. The EGF61A>G polymorphism showed relation to clinical outcome. A combined biomarker analysis showed a 19% progression rate in KRASwt-EGF61 homozygote patients and 60% in the EGF61A/G patients (P = 0.006) and a significant increase in overall survival (17.1 versus 5.9 months, log-rank, P = 0.002).

    Conclusion: The combined biomarker analysis maybe an attractive approach to selection of patients for third-line treatment including anti-EGFR mAbs.

    Annals of oncology : official journal of the European Society for Medical Oncology / ESMO 2009;20;5;879-84

  • Activation of RAS family genes in urothelial carcinoma.

    Boulalas I, Zaravinos A, Karyotis I, Delakas D and Spandidos DA

    Department of Urology, Asklipieio General Hospital, Voula, Athens, Greece.

    Purpose: Bladder cancer is the fifth most common malignancy in men in Western society. We determined RAS codon 12 and 13 point mutations and evaluated mRNA expression levels in transitional cell carcinoma cases.

    Samples from 30 human bladder cancers and 30 normal tissues were analyzed by polymerase chain reaction/restriction fragment length polymorphism and direct sequencing to determine the occurrence of mutations in codons 12 and 13 of RAS family genes. Moreover, we used real-time reverse transcriptase-polymerase chain reaction to evaluate the expression profile of RAS genes in bladder cancer specimens compared to that in adjacent normal tissues.

    Results: Overall H-RAS mutations in codon 12 were observed in 9 tumor samples (30%). Two of the 9 patients (22%) had invasive bladder cancer and 7 (77%) had noninvasive bladder cancer. One H-RAS mutation (11%) was homozygous and the remaining 89% were heterozygous. All samples were WT for K and N-RAS oncogenes. Moreover, 23 of 30 samples (77%) showed over expression in at least 1 RAS family gene compared to adjacent normal tissue. K and N-RAS had the highest levels of over expression in bladder cancer specimens (50%), whereas 27% of transitional cell carcinomas demonstrated H-RAS over expression relative to paired normal tissues.

    Conclusions: Our results underline the importance of H-RAS activation in human bladder cancer by codon 12 mutations. Moreover, they provide evidence that increased expression of all 3 RAS genes is a common event in bladder cancer that is associated with disease development.

    The Journal of urology 2009;181;5;2312-9

  • Adenosquamous carcinoma of the pancreas harbors KRAS2, DPC4 and TP53 molecular alterations similar to pancreatic ductal adenocarcinoma.

    Brody JR, Costantino CL, Potoczek M, Cozzitorto J, McCue P, Yeo CJ, Hruban RH and Witkiewicz AK

    Department of Surgery, Thomas Jefferson University, Philadelphia, PA, USA.

    Adenosquamous carcinoma of the pancreas is one of the most aggressive forms of pancreatic cancer. Molecular characterizations of this rare tumor subtype are sparse. Understanding the common molecular and pathologic features of pancreatic adenosquamous carcinomas could provide critical information for identifying therapeutic targets. Herein, we analyzed the pathologic and molecular features of our series of eight pancreatic adenosquamous carcinomas. We found KRAS2 gene mutations at codon 12 in all eight cases. All the cases showed loss of p16 protein. In three of these cases the loss was attributed to an exon 2 homozygous deletion in the p16/CDKN2a gene. The majority of the cases had loss of Dpc4 protein and strong nuclear p53 positivity, similar to the molecular signature found in pancreatic ductal adenocarcinoma. We found that E-cadherin was either lost or reduced in all cases and that epidermal growth factor receptor was overexpressed in all cases. The squamous component was positive for p63 staining and thus p63 labeling was helpful in identifying squamous differentiation in adenosquamous carcinomas with an acantholytic growth pattern. In summary, although pancreatic adenosquamous carcinoma and ductal adenocarcinoma have overlapping pathologic and molecular characteristics, there are distinct differences that may be helpful in diagnostic and therapeutic strategies.

    Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc 2009;22;5;651-9

  • Craniosynostosis in patients with Noonan syndrome caused by germline KRAS mutations.

    Kratz CP, Zampino G, Kriek M, Kant SG, Leoni C, Pantaleoni F, Oudesluys-Murphy AM, Di Rocco C, Kloska SP, Tartaglia M and Zenker M

    Department of Pediatrics, University of Freiburg, Freiburg, Germany.

    Craniosynostosis, the premature fusion of one or more cranial sutures, is a developmental defect that disrupts the cranial morphogenetic program, leading to variable dysmorphic craniofacial features and associated functional abnormalities. Craniosynostosis is frequently observed as an associated feature in a number of clinically and genetically heterogeneous syndromic conditions, including a group of disorders caused by activating mutations in genes coding for the fibroblast growth factor receptor family members FGFR1, FGFR2, and FGFR3. In these disorders, dysregulation of intracellular signaling promoted by the aberrant FGFR function is mediated, at least in part, by the RAS-MAPK transduction pathway. Mutations in KRAS, HRAS, and other genes coding for proteins participating in this signaling cascade have recently been identified as underlying Noonan syndrome (NS) and related disorders. While cardinal features of these syndromes include distinctive dysmorphic facial features, reduced growth, congenital heart defects, and variable ectodermal anomalies and cognitive impairment, craniosynostosis is not a recognized feature. Here, we report on the occurrence of premature closure of cranial sutures in subjects with NS, and their specific association with mutations in the KRAS gene. These findings highlight the pathogenetic significance of aberrant signaling mediated by the RAS signaling pathway in other known forms of craniosynostosis, and suggest that, even in the absence of radiologically demonstrable synostosis of the calvarian sutures, dysregulated growth and/or suture closure at specific craniofacial sites might contribute to the craniofacial anomalies occurring in NS.

    Funded by: Telethon: GGP07115

    American journal of medical genetics. Part A 2009;149A;5;1036-40

  • Different types of K-Ras mutations are conversely associated with overall survival in patients with colorectal cancer.

    Winder T, Mündlein A, Rhomberg S, Dirschmid K, Hartmann BL, Knauer M, Drexel H, Wenzl E, De Vries A and Lang A

    Department of Medicine, Academic Teaching Hospital Feldkirch, A-6807 Feldkirch, Austria. thomas.winder@lkhf.at

    A glycine to valine substitution at codon 12 (G12V) in Kirsten-Ras (K-Ras) gene has been associated with reduced overall survival in colorectal cancer patients; however, the effect of other K-Ras mutations than G12V still remains unclear. Therefore, we investigated the role of different K-Ras mutations on overall survival in a homogeneous, large patient cohort with standardized therapy and uniform analysis of K-Ras mutation status. The study included 342 patients with histopathologically proven colorectal cancer. Survival data were provided by the federal agency for statistics in Austria. Occurrence of K-Ras mutations at codons 12, 13 and 61 were determined by capillary sequencing. The overall K-Ras mutation frequency in carcinoma tissue was 28%. Carriers of the G12V mutation at the K-Ras gene showed a significantly decreased overall survival compared to carriers of the wild-type [HR=2.56 (1.15-5.69)]. Other mutations than G12V were associated with better overall survival compared to wild-type [HR=0.44 (0.2-0.99)]. In conclusion, for the first time, our study showed clearly that different types of K-Ras mutations are conversely associated with overall survival in patients with colorectal cancer.

    Oncology reports 2009;21;5;1283-7

  • Micropapillary lung adenocarcinoma: EGFR, K-ras, and BRAF mutational profile.

    De Oliveira Duarte Achcar R, Nikiforova MN and Yousem SA

    Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA 15213-2582, USA.

    Micropapillary lung adenocarcinoma (MPA) has been reported as an aggressive variant of adenocarcinoma, frequently manifesting at high stage with a poor prognosis. We analyzed the clinical and molecular profile of 15 primary MPAs for K-ras, EGFR, and BRAF mutations and performed fluorescence in situ hybridization for EGFR amplification. In our study, 11 (73%) of 15 MPAs harbored mutually exclusive mutations: 5 (33%) K-ras, 3 (20%) EGFR, and 3 (20%) BRAF. Mutations in all 3 genes occurred in patients with a smoking history and tumors with mucinous differentiation and secondary lepidic, acinar, and solid growth, suggesting that in a Western population, cytomorphologic correlation with genetic mutations is more unpredictable than in Japanese cohorts. We conclude that K-ras, EGFR, and BRAF mutations are disproportionately seen in adenocarcinomas of lung with a dominant micropapillary growth pattern compared with conventional adenocarcinoma in our institutional experience.

    American journal of clinical pathology 2009;131;5;694-700

  • Protein hnRNP A1 and its derivative Up1 unfold quadruplex DNA in the human KRAS promoter: implications for transcription.

    Paramasivam M, Membrino A, Cogoi S, Fukuda H, Nakagama H and Xodo LE

    Department of Biomedical Science and Technology, School of Medicine, Udine, Italy.

    The promoter of the human KRAS proto-oncogene contains a structurally polymorphic nuclease hypersensitive element (NHE) whose purine strand forms a parallel G-quadruplex structure (called 32R). In a previous work we reported that quadruplex 32R is recognized by three nuclear proteins: PARP-1, Ku70 and hnRNP A1. In this study we describe the interaction of recombinant hnRNP A1 (A1) and its derivative Up1 with the KRAS G-quadruplex. Mobility-shift experiments show that A1/Up1 binds specifically, and also with a high affinity, to quadruplex 32R, while CD demonstrates that the proteins strongly reduce the intensity of the 260 nm-ellipticity-the hallmark for parallel G4-DNA-and unfold the G-quadruplex. Fluorescence resonance energy transfer melting experiments reveal that A1/Up1 completely abrogates the cooperative quadruplex-to-ssDNA transition that characterizes the KRAS quadruplex and facilitates the association between quadruplex 32R and its complementary polypyrimidine strand. When quadruplex 32R is stabilized by TMPyP4, A1/Up1 brings about only a partial destabilization of the G4-DNA structure. The possible role played by hnRNP A1 in the mechanism of KRAS transcription is discussed.

    Nucleic acids research 2009;37;9;2841-53

  • Mutational analysis of KRAS, BRAF, and TP53 genes of ovarian serous carcinomas in Korean women.

    Cho YH, Kim DY, Kim JH, Kim YM, Kim KR, Nam JH and Kim YT

    Department of Obstetrics and Gynecology, College of Medicine, University of Ulsan, Asan Medical Center, Songpa-Gu, Seoul, Korea.

    Purpose: To assess the prevalence of KRAS, BRAF, and TP53 mutations in cases of low-grade and high-grade serous carcinomas and to evaluate the clinical outcomes of these morphologically distinct carcinomas.

    Patients with primary invasive serous carcinomas were classified according to the universal grading system. Grade 2 serous tumors were excluded. A total of 100 patients were included for clinical evaluation. Thirty-seven patients, including 20 with low-grade and 17 with high-grade carcinomas, were selected for mutational analysis.

    Results: The low-grade carcinoma group was characterized by young age and premenopausal period compared with the high-grade carcinoma group, but there were no statistically significant differences in stage, metastasis of lymph node and residual disease. There were no statistically significant differences in survival rates, however, the low-grade carcinoma group showed a trend for improved progression-free survival compared with the high-grade carcinoma group of early stage (p = 0.064). Mutations in KRAS and BRAF were found in 6 (30%) and 2 (10%) patients in the low-grade carcinoma group, respectively, however, they were not found in the high-grade carcinoma group. KRAS and BRAF mutations were mutually exclusive, and both mutations were observed in 40% (8/20). The frequency of TP53 mutations in low-grade and high-grade carcinoma groups were found in 20% (4/20) and 70.6% (12/17), respectively (p = 0.009).

    Conclusion: Low-grade serous carcinoma shows mutation pattern different from that with high-grade carcinoma. As there were no significant differences in stage distribution and survival, especially in advanced stage, we suggest that more studies are needed to segregate these patients into distinct disease entities.

    Yonsei medical journal 2009;50;2;266-72

  • TP53 mutations predict disease control in metastatic colorectal cancer treated with cetuximab-based chemotherapy.

    Oden-Gangloff A, Di Fiore F, Bibeau F, Lamy A, Bougeard G, Charbonnier F, Blanchard F, Tougeron D, Ychou M, Boissière F, Le Pessot F, Sabourin JC, Tuech JJ, Michel P and Frebourg T

    Inserm U614, Faculty of Medicine, Institute for Biomedical Research, University of Rouen, Rouen, France.

    Recent studies have suggested that activation of the EGFR pathway leads to malignant transformation only if the p53 protein is inactivated. Therefore, we evaluated the impact of TP53 mutations on cetuximab-based chemotherapy (CT) sensitivity in combination with KRAS mutations that have been associated with cetuximab resistance. KRAS and TP53 status were assessed in tumours from 64 metastatic colorectal cancer patients treated with cetuximab-based CT and correlated to clinical response using the Fisher's exact test. Times to progression (TTPs) according to gene status were calculated using the Kaplan-Meier method and compared with log-rank test. TP53 mutations were found in 41 patients and were significantly associated with controlled disease (CD), as defined as complete response, partial response or stable disease (P=0.037) and higher TTP (20 vs 12 weeks, P=0.004). Remarkably, in the subgroup of 46 patients without KRAS mutation, but not in patients with KRAS mutation, TP53 mutations were also associated with CD (P=0.008) and higher TTP (24 vs 12 weeks, P=0.0007). This study suggests that TP53 mutations are predictive of cetuximab sensitivity, particularly in patients without KRAS mutation, and that TP53 genotyping could have a clinical interest to select patients who should benefit from cetuximab-based CT.

    British journal of cancer 2009;100;8;1330-5

  • Genetic mutations associated with cigarette smoking in pancreatic cancer.

    Blackford A, Parmigiani G, Kensler TW, Wolfgang C, Jones S, Zhang X, Parsons DW, Lin JC, Leary RJ, Eshleman JR, Goggins M, Jaffee EM, Iacobuzio-Donahue CA, Maitra A, Klein A, Cameron JL, Olino K, Schulick R, Winter J, Vogelstein B, Velculescu VE, Kinzler KW and Hruban RH

    Department of Oncology, The Sol Goldman Pancreatic Cancer Research Center, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21231, USA.

    Cigarette smoking doubles the risk of pancreatic cancer, and smoking accounts for 20% to 25% of pancreatic cancers. The recent sequencing of the pancreatic cancer genome provides an unprecedented opportunity to identify mutational patterns associated with smoking. We previously sequenced >750 million bp DNA from 23,219 transcripts in 24 adenocarcinomas of the pancreas (discovery screen). In this previous study, the 39 genes that were mutated more than once in the discovery screen were sequenced in an additional 90 adenocarcinomas of the pancreas (validation screen). Here, we compared the somatic mutations in the cancers obtained from individuals who ever smoked cigarettes (n = 64) to the somatic mutations in the cancers obtained from individuals who never smoked cigarettes (n = 50). When adjusted for age and gender, analyses of the discovery screen revealed significantly more nonsynonymous mutations in the carcinomas obtained from ever smokers (mean, 53.1 mutations per tumor; SD, 27.9) than in the carcinomas obtained from never smokers (mean, 38.5; SD, 11.1; P = 0.04). The difference between smokers and nonsmokers was not driven by mutations in known driver genes in pancreatic cancer (KRAS, TP53, CDKN2A/p16, and SMAD4), but instead was predominantly observed in genes mutated at lower frequency. No differences were observed in mutations in carcinomas from the head versus tail of the gland. Pancreatic carcinomas from cigarette smokers harbor more mutations than do carcinomas from never smokers. The types and patterns of these mutations provide insight into the mechanisms by which cigarette smoking causes pancreatic cancer.

    Funded by: NCI NIH HHS: CA62924, P50 CA062924, P50 CA062924-08S30011, P50 CA062924-090011, P50 CA062924-160011, R01 CA039416, R37 CA043460

    Cancer research 2009;69;8;3681-8

  • KRAS mutations in non-small cell lung cancer.

    Riely GJ, Marks J and Pao W

    Thoracic Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.

    Some non-small cell lung cancers (NSCLCs) harbor a single specific mutated oncogene that is thought to be the primary genetic "driver" leading to cancer. The two most commonly mutated oncogenes in lung cancer encode for the epidermal growth factor receptor (EGFR) and KRAS. EGFR kinase domain mutations were only recently identified, but they have already been established in the clinic as valid predictors of increased sensitivity to EGFR kinase inhibitors (gefitinib and erlotinib). By contrast, even though KRAS mutations were identified in NSCLC tumors more than 20 years ago, we have only just begun to appreciate the clinical value of KRAS tumor status. Recent studies indicate that patients with mutant KRAS tumors fail to benefit from adjuvant chemotherapy, and their disease does not respond to EGFR inhibitors. There is a dire need for therapies specifically for patients with KRAS mutant NSCLC. In this review, we summarize the initial discovery of RAS mutations in NSCLC, describe work exploring associations with clinical factors and outcomes, and provide an overview of current approaches to targeting KRAS mutant NSCLC.

    Proceedings of the American Thoracic Society 2009;6;2;201-5

  • DPC4 gene status of the primary carcinoma correlates with patterns of failure in patients with pancreatic cancer.

    Iacobuzio-Donahue CA, Fu B, Yachida S, Luo M, Abe H, Henderson CM, Vilardell F, Wang Z, Keller JW, Banerjee P, Herman JM, Cameron JL, Yeo CJ, Halushka MK, Eshleman JR, Raben M, Klein AP, Hruban RH, Hidalgo M and Laheru D

    Department of Pathology, Surgery, and Oncology, The Sol Goldman Pancreatic Cancer Research Center, Johns Hopkins Medical Institutions, Baltimore, MD 21231, USA. ciacobu@jhmi.edu

    Purpose: Contrary to the extensive data accumulated regarding pancreatic carcinogenesis, the clinical and molecular features characteristic of advanced stage (stage III and IV) disease are unknown. A comprehensive study of pancreatic cancers from patients who have succumbed to their disease has the potential to greatly expand our understanding of the most lethal stage of this disease and identify novel areas for intervention.

    Rapid autopsies were performed on 76 patients with documented pancreatic cancer. The histologic features of end stage disease were determined and correlated to the stage at initial diagnosis, patterns of failure (locally destructive v metastatic disease) and the status of the KRAS2, TP53, and DPC4 genes.

    Results: At autopsy, 30% of patients died with locally destructive pancreatic cancer, and 70% died with widespread metastatic disease. These divergent patterns of failure found at autopsy (locally destructive v metastatic) were unrelated to clinical stage at initial presentation, treatment history, or histopathologic features. However, Dpc4 immunolabeling status of carcinoma tissues harvested at autopsy, a sensitive marker of DPC4 genetic status, was highly correlated with the presence of widespread metastasis but not with locally destructive tumors (P = .007).

    Conclusion: Pancreatic cancers are represented by distinct genetic subtypes with significantly different patterns of failure. Determinations of DPC4 status at initial diagnosis may be of value in stratifying patients into treatment regimens related to local control versus systemic therapy.

    Funded by: NCI NIH HHS: CA106610, CA62924

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2009;27;11;1806-13

  • Cetuximab and chemotherapy as initial treatment for metastatic colorectal cancer.

    Van Cutsem E, Köhne CH, Hitre E, Zaluski J, Chang Chien CR, Makhson A, D'Haens G, Pintér T, Lim R, Bodoky G, Roh JK, Folprecht G, Ruff P, Stroh C, Tejpar S, Schlichting M, Nippgen J and Rougier P

    University Hospital Gasthuisberg, Digestive Oncology Unit, Herestraat 49, 3000 Leuven, Belgium. eric.vancutsem@uz.kuleuven.ac.be

    Background: We investigated the efficacy of cetuximab plus irinotecan, fluorouracil, and leucovorin (FOLFIRI) as first-line treatment for metastatic colorectal cancer and sought associations between the mutation status of the KRAS gene in tumors and clinical response to cetuximab.

    Methods: We randomly assigned patients with epidermal growth factor receptor-positive colorectal cancer with unresectable metastases to receive FOLFIRI either alone or in combination with cetuximab. The primary end point was progression-free survival.

    Results: A total of 599 patients received cetuximab plus FOLFIRI, and 599 received FOLFIRI alone. The hazard ratio for progression-free survival in the cetuximab-FOLFIRI group as compared with the FOLFIRI group was 0.85 (95% confidence interval [CI], 0.72 to 0.99; P=0.048). There was no significant difference in the overall survival between the two treatment groups (hazard ratio, 0.93; 95% CI, 0.81 to 1.07; P=0.31). There was a significant interaction between treatment group and KRAS mutation status for tumor response (P=0.03) but not for progression-free survival (P=0.07) or overall survival (P=0.44). The hazard ratio for progression-free survival among patients with wild-type-KRAS tumors was 0.68 (95% CI, 0.50 to 0.94), in favor of the cetuximab-FOLFIRI group. The following grade 3 or 4 adverse events were more frequent with cetuximab plus FOLFIRI than with FOLFIRI alone: skin reactions (which were grade 3 only) (in 19.7% vs. 0.2% of patients, P<0.001), infusion-related reactions (in 2.5% vs. 0%, P<0.001), and diarrhea (in 15.7% vs. 10.5%, P=0.008).

    Conclusions: First-line treatment with cetuximab plus FOLFIRI, as compared with FOLFIRI alone, reduced the risk of progression of metastatic colorectal cancer. The benefit of cetuximab was limited to patients with KRAS wild-type tumors. (ClinicalTrials.gov number, NCT00154102.)

    The New England journal of medicine 2009;360;14;1408-17

  • EGFR and K-ras mutations along the spectrum of pulmonary epithelial tumors of the lung and elaboration of a combined clinicopathologic and molecular scoring system to predict clinical responsiveness to EGFR inhibitors.

    Sartori G, Cavazza A, Sgambato A, Marchioni A, Barbieri F, Longo L, Bavieri M, Murer B, Meschiari E, Tamberi S, Cadioli A, Luppi F, Migaldi M and Rossi G

    Section of Pathologic Anatomy, Azienda Ospedaliero-Universitaria Policlinico di Modena, Via del Pozzo, 71- 41100- Modena, Italy.

    We tested 418 neoplasms along the whole spectrum of primary lung tumor histotypes for epidermal growth factor receptor (EGFR) and K-ras mutations. Clinicopathologic data from 154 patients undergoing treatment with EGFR tyrosine kinase inhibitors (TKIs) were retrospectively studied. A scoring system assigning a score for each positive or negative characteristic (+1, female sex, nonsmoking status, adenocarcinoma histotype, Asian ethnicity, and EGFR mutation; -1, current smoker and K-ras mutation; and 0, male sex, ex-smoker, nonadenocarcinoma histotype, and no mutations) was elaborated and tested with EGFR-TKI response. Salivary gland-type, mucin-rich, and neuroendocrine tumors do not harbor EGFR mutations. A subset of nonmucinous adenocarcinomas, not necessarily of the bronchioloalveolar type, is related to EGFR mutations. Three probability groups significantly correlating with response to EGFR-TKIs were identified. Of note, the addition of molecular results did not significantly change the predictive value obtained by the combination of clinicopathologic characteristics alone in this scoring system. K-ras mutations, significantly associated with the mucin-secreting type of adenocarcinoma, consistently predict lack of response in white patients.

    American journal of clinical pathology 2009;131;4;478-89

  • EML4-ALK lung cancers are characterized by rare other mutations, a TTF-1 cell lineage, an acinar histology, and young onset.

    Inamura K, Takeuchi K, Togashi Y, Hatano S, Ninomiya H, Motoi N, Mun MY, Sakao Y, Okumura S, Nakagawa K, Soda M, Choi YL, Mano H and Ishikawa Y

    Division of Pathology, The Cancer Institute, Japanese Foundation for Cancer Research, Koto-ku, Tokyo, Japan.

    A subset of lung cancers harbors a small inversion within chromosome 2p, giving rise to a transforming fusion gene, EML4-ALK (echinoderm microtubule-associated protein-like 4 gene and the anaplastic lymphoma kinase gene), which encodes an activated tyrosine kinase. We have earlier examined the presence of EML4-ALK by multiplex reverse transcription-polymerase chain reaction in 363 specimens of lung cancer, identifying 11 adenocarcinoma cases featuring the fusion gene. In this study, we clinicopathologically examined the characteristics of the EML4-ALK-positive cases, including the mutation status of EGFR, KRAS, and TP53, and whether they were of thyroid transcription factor-1 (TTF-1) cell lineage or not. Of 11 patients, 4 (36%) with EML4-ALK-positive lung adenocarcinomas who were below 50 years of age were affected by these diseases, as compared with 12 of 242 patients (5.0%) with EML4-ALK-negative lung adenocarcinomas (P=0.00038). EML4-ALK-positive lung adenocarcinomas were characterized by less-differentiated grade (P=0.0082) and acinar-predominant structure (P<0.0001) in histology. Furthermore, the presence of EML4-ALK appears to be mutually exclusive for EGFR and KRAS mutations (P=0.00018), whereas coexisting with TP53 mutations at a low frequency (1/11=9.1%), and correlating with non- or light smoking (P=0.040), in line with the TTF-1 immunoreactivity. Thus, EML4-ALK-positive tumors may form a distinct entity among lung adenocarcinomas, characterized by young onset, acinar histology, no or rare mutations in EGFR, KRAS, and TP53, and a TTF-1 cell lineage, all in agreement with the prevalence in non- or light smokers.

    Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc 2009;22;4;508-15

  • Germline and somatic NF1 mutations in sporadic and NF1-associated malignant peripheral nerve sheath tumours.

    Bottillo I, Ahlquist T, Brekke H, Danielsen SA, van den Berg E, Mertens F, Lothe RA and Dallapiccola B

    IRCCS-CSS, San Giovanni Rotondo and CSS-Mendel Institute, 00198 Rome, Italy.

    Malignant peripheral nerve sheath tumours (MPNSTs) are a malignancy occurring with increased frequency in patients with neurofibromatosis type 1 (NF1). In contrast to the well-known spectrum of germline NF1 mutations, the information on somatic mutations in MPNSTs is limited. In this study, we screened NF1, KRAS, and BRAF in 47 MPNSTs from patients with (n = 25) and without (n = 22) NF1. In addition, DNA from peripheral blood and cutaneous neurofibroma biopsies from, respectively, 14/25 and 7/25 of the NF1 patients were analysed. Germline NF1 mutations were detected in ten NF1 patients, including three frameshift, three nonsense, one missense, one splicing alteration, and two large deletions. Somatic NF1 mutations were found in 10/25 (40%) NF1-associated MPNSTs, in 3/7 (43%) neurofibromas, and in 9/22 (41%) sporadic MPNSTs. Large genomic copy number changes accounted for 6/10 and 7/13 somatic mutations in NF1-associated and sporadic MPNSTs, respectively. Two NF1-associated and 13 sporadic MPNSTs did not show any NF1 mutation. A major role of the KRAS and BRAF genes was ruled out. The spectrum of germline NF1 mutations in neurofibromatosis patients with MPNST is different from the spectrum of somatic mutations seen in MPNSTs. However, the somatic events share common characteristics with the NF1-related and the sporadic tumours.

    The Journal of pathology 2009;217;5;693-701

  • Germline BRAF mutations in Noonan, LEOPARD, and cardiofaciocutaneous syndromes: molecular diversity and associated phenotypic spectrum.

    Sarkozy A, Carta C, Moretti S, Zampino G, Digilio MC, Pantaleoni F, Scioletti AP, Esposito G, Cordeddu V, Lepri F, Petrangeli V, Dentici ML, Mancini GM, Selicorni A, Rossi C, Mazzanti L, Marino B, Ferrero GB, Silengo MC, Memo L, Stanzial F, Faravelli F, Stuppia L, Puxeddu E, Gelb BD, Dallapiccola B and Tartaglia M

    IRCCS, San Giovanni Rotondo, Dipartimento di Medicina Sperimentale e Patologia, Università La Sapienza, Rome, Italy.

    Noonan, LEOPARD, and cardiofaciocutaneous syndromes (NS, LS, and CFCS) are developmental disorders with overlapping features including distinctive facial dysmorphia, reduced growth, cardiac defects, skeletal and ectodermal anomalies, and variable cognitive deficits. Dysregulated RAS-mitogen-activated protein kinase (MAPK) signal traffic has been established to represent the molecular pathogenic cause underlying these conditions. To investigate the phenotypic spectrum and molecular diversity of germline mutations affecting BRAF, which encodes a serine/threonine kinase functioning as a RAS effector frequently mutated in CFCS, subjects with a diagnosis of NS (N=270), LS (N=6), and CFCS (N=33), and no mutation in PTPN11, SOS1, KRAS, RAF1, MEK1, or MEK2, were screened for the entire coding sequence of the gene. Besides the expected high prevalence of mutations observed among CFCS patients (52%), a de novo heterozygous missense change was identified in one subject with LS (17%) and five individuals with NS (1.9%). Mutations mapped to multiple protein domains and largely did not overlap with cancer-associated defects. NS-causing mutations had not been documented in CFCS, suggesting that the phenotypes arising from germline BRAF defects might be allele specific. Selected mutant BRAF proteins promoted variable gain of function of the kinase, but appeared less activating compared to the recurrent cancer-associated p.Val600Glu mutant. Our findings provide evidence for a wide phenotypic diversity associated with mutations affecting BRAF, and occurrence of a clinical continuum associated with these molecular lesions.

    Funded by: NHLBI NIH HHS: HL074728, HL71207, P50 HL074728, R01 HL071207, R01 HL071207-07; NICHD NIH HHS: HD01294, K24 HD001294; Telethon: GGP07115

    Human mutation 2009;30;4;695-702

  • PKCdelta survival signaling in cells containing an activated p21Ras protein requires PDK1.

    Xia S, Chen Z, Forman LW and Faller DV

    Cancer Research Center, Boston University School of Medicine, Boston, Massachusetts 02118, USA.

    Protein kinase C delta (PKCdelta) modulates cell survival and apoptosis in diverse cellular systems. We recently reported that PKCdelta functions as a critical anti-apoptotic signal transducer in cells containing activated p21(Ras) and results in the activation of AKT, thereby promoting cell survival. How PKCdelta is regulated by p21(Ras), however, remains incompletely understood. In this study, we show that PKCdelta, as a transducer of anti-apoptotic signals, is activated by phosphotidylinositol 3' kinase/phosphoinositide-dependent kinase 1 (PI(3)K-PDK1) to deliver the survival signal to Akt in the environment of activated p21(Ras). PDK1 is upregulated in cells containing an activated p21Ras. Knock-down of PDK1, PKCdelta, or AKT forces cells containing activated p21(Ras) to undergo apoptosis. PDK1 regulates PKCdelta activity, and constitutive expression of PDK1 increases PKCdelta activity in different cell types. Conversely, expression of a kinase-dead (dominant-negative) PDK1 significantly suppresses PKCdelta activity. p21(Ras)-mediated survival signaling is therefore regulated by via a PI(3)K-AKT pathway, which is dependent upon both PDK1 and PKCdelta, and PDK1 activates and regulates PKCdelta to determine the fate of cells containing a mutated, activated p21(Ras).

    Funded by: NCI NIH HHS: CA108100, CA112102, R01 CA112102, R01 CA112102-01A1, R01 CA112102-02, R01 CA112102-03, R01 CA112102-03S1, R01 CA112102-04, R01 CA112102-04S1, R41 CA108100, R41 CA108100-01

    Cellular signalling 2009;21;4;502-8

  • Results of a phase I trial of 12 patients with locally advanced pancreatic carcinoma combining gefitinib, paclitaxel, and 3-dimensional conformal radiation: report of toxicity and evaluation of circulating K-ras as a potential biomarker of response to therapy.

    Olsen CC, Schefter TE, Chen H, Kane M, Leong S, McCarter MD, Chen Y, Mack P, Eckhardt SG, Stiegmann G and Raben D

    Department of Radiation Oncology, University of Colorado Denver Health Sciences Center, Aurora, CO, USA.

    Objective: To evaluate the toxicity of daily gefitinib, an epidermal growth factor receptor-tyrosine kinase inhibitor, with concurrent chemoradiation (CRT) in patients with locally advanced pancreatic adenocarcinoma and prospectively evaluate plasma k-ras as a potential marker of response to gefitinib and CRT.

    Methods: Eleven of 12 eligible patients enrolled received a 7-day induction of gefitinib (250 mg PO) followed by daily gefitinib with concurrent CRT. Patients received 50.4 Gy/28 fractions of external beam radiation with weekly paclitaxel (40 mg/m IV) followed by maintenance on gefitinib. Plasma k-ras codon 12 mutations were detected using a two-stage restriction fragment length polymorphism-polymerase chain reaction assay on patients' plasma both before and after therapy. Mutations were confirmed by direct sequencing.

    Results: Common adverse events included grade 1 skin rash (63%), grade 1 to 2 gastrointestinal symptoms including anorexia, nausea, vomiting, and diarrhea occurred in 63% of patients, grade 3 nausea occurred in 45% of patients. Three patients did not complete therapy, only one was possibly associated with study drug. K-ras mutations were detected in the pre-gefitinib plasma of 5/11 patients and in the matched tumor tissue of 3/4 patients. In patients where k-ras mutations were undetectable post-treatment, survival times were favorable.

    Conclusions: Combination of daily gefitinib with concurrent CRT in this locally advanced pancreatic cancer population was reasonably tolerated. Rapid changes in serum k-ras may provide critical information as to the efficacy of a novel agent and assist in tailoring treatment for cancers of the pancreas.

    American journal of clinical oncology 2009;32;2;115-21

  • Tagging single-nucleotide polymorphisms in candidate oncogenes and susceptibility to ovarian cancer.

    Quaye L, Song H, Ramus SJ, Gentry-Maharaj A, Høgdall E, DiCioccio RA, McGuire V, Wu AH, Van Den Berg DJ, Pike MC, Wozniak E, Doherty JA, Rossing MA, Ness RB, Moysich KB, Høgdall C, Blaakaer J, Ovarian Cancer Association Consortium, Easton DF, Ponder BA, Jacobs IJ, Menon U, Whittemore AS, Krüger-Kjaer S, Pearce CL, Pharoah PD and Gayther SA

    Gynaecological Oncology Department, UCL EGA Institute for Women's Health, University College London, London, UK.

    Low-moderate risk alleles that are relatively common in the population may explain a significant proportion of the excess familial risk of ovarian cancer (OC) not attributed to highly penetrant genes. In this study, we evaluated the risks of OC associated with common germline variants in five oncogenes (BRAF, ERBB2, KRAS, NMI and PIK3CA) known to be involved in OC development. Thirty-four tagging SNPs in these genes were genotyped in approximately 1800 invasive OC cases and 3000 controls from population-based studies in Denmark, the United Kingdom and the United States. We found no evidence of disease association for SNPs in BRAF, KRAS, ERBB2 and PIK3CA when OC was considered as a single disease phenotype; but after stratification by histological subtype, we found borderline evidence of association for SNPs in KRAS and BRAF with mucinous OC and in ERBB2 and PIK3CA with endometrioid OC. For NMI, we identified a SNP (rs11683487) that was associated with a decreased risk of OC (unadjusted P(dominant)=0.004). We then genotyped rs11683487 in another 1097 cases and 1792 controls from an additional three case-control studies from the United States. The combined odds ratio was 0.89 (95% confidence interval (CI): 0.80-0.99) and remained statistically significant (P(dominant)=0.032). We also identified two haplotypes in ERBB2 associated with an increased OC risk (P(global)=0.034) and a haplotype in BRAF that had a protective effect (P(global)=0.005). In conclusion, these data provide borderline evidence of association for common allelic variation in the NMI with risk of epithelial OC.

    Funded by: Cancer Research UK: C8804/A7058; NCI NIH HHS: CA16056, CA17054, CA61132, CA63464, CA71766, K07-CA80668, N01-PC-67010, R01 CA87538, R01CA095023, R03-CA113148

    British journal of cancer 2009;100;6;993-1001

  • PIK3CA mutation is associated with poor prognosis among patients with curatively resected colon cancer.

    Ogino S, Nosho K, Kirkner GJ, Shima K, Irahara N, Kure S, Chan AT, Engelman JA, Kraft P, Cantley LC, Giovannucci EL and Fuchs CS

    Department of Medical Oncology, Dana-Farber Cancer Institute, Brigham and Women's Hospital, Harvard Medical School, 44 Binney St, Room JF-215C, Boston, MA 02115 USA. shuji_ogino@dfci.harvard.edu

    Purpose: PIK3CA mutation and subsequent activation of the AKT pathway play an important role in colorectal carcinogenesis. However, little is known about the prognostic role of PIK3CA mutation in colon cancer.

    Using 450 resectable colon cancers (stage I to III) in two independent prospective cohorts, we detected PIK3CA mutation in 82 tumors (18%) by pyrosequencing. Cox proportional hazards models were used to calculate hazard ratios (HRs) of colon cancer-specific and overall mortalities, adjusted for patient characteristics and tumoral molecular features, including the CpG island methylation phenotype, microsatellite instability (MSI), LINE-1 hypomethylation, and p53, CIMP, KRAS and BRAF mutation.

    Results: Compared with patients with PIK3CA wild-type tumors, those with PIK3CA-mutated tumors experienced an increase in colon cancer-specific mortality according to univariate analysis (HR = 1.64; 95% CI, 0.95 to 2.86), which persisted after adjusting for other known or potential risk factors for cancer recurrence (including MSI; multivariate HR = 2.23; 95% CI, 1.21 to 4.11). The effect of PIK3CA mutation on cancer survival seemed to differ according to KRAS mutational status. Among patients with KRAS wild-type tumors, the presence of PIK3CA mutation was associated with a significant increase in colon cancer-specific mortality (HR = 3.80; 95% CI, 1.56 to 9.27). In contrast, PIK3CA mutation conferred no significant effect on mortality among patients with KRAS-mutated tumors (HR = 1.25; 95% CI, 0.52 to 2.96).

    Conclusion: Among patients who undergo a curative resection of colon cancer, PIK3CA mutation is associated with shorter cancer-specific survival. The adverse effect of PIK3CA mutation may be potentially limited to patients with KRAS wild-type tumors.

    Funded by: NCI NIH HHS: K07 CA122826, K07 CA122826-02, K08 CA120060-04, P01 CA055075-14, P01 CA087969-09, P01 CA55075, P01 CA87969, P50 CA127003, P50 CA127003-02, R01 CA137178; NIGMS NIH HHS: R01 GM041890-24

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2009;27;9;1477-84

  • Role of miR-143 targeting KRAS in colorectal tumorigenesis.

    Chen X, Guo X, Zhang H, Xiang Y, Chen J, Yin Y, Cai X, Wang K, Wang G, Ba Y, Zhu L, Wang J, Yang R, Zhang Y, Ren Z, Zen K, Zhang J and Zhang CY

    Jiangsu Diabetes Center, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China.

    Dysregulated expression of microRNAs (miRNAs) is associated with a variety of diseases, including colorectal cancer. By comparing more than 200 miRNAs in 13 pairs of matched colorectal cancer and normal adjacent tissue samples through qRT-PCR and microarray analysis, we found a widespread disruption of miRNA expression during colorectal tumorigenesis. In particular, among a panel of presumed targets generated by in silico analysis that may interact with these aberrantly expressed miRNAs, KRAS oncogene has been further experimentally validated as the target of miR-143. First, an inverse correlation between KRAS protein and miR-143 in vivo was found. Second, KRAS expression in Lovo cells was significantly abolished by treatment with miR-143 mimic, whereas miR-143 inhibitor increased KRAS protein level. Third, luciferase reporter assay confirmed that miR-143 directly recognize the 3'-untranslated region of KRAS transcripts. Four, Lovo cells treated with miR-143 inhibitor showed a stimulated cell proliferation, whereas miR-143 overexpression had an opposite effect. Finally, inhibition of KRAS expression by miR-143 inhibits constitutive phosphorylation of ERK1/2. Taken together, the present study provides the first evidences that miR-143 is significant in suppressing colorectal cancer cell growth through inhibition of KRAS translation.

    Oncogene 2009;28;10;1385-92

  • Reduction of serum IGF-I levels in patients affected with Monoclonal Gammopathies of undetermined significance or Multiple Myeloma. Comparison with bFGF, VEGF and K-ras gene mutation.

    Greco C, Vitelli G, Vercillo G, Vona R, Giannarelli D, Sperduti I, Pisani F, Capoluongo E, Petti MC and Ameglio F

    Clinical Pathology Service, Polo Oncologico Regina Elena, Rome, Italy. ayyctg@tin.it

    Background: Serum levels of IGF-I in patients affected with multiple myeloma (MM) have been scarcely studied. The present study is aimed to explore this point comparing 55 healthy subjects, 71 monoclonal gammopaties of uncertain significance (MGUS) and 77 overt MM patients. In the same subjects, basic FGF and VEGF, have been detected. All three mediators were analyzed in function of K-ras mutation and melphalan response. Concerning IGF-I, two representative monitoring examples have also been added.

    Methods: Cytokine determinations were performed by commercially available ELISA kits, while K12-ras mutation was investigated on genomic DNA isolated from bone marrow cell specimens by RFLP-PCR assay.

    Results: Significant reductions of IGF-I levels were observed in MGUS and MM as compared with healthy controls. In addition, MM subjects showed significantly decreased serum IGF-I levels than MGUS. Conversely, increasing levels were observed for bFGF and VEGF, molecules significantly correlated. A multivariate analysis corrected for age and gender confirmed the significant difference only for IGF-I values (P = 0.01). K12-ras mutation was significantly associated with malignancy, response to therapy and with significantly increased serum bFGF levels.

    Conclusion: IGF-I reduction in the transition: Controls-->MGUS-->MM and changes observed over time suggest that IGF-I should be furtherly studied in future clinical trials as a possible monitoring marker for MM.

    Journal of experimental & clinical cancer research : CR 2009;28;35

  • Impact of Fc{gamma}RIIa-Fc{gamma}RIIIa polymorphisms and KRAS mutations on the clinical outcome of patients with metastatic colorectal cancer treated with cetuximab plus irinotecan.

    Bibeau F, Lopez-Crapez E, Di Fiore F, Thezenas S, Ychou M, Blanchard F, Lamy A, Penault-Llorca F, Frébourg T, Michel P, Sabourin JC and Boissière-Michot F

    Département de Pathologie, Centre Régional de Lutte Contre le Cancer Val d'Aurelle-Paul Lamarque, 208 rue des Apothicaires, Parc Euromédecine, 34298 Montpellier Cedex 05 France. fbibeau@valdorel.fnclcc.fr

    Purpose: The antiepidermal growth factor receptor antibody cetuximab shows activity in irinotecan-refractory metastatic colorectal cancer (mCRC), mainly in wild-type KRAS tumors. Cetuximab may also exert antitumor effects through antibody-dependent cell-mediated cytotoxicity (ADCC) in which antibody Fc portion interacts with Fc receptors (FcgammaRs) expressed by immune cells. ADCC is influenced by FcgammaRIIa-H131R and FcgammaRIIIa-V158F polymorphisms that are clinically relevant in follicular lymphoma and metastatic breast cancer treated with rituximab and trastuzumab, respectively. We investigated the association of FcgammaR polymorphisms and KRAS mutation with the outcome of irinotecan-refractory mCRC patients treated with cetuximab plus irinotecan.

    Tumor and normal tissues from 69 patients were screened for KRAS mutations using a sensitive multiplex assay and genotyped for FcgammaRIIa and FcgammaRIIIa polymorphisms by direct sequencing and multiplex allele-specific polymerase chain reaction, respectively. The results were correlated with response and progression-free survival (PFS).

    Results: KRAS mutations were associated with lower response rate (4% v 27% in nonmutated patients; P = .021) and shorter PFS (3.0 v 5.3 months; P = .021). Patients with FcgammaRIIa-131H/H and/or FcgammaIIIa-158V/V genotypes had longer PFS than 131R and 158F carriers (5.5 v 3.0 months; P = .005). The difference remained significant for mutated-KRAS patients. By multivariate analysis, KRAS mutation and FcgammaR combined status were independent risk factors for PFS.

    Conclusion: Combined FcgammaRIIa/FcgammaRIIIa polymorphisms are prognostic factors for disease progression in mCRC patients treated with cetuximab plus irinotecan. As these polymorphisms are also clinically relevant in mutated-KRAS mCRC, an important role of ADCC in cetuximab efficacy is presumed.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2009;27;7;1122-9

  • KRAS mutations and sensitivity to epidermal growth factor receptor inhibitors in colorectal cancer: practical application of patient selection.

    Jimeno A, Messersmith WA, Hirsch FR, Franklin WA and Eckhardt SG

    Medical Oncology Division, PO Box 6511, MS 8117, Aurora, CO, 80045, USA. Antonio.Jimeno@UCDenver.edu

    Recent retrospective evidence from several randomized studies has established that advanced colorectal cancer patients with tumors harboring a mutation in the KRAS gene do not derive benefit from the administration of epidermal growth factor receptor-directed monoclonal antibodies, such as cetuximab or panitumumab. This represents a paradigm-changing event and will have substantial impact on current and future anticancer drug development. These results add to the economic and ethical considerations involved in the development of novel targeted therapies and should increase our scrutiny of mechanisms of resistance and predictive biomarkers while in earlier developmental stages. In this article we will review the available clinical data, discuss the potential implications for future drug development in colorectal cancer, and provide a comprehensive overview of the technical aspects of KRAS mutation testing. In particular we aimed at enumerating the available procedures for mutation detection and their main characteristics, as well as comparing them from a clinical feasibility standpoint. While the true specificity and sensitivity of these methods have yet to be fully characterized, a better understanding of the differences between tests will be critical so that clinicians and pathologists can fully integrate this testing into the routine care of patients with colorectal cancer.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2009;27;7;1130-6

  • Correlation of clinical features with the mutational status of GM-CSF signaling pathway-related genes in juvenile myelomonocytic leukemia.

    Yoshida N, Yagasaki H, Xu Y, Matsuda K, Yoshimi A, Takahashi Y, Hama A, Nishio N, Muramatsu H, Watanabe N, Matsumoto K, Kato K, Ueyama J, Inada H, Goto H, Yabe M, Kudo K, Mimaya J, Kikuchi A, Manabe A, Koike K and Kojima S

    Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.

    Mutations in RAS, neurofibromatosis type 1 (NF1), and PTPN11, constituents of the granulocyte-macrophage colony-stimulating factor signaling pathway, have been recognized in patients with juvenile myelomonocytic leukemia (JMML). We assessed 71 children with JMML for NRAS, KRAS, and PTPN11 mutations and evaluated their clinical significance. Of the 71 patients, three had been clinically diagnosed with neurofibromatosis type 1, and PTPN11 and NRAS/KRAS mutations were found in 32 (45%) and 13 (18%) patients, respectively. No simultaneous aberrations were found. Compared with patients with RAS mutation or without any aberrations, patients with PTPN11 mutation were significantly older at diagnosis and had higher fetal Hb levels, both of which have been recognized as poor prognostic factors. As was expected, overall survival was lower for patients with the PTPN11 mutation than for those without (25 versus 64%; p = 0.0029). In an analysis of 48 patients who received hematopoietic stem cell transplantation, PTPN11 mutations were also associated with poor prognosis for survival. Mutation in PTPN11 was the only unfavorable factor for relapse after hematopoietic stem cell transplantation (p = 0.001). All patients who died after relapse had PTPN11 mutation. These results suggest that JMML with PTPN11 mutation might be a distinct subgroup with specific clinical characteristics and poor outcome.

    Pediatric research 2009;65;3;334-40

  • EGFR and HER2 genomic gain in recurrent non-small cell lung cancer after surgery: impact on outcome to treatment with gefitinib and association with EGFR and KRAS mutations in a Japanese cohort.

    Varella-Garcia M, Mitsudomi T, Yatabe Y, Kosaka T, Nakajima E, Xavier AC, Skokan M, Zeng C, Franklin WA, Bunn PA and Hirsch FR

    University of Colorado Cancer Center, Department of Medicine and Pathology, Aurora, CO 80045, USA.

    Background: Sensitivity to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) and frequency of activation mutations in EGFR is lower in Caucasian than Asian non small-cell lung cancer (NSCLC) patients. Increased EGFR gene copy numbers evaluated by fluorescence in situ hybridization (FISH) has been reported as predictor of clinical benefit from EGFR-TKIs in Caucasian NSCLC patients. This study was carried out to verify whether EGFR FISH had similar performance in Japanese patients.

    Methods: A cohort of 44 Japanese patients with recurrent NSCLC after surgery was treated with gefitinib 250 mg daily. The cohort included 48% females and 52% never-smokers; 73% had prior chemotherapy and 57% had stage III-IV at the time of surgery. Adenocarcinoma was the most common histology (86%). FISH was performed using the EGFR/Chromosome Enumeration Probe 7 and PathVysion DNA probes (Abbott Molecular). Specimens were classified as FISH positive when showing gene amplification or high polysomy (> or = 4 copies of the gene in > or = 40% of tumor cells). Tumor response to gefitinib was assessed by RECIST for 33 patients with measurable diseases.

    Results: Twenty-nine tumors (66%) were EGFR FISH+ and 23 (53%) were HER2 FISH+. Overall response rate was 52%, representing 65% of EGFR FISH+ patients and 29% of EGFR FISH- patients (p = 0.0777). Survival was not impacted by the EGFR FISH (p = 0.9395) or the HER2 FISH (p = 0.0671) status. EGFR FISH+ was significantly associated with HER2 FISH+ (p = 0.015) and presence of EGFR mutation (p = 0.0060). EGFR mutation significantly correlated with response (p < 0.0001) and survival after gefitinib (p = 0.0204). EGFR and HER2 FISH status were not associated with KRAS mutation.

    Conclusion: Frequency of EGFR FISH+ status was higher and its predictive power for TKI sensitivity was lower in this Japanese cohort than in Western NSCLC cohorts. These findings support differences in the mechanisms of EGFR pathway activation in NSCLC between Asian and Caucasian populations. Confirmation of these results in larger cohorts is warranted.

    Funded by: NCI NIH HHS: P50 CA058187

    Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer 2009;4;3;318-25

  • EGFR and KRAS mutations in patients with adenocarcinoma of the lung.

    Jang TW, Oak CH, Chang HK, Suo SJ and Jung MH

    Department of Internal Medicine, Kosin University College of Medicine, Busan, Korea. jangtw@ns.kosinmed.or.kr

    Mutations of the epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma viral oncogene (KRAS) are important in the pathogenesis of lung cancer, and recent reports have revealed racial and geographical differences in mutation expression.

    Methods: This study was conducted to investigate the prevalence of EGFR and KRAS mutations and their correlation with clinical variables in Korean patients with adenocarcinoma of the lung. Formalin-fixed adenocarcinoma specimens from 104 randomly selected patients diagnosed at Kosin University Gospel Hospital from October 1996 to January 2005 were used for the study.

    Results: We found a high prevalence of EGFR mutations and a low prevalence of KRAS mutations. EGFR mutations were present in 24% (25 of 104) of the samples: one mutation in exon 18, 13 in exon 19, one in exon 20, and 10 in exon 21. The presence of an EGFR mutation was not associated with gender, smoking history, histological grade, age, bronchioalveolar components, or cancer stage in patients with adenocarcinoma of the lung.

    Conclusions: Mutations of KRAS were present in 9.6% (9 of 94) of the samples: eight in codon 12 and one in codon 13. EGFR mutations were never found in tumors with KRAS mutations, suggesting a mutually exclusive relationship.

    The Korean journal of internal medicine 2009;24;1;48-54

  • [Frequency and clinicopathological associations of K-ras mutations in Venezuelan patients with colo-rectal cancer].

    Estrada P, Rojas-Atencio A, Zabala W, Borjas L, Soca L, Urdaneta K, Alvarez-Nava F, Cañizales J, Rojas J and Soto M

    Universidad Centro Occidental Lisandro Alvarado, Barquisimeto, Venezuela.

    Mutations in the K-ras oncogene are common in colo-rectal cancer, which affect the biological behaviour and may influence the susceptibility to therapy in these tumors. The objective of this work was to identify the types of K-ras mutations observed in referred patients with colo-rectal cancer and to relate them to their degree of histological differentiation and clinical stage. Histopathological and clinical data were obtained from medical records. DNA was obtained from both, fresh tissue and tumor tissue embedded in paraffin. The K-ras gene was amplified through the polymerase chain reaction (PCR) and the amplified fragments were digested with restriction enzymes. We found mutations in codons 12 and 13 of the K-ras oncogene in 23.33% of patients. Of these, 28.57% were located at codon 12, 57.14% were at codon 13 and 14.29% at both codons. They were more frequent in tumors located in the left hemicolon and, according to their histological type, were more frequent in well differentiated adenocarcinomas (58.70%) and in mucinous (28.57%). The identified mutations were more frequent in advanced stages (C2) of Dukes' classification. The molecular analysis of the K-ras oncogene made mutations evident, which could be useful in the diagnosis and prognosis of colorectal tumors. The frequency of mutations found in this work is similar to some of those reported worldwide; however, they differ in the more frequent type of mutation, which, in our study, was located at codon 13 in more than 50% of the cases.

    Investigación clínica 2009;50;1;55-63

  • KRAS mutations and susceptibility to cetuximab and panitumumab in colorectal cancer.

    Jimeno A, Messersmith WA, Hirsch FR, Franklin WA and Eckhardt SG

    University of Colorado Cancer Center, Denver, CO, USA. Antonio.Jimeno@UCDenver.edu

    Recent retrospective evidence from several randomized studies has established that advanced colorectal cancer patients with tumors harboring a mutation in the KRAS gene do not derive benefit from the administration of epidermal growth factor receptor-directed monoclonal antibodies, such as cetuximab or panitumumab. This represents a paradigm-changing event and will have substantial impact on current and future anticancer drug development. These results add to the economic and ethical considerations involved in the development of novel targeted therapies and should increase our scrutiny of mechanisms of resistance and predictive biomarkers while in earlier developmental stages. In this article, we will review the available clinical data and discuss the implications for future drug development in colorectal cancer.

    Cancer journal (Sudbury, Mass.) 2009;15;2;110-3

  • Microsatellite instability-low colorectal cancer acquires a KRAS mutation during the progression from Dukes' A to Dukes' B.

    Asaka S, Arai Y, Nishimura Y, Yamaguchi K, Ishikubo T, Yatsuoka T, Tanaka Y and Akagi K

    Division of Molecular Diagnosis and Cancer Prevention, , SaitamaCancer Center, Kitaadati-gun, Saitama, Japan.

    The classification of colorectal cancer (CRC) by microsatellite instability (MSI) status is important for effective clinical management. In fact, microsatellite instability-high (MSI-H) cancer has distinctive clinicopathological and molecular features. However, microsatellite instability-low (MSI-L) cancer is not clearly defined. The objective of this study was to further clarify the characteristics of MSI-L CRC. A consecutive series of 940 primary CRCs were subdivided into three groups according to the level of MSI and analyzed the clinicopathological features and genetic changes in the KRAS, BRAF and p53 mutation and the loss of heterozygosity (LOH) of adenomatous polyposis coli (APC) gene and methylation status of the O(6)-methylguanine-DNA methyltransferase (MGMT) and MLH1 promoter. Of the 940 CRCs, 5.9% were MSI-H, 7.1% were MSI-L and 87% were microsatellite stable (MSS). KRAS and BRAF mutations were detected in 39.4 and 4.6% of the CRCs, respectively. The frequency of KRAS mutations in MSI-H, MSI-L and MSS cancer was 30, 48 and 39%, respectively. The proportion of KRAS mutations in MSI-L cancer increased from 16 to 63% accompanying the progression from Dukes' A to Dukes' B. While the LOH of D5S346, which is located near the APC gene, and p53 mutation was observed in 75 and 67% of MSI-L CRC at Dukes' A, respectively. These results indicated that the LOH of APC and p53 mutation has already occurred by the Dukes' A lake 'suppressor pathway' but not the KRAS mutation in MSI-L CRCs. The genes involving MSI-L carcinogenesis are similar to MSS but the timing and frequency of the KRAS mutation is different.

    Carcinogenesis 2009;30;3;494-9

  • NAT2 fast acetylator genotype and MGMT promoter methylation may contribute to gender difference in K-RAS mutation occurrence in Taiwanese colorectal cancer.

    Huang CC, Chien WP, Wong RH, Cheng YW, Chen MC and Lee H

    Colorectal Division, Department of Surgery, Chung Shan Medical University Hospital, Taichung, Taiwan, Republic of China.

    A recent study conducted by our group showed that the NAT2 fast acetylator genotype is associated with an increasing risk for the development of colorectal cancer (CRC), especially for females. We therefore examined whether a higher risk of CRC in females with the NAT2 fast acetylator genotype was associated with the occurrence of K-RAS mutation, and to further verify whether MGMT promoter methylation was linked to the occurrence of K-RAS mutation in patients with the NAT2 fast acetylator genotype. Herein, 151 CRC cases were examined for NAT2 genetic polymorphisms and MGMT promoter methylation by PCR-RFLP and methylation-specific PCR (MSP). The results of this study show that the NAT2 fast acetylator genotype is associated with the occurrence of K-RAS mutation in female cases (OR = 4.820, 95% CI = 1.113-20.873), but not associated with MGMT promoter methylation. Surprisingly, MGMT promoter methylation significantly deepens the impact of NAT2 fast acetylation on K-RAS mutation in the female cases (OR = 5.129, 95% CI = 1.092-24.105). In conclusion, Taiwanese women with the NAT2 fast acetylator genotype may exhibit a higher risk of CRC with increased occurrence of K-RAS mutation. Detection of NAT2 genotypes and MGMT promoter methylation may be useful in the risk assessment for CRC in Taiwanese women.

    Environmental and molecular mutagenesis 2009;50;2;127-33

  • Overexpressed vs mutated Kras in murine fibroblasts: a molecular phenotyping study.

    Horsch M, Recktenwald CV, Schädler S, Hrabé de Angelis M, Seliger B and Beckers J

    Helmholtz Zentrum München-German Research Center for Environmental Health (GmbH), Institute of Experimental Genetics, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany.

    Ras acts in signalling pathways regulating the activity of multiple cellular functions including cell proliferation, differentiation, and apoptosis. Amino-acid exchanges at position 12, 13, or 61 of the Kras gene convert the proto-oncogene into an activated oncogene. Until now, a direct comparison of genome-wide expression profiling studies of Kras overexpression and different Kras mutant forms in a single assay system has not been carried out. In our study, we focused on the direct comparison of global gene expression effects caused by mutations in codon 12 or 13 of the Kras gene and Kras overexpression in murine fibroblasts. We determined Kras cellular mRNA, Ras protein and activated Ras protein levels. Further, we compared our data to the proteome analysis of the same transfected cell lines. Both overexpression and mutations of Kras lead to common altered gene expression patterns. Only two genes, Lox and Col1a1, were reversely regulated in the Kras transfectants. They may contribute to the higher aggressiveness of the Kras codon 12 mutation in tumour progression. The functional annotation of differentially expressed genes revealed a high frequency of proteins involved in tumour growth and angiogenesis. These data further support the important role of these genes in tumour-associated angiogenesis.

    British journal of cancer 2009;100;4;656-62

  • K-ras mutations and cetuximab in colorectal cancer.

    Marchetti A and Gasparini G

    The New England journal of medicine 2009;360;8;833-4; author reply 835-6

  • Distinct BRAF (V600E) and KRAS mutations in high microsatellite instability sporadic colorectal cancer in African Americans.

    Kumar K, Brim H, Giardiello F, Smoot DT, Nouraie M, Lee EL and Ashktorab H

    Department of Medicine and Cancer Center, Howard University, Washington, District of Columbia 20060, USA.

    Purpose: Colorectal cancer develops through genetic, epigenetic, and environmental events that result in uncontrolled cell proliferation. Colorectal cancer incidence and mortality is higher in African Americans (AA) than in the general population. Here, we carried out a molecular analysis of sporadic colorectal cancer tumors from AAs to investigate possible explanations for the observed disparities.

    A total of 222 AA colorectal cancer tumors were analyzed for microsatellite instability (MSI) for protein expression of two DNA mismatch repair genes, MLH1 and MSH2, by immunohistochemistry; for the methylation silencing of MLH1, p16, APC, and APC2 promoters by methylation-specific PCR; and for point mutations in two oncogenes, KRAS and BRAF, by sequencing.

    Results: In our sample, 19.8% of the AAs colorectal cancer tumors were MSI high (MSI-H) and did not associate with any of the clinicopathologic features, except tumor differentiation. Higher levels of inactive DNA mismatch repair proteins MLH1 (41%) and MSH2 (33%) were found by immunohistochemistry. Methylation-specific PCR analysis revealed a high level of methylation for MLH1 (66%), APC (53%), and APC2 (90%), but not for p16 (26%). BRAF mutations were only within the MSI-H tumors, whereas most (64%) of KRAS mutations were found within the non-MSI-H group.

    Conclusions: MLH1, MSH2, and BRAF alterations are significantly associated with MSI-H phenotype, unlike APC, APC2 and KRAS alterations. The prominent role of DNA mismatch repair gene suppression in MSI-H and a distinctive role of BRAF and KRAS mutations with respect to MSI status are supported by this study.

    Funded by: NCI NIH HHS: CA102681, P50 CA062924-139003, P50 CA062924-149003, R01 CA102681

    Clinical cancer research : an official journal of the American Association for Cancer Research 2009;15;4;1155-61

  • Chemotherapy, bevacizumab, and cetuximab in metastatic colorectal cancer.

    Tol J, Koopman M, Cats A, Rodenburg CJ, Creemers GJ, Schrama JG, Erdkamp FL, Vos AH, van Groeningen CJ, Sinnige HA, Richel DJ, Voest EE, Dijkstra JR, Vink-Börger ME, Antonini NF, Mol L, van Krieken JH, Dalesio O and Punt CJ

    Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.

    Background: Fluoropyrimidine-based chemotherapy plus the anti-vascular endothelial growth factor (VEGF) antibody bevacizumab is standard first-line treatment for metastatic colorectal cancer. We studied the effect of adding the anti-epidermal growth factor receptor (EGFR) antibody cetuximab to a combination of capecitabine, oxaliplatin, and bevacizumab for metastatic colorectal cancer.

    Methods: We randomly assigned 755 patients with previously untreated metastatic colorectal cancer to capecitabine, oxaliplatin, and bevacizumab (CB regimen, 378 patients) or the same regimen plus weekly cetuximab (CBC regimen, 377 patients). The primary end point was progression-free survival. The mutation status of the KRAS gene was evaluated as a predictor of outcome.

    Results: The median progression-free survival was 10.7 months in the CB group and 9.4 in the CBC group (P=0.01). Quality-of-life scores were lower in the CBC group. The overall survival and response rates did not differ significantly in the two groups. Treated patients in the CBC group had more grade 3 or 4 adverse events, which were attributed to cetuximab-related adverse cutaneous effects. Patients treated with cetuximab who had tumors bearing a mutated KRAS gene had significantly decreased progression-free survival as compared with cetuximab-treated patients with wild-type-KRAS tumors or patients with mutated-KRAS tumors in the CB group.

    Conclusions: The addition of cetuximab to capecitabine, oxaliplatin, and bevacizumab resulted in significantly shorter progression-free survival and inferior quality of life. Mutation status of the KRAS gene was a predictor of outcome in the cetuximab group. (ClinicalTrials.gov number, NCT00208546.)

    The New England journal of medicine 2009;360;6;563-72

  • Clonality, founder mutations, and field cancerization in human ulcerative colitis-associated neoplasia.

    Leedham SJ, Graham TA, Oukrif D, McDonald SA, Rodriguez-Justo M, Harrison RF, Shepherd NA, Novelli MR, Jankowski JA and Wright NA

    Histopathology Unit, Cancer Research UK, London, United Kingdom. simon.leedham@cancer.org.uk

    The clonality of colitis-associated neoplasia has not been fully determined. One previous report showed polyclonal origins with subsequent monoclonal outgrowth. We aimed to assess the clonality and mutation burden of individual crypts in colitis-associated neoplasias to try to identify gatekeeping founder mutations, and explore the clonality of synchronous lesions to look for field effects.

    Methods: Individual crypts (range, 8-21 crypts) were microdissected from across 17 lesions from 10 patients. Individual crypt adenomatous polyposis coli (APC), p53, K-RAS, and 17p loss of heterozygosity mutation burden was established using polymerase chain reaction and sequencing analysis. Serial sections underwent immunostaining for p53, beta-catenin, and image cytometry to detect aneuploidy.

    Results: In most lesions an oncogenic mutation could be identified in all crypts across the lesion showing monoclonality. This founder mutation was a p53 lesion in the majority of neoplasms but 4 tumors had an initiating K-RAS mutation. Some nondysplastic crypts surrounding areas of dysplasia were found to contain clonal p53 mutations and in one case 3 clonal tumors arose from a patch of nondysplastic crypts containing a K-RAS mutation.

    Conclusions: This study used mutation burden analysis of individual crypts across colitis-associated neoplasms to show lesion monoclonality. This study confirmed p53 mutation as initiating mutation in the majority of lesions, but also identified K-RAS activation as an alternative gatekeeping mutation. Local and segmental field cancerization was found by showing pro-oncogenic mutations in nondysplastic crypts surrounding neoplasms, although field changes are unlikely to involve the entire colon because widely separated tumors were genetically distinct.

    Funded by: Cancer Research UK; Medical Research Council

    Gastroenterology 2009;136;2;542-50.e6

  • Cognitive profile of disorders associated with dysregulation of the RAS/MAPK signaling cascade.

    Cesarini L, Alfieri P, Pantaleoni F, Vasta I, Cerutti M, Petrangeli V, Mariotti P, Leoni C, Ricci D, Vicari S, Selicorni A, Tartaglia M, Mercuri E and Zampino G

    Pediatric Neurology Unit, Catholic University, Rome, Italy.

    Mutations in genes coding for transducers participating in the RAS/MAPK pathway have been identified as the molecular cause underlying a group of clinically related developmental disorders with cognitive deficits of variable severity. To determine the spectrum of cognitive defects associated with dysregulation of this signal cascade, we studied the profile of cognitive abilities in patients with mutations affecting the PTPN11, SOS1, HRAS, KRAS, BRAF, RAF1, and MEK1 genes and phenotype-genotype correlations. Our findings support the observation that heterogeneity in cognitive abilities can be at least partially ascribed to the individual affected genes and type of mutation involved. While mutations affecting transducers upstream of RAS were less frequently associated with mental retardation, mutations in downstream components of the pathway were generally associated with a more severe cognitive impairment. Among patients with a heterozygous PTPN11 mutation, the T468M substitution was associated with a mean IQ significantly higher compared to that of individuals carrying the N308D change. Our study provides insights on the range of cognitive abilities in patients with gene mutations causing dysregulation of RAS signaling suggesting that the presence and severity of cognitive involvement can be predicted in part by the gene involved.

    Funded by: Telethon: GGP07115

    American journal of medical genetics. Part A 2009;149A;2;140-6

  • High detection rates of colorectal neoplasia by stool DNA testing with a novel digital melt curve assay.

    Zou H, Taylor WR, Harrington JJ, Hussain FT, Cao X, Loprinzi CL, Levine TR, Rex DK, Ahnen D, Knigge KL, Lance P, Jiang X, Smith DI and Ahlquist DA

    Miles and Shirley Fiterman Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota 55905, USA. zou.hongzhi@mayo.edu

    Current stool DNA tests identify about half of individuals with colorectal cancers and miss most individuals with advanced adenomas. We developed a digital melt curve (DMC) assay to quantify low-abundance mutations in stool samples for detection of colorectal neoplasms and compared this test with other approaches.

    Methods: We combined a melt curve assay with digital polymerase chain reaction and validated the quantitative range. We then evaluated its ability to detect neoplasms in 2 clinical studies. In study I, stool samples from patients with colorectal tumors with known mutations (KRAS, APC, BRAF, TP53) were assayed. In study II, archived stool samples from patients with advanced adenomas containing known KRAS mutations were assayed, along with controls. Results were compared with those from the stool DNA test PreGenPlus (Exact Sciences, Marlborough, MA), Hemoccult, and HemoccultSensa (both Beckman-Coulter, Fullerton, CA).

    Results: The DMC assay detected samples in which only 0.1% of target genes were mutated. In study I, the DMC assay detected known mutations in 28 (90%) of 31 tumor samples and 6 (75%) of 8 advanced adenoma samples. In study II, the DMC assay detected 16 (59%) of 27 advanced adenoma samples that contained KRAS mutations, compared with 7% with the Hemoccult, 15% with the HemoccultSensa, and 26% with the PreGenPlus assays (P < .05 for each, compared with the DMC assay); specificities did not differ significantly.

    Conclusions: The DMC assay has a high level of sensitivity in detecting individuals with colon neoplasms and is better than current stool screening methods in detecting those with advanced adenomas. Further studies are indicated.

    Gastroenterology 2009;136;2;459-70

  • [K-ras mutation predictive significance in platinum based chemotherapeutic protocols in patients with advanced non-small cell lung cancer].

    Cvetković G, Plavec G, Tomić I, Ilić V, Magić Z, Tatomirović Z, Novković D, Milić R and Karlicić V

    Vojnomedicinska akademija, Klinika za plućne bolesti, Beograd.

    K-ras oncogene is mutated in about 20% of lung cancer. The purpose of this study was to investigate the predictive significance for therapeutic response of K-ras mutations in advanced non-small cell lung cancer (NSCLC) patients.

    Methods: Bronchial aspirate samples were assessed prior to platinum-based chemotherapy start in 39 patients with stage IIIb or IV NSCLC. K-ras mutations at codons 12 and 13 were analyzed by single strand conformation polymorphisam (SSCP) and allele specific oligonucleozide hybridisation of polymerase chain reaction (PCR) of the patient's DNA present in bronchial aspirate. After two cycles of chemotherapy the patients were subjected to response evaluation.

    Results: Of 39 patients 10 (25.5%) demonstrated K-ras mutations, while 29 (74.4%) patients had not. There were no significant differences between these two groups of patients with respect to baseline patient caracteristics. Partial response to the therapy had 16 (41%), no changes 14 (36%), and progressive disease 9 (23%) patients. There was a tendency to higher response rate for patients without K-ras mutations versus those with mutations, but not statistically significant (p = 0.14).

    Conclusion: There was no significant predictive value for therapeutic response of K-ras mutations for advanced non-small cell lung cancer.

    Vojnosanitetski pregled 2009;66;2;149-55

  • KRAS2 mutations in human pancreatic acinar-ductal metaplastic lesions are limited to those with PanIN: implications for the human pancreatic cancer cell of origin.

    Shi C, Hong SM, Lim P, Kamiyama H, Khan M, Anders RA, Goggins M, Hruban RH and Eshleman JR

    The Sol Goldman Pancreatic Cancer Research Center, Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, MD 212312, USA.

    Pancreatic intraepithelial neoplasia (PanIN) is a precursor to invasive ductal adenocarcinoma of the pancreas. Observations made in genetically engineered mouse models suggest that the acinar/centroacinar compartment can give rise to ductal neoplasia. To integrate findings in mice and men, we examined human acinar cells, acinar-ductal metaplasia (ADM) lesions, and PanINs for KRAS2 gene mutations. Surgically resected pancreata were screened for foci of ADM with or without an associated PanIN lesion. Stromal cells, acinar cells, ADMs, and PanINs were separately isolated using laser capture microdissection. KRAS2 status was analyzed using genomic DNA isolated from the microdissected tissue. Twelve of these 31 foci of ADM occurred in isolation, whereas 19 were in the same lobules as a PanIN lesion. All 31 microdissected foci of acinar cells were KRAS2 gene wild-type, as were all 12 isolated ADM lesions lacking an associated PanIN. KRAS2 gene mutations were present in 14 of 19 (74%) PanIN lesions and in 12 of the 19 (63%) foci of ADM associated with these PanINs. All ADM lesions with a KRAS2 gene mutation harbored the identical KRAS2 gene mutation found in their associated PanIN lesions. Ductal neoplasms of the human pancreas, as defined by KRAS2 gene mutations, do not appear to arise from acinar cells. Isolated AMD lesions are genetically distinct from those associated with PanINs, and the latter may represent retrograde extension of the neoplastic PanIN cells or less likely are precursors to PanIN.

    Funded by: NCI NIH HHS: CA62924, P50 CA062924-15

    Molecular cancer research : MCR 2009;7;2;230-6

  • RAS and RAF mutations in banal melanocytic aggregates contiguous with primary cutaneous melanoma: clues to melanomagenesis.

    Dadzie OE, Yang S, Emley A, Keady M, Bhawan J and Mahalingam M

    Dermatopathology Section, Department of Dermatology, Boston University School of Medicine, 609 Albany Street, J-301, Boston, MA 02118, USA.

    Background: Distinguishing banal melanocytic aggregates contiguous with malignant melanoma can be a histological challenge but is essential because of the potential for a spurious Breslow measurement.

    Objectives: Our aim was to ascertain whether the histological distinction between the two relates to differences in the prevalence of mutations in genes significant in melanomagenesis.

    Methods: Mutations in BRAF codon 600, NRAS1 codons 12/13, NRAS2 codons 60/61 and KRAS codons 12/13 were ascertained in 18 cases of primary cutaneous malignant melanoma contiguous with banal melanocytic aggregates using laser capture microdissection.

    Results: Overall, 12 of 18 cases (67%) exhibited a mutation in at least one gene. BRAF V600E appeared to be the most commonly mutated gene in both the melanocytic aggregate (seven of 18, 39%) and the melanoma (four of 18, 22%). Both populations demonstrated a similar BRAF genomic profile in 11 of 18 cases (61%) (two BRAF V600E, nine BRAF-WT), a similar KRAS genomic profile in 14 of 18 cases (78%) (one KRAS G12V, 13 KRAS-WT) and a similar NRAS2 genomic profile in 14 of 18 cases (all WT). Of interest, we noted a relatively high prevalence of KRAS mutations (five of 18, 28%). The frequency of KRAS mutations in the melanocytic aggregate (five of 18, 28%) was second to BRAF V600E, while in melanoma, the frequency was also second to BRAF V600E but equalled that of NRAS2 (1 of 18, 6%). No NRAS1 mutations were observed. BRAF and RAS mutations appeared to be mutually exclusive with only three of 18 cases (17%) demonstrating a mutation in both genes (melanocytic aggregate only).

    Conclusions: Our findings hint towards the interpretation of banal melanocytic aggregates serving as precursor lesions.

    The British journal of dermatology 2009;160;2;368-75

  • The clinical benefit of bevacizumab in metastatic colorectal cancer is independent of K-ras mutation status: analysis of a phase III study of bevacizumab with chemotherapy in previously untreated metastatic colorectal cancer.

    Hurwitz HI, Yi J, Ince W, Novotny WF and Rosen O

    Duke University Medical Center, Division of Hematology & Oncology, Durham, NC 27710-0001, USA. hurwi004@mc.duke.edu

    Purpose: Mutations of the K-ras gene were identified as a prognostic marker in metastatic colorectal cancer (mCRC). In addition, emerging data suggest that K-ras mutations are a negative predictor of clinical benefit from anti-epidermal growth factor receptor treatment in mCRC. Previously reported data suggest that the longer overall survival (OS) observed with bevacizumab treatment in mCRC is independent of alterations in the Ras/Raf/Mek/Erk pathway. We conducted additional analyses to better describe the clinical benefit of bevacizumab treatment in mCRC relative to K-ras mutation status.

    Additional statistical analyses were done with data from K-ras mutation analyses in 230 patients who were treated with irinotecan, fluorouracil, and leucovorin (IFL) in combination with either bevacizumab or placebo in a randomized phase III study. Following microdissection, tissue was subject to DNA sequencing to identify K-ras mutations in codons 12 and 13. Hazard ratios for the bevacizumab group relative to the control group were estimated from an unstratified Cox regression model. The median progression-free survival (PFS), OS times, and objective response rates were compared.

    Results: K-ras status was assessed in 230 patients (28.3%). The median PFS was significantly longer in bevacizumab-treated patients with wild-type (wt)- (13.5 versus 7.4 months; hazard ratio 0.44, p < .0001) and mutant (m)-K-ras (9.3 versus 5.5 months; hazard ratio 0.41, p = .0008). A significantly higher response rate for IFL plus bevacizumab was observed only in wt-K-ras patients (60.0% versus 37.3%, p = .006) compared with 43.2% versus 41.2% in the m-K-ras group.

    Conclusion: Bevacizumab provides significant clinical benefit in patients with mCRC expressing either mutant or wild-type K-ras.

    The oncologist 2009;14;1;22-8

  • PI3KCA/PTEN deregulation contributes to impaired responses to cetuximab in metastatic colorectal cancer patients.

    Perrone F, Lampis A, Orsenigo M, Di Bartolomeo M, Gevorgyan A, Losa M, Frattini M, Riva C, Andreola S, Bajetta E, Bertario L, Leo E, Pierotti MA and Pilotti S

    Experimental Molecular Pathology, Department of Pathology, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.

    Background: It has been reported that KRAS mutations (and to a lesser extent KRAS mutations with the BRAF V600E mutation) negatively affect response to anti-epidermal growth factor receptor (EGFR) mAbs in metastatic colorectal cancer (mCRC) patients, while the biological impact of the EGFR pathway represented by PI3K/PTEN/AKT on anti-EGFR treatment is still not clear.

    We analysed formalin-fixed samples from a cohort of 32 mCRC patients treated with cetuximab by means of EGFR immunohistochemistry, EGFR and PTEN FISH analysis, and KRAS, BRAF, PI3KCA, and PTEN genomic sequencing.

    Results: Ten (31%) of 32 patients showed a partial response to cetuximab and 22 (69%) did not [nonresponder (NR)]. EGFR immunophenotype and FISH-based gene status did not predict an anti-EGFR mAb response, whereas KRAS mutations (24%) and PI3K pathway activation, by means of PI3KCA mutations (13%) or PTEN mutation (10%)/loss (13%), were significantly restricted to, respectively, 41% and 37% of NRs.

    Conclusion: These findings suggested that KRAS mutations and PI3KCA/PTEN deregulation significantly correlate with resistance to cetuximab. In line with this, patients carrying KRAS mutations or with activated PI3K profiles can benefit from targeted treatments only by switching off molecules belonging to the downstream signalling of activated EGFR, such as mammalian target of rapamycin.

    Annals of oncology : official journal of the European Society for Medical Oncology 2009;20;1;84-90

  • Prognostic implication of EGFR, KRAS, and TP53 gene mutations in a large cohort of Japanese patients with surgically treated lung adenocarcinoma.

    Kosaka T, Yatabe Y, Onozato R, Kuwano H and Mitsudomi T

    Department of Thoracic Surgery, Aichi Cancer Center Hospital, Nagoya, Japan.

    Introduction: Although mutation of the epidermal growth factor receptor (EGFR) gene is predictive for the response to EGFR-tyrosine kinase inhibitor, its prognostic impact for patients without EGFR-tyrosine kinase inhibitor treatment remains controversial. We examined for EGFR, KRAS or TP53 mutations in a consecutive large cohort of patients with lung adenocarcinoma, and evaluated their prognostic impact.

    Methods: We analyzed 397 patients with lung adenocarcinoma who underwent potentially curative pulmonary resection. Total ribonucleic acid was extracted and direct sequencing of each gene was performed after reverse transcription-polymerase chain reaction.

    Results: We found that 196 patients (49%) had EGFR mutations. Of these, 83 were exon 19 deletions (42%) and 92 were L858R (47%). Univariate analysis showed that patients with EGFR mutations survived for a longer period than those without mutations (p = 0.0046). However, there was no difference in overall survival between the patients with exon 19 deletion and those with L858R (p = 0.4144). Patients with KRAS mutations or TP53 mutations tended to survive for a shorter period (p = 0.2183 and 0.0230, respectively). Multivariate analysis using the Cox proportional hazards model revealed that smoking status (p = 0.0310) and disease stage (p < 0.0001) were independent prognostic factors. However, none of the gene mutations was independent prognostic factors (EGFR, p = 0.3225; KRAS, p = 0.8500; TP53, p = 0.3191).

    Conclusions: EGFR, KRAS, and TP53 gene mutations were not independently associated with the prognosis for Japanese patients with surgically treated lung adenocarcinoma.

    Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer 2009;4;1;22-9

  • Role of 3'-phosphoinositides in oncogenic KRAS-induced modulation of shape and motility of airway epithelial cells.

    Okudela K, Yazawa T, Suzuki T, Sugimura H and Kitamura H

    Department of Pathology, Yokohama City University Graduate School of Medicine, Yokohama, Japan.

    The authors' previous study demonstrated that oncogenic KRAS modulates the shape and motility of airway epithelial cells. To explore detailed mechanism mediating these events, the possible involvement of phosphatidylinositides (PIP) was investigated. The intracellular localization of PIP was visualized with a pleckstrin homology domain-enhanced green fluorescent protein (EGFP) construct. PIP accumulated at the leading edges of polarizing epithelial cells, while they co-localized with cortical actin at cell-cell contacts, suggesting that PIP play important roles in the cytoskeletal organization. Transduction of oncogenic KRAS induced multiple pseudopodia and disrupted cortical actin, enhancing motility. A mitogen activated protein kinase kinase (MEK) inhibitor reduced the accumulation of PIP at membranes and development of pseudopodia, and restored stable cortical actin, reducing the motility. A phosphoinositide 3-kinase (PI3K) inhibitor also reduced accumulation of PIP at membranes, formation of pseudopodia and motility, but its effect on cortical actin was indistinct. The KRAS V12/S35 mutant, activating only the MEK pathway, induced multiple pseudopodia and disrupted the cortical actin. The KRAS V12/C40 mutant, activating only the PI3K pathway, also induced pseudopodia, but its effect on cortical actin was obscure. Taken together, oncogenic KRAS could cause the accumulation of PIP via the PI3K and MEK pathways and modulate the cell shape and migration.

    Pathology international 2009;59;1;28-37

  • Using whole genome amplification (WGA) of low-volume biopsies to assess the prognostic role of EGFR, KRAS, p53, and CMET mutations in advanced-stage non-small cell lung cancer (NSCLC).

    Lim EH, Zhang SL, Li JL, Yap WS, Howe TC, Tan BP, Lee YS, Wong D, Khoo KL, Seto KY, Tan L, Agasthian T, Koong HN, Tam J, Tan C, Caleb M, Chang A, Ng A and Tan P

    Johns Hopkins Singapore International Medical Centre, Singapore. elaine_h_lim@yahoo.com

    Background: Progression of non-small cell lung cancer (NSCLC) from early- to late-stage may signify the accumulation of gene mutations. An advanced-stage tumor's mutation profile may also have prognostic value, guiding treatment decisions. Mutation detection of multiple genes is limited by the low amount of deoxyribonucleic acid extracted from low-volume diagnostic lung biopsies. We explored whole genome amplification (WGA) to enable multiple molecular analyses.

    Methods: Eighty-eight advanced-stage NSCLC patients were enrolled. Their low-volume lung biopsies underwent WGA before direct sequencing for epidermal growth factor receptor (EGFR), KRAS (rat sarcoma virus), p53, and CMET (mesenchymal-epithelial transition factor) mutations. Overall survival impact was examined. Surgically-resected tumors from 133 early-stage NSCLC patients were sequenced for EGFR, KRAS and p53 mutations. We compared the mutation frequencies of both groups.

    Results: It is feasible for low-volume lung biopsies to undergo WGA for mutational analysis. KRAS and CMET mutations have a deleterious effect on overall survival, hazard ratios 5.05 (p = 0.009) and 23.65 (p = 0.005), respectively. EGFR and p53 mutations, however, do not have a survival impact. There also does not seem to be significant differences in the frequency of mutations in EGFR, KRAS, and p53 between early- and advanced-stage disease: 20% versus 24% (p = 0.48), 29% versus 27% (p = 0.75), 10% versus 6% (p = 0.27), respectively.

    Conclusions: In advanced-stage NSCLC, KRAS, and CMET mutations suggest poor prognosis, whereas EGFR and p53 mutations do not seem to have survival impact. Mutations in EGFR, KRAS and p53 are unlikely to be responsible for the progression of NSCLC from early- to late-stage disease. WGA may be used to expand starting deoxyribonucleic acid from low-volume lung biopsies for further analysis of advanced-stage NSCLC.

    Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer 2009;4;1;12-21

  • A fast, sensitive and accurate high resolution melting (HRM) technology-based assay to screen for common K-ras mutations.

    Kramer D, Thunnissen FB, Gallegos-Ruiz MI, Smit EF, Postmus PE, Meijer CJ, Snijders PJ and Heideman DA

    Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands.

    Background: Increasing evidence points to a negative correlation between K-ras mutations and patient's response to, or survival benefit after, treatment with EGFR-inhibitors. Therefore, rapid and reliable assays for mutational analysis of the K-ras gene are strongly needed.

    Methods: We designed a high resolution melting (HRM) technology-based approach followed by direct sequencing to determine K-ras exon 1 (codons 12/13) tumour genotype.

    Results: Reconstruction experiments demonstrated an analytical sensitivity of the K-ras exon 1 HRM assay following sequencing of 1.5-2.5% of mutated DNA in a background of wild-type DNA. Assay reproducibility and accuracy were 100%. Application of the HRM assay following sequencing onto genomic DNA isolated from formalin-fixed paraffin-embedded tumour specimens of non-small cell lung cancer (n=91) and colorectal cancer (n=7) patients revealed nucleotide substitutions at codons 12 or 13, including a homozygous mutation, in 33 (34%) and 5 (5%) cases, respectively. Comparison to conventional nested-PCR following cycle-sequencing showed an overall high agreement in genotype findings (kappa value of 0.96), with more mutations detected by the HRM assay following sequencing.

    Conclusions: HRM allows rapid, reliable and sensitive pre-screening of routine diagnostic specimens for subsequent genotyping of K-ras mutations, even if present at low abundance or homozygosity, and may considerably facilitate personalized therapy planning.

    Cellular oncology : the official journal of the International Society for Cellular Oncology 2009;31;3;161-7

  • The role of KRAS mutations in predicting the efficacy of cetuximab-plus-irinotecan therapy in irinotecan-refractory Korean metastatic colorectal cancer patients.

    Sohn BS, Kim TW, Lee JL, Ryu MH, Chang HM, Kang YK, Park HS, Na YS, Jang SJ, Kim JC and Lee JS

    Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

    Objective: This study evaluated the clinical relevance of KRAS and BRAF mutational status in 66 irinotecan-refrac- tory Korean metastatic colorectal cancer (mCRC) patients treated with cetuximab-plus-irinotecan-based chemotherapy.

    Methods: A total of 66 irinotecan-refractory mCRC patients treated with cetuximab-plus-irinotecan-based chemotherapy were included. Tumors were screened for KRAS mutations (codons 12 and 13) and a BRAF mutation (V600E) using direct sequencing and the Snapshot assay.

    Results: The objective response rate (RR) for treatment was 21.2% (14/66) and skin rashes were observed in 43 (65.2%) of the 66 patients. A KRAS mutation was detected in 27 (40.9%) tumors, and was associated with lower RR (wild-type vs. mutated KRAS: 33.3 vs. 3.7%, p = 0.005) and shorter progression-free survival (PFS) and overall survival (OS; PFS: 6.4 vs. 2.0 months, p = 0.005; OS: 17.8 vs. 7.1 months, p = 0.001). Severe skin toxicity was associated with better RR and longer PFS and OS. BRAF mutations were not detected. Multivariate analysis revealed that KRAS status and skin toxicity were independent predictive factors of PFS and OS.

    Conclusions: This study indicates the clinical relevance of KRAS mutations in predicting the efficacy of cetuximab-plus-irinotecan-based chemotherapy in irinotecan-refractory Korean mCRC patients.

    Oncology 2009;77;3-4;224-30

  • Alterations in genes of the EGFR signaling pathway and their relationship to EGFR tyrosine kinase inhibitor sensitivity in lung cancer cell lines.

    Gandhi J, Zhang J, Xie Y, Soh J, Shigematsu H, Zhang W, Yamamoto H, Peyton M, Girard L, Lockwood WW, Lam WL, Varella-Garcia M, Minna JD and Gazdar AF

    Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America.

    Background: Deregulation of EGFR signaling is common in non-small cell lung cancers (NSCLC) and this finding led to the development of tyrosine kinase inhibitors (TKIs) that are highly effective in a subset of NSCLC. Mutations of EGFR (mEGFR) and copy number gains (CNGs) of EGFR (gEGFR) and HER2 (gHER2) have been reported to predict for TKI response. Mutations in KRAS (mKRAS) are associated with primary resistance to TKIs.

    We investigated the relationship between mutations, CNGs and response to TKIs in a large panel of NSCLC cell lines. Genes studied were EGFR, HER2, HER3 HER4, KRAS, BRAF and PIK3CA. Mutations were detected by sequencing, while CNGs were determined by quantitative PCR (qPCR), fluorescence in situ hybridization (FISH) and array comparative genomic hybridization (aCGH). IC50 values for the TKIs gefitinib (Iressa) and erlotinib (Tarceva) were determined by MTS assay. For any of the seven genes tested, mutations (39/77, 50.6%), copy number gains (50/77, 64.9%) or either (65/77, 84.4%) were frequent in NSCLC lines. Mutations of EGFR (13%) and KRAS (24.7%) were frequent, while they were less frequent for the other genes. The three techniques for determining CNG were well correlated, and qPCR data were used for further analyses. CNGs were relatively frequent for EGFR and KRAS in adenocarcinomas. While mutations were largely mutually exclusive, CNGs were not. EGFR and KRAS mutant lines frequently demonstrated mutant allele specific imbalance i.e. the mutant form was usually in great excess compared to the wild type form. On a molar basis, sensitivity to gefitinib and erlotinib were highly correlated. Multivariate analyses led to the following results: 1. mEGFR and gEGFR and gHER2 were independent factors related to gefitinib sensitivity, in descending order of importance. 2. mKRAS was associated with increased in vitro resistance to gefitinib.

    Our in vitro studies confirm and extend clinical observations and demonstrate the relative importance of both EGFR mutations and CNGs and HER2 CNGs in the sensitivity to TKIs.

    Funded by: NCI NIH HHS: P50CA70907, U01CA084971

    PloS one 2009;4;2;e4576

  • Colorectal carcinomas in MUTYH-associated polyposis display histopathological similarities to microsatellite unstable carcinomas.

    Nielsen M, de Miranda NF, van Puijenbroek M, Jordanova ES, Middeldorp A, van Wezel T, van Eijk R, Tops CM, Vasen HF, Hes FJ and Morreau H

    Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands. M.Nielsen@lumc.nl

    Background: MUTYH-associated polyposis (MAP) is a recessively inherited disorder which predisposes biallelic carriers for a high risk of polyposis and colorectal carcinoma (CRC). Since about one third of the biallelic MAP patients in population based CRC series has no adenomas, this study aimed to identify specific clinicopathological characteristics of MAP CRCs and compare these with reported data on sporadic and Lynch CRCs.

    Methods: From 44 MAP patients who developed > or = 1 CRCs, 42 of 58 tumours were analyzed histologically and 35 immunohistochemically for p53 and beta-catenin. Cell densities of CD3, CD8, CD57, and granzyme B positive lymphocytes were determined. KRAS2, the mutation cluster region (MCR) of APC, p53, and SMAD4 were analyzed for somatic mutations.

    Results: MAP CRCs frequently localized to the proximal colon (69%, 40/58), were mucinous in 21% (9/42), and had a conspicuous Crohn's like infiltrate reaction in 33% (13/40); all of these parameters occurred at a higher rate than reported for sporadic CRCs. Tumour infiltrating lymphocytes (TILs) were also highly prevalent in MAP CRCs. Somatic APC MCR mutations occurred in 14% (5/36) while 64% (23/36) had KRAS2 mutations (22/23 c.34G>T). G>T transversions were found in p53 and SMAD4, although the relative frequency compared to other mutations was low.

    Conclusion: MAP CRCs show some similarities to micro-satellite unstable cancers, with a preferential proximal location, a high rate of mucinous histotype and increased presence of TILs. These features should direct the practicing pathologist towards a MAP aetiology of CRC as an alternative for a mismatch repair deficient cause. High frequent G>T transversions in APC and KRAS2 (mutated in early tumour development) but not in P53 and SMAD4 (implicated in tumour progression) might indicate a predominant MUTYH effect in early carcinogenesis.

    BMC cancer 2009;9;184

  • Expression of activated PIK3CA in ovarian surface epithelium results in hyperplasia but not tumor formation.

    Liang S, Yang N, Pan Y, Deng S, Lin X, Yang X, Katsaros D, Roby KF, Hamilton TC, Connolly DC, Coukos G and Zhang L

    Center for Research on the Early Detection and Cure of Ovarian Cancer, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America.

    Background: The Phosphatidylinositol 3'-kinase is a key regulator in various cancer-associated signal transduction pathways. Genetic alterations of its catalytic subunit alpha, PIK3CA, have been identified in ovarian cancer. Our in vivo data suggests that PIK3CA activation is one of the early genetic events in ovarian cancer. However, its role in malignant transformation of ovarian surface epithelium (OSE) is largely unclear.

    Using the Müllerian inhibiting substance type II receptor (MISIIR) promoter, we generated transgenic mice that expressed activated PIK3CA in the Müllerian epithelium. Overexpression of PIK3CA in OSE induced remarkable hyperplasia, but was not able to malignantly transform OSE in vivo. The consistent result was also observed in primary cultured OSEs. Although enforced expression of PIK3CA could not induce OSE anchorage-independent growth, it significantly increased anchorage-independent growth of OSE transformed by mutant K-ras.

    While PIK3CA activation may not be able to initiate OSE transformation, we conclude that activation of PIK3CA may be an important molecular event contributing to the maintenance of OSE transformation initiated by oncogenes such as K-ras.

    Funded by: NCI NIH HHS: P50 CA083638, P50-CA83638, R01 CA142776

    PloS one 2009;4;1;e4295

  • Frequency and type of KRAS mutations in routine diagnostic analysis of metastatic colorectal cancer.

    Neumann J, Zeindl-Eberhart E, Kirchner T and Jung A

    Department of Pathology, Ludwig-Maximilians Universität München, Thalkirchner Strasse 36, 80337 Munich, Germany. jens.neumann@med.uni-muenchen.de

    Mutation analysis of the KRAS oncogene is now established as a predictive biomarker in colorectal cancer (CRC). Large prospective clinical trials have shown that only CRCs with wild-type KRAS respond to anti-epidermal growth factor receptor (EGFR) treatment. Therefore, mutation analysis is mandatory before treatment, and reliable benchmarks for the frequency and types of KRAS mutations have to be established for routinely testing large numbers of metastatic CRCs. A thousand and eighteen cases (879 primary tumors and 139 metastases) of metastatic colorectal cancer were analyzed for the KRAS mutational status of codons 12 and 13 of the KRAS gene by genomic sequencing in a routine setting. Results were analyzed separately for specimens derived from primary tumors and metastases. KRAS mutations in codons 12 and 13 were present in 39.3% of all analyzed CRCs. The most frequent types of mutations were glycine to aspartate on codon 12 (p.G12D, 36.0%), glycine to valine on codon 12 (pG12V, 21.8%), and glycine to aspartate on codon 13 (p.G13D, 18.8%). They account for 76.6% of all mutations and prevail in primary tumors and distant metastases, indicating a robustness of the KRAS mutational status during neoplastic dissemination. The frequency of KRAS mutations and the preponderance of three types of mutations in codons 12 and 13 in a large, unselected cohort of metastatic CRC confirm the previous data of small and selected CRC samples. Thus, a mutation frequency of 40% and a cluster of three mutation types (p.G12D, pG12V, and p.G13D) in primaries and metastases can be defined as benchmarks for routine KRAS analyses.

    Pathology, research and practice 2009;205;12;858-62

  • Genetic analysis of Alzheimer's disease in the Uppsala Longitudinal Study of Adult Men.

    Giedraitis V, Kilander L, Degerman-Gunnarsson M, Sundelöf J, Axelsson T, Syvänen AC, Lannfelt L and Glaser A

    Molecular Geriatrics, Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden. vilmantas.giedraitis@pubcare.uu.se

    Genetic factors influencing common complex conditions have proven difficult to identify, and data from numerous investigations have provided incomplete conclusions as to the identity of these genes. Here we aimed to identify susceptibility genes for late-onset Alzheimer's disease (AD).

    Methods: The case-control analysis included samples from 86 AD patients and 404 cognitively healthy controls selected from the Uppsala Longitudinal Study of Adult Men (ULSAM). In the incidence analysis, all 1,088 genotyped ULSAM participants were included. DNA samples from ULSAM participants were analyzed for 2,578 single nucleotide polymorphisms (SNP) within 368 genes. The selection of genes tested for association to AD within this cohort was based on genes previously implicated in conditions with relevance to ULSAM, such as dementia, cardiovascular disease, diabetes and metabolic syndrome, osteoporosis, and cancer.

    Association analysis revealed 82 genes containing at least 1 significant SNP at p < 0.05 with association to AD. Only 20 genes remained significant after a permutation test to correct for multiple comparisons within individual genes. Using publicly available data from 2 genome-wide association (GWA) studies and linkage disequilibrium data from HapMap, we attempted to replicate the AD association identified in ULSAM. In addition to apolipoprotein E, we were able to replicate 5 other genes in both GWA studies at p < 0.05.

    Dementia and geriatric cognitive disorders 2009;27;1;59-68

  • Genetic analysis of KRAS mutation status in metastatic colorectal cancer patients.

    Zavodna K, Konecny M, Krivulcik T, Spanik S, Behulova R, Vizvaryova M, Weismanova E, Galbavy S and Kausitz J

    Department of Clinical Genetics, St.Elizabeth Cancer Institute, Bratislava, Slovak Republic. kzavodna@ousa.sk

    Colorectal carcinoma (CRC) represents a serious problem worldwide: in the Slovak republic are diagnosed about 2600 new CRC cases annually and its incidence is increasing. Colorectal cancer patients may succumb to the disease because of local recurrence or local formation of metastasis. Therefore, it is necessary to modulate therapeutic algorithm with new methods, leading to early diagnostic of CRC or changing the existing therapeutic procedures. Recent progresses have been made in understanding of EGFR pathway involved in CRC carcinogenesis, especially the role of Ras protein. Mutations in KRAS oncogene are frequently found in human cancers, particularly colorectal, pancreatic, billiary tract and lung tumors. The presence of the KRAS mutations in metastatic colorectal cancer patients correlates with lack of response to the certain epidemal growth factor receptor (EGFR) inhibitor therapies, such as Panitumumab and Cetuximab. Consequently, screening for KRAS mutations status may be used as a prognostic marker, because the CRC patients with KRAS positive tumors have a worse prognosis. The aim of our study was to establish the methods for rapid and sensitive detection of KRAS mutation status in formalin fixed paraffin embedded (FFPE) tissues DNA. We applied Real Time PCR analysis (TheraScreen KRAS Mutation Test Kit) and sequencing analysis (optimised for the analysis of FFPE tissues) to detect somatic mutations in codon 12 and 13 of KRAS gene. Both methods were used concurrently in the panel of DNA isolated from 25 colorectal FFPE tissues tumor. The positive or negative results from all 25 samples were identified by both methods independently. The KRAS mutations were presented in 8 of 25 patients (32%). Our results demonstrate that the Real Time PCR analysis can be used for detection of somatic KRAS mutations in FFPE clinical samples. However, we also recognize that the sequencing analysis of approximately 200bp amplicons may be used for mutations status screening, but with care of method sensitivity.

    Neoplasma 2009;56;3;275-8

  • KRAS mutation analysis in ovarian samples using a high sensitivity biochip assay.

    Auner V, Kriegshäuser G, Tong D, Horvat R, Reinthaller A, Mustea A and Zeillinger R

    Division of Gynaecology, Department of Obstetrics and Gynaecology, Medical University of Vienna, Vienna, Austria. veronika.auner@meduniwien.ac.at

    Background: Mutations in the KRAS gene are one of the most frequent genetic abnormalities in ovarian carcinoma. They are of renewed interest as new epidermal growth factor receptor (EGFR)-targeted therapies are being investigated for use in ovarian carcinoma. As KRAS mutations are associated with poor response and resistance to EGFR-targeting drugs, this study was conducted to obtain more information on the spectrum of KRAS mutations in ovarian carcinoma.

    Methods: The presence of KRAS mutations in codon 12 and 13 was analyzed in frozen and formalin-fixed paraffin-embedded (FFPE) tissue with a low density biochip platform. 381 malignant (29 borderline malignancy, 270 primary carcinomas, and 82 recurrent carcinomas) and 22 benign tissue samples from a total of 394 patients were examined. KRAS mutational status of each sample was correlated with dignity, FIGO stage, grade, histology, and survival.

    Results: KRAS mutations were found in 60 (15%) samples with 58 samples deriving from malignant tissue and 2 samples deriving from benign tissue. In 55 (92%) samples codon 12 was found to be mutated. Frozen and FFPE samples concurred with respect to KRAS mutation status.

    Conclusion: KRAS mutation is a common event in ovarian cancer primarily in carcinomas of lower grade, lower FIGO stage, and mucinous histotype. The KRAS mutational status is no prognostic factor for patients treated with standard therapy. However, in line with experience from colorectal cancer and non-small-cell-lung cancer (NSCLC), it may be important for prediction of response to EGFR-targeted therapies.

    BMC cancer 2009;9;111

  • KRAS mutations in primary colorectal cancer tumors and related metastases: a potential role in prediction of lung metastasis.

    Cejas P, López-Gómez M, Aguayo C, Madero R, de Castro Carpeño J, Belda-Iniesta C, Barriuso J, Moreno García V, Larrauri J, López R, Casado E, Gonzalez-Barón M and Feliu J

    Department of Medical Oncology, La Paz University Hospital, Madrid, Spain.

    Background: KRAS mutations in colorectal cancer primary tumors predict resistance to anti-Epidermal Growth Factor Receptor (EGFR) monoclonal antibody therapy in patients with metastatic colorectal cancer, and thus represent a true indicator of EGFR pathway activation status.

    KRAS mutations were retrospectively studied using polymerase chain reactions and subsequent sequencing of codons 12 and 13 (exon 2) in 110 patients with metastatic colorectal tumors. These studies were performed using tissue samples from both the primary tumor and their related metastases (93 liver, 84%; 17 lung, 16%). All patients received adjuvant 5-Fluorouracil-based polychemotherapy after resection of metastases. None received anti-EGFR therapy. Mutations in KRAS were observed in 37 (34%) of primary tumors and in 40 (36%) of related metastases, yielding a 94% level of concordance (kappa index 0.86). Patients with primary tumors possessing KRAS mutations had a shorter disease-free survival period after metastasis resection (12.0 vs 18.0 months; P = 0.035) than those who did not. A higher percentage of KRAS mutations was detected in primary tumors of patiens with lung metastases than in patients with liver metastases (59% vs 32%; p = 0.054). To further evaluate this finding we analyzed 120 additional patients with unresectable metastatic colorectal cancer who previously had their primary tumors evaluated for KRAS mutational status for clinical purposes. Separately, the analysis of these 120 patients showed a tendency towards a higher degree of KRAS mutations in primary tumors of patients with lung metastases, although it did not reach statistical significance. Taken together the group of 230 patients showed that KRAS was mutated significantly more often in the primary tumors of patients with lung metastases (57% vs 35%; P = 0.006).

    Our results suggest a role for KRAS mutations in the propensity of primary colorectal tumors to metastasize to the lung.

    PloS one 2009;4;12;e8199

  • Mutations in the KRAS gene in ovarian tumors.

    Dobrzycka B, Terlikowski SJ, Kowalczuk O, Niklińska W, Chyczewski L and Kulikowski M

    Department of Gynecological and Obstetrical Nursing, Medical University of Białystok, Poland. bdobrzycka@gmail.com

    RAS genes are the most frequently mutated oncogenes detected in human cancer. In this study we analyzed the presence of mutations at codon 12 of the KRAS gene in 78 women with ovarian tumor, including 64 invasive ovarian cancers and 14 borderline ovarian tumors, using an RFLP-PCR technique and we evaluated whether such alterations were associated with the selected clinicopathological parameters of the patients. KRAS codon 12 gene mutations were found in 6,2% of ovarian cancer tissue and in 14,3% of the borderline ovarian tumor. KRAS mutations were found with a significantly higher frequency in mucinous and borderline tumors compared to serous tumors (p<0,01). Mutation frequency was correlated with the histological type of tumor, but not with stage, grade or patients age.

    Folia histochemica et cytobiologica 2009;47;2;221-4

  • Mutations of the KRAS oncogene in endometrial hyperplasia and carcinoma.

    Dobrzycka B, Terlikowski SJ, Mazurek A, Kowalczuk O, Niklińska W, Chyczewski L and Kulikowski M

    Department of Gynecological and Obstetrical Nursing, Medical University of Białystok, Białystok, Poland. bdobrzycka@gmail.com

    The aim of this study was to examine the prevalence and clinicopathological significance of KRAS point mutation in endometrial hyperplasia and carcinoma. We analysed KRAS in 11 cases of complex atypical hyperplasia and in 49 endometrial carcinomas using polymerase chain reaction associated with restriction fragment length polymorphism (PCR-RFPL). Point mutations at codon 12 of KRAS oncogene were identified in 7 of 49 (14,3%) tumor specimens and in 2 of 11 (18,2%) hyperplasias. No correlation was found between KRAS gene mutation and age at onset, histology, grade of differentiation and clinical stage. We conclude that KRAS mutation is a relatively common event in endometrial carcinogenesis, but with no prognostic value.

    Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society 2009;47;1;65-8

  • Oncogene mutations, copy number gains and mutant allele specific imbalance (MASI) frequently occur together in tumor cells.

    Soh J, Okumura N, Lockwood WW, Yamamoto H, Shigematsu H, Zhang W, Chari R, Shames DS, Tang X, MacAulay C, Varella-Garcia M, Vooder T, Wistuba II, Lam S, Brekken R, Toyooka S, Minna JD, Lam WL and Gazdar AF

    Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America.

    Background: Activating mutations in one allele of an oncogene (heterozygous mutations) are widely believed to be sufficient for tumorigenesis. However, mutant allele specific imbalance (MASI) has been observed in tumors and cell lines harboring mutations of oncogenes.

    We determined 1) mutational status, 2) copy number gains (CNGs) and 3) relative ratio between mutant and wild type alleles of KRAS, BRAF, PIK3CA and EGFR genes by direct sequencing and quantitative PCR assay in over 400 human tumors, cell lines, and xenografts of lung, colorectal, and pancreatic cancers. Examination of a public database indicated that homozygous mutations of five oncogenes were frequent (20%) in 833 cell lines of 12 tumor types. Our data indicated two major forms of MASI: 1) MASI with CNG, either complete or partial; and 2) MASI without CNG (uniparental disomy; UPD), due to complete loss of wild type allele. MASI was a frequent event in mutant EGFR (75%) and was due mainly to CNGs, while MASI, also frequent in mutant KRAS (58%), was mainly due to UPD. Mutant: wild type allelic ratios at the genomic level were precisely maintained after transcription. KRAS mutations or CNGs were significantly associated with increased ras GTPase activity, as measured by ELISA, and the two molecular changes were synergistic. Of 237 lung adenocarcinoma tumors, the small number with both KRAS mutation and CNG were associated with shortened survival.

    Conclusions: MASI is frequently present in mutant EGFR and KRAS tumor cells, and is associated with increased mutant allele transcription and gene activity. The frequent finding of mutations, CNGs and MASI occurring together in tumor cells indicates that these three genetic alterations, acting together, may have a greater role in the development or maintenance of the malignant phenotype than any individual alteration.

    Funded by: NCI NIH HHS: P50CA70907, U01CA084971

    PloS one 2009;4;10;e7464

  • KRAS or BRAF mutation status is a useful predictor of sensitivity to MEK inhibition in ovarian cancer.

    Nakayama N, Nakayama K, Yeasmin S, Ishibashi M, Katagiri A, Iida K, Fukumoto M and Miyazaki K

    Departments of Obstetrics and Gynecology, Shimane University School of Medicine, Izumo, Japan.

    This study examined the status of KRAS and BRAF mutations, in relation to extracellular signal-regulated protein kinase (ERK) activation in 58 ovarian carcinomas to clarify the clinicopathological and prognostic significance of KRAS/BRAF mutations. Somatic mutations of either KRAS or BRAF were identified in 12 (20.6%) out of 58 ovarian carcinomas. The frequency of KRAS/BRAF mutations in conventional serous high-grade carcinomas (4.0% : 1/25) was significantly lower than that in the other histological type (32.3% : 10/31). Phosphorylated ERK1/2 (p-ERK1/2) expression was identified in 18 (38.2%) out of 45 ovarian carcinomas. KRAS/BRAF mutation was significantly correlated with International Federation of Gynecology and Obstetrics (FIGO) stage I, II (P<0.001), and p-ERK1/2 (P<0.001). No significant correlations between KRAS/BRAF mutations or p-ERK1/2 expression and overall survival were found in patients with ovarian carcinoma treated with platinum and taxane chemotherapy (P=0.2460, P=0.9339, respectively). Next, to clarify the roles of ERK1/2 activation in ovarian cancers harbouring KRAS or BRAF mutations, we inactivated ERK1/2 in ovarian cancer cells using CI-1040. Cl-1040 is a compound that selectively inhibits MAP kinase kinase (MEK), an upstream regulator of ERK1/2, and thus prevents ERK1/2 activation. Profound growth inhibition and apoptosis were observed in CI-1040-treated cancer cells with mutations in either KRAS or BRAF in comparison with the ovarian cancer cells containing wild-type sequences. This was evident in both in vitro and in vivo studies. The findings in this study indicate that an activated ERK1/2 pathway is critical to tumour growth and survival of ovarian cancers with KRAS or BRAF mutations. Furthermore, they suggest that the CI-1040-induced phenotypes depend on the mutational status of KRAS and BRAF in ovarian cancers. Therefore, ovarian cancer patients with KRAS or BRAF mutations may benefit from CI-1040 treatment.

    British journal of cancer 2008;99;12;2020-8

  • Wild-type BRAF is required for response to panitumumab or cetuximab in metastatic colorectal cancer.

    Di Nicolantonio F, Martini M, Molinari F, Sartore-Bianchi A, Arena S, Saletti P, De Dosso S, Mazzucchelli L, Frattini M, Siena S and Bardelli A

    Laboratory of Molecular Genetics, The Oncogenomics Center, Institute for Cancer Research and Treatment, University of Torino, Medical School, Candiolo, Torino, Italy.

    PURPOSE Cetuximab or panitumumab are effective in 10% to 20% unselected metastatic colorectal cancer (CRC) patients. KRAS mutations account for approximately 30% to 40% patients who are not responsive. The serine-threonine kinase BRAF is the principal effector of KRAS. We hypothesized that, in KRAS wild-type patients, BRAF mutations could have a predictive/prognostic value. PATIENTS AND METHODS We retrospectively analyzed objective tumor responses, time to progression, overall survival (OS), and the mutational status of KRAS and BRAF in 113 tumors from cetuximab- or panitumumab-treated metastatic CRC patients. The effect of the BRAF V600E mutation on cetuximab or panitumumab response was also assessed using cellular models of CRC. Results KRAS mutations were present in 30% of the patients and were associated with resistance to cetuximab or panitumumab (P = .011). The BRAF V600E mutation was detected in 11 of 79 patients who had wild-type KRAS. None of the BRAF-mutated patients responded to treatment, whereas none of the responders carried BRAF mutations (P = .029). BRAF-mutated patients had significantly shorter progression-free survival (P = .011) and OS (P < .0001) than wild-type patients. In CRC cells, the introduction of BRAF V600E allele impaired the therapeutic effect of cetuximab or panitumumab. Treatment with the BRAF inhibitor sorafenib restored sensitivity to panitumumab or cetuximab of CRC cells carrying the V600E allele. CONCLUSION BRAF wild-type is required for response to panitumumab or cetuximab and could be used to select patients who are eligible for the treatment. Double-hit therapies aimed at simultaneous inhibition of epidermal growth factor receptor and BRAF warrant exploration in CRC patients carrying the V600E oncogenic mutation.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2008;26;35;5705-12

  • Polymorphisms in cyclooxygenase-2 and epidermal growth factor receptor are associated with progression-free survival independent of K-ras in metastatic colorectal cancer patients treated with single-agent cetuximab.

    Lurje G, Nagashima F, Zhang W, Yang D, Chang HM, Gordon MA, El-Khoueiry A, Husain H, Wilson PM, Ladner RD, Mauro DJ, Langer C, Rowinsky EK and Lenz HJ

    Division of Medical Oncology, University of Southern California/Norris Comprehensive Cancer Center, Keck School of Medicine, Los Angeles, California 90033, USA.

    Purpose: Recently, an objective response rate of 12% was reported in a phase II study of cetuximab in patients with epidermal growth factor receptor (EGFR)-expressing metastatic colorectal cancer (mCRC) refractory to fluoropyrimidine-, oxaliplatin-, and irinotecan-based chemotherapy (IMC-0144). In this large molecular correlates study, we tested whether K-ras mutation status and polymorphisms in genes involved in the EGFR-signaling pathway were associated with clinical outcome in IMC-0144.

    We analyzed all available tissue samples from 130 of 346 mCRC patients enrolled in the IMC-0144 phase II clinical trial of cetuximab. Genomic DNA was extracted from formalin-fixed paraffin-embedded tumor tissues, and K-ras mutation status and the genotypes were analyzed using PCR-RFLP, direct DNA-sequencing, and 5'-end [gamma-33P] ATP-labeled PCR-protocols.

    Results: The PFS of patients with cyclooxygenase-2 (COX-2) -765 G>C [C/C; risk ratio (RR), 0.31; 95% confidence interval (95% CI), 0.12-0.84; P = 0.032], COX-2 +8473 T>C (C/C; RR, 0.67; 95% CI, 0.40-1.13; P = 0.003), EGF +61 A>G (G/G; RR, 0.57; 95% CI, 0.34-0.95; P = 0.042), and EGFR +497 G>A (A/G; RR, 0.82; 95% CI, 0.56-1.20; P = 0.017) genotypes was significantly longer compared with those with other genotypes. In addition, patients whose tumors did not have K-ras mutations showed better RR, PFS, and overall survival than patients with K-ras mutations. In multivariable analysis, COX-2 +8473 T>C (adjusted P = 0.013) and EGFR +497 G>A (adjusted P = 0.010) remained significantly associated with progression-free survival, independent of skin rash toxicity, K-ras mutation status, and Eastern Cooperative Group performance status.

    Conclusions: Polymorphisms in COX-2 and EGFR may be useful independent molecular markers to predict clinical outcome in patients with mCRC treated with single-agent cetuximab, independent of skin rash toxicity, K-ras mutation, and Eastern Cooperative Oncology Group performance status.

    Funded by: NCI NIH HHS: 5 P30CA14089-271

    Clinical cancer research : an official journal of the American Association for Cancer Research 2008;14;23;7884-95

  • Reversed mutation rates of KRAS and EGFR genes in adenocarcinoma of the lung in Taiwan and their implications.

    Wu CC, Hsu HY, Liu HP, Chang JW, Chen YT, Hsieh WY, Hsieh JJ, Hsieh MS, Chen YR and Huang SF

    Department of Pathology, Chang Gung Memorial Hospital, Tao Yuan, Taiwan.

    Background: In western countries, the Kirsten ras oncogene homolog gene (KRAS) mutation rate is high in patients with nonsmall cell lung cancer (NSCLC), especially in those with adenocarcinoma (30%-50%), but the epidermal growth factor receptor gene (EGFR) mutation rate is very low (3%-8%). In addition, KRAS mutations reportedly were associated with EGFR tyrosine kinase inhibitor (EGFR-TKI) resistance. In Taiwan, high EGFR mutation rates associated with high EGFR-TKI response rates in patients with NSCLC have been reported; however, KRAS mutation data are limited and have not been correlated with TKI response.

    Methods: KRAS mutation analysis was performed on 237 NSCLC specimens, and the results were correlated with clinicopathologic features. All but 2 tumors also underwent EGFR mutation analysis.

    Results: KRAS mutations were identified in only 9 of 237 patients (3.80%). Five patients were women who were nonsmokers, and 4 patients were men who were ever-smokers. The mutation rate was 5.03% in patients with adenocarcinoma (8 of 159 patients) and 1.56% in patients with squamous cell carcinoma (1 of 64 patients). Four mutations were G12V, 3 mutations were G12D, 1 mutation was L19F, and 1 was the duplication insertion mutation dupT50_M72. In contrast, EGFR mutations were detected in 96 of 235 patients (40.8%) and in 90 of 157 adenocarcinomas (57.3%). None of the KRAS mutations coexisted with EGFR mutations. KRAS mutations were not associated significantly with any clinicopathologic characteristics, including smoking status. Among the 53 patients who had received TKI monotreatment, only 1 patient had a KRAS mutation and had progressive disease.

    Conclusions: The KRAS mutation rate was too low to play a significant role in TKI resistance or tumorigenesis among Taiwanese patients with NSCLC, which was the complete reverse of the results reported in western countries.

    Cancer 2008;113;11;3199-208

  • An activating KRAS mutation in imatinib-resistant chronic myeloid leukemia.

    Agarwal A, Eide CA, Harlow A, Corbin AS, Mauro MJ, Druker BJ, Corless CL, Heinrich MC and Deininger MW

    Funded by: NHLBI NIH HHS: HL082978-01

    Leukemia 2008;22;12;2269-72

  • Epidermal growth factor receptor-related tumor markers and clinical outcomes with erlotinib in non-small cell lung cancer: an analysis of patients from german centers in the TRUST study.

    Schneider CP, Heigener D, Schott-von-Römer K, Gütz S, Laack E, Digel W, Guschall WR, Franke A, Bodenstein H, Schmidtgen C and Reck M

    Department of Oncological Pneumology, Central Clinic Bad Berka, Bad Berka, Germany. cp.schneider.pne@zentralklinikbad-berka.de

    Introduction: Relationships between clinical outcomes and epidermal growth factor receptor (EGFR)-related tumor markers were investigated in patients with advanced non-small cell lung cancer.

    Methods: Patients with stage IIIB/IV non-small cell lung cancer (0-2 prior regimens) received erlotinib (150 mg PO per day). Response and survival were evaluated, and tumor samples were assessed by immunohistochemistry (EGFR, phosphorylated mitogen-activated protein kinase, and phosphorylated AKT protein expression), fluorescence in situ hybridization (FISH; EGFR gene copy number), and DNA sequencing (EGFR, KRAS gene mutations).

    Results: Among 311 patients, 8% had a complete/partial response; the disease control rate was 66%. Median Overall survival (OS) was 6.1 months; 1-year survival rate was 27.2%. Two of 4 patients with EGFR mutations had tumor responses, versus 2/68 with wild-type EGFR (p = 0.014). Progression-free survival (PFS) (HR = 0.31) and OS (HR = 0.33) were significantly prolonged in patients with EGFR mutations. Response rate was significantly higher in patients with EGFR FISH-positive (17%) than FISH-negative tumors (6%), and both PFS (HR = 0.58) and OS (HR = 0.63) significantly favored patients with EGFR FISH-positive tumors; median OS was 8.6 months in the EGFR FISH-positive group. None of 17 patients with a KRAS mutation had a tumor response, but the impact of KRAS mutation status on survival outcomes was of borderline statistical significance. Neither phosphorylated mitogen-activated protein kinase nor phosphorylated AKT immunohistochemistry status had a significant effect on PFS and OS with erlotinib.

    Conclusions: The presence of EGFR mutations and EGFR FISH-positive tumors may predispose patients to achieving better outcomes on erlotinib, but may have a beneficial impact on prognosis (irrespective of treatment). Prospective, placebo-controlled studies are needed to determine the predictive value of the putative biomarkers.

    Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer 2008;3;12;1446-53

  • Genetic and epigenetic alterations of familial pancreatic cancers.

    Brune K, Hong SM, Li A, Yachida S, Abe T, Griffith M, Yang D, Omura N, Eshleman J, Canto M, Schulick R, Klein AP, Hruban RH, Iacobuzio-Donohue C and Goggins M

    Department of Pathology, Medicine, Oncology, Johns Hopkins Medical Institutions, The Sol Goldman Pancreatic Cancer Research Center, 1550 Orleans Street, CRB2, Room 342, Baltimore, MD 21231, USA.

    Background: Little is known about the genetic and epigenetic changes that contribute to familial pancreatic cancers. The aim of this study was to compare the prevalence of common genetic and epigenetic alterations in sporadic and familial pancreatic ductal adenocarcinomas.

    Methods: DNA was isolated from the microdissected cancers of 39 patients with familial and 36 patients with sporadic pancreatic adenocarcinoma. KRAS2 mutations were detected by BstN1 digestion and/or cycle sequencing. TP53 and SMAD4 status were determined by immunohistochemistry on tissue microarrays of 23 archival familial pancreatic adenocarcinomas and in selected cases by cycle sequencing to identify TP53 gene mutations. Methylation-specific PCR analysis of seven genes (FoxE1, NPTX2, CLDN5, P16, TFPI-2, SPARC, ppENK) was done on a subset of fresh-frozen familial pancreatic adenocarcinomas.

    Results: KRAS2 mutations were identified in 31 of 39 (80%) of the familial versus 28 of 36 (78%) of the sporadic pancreatic cancers. Positive immunolabeling for p53 was observed in 57% of the familial pancreatic cancers and loss of SMAD4 labeling was observed in 61% of the familial pancreatic cancers, rates similar to those observed in sporadic pancreatic cancers. The mean prevalence of aberrant methylation in the familial pancreatic cancers was 68.4%, which was not significantly different from that observed in sporadic pancreatic cancers.

    Conclusion: The prevalence of mutant KRAS2, inactivation of TP53 and SMAD4, and aberrant DNA methylation of a seven-gene panel is similar in familial pancreatic adenocarcinomas as in sporadic pancreatic adenocarcinomas. These findings support the use of markers of sporadic pancreatic adenocarcinomas to detect familial pancreatic adenocarcinomas.

    Funded by: NCI NIH HHS: P50 CA062924, P50 CA062924-130011, P50 CA062924-140011, P50CA62924, R01 CA120432, R01CA120432

    Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 2008;17;12;3536-42

  • High concordance of KRAS status between primary colorectal tumors and related metastatic sites: implications for clinical practice.

    Santini D, Loupakis F, Vincenzi B, Floriani I, Stasi I, Canestrari E, Rulli E, Maltese PE, Andreoni F, Masi G, Graziano F, Baldi GG, Salvatore L, Russo A, Perrone G, Tommasino MR, Magnani M, Falcone A, Tonini G and Ruzzo A

    Department of Oncology, University Campus Bio-Medico, Rome, Italy. d.santini@unicampus.it

    Purpose: Several studies have suggested that KRAS somatic mutations may predict resistance to cetuximab- and panitumumab-based treatments in metastatic colorectal cancer (CRC) patients. Nevertheless, most experiences were conducted on samples from primaries. The aim of this study was to evaluate the grade of concordance in terms of KRAS status between primaries and related metastases.

    We analyzed KRAS codon 12 and 13 mutations from formalin-fixed sections of 107 CRC primaries and related metastases. Eight pairs were excluded from the analysis because of the low amount of tumor tissue in the available samples. The main characteristics were: 50 men, 49 women; median age at diagnosis, 71 years (range, 41-84). The metastatic sites analyzed were the liver in 80 patients (80.8%), lung in seven patients (7.1%), and other sites in 12 patients (12.1%).

    Results: A KRAS mutation was found in 38 (38.4%) primary tumors and in 36 (36.4%) related metastases. The rate of concordance was 96.0% (95% confidence interval, 90.0%-98.9%). Discordance was observed in only four (4%) patients.

    Conclusions: Our results indicate that the detection of KRAS mutations in either primary or metastatic tumors from patients with CRC is concordant and this assessment could be used to predict response to targeted therapies such as cetuximab and panitumumab.

    The oncologist 2008;13;12;1270-5

  • Hyperplastic polyps and sessile serrated adenomas as a phenotypic expression of MYH-associated polyposis.

    Boparai KS, Dekker E, Van Eeden S, Polak MM, Bartelsman JF, Mathus-Vliegen EM, Keller JJ and van Noesel CJ

    Department of Gastroenterology & Hepatology, Academic Medical Center, Amsterdam, The Netherlands.

    MYH-associated polyposis (MAP) is a disorder caused by a bi-allelic germline MYH mutation, characterized by multiple colorectal adenomas. These adenomas typically harbor G:C-->T:A transversions in the APC and K-ras genes caused by MYH deficiency. Occasional hyperplastic polyps (HPs) have been described in MAP patients but a causal relationship has never been investigated. We examined the presence of HPs and sessile serrated adenomas (SSAs) in 17 MAP patients and studied the occurrence of G:C-->T:A transversions in the APC and K-ras gene in these polyps.

    Methods: MAP patients were analyzed for the presence of HPs/SSAs. APC-mutation cluster region and K-ras codon 12 mutation analysis was performed in adenomas (n = 22), HPs (n = 63), and SSAs (n = 10) from these patients and from a control group of sporadic adenomas (n = 17), HPs (n = 24), and SSAs (n = 17).

    Results: HPs/SSAs were detected in 8 of 17 (47%) MAP patients, of whom 3 (18%) met the criteria for hyperplastic polyposis syndrome. APC mutations were detected only in adenomas and comprised exclusively G:C-->T:A transversions. K-ras mutations were detected in 51 of 73 (70%) HPs/SSAs in MAP patients, compared with 7 of 41 (17%) sporadic HPs/SSAs in the control group (P < .0001). In HPs/SSAs, 48 of 51 (94%) K-ras mutations showed G:C-->T:A transversions, compared with 2 of 7 (29%) sporadic HPs/SSAs in the control group (P < .0001).

    Conclusions: HPs and SSAs are a common finding in MAP patients. The detection of almost exclusively G:C-->T:A transversions in the K-ras gene of HPs/SSAs strongly suggests that these polyps are related causally to MYH deficiency. This implies that distinct pathways, that is, APC-gene related in adenomas and nonrelated in HPS/SSAs, appear to be operational in MAP.

    Gastroenterology 2008;135;6;2014-8

  • KRAS mutation in metastatic colorectal cancer and its impact on the use of EGFR inhibitors.

    Lenz HJ, Chu E and Grothey A

    Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.

    As with many malignancies, cytogenetic information has become increasingly important to the diagnosis and proper treatment of colorectal cancer. In particular, several recent studies have confirmed that KRAS is not only one of the most commonly mutated genes in colorectal cancer, but also essential to treatment decision-making. Several key studies have demonstrated that patients with mutant KRAS do not respond to treatment with epidermal growth factor inhibitors. This finding has several implications for clinicians who treat patients with metastatic colorectal cancer. The following monograph includes discussions on the key issues surrounding the integration of recent data on KRAS status into the care of patients with this disease.

    Clinical advances in hematology & oncology : H&O 2008;6;12;1-13, 14-6

  • Exclusive KRAS mutation in microsatellite-unstable human colorectal carcinomas with sequence alterations in the DNA mismatch repair gene, MLH1.

    Zhao Y, Miyashita K, Ando T, Kakeji Y, Yamanaka T, Taguchi K, Ushijima T, Oda S and Maehara Y

    Institute for Clinical Research, National Kyushu Cancer Center, 3-1-1, Notame, Fukuoka 811-1395, Japan.

    Microsatellite instability (MSI) is regarded as reflecting defective DNA mismatch repair (MMR). MMR defects lead to an increase in point mutations, as well as repeat instability, on the genome. However, despite the highly unstable microsatellites, base substitutions in representative oncogenes or tumor suppressors are extremely infrequent in MSI-positive tumors. Recently, the heterogeneity in MSI-positive colorectal tumors is pointed out, and the 'hereditary' and 'sporadic settings' are proposed. Particularly in the former, base substitution mutations in KRAS are regarded as relatively frequent. We sequenced the KRAS gene in a panel of 76 human colorectal carcinomas in which the MSI status has been determined. KRAS mutations were detected in 22 tumors (28.9%). Intriguingly, all of the KRAS-mutant MSI-H (high) tumors harbored sequence alterations in an essential MMR gene, MLH1, which implies that KRAS mutation more frequently and almost exclusively occurs in MMR gene-mutant MSI-H tumors. Furthermore, in contrast with the prevailing viewpoint, some of these tumors are derived from sporadic colorectal cancer patients. The tight connection between MMR gene mutation and KRAS mutation may suggest previously unrecognized complexities in the relationship between MSI and the mutator phenotype derived from defective MMR.

    Gene 2008;423;2;188-93

  • KRAS mutational testing in the selection of patients for EGFR-targeted therapies.

    Garcia J, Riely GJ, Nafa K and Ladanyi M

    Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA.

    The small-molecule epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors and the anti-EGFR monoclonal antibodies have proven activity in lung and colorectal adenocarcinomas, respectively, but only a small fraction of patients exhibit significant responses. The observation that only a minority of patients respond to EGFR-targeted therapies, in combination with their toxicity and high costs, has driven the search for molecular markers predictive of response. The main focus of the present review is the recent discovery that mutations in the KRAS oncogene constitute a negative predictive marker in this clinical setting, namely that their presence can be used to predict which patients are unlikely to benefit from treatment with EGFR-directed therapy.

    Seminars in diagnostic pathology 2008;25;4;288-94

  • Mutual exclusiveness between PIK3CA and KRAS mutations in endometrial carcinoma.

    Kang S, Seo SS, Chang HJ, Yoo CW, Park SY and Dong SM

    Research Institute and Hospital, National Cancer Center, Goyang, Gyeonggi, Korea.

    In endometrial carcinomas (ECs), previous report suggested that PIK3CA mutations do not coexist with KRAS mutations, but the significant mutual exclusiveness has not been demonstrated. In this study, we examined the mutation frequency of PIK3CA in EC and its mutual exclusiveness with KRAS mutation. We performed mutational analysis of PIK3CA through a polymerase chain reaction single-strand conformation polymorphism assay in 44 cases of endometrial cancer and analyzed the correlation with loss of PTEN, KRAS mutation, and RASSF1A hypermethylation. Somatic mutations of PIK3CA were detected in 14 of 44 (31.8%) of endometrial cancers. In exon 9, seven PIK3CA mutations were located, while seven mutations were located in exon 20. The most common mutation was E545A (35.7%), followed by H1047R (28.6%). Concomitant loss of PTEN expression and PIK3CA mutation was found in four cases of endometrial cancer. KRAS mutations were mutually exclusive with PIK3CA mutations, and those mutations were inversely correlated with statistical significance (P = 0.039). Also, we found that mutations in ERBB2 were mutually exclusive with PIK3CA mutations. RASSF1A and hMLH1 methylation were not correlated with the presence of PIK3CA mutations. PIK3CA was frequently mutated in endometrial cancers. KRAS and PIK3CA mutations are inversely correlated, suggesting that genetic alterations of KRAS and PIK3CA may play equivalent roles in endometrial carcinogenesis.

    International journal of gynecological cancer : official journal of the International Gynecological Cancer Society 2008;18;6;1339-43

  • Rapid screening assay for KRAS mutations by the modified smart amplification process.

    Tatsumi K, Mitani Y, Watanabe J, Takakura H, Hoshi K, Kawai Y, Kikuchi T, Kogo Y, Oguchi-Katayama A, Tomaru Y, Kanamori H, Baba M, Ishidao T, Usui K, Itoh M, Cizdziel PE, Lezhava A, Ueda M, Ichikawa Y, Endo I, Togo S, Shimada H and Hayashizaki Y

    Genome Exploration Research Group (Genome Network Project Core Group), RIKEN Genomic Sciences Center, RIKEN Yokohama Institute, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, Japan. landy-tk@bd5.so-net.ne.jp

    Previously, the smart amplification process version 2 (SMAP-2) was developed to detect mutations from tissue and in crude cell lysates and has been used for rapid diagnosis of specific somatic mutations with single-nucleotide precision. The purpose of this study was to develop a rapid and practical method to detect cancer and metastasis in specimens using the SMAP-2 assay. We developed modified SMAP-2 assays that enabled detection of any change in a single codon using a single assay. Rapid SMAP-2 screening assays are suitable for routine clinical identification of critical amino acid substitutions such as codon 12 mutations in KRAS. Primers bracketing the first two nucleotides of KRAS codon 12 were designed so that all possible alleles would be amplified by the SMAP-2 assay. In combination with the peptide nucleic acid (PNA) with exact homology to the wild-type allele, our assay amplified all mutant alleles except for the wild-type sequence. With this new assay design (termed PNA-clamp SMAP-2), we could detect KRAS mutations within 60 minutes, including sample preparation. We compared results from PNA-clamp SMAP-2 assay, polymerase chain reaction-restriction fragment length polymorphism, and direct sequencing of clinical samples from pancreatic cancer patients and demonstrated perfect concordance. The PNA-clamp SMAP-2 method is a rapid, simple, and highly sensitive detection assay for cancer mutations.

    The Journal of molecular diagnostics : JMD 2008;10;6;520-6

  • K-ras mutations and benefit from cetuximab in advanced colorectal cancer.

    Karapetis CS, Khambata-Ford S, Jonker DJ, O'Callaghan CJ, Tu D, Tebbutt NC, Simes RJ, Chalchal H, Shapiro JD, Robitaille S, Price TJ, Shepherd L, Au HJ, Langer C, Moore MJ and Zalcberg JR

    Flinders Medical Centre and Flinders University, Adelaide, Australia. c.karapetis@flinders.edu.au

    Background: Treatment with cetuximab, a monoclonal antibody directed against the epidermal growth factor receptor, improves overall and progression-free survival and preserves the quality of life in patients with colorectal cancer that has not responded to chemotherapy. The mutation status of the K-ras gene in the tumor may affect the response to cetuximab and have treatment-independent prognostic value.

    Methods: We analyzed tumor samples, obtained from 394 of 572 patients (68.9%) with colorectal cancer who were randomly assigned to receive cetuximab plus best supportive care or best supportive care alone, to look for activating mutations in exon 2 of the K-ras gene. We assessed whether the mutation status of the K-ras gene was associated with survival in the cetuximab and supportive-care groups.

    Results: Of the tumors evaluated for K-ras mutations, 42.3% had at least one mutation in exon 2 of the gene. The effectiveness of cetuximab was significantly associated with K-ras mutation status (P=0.01 and P<0.001 for the interaction of K-ras mutation status with overall survival and progression-free survival, respectively). In patients with wild-type K-ras tumors, treatment with cetuximab as compared with supportive care alone significantly improved overall survival (median, 9.5 vs. 4.8 months; hazard ratio for death, 0.55; 95% confidence interval [CI], 0.41 to 0.74; P<0.001) and progression-free survival (median, 3.7 months vs. 1.9 months; hazard ratio for progression or death, 0.40; 95% CI, 0.30 to 0.54; P<0.001). Among patients with mutated K-ras tumors, there was no significant difference between those who were treated with cetuximab and those who received supportive care alone with respect to overall survival (hazard ratio, 0.98; P=0.89) or progression-free survival (hazard ratio, 0.99; P=0.96). In the group of patients receiving best supportive care alone, the mutation status of the K-ras gene was not significantly associated with overall survival (hazard ratio for death, 1.01; P=0.97).

    Conclusions: Patients with a colorectal tumor bearing mutated K-ras did not benefit from cetuximab, whereas patients with a tumor bearing wild-type K-ras did benefit from cetuximab. The mutation status of the K-ras gene had no influence on survival among patients treated with best supportive care alone. (ClinicalTrials.gov number, NCT00079066.)

    The New England journal of medicine 2008;359;17;1757-65

  • A SNP in a let-7 microRNA complementary site in the KRAS 3' untranslated region increases non-small cell lung cancer risk.

    Chin LJ, Ratner E, Leng S, Zhai R, Nallur S, Babar I, Muller RU, Straka E, Su L, Burki EA, Crowell RE, Patel R, Kulkarni T, Homer R, Zelterman D, Kidd KK, Zhu Y, Christiani DC, Belinsky SA, Slack FJ and Weidhaas JB

    Department of Molecular, Yale University, New Haven, Connecticut 06520, USA.

    Lung cancer is the leading cause of cancer deaths worldwide, yet few genetic markers of lung cancer risk useful for screening exist. The let-7 family-of-microRNAs (miRNA) are global genetic regulators important in controlling lung cancer oncogene expression by binding to the 3' untranslated regions of their target mRNAs. The purpose of this study was to identify single nucleotide polymorphisms (SNP) that could modify let-7 binding and to assess the effect of such SNPs on target gene regulation and risk for non-small cell lung cancer (NSCLC). let-7 complementary sites (LCS) were sequenced in the KRAS 3' untranslated region from 74 NSCLC cases to identify mutations and SNPs that correlated with NSCLC. The allele frequency of a previously unidentified SNP at LCS6 was characterized in 2,433 people (representing 46 human populations). The frequency of the variant allele is 18.1% to 20.3% in NSCLC patients and 5.8% in world populations. The association between the SNP and the risk for NSCLC was defined in two independent case-control studies. A case-control study of lung cancer from New Mexico showed a 2.3-fold increased risk (confidence interval, 1.1-4.6; P = 0.02) for NSCLC cancer in patients who smoked <40 pack-years. This association was validated in a second independent case-control study. Functionally, the variant allele results in KRAS overexpression in vitro. The LCS6 variant allele in a KRAS miRANA complementary site is significantly associated with increased risk for NSCLC among moderate smokers and represents a new paradigm for let-7 miRNAs in lung cancer susceptibility.

    Funded by: NCI NIH HHS: CA074386, CA090578, CA092824, P20 CA090578, P50 CA090578, P50 CA090578-067601, R01 CA074386, R01 CA074386-10, R01 CA092824, R01 CA092824-06, R01 CA122676, R01 CA122676-02, U01 CA097356, U01 CA097356-05; NIEHS NIH HHS: ES00002, P30 ES000002

    Cancer research 2008;68;20;8535-40

  • K-RasG12D-induced T-cell lymphoblastic lymphoma/leukemias harbor Notch1 mutations and are sensitive to gamma-secretase inhibitors.

    Kindler T, Cornejo MG, Scholl C, Liu J, Leeman DS, Haydu JE, Fröhling S, Lee BH and Gilliland DG

    Division of Hematology, Department of Medicine, Brigham & Women's Hospital, Boston, MA, USA. thomas.kindler@ukmainz.de .

    To study the impact of oncogenic K-Ras on T-cell leukemia/lymphoma development and progression, we made use of a conditional K-Ras(G12D) murine knockin model, in which oncogenic K-Ras is expressed from its endogenous promoter. Transplantation of whole bone marrow cells that express oncogenic K-Ras into wild-type recipient mice resulted in a highly penetrant, aggressive T-cell leukemia/lymphoma. The lymphoblasts were composed of a CD4/CD8 double-positive population that aberrantly expressed CD44. Thymi of primary donor mice showed reduced cellularity, and immunophenotypic analysis demonstrated a block in differentiation at the double-negative 1 stage. With progression of disease, approximately 50% of mice acquired Notch1 mutations within the PEST domain. Of note, primary lymphoblasts were hypersensitive to gamma-secretase inhibitor treatment, which is known to impair Notch signaling. This inhibition was Notch-specific as assessed by down-regulation of Notch1 target genes and intracellular cleaved Notch. We also observed that the oncogenic K-Ras-induced T-cell disease was responsive to rapamycin and inhibitors of the RAS/MAPK pathway. These data indicate that patients with T-cell leukemia with K-Ras mutations may benefit from therapies that target the NOTCH pathway alone or in combination with inhibition of the PI3K/AKT/MTOR and RAS/MAPK pathways.

    Funded by: Howard Hughes Medical Institute; NCI NIH HHS: CA105423, CA66996, P01 CA066996, U01 CA105423

    Blood 2008;112;8;3373-82

  • A prospective study of dietary folate and vitamin B and colon cancer according to microsatellite instability and KRAS mutational status.

    Schernhammer ES, Giovannuccci E, Fuchs CS and Ogino S

    Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA. eva.schernhammer@channing.harvard.edu

    Sporadic microsatellite instability (MSI)-high colon cancers are positively associated with MLH1 promoter methylation and inversely with KRAS mutation. One-carbon metabolism is critical for methylation reactions and nucleotide biosynthesis, but the influence of dietary one-carbon nutrients such as folate and B vitamins on molecular changes in colon cancer is not known. Using the database of two independent prospective cohort studies (88,691 women and 47,371 men), we examined the relation between dietary intake of one-carbon nutrients and the incidence of microsatellite instability and KRAS mutation in 669 incident colon cancers. The overall inverse association between folate and colon cancer did not differ significantly according to MSI status [relative ratio (RR), 0.79; 95% confidence interval (95% CI), 0.60-1.03 for microsatellite stable/MSI-low colon cancers; and RR, 0.61, 95% CI, 0.37-1.02 for MSI-high colon cancers; P(heterogeneity)=0.53] or KRAS status (RR, 0.66; 95% CI, 0.49-0.87 for KRAS wild-type colon cancers; and RR, 1.05; 95% CI, 0.68-1.61 for KRAS mutated colon cancers; P(heterogeneity)=0.12), although our analyses had limited power to preclude an effect of folate on KRAS wild-type colon cancers. Similarly, high vitamin B(6) or B(12) intake was inversely associated with colon cancers, regardless of MSI or KRAS status. No significant effect of methionine intake or alcohol consumption was observed for colon cancers with MSI high or KRAS mutation. In conclusion, the influence of dietary one-carbon nutrient intake on colon cancer risk does not seem to differ according to MSI or KRAS mutational status.

    Funded by: NCI NIH HHS: CA122826, CA42812, CA55075, CA58684, CA70817, CA87969, CA90598, K07 CA122826-02, P01 CA055075-17, P01 CA087969-09, R01 CA042182-20, R01 CA058684-13, R01 CA070817, R01 CA070817-09, R01 CA090598-05S1

    Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 2008;17;10;2895-8

  • Assessment of somatic k-RAS mutations as a mechanism associated with resistance to EGFR-targeted agents: a systematic review and meta-analysis of studies in advanced non-small-cell lung cancer and metastatic colorectal cancer.

    Linardou H, Dahabreh IJ, Kanaloupiti D, Siannis F, Bafaloukos D, Kosmidis P, Papadimitriou CA and Murray S

    1st Department of Medical Oncology, Metropolitan Hospital, Athens, Greece.

    Background: Somatic mutations of the k-RAS oncogene have been assessed as a mechanism of de-novo resistance to epidermal growth factor receptor (EGFR) tyrosine-kinase inhibition in patients with non-small-cell lung cancer (NSCLC), and to anti-EGFR monoclonal antibodies in patients with metastatic colorectal cancer (mCRC). The aim of this systematic review and meta-analysis was to assess if k-RAS mutations represent a candidate predictive biomarker for anti-EGFR-targeted therapeutic strategies in mCRC and NSCLC.

    Methods: We systematically identified articles pertaining to k-RAS mutational status in patients with NSCLC treated with tyrosine-kinase inhibitors (TKI), and patients with mCRC treated with any anti-EGFR-based regimens. Eligible studies had to report complete responses (CR) and partial responses (PR), stratified by k-RAS mutational status. Potential between-study heterogeneity was accommodated by use of random-effects models for bivariable meta-analysis of sensitivity and specificity (the primary endpoints). The positive and negative likelihood ratios (+LR and -LR, respectively) of k-RAS mutations for predicting an absence of response were considered as secondary endpoints and were calculated by use of pooled estimates for sensitivity and specificity.

    Findings: Of 252 retrieved manuscripts, 17 were deemed eligible for the NSCLC meta-analysis (165 of 1008 patients with mutated k-RAS). The presence of k-RAS mutations was significantly associated with an absence of response to TKIs (sensitivity=0.21 [95% CI 0.16-0.28], specificity=0.94 [0.89-0.97]; +LR=3.52; -LR=0.84). Of 68 retrieved manuscripts reporting on anti-EGFR monoclonal-antibody-based treatment of mCRC, eight studies were deemed eligible for the final analysis (306 of 817 patients with mutated k-RAS). The presence of k-RAS mutations was significantly associated with an absence of response to anti-EGFR monoclonal-antibody-based treatments (sensitivity=0.47 [0.43-0.52]; specificity=0.93 [0.83-0.97]; +LR=6.82; -LR=0.57).

    Interpretation: This analysis provides empirical evidence that k-RAS mutations are highly specific negative predictors of response (de-novo resistance) to single-agent EGFR TKIs in advanced NSCLC; and similarly to anti-EGFR monoclonal antibodies alone or in combination with chemotherapy in patients with mCRC. The low sensitivity and relatively high -LR of k-RAS mutations for determining non-responsiveness clearly shows that additional mechanisms of resistance to EGFR inhibitors exist.

    The lancet oncology 2008;9;10;962-72

  • CpG island methylator phenotype in colorectal cancers: comparison of the new and classic CpG island methylator phenotype marker panels.

    Lee S, Cho NY, Yoo EJ, Kim JH and Kang GH

    Department of Pathology, Kyung Hee University College of Medicine, Seoul, Korea.

    Context: CpG island methylator phenotype (CIMP) designates a subset of colorectal cancers featuring concordant hypermethylation of multiple promoter CpG islands. Little is known about the clinical outcome or histologic characteristics of CIMP-positive colorectal cancers defined by recently identified CpG island methylator phenotype panels.

    Objective: To investigate and compare the molecular and clinicopathologic features of CIMP-positive colorectal cancers defined by classic (p16, hMLH1, MINT1, MINT2, MINT31) and new (CACNA1G, IGF2, NEUROG1, RUNX3, SOCS1) CIMP panels.

    Design: We analyzed 130 colorectal cancers for hypermethylation of both panels using methylation-specific polymerase chain reaction.

    Results: With at least 2 markers methylated, both classic (39/130; 23.1%) and new (23.1%) CIMP-positive colorectal cancers were significantly associated with proximal tumor location, microsatellite instability, and BRAF mutation (all P values were less than .05). The new panel outperformed the classic panel in detecting these features. With at least 3 markers methylated, new CIMP-positive colorectal cancers (16.9%) were closely associated with proximal tumor location, low frequency of KRAS mutation, and high frequency of BRAF mutation (all P values were less than .05), whereas classic CIMP-positive colorectal cancers (18.5%) were closely associated with proximal tumor location, frequent microsatellite instability, and frequent BRAF mutation (all P values were less than .05). Analyzing a combination of CIMP and microsatellite instability status, CIMP-positive/microsatellite instability-negative colorectal cancers had the worst clinical outcomes.

    Conclusions: Whereas the classic panel outperformed in predicting clinical outcome, the new panel was superior in detecting known clinicopathologic features of CIMP but inferior in prognostication power.

    Archives of pathology & laboratory medicine 2008;132;10;1657-65

  • Loss of heterozygosity predicts poor survival after resection of pancreatic adenocarcinoma.

    Franko J, Krasinskas AM, Nikiforova MN, Zarnescu NO, Lee KK, Hughes SJ, Bartlett DL, Zeh HJ and Moser AJ

    UPMC Pancreatic Cancer Center, Division of Surgical Oncology, 497 Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15261, USA.

    Background: American Joint Committee on Cancer (AJCC) staging for pancreatic adenocarcinoma is a validated predictor of prognosis but insufficiently discriminates postresection survival. We hypothesized that genetic analysis of resected cancers would correlate with tumor biology and postoperative survival.

    Methods: Resected pancreatic ductal and ampullary adenocarcinomas (n = 50) were analyzed for loss of heterozygosity (LOH) at 15 markers including 5q(APC), 6q(TBSP2), 9p(p16), 10q(PTEN), 12q(MDM2), 17p(TP53), and 18q(DCC/SMAD4). KRAS exon 1 mutations were detected by sequencing. The primary endpoint of this interim data analysis was survival at 18 month median follow-up.

    Results: Negative margins were achieved in 43 (86%) cases. AJCC stage was: Ia/b (3), IIa (16), IIb (31). KRAS mutations were detected in 31 cases (62%) and LOH in 26 (52%) with mean fractional allelic loss score 23 +/- 16%. Median survival was significantly shorter with LOH (15.2 months versus not reached; p = 0.021) and KRAS mutations (19.6 months versus not reached; p = 0.038). Combining KRAS mutation with LOH was a powerful negative predictor in Cox regression (HR = 10.6, p = 0.006). Stage, nodal and margin status were not predictive of survival.

    Conclusion: LOH and KRAS mutations indicate aggressive tumor biology and correlate strongly with survival in resected pancreatic ductal and ampullary carcinomas. Genetic analysis may improve risk stratification in future clinical trials.

    Journal of gastrointestinal surgery : official journal of the Society for Surgery of the Alimentary Tract 2008;12;10;1664-72; discussion 1672-3

  • Pathway-based evaluation of 380 candidate genes and lung cancer susceptibility suggests the importance of the cell cycle pathway.

    Hosgood HD, Menashe I, Shen M, Yeager M, Yuenger J, Rajaraman P, He X, Chatterjee N, Caporaso NE, Zhu Y, Chanock SJ, Zheng T and Lan Q

    Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA. hosgoodd@mail.nih.gov

    Common genetic variation may play an important role in altering lung cancer risk. We conducted a pathway-based candidate gene evaluation to identify genetic variations that may be associated with lung cancer in a population-based case-control study in Xuan Wei, China (122 cases and 111 controls). A total of 1260 single-nucleotide polymorphisms (SNPs) in 380 candidate genes for lung cancer were successfully genotyped and assigned to one of 10 pathways based on gene ontology. Logistic regression was used to assess the marginal effect of each SNP on lung cancer susceptibility. The minP test was used to identify statistically significant associations at the gene level. Important pathways were identified using a test of proportions and the rank truncated product methods. The cell cycle pathway was found as the most important pathway (P = 0.044) with four genes significantly associated with lung cancer (PLA2G6 minP = 0.001, CCNA2 minP = 0.006, GSK3 beta minP = 0.007 and EGF minP = 0.013), after adjusting for multiple comparisons. Interestingly, most cell cycle genes that were associated with lung cancer in this analysis were concentrated in the AKT signaling pathway, which is essential for regulation of cell cycle progression and cellular survival, and may be important in lung cancer etiology in Xuan Wei. These results should be viewed as exploratory until they are replicated in a larger study.

    Funded by: Intramural NIH HHS; NCI NIH HHS: TU2 CA105666

    Carcinogenesis 2008;29;10;1938-43

  • Comparison of EGFR and K-RAS gene status between primary tumours and corresponding metastases in NSCLC.

    Kalikaki A, Koutsopoulos A, Trypaki M, Souglakos J, Stathopoulos E, Georgoulias V, Mavroudis D and Voutsina A

    Laboratory of Tumor Cell Biology, School of Medicine, University of Crete, Heraklion, Crete, Greece.

    In non-small-cell lung cancer (NSCLC), epidermal growth factor receptor (EGFR) and K-RAS mutations of the primary tumour are associated with responsiveness and resistance to tyrosine kinase inhibitors (TKIs), respectively. However, the EGFR and K-RAS mutation status in metastases is not well studied. We compared the mutation status of these genes between the primary tumours and the corresponding metastases of 25 patients. Epidermal growth factor receptor and K-RAS mutation status was different between primary tumours and corresponding metastases in 7 (28%) and 6 (24%) of the 25 patients, respectively. Among the 25 primary tumours, three 'hotspot' and two non-classical EGFR mutations were found; none of the corresponding metastases had the same mutation pattern. Among the five (20%) K-RAS mutations detected in the primary tumours, two were maintained in the corresponding metastasis. Epidermal growth factor receptor and K-RAS mutations were detected in the metastatic tumours of three (12%) and five (20%) patients, respectively. The expressions of EGFR and phosphorylated EGFR showed I 0 and 50% discordance, in that order. We conclude that there is substantial discordance in EGFR and K-RAS mutational status between the primary tumours and corresponding metastases in patients with NSCLC and this might have therapeutic implications when treatment with TKIs is considered.

    British journal of cancer 2008;99;6;923-9

  • Comparisons of tyrosine phosphorylated proteins in cells expressing lung cancer-specific alleles of EGFR and KRAS.

    Guha U, Chaerkady R, Marimuthu A, Patterson AS, Kashyap MK, Harsha HC, Sato M, Bader JS, Lash AE, Minna JD, Pandey A and Varmus HE

    Program in Cancer Biology and Genetics, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA. guhau@mskcc.org

    We have used unbiased phosphoproteomic approaches, based on quantitative mass spectrometry using stable isotope labeling with amino acids in cell culture (SILAC), to identify tyrosine phosphorylated proteins in isogenic human bronchial epithelial cells (HBECs) and human lung adenocarcinoma cell lines, expressing either of the two mutant alleles of EGFR (L858R and Del E746-A750), or a mutant KRAS allele, which are common in human lung adenocarcinomas. Tyrosine phosphorylation of signaling molecules was greater in HBECs expressing the mutant EGFRs than in cells expressing WT EGFR or mutant KRAS. Receptor tyrosine kinases (such as EGFR, ERBB2, MET, and IGF1R), and Mig-6, an inhibitor of EGFR signaling, were more phosphorylated in HBECs expressing mutant EGFR than in cells expressing WT EGFR or mutant RAS. Phosphorylation of some proteins differed in the two EGFR mutant-expressing cells; for example, some cell junction proteins (beta-catenin, plakoglobin, and E-cadherin) were more phosphorylated in HBECs expressing L858R EGFR than in cells expressing Del EGFR. There were also differences in degree of phosphorylation at individual tyrosine sites within a protein; for example, a previously uncharacterized phosphorylation site in the nucleotide-binding loop of the kinase domains of EGFR (Y727), ERBB2 (Y735), or ERBB4 (Y733), is phosphorylated significantly more in HBECs expressing the deletion mutant than in cells expressing the wild type or L858R EGFR. Signaling molecules not previously implicated in ERBB signaling, such as polymerase transcript release factor (PTRF), were also phosphorylated in cells expressing mutant EGFR. Bayesian network analysis of these and other datasets revealed that PTRF might be a potentially important component of the ERBB signaling network.

    Funded by: NCI NIH HHS: P01 CA129243, P01 CA129243-01, P50 CA070907, P50CA70907; NCRR NIH HHS: U54 RR020839, US4RR020839

    Proceedings of the National Academy of Sciences of the United States of America 2008;105;37;14112-7

  • The effects of common genetic variants in oncogenes on ovarian cancer survival.

    Quaye L, Gayther SA, Ramus SJ, Di Cioccio RA, McGuire V, Hogdall E, Hogdall C, Blaakr J, Easton DF, Ponder BA, Jacobs I, Kjaer SK, Whittemore AS, Pearce CL, Pharoah PD and Song H

    Gynaecological Cancer Research Laboratory, UCL EGA Institute for Women's Health, University College London, London, United Kingdom.

    Purpose: The 5-year survival rate for invasive epithelial ovarian cancer is <35%. It has been suggested that common, germline genetic variation may influence survival after cancer diagnoses, which might enable the prediction of response to treatment and survival in the clinical setting. The aim of this study was to evaluate associations between common germline genetic variants in the oncogenes BRAF, ERBB2, KRAS, NMI, and PIK3CA, and survival after a diagnosis of epithelial ovarian cancer.

    We evaluated the association between 34 tagging single nucleotide polymorphisms and survival in 1,480 cases of invasive epithelial ovarian cancer cases from three different studies. Cox regression analysis, stratified by study, was used to estimate per rare allele hazard ratios (HR).

    Results: The minor allele rs6944385 in BRAF was significantly associated with poor survival [HR, 1.19; 95% confidence intervals (95% CI), 1.02-1.39; P = 0.024]. The association remained after adjusting for prognostic factors (adjusted HR, 1.20; 95 CI, 1.03-1.40; P = 0.018). A haplotype of BRAF was also associated with poor survival (HR, 1.24; 95% CI, 1.02-1.51; P = 0.029) and was more significant after adjustment (HR, 1.44; 95% CI, 1.15-1.81; P = 0.001). We also found evidence of an association between a KRAS haplotype and poor survival in serous subtype (HR, 1.69; 95% CI, 1.21-2.38; P = 0.002), but this was no longer significant after adjustment. Finally, when analyses were restricted to the serous histologic subtype, the rare allele rs10842513 in KRAS, was associated with poor survival (HR, 1.40; 95% CI, 1.10-1.78; P = 0.007).

    Conclusion: Common genetic variants in the BRAF and KRAS oncogenes may be important in the prediction of survival in patients with invasive epithelial ovarian cancer.

    Funded by: Cancer Research UK: C8804/A7058; Medical Research Council; NCI NIH HHS: CA16506, CA71766

    Clinical cancer research : an official journal of the American Association for Cancer Research 2008;14;18;5833-9

  • Clinical usefulness of EGFR gene copy number as a predictive marker in colorectal cancer patients treated with cetuximab: a fluorescent in situ hybridization study.

    Personeni N, Fieuws S, Piessevaux H, De Hertogh G, De Schutter J, Biesmans B, De Roock W, Capoen A, Debiec-Rychter M, Van Laethem JL, Peeters M, Humblet Y, Van Cutsem E and Tejpar S

    Digestive Oncology Unit, University Hospital Gasthuisberg, Leuven, Belgium.

    Purpose: To evaluate the usefulness and the pitfalls inherent to the assessment of the epidermal growth factor receptor (EGFR) gene copy number (GCN) by fluorescence in situ hybridization (FISH) for outcome prediction to cetuximab in metastatic colorectal cancer. The value of testing KRAS mutation status, in addition to EGFR GCN, was also explored.

    FISH analysis of 87 metastatic colorectal cancer patients treated with cetuximab was done, recording individual GCN per cell and using different samples per tumor. Performances of published cutoff points and different summaries of EGFR GCN distribution were assessed for response prediction.

    Results: In our data set, two published cutoff points performed less well than in their training set, yielding positive predictive values and negative predictive values between 40.0% and 48.3% and between 81.0% and 86.5%, respectively. Among summaries of GCN distribution explored, mean and right-tailed distribution of GCN yielded the highest performances. A mean EGFR GCN > or = 2.83 provided an area under the curve of 0.71. Important heterogeneity of repeated measures of mean EGFR GCN was observed within tumors (intraclass correlation, 0.61; within-class SD, 0.40), leading to potential misclassifications of FISH status in 7 of 18 (38.8%) patients if a cutoff point were used. In multivariable analysis, EGFR GCN testing provided significant information independent of the KRAS status to predict response (P = 0.016) and overall survival (P = 0.005).

    Conclusions: We confirm the association between increased EGFR GCN and outcome after cetuximab. However, because of reproducibility concerns, any decision making based on published cutoff points is not warranted.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2008;14;18;5869-76

  • Frequency and distinctive spectrum of KRAS mutations in never smokers with lung adenocarcinoma.

    Riely GJ, Kris MG, Rosenbaum D, Marks J, Li A, Chitale DA, Nafa K, Riedel ER, Hsu M, Pao W, Miller VA and Ladanyi M

    Thoracic Oncology Service, Division of Solid Tumor Oncology, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA. rielyg@mskcc.org

    Purpose: KRAS mutations are found in approximately 25% of lung adenocarcinomas in Western countries and, as a group, have been strongly associated with cigarette smoking. These mutations are predictive of poor prognosis in resected disease as well as resistance to treatment with erlotinib or gefitinib.

    We determined the frequency and type of KRAS codon 12 and 13 mutations and characterized their association with cigarette smoking history in patients with lung adenocarcinomas.

    Results: KRAS mutational analysis was done on 482 lung adenocarcinomas, 81 (17%) of which were obtained from patients who had never smoked cigarettes. KRAS mutations were found in 15% (12 of 81; 95% confidence intervals, 8-24%) of tumors from never smokers. Similarly, 22% (69 of 316; 95% confidence intervals, 17-27%) of tumors from former smokers, and 25% (21 of 85; 95% confidence intervals, 16-35%) of tumors from current smokers had KRAS mutations. The frequency of KRAS mutation was not associated with age, gender, or smoking history. The number of pack years of cigarette smoking did not predict an increased likelihood of KRAS mutations. Never smokers were significantly more likely than former or current smokers to have a transition mutation (G-->A) rather than the transversion mutations known to be smoking-related (G-->T or G-->C; P < 0.0001).

    Conclusions: Based on our data, KRAS mutations are not rare among never smokers with lung adenocarcinoma and such patients have a distinct KRAS mutation profile. The etiologic and biological heterogeneity of KRAS mutant lung adenocarcinomas is worthy of further study.

    Funded by: NCI NIH HHS: NIH P01 CA129243, P01 CA129243-01

    Clinical cancer research : an official journal of the American Association for Cancer Research 2008;14;18;5731-4

  • Role of KRAS and EGFR as biomarkers of response to erlotinib in National Cancer Institute of Canada Clinical Trials Group Study BR.21.

    Zhu CQ, da Cunha Santos G, Ding K, Sakurada A, Cutz JC, Liu N, Zhang T, Marrano P, Whitehead M, Squire JA, Kamel-Reid S, Seymour L, Shepherd FA, Tsao MS and National Cancer Institute of Canada Clinical Trials Group Study BR.21

    FRCPC, Princess Margaret Hospital, 610 University Ave, Toronto, Ontario, Canada M5G 2M9; Ming.Tsao@uhn.on.ca.

    Purpose: To evaluate the effect of KRAS and epidermal growth factor receptor (EGFR) genotype on the response to erlotinib treatment in the BR.21, placebo-controlled trial.

    We analyzed 206 tumors for KRAS mutation, 204 tumors for EGFR mutation, and 159 tumors for EGFR gene copy by fluorescent in situ hybridization (FISH). We reanalyzed EGFR deletion/mutation using two highly sensitive techniques that detect abnormalities in samples with 5% to 10% tumor cellularity. KRAS mutation was analyzed by direct sequencing.

    Results: Thirty patients (15%) had KRAS mutations, 34 (17%) had EGFR exon 19 deletion or exon 21 L858R mutations, and 61 (38%) had high EGFR gene copy (FISH positive). Response rates were 10% for wild-type and 5% for mutant KRAS (P = .69), 7% for wild-type and 27% for mutant EGFR (P = .03), and 5% for EGFR FISH-negative and 21% for FISH-positive patients (P = .02). Significant survival benefit from erlotinib therapy was observed for patients with wild-type KRAS (hazard ratio [HR] = 0.69, P = .03) and EGFR FISH positivity (HR = 0.43, P = .004) but not for patients with mutant KRAS (HR = 1.67, P = .31), wild-type EGFR (HR = 0.74, P = .09), mutant EGFR (HR = 0.55, P = .12), and EGFR FISH negativity (HR = 0.80, P = .35). In multivariate analysis, only EGFR FISH-positive status was prognostic for poorer survival (P = .025) and predictive of differential survival benefit from erlotinib (P = .005).

    Conclusion: EGFR mutations and high copy number are predictive of response to erlotinib. EGFR FISH is the strongest prognostic marker and a significant predictive marker of differential survival benefit from erlotinib.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2008;26;26;4268-75

  • BRAF, KRAS and PIK3CA mutations in colorectal serrated polyps and cancer: primary or secondary genetic events in colorectal carcinogenesis?

    Velho S, Moutinho C, Cirnes L, Albuquerque C, Hamelin R, Schmitt F, Carneiro F, Oliveira C and Seruca R

    Institute of Molecular Pathology and Immunology, University of Porto, Portugal. svelho@ipatimup.pt

    Background: BRAF, KRAS and PIK3CA mutations are frequently found in sporadic colorectal cancer (CRC). In contrast to KRAS and PIK3CA mutations, BRAF mutations are associated with tumours harbouring CpG Island methylation phenotype (CIMP), MLH1 methylation and microsatellite instability (MSI). We aimed at determine the frequency of KRAS, BRAF and PIK3CA mutations in the process of colorectal tumourigenesis using a series of colorectal polyps and carcinomas. In the series of polyps CIMP, MLH1 methylation and MSI were also studied.

    Methods: Mutation analyses were performed by PCR/sequencing. Bisulfite treated DNA was used to study CIMP and MLH1 methylation. MSI was detected by pentaplex PCR and Genescan analysis of quasimonomorphic mononucleotide repeats. Chi Square test and Fisher's Exact test were used to perform association studies.

    Results: KRAS, PIK3CA or BRAF occur in 71% of polyps and were mutually exclusive. KRAS mutations occur in 35% of polyps. PIK3CA was found in one of the polyps. V600E BRAF mutations occur in 29% of cases, all of them classified as serrated adenoma. CIMP phenotype occurred in 25% of the polyps and all were mutated for BRAF. MLH1 methylation was not detected and all the polyps were microsatellite stable. The comparison between the frequency of oncogenic mutations in polyps and CRC (MSI and MSS) lead us to demonstrate that KRAS and PIK3CA are likely to precede both types of CRC. BRAF mutations are likely to precede MSI carcinomas since the frequency found in serrated polyps is similar to what is found in MSI CRC (P = 0.9112), but statistically different from what is found in microsatellite stable (MSS) tumours (P = 0.0191).

    Conclusion: Our results show that BRAF, KRAS and PIK3CA mutations occur prior to malignant transformation demonstrating that these oncogenic alterations are primary genetic events in colorectal carcinogenesis. Further, we show that BRAF mutations occur in association with CIMP phenotype in colorectal serrated polyps and verified that colorectal serrated polyps and MSI CRC show a similar frequency of BRAF mutations. These results support that BRAF mutations harbour a mild oncogenic effect in comparison to KRAS and suggest that BRAF mutant colorectal cells need to accumulate extra epigenetic alterations in order to acquire full transformation and evolve to MSI CRC.

    BMC cancer 2008;8;255

  • Mutations of KRAS and BRAF in primary and matched metastatic sites of colorectal cancer.

    Artale S, Sartore-Bianchi A, Veronese SM, Gambi V, Sarnataro CS, Gambacorta M, Lauricella C and Siena S

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2008;26;25;4217-9

  • K-ras mutation, HPV infection and smoking or alcohol abuse positively correlate with esophageal squamous carcinoma.

    Lyronis ID, Baritaki S, Bizakis I, Krambovitis E and Spandidos DA

    Department of Virology, Medical School, University of Crete, Heraklion, Crete, Greece.

    The Ras/Raf/MEK/ERK (MAPK) signal transduction cascade is an important mediator of a number of cellular fates including growth, survival and apoptosis. The aim of this study was to determine the incidence of B-raf, Kirsten-ras (K-ras) and Neuroblastoma-ras (N-ras) gene mutations in esophageal squamous cell carcinoma (ESCC) in the Greek population. DNA was extracted from 30 ESCC and 32 normal esophageal specimens and screened for V600E B-raf, and K-ras/N-ras codon 12 mutations, by PCR-RFLP based analysis. Among the genes tested, only the heterozygous K-ras mutation was detected in 5 out of the 30 ESCC specimens (16%), whereas no mutation was found in the normal esophageal tissue (P < 0.022). The normal samples were screened negative for N-ras and V600E B-raf mutations. The increased risk of esophageal cancer was correlated with tobacco use (OR = 3.5, P < 0.023) and alcohol abuse (OR = 7.22, P < 0.001), accompanied with the high incidence of the k-ras codon 12 mutation (22%, OR = 1.77 and 21%, OR = 1.52), respectively. A similar positive association was seen in human papilloma virus (HPV)-infected patients (OR = 5.66, P < 0.003). Our overall findings demonstrate that the mutational activation of the K-ras gene, HPV infection and tobacco or alcohol abuse, can be considered independently or in combination as high risk factors for ESCC development.

    Pathology oncology research : POR 2008;14;3;267-73

  • Mutation of genes affecting the RAS pathway is common in childhood acute lymphoblastic leukemia.

    Case M, Matheson E, Minto L, Hassan R, Harrison CJ, Bown N, Bailey S, Vormoor J, Hall AG and Irving JA

    Northern Institute for Cancer Research, Newcastle upon Tyne, Tyne and Wear, United Kingdom.

    Deregulation of the RAS-RAF-mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)-ERK signaling cascade is often caused by somatic mutations in genes encoding proteins which influence the activity of this pathway and include NRAS, KRAS2, FLT3, PTPN11, and BRAF. We report the first comprehensive mutational screen of key exons of these genes in a large cohort of unselected acute lymphoblastic leukemia (ALL) cases at diagnosis (n = 86) and in a more selected cohort at disease recurrence (n = 47) using the sensitive method of denaturing high-performance liquid chromatography. We show that somatic mutations that deregulate the pathway constitute one of the most common genetic aberrations in childhood ALL (cALL), being found in 35% of diagnostic and 25% of relapse samples. In matched presentation/relapse pairs, mutations predominating at relapse could be shown to be present at very low levels at diagnosis using allele-specific PCR, thus implicating the mutated clone in disease progression. Importantly, in primary samples, we show that mutations are associated with activated ERK and differential cytotoxicity to MEK-ERK inhibitors was shown for some patients. Inhibitors of the pathway, which are currently undergoing clinical trial, may be a novel therapeutic option for cALL, particularly at relapse.

    Cancer research 2008;68;16;6803-9

  • K-Ras mutations and treatment outcome in colorectal cancer patients receiving exclusive fluoropyrimidine therapy.

    Etienne-Grimaldi MC, Formento JL, Francoual M, François E, Formento P, Renée N, Laurent-Puig P, Chazal M, Benchimol D, Delpero JR, Letoublon C, Pezet D, Seitz JF and Milano G

    Oncopharmacology Department, Centre Antoine Lacassagne, Université René Descartes, Paris, France.

    Purpose: K-Ras mutations predict resistance to anti-epidermal growth factor receptor (EGFR) monoclonal antibodies. Because combinations of anti-EGFR with 5-fluorouracil (5-FU)-based chemotherapy are promising treatments, we analyzed the effect of K-Ras mutations in patients having received exclusive 5-FU therapy.

    This study was conducted on 93 stage IV colorectal cancer patients with unresectable measurable liver metastasis receiving 5-FU-leucovorin (56 men and 37 women; 77 cancer deaths). Liver metastases (n = 93) along with primary tumors (n = 48) were analyzed for K-Ras mutations (codons 12 and 13), p53 mutations (exons 4-9), p53 polymorphism (codon 72), thymidylate synthase (TS) polymorphism (28-bp repeats including G>C mutation), methylenetetrahydrofolate reductase polymorphism (677C>T, 1298A>C), thymidylate synthase (TS) activity, dihydropyrimidine dehydrogenase activity, folylpolyglutamate synthase activity, and p53 protein expression.

    Results: Thirty-six of 93 (38.7%) metastases were K-Ras mutated (30 at codon 12 and 6 at codon 13). Mutated primary tumors (16 of 48) matched perfectly with mutated metastases. The additional analyzed tumor markers were not different between K-Ras mutated and wild-type tumors. The objective response rate was 37%: 44.4% in K-Ras mutated versus 32.1% in wild-type K-Ras metastasis (P = 0.27). Low TS activity in metastasis was the only significant predictor of tumor response (P = 0.047). K-Ras status did not influence specific survival.

    Conclusions: The present data indicate a perfect concordance of K-Ras mutations between primary and liver metastasis and suggest that any predictive and/or prognostic value of K-Ras mutations in treatments combining anti-EGFR monoclonal antibodies with 5-FU should be exclusively linked to the anti-EGFR agent.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2008;14;15;4830-5

  • Loss of integrin alpha1beta1 ameliorates Kras-induced lung cancer.

    Macias-Perez I, Borza C, Chen X, Yan X, Ibanez R, Mernaugh G, Matrisian LM, Zent R and Pozzi A

    Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Veterans Affairs Hospital, Nashville, Tennessee 37232, USA.

    The collagen IV binding receptor integrin alpha1beta1 has been shown to regulate lung cancer due to its proangiogenic properties; however, it is unclear whether this receptor also plays a direct role in promoting primary lung tumors. To investigate this possibility, integrin alpha1-null mice were crossed with KrasLA2 mice that carry an oncogenic mutation of the Kras gene (G12D) and develop spontaneous primary tumors with features of non-small cell lung cancer. We provide evidence that KrasLA2/alpha1-null mice have a decreased incidence of primary lung tumors and longer survival compared with KrasLA2/alpha1 wild-type controls. Tumors from KrasLA2/alpha1-null mice were also smaller, less vascularized, and exhibited reduced cell proliferation and increased apoptosis, as determined by proliferating cell nuclear antigen and terminal deoxynucleotidyl-transferase-mediated dUTP nick-end staining, respectively. Moreover, tumors from the KrasLA2/alpha1-null mice showed diminished extracellular signal-regulated kinase (ERK) but enhanced p38 mitogen-activated protein kinase activation. Primary lung tumor epithelial cells isolated from KrasLA2/alpha1-null mice showed a significant decrease in anchorage-independent colony formation, collagen-mediated cell proliferation, ERK activation, and, most importantly, tumorigenicity when injected into nude mice compared with KrasLA2/alpha1 wild-type tumor cells. These results indicate that loss of the integrin alpha1 subunit decreases the incidence and growth of lung epithelial tumors initiated by oncogenic Kras, suggesting that both Kras and integrin alpha1beta1 cooperate to drive the growth of non-small cell lung cancer in vivo.

    Funded by: NCI NIH HHS: P50 CA090949, P50 CA090949-05, P50CA090949, R01 CA094849, R01 CA094849-01A1, R01 CA94849-01; NIDDK NIH HHS: R01 DK069921-05, R01 DK075594-02, R01-DK 69921, R01-DK075594

    Cancer research 2008;68;15;6127-35

  • Clinicopathological and molecular analysis of endometrial carcinoma associated with tamoxifen.

    Turbiner J, Moreno-Bueno G, Dahiya S, Sánchez-Estevez C, Hardisson D, Prat J, Oliva E and Palacios J

    Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA. jturbiner@partners.org

    Use of tamoxifen for treatment and prevention of breast cancer is becoming increasingly common. Tamoxifen has been associated with increased risk of endometrial carcinoma, although the exact mechanism of action is unknown. The aim of our study was to seek a possible correlation between endometrial carcinoma, tamoxifen exposure and MSI, PTEN, beta-catenin and K-ras abnormalities. A group of 18 patients with endometrial carcinoma following treatment with tamoxifen were selected. A control group included 15 patients with endometrial carcinoma and associated ovarian hyperthecosis and one patient with endometrial carcinoma and adult granulosa cell tumor of the ovary, chosen because both conditions are associated with increased production of estrogen and increased risk of endometrial carcinoma development. The second control group included 27 randomly selected consecutive patients with endometrial carcinoma without identifiable associated conditions. Immunostaining for beta-catenin was performed on all cases; DNA was extracted and amplified by PCR with primers for beta-catenin, K-ras and PTEN genes. BAT-25 and BAT-26 were analyzed to assess for MSI. There were 16 endometrioid endometrial carcinomas, one mixed carcinoma and one clear cell carcinoma among patients in the tamoxifen group. All patients with ovarian hyperthecosis and adult granulosa cell tumor had endometrioid endometrial carcinoma. In the random control group, there were 26 endometrioid endometrial carcinomas and one carcinosarcoma. Immunohistochemical and mutational analysis for beta-catenin showed abnormalities in 4/11 (36%) and 3/10 (30%) informative cases in the tamoxifen group; 7/16 (44%) and 4/15 (27%) informative cases, respectively in the ovarian hyperthecosis group and 1/27 random control cases (4%) (P<0.05). Patients with tamoxifen exposure had more K-ras mutations and fewer PTEN mutations and MSI as opposed to controls, but the results were not statistically significant. In conclusion, there was a direct relationship between tamoxifen exposure and overexpression of beta-catenin oncoprotein, which is known to play a major role in the pathogenesis of estrogen-driven, type I endometrial adenocarcinoma.

    Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc 2008;21;8;925-36

  • Endothelial nitric oxide synthase regulates N-Ras activation on the Golgi complex of antigen-stimulated T cells.

    Ibiza S, Pérez-Rodríguez A, Ortega A, Martínez-Ruiz A, Barreiro O, García-Domínguez CA, Víctor VM, Esplugues JV, Rojas JM, Sánchez-Madrid F and Serrador JM

    Departamento de Biología Vascular e Inflamación, Centro Nacional de Investigaciones Cardiovasculares, E-28029 Madrid, Spain.

    Ras/ERK signaling plays an important role in T cell activation and development. We recently reported that endothelial nitric oxide synthase (eNOS)-derived NO regulates T cell receptor (TCR)-dependent ERK activation by a cGMP-independent mechanism. Here, we explore the mechanisms through which eNOS exerts this regulation. We have found that eNOS-derived NO positively regulates Ras/ERK activation in T cells stimulated with antigen on antigen-presenting cells (APCs). Intracellular activation of N-, H-, and K-Ras was monitored with fluorescent probes in T cells stably transfected with eNOS-GFP or its G2A point mutant, which is defective in activity and cellular localization. Using this system, we demonstrate that eNOS selectively activates N-Ras but not K-Ras on the Golgi complex of T cells engaged with APC, even though Ras isoforms are activated in response to NO from donors. We further show that activation of N-Ras involves eNOS-dependent S-nitrosylation on Cys(118), suggesting that upon TCR engagement, eNOS-derived NO directly activates N-Ras on the Golgi. Moreover, wild-type but not C118S N-Ras increased TCR-dependent apoptosis, suggesting that S-nitrosylation of Cys(118) contributes to activation-induced T cell death. Our data define a signaling mechanism for the regulation of the Ras/ERK pathway based on the eNOS-dependent differential activation of N-Ras and K-Ras at specific cell compartments.

    Proceedings of the National Academy of Sciences of the United States of America 2008;105;30;10507-12

  • Mutations in the LKB1 tumour suppressor are frequently detected in tumours from Caucasian but not Asian lung cancer patients.

    Koivunen JP, Kim J, Lee J, Rogers AM, Park JO, Zhao X, Naoki K, Okamoto I, Nakagawa K, Yeap BY, Meyerson M, Wong KK, Richards WG, Sugarbaker DJ, Johnson BE and Jänne PA

    Lowe Center for Thoracic Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.

    Somatic mutations of LKB1 tumour suppressor gene have been detected in human cancers including non-small cell lung cancer (NSCLC). The relationship between LKB1 mutations and clinicopathological characteristics and other common oncogene mutations in NSCLC is inadequately described. In this study we evaluated tumour specimens from 310 patients with NSCLC including those with adenocarcinoma, adenosquamous carcinoma, and squamous cell carcinoma histologies. Tumours were obtained from patients of US (n=143) and Korean (n=167) origin and screened for LKB1, KRAS, BRAF, and EGFR mutations using RT-PCR-based SURVEYOR-WAVE method followed by Sanger sequencing. We detected mutations in the LKB1 gene in 34 tumours (11%). LKB1 mutation frequency was higher in NSCLC tumours of US origin (17%) compared with 5% in NSCLCs of Korean origin (P=0.001). They tended to occur more commonly in adenocarcinomas (13%) than in squamous cell carcinomas (5%) (P=0.066). LKB1 mutations associated with smoking history (P=0.007) and KRAS mutations (P=0.042) were almost mutually exclusive with EGFR mutations (P=0.002). The outcome of stages I and II NSCLC patients treated with surgery alone did not significantly differ based on LKB1 mutation status. Our study provides clinical and molecular characteristics of NSCLC, which harbour LKB1 mutations.

    Funded by: NCI NIH HHS: 1R01CA114465-01, P20CA90578-02, R01 CA114465-03

    British journal of cancer 2008;99;2;245-52

  • Primary resistance to cetuximab therapy in EGFR FISH-positive colorectal cancer patients.

    Cappuzzo F, Varella-Garcia M, Finocchiaro G, Skokan M, Gajapathy S, Carnaghi C, Rimassa L, Rossi E, Ligorio C, Di Tommaso L, Holmes AJ, Toschi L, Tallini G, Destro A, Roncalli M, Santoro A and Jänne PA

    Department of Medical Oncology, Istituto Clinico Humanitas IRCCS, Milan University, Rozzano, Italy. federico.cappuzzo@humanitas.it

    The impact of KRAS mutations on cetuximab sensitivity in epidermal growth factor receptor fluorescence in situ hybridisation-positive (EGFR FISH+) metastatic colorectal cancer patients (mCRC) has not been previously investigated. In the present study, we analysed KRAS, BRAF, PI3KCA, MET, and IGF1R in 85 mCRC treated with cetuximab-based therapy in whom EGFR status was known. KRAS mutations (52.5%) negatively affected response only in EGFR FISH+ patients. EGFR FISH+/KRAS mutated had a significantly lower response rate (P=0.04) than EGFR FISH+/KRAS wild type patients. Four EGFR FISH+ patients with KRAS mutations responded to cetuximab therapy. BRAF was mutated in 5.0% of patients and none responded to the therapy. PI3KCA mutations (17.7%) were not associated to cetuximab sensitivity. Patients overexpressing IGF1R (74.3%) had significantly longer survival than patients with low IGF1R expression (P=0.006), with no difference in response rate. IGF1R gene amplification was not detected, and only two (2.6%) patients, both responders, had MET gene amplification. In conclusion, KRAS mutations are associated with cetuximab failure in EGFR FISH+ mCRC, even if it does not preclude response. The rarity of MET and IGF1R gene amplification suggests a marginal role in primary resistance. The potential prognostic implication of IGF1R expression merits further evaluation.

    British journal of cancer 2008;99;1;83-9

  • Human germline and somatic cells have similar TP53 and Kirsten-RAS gene single base mutation frequencies.

    Cole DN, Carlson JA and Wilson VL

    Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA.

    Understanding the risk of offspring inheriting rare mutations, and the frequencies at which these mutations are present in germ cells can be explored with direct analysis of human semen samples. The present work utilized the ultrasensitive PCR/RE/LCR mutation assay to detect, identify and determine the prevalence single base substitution mutations in the TP53 and KRAS genes in human sperm. Four disease-associated base sites in the TP53 and KRAS genes, three of which are known to be heritable to live, term offspring, were studied in sperm from eleven human semen specimens. Eight of the specimens (73%) displayed single base substitution mutations, and 30% of all base sites tested were found to harbor mutations ranging in prevalence from 1 x 10(-6) to 1 x 10(-5) wild type sperm. These germ cell single base substitution mutation frequencies are very similar to somatic tissue TP53 and KRAS mutation frequencies. Equivalent single base mutation frequencies in both germ and somatic cells suggest that there is no unusual selection or mutation protective process operating premeiotically in the germline, and that a selection bias at the level of sperm viability, conception, early cleavage, implantation, and/or embryogenesis operates to exclude the majority of these TP53 mutations and all of the activating KRAS mutations.

    Environmental and molecular mutagenesis 2008;49;6;417-25

  • RAS signaling in colorectal carcinomas through alteration of RAS, RAF, NF1, and/or RASSF1A.

    Ahlquist T, Bottillo I, Danielsen SA, Meling GI, Rognum TO, Lind GE, Dallapiccola B and Lothe RA

    Department of Cancer Prevention, Institute for Cancer Research, Norwegian Radium Hospital, Rikshospitalet University Hospital, Oslo, Norway.

    More than half of all colorectal carcinomas are known to exhibit an activated mitogen-activated protein kinase pathway. The NF1 gene, a negative regulator of KRAS, has not previously been examined in a series of colorectal cancer. In the present study, primary colorectal carcinomas stratified according to microsatellite instability status were analyzed. The whole coding region of NF1 was analyzed for mutations using denaturing high-performance liquid chromatography and sequencing, and the copy number alterations of NF1 were examined using multiple ligation-dependent probe amplification and real-time polymerase chain reaction. The mutational hot spots in KRAS and BRAF were sequenced, and promoter hypermethylation status of RASSF1A was assessed with a methylation-specific polymerase chain reaction. One sample had two missense mutations in NF1, whereas nine additional tumors had intronic mutations likely to affect exon splicing. Interestingly, 8 of these 10 tumors were microsatellite-unstable. Four other tumors showed a duplication of NF1. Mutations in KRAS and BRAF were mutually exclusive and were present at 40% and 22%, respectively. RASSF1A was hypermethylated in 31% of the samples. We show that the RAS signaling network is extensively dysregulated in colorectal carcinomas, because more than 70% of the tumors had an alteration in one or more of the four examined components.

    Neoplasia (New York, N.Y.) 2008;10;7;680-6, 2 p following 686

  • Suppression of colorectal oncogenesis by selenium-enriched milk proteins: apoptosis and K-ras mutations.

    Hu Y, McIntosh GH, Le Leu RK, Woodman R and Young GP

    Department of Medicine, Flinders Cancer Control Alliance, Flinders University of South Australia, Adelaide, Australia. ying.hu@flinders.edu.au

    The chemical form and bioavailability of dietary selenium may influence its protectiveness against colorectal cancer. Selenium is readily incorporated into milk proteins by feeding cows with selenized-yeast. This study examined whether a dairy source of organic selenium (as milk proteins) is more effective than a yeast source at inhibiting oncogenesis in carcinogen-treated mice and whether it regulates the homeostatic response to carcinogen-induced DNA damage. Dietary interventions are as follows: selenium-enriched milk protein isolate (Tatura-Bio Se; 0.5 or 1 ppm selenium) or milk protein control and selenized-yeast (Sel-Plex; 1 or 4 ppm selenium) with casein or casein alone as control. After 4 weeks on diet, mice received a single azoxymethane (10 mg/kg) injection to induce mutations and were killed 6 hours later. Measures were as follows: plasma selenium, cell proliferation, and acute apoptotic response to azoxymethane (AARGC). Separate groups of mice on the same diets were given 4 weekly azoxymethane (15 mg/kg) injections to induce oncogenesis. Mice were killed 6 or 30 weeks after the last azoxymethane injection. Measures were as follows: aberrant crypt foci (ACF), cancers, and K-ras mutations. Dairy-selenium at 1 ppm significantly suppressed ACF and cancers, whereas yeast-selenium at an equivalent selenium intake had no effect. Dairy-selenium significantly increased plasma selenium levels and AARGC, and reduced cell proliferation and frequency of K-ras mutations in ACF relative to an equivalent dose of selenium from yeast. Selenium-enriched milk protein isolate is superior to selenized-yeast in terms of its bioavailability and capacity to suppress oncogenesis. Suppression may be a consequence of enhanced apoptotic deletion of azoxymethane-induced DNA lesions and the subsequent reduction in frequency of K-ras mutations.

    Cancer research 2008;68;12;4936-44

  • A polymorphism of EGFR extracellular domain is associated with progression free-survival in metastatic colorectal cancer patients receiving cetuximab-based treatment.

    Gonçalves A, Esteyries S, Taylor-Smedra B, Lagarde A, Ayadi M, Monges G, Bertucci F, Esterni B, Delpero JR, Turrini O, Lelong B, Viens P, Borg JP, Birnbaum D, Olschwang S and Viret F

    Department of Medical Oncology, Institut Paoli-Calmettes, Marseille, France. goncalves.anthony2@orange.fr

    Background: Cetuximab, a monoclonal antibody targeting Epidermal Growth Factor Receptor (EGFR), is currently used in metastatic colorectal cancer (mCRC), but predictive factors for therapeutic response are lacking. Mutational status of KRAS and EGFR, and EGFR copy number are potential determinants of cetuximab activity.

    Methods: We analyzed tumor tissues from 32 EGFR-positive mCRC patients receiving cetuximab/irinotecan combination and evaluable for treatment response. EGFR copy number was quantified by fluorescence in situ hybridization (FISH). KRAS exon 1 and EGFR exons coding for extracellular regions were sequenced.

    Results: Nine patients experienced an objective response (partial response) and 23 were considered as nonresponders (12 with stable disease and 11 with progressive disease). There was no EGFR amplification found, but high polysomy was noted in 2 patients, both of which were cetuximab responders. No EGFR mutations were found but a variant of exon 13 (R521K) was observed in 12 patients, 11 of which achieved objective response or stable disease. Progression-free and overall survivals were significantly better in patients with this EGFR exon 13 variant. KRAS mutations were found in 14 cases. While there was a trend for an increased KRAS mutation frequency in nonresponder patients (12 mutations out of 23, 52%) as compared to responder patients (2 out of 9, 22%), authentic tumor response or long-term disease stabilization was found in KRAS mutated patients.

    Conclusion: This preliminary study suggests that: an increase in EGFR copy number may be associated with cetuximab response but is a rare event in CRC, KRAS mutations are associated with low response rate but do not preclude any cetuximab-based combination efficacy and EGFR exon 13 variant (R521K) may predict for cetuximab benefit.

    BMC cancer 2008;8;169

  • [Molecular pathologic KRAS mutation analysis. A prerequisite of effective antibody treatment for metastasized colorectal cancer].

    Dietel M, Tannapfel A, Baretton G, Kreipe H, Kloor M, Gabbert H and Kirchner T

    Institut für Pathologie, Charité - Universitätsmedizin Berlin,Campus Mitte, Charitéplatz 1, 10117, Berlin, Deutschland. manfred.dietel@charite.de

    Der Chirurg; Zeitschrift für alle Gebiete der operativen Medizen 2008;79;6;576-9

  • Mutations in both KRAS and BRAF may contribute to the methylator phenotype in colon cancer.

    Nagasaka T, Koi M, Kloor M, Gebert J, Vilkin A, Nishida N, Shin SK, Sasamoto H, Tanaka N, Matsubara N, Boland CR and Goel A

    Division of Gastroenterology, Department of Internal Medicine, and Charles A. Sammons Cancer Center and Baylor Research Institute, Baylor University Medical Center, Dallas, Texas 75246, USA.

    Colorectal cancers (CRCs) with the CpG island methylator phenotype (CIMP) often associate with epigenetic silencing of hMLH1 and an activating mutation in the BRAF gene. However, the current CIMP criteria are ambiguous and often result in an underestimation of CIMP frequencies in CRCs. Because BRAF and KRAS belong to same signaling pathway, we hypothesized that not only mutations in BRAF but mutant KRAS may also associate with CIMP in CRC.

    Methods: We determined the methylation status in a panel of 14 markers (7 canonical CIMP-related loci and 7 new loci), microsatellite instability status, and BRAF/KRAS mutations in a collection of 487 colorectal tissues that included both sporadic and Lynch syndrome patients.

    Results: Methylation analysis of 7 CIMP-related markers revealed that the mean number of methylated loci was highest in BRAF-mutated CRCs (3.6) vs KRAS-mutated (1.2, P < .0001) or BRAF/KRAS wild-type tumors (0.7, P < .0001). However, analyses with 7 additional markers showed that the mean number of methylated loci in BRAF mutant tumors (4.4) was the same as in KRAS mutant CRCs (4.3, P = .8610). Although sporadic microsatellite instability high tumors had the highest average number of methylated markers (8.4), surprisingly, Lynch syndrome CRCs also demonstrated frequent methylation (5.1).

    Conclusions: CIMP in CRC may result from activating mutations in either BRAF or KRAS, and the inclusion of additional methylation markers that correlate with mutant KRAS may help clarify CIMP in future studies. Additionally, aberrant DNA methylation is a common event not only in sporadic CRC but also in Lynch syndrome CRCs.

    Funded by: NCI NIH HHS: R01 CA072851, R01 CA072851-10, R01 CA072851-13, R01 CA098572, R01 CA098572-05, R01 CA72851, R01 CA98572

    Gastroenterology 2008;134;7;1950-60, 1960.e1

  • Oncogenic KRAS induces progenitor cell expansion and malignant transformation in zebrafish exocrine pancreas.

    Park SW, Davison JM, Rhee J, Hruban RH, Maitra A and Leach SD

    Department of Surgery, The Sol Goldman Center for Pancreatic Cancer Research, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.

    Although the cell of origin for pancreatic cancer remains unknown, prior studies have suggested that pancreatic neoplasia may be initiated in progenitor-like cells. To examine the effects of oncogene activation within the pancreatic progenitor pool, we devised a system for real-time visualization of both normal and oncogenic KRAS-expressing pancreatic progenitor cells in living zebrafish embryos.

    Methods: By using BAC transgenes under the regulation of ptf1a regulatory elements, we expressed either extended green fluorescent protein (eGFP) alone or eGFP fused to oncogenic KRAS in developing zebrafish pancreas.

    Results: After their initial specification, normal eGFP-labeled pancreatic progenitor cells were observed to actively migrate away from the forming endodermal gut tube, and subsequently underwent characteristic exocrine differentiation. In contrast, pancreatic progenitor cells expressing oncogenic KRAS underwent normal specification and migration, but failed to differentiate. This block in differentiation resulted in the abnormal persistence of an undifferentiated progenitor pool, and was associated with the subsequent formation of invasive pancreatic cancer. These tumors showed several features in common with the human disease, including evidence of abnormal Hedgehog pathway activation.

    Conclusions: These results provide a unique view of the tumor-initiating effects of oncogenic KRAS in a living vertebrate organism, and suggest that zebrafish models of pancreatic cancer may prove useful in advancing our understanding of the human disease.

    Funded by: NIDDK NIH HHS: DK56211, DK61215, R01 DK056211, R01 DK056211-11, R01 DK061215, R01 DK061215-05

    Gastroenterology 2008;134;7;2080-90

  • Structural polymorphism within a regulatory element of the human KRAS promoter: formation of G4-DNA recognized by nuclear proteins.

    Cogoi S, Paramasivam M, Spolaore B and Xodo LE

    Department of Biomedical Science and Technology, School of Medicine, Ple. Kolbe 4, 33100 Udine and CRIBI Biotechnology Centre, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy.

    The human KRAS proto-oncogene contains a critical nuclease hypersensitive element (NHE) upstream of the major transcription initiation site. In this article, we demonstrate by primer-extension experiments, PAGE, chemical footprinting, CD, UV and FRET experiments that the G-rich strand of NHE (32R) folds into intra-molecular G-quadruplex structures. Fluorescence data show that 32R in 100 mM KCl melts with a biphasic profile, showing the formation of two distinct G-quadruplexes with T(m) of approximately 55 degrees C (Q(1)) and approximately 72 degrees C (Q(2)). DMS-footprinting and CD suggest that Q(1) can be a parallel and Q(2) a mixed parallel/antiparallel G-quadruplex. When dsNHE (32R hybridized to its complementary) is incubated with a nuclear extract from Panc-1 cells, three DNA-protein complexes are observed by EMSA. The complex of slower mobility is competed by quadruplex 32R, but not by mutant oligonucleotides, which cannot form a quadruplex structure. Using paramagnetic beads coupled with 32R, we pulled down from the Panc-1 extract proteins with affinity for quadruplex 32R. One of these is the heterogeneous nuclear ribonucleoprotein A1, which was previously reported to unfold quadruplex DNA. Our study suggests a role of quadruplex DNA in KRAS transcription and provides the basis for the rationale design of molecular strategies to inhibit the expression of KRAS.

    Nucleic acids research 2008;36;11;3765-80

  • Explaining the preponderance of Kras mutations in human cancer: An isoform-specific function in stem cell expansion.

    Quinlan MP and Settleman J

    Center for Molecular Therapeutics, Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachussets, USA.

    Mutationally activated forms of the three closely related Ras isoforms, Kras, Hras and Nras can each exert oncogenic activity, and activated alleles arise in a variety of human cancers. However, mutant Kras is, by far, the most frequently observed Ras isoform in cancer, and is most frequently detected in tumors derived from endodermal tissues, including pancreas, lung and colon. We have recently reported findings that may explain this. We observed that activated Kras, but not Hras or Nras, promotes the expansion of an endodermal stem/progenitor cell and blocks its differentiation. Thus, Kras may uniquely contribute to the initiation of tumors in endodermally-derived tissues by expanding a stem/progenitor cell population.

    Cell cycle (Georgetown, Tex.) 2008;7;10;1332-5

  • Mutations in the RAS-MAPK, PI(3)K (phosphatidylinositol-3-OH kinase) signaling network correlate with poor survival in a population-based series of colon cancers.

    Barault L, Veyrie N, Jooste V, Lecorre D, Chapusot C, Ferraz JM, Lièvre A, Cortet M, Bouvier AM, Rat P, Roignot P, Faivre J, Laurent-Puig P and Piard F

    INSERM, U866, Dijon, F-21079, France.

    The RAS-MAPK, PI (3)K signaling pathways form a network that play a central role in tumorigenesis. The BRAF, KRAS and PI3KCA genes code 3 partners of this network and have been found to be activated by mutation in colorectal cancer; these mutations lead to unrestricted cell growth. We evaluated the clinicopathological features and the prognosis of patients with activated-network colon cancers in a population-based study. A total of 586 colon adenocarcinomas were evaluated using sequencing for mutations of KRAS and PI3KCA, and allelic discrimination for mutation of BRAF. Clinicopathological characteristics were correlated to the risk of bearing a mutation of the network using logistic regression. Three-year survival rates were compared with the Log rank test. A multivariate survival analysis using the Cox model was performed. After adjustment for age and microsatellite instability, activation of the network by mutation of at least 1 of the 3 genes was significantly associated with female sex (p = 0.02) and proximal location (p < 0.001). Lower levels of 3-year survival were associated with activation of the network by mutation of at least 1 of the 3 genes (59.4 and 69.4%, respectively; p = 0.009). These results remained significant in a multivariate analysis adjusted for sex, age, location, stage and microsatellite instability (HR = 1.48; CI CI(95%) = [1.07-2.04]). Our study is the first report to underline the potential role of RAS-MAPK, PI (3)K network mutations on survival in colon cancers. Because of the role of this signaling network on anticancer agents, the evaluation of its mutations could have clinical implications.

    International journal of cancer 2008;122;10;2255-9

  • Association of K-ras mutational status and clinical outcomes in patients with metastatic colorectal cancer receiving panitumumab alone.

    Freeman DJ, Juan T, Reiner M, Hecht JR, Meropol NJ, Berlin J, Mitchell E, Sarosi I, Radinsky R and Amado RG

    Department of Oncology Research, Amgen Inc, Thousand Oaks, CA 91320, USA. dfreeman@amgen.com

    Background: Identifying predictive biomarkers is important to optimally treat patients. This analysis evaluated the association of K-ras, BRAF, and PIK3CA gene mutations with tumor resistance to panitumumab alone.

    From 3 phase II panitumumab metastatic colorectal cancer (mCRC) studies, 62 of 533 patient samples were available. Mutations were identified from genomic DNA by sequencing.

    Results: Of the 62 samples, 24 (38.7%) harbored a K-ras mutation, and 38 (61.3%) were wild type. In the wild-type K-ras group, 11% of patients had a partial response (PR), 53% had stable disease (SD), and 37% had progressive disease (PD). In the mutant K-ras group, 21% of patients had SD, and 79% of patients had PD; there were no responses. The absence of a K-ras mutation was associated with response to panitumumab (PR vs. SD vs. PD; P = .0028). The hazard ratio for wild-type versus mutant K-ras was 0.4 (95% CI, 0.2-0.7) for progression-free survival and 0.5 (95% CI, 0.3-0.9) for overall survival. Four patients had a V600E BRAF mutation, and 2 patients had a PIK3CA mutation.

    Conclusion: These data suggest that patients with mCRC with activating K-ras mutations are less likely to respond to panitumumab alone. The small sample size limits us from defining a predictive role of PIK3CA and BRAF mutations for panitumumab treatment.

    Clinical colorectal cancer 2008;7;3;184-90

  • Association of KRAS polymorphisms with risk for lung adenocarcinoma accompanied by atypical adenomatous hyperplasias.

    Kohno T, Kunitoh H, Suzuki K, Yamamoto S, Kuchiba A, Matsuno Y, Yanagitani N and Yokota J

    Biology Division, National Cancer Center Research Institute, Tokyo 1040045, Japan.

    The pulmonary adenoma susceptibility 1 (Pas1) gene affects susceptibility to the development of lung adenomas in mice with a subset of the adenomas progressing to adenocarcinoma (ADC). In this study, genotype distributions for 10 polymorphisms in the human counterparts for three mouse candidate Pas1 genes, KRAS, CASC1/LAS1 and LRMP, were examined in a hospital-based case-control study consisting of 364 lung ADC cases and 253 controls. All the ADC cases were subjected to lobectomy and subsequent pathological investigation of atypical adenomatous hyperplasia (AAH), a putative precursor for peripheral lung ADC, including bronchioloalveolar carcinoma, in the resected lobes. Eighty-one (22%) of the ADC cases carried at least one AAH lesion in addition to the primary ADC and 34 (9%) of them carried multiple AAH lesions. None of the 10 polymorphisms examined showed significant associations with overall lung ADC risk (P > 0.05). However, minor allele carriers for two polymorphisms in the KRAS gene, KRAS-1 and -6, showed significantly increased odds ratios (ORs) for ADC accompanied by multiple AAHs [OR = 3.0; 95% confidence interval (CI) = 1.4-6.2, P = 0.004 and OR = 2.4; 95% CI = 1.1-4.7, P = 0.02, respectively]. Minor haplotypes including the minor allele for the KRAS-6 polymorphism showed increased ORs for ADC accompanied by multiple AAHs, and KRAS transcripts from the minor allele for this polymorphism were more abundantly detected in lung tissues than those from the major allele. Thus, KRAS polymorphisms were indicated to be involved in risk for the development of AAHs that progress to ADC by causing differential KRAS oncogene expression in the lungs.

    Carcinogenesis 2008;29;5;957-63

  • PIK3CA, HRAS and KRAS gene mutations in human penile cancer.

    Andersson P, Kolaric A, Windahl T, Kirrander P, Söderkvist P and Karlsson MG

    Division of Cell Biology, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden. patan@ibk.liu.se <e-mail:patan@ibk.liu.se&gt;

    Purpose: The knowledge of somatic mutations that arise in penile cancer is limited. We examined the dysregulation of components in the phosphatidylinositol 3-kinase and Ras pathways.

    Using single stranded conformational analysis and direct sequencing we performed mutational analysis of the PIK3CA, PTEN, HRAS, KRAS, NRAS and BRAF genes in 28 penile tumors.

    Results: We identified somatic missense mutations in 11 of the 28 penile cancer samples (39%). In the PIK3CA gene 8 mutations (29%) were identified that were E542K or E545K. In the HRAS gene a G12S and a Q61L mutation were found (7%). The KRAS gene contained 1 mutation (3%), that is a G12S change. PIK3CA mutations were found in all grades and stages, whereas HRAS and KRAS mutations were found in larger and more advanced tumors. The mutations were mutually exclusive, suggesting that dysregulation of either pathway is sufficient for the development and progression of penile carcinoma.

    Conclusions: The high frequency of mutations in the PIK3CA, HRAS and KRAS genes leads us to believe that dysregulation of the phosphatidylinositol 3-kinase or Ras pathway is significant for the development and progression of penile carcinoma.

    The Journal of urology 2008;179;5;2030-4

  • PIK3CA, KRAS, and BRAF mutations in intraductal papillary mucinous neoplasm/carcinoma (IPMN/C) of the pancreas.

    Schönleben F, Qiu W, Remotti HE, Hohenberger W and Su GH

    Department of General Surgery, Friedrich-Alexander-University of Erlangen-Nuremberg, Erlangen, Germany. frank.schoenleben@gmx.de

    Recent studies have reported high frequencies of somatic mutations in the phosphoinositide-3-kinase catalytic-alpha (PIK3CA) gene in various human tumors. Three hot-spot mutations in the exons 9 and 20 have been proven to activate the Akt signalling pathway. The Raf/MEK/ERK (mitogen-activated protein kinase) signal transduction is an important mediator of a number of cellular fates including growth, proliferation, and survival. The BRAF gene is activated by oncogenic RAS, leading to cooperative effects in cells responding to growth factor signals. Here we evaluate the mutational status of PIK3CA, KRAS, and BRAF in intraductal papillary mucinous neoplasm/carcinoma (IPMN/IPMNC) of the pancreas.

    Exons 1, 4, 5, 6, 7, 9, 12, 18, and 20 of PIK3CA, exons 1 of KRAS, and exons 5, 11, and 15 of BRAF were analyzed in 36 IPMN/IPMC and two mucinous cystadenoma specimens by direct genomic DNA sequencing.

    Results: We identified four somatic missense mutations of PIK3CA within the 36 IPMN/IPMC specimens (11%). One of the four mutations, H1047R, has been previously reported to be a hot-spot mutation. Furthermore, we found 17 (47%) KRAS mutations in exon 1 and one missense mutation (2.7%) in exon 15 of BRAF.

    Conclusion: This data is the first report of PIK3CA mutation in pancreatic cancer and it appears to be the first oncogene to be mutated in IPMN/IPMC but not in conventional ductal adenocarcinoma of the pancreas. Our data provide evidence that PIK3CA and BRAF contribute to the tumorigenesis of IPMN/IPMC, but at a lower frequency than KRAS.

    Funded by: NCI NIH HHS: K01 CA095434, K01 CA095434-05, R01 CA109525, R01 CA109525-03, R01 CA109525-04

    Langenbeck's archives of surgery 2008;393;3;289-96

  • Wild-type KRAS is required for panitumumab efficacy in patients with metastatic colorectal cancer.

    Amado RG, Wolf M, Peeters M, Van Cutsem E, Siena S, Freeman DJ, Juan T, Sikorski R, Suggs S, Radinsky R, Patterson SD and Chang DD

    Amgen, Inc, One Amgen Center Dr, MS 38-2-B, Thousand Oaks, CA 91320-1799, USA. ramado@amgen.com

    Purpose: Panitumumab, a fully human antibody against the epidermal growth factor receptor (EGFR), has activity in a subset of patients with metastatic colorectal cancer (mCRC). Although activating mutations in KRAS, a small G-protein downstream of EGFR, correlate with poor response to anti-EGFR antibodies in mCRC, their role as a selection marker has not been established in randomized trials.

    KRAS mutations were detected using polymerase chain reaction on DNA from tumor sections collected in a phase III mCRC trial comparing panitumumab monotherapy to best supportive care (BSC). We tested whether the effect of panitumumab on progression-free survival (PFS) differed by KRAS status.

    Results: KRAS status was ascertained in 427 (92%) of 463 patients (208 panitumumab, 219 BSC). KRAS mutations were found in 43% of patients. The treatment effect on PFS in the wild-type (WT) KRAS group (hazard ratio [HR], 0.45; 95% CI: 0.34 to 0.59) was significantly greater (P < .0001) than in the mutant group (HR, 0.99; 95% CI, 0.73 to 1.36). Median PFS in the WT KRAS group was 12.3 weeks for panitumumab and 7.3 weeks for BSC. Response rates to panitumumab were 17% and 0%, for the WT and mutant groups, respectively. WT KRAS patients had longer overall survival (HR, 0.67; 95% CI, 0.55 to 0.82; treatment arms combined). Consistent with longer exposure, more grade III treatment-related toxicities occurred in the WT KRAS group. No significant differences in toxicity were observed between the WT KRAS group and the overall population.

    Conclusion: Panitumumab monotherapy efficacy in mCRC is confined to patients with WT KRAS tumors. KRAS status should be considered in selecting patients with mCRC as candidates for panitumumab monotherapy.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2008;26;10;1626-34

  • Activated Kras, but not Hras or Nras, may initiate tumors of endodermal origin via stem cell expansion.

    Quinlan MP, Quatela SE, Philips MR and Settleman J

    Massachusetts General Hospital Cancer Center and Harvard Medical School, 149 13th Street, Charlestown, MA 02129, USA.

    The three closely related human Ras genes, Hras, Nras, and Kras, are all widely expressed, engage a common set of downstream effectors, and can each exhibit oncogenic activity. However, the vast majority of activating Ras mutations in human tumors involve Kras. Moreover, Kras mutations are most frequently seen in tumors of endodermally derived tissues (lung, pancreas, and colon), suggesting that activated Kras may affect an endodermal progenitor to initiate oncogenesis. Using a culture model of retinoic acid (RA)-induced stem cell differentiation to endoderm, we determined that while activated HrasV12 promotes differentiation and growth arrest in these endodermal progenitors, KrasV12 promotes their proliferation. Furthermore, KrasV12-expressing endodermal progenitors fail to differentiate upon RA treatment and continue to proliferate and maintain stem cell characteristics. NrasV12 neither promotes nor prevents differentiation. A structure-function analysis demonstrated that these distinct effects of the Ras isoforms involve their variable C-terminal domains, implicating compartmentalized signaling, and revealed a requirement for several established Ras effectors. These findings indicate that activated Ras isoforms exert profoundly different effects on endodermal progenitors and that mutant Kras may initiate tumorigenesis by expanding a susceptible stem/progenitor cell population. These results potentially explain the high frequency of Kras mutations in tumors of endodermal origin.

    Funded by: NCI NIH HHS: R01 CA109447, R01 CA109447-03

    Molecular and cellular biology 2008;28;8;2659-74

  • EGFR/KRAS mutations and gefitinib therapy in Chinese NSCLC patients.

    Wang Z, Wu YL, Zhang GC, Zhou Q, Xu CR and Guo AL

    Guangdong Provincial People's Hospital, Cancer Center, Guangdong Provincial Lung Cancer Research Institute, Guangzhou, China.

    Background: For gefitinib treatment for non-small cell lung cancer (NSCLC), KRAS mutations reportedly behave as a resistance marker, and the epidermal growth factor receptor (EGFR) as a responsive marker. It is known that Asians and Caucasians have different responses to gefitinib. We investigated the KRAS and EGFR mutation status in a group of Chinese patients with advanced NSCLC who were treated with gefitinib after a failed chemotherapy.

    Genomic DNA extracted from tumor specimens of 24 patients with advanced NSCLC, who failed at least 1 prior platinum-based chemotherapy regimen before gefitinib treatment, was subjected to nested polymerase chain reaction (PCR) to amplify codons 12, 13, 59, and 61 of the KRAS gene and exons 18-21 of the EGFR gene for direct sequencing.

    Results: For the 24 patients, no KRAS gene mutation was found. 15 patients (62.5%, 15/24) harbored EGFR mutations which included deletion mutations in exon 19 and missense mutations in exon 21.

    Conclusion: KRAS mutation may occur at a very low frequency in Chinese NSCLC patients regardless of pathology, smoking status, or gender. Unlike EGFR, the low incidence of KRAS mutations may undermine its role in predicting the clinical response to EGFR tyrosine kinase inhibitors.

    Onkologie 2008;31;4;174-8

  • KRAS wild-type state predicts survival and is associated to early radiological response in metastatic colorectal cancer treated with cetuximab.

    De Roock W, Piessevaux H, De Schutter J, Janssens M, De Hertogh G, Personeni N, Biesmans B, Van Laethem JL, Peeters M, Humblet Y, Van Cutsem E and Tejpar S

    Center for Human Genetics, Katholieke Universiteit Leuven, Leuven, Belgium.

    Background: KRAS mutation status is a candidate marker for predicting survival in patients with metastatic colorectal cancer (mCRC) treated with cetuximab (CTX).

    We studied the KRAS mutation status of 113 patients with irinotecan refractory mCRC treated with CTX in clinical trials. A predictive model for objective response (OR), progression-free survival (PFS) and overall survival (OS) was constructed using logistic and Cox regression.

    Results: OR was seen in 27 of 66 KRAS wild-type (WT) patients versus 0 of 42 in KRAS mutants. Median OS was significantly better in KRAS WT versus mutants (43.0 versus 27.3 weeks; P = 0.020). Decrease in tumor sizes was significantly larger at all time points in WT patients. KRAS WT patients with an initial relative decrease of tumor size >9.66% at week 6 had a significantly better median OS compared with all other patients (74.9 versus 30.6 weeks; P = 0.0000025). Within KRAS WT patients OS was significantly better in patients with an initial decrease compared with those without [median OS: 74.9 versus 30.6 weeks (P = 0.00000012)].

    Conclusions: KRAS WT status is associated to survival benefit in CTX treated mCRC. This benefit is even more pronounced in those patients with early radiological response. These characteristics may be exploited for response prediction.

    Annals of oncology : official journal of the European Society for Medical Oncology / ESMO 2008;19;3;508-15

  • Relationship between overexpression of ras p21 oncoprotein and K-ras codon 12 and 13 mutations in Turkish colorectal cancer patients.

    Akkiprik M, Celikel CA, Düşünceli F, Sönmez O, Güllüoğlu BM, Sav A and Ozer A

    Department of Medical Biology, Marmara University, School of Medicine, Haydarpafla, IstanbulTurkey.

    The activation of ras family genes plays an important role in colorectal tumorigenesis. We investigated the clinicopathological characteristics and point mutations of K-ras oncogene codons 12/13 and ras p21 expression using paraffinembedded materials from cancerous and the surrounding normal tissues of 53 colorectal cancer cases.

    Methods: K-ras codons 12 and 13 point mutations were analyzed by PCR-Single- Strand Conformational Polymorphism (SSCP) and followed by DNA sequencing, while ras p21 expression was evaluated using immunohistochemistry.

    Results: Mutations of K-ras and overexpression of the ras p21 were detected in 11% and 76% of the tumors, respectively. Ras protein level in tumor was increased an average of 4.6-fold over that of normal mucosa. Ras p21 overexpression did not correlate with any of the clinicopathological parameters examined. K-ras gene mutations were found mostly in the presence of a mucinous component within the tumor (p=0.06). Follow-up data were available for 43 patients. There was no statistically significant correlation between these alterations and patient outcomes.

    Conclusions: Our data suggest that, apart from K-ras codons 12/13 point mutations, overexpression of the ras family genes is important in the development of the disease but it appears not to be predictive of survival. Furthermore, mucinous secretion in the colorectum may represent a distinct genetic pattern.

    The Turkish journal of gastroenterology : the official journal of Turkish Society of Gastroenterology 2008;19;1;22-7

  • Sensitive and quantitative detection of KRAS2 gene mutations in pancreatic duct juice differentiates patients with pancreatic cancer from chronic pancreatitis, potential for early detection.

    Shi C, Fukushima N, Abe T, Bian Y, Hua L, Wendelburg BJ, Yeo CJ, Hruban RH, Goggins MG and Eshleman JR

    Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, USA.

    KRAS2 gene mutations are found in 75-90% of infiltrating pancreatic ductal adenocarcinomas but can also be present with other nonneoplastic pancreatic diseases. We recently developed a novel sensitive assay for point mutation detection, called "LigAmp", which can detect one mutant molecule in the presence of 10,000 wild-type molecules and can quantify mutant DNA over a wide dynamic range. We analyzed KRAS2 mutations in surgically-collected pancreatic duct juice samples from patients with pancreatic adenocarcinoma (n = 27) and chronic pancreatitis(n = 9). DNA sequencing demonstrated that 17 of the 27 pancreatic cancers harbored KRAS2 mutations at codon 12, including G12D (GGT-->GAT), G12V (GTT), and G12R (CGT). We determined the relative amounts of each KRAS2 mutant by simultaneously quantifying wild-type and mutant KRAS2 DNA. For all pancreatic adenocarcinoma patients, the dominant KRAS2 mutation detected in the pancreatic juice corresponded to that found in the primary cancer. Mutation levels were substantially higher in patients with pancreatic cancer (0.05 to 82% of total KRAS2 molecules) compared to those with chronic pancreatitis (0 to 0.7%). Among patients with mutant KRAS2 positive cancers, all but one (94%) had mutant KRAS2 DNA concentrations of more than 0.5% in their pancreatic juice samples, whereas only 1 of 9(11%) pancreatic juice samples from patients with chronic pancreatitis had more than 0.5% mutant KRAS2 DNA, corresponding to a sensitivity of 94% and a specificity of 89%. LigAmp quantification of mutant KRAS2 in pancreatic juice differentiates pancreatic adenocarcinoma from chronic pancreatitis, and may be a useful early detection tool for pancreatic cancer.

    Cancer biology & therapy 2008;7;3;353-360

  • Shining the spotlight on shed KRAS in pancreatic cancer.

    Sempere LF and Korc M

    Department of Medicine, Norris Cotton Cancer Center at Dartmouth Hitchcock Medical Center, Dartmouth Medical School, Hanover, NH 03756, USA.

    Cancer biology & therapy 2008;7;3;361-3

  • K-ras mutations in sinonasal cancers in relation to wood dust exposure.

    Bornholdt J, Hansen J, Steiniche T, Dictor M, Antonsen A, Wolff H, Schlünssen V, Holmila R, Luce D, Vogel U, Husgafvel-Pursiainen K and Wallin H

    National Research Centre for the Working Environment, Lersø Parkallé 105, DK-2100 Copenhagen, Denmark. jbo@nrcwe.dk

    Background: Cancer in the sinonasal tract is rare, but persons who have been occupationally exposed to wood dust have a substantially increased risk. It has been estimated that approximately 3.6 million workers are exposed to inhalable wood dust in EU. In previous small studies of this cancer, ras mutations were suggested to be related to wood dust exposure, but these studies were too limited to detect statistically significant associations.

    Methods: We examined 174 cases of sinonasal cancer diagnosed in Denmark in the period from 1991 to 2001. To ensure uniformity, all histological diagnoses were carefully reviewed pathologically before inclusion. Paraffin embedded tumour samples from 58 adenocarcinomas, 109 squamous cell carcinomas and 7 other carcinomas were analysed for K-ras codon 12, 13 and 61 point mutations by restriction fragment length polymorphisms and direct sequencing. Information on occupational exposure to wood dust and to potential confounders was obtained from telephone interviews and from registry data.

    Results: Among the patients in this study, exposure to wood dust was associated with a 21-fold increased risk of having an adenocarcinoma than a squamous cell carcinoma compared to unexposed [OR = 21.0, CI = 8.0-55.0]. K-ras was mutated in 13% of the adenocarcinomas (seven patients) and in 1% of squamous cell carcinomas (one patient). Of these eight mutations, five mutations were located in the codon 12. The exact sequence change of remaining three could not be identified unambiguously. Among the five identified mutations, the G-->A transition was the most common, and it was present in tumour tissue from two wood dust exposed adenocarcinoma patients and one patient with unknown exposure. Previously published studies of sinonasal cancer also identify the GGT --> GAT transition as the most common and often related to wood dust exposure.

    Conclusion: Patients exposed to wood dust seemed more likely to develop adenocarcinoma compared to squamous cell carcinomas. K-ras mutations were detected in 13% of adenocarcinomas. In this study and previously published studies of sinonasal cancer the found K-ras mutations, were almost exclusively G --> A transitions. In conclusion, our study, based on a large representative collection of human SNC tumours, indicates that K-ras mutations are relatively infrequent, and most commonly occur in adenocarcinomas. Wood dust exposure alone was not found to be explanatory for the G-->A mutations, but combination of exposure to tobacco, wood dust, and possibly other occupational agents may be a more likely explanation. Overall, the study suggests a limited role for K-ras mutations in development of sinonasal cancer.

    BMC cancer 2008;8;53

  • Palmitoylation and localisation of RAS isoforms are modulated by the hypervariable linker domain.

    Laude AJ and Prior IA

    Physiological Laboratory, University of Liverpool, Liverpool, UK.

    RAS isoforms have been proposed to exhibit differing biological outputs due to differences in their relative occupancy of cellular organelles and signalling microdomains. The membrane binding and targeting motifs of RAS are encoded by the C-terminal hypervariable region (HVR), and the precise localisation depends upon interactions between the HVR and the host membrane. Classic studies revealed that all RAS proteins rely on farnesylation and either palmitoylation or a polybasic stretch for stable binding to membranes. We now show that, for N-RAS and Ki-RAS4A, mono-palmitoylation and farnesylation are not sufficient for specifying stable cell-surface localisation. A third motif that is present within the linker domain of all palmitoylated RAS HVRs is necessary for stabilising localisation to the plasma membrane. This motif comprises acidic residues that stabilise palmitoylation and basic amino acids that are likely to interact electrostatically with acidic phospholipids enriched at the cell surface. Importantly, altered localisation is achieved without changes in palmitoylation status. Our data provide a mechanism for distinct HVR membrane interactions controlling subcellular distribution. In the context of the full-length RAS proteins, this is likely to be of crucial importance for controlling signalling output and engagement with different pools of effectors.

    Journal of cell science 2008;121;Pt 4;421-7

  • A subset of lung adenocarcinomas and atypical adenomatous hyperplasia-associated foci are genotypically related: an EGFR, HER2, and K-ras mutational analysis.

    Sartori G, Cavazza A, Bertolini F, Longo L, Marchioni A, Costantini M, Barbieri F, Migaldi M and Rossi G

    Section of Pathologic Anatomy, Azienda Policlinico, Modena, Italy.

    Atypical adenomatous hyperplasia (AAH) is considered the preinvasive lesion of pulmonary adenocarcinoma, and mutations of EGFR, HER2, and K-ras are involved in the early stage of lung adenocarcinoma carcinogenesis, also predicting clinical response to anti-EGFR small molecule inhibitors. We analyzed 18 cases of primary lung adenocarcinoma with concomitant AAH foci from 13 patients for mutations of EGFR (exons 18-21), HER2 (exons 19-20), and K-ras (exon 2) by direct sequencing polymerase chain reaction. Among mutated cases, concordant mutations of EGFR or K-ras in adenocarcinoma and related AAH were observed in 5 (63%) of 8 cases. In particular, 3 of 4 adenocarcinomas with EGFR mutations (all L858R point mutations in women, never or former smokers) had a concomitant and identical mutation in AAH, and 2 of 4 adenocarcinomas with K-ras mutations (both at codon 12 in women, a never and a current smoker) showed the same mutation in concomitant AAH. All cases were wild-type for HER2. Mutations of EGFR and K-ras genes represent an early event in lung adenocarcinomagenesis, and AAH convincingly seems to be a precursor lesion in a subset of cases of adenocarcinoma.

    American journal of clinical pathology 2008;129;2;202-10

  • Clinicopathological features of CpG island methylator phenotype-positive colorectal cancer and its adverse prognosis in relation to KRAS/BRAF mutation.

    Lee S, Cho NY, Choi M, Yoo EJ, Kim JH and Kang GH

    Department of Pathology, Kyung Hee University College of Medicine, Seoul, Korea.

    CpG island methylator phenotype (CIMP) is a recently described subset of colorectal cancers (CRC) with widespread methylation of multiple promoter CpG islands. But the prognostic implication of CIMP in CRC has not been clarified. Thus, the aim of the present study was to differentiate the unique characteristics of CIMP from those of microsatellite instability (MSI)-high CRC, especially with regard to prognosis. CIMP, MSI, and mutations of KRAS codons 12 and 13 and of BRAF codon 600 were evaluated in 134 sporadic CRC. Patient survival and other clinicopathological variables were correlated with CIMP or genetic changes. High CIMP, high MSI, and mutations in KRAS or BRAF were detected in 31.3%, 14.2%, 33.6%, and 4.5% of overall CRC, respectively. High CIMP was closely associated with MSI and BRAF mutation but not with KRAS mutation. CIMP-high, microsatellite-stable (MSS) CRC were significantly associated with proximal location and nodal metastasis and had close but non-significant associations with liver metastasis. A worse clinical outcome was found for CIMP-high, MSS CRC with KRAS/BRAF mutation but not for those lacking KRAS/BRAF mutation. The findings support the contention that CIMP-high CRC have distinct clinicopathological and epidemiological features and suggest that the alleged poor clinical outcome of CIMP-high CRC patients is closely associated with the presence of KRAS/BRAF mutation.

    Pathology international 2008;58;2;104-13

  • Cooperating mutations of receptor tyrosine kinases and Ras genes in childhood core-binding factor acute myeloid leukemia and a comparative analysis on paired diagnosis and relapse samples.

    Shih LY, Liang DC, Huang CF, Chang YT, Lai CL, Lin TH, Yang CP, Hung IJ, Liu HC, Jaing TH, Wang LY and Yeh TC

    Division of Hematology-Oncology, Chang Gung Memorial Hospital, Taipei, Taiwan.

    c-KIT mutations have been described in core-binding factor (CBF) acute myeloid leukemia (AML) at diagnosis. The role of c-KIT mutations in the relapse of CBF-AML is not clear. The role of CSF1R mutation in the pathogenesis of AML remains to be determined. We analyzed receptor tyrosine kinases (RTKs) and Ras mutations on 154 children with AML. Also, we examined the paired diagnosis and relapse samples in CBF-AML. CBF-AML accounted for 27% (41/154). c-KIT mutations were detected in 41.5% of CBF-AML at diagnosis (6 in exon 8, 10 in exon 17 and 1 in both exons 8 and 17) , FLT3-TKD 2.7%, N-Ras mutations 7.3% and K-Ras mutations 4.9%. FLT3-LM and CSF1R mutations were not found in CBF-AML. The mutations of RTKs and Ras were mutually exclusive except for one patient who had both c-KIT and N-Ras mutations. Eight of the 41 CBF-AML patients relapsed; four patients retained the identical c-KIT mutation patterns as those at diagnosis, the remaining four without c-KIT mutations at diagnosis did not acquire c-KIT mutations at relapse. Our study showed that 54% of childhood CBF-AML had RTKs and/or Ras mutations; c-KIT but not CSF1R mutations play a role in the leukemogenesis of childhood CBF-AML.

    Leukemia 2008;22;2;303-7

  • Prognostic and therapeutic implications of EGFR and KRAS mutations in resected lung adenocarcinoma.

    Marks JL, Broderick S, Zhou Q, Chitale D, Li AR, Zakowski MF, Kris MG, Rusch VW, Azzoli CG, Seshan VE, Ladanyi M and Pao W

    Human Oncology and Pathogenesis Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.

    Background: Somatic mutations in EGFR (exons 19 and 21) and KRAS (exon 2) are found in lung adenocarcinomas and have potential prognostic value in patients with advanced disease. These mutations also have therapeutic significance, as they predict for sensitivity and resistance, respectively, to EGFR tyrosine kinase inhibitor therapy. Whether EGFR and KRAS mutations also have an impact on survival in patients who undergo lung resection for curative intent in the absence of targeted therapy has not been established.

    Methods: We analyzed the clinical characteristics and outcomes data for 296 patients who underwent resection at our institution for stage I-III lung adenocarcinoma. Tumors were assessed for both EGFR and KRAS mutations by established methods.

    Results: EGFR and KRAS mutations were found in tumors from 40 (14%) and 50 (17%) patients, respectively. Patients with EGFR mutant tumors were more likely to be never smokers (48%), present with stage I disease (88%), and had a 90% (95% confidence interval [CI] 70-97%) 3-year overall survival, whereas patients with KRAS mutant tumors were more likely to be former/current smokers (92%), present with locally advanced disease (40%), and had a 66% (95% CI 48-79%) 3-year overall survival.

    Conclusions: EGFR and KRAS mutations define distinct molecular subsets of resected lung adenocarcinoma. Because EGFR and KRAS mutations also predict whether tumors are sensitive or resistant, respectively, to EGFR tyrosine kinase inhibitors, they can readily be used in clinical trials to help guide the administration of specific types of adjuvant therapy.

    Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer 2008;3;2;111-6

  • KRAS mutations as an independent prognostic factor in patients with advanced colorectal cancer treated with cetuximab.

    Lièvre A, Bachet JB, Boige V, Cayre A, Le Corre D, Buc E, Ychou M, Bouché O, Landi B, Louvet C, André T, Bibeau F, Diebold MD, Rougier P, Ducreux M, Tomasic G, Emile JF, Penault-Llorca F and Laurent-Puig P

    L'Institut National de la Santé et de la Recherche Médicale U775, Université Paris-Descartes, 45 rue des Saints-Pères, 75006 Paris, France.

    Purpose: Cetuximab is efficient in advanced colorectal cancer (CRC). We previously showed that KRAS mutations were associated with resistance to cetuximab in 30 CRC patients. The aim of this study was to validate, in an independent larger series of 89 patients, the prognostic value of KRAS mutations on response to cetuximab and survival.

    Eighty-nine metastatic CRC patients treated with cetuximab after treatment failure with irinotecan-based chemotherapy were analyzed for KRAS mutation by allelic discrimination on tumor DNA. The association between KRAS mutations and tumor response, skin toxicity, progression-free survival (PFS) and overall survival (OS) was analyzed.

    Results: A KRAS mutation was present in 27% of the patients and was associated with resistance to cetuximab (0% v 40% of responders among the 24 mutated and 65 nonmutated patients, respectively; P < .001) and a poorer survival (median PFS: 10.1 v 31.4 weeks in patients without mutation; P = .0001; median OS: 10.1 v 14.3 months in patients without mutation; P = .026). When we pooled these 89 patients with patients from our previous study, the multivariate analysis showed that KRAS status was an independent prognostic factor associated with OS and PFS, whereas skin toxicity was only associated with OS. In a combined analysis, median OS times of patients with two, one, or no favorable prognostic factors (severe skin toxicity and no KRAS mutation) was of 15.6, 10.7, and 5.6 months, respectively.

    Conclusion: These results confirm the high prognostic value of KRAS mutations on response to cetuximab and survival in metastatic CRC patients treated with cetuximab.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2008;26;3;374-9

  • Identification of patients with (atypical) MUTYH-associated polyposis by KRAS2 c.34G > T prescreening followed by MUTYH hotspot analysis in formalin-fixed paraffin-embedded tissue.

    van Puijenbroek M, Nielsen M, Tops CM, Halfwerk H, Vasen HF, Weiss MM, van Wezel T, Hes FJ and Morreau H

    Department of Pathology, Leiden University Medical Center, Leiden, the Netherlands.

    Purpose: To assess the feasibility of identifying patients with (atypical) MUTYH-associated polyposis (MAP) by KRAS2 c.34G > T prescreening followed by MUTYH hotspot mutation analysis in formalin-fixed paraffin-embedded tissue (FFPE).

    Methods: We collected 210 colorectal FFPE tumors from 192 individuals who presented with <10 adenomas or familial mismatch repair proficient colorectal carcinomas with <10 concomitant adenomas. The tissues were tested for somatic KRAS2 mutations and for three Dutch hotspot MUTYH germ line mutations (p.Tyr165Cys, p.Gly382Asp, and p.Pro391Leu) by sequencing analysis.

    Results: The c.34G > T, KRAS2 transversion was detected in 10 of 210 tumors. In one of these 10 cases, a monoallelic p.Gly382Asp MUTYH mutation was found and a full MUTYH analysis in leukocyte DNA revealed an unclassified variant p.Met269Val. This was in a 61-year-old patient with a cecum carcinoma and three adenomas. After further requests, her family case history revealed that her brother had had between 10 and 15 adenomas and turned out to carry both MUTYH germ line mutations. MUTYH hotspot mutation screening in 182 patients without the somatic c.34G > T KRAS2 mutation led to the detection of three monoallelic germ line MUTYH mutation carriers.

    Conclusion: KRAS2 c.34G > T somatic prescreening, followed by MUTYH hotspot mutation analysis when positive, can identify patients with (atypical) MAP. If heterozygous hotspot MUTYH mutations are identified, a complete germ line MUTYH mutation screening should be carried out if possible. Immediate MUTYH hotspot mutation analysis is a practical alternative in patients with >10 adenomas or in cases of multiple colorectal carcinomas in one generation for which only FFPE tissue is available.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2008;14;1;139-42

  • BRAF and K-RAS mutation in a Greek papillary and medullary thyroid carcinoma cohort.

    Goutas N, Vlachodimitropoulos D, Bouka M, Lazaris AC, Nasioulas G and Gazouli M

    Histopathology Department, Evgenidion Hospital, University of Athens, Athens, Greece.

    Background: The genes RAS and BRAF have been shown to be frequently mutated in human thyroid carcinomas. The aim of this study was to genotype a cohort of 55 sporadic papillary thyroid carcinomas (PTC) and 44 sporadic medullary thyroid carcinomas (MTC) for the K-RAS codon 12 and BRAF codon 600 mutations.

    K-RAS and BRAF mutations were characterized by an enhanced polymerase chain reaction followed by restriction fragment length polymorphism analysis (PCR-RFLP).

    Results: The K-RAS codon 12 mutation was found in 54.5% of the PTC and 40.9% of the MTC cases tested. The BRAF V600E mutation was detected in 27.3% of the PTC and 68.2% of the MTC samples. No significant association between K-RAS and BRAF mutations and clinicopathological parameters was found.

    Conclusion: These data indicate that K-RAS and BRAF mutations were a frequent genetic event in our samples of sporadic PTC and MTC.

    Anticancer research 2008;28;1A;305-8

  • Genetic alterations of APC, K-ras, p53, MSI, and MAGE in Korean colorectal cancer patients.

    Jeon CH, Lee HI, Shin IH and Park JW

    Department of Laboratory Medicine, School of Medicine, Catholic University of Daegu, Daegu, South Korea. chjeon@cu.ac.kr

    Colorectal cancer (CRC) is one of the most rapidly increasing cancers in Korea, but no comprehensive analysis has been performed to speculate the genetic basis of CRC development. We investigated the presence of adenomatous polyposis coli gene (APC), Kirsten-ras (K-ras), p53, microsatellite instability (MSI), and melanoma antigen gene (MAGE) alterations in CRC and correlated the results obtained with clinical data.

    We collected 78 cancer tissues from CRC patients. Genetic analyses were performed on APC, K-ras, p53, and MSI (BAT 25 and BAT 26), and in addition, MAGE expression was tested by reverse transcription polymerase chain reaction. Correlations between genetic markers and clinical factors were analyzed after reviewing medical records.

    Result: The positive rates for alterations of APC, K-ras, p53, MSI, and MAGE in 78 tissue samples were 33.3, 29.5, 34.6, 9.0, and 68.4%, respectively. Mutations were frequently detected in codons 1291 and 1450 of APC, in codon 12 of K-ras and in codons 248, 282, and 176 of p53. APC mutations were frequently noted in early-stage cancer, whereas MSI was observed in right-sided and multiple cancers. No associations were found between the presence of alterations in APC, K-ras, p53, MSI, and MAGE.

    Interpretation: In Koreans, positive rates of alterations in APC and p53 were slightly lower than those of APC and p53 in Caucasians, and the genetic alterations including MAGE expression are involved in 92.1% of CRCs. The lack of multiple mutations and of a relation between mutation rates and clinical stage suggest that genetic alterations might have independent influences on CRC development in Koreans.

    International journal of colorectal disease 2008;23;1;29-35

  • [K-ras mutation as a prognostic factor in colorectal carcinoma].

    Sácha M, Havlícek K, Sákra L, Rajman M and Beránek M

    Chirurgická klinika KN, Pardubice.

    Introduction: Colorectal carcinoma presents a serious problem in the Czech Republic: its incidence is on the increase and--according to some statistics takes first place among developed countries worldwide. Therefore, it is advised to incorporate examinational and the rapeutic algorithms with new modalities that will lead to early diagnostics or to a change in existing therapeutic procedures. CHARACTERIZATION OF K-RAS MUTATION: K-ras mutation belongs to the family of protooncogenes where a gene not having undergone mutation expresses proteins that regulate mitosis. Mutation cancels the regulatory function of these proteins, thus leading to the develop ment of tumors, especially carcinoma of the lungs, pancreas, and colorectum. PROJECT OBJECTIVE: The main objective of the project is to prove K-ras mutation in tumors of the colorectum: to detect tumor cells with K-ras mutation in peripheral blood; to detect K-ras mutation in liver metastases: and to verify the hypothesis claiming that tumors with K-ras mutation have a worse prognosis and often lead to disemination, mainly to the liver. METHODOLOGY AND COLLECTION OF DATA: The whole project is tied to an IGA grant and runs according to the strict rules of the protocol applied at the Surgical Clinic of the Pardubice Hospital, with its diagnostic part--PCR analysis being completed at the Biochemical Diagnostic Institute (UKBD) of the Teaching Hospital in Hradec Králové.

    Results: The project has been running since June, 2004 to December 2006. 76 patients meeting defined parameters have been included in the file to date. K-ras mutation has been detected in the tumor tissue of 25 patients (33%). K-ras mutation hasn't been detected in the blood.

    Discussion: Genetically analysis of a specific tumor has not yet become a standard part of the examinational and therapeutic algorithm. If an assumption of a worse course of illness and metastasizing--especially to the liver has been proven, the examination of Kras mutation in patients suffering from colorectal carcinoma should lead to the adjustment of their treatment and postoperative dispensarization, or the administration of chemotherapy and radiotherapy at stages when these modalities are not normally applied.

    Rozhledy v chirurgii : mesicnik Ceskoslovenske chirurgicke spolecnosti 2008;87;1;32-7

  • Molecular changes of epidermal growth factor receptor (EGFR) and KRAS and their impact on the clinical outcomes in surgically resected adenocarcinoma of the lung.

    Kim YT, Kim TY, Lee DS, Park SJ, Park JY, Seo SJ, Choi HS, Kang HJ, Hahn S, Kang CH, Sung SW and Kim JH

    Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Center, Seoul, Republic of Korea. ytkim@snu.ac.kr

    Recent studies have reported that clinical response to epidermal growth factor receptor (EGFR) inhibitors is associated with somatic changes of EGFR in the advanced stage of lung cancer. However, there is no clear data demonstrating whether such molecular changes of EGFR per se can affect the clinical outcome of early stage cancer after surgical resection. DNA mutations of EGFR and KRAS were investigated in 71 adenocarcinoma patients who received surgical resection. Fluorescence in situ hybridization (FISH) of EGFR gene amplification was performed in 48 samples. We detected EGFR mutations in 25 patients (35.2%). EGFR mutation was more frequently found in cases with BAC features (13/22 (59.1%):13/49 (26.5%); p=0.008) and in non-smokers (19/41 (46.3%):7/30 (23.3%); p=0.047). However, the EGFR mutation was not associated with age, gender, or clinical stage. The amplification of EGFR copy was frequently observed in the female gender (12/29 (41.4%):3/19 (15.8%); p=0.061) and in the advanced stage (> or =Stage IIIA, 9/19 (47.4%):6/29 (20.7%); p=0.051). KRAS mutations were present in five patients (7.0%) and none of them showed EGFR mutation. KRAS mutations (p=0.000), male gender (p=0.001), absence of BAC feature (p=0.003), advanced stage (p=0.039), and smoking history (p=0.030) were poor prognostic factors for overall survival, whereas EGFR mutation (p=0.184) and amplification (p=0.756) were not. The presence of EGFR mutation was not a prognostic factor of the clinical outcome of early lung cancer after surgical resection. This result provides an important message for the protocol design of future trials of EGFR inhibitors in early lung cancer. As the KRAS mutation was a poor prognostic factor and it presents reciprocally with EGFR mutation, KRAS mutation should be investigated in such trials. DNA mutations of EGFR and KRAS were investigated in 71 adenocarcinoma patients who received surgical resection. Whereas KRAS mutation was a poor prognostic factor, EGFR mutation was not, and its presence per se did not affect the clinical outcome of early lung cancer after surgical resection.

    Lung cancer (Amsterdam, Netherlands) 2008;59;1;111-8

  • Mutations of FLT3, NRAS, KRAS, and PTPN11 are frequent and possibly mutually exclusive in high hyperdiploid childhood acute lymphoblastic leukemia.

    Paulsson K, Horvat A, Strömbeck B, Nilsson F, Heldrup J, Behrendtz M, Forestier E, Andersson A, Fioretos T and Johansson B

    Department of Clinical Genetics, University Hospital, Lund, Sweden.

    Although it has been suggested that mutations of the FLT3, NRAS, KRAS, and PTPN11 genes are particularly frequent in high hyperdiploid (>50 chromosomes) pediatric acute lymphoblastic leukemias (ALLs), this has as yet not been confirmed in a large patient cohort. Furthermore, it is unknown whether mutations of these genes coexist in hyperdiploid cases. We performed mutation analyses of FLT3, NRAS, KRAS, and PTPN11 in a consecutive series of 78 high hyperdiploid ALLs. Twenty-six (33%) of the cases harbored a mutation, comprising six activating point mutations and one internal tandem duplication of FLT3 (7/78 cases; 9.0%), eight codon 12, 13, or 61 NRAS mutations (8/78 cases; 10%), five codon 12 or 13 KRAS mutations (5/78 cases, 6.4%), and seven exon 3 or 13 PTPN11 mutations (7/78 cases; 9.0%). No association was seen between the presence of a mutation in FLT3, NRAS, KRAS, or PTPN11 and gender, age, white blood cell count, or relapse, suggesting that they do not confer a negative prognostic impact. Only one case harbored mutations in two different genes, suggesting that mutations of these four genes are generally mutually exclusive. In total, one third of the cases harbored a FLT3, NRAS, KRAS, or PTPN11 mutation, identifying the RTK-RAS signaling pathway as a potential target for novel therapies of high hyperdiploid pediatric ALLs.

    Genes, chromosomes & cancer 2008;47;1;26-33

  • Characterization of K-ras gene mutations in association with mucinous hypersecretion in intraductal papillary-mucinous neoplasms.

    Kobayashi N, Inamori M, Fujita K, Fujisawa T, Fujisawa N, Takahashi H, Yoneda M, Abe Y, Kawamura H, Shimamura T, Kirikoshi H, Kubota K, Sakaguchi T, Saito S, Saubermann LJ and Nakajima A

    Gastroenterology Division, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan.

    Intraductal papillary-mucinous neoplasms (IPMNs) of the pancreas have a favorable prognosis. However, invasive ductal carcinomas of the pancreas show a rapid progression. The aim of this study was to investigate gene mutations in pure pancreatic juice from IPMN patients and to define these genetic mutations in relation to the histopathological and clinical features of IPMNs.

    Methods: Twenty-two patients with IPMN, 21 patients with ductal carcinoma, and 20 patients with normal pancreas or chronic pancreatitis were recruited for this study. We measured the main pancreatic duct's largest diameter and the maximum size of a dilated branch was assessed by ultrasonography or endoscopic ultrasonography. Pure pancreatic juice was collected and was investigated for K-ras, p16, and p53 mutations.

    Results: Mutant K-ras gene was detected in 13 of the 22 patients (59.1%) with IPMNs. Different kinds of mutations were detected in the same patient in 4 cases. In the 13 patients with mutant K-ras gene, the diameter of the most dilated part of the main pancreatic duct was 2-8 mm (average, 4.5 mm) and in 7 patients with wild-type K-ras gene, the diameter was 2-5 mm (average, 2.7 mm). There was a significant difference in the diameter of the main pancreatic duct between patients with and without the mutant K-ras gene (P = 0.0323).

    Conclusions: The incidence of K-ras mutation may be associated with the hypersecretion of mucin.

    Journal of hepato-biliary-pancreatic surgery 2008;15;2;169-77

  • Comprehensive biostatistical analysis of CpG island methylator phenotype in colorectal cancer using a large population-based sample.

    Nosho K, Irahara N, Shima K, Kure S, Kirkner GJ, Schernhammer ES, Hazra A, Hunter DJ, Quackenbush J, Spiegelman D, Giovannucci EL, Fuchs CS and Ogino S

    Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA.

    Background: The CpG island methylator phenotype (CIMP) is a distinct phenotype associated with microsatellite instability (MSI) and BRAF mutation in colon cancer. Recent investigations have selected 5 promoters (CACNA1G, IGF2, NEUROG1, RUNX3 and SOCS1) as surrogate markers for CIMP-high. However, no study has comprehensively evaluated an expanded set of methylation markers (including these 5 markers) using a large number of tumors, or deciphered the complex clinical and molecular associations with CIMP-high determined by the validated marker panel. METHOLODOLOGY/PRINCIPAL FINDINGS: DNA methylation at 16 CpG islands [the above 5 plus CDKN2A (p16), CHFR, CRABP1, HIC1, IGFBP3, MGMT, MINT1, MINT31, MLH1, p14 (CDKN2A/ARF) and WRN] was quantified in 904 colorectal cancers by real-time PCR (MethyLight). In unsupervised hierarchical clustering analysis, the 5 markers (CACNA1G, IGF2, NEUROG1, RUNX3 and SOCS1), CDKN2A, CRABP1, MINT31, MLH1, p14 and WRN were generally clustered with each other and with MSI and BRAF mutation. KRAS mutation was not clustered with any methylation marker, suggesting its association with a random methylation pattern in CIMP-low tumors. Utilizing the validated CIMP marker panel (including the 5 markers), multivariate logistic regression demonstrated that CIMP-high was independently associated with older age, proximal location, poor differentiation, MSI-high, BRAF mutation, and inversely with LINE-1 hypomethylation and beta-catenin (CTNNB1) activation. Mucinous feature, signet ring cells, and p53-negativity were associated with CIMP-high in only univariate analysis. In stratified analyses, the relations of CIMP-high with poor differentiation, KRAS mutation and LINE-1 hypomethylation significantly differed according to MSI status.

    Conclusions: Our study provides valuable data for standardization of the use of CIMP-high-specific methylation markers. CIMP-high is independently associated with clinical and key molecular features in colorectal cancer. Our data also suggest that KRAS mutation is related with a random CpG island methylation pattern which may lead to CIMP-low tumors.

    Funded by: NCI NIH HHS: K07 CA122826, P01 CA055075, P01 CA087969, P01 CA55075, P01 CA87969, P50 CA127003

    PloS one 2008;3;11;e3698

  • Gene expression deregulation by KRAS G12D and G12V in a BRAF V600E context.

    Monticone M, Biollo E, Maffei M, Donadini A, Romeo F, Storlazzi CT, Giaretti W and Castagnola P

    Centro Biotecnologie Avanzate, Genova, Italy. massimiliano.monticone@cba-biotecnologie.it

    Background: KRAS and BRAF mutations appear of relevance in the genesis and progression of several solid tumor types but the co-occurrence and interaction of these mutations have not yet been fully elucidated. Using a microsatellite stable (MSS) colorectal cancer (CRC) cell line (Colo741) having mutated BRAF and KRASWT, we also aimed to investigate the KRAS-BRAF interaction. Gene expression profiles for control KRASWT, KRAS G12V and KRAS G12D transfected cells were obtained after cell clone selection and RT-PCR screening. Extensive qPCR was performed to confirm microarray data.

    Results: We found that the KRAS G12V state deregulated several genes associated to cell cycle, apoptosis and nitrogen metabolism. These findings indicated a reduced survival and proliferation with respect to the KRASWT state. The KRAS G12D state was, instead, characterized by several other distinct functional changes as for example those related to chromatin organization and cell-cell adhesion without affecting apoptosis related genes.

    Conclusion: These data predict that the G12D mutation may be more likely selected in a BRAF mutated context. At the same time, the presence of the KRAS G12V mutation in the cells escaping apoptosis and inducing angiogenesis via IL8 may confer a more aggressive phenotype. The present results get along with the observations that CRCs with G12V are associated with a worse prognosis with respect to the WT and G12D states and may help identifying novel CRC pathways and biomarkers of clinical relevance.

    Molecular cancer 2008;7;92

  • Histopathological features of patients with chronic pancreatitis due to mutations in the PRSS1 gene: evaluation of BRAF and KRAS2 mutations.

    Felderbauer P, Stricker I, Schnekenburger J, Bulut K, Chromik AM, Belyaev O, Muller CA, Uhl W, Tannapfel A and Schmidt WE

    Department of Medicine I, St. Josef Hospital, Ruhr University School of Medicine, Bochum, Germany. peter.felderbauer@rub.de

    Hereditary pancreatitis (HP) is a rare cause of chronic pancreatitis (CP; 1%) and more than 25 mutations in the PRSS1 gene have been detected. HP patients with the p.R122H mutation have a 35% lifetime risk of developing pancreatic cancer, but the oncogenetic process remains unknown. We have investigated the histopathological features and frequency of BRAF and KRAS2 mutations in 2 patients with PRSS1 mutations (p.A121T, p.R122H) and patients with CP (n = 11).

    Methods: Pancreatic tissue was stained with hematoxylin-eosin and examined by light microscopy. Mutational analysis of the BRAF (exon 5, 11) and KRAS2 (exon 1) genes was performed using PCR and direct DNA sequencing.

    Results: Histopathological features revealed similar results in both patients, pancreata showed strong fibrosis and ducts with signs of distortion, irregular size and noticeable dilatations. We identified one BRAF mutation (p.V600E) in the p.R122H patient and two KRAS2 (p.G12D; p.G12C) mutations in CP controls.

    Conclusions: Our results sustain the knowledge about the clinical phenotype of patients with PRSS1 mutations who have a high risk of pancreatic cancer. Whether the histopathological picture or the BRAF mutation is specific for patients with PRSS1 mutations or plays a specific role in the tumorigenesis of patients with HP needs to be further evaluated.

    Digestion 2008;78;1;60-5

  • K-RAS and P53 mutations in association with COX-2 and hTERT expression and clinico-pathological status of NSCLC patients.

    Strazisar M, Rott T and Glavac D

    Department of Molecular Genetics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.

    We evaluated the occurrence of mutations in P53, K-RAS, COX-2, expression of COX-2 and hTERT and relations among clinicopathological signs. P53 mutations were identified in 34.4% of tumours, the majority of them occurring in SCC (squamous cell carcinoma, 55.6%). K-RAS was mutated in 12.2% of NSCLC tumours, the majority of the mutations being found in ADC (adenocarcinoma, 27.0%). Mutational screening detected three different COX-2 mutations and five different P53 mutations, published for the first time. With RT-PCR we observed that the expression of the tested genes, hTERT and COX-2, was highly significant for ADC (p<0.01) and SCC (p<0.05). Statistical analysis of the combined results revealed significant correlation between expression of COX-2 and hTERT (p<0.001), hTERT expression and staging (p<0.05) and survival (p<0.01). A positive correlation between COX-2 expression and K-RAS mutation (p<0.05) was also observed. This study provides insight into associations between the analysed biomarkers and the clinical-pathological data of the patients.

    Disease markers 2008;25;2;97-106

  • [K-ras mutations detection in paraaortic lymph nodes and its prognostic value after the surgical treatment of pancreas cancer].

    Agaev BA, Muslimov GF, Iagublu VSh and Babaeva NR

    Survival after surgery of pancreas carcinoma is still poor. Despite an apparently curative resection, tumor rapidly recur. Thus, the arsenal of diagnostic means should be enriched by sensitive methods to detect the minimal residual disease. The frequency of micrometastases in corresponding paraortic lymph nodes after an apparently curative operation was detected using routine histological, immunohistological and polymerase chain reaction for mutated K-ras methods. Tumor tissue was used for the control. 3 cases out of 69 revealed a positive tumor histological reaction, and 5--immunohistological staining. K-ras mutations are detected in 42 (61%) patients, 12 (17%) of those revealed a positive tumor reaction. Only one patient of a control group showed K-ras mutation. All K-ras positive patients revealed a poor survival prognosis and had a tumor relapse after resection.

    Khirurgiia 2008;9;64-9

  • KRAS mutation profile in colorectal carcinoma and novel mutation--internal tandem duplication in KRAS.

    Wójcik P, Kulig J, Okoń K, Zazula M, Moździoch I, Niepsuj A and Stachura J

    Chair and Department of Pathomorphology, Collegium Medicum, Jagiellonian University, Kraków. piotr.wojcik@uj.edu.pl

    Oncogenic KRAS mutations are associated with resistance to anti-EGFR therapy in colorectal carcinoma. Since anti-EGFR monoclonal antibodies are employed in clinical practice in advanced colorectal cancer, KRAS mutations have become an important predictor of therapy outcome. Mutational analysis of KRAS was performed on 163 adenocarcinoma samples. Exons 1-3 of KRAS were analyzed using SSCP and sequencing. Fifty seven (35%) carcinomas had missense point mutations in one of codons 12, 13, 59, 61, 117. In accordance with the published data, missense mutations in codons 12 (66%) and 13 (22%) were the most frequent. Mutations in codons 59 and 117 occurred with the same frequency as in codon 61. The only detected insertion occurred in exon 2. 15-bp insertion resulted in tandem duplication of codons 62-66. Presumably, 5 additional amino acids affected switch II conformation and sustained Ras activity due to decreased GTP hydrolysis. We report this unusual new type mutation.

    Polish journal of pathology : official journal of the Polish Society of Pathologists 2008;59;2;93-6

  • Mutations of RAS gene family in specimens of bladder cancer.

    Karimianpour N, Mousavi-Shafaei P, Ziaee AA, Akbari MT, Pourmand G, Abedi A, Ahmadi A and Afshin Alavi H

    Institute of Biochemistry and Biophysics, Tehran University, Tehran, Iran.

    Introduction: Studies have shown different types of RAS mutations in human bladder tumors with a wide range of mutation frequencies in different patient populations. This study aimed to assess the frequency of specific-point mutations in the RAS gene family of a group of Iranian patients with bladder cancer.

    We examined the tumor specimens of 35 consecutive patients with transitional cell carcinoma. The DNA samples were evaluated for the occurrence of HRAS, KRAS, and NRAS activation using a polymerase chain reaction-restriction fragment length polymorphism technique.

    Results: None of the patients had mutations in the RAS gene family "hot spots" including codons 12, 13, and 61.

    Conclusion: We failed to find RAS mutations in our bladder tumor samples. These observations may reflect the involvement of different etiological factors in the induction of bladder tumor of which RAS mutation might not be present in all populations.

    Urology journal 2008;5;4;237-42

  • PTPN11, SOS1, KRAS, and RAF1 gene analysis, and genotype-phenotype correlation in Korean patients with Noonan syndrome.

    Ko JM, Kim JM, Kim GH and Yoo HW

    Department of Pediatrics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.

    After 2006, germline mutations in the KRAS, SOS1, and RAF1 genes were reported to cause Noonan syndrome (NS), in addition to the PTPN11 gene, and now we can find the etiology of disease in approximately 60-70% of NS cases. The aim of this study was to assess the correlation between phenotype and genotype by molecular analysis of the PTPN11, SOS1, KRAS, and RAF1 genes in 59 Korean patients with NS. We found disease-causing mutations in 30 (50.8%) patients, which were located in the PTPN11 (27.1%), SOS1 (16.9%), KRAS (1.7%), and RAF1 (5.1%) genes. Three novel mutations (T59A in PTPN11, K170E in SOS1, S259T in RAF1) were identified. The patients with PTPN11 mutations showed higher prevalences of patent ductus arteriosus and thrombocytopenia. The patients with SOS1 mutations had a lower prevalence of delayed psychomotor development. All patients with RAF1 mutations had hypertrophic cardiomyopathy. Typical facial features and auxological parameters were, on statistical analysis, not significantly different between the groups. The molecular defects of NS are genetically heterogeneous and involve several genes other than PTPN11 related to the RAS-MAPK pathway.

    Journal of human genetics 2008;53;11-12;999-1006

  • siRNA targeting against EGFR, a promising candidate for a novel therapeutic application to lung adenocarcinoma.

    Yamanaka S, Gu Z, Sato M, Fujisaki R, Inomata K, Sakurada A, Inoue A, Nukiwa T, Kondo T and Horii A

    Department of Molecular Pathology, Tohoku University School of Medicine, Sendai, Japan.

    Objective: To understand the molecular pathogenesis of lung cancer and to establish a novel therapeutic application, we examined the genetic alterations in lung cancer, and studied the effects of gefitinib and siRNA-mediated knockdown of EGFR on lung cancer.

    Methods: We analyzed mutations in EGFR, KRAS, TP53, and ERBB2 in 198 surgically resected lung cancer specimens. We then analyzed the effects of gefitinib and siRNA treatment on lung adenocarcinoma cell lines.

    Results: Mutations in EGFR were found only in adenocarcinoma (35 of 106 adenocarcinoma), mainly in females (73%). Mutually exclusive mutations of EGFR and KRAS genes were observed. Mutations of EGFR were well associated with a positive response to gefitinib. Cells with EGFR mutations were very sensitive to gefitinib as well as siRNA-mediated knockdown of EGFR, those with KRAS mutations responded poorly, and those without mutations of KRAS and EGFR showed moderate responses to both treatments.

    Conclusions: Our present results imply that (1) mutation analyses of EGFR and KRAS provide valuable information about whether or not to apply treatments targeting against EGFR and the selection of dosage for such treatments, and (2) siRNA-mediated knockdown is effective in lung adenocarcinomas with EGFR mutation, probably in those with resistance to gefitinib by acquired mutation in EGFR.

    Pathobiology : journal of immunopathology, molecular and cellular biology 2008;75;1;2-8

  • The differentially mutational spectra of the APC, K-ras, and p53 genes in sporadic colorectal cancers from Taiwanese patients.

    Wang JY, Hsieh JS, Lu CY, Yu FJ, Wu JY, Chen FM, Huang CJ and Lin SR

    Department of Surgery, Kaohsiung Medical University Hospital, Taiwan.

    Adenomatous polyposis coli (APC), K-ras and p53 gene mutations are the most common genetic alterations present in colorectal cancer (CRC). The aim of this study was to analyze tumor mutation frequencies and spectra in a large cohort of Taiwanese patients with CRC.

    Methodology: APC, K-ras, and p53 gene mutations in primary tumor tissues and their paired normal tissues of 123 CRC patients were detected by polymerase chain reaction-single strand conformation polymorphism analysis, followed by direct sequencing.

    Results: Of these 123 CRC patients, 43.1%, 44.7%, 35% of tumor tissue specimens presented mutations in APC, K-ras, and p53 genes, respectively. Overall, gene mutations in APC, K-ras and/or p53 were present in 78% (96/123) of tumor tissues. Among 96 CRC patients harboring gene mutations, 49 (51%) contained mutations of at least two different genes and 47 (49%) contained mutations of one gene only. The most common combination of gene mutations was APC and K-ras mutations (21.9%), followed by K-ras and p53 mutations (12.5%) and then APC and p53 mutations (10.4%). In addition, there were only 6.3% (6/96) of tumor tissues from CRC patients simultaneously containing mutations of APC, K-ras and p53 genes. The most common mutation spectrum of these genes was missense mutations, at a frequency of 38.8%, 92.7% and 70.5% for APC, K-ras and p53 genes, respectively.

    Conclusions: These data support that the frequencies and patterns of somatic mutation of the APC, Kras and p53 genes in CRCs are considerably variable and distinct among populations, for which the interaction between exogenous environmental factors and endogenous gene alterations may be important determinants.

    Hepato-gastroenterology 2007;54;80;2259-65

  • Cardio-facio-cutaneous and Noonan syndromes due to mutations in the RAS/MAPK signalling pathway: genotype-phenotype relationships and overlap with Costello syndrome.

    Nava C, Hanna N, Michot C, Pereira S, Pouvreau N, Niihori T, Aoki Y, Matsubara Y, Arveiler B, Lacombe D, Pasmant E, Parfait B, Baumann C, Héron D, Sigaudy S, Toutain A, Rio M, Goldenberg A, Leheup B, Verloes A and Cavé H

    Department of Genetics, AP-HP, Hôpital Robert Debré, Paris, France.

    Cardio-facio-cutaneous (CFC) syndrome, Noonan syndrome (NS), and Costello syndrome (CS) are clinically related developmental disorders that have been recently linked to mutations in the RAS/MEK/ERK signalling pathway. This study was a mutation analysis of the KRAS, BRAF, MEK1 and MEK2 genes in a total of 130 patients (40 patients with a clinical diagnosis of CFC, 20 patients without HRAS mutations from the French Costello family support group, and 70 patients with NS without PTPN11 or SOS1 mutations). BRAF mutations were found in 14/40 (35%) patients with CFC and 8/20 (40%) HRAS-negative patients with CS. KRAS mutations were found in 1/40 (2.5%) patients with CFC, 2/20 (10%) HRAS-negative patients with CS and 4/70 patients with NS (5.7%). MEK1 mutations were found in 4/40 patients with CFC (10%), 4/20 (20%) HRAS-negative patients with CS and 3/70 (4.3%) patients with NS, and MEK2 mutations in 4/40 (10%) patients with CFC. Analysis of the major phenotypic features suggests significant clinical overlap between CS and CFC. The phenotype associated with MEK mutations seems less severe, and is compatible with normal mental development. Features considered distinctive for CS were also found to be associated with BRAF or MEK mutations. Because of its particular cancer risk, the term "Costello syndrome" should only be used for patients with proven HRAS mutation. These results confirm that KRAS is a minor contributor to NS and show that MEK is involved in some cases of NS, demonstrating a phenotypic continuum between the clinical entities. Although some associated features appear to be characteristic of a specific gene, no simple rule exists to distinguish NS from CFC easily.

    Journal of medical genetics 2007;44;12;763-71

  • Expression of epidermal growth factor receptor, but not K-RAS mutations, is present in congenital cystic airway malformation/congenital pulmonary airway malformation.

    Guo H, Cajaiba MM, Borys D, Gutierrez MC, Yee H, Drut RM, Drut R, Askin F, Reyes-Múgica M and Greco MA

    Division of Pediatric Pathology, Department of Pathology, New York University School of Medicine, Bellevue Hospital Center, New York, NY 10016, USA.

    Congenital cystic airway malformation/congenital pulmonary airway malformation (CCAM/CPAM) of the lung is a rare but well-described malformative lesion of pulmonary parenchyma characterized by the abnormal maturation of airways along with an increase in terminal respiratory structures, resulting in cysts of variable sizes. Five types have been classified based on morphological analysis. Although the etiology of the lesion is still unclear, recent data suggest that bronchial atresia is a predisposing/associated anomaly. A described association between type 1 CCAM/CPAM and bronchioloalveolar carcinoma suggests that type 1 CCAM/CPAM may predispose to malignant transformation by as yet unidentified tumorigenic mechanisms. Here we studied epidermal growth factor receptor (EGFR) and K-RAS oncogene, 2 biological markers closely associated with tumorigenesis and altered in many types of tumors, including lung carcinomas. For this purpose, we used immunohistochemistry and gene sequencing in paraffin-embedded tissue. Our results demonstrate expression of EGFR in types 1 and 3 CCAM/CPAM, with a distinctive distribution and intensity, compared with that of type 2. Of special interest, mucinous areas in 2 cases of type 1 CCAM/CPAM lacked EGFR expression, whereas adjacent epithelial cystic linings were strongly positive. This supports the hypothesis that mucinous differentiation in CCAM/CPAM, always present in cases with malignant transformation, could be related to other molecular pathways. The K-RAS gene was screened for mutations usually found in lung carcinomas; however, no mutations were present in any of the studied samples. These findings support the notion that EGFR may play an important role in the pathogenesis and phenotype of CCAM/CPAM.

    Human pathology 2007;38;12;1772-8

  • RbAp48 regulates cytoskeletal organization and morphology by increasing K-Ras activity and signaling through mitogen-activated protein kinase.

    Scuto A, Zhang H, Zhao H, Rivera M, Yeatman TJ, Jove R and Torres-Roca JF

    Division of Molecular Medicine, City of Hope Beckman Research Institute, National Medical Center, Duarte, California, USA.

    RbAp48 is a WD-40 protein that plays an important role in chromatin metabolism and regulates Ras signaling. Here, we report that RbAp48 is involved in the regulation of cytoskeletal organization, a novel function. First, we show that transfection of RbAp48 into Hs-578T breast cancer cells (Hs-RbAp48-hi) leads to cell size reduction, a rounded cell shape, decreased cellular protrusions, and a higher nuclear/cytoplasmic ratio. Furthermore, we observed cytoskeletal F-actin organization disruption with loss of actin stress fibers and formation of membranous F-actin rings in Hs-RbAp48-hi cells. These morphologic changes were partially reversed by RbAp48 knockdown. Interestingly, mitogen-activated protein kinase (MAPK) was activated in Hs-RbAp48-hi cells, and this activity was also partly reversed by RbAp48 down-regulation. Furthermore, pharmacologic inhibition of MAPK led to the reappearance of organized actin fibers and focal contacts, suggesting MAPK as the effector pathway. Moreover, we show an increase in total Ras activity in Hs-RbAp48-hi cells with K-Ras-GTP becoming the dominant isoform. This reverted to baseline activity levels on RbAp48 small interfering RNA transfection, thus suggesting a direct role for RbAp48 in Ras regulation. Finally, we tested the model in transformed 3T3-K-Ras-G12V fibroblasts. As expected, RbAp48 knockdown in 3T3-K-Ras-hi fibroblasts resulted in reappearance of an organized cytoskeleton and shutdown of K-Ras activity. In conclusion, our data support a model whereby RbAp48 regulates cellular morphology and cytoskeletal organization by increasing K-Ras activity and signaling through MAPK.

    Funded by: NCI NIH HHS: K08CA108926-03, R01 CA055652

    Cancer research 2007;67;21;10317-24

  • Biochemical and functional characterization of germ line KRAS mutations.

    Schubbert S, Bollag G, Lyubynska N, Nguyen H, Kratz CP, Zenker M, Niemeyer CM, Molven A and Shannon K

    Department of Pediatrics, University of California, 513 Parnassus Avenue, HSE 302, San Francisco, California 94143, USA.

    Germ line missense mutations in HRAS and KRAS and in genes encoding molecules that function up- or downstream of Ras in cellular signaling networks cause a group of related developmental disorders that includes Costello syndrome, Noonan syndrome, and cardiofaciocutaneous syndrome. We performed detailed biochemical and functional studies of three mutant K-Ras proteins (P34R, D153V, and F156L) found in individuals with Noonan syndrome and cardiofaciocutaneous syndrome. Mutant K-Ras proteins demonstrate a range of gain-of-function effects in different cell types, and biochemical analysis supports the idea that the intrinsic Ras guanosine nucleotide triphosphatase (GTPase) activity, the responsiveness of these proteins to GTPase-activating proteins, and guanine nucleotide dissociation all regulate developmental programs in vivo.

    Funded by: NCI NIH HHS: R01 CA104282, R37 CA072614, R37 CA72614

    Molecular and cellular biology 2007;27;22;7765-70

  • High-degree tumor budding and podia-formation in sporadic colorectal carcinomas with K-ras gene mutations.

    Prall F and Ostwald C

    Institute of Pathology, University of Rostock, Rostock, Germany. friedrich.prall@med.uni-rostock.de

    In vitro ras activation enhances the epithelial-mesenchymal transition of colorectal carcinoma cells. But ras effects are known to be highly dependent on cell types and the tissue context. Therefore, this study was made to test the hypothesis that in clinical colorectal carcinoma specimens, aggressive invasion phenotypes, specifically tumor budding and podia formation, would correlate with K-ras gene mutations. In a series of 95 clinically sporadic primary colorectal carcinomas collected ad hoc, tumor budding and podia formation were counted using pan-cytokeratin immunohistochemistry, and K-ras gene mutations in codons 12 and 13 were determined. Consistent with the hypothesis, tumor budding and podia formation were observed to be significantly higher in the 32 (34.7%) of the tumors with K-ras gene mutations (29 mutations in codon 12, 3 in codon 13), and this correlation was observed independent of the patterns of invasion (expansive versus infiltrative). Microsatellite status, numbers of losses of heterozygosity, adenomatous polyposis coli and p53 gene mutations, and degree of promoter methylations (CIMP status) were not associated with K-ras gene mutations. Besides their effects on the tumor cell cycles, oncogenic K-ras gene mutations in colorectal carcinomas could be important for aggressive tumor invasion. This may be important in metastasizing disease and could provide a rationale for developing drugs that interrupt ras-signaling cascades.

    Human pathology 2007;38;11;1696-702

  • RAS/ERK modulates TGFbeta-regulated PTEN expression in human pancreatic adenocarcinoma cells.

    Chow JY, Quach KT, Cabrera BL, Cabral JA, Beck SE and Carethers JM

    Division of Gastroenterology, Department of Medicine, University of California, San Diego, MC 0063, 9500 Gilman Drive, La Jolla, CA 92093-0063, USA.

    Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is rarely mutated in pancreatic cancers, but its regulation by transforming growth factor (TGF)-beta might mediate growth suppression and other oncogenic actions. Here, we examined the role of TGFbeta and the effects of oncogenic K-RAS/ERK upon PTEN expression in the absence of SMAD4. We utilized two SMAD4-null pancreatic cell lines, CAPAN-1 (K-RAS mutant) and BxPc-3 (WT-K-RAS), both of which express TGFbeta surface receptors. Cells were treated with TGFbeta1 and separated into cytosolic/nuclear fractions for western blotting with phospho-SMAD2, SMAD 2, 4 phospho-ATP-dependent tyrosine kinases (Akt), Akt and PTEN antibodies. PTEN mRNA levels were assessed by reverse transcriptase-polymerase chain reaction. The MEK1 inhibitor, PD98059, was used to block the downstream action of oncogenic K-RAS/ERK, as was a dominant-negative (DN) K-RAS construct. TGFbeta increased phospho-SMAD2 in both cytosolic and nuclear fractions. PD98059 treatment further increased phospho-SMAD2 in the nucleus of both pancreatic cell lines, and DN-K-RAS further improved SMAD translocation in K-RAS mutant CAPAN cells. TGFbeta treatment significantly suppressed PTEN protein levels concomitant with activation of Akt by 48 h through transcriptional reduction of PTEN mRNA that was evident by 6 h. TGFbeta-induced PTEN suppression was reversed by PD98059 and DN-K-RAS compared with treatments without TGFbeta. TGFbeta-induced PTEN expression was inversely related to cellular proliferation. Thus, oncogenic K-RAS/ERK in pancreatic adenocarcinoma facilitates TGFbeta-induced transcriptional down-regulation of the tumor suppressor PTEN in a SMAD4-independent manner and could constitute a signaling switch mechanism from growth suppression to growth promotion in pancreatic cancers.

    Funded by: NCI NIH HHS: CA90231; NHLBI NIH HHS: T32-HL07212; NIDDK NIH HHS: DK067287, K01 DK073090-01A1, K01-DK073090, R01 DK067287, R01 DK067287-02, R24 DK080506-01

    Carcinogenesis 2007;28;11;2321-7

  • Single base instability is promoted in vulvar lichen sclerosus.

    Tapp RA, Feng J, Jones JW, Carlson JA and Wilson VL

    Department of Veterinary Comparative Biomedical Sciences, Louisiana State University, Baton Rouge, Louisiana, USA.

    Single base substitution mutations in codons 248 and 273 of TP53 and codon 12 Kirsten-ras (KRAS) are commonly found in human carcinomas. To determine whether these mutations also occur in normal and inflamed tissues from which carcinomas arise, we utilized the ultra-sensitive polymerase chain reaction/restriction endonuclease/ligase chain reaction mutation assay. Ninety samples of genital skin, including lichen sclerosus (LS) affected skin, adjacent normal and non-adjacent normal, were assayed. Mutations were detected in 103 of 349 assays and consisted of KRAS G34A, G34T, G35A, and TP53 C742T, G818C, C817T, and G818A mutations. Mutant prevalence varied from 1 to 20 per 10(6) wild-type cells. Mutations occurred significantly more frequently in LS (78/224 (35%)) than adjacent normal (20/88 (23%)) and non-adjacent normal genital skin (5/38 (13%)). KRAS G34A mutation was relatively common to all classes of specimen, whereas TP53 gene C742T and G818C mutations were significantly more frequent in LS than normal genital skin. In matched samples, immunohistochemistry evaluation of p53 protein expression revealed the presence of epidermal p53 clones in LS whose presence and number significantly correlated with the presence of TP53 C742T and G818C mutations. Based on these results, it appears oncogenic point mutations occur in normal genital skin, and are selected for in LS.

    The Journal of investigative dermatology 2007;127;11;2563-76

  • Dietary fat and risk of colon and rectal cancer with aberrant MLH1 expression, APC or KRAS genes.

    Weijenberg MP, Lüchtenborg M, de Goeij AF, Brink M, van Muijen GN, de Bruïne AP, Goldbohm RA and van den Brandt PA

    Department of Epidemiology, Nutrition and Toxicology Research Institute Maastricht, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands mp.weijenberg@epid.unimaas.nl

    Objective: To investigate baseline fat intake and the risk of colon and rectal tumors lacking MLH1 (mutL homolog 1, colon cancer, nonpolyposis type 2) repair gene expression and harboring mutations in the APC (adenomatous polyposis coli) tumor suppressor gene and in the KRAS (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) oncogene.

    Methods: After 7.3 years of follow-up of the Netherlands Cohort Study (n = 120,852), adjusted incidence rate ratios (RR) and 95% confidence intervals (CI) were computed, based on 401 colon and 130 rectal cancer patients.

    Results: Total, saturated and monounsaturated fat were not associated with the risk of colon or rectal cancer, or different molecular subgroups. There was also no association between polyunsaturated fat and the risk of overall or subgroups of rectal cancer. Linoleic acid, the most abundant polyunsaturated fatty acid in the diet, was associated with increased risk of colon tumors with only a KRAS mutation and no additional truncating APC mutation or lack of MLH1 expression (RR = 1.41, 95% CI 1.18-1.69 for one standard deviation (i.e., 7.5 g/day) increase in intake, p-trend over the quartiles of intake <0.001). Linoleic acid intake was not associated with risk of colon tumors without any of the gene defects, or with tumors harboring aberrations in either MLH1 or APC.

    Conclusion: Linoleic acid intake is associated with colon tumors with an aberrant KRAS gene, but an intact APC gene and MLH1 expression, suggesting a unique etiology of tumors with specific genetic aberrations.

    Cancer causes & control : CCC 2007;18;8;865-79

  • P21WAF1/CIP1 expression in colorectal carcinomas is related to Kras mutations and prognosis.

    Mitomi H, Ohkura Y, Fukui N, Kanazawa H, Kishimoto I, Nakamura T, Yokoyama K, Sada M, Kobayashi K, Tanabe S and Saigenji K

    Department of Clinical Research Laboratory (Pathology Division), National Hospital Organization Sagamihara Hospital, Sakura-dai, Sagamihara, Kanagawa, Japan. mitomi@sagamihara-hosp.gr.jp

    P21WAF1/CIP1 is a cyclin-dependent kinase inhibitor activated by p53 to produce cell cycle arrest. A consensus has not been reached concerning the prognostic value of p21WAF1/CIP1 expression in colorectal cancers.

    P21WAF1/CIP1 expression was determined immunohistochemically in a series of 211 cases of colorectal carcinomas, together with its relation to p53, bcl-2, cell turnover (as assessed by Ki67 expression and apoptotic counts) and the Kras gene status. The expression of p21WAF1/CIP1 was also compared with reference to clinicopathological parameters and patient survival.

    Results: The median value for nuclear p21WAF1/CIP1 expression was 31% (interquartile range, 13-47%) and the fraction of cases considered to be high expressers (>20%) was 66%. Expression of p21WAF1/CIP1 was not associated with immunoreactivity for p53 or bcl-2, or cell turnover. P21WAF1/CIP1 high-expressing tumors were more often well differentiated (P<0.001), node-negative (P=0.037), Dukes' B (P=0.027) and Kras gene-mutated cases (P=0.04). On univariate analysis, low p21WAF1/CIP1 expressers (<or=20%) had lower cancer-related survival as compared with high expressers (5-year survival, 56 vs. 70%; P=0.042). Lymph node status, liver metastasis and tumor size were also significant predictors. Multivariate analysis revealed lymph node-positive (P<0.001), liver metastasis (P<0.001), and low p21WAF1/CIP1 expression (P=0.017) to be independent predictors of short survival.

    Conclusion: The regulation of p21WAF1/CIP1, independent of p53 or bcl-2 expression, appears to be associated with Kras mutations. The immunohistochemical detection of p21WAF1/CIP11 might thus be used to predict more precise outcome in colorectal cancer patients.

    European journal of gastroenterology & hepatology 2007;19;10;883-9

  • Prevalence of RAS point mutations in papillary thyroid carcinoma; a novel mutation at codon 31 of K-RAS.

    Cyniak-Magierska A, Brzeziańska E, Januszkiewicz-Caulier J, Jarzab B and Lewiński A

    Department of Endocrinology and Metabolic Diseases, Medical University of Lodz, Polish Mother's Memorial Hospital - Research Institute, Lodz, Poland.

    The aim of this study was to assess the incidence of point mutations in RAS oncogenes of papillary thyroid carcinoma (PTC). Tumour specimens were obtained from 29 PTCs. The fragments of exons 1 and 2 of RAS oncogenes family (H- RAS, K- RAS, N- RAS) were amplified and then, point mutations were detected by SSCP and/or by RFLP analysis. Several DNA samples were directly sequenced to confirm the results. Two mutations were found in this study (GAA/CAA at codon 31 of K- RAS and CAA/CAC at codon 61 of N- RAS oncogene). These data confirm the results of previous studies, showing that RAS mutations are more rarely found in PTC than in follicular neoplasms. The influence of a novel mutation at codon 31 of K- RAS oncogene on the development of PTC needs further studies.

    Experimental and clinical endocrinology & diabetes : official journal, German Society of Endocrinology [and] German Diabetes Association 2007;115;9;594-9

  • Changes in gene-expression profiles of colon carcinoma cells induced by wild type K-ras2.

    Li H, Cao HF, Li Y, Zhu ML and Wan J

    Inpatient Department of Special Need Treatment, General Hospital of Chinese PLA, Beijing, China.

    Aim: To further elucidate the possible molecular biological activity of wild type K-ras2 gene by detecting changes in wild type K-ras2 gene-induced gene-expression profiles of colon carcinoma cells using cDNA microarray techniques.

    Methods: Total RNA was isolated from peripheral blood of health volunteers. Reverse transcription of RNA and polymerase chain reaction were used to synthesize wild type K-ras2 cDNA. K-ras2 cDNA fragment was cloned into a T easy vector and sequenced. A eukaryotic expression vector pCI-neo-K-ras2 was constructed and transfected to Caco2 cell line using the liposome method. Finally, mRNA was isolated, reverse-transcribed to cDNA from pCI-neo-K-ras2 or pCI-neo blank vector-transfected Caco cells, and analyzed by cDNA microarray assay.

    Results: Restriction enzyme analysis and DNA sequencing verified that the constructed expression vector was accurate. High-quality RNA was extracted and reverse transcribed to cDNA for microarray assay. Among the 135 genes, the expression was up-regulated in 24 and down-regulated in 121. All these differentially expressed genes were related to cell proliferation, differentiation, apoptosis and signal transduction.

    Conclusion: Differentially expressed genes can be successfully screened from wild type K-ras2-transfected colon carcinoma cells using microarray techniques. The results of our study suggest that wild type K-ras2 is related to the negative regulation of cell proliferation, metabolism and transcriptional control, and provide new clues to the further elucidation of its possible biological activity.

    World journal of gastroenterology 2007;13;34;4620-5

  • Origin and prognostic value of circulating KRAS mutations in lung cancer patients.

    Gautschi O, Huegli B, Ziegler A, Gugger M, Heighway J, Ratschiller D, Mack PC, Gumerlock PH, Kung HJ, Stahel RA, Gandara DR and Betticher DC

    University of California Davis Cancer Center, 4501 X Street, Sacramento, CA 95817, USA. oliver_gautschi@hotmail.com

    Because of the current controversy on the origin and clinical value of circulating KRAS codon 12 mutations in lung cancer, we screened 180 patients using a combined restriction fragment-length polymorphism and polymerase chain reaction (RFLP-PCR) assay. We detected KRAS mutations in 9% plasma samples and 0% matched lymphocytes. Plasma KRAS mutations correlated significantly with poor prognosis. We validated the positive results in a second laboratory by DNA sequencing and found matching codon 12 sequences in blood and tumor in 78% evaluable cases. These results support the notion that circulating KRAS mutations originate from tumors and are prognostically relevant in lung cancer.

    Cancer letters 2007;254;2;265-73

  • Low frequency of p53 and k-ras codon 12 mutations in non-small cell lung carcinoma (NSCLC) tumors and surgical margins.

    Vatan O, Bilaloglu R, Tunca B, Cecener G, Gebitekin C, Egeli U, Yakut T and Urer N

    Department of Biology, Science and Art Faculty, Uludag University, Bursa, Turkey. ovatan@uludag.edu.tr

    Lung cancer is one of the most common cancers and has became a predominant cause of cancer-related death throughout the world. The k-ras codon 12 mutation, which is the most common lung cancer mutation, is found in 15 to 30% of all lung cancers. Furthermore, the p53 gene has a very important role in the biological properties of tumor cells, and it is mutated in about 50% of non-small cell lung cancers. Residual tumor cells remain in surgical margins diagnosed as tumor free by histopathological techniques, and they can play a role in forming any local recurrence. Molecular methods may be exploited that are sensitive enough to detect small numbers of tumor cells.

    Methods: In the present study, we examined p53 gene mutations and k-ras codon 12 mutations from the tumor samples and surgical margins of 34 non-small-cell lung cancer patients. P53 gene mutations were analyzed by single strand conformational polymorphism analysis, heterodublex analysis and DNA sequencing. K-ras codon 12 mutations were analyzed by the mutagenic PCR-restricted fragment length polymorphism method.

    Results: A p53 mutation was detected only in primary tumors of 3 out of 34 patients (8.82%). These mutations were clustered in exon 5. Moreover, a k-ras codon 12 mutation was detected in both the primary tumor and the surgical margin tissues of 2 out of 34 patients (5.88%).

    Conclusions: The detected mutation rate was low, in the range given in the literature. We think that different mechanisms related to other genes and individual genetic differences might play a role in cancer formation in our study group. We believe that molecular studies are necessary to identify biomarkers and to determine genetic alterations in histopathologically normal surgical margins.

    Tumori 2007;93;5;473-7

  • Nras and Kras mutation in Japanese lung cancer patients: Genotyping analysis using LightCycler.

    Sasaki H, Okuda K, Kawano O, Endo K, Yukiue H, Yokoyama T, Yano M and Fujii Y

    Department of Surgery II, Nagoya City University Medical School, Nagoya 467-8601, Japan. hisasaki@med.nagoya-cu.ac.jp

    Activating mutations of Ras gene families have been found in a variety of human malignancies, including lung cancer, suggesting their dominant role in tumorigenesis. Many studies have showed that the Kras gene is activated by point mutations in approximately 15-20% of non-small cell lung cancers (NSCLCs), however, there are only a few reports on Nras mutations in NSCLC. We have genotyped Nras mutation status (n=195) and Kras mutation status (n=190) in surgically treated lung adenocarcinoma cases. The presence or absence of Nras and Kras mutations was analyzed by real-time quantitative polymerase chain reaction (PCR) with mutation-specific sensor and anchor probes. EGFR mutation status at kinase domain has already been reported. Nras mutation was found in 1 of 195 patients. This mutation was a G-to-T transversion, involving the substitution of the normal glycine (GGT) with cystein (TGT) and thought to be a somatic mutation. The patient was male and a smoker. Kras mutant patients (11.1%; 21/190) had a significantly worse prognosis than wild-type patients (p=0.0013). Eighty-two EGFR mutations at kinase domain had exclusively Nras or Kras mutations. Although Nras gene mutation might be one of the mechanisms of oncogenesis of lung adenocarcinoma, this was a very rare event. Further studies are needed to confirm the mechanisms of Nras mutations for the sensitivity of molecular target therapy for lung cancer.

    Oncology reports 2007;18;3;623-8

  • Ras pathway activation in malignant mesothelioma.

    Patel MR, Jacobson BA, De A, Frizelle SP, Janne P, Thumma SC, Whitson BA, Farassati F and Kratzke RA

    Division of Hematology-Oncology-Transplant, Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.

    Introduction: Mutations in Ras family genes are rare in malignant mesothelioma. The role of activation of the Ras signaling pathway in the pathogenesis of mesothelioma is not clear.

    Methods: We studied the activation status of the Ras pathway and the status of other Ras-associated kinases in a panel of human mesothelioma cell lines. In addition, we tested the effect of inhibition of several kinase pathways on mesothelioma cell proliferation. The potential role of kinase signaling on the regulation of cap-dependent translation was also studied.

    Results: In general, Ras-guanosine triphosphate (GTP) was higher in mesothelioma cell lines when compared with a nontransformed mesothelial cell line (LP9). Furthermore, known Ras effectors such as extracellular-regulated kinase 1/2, p38 mitogen-activated protein kinase, and c-Jun N-terminal kinase were found to be active in most of the mesothelioma cell lines tested. Exposure to specific inhibitors of extracellular-regulated kinase 1/2 (U0126) and c-Jun N-terminal kinase (SP600125) significantly decreased the proliferation of H2596 and H2373 cells compared with mock-treated cells. SP600125-mediated c-Jun N-terminal kinase inhibition, but not extracellular-regulated kinase 1/2 inhibition, resulted in a decrease in phosphorylation of 4E-BP1, consequently decreasing cap-dependent activation.

    Conclusions: These experiments provide a rationale for targeting Ras and associated signaling pathways in mesothelioma and also suggest cap-dependent translation as one mechanism by which Ras induces proliferation in this disease.

    Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer 2007;2;9;789-95

  • Patterns of PIK3CA alterations in familial colorectal and endometrial carcinoma.

    Ollikainen M, Gylling A, Puputti M, Nupponen NN, Abdel-Rahman WM, Butzow R and Peltomäki P

    Department of Medical Genetics, University of Helsinki, Helsinki, Finland.

    While the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway is known to be activated in multiple sporadic cancers, the role of this pathway in familial tumors is mostly unknown. We searched for alterations in the catalytic domain of PI3K (PIK3CA), PTEN and KRAS, all of which may contribute to PI3K/AKT pathway activation, in a total of 160-familial colorectal (CRC) and endometrial carcinomas (EC), stratified by the presence vs. absence of germline mutations in DNA mismatch repair (MMR) genes. PIK3CA alterations (consisting of point mutations or low-level amplification, which were mutually exclusive with 1 exception) occurred in 10/70 (14%) of CRCs and 19/90 (21%) of ECs. Within ECs, amplification was significantly associated with the subgroup lacking germline mutations in MMR genes (familial site-specific endometrial cancer) (p = 0.015). Decreased or lost PTEN expression was characteristic of endometrial tumourigenesis (51/81, 63%, in EC compared with 24/62, 39%, in CRC, p = 0.004) and KRAS mutations of colorectal tumourigenesis (19/70, 27% in CRC vs. 9/89, 10%, in EC, p = 0.006) regardless of the MMR gene mutation status. PIK3CA alterations frequently coexisted with PTEN or KRAS changes. Combined with published studies on sporadic tumors, our data broaden the understanding of the role for PI3K pathway genes in human tumorigenesis.

    International journal of cancer. Journal international du cancer 2007;121;4;915-20

  • Involvement of Kruppel-like factor 6 (KLF6) mutation in the development of nonpolypoid colorectal carcinoma.

    Mukai S, Hiyama T, Tanaka S, Yoshihara M, Arihiro K and Chayama K

    Department of Endoscopy, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan.

    Aim: To examine Kruppel-like factor 6 (KLF6) mutations in nonpolypoid-type tumors and alterations of K-ras, p53, and B-raf in relation between mutation and morphologic type, particularly nonpolypoid-type colorectal carcinomas.

    Methods: Fifty-five early nonpolypoid colorectal carcinomas were analyzed. Loss of heterozygosity (LOH) of KLF6 and p53 was determined by microsatellite assay. Mutations of KLF6, K-ras, and B-raf were examined by polymerase chain reaction-single-strand conformation polymorphism followed by direct sequencing. In LOH-positive and/or mutation-positive tumors, multiple (4-7) samples in each tumor were microdissected and examined for genetic alterations. p53 expression was evaluated by immunohistochemistry.

    Results: LOH of KLF6 and p53 was found in 14 of 29 (48.3%) and 14 of 31 (45.2%) tumors, respectively. In 10 of the 14 (71.4%) KLF6 LOH-positive tumors and 9 of the 14 (64.3%) p53 LOH-positive tumors, LOH was found in all of the microdissected samples. In 1 of the 10 (10.0%) KLF6 LOH-positive tumors, a single missense mutation was identified. K-ras and B-raf mutations were found in 5 of 55 (9.1%) and 6 of 55 (10.9%) tumors, respectively. However, these mutations were detected only in subsets of microdissected tumor samples.

    Conclusion: These data suggest that KLF6 and p53 mutations are involved in the development of nonpolypoid colorectal carcinoma, whereas K-ras and B-raf mutations are not.

    World journal of gastroenterology 2007;13;29;3932-8

  • Differences in K-ras and p53 gene mutations among pancreatic adenocarcinomas associated with regional environmental pollution.

    Soliman AS, Lo AC, Banerjee M, El-Ghawalby N, Khaled HM, Bayoumi S, Seifeldin IA, Abdel-Aziz A, Abbruzzese JL, Greenson JK and Hamilton SR

    Department of Epidemiology, University of Michigan School of Public Health, 109 Observatory Street, Ann Arbor, MI 48109, USA. asoliman@umich.edu

    Background: Variations in genetic mutations in pancreatic carcinoma between different geographical regions have not been studied extensively, especially in developing countries where pancreatic cancer is relatively rare.

    Methods: We studied the molecular pathology of 54 pancreatic adenocarcinomas from Egyptian patients residing in a heavily polluted region of the eastern Nile River delta and compared the findings with 45 tumors from patients residing in low-pollution regions.

    Results: Rates of K-ras mutation in codon 12 and of p53 mutation in exons 5-8 were higher in tumors of patients from the high-pollution region as compared with the low-pollution regions (61.5 versus 34.2%, respectively, for K-ras, P = 0.01; 25.9 versus 11.6%, respectively, for p53, P = 0.08). There were also distinct differences in the specific types of K-ras and p53 mutations between the two regions. The ratio of G-to-T k-ras transversion mutation (codon 12) relative to wild-type was significantly higher in tumors from the high-pollution region (0.90) than tumors from the non-pollution site (0.28) (P = 0.03). Relative to tumors with wild-type, the ratio of p53 mutations in exons 5, 7 or 8 to wild-type in tumors from the high-pollution region was significantly higher than the ratio from the non-pollution site (0.28 versus 0.03, P = 0.01). Logistic regression showed that G-to-T transversion mutation in K-ras was predicted by the region of residence of the patients.

    Conclusions: Our study reveals that there are differences in the frequencies and types of K-ras and p53 mutations found in pancreatic adenocarcinomas of patients in high-pollution and low-pollution regions in Egypt and suggests that environmental factors may explain these differences. We speculate that gene-environment interactions in pancreatic carcinogenesis also occur in other populations.

    Funded by: NCI NIH HHS: CA K07 090241, CA46592, P30 CA16672, R03 CA 123715, R03 CA099513-01; PHS HHS: R25 112383

    Carcinogenesis 2007;28;8;1794-9

  • Lifetime history of tobacco consumption and K-ras mutations in exocrine pancreatic cancer.

    Crous-Bou M, Porta M, López T, Jariod M, Malats N, Alguacil J, Morales E, Fernandez E, Corominas JM, Carrato A, Guarner L, Real FX and PANKRAS II Study Group

    Institut Municipal d'Investigació Mèdica, Barcelona, Spain.

    Objectives: We analyzed the relation between mutations in codon 12 of the K-ras oncogene and lifetime consumption of tobacco in patients with exocrine pancreatic cancer (EPC).

    Methods: Incident cases of EPC were prospectively identified and interviewed during hospital admission about smoking and other factors. Exact logistic regression was used to compare EPC cases (N = 107) with and without K-ras mutations (case-case study).

    Results: Mutated cases were nonsignificantly less likely to have been smokers than wild-type cases: the odds ratio adjusted by age and sex was 0.54 (95% confidence interval, 0.10-2.69; P = 0.613). With respect to never smokers, adjusted odds ratios for former and current smokers were 0.79 and 0.36, respectively (P = 0.193). Pack-years smoked, years of smoking, and cigarettes smoked per year also tended to be higher in nonmutated than in mutated cases. Neither age at onset of smoking nor the time between quitting and diagnosis were associated with K-ras.

    Conclusions: Tobacco does not play a major part in the acquisition of K-ras mutations in the pancreatic epithelium. Although both smoking and K-ras mutations have important roles in the etiopathogenesis of EPC, the 2 processes may act independently.

    Pancreas 2007;35;2;135-41

  • Evaluation of clinical relevance of examining K-ras, p16 and p53 mutations along with allelic losses at 9p and 18q in EUS-guided fine needle aspiration samples of patients with chronic pancreatitis and pancreatic cancer.

    Salek C, Benesova L, Zavoral M, Nosek V, Kasperova L, Ryska M, Strnad R, Traboulsi E and Minarik M

    Laboratory for Molecular Genetics and Oncology, Genomac International Ltd., Bavorska 856, 15541 Prague 5, Czech Republic.

    Aim: To establish an optimum combination of molecular markers resulting in best overall diagnostic sensitivity and specificity for evaluation of suspicious pancreatic mass.

    Methods: Endoscopic ultrasound (EUS)-guided fine needle aspiration cytology (FNA) was performed on 101 consecutive patients (63 males, 38 females, 60 +/- 12 years; 81 with subsequently diagnosed pancreatic cancer, 20 with chronic pancreatitis) with focal pancreatic mass. Samples were evaluated on-site by an experienced cytopathologist. DNA was extracted from Giemsa stained cells selected by laser microdissection and the presence of K-ras, p53 and p16 somatic mutations was tested by cycling-gradient capillary electrophoresis (CGCE) and single-strand conformation polymorphism (SSCP) techniques. In addition, allelic losses of tumor suppressor genes p16 (INK4, CDKN2A) and DPC4 (MADH4, SMAD4) were detected by monitoring the loss of heterozygosity (LOH) at 9p and 18q, respectively.

    Results: Sensitivity and specificity of EUS-guided FNA were 75% and 85%, positive and negative predictive value reached 100%. The remaining 26% samples were assigned as inconclusive. Testing of molecular markers revealed sensitivity and specificity of 70% and 100% for K-ras mutations (P < 0.001), 24% and 90% for p53 mutations (NS), 13% and 100% for p16 mutations (NS), 85% and 64% for allelic losses at 9p (P < 0.001) and 78% and 57% for allelic losses at 18q (P < 0.05). When tests for different molecular markers were combined, the best results were obtained with K-ras + LOH at 9p (92% and 64%, P < 0.001), K-ras + LOH at 18q (92% and 57%, P < 0.001), and K-ras + LOH 9q + LOH 18q (96% and 43%, P < 0.001). When the molecular markers were used as complements to FNA cytology to evaluate inconclusive samples only, the overall sensitivity of cancer detection was 100% in all patients enrolled in the study.

    Conclusion: EUS-guided FNA cytology combined with screening of K-ras mutations and allelic losses of tumor suppressors p16 and DPC4 represents a very sensitive approach in screening for pancreatic malignancy. Molecular markers may find its use particularly in cases where FNA cytology has been inconclusive.

    World journal of gastroenterology : WJG 2007;13;27;3714-20

  • The development of high-grade serous carcinoma from atypical proliferative (borderline) serous tumors and low-grade micropapillary serous carcinoma: a morphologic and molecular genetic analysis.

    Dehari R, Kurman RJ, Logani S and Shih IeM

    Department of Pathology, Gynecology and Obstetrics, Johns Hopkins Medical Institutions, Baltimore, MD, USA.

    Recently, we have proposed a model for the development of ovarian surface epithelial tumors. In this model, all histologic types of surface epithelial tumors are divided into 2 categories designated type I and type II which correspond to 2 pathways of tumorigenesis. Type I tumors include low-grade serous carcinoma, mucinous carcinoma, endometrioid carcinoma, malignant Brenner tumor, and clear cell carcinoma which develop slowly in a stepwise fashion from well-recognized precursors, namely atypical proliferative (borderline) tumors. Type II tumors are high-grade, rapidly growing tumors that typically have spread beyond the ovaries at presentation. They include high-grade serous carcinoma ("moderately" and "poorly" differentiated), malignant mixed mesodermal tumors (carcinosarcomas), and undifferentiated carcinoma. These tumors are rarely associated with morphologically recognizable precursor lesions and it has been proposed that they develop "de novo" from ovarian inclusion cysts. This model implies that the pathogenesis of type I and type II tumors are separate and independent but it is not clear whether some type II tumors develop from type I tumors. In this study, we attempted to address this issue by determining the clonality of 6 cases of high-grade serous carcinomas that were closely associated with atypical proliferative serous (borderline) tumors and invasive low-grade micropapillary serous carcinomas. We reviewed 210 ovarian serous tumors from the surgical pathology files of the Johns Hopkins Hospital and identified 3 high-grade serous carcinoma that were directly associated with atypical proliferative serous (borderline) tumors and 3 that were associated with invasive low-grade micropapillary serous carcinomas. A morphologic continuum between the high-grade carcinoma and the low-grade tumors was observed in 4 cases whereas in the remaining 2 cases the high-grade and low-grade components were separate. Mutational analyses for KRAS, BRAF, and p53 genes were performed on microdissected samples from the high-grade and low-grade tumor areas for each case. All 6 tumors demonstrated wild-type BRAF and p53 genes. Only 2 of the 6 cases were informative from a molecular genetic standpoint. In those 2 cases we found the same mutations of KRAS in both the atypical proliferative serous (borderline) tumor and the high-grade serous carcinoma component of the tumor, indicating a clonal relationship. The above results suggest that the majority of high-grade and low-grade carcinomas develop independently but in rare cases, a high-grade serous carcinoma may arise from an atypical proliferative serous (borderline) tumor.

    The American journal of surgical pathology 2007;31;7;1007-12

  • Acquisition of anoikis resistance promotes the emergence of oncogenic K-ras mutations in colorectal cancer cells and stimulates their tumorigenicity in vivo.

    Derouet M, Wu X, May L, Hoon Yoo B, Sasazuki T, Shirasawa S, Rak J and Rosen KV

    Department of Pediatrics, Atlantic Research Center, Dalhousie University, Halifax, Nova Scotia, Canada.

    Detachment from the extracellular matrix causes apoptosis of normal epithelial cells--a phenomenon called anoikis. K-ras oncogene, an established anoikis inhibitor, often occurs in colorectal carcinoma (CRC). In addition to blocking anoikis-inducing mechanisms, oncogenic K-ras can cause anoikis-unrelated changes in CRC cells, such as induction of events promoting their deregulated mitogenesis, ability to trigger angiogenesis, and so on. Thus, whether ras-induced anoikis resistance of CRC cells is essential for their ability to form tumors in vivo or represents a mere epiphenomenon is unclear. We found that when poorly tumorigenic, oncogenic, K-ras-negative, anoikis-susceptible human CRC cells were cultured under anoikis-inducing conditions in vitro, they spontaneously gave rise to an anoikis-resistant cell population harboring de novo oncogenic K-ras mutations and manifesting dramatically increased tumorigenicity. We further observed that a variant of the same oncogenic K-ras-negative anoikis-susceptible cells selected for increased tumorigenicity acquired de novo oncogenic K-ras mutations and manifested increased anoikis resistance. Unlike the case with anoikis, oncogenic K-ras did not rescue CRC cells from death caused by hypoxia or anticancer agents. Taken collectively, our results support the notion that ras-induced anoikis resistance of CRC cells is essential for their ability to form tumors in vivo and thus represents a potential therapeutic target.

    Neoplasia (New York, N.Y.) 2007;9;7;536-45

  • Congenital ulcerating hemangioma in a baby with KRAS mutation and cardio-facio-cutaneous syndrome.

    Tang B, Reardon W, Black GC and Kerr BA

    Academic Unit of Medical Genetics and Regional Genetic Service, Central Manchester and Manchester University Hospital NHS Trust, Manchester, UK. ben6383@hotmail.com

    CFC syndrome is a genetically heterogenous condition. Missense mutations have been identified in BRAF, KRAS, MEK1 and MEK2. We have reported here a KRAS mutation in a baby girl with an early clinical diagnosis of CFC syndrome associated with a large ulcerating hemangioma. Although ectodermal abnormalities have been described in all individuals with this condition, features such as ichthyosis and hemangioma have been previously found only in those patients carrying a mutation in BRAF, and not in KRAS. The findings we have described contrast with these observations. The relatively high frequency of hemangiomas in CFC syndrome suggests that defects in the expression of the MAPK pathway may alter endothelial cell proliferation. Increased understanding of how the molecular pathways with which defects in CFC syndrome predispose affected individuals to hemangiomas might offer insights into the pathogenesis of this common childhood tumour in the general population.

    Clinical dysmorphology 2007;16;3;203-6

  • De novo HRAS and KRAS mutations in two siblings with short stature and neuro-cardio-facio-cutaneous features.

    Søvik O, Schubbert S, Houge G, Steine SJ, Norgård G, Engelsen B, Njølstad PR, Shannon K and Molven A

    Section for Pediatrics, Department of Clinical Medicine, University of Bergen, Bergen, Norway.

    Mutations in genes involved in Ras signalling cause Noonan syndrome and other disorders characterised by growth disturbances and variable neuro-cardio-facio-cutaneous features. We describe two sisters, 46 and 31 years old, who presented with dysmorphic features, hypotonia, feeding difficulties, retarded growth and psychomotor retardation early in life. The patients were initially diagnosed with Costello syndrome, and autosomal recessive inheritance was assumed. Remarkably, however, we identified a germline HRAS mutation (G12A) in one sister and a germline KRAS mutation (F156L) in her sibling. Both mutations had arisen de novo. The F156L mutant K-Ras protein accumulated in the active, guanosine triphosphate-bound conformation and affected downstream signalling. The patient harbouring this mutation was followed for three decades, and her cardiac hypertrophy gradually normalised. However, she developed severe epilepsy with hippocampal sclerosis and atrophy. The occurrence of distinct de novo mutations adds to variable expressivity and gonadal mosaicism as possible explanations of how an autosomal dominant disease may manifest as an apparently recessive condition.

    Funded by: NCI NIH HHS: R01 CA072614, R01 CA104282, R01 CA72614

    Journal of medical genetics 2007;44;7;e84

  • Detection of activated K-ras in non-small cell lung cancer by membrane array: a comparison with direct sequencing.

    Chong IW, Chang MY, Sheu CC, Wang CY, Hwang JJ, Huang MS and Lin SR

    Division of Pulmonary and Critical Care Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan, R.O.C.

    The ability to detect K-ras oncogene may provide additional information for the management of patients with non-small cell lung cancer (NSCLC). In the present study, we detected the K-ras oncogene in 76 patients with NSCLC by two methods: direct sequencing of K-ras in tumor tissues and membrane array detection of the gene overexpression specific for activated K-ras in peripheral blood. The results showed that 28 (36.8%) of the 76 Taiwanese NSCLC patients had K-ras mutations, with a frequency of 36.4% (20/55) in adenocarcinomas and 38.1% (8/21) in squamous cell carcinomas. The K-ras mutations were more frequently found in smokers than in non-smokers (51.4 vs. 24.4%, P=0.015). The incidences of K-ras mutation in the subgroups of non-smokers and squamous cell carcinomas are relatively higher in Taiwan than in other countries. On the other hand, the membrane array method could positively detect circulating activated K-ras in all of the 27 NSCLC patients with K-ras mutations at codons 12, 13 and 61, and in 4 of the 48 patients with wild-type K-ras. Our results suggest that the K-ras oncogene membrane array serves as a sensitive and convenient tool for the detection of K-ras oncogene, and therefore, has a great potential for clinical applications.

    Oncology reports 2007;18;1;17-24

  • Disproportionate representation of KRAS gene mutation in atypical adenomatous hyperplasia, but even distribution of EGFR gene mutation from preinvasive to invasive adenocarcinomas.

    Sakamoto H, Shimizu J, Horio Y, Ueda R, Takahashi T, Mitsudomi T and Yatabe Y

    Department of Pathology and Molecular Diagnostics, Aichi Cancer Center, Nagoya, Japan.

    In the resected lung, additional small lesions are occasionally found incidentally, and include the full spectrum of preinvasive to invasive lesions under the current putative schema of the sequential development of lung cancer. In this study, we examined EGFR and KRAS gene mutations in 119 synchronous pulmonary lesions, including 40 precursor lesions (atypical adenomatous hyperplasia, AAH), 26 carcinomas in situ (non-mucinous bronchioloalveolar carcinoma, BAC), 14 minimally invasive adenocarcinomas, 34 overt invasive adenocarcinomas, and five of other subtypes of cancer. Although the mutually exclusive nature of KRAS and EGFR gene mutations was maintained even in preinvasive lesions, the incidences of the lesions along the putative progression schema were quite different. The KRAS gene was mutated in 33% of AAH, 12% of carcinomas in situ, 8% of minimally invasive adenocarcinomas and 0% of well-differentiated adenocarcinomas, whereas the frequencies of EGFR mutation did not fluctuate greatly, at 25%, 51%, 36%, 86% and 67%, respectively. These results are consistent with the findings of a published gene-targeted mouse model; the mice expressing oncogenic KRAS developed AAH but not invasive adenocarcinoma, whereas a spectrum of preinvasive to invasive adenocarcinomas was observed in the mice expressing mutant EGFR. Taking these factors together, it is suggested that AAH could develop by either KRAS or EGFR gene mutation, but AAH harbouring a KRAS gene mutation might not progress further to an invasive cancer.

    The Journal of pathology 2007;212;3;287-94

  • Distinctive evaluation of nonmucinous and mucinous subtypes of bronchioloalveolar carcinomas in EGFR and K-ras gene-mutation analyses for Japanese lung adenocarcinomas: confirmation of the correlations with histologic subtypes and gene mutations.

    Sakuma Y, Matsukuma S, Yoshihara M, Nakamura Y, Noda K, Nakayama H, Kameda Y, Tsuchiya E and Miyagi Y

    Molecular Pathology and Genetics Division, Kanagawa Cancer Center Research Institute, Kanagawa Cancer Center Hospital, Yokohama, Japan.

    Although adenocarcinomas of the lung are associated with epidermal growth factor receptor (EGFR) gene mutations and sensitivity to EGFR tyrosine kinase inhibitors, it remains unclear whether bronchioloalveolar carcinoma (BAC) components and/or subtypes affect these associations. We aimed to clarify correlations between EGFR gene mutations and BAC components and to establish the histologic features as reliable predictors for the mutations. We examined 141 non-small cell lung cancers (NSCLCs), including 118 adenocarcinomas, for mutations in exons 19 and 21 of the EGFR gene together with mutations in codon 12 of the K-ras gene using loop-hybrid mobility shift assays, a highly sensitive polymerase chain reaction-based method. Adenocarcinomas were subdivided into subtypes with a nonmucinous or mucinous BAC component and those without BAC components. In NSCLCs, EGFR mutations were detected in 75 cases (53.2%) and were significantly associated with adenocarcinoma, female sex, and never smoking. Among adenocarcinomas, nonmucinous and mucinous BAC components were significantly associated with EGFR and K-ras gene mutations, respectively. Because EGFR mutations were detected even in most pure nonmucinous BACs, ie, lung adenocarcinoma in situ, EGFR mutation is considered a critical event in the pathogenesis of nonmucinous BAC tumors.

    American journal of clinical pathology 2007;128;1;100-8

  • Food and nutrient intakes and K-ras mutations in exocrine pancreatic cancer.

    Morales E, Porta M, Vioque J, López T, Mendez MA, Pumarega J, Malats N, Crous-Bou M, Ngo J, Rifà J, Carrato A, Guarner L, Corominas JM, Real FX and PANKRAS II Study Group

    Clinical & Molecular Epidemiology of Cancer Unit, Institut Municipal d'Investigació Mèdica (IMIM), Universitat Autònoma de Barcelona, Carrer del Dr Aiguader 88, E-08003 Barcelona, Spain.

    Background: No studies have investigated the relation between K-ras mutations and dietary factors in exocrine pancreatic cancer (EPC), and fewer than 10 studies have done so in other neoplasms.

    Incident cases of EPC were prospectively identified, and interviewed face-to-face during hospital admission. Food and nutrient intakes were measured with a food frequency questionnaire. Logistic regression was used to compare EPC cases (n = 107) with and without K-ras mutations (case-case study).

    Results: K-ras mutations were more common among daily consumers of milk and other dairy products than among non-daily consumers: the odds ratio adjusted by total energy, age, sex, smoking, alcohol and coffee consumption (ORa) was 5.1 (95% CI 1.1 to 24.5, p = 0.040). For all dairy products, including butter, the ORa for the medium and upper tertiles of intake were 5.4 and 11.6, respectively (p for trend = 0.023). The ORa for regular coffee drinkers further adjusted by dairy consumption was 4.7 (95% CI 1.1 to 20.7, p = 0.043). K-ras mutated cases reported a lower intake of vitamin E (ORa = 0.2, p for trend = 0.036), polyunsaturated fats and omega 3 fatty acids (ORa = 0.2; p for trend <0.03).

    Conclusions: Results support the hypothesis that in EPC exposure to specific dietary components or contaminants may influence the occurrence or persistence of K-ras mutations.

    Journal of epidemiology and community health 2007;61;7;641-9

  • Gene expression profiling of epidermal growth factor receptor/KRAS pathway activation in lung adenocarcinoma.

    Shibata T, Hanada S, Kokubu A, Matsuno Y, Asamura H, Ohta T, Sakamoto M and Hirohashi S

    Cancer Genomics Project, Pathology Division, National Cancer Center Research Institute, Tokyo, Japan. tashibat@ncc.go.jp

    We examined the genome-wide expression profiles of 86 primary lung adenocarcinomas and compared them with the mutation status of the four key molecules (EGFR, ERBB2, KRAS and BRAF) in the EGFR/KRAS/BRAF pathway. Unsupervised classification revealed two subtypes (the bronchial type and the alveolar type) of lung adenocarcinoma. Mutually exclusive somatic mutations of the epidermal growth factor receptor (EGFR) gene (36/86, 41.8%), K-ras gene (11/86, 12.8%) and BRAF gene (1/86, 1.1%) were detected. KRAS mutations were observed significantly frequently in bronchial-type tumors, whereas the frequencies of EGFR mutations were similar in both the alveolar and bronchial types. Twenty-seven genes showed increased expression in EGFR-mutated tumors and these included molecules that function in the EGFR/KRAS/BRAF pathway (EGFR, AKT1 and BCR). In particular, expression of BCR, which is required for EGFR protein degradation, was induced by EGF stimulation, suggesting a negative feedback loop in lung cancer. A subgroup of the alveolar type tumors showed significantly better prognosis than other tumors. Integrated analysis of genetic and gene expression profiling aimed to delineate inherent oncogenic pathways in cancer will be valuable not only for the understanding of molecular pathogenesis, but also for discovering novel biomarkers and predicting clinical outcome.

    Cancer science 2007;98;7;985-91

  • Mucinous differentiation correlates with absence of EGFR mutation and presence of KRAS mutation in lung adenocarcinomas with bronchioloalveolar features.

    Finberg KE, Sequist LV, Joshi VA, Muzikansky A, Miller JM, Han M, Beheshti J, Chirieac LR, Mark EJ and Iafrate AJ

    Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA.

    Somatic mutations in the epidermal growth factor receptor gene (EGFR) are detected in a subset of lung adenocarcinomas, particularly bronchioloalveolar carcinoma (BAC) and adenocarcinoma with bronchioloalveolar features (AWBF), and correlate with clinical response to tyrosine kinase inhibitors (TKIs). In contrast, lung adenocarcinomas refractory to TKIs often have activating mutations in KRAS but lack EGFR mutations. Some adenocarcinomas have mucinous histology, but the clinical and molecular significance of the mucinous pattern is less well studied. We analyzed 43 BAC and AWBF tumors submitted for EGFR mutation testing to identify histopathological features that predicted EGFR or KRAS mutations. EGFR mutations were detected in 14 of 30 (47%) nonmucinous tumors, whereas 0 of 13 mucinous tumors harbored an EGFR mutation (P = 0.003). Missense mutations in KRAS codon 12 were detected in six of seven (86%) mucinous adenocarcinomas but only 3 of 18 (17%) nonmucinous adenocarcinomas (P = 0.003). Thus, in BAC/AWBF mucinous differentiation was significantly correlated with the absence of EGFR mutation and presence of KRAS mutation, suggesting that mucinous BACs/AWBFs are unlikely to respond to TKIs. Therefore, our data suggest that EGFR sequence analysis could be avoided in BAC/AWBF when true mucinous morphology is identified, avoiding the associated testing costs.

    The Journal of molecular diagnostics : JMD 2007;9;3;320-6

  • No duplicate KRAS mutation is identified on the same allele in gastric or colorectal cancer cells with multiple KRAS mutations.

    Kimura K, Nagasaka T, Hoshizima N, Sasamoto H, Notohara K, Takeda M, Kominami K, Iishii T, Tanaka N and Matsubara N

    Department of Gastroenterological Surgery and Surgical Oncology, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan.

    Codon 12 and 13 mutations in 170 colorectal cancer (CRC) and 66 gastric cancer (GC) specimens were analysed by an 'enriched' polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. All identified mutations were verified by direct sequencing of the second PCR products. Among the 170 CRC specimens, mutations were identified in 47 (28%) and 13 (7.6%) cases in codons 12 and 13, respectively. In the 66 GC specimens examined, however, mutations in codons 12 and 13 were only detected in two (3.0%) and one (1.5%) cases, respectively. Mutations in both codon 12 and 13 were found in 3/170 (1.8%) CRCs and 1/66 (1.5%) GCs. Duplicate mutations were never identified in the same allele, which was confirmed by direct sequencing of the second amplified products. The majority of colorectal and gastric cancer cells with KRAS mutations are homogeneous because they have the same KRAS mutation. A few colorectal or gastric cancers, however, showed heterogeneity, as verified by the fact that single mutations were identified in the same allele.

    The Journal of international medical research 2007;35;4;450-7

  • Patterns of EGFR, HER2, TP53, and KRAS mutations of p14arf expression in non-small cell lung cancers in relation to smoking history.

    Mounawar M, Mukeria A, Le Calvez F, Hung RJ, Renard H, Cortot A, Bollart C, Zaridze D, Brennan P, Boffetta P, Brambilla E and Hainaut P

    IARC, Lyon, France.

    Mutations in the tyrosine kinase domain of the epidermal growth factor receptor EGFR are common in non-small cell lung cancer (NSCLC) of never smokers, whereas HER2 mutations are rare. We have analyzed EGFR and HER2 mutations and the expression of the two products of the CDKN2A gene (p14(arf) and p16(INK4a)) in 116 NSCLC that have been previously analyzed for TP53 and KRAS mutations in relation to smoking history of patients. EGFR mutations were detected in 20 of 116 (17%) tumors, whereas five (4.3%) tumors contained HER2 mutations. No tumor contained both mutations. Of tumors with EGFR or HER2 mutation, 72% were adenocarcinomas, 68% were from never smokers, and 32% were from former smokers. EGFR but not HER2 mutations were mutually exclusive with KRAS mutation. Among never smokers, 11 of 16 tumors with EGFR mutation also had TP53 mutation, in contrast with two of 17 tumors without EGFR mutation (P = 0.0008). Expression of p14(arf), but not p16(ink4a), was more frequently down-regulated in never smokers (62.5%) than ever smokers (35%; P = 0.008). All tumors with EGFR or HER2 mutations and wild-type TP53 showed down-regulation of p14(arf) expression. These observations suggest that functional inactivation of the p14(arf)/p53 connection is required in tumors with EGFR or HER2 mutations, consistent with the notion that these proteins are part of a fail-safe mechanism protecting cells against untimely or excessive mitotic signals.

    Cancer research 2007;67;12;5667-72

  • Spontaneous improvement of hematologic abnormalities in patients having juvenile myelomonocytic leukemia with specific RAS mutations.

    Matsuda K, Shimada A, Yoshida N, Ogawa A, Watanabe A, Yajima S, Iizuka S, Koike K, Yanai F, Kawasaki K, Yanagimachi M, Kikuchi A, Ohtsuka Y, Hidaka E, Yamauchi K, Tanaka M, Yanagisawa R, Nakazawa Y, Shiohara M, Manabe A, Kojima S and Koike K

    Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan.

    Of 11 children with juvenile myelomonocytic leukemia (JMML) carrying RAS mutations (8 with NRAS mutations, 3 with KRAS2 mutations), 5 had a profound elevation in either or both the white blood cells and spleen size at diagnosis. Three patients had no or modest hepatosplenomegaly and mild leukocytosis at presentation but subsequently showed a marked increase in spleen size with or without hematologic exacerbation, for which nonintensive chemotherapy was initiated. The other three patients with NRAS or KRAS2 glycine to serine substitution received no chemotherapy, but hematologic improvement has been observed during a 2- to 4-year follow up. In the third group, all hematopoietic cell lineages analyzed had the RAS mutations at the time of hematologic improvement, whereas DNA obtained from the nails had the wild type. Additionally, numbers of circulating granulocyte-macrophage progenitors were significantly reduced during the clinical course. Thus, some patients with JMML with specific RAS mutations may have spontaneously improving disease.

    Blood 2007;109;12;5477-80

  • A subset of colorectal carcinomas express c-KIT protein independently of BRAF and/or KRAS activation.

    Preto A, Moutinho C, Velho S, Oliveira C, Rebocho AP, Figueiredo J, Soares P, Lopes JM and Seruca R

    Institute of Molecular Pathology and Immunology of the University of Porto, Rua Dr Roberto Frias s/n, 4200-465 Porto, Portugal. apreto@ipatimup.pt

    c-KIT is a tyrosine kinase receptor found to be overexpressed in several tumours, namely, GISTs, breast, lung, prostate, ovarian and colorectal carcinomas (CRC). We aimed at determining the frequency of c-KIT expression and mutations in a series of 109 CRC cases (73 primary tumours and 36 lymph node metastases) characterised for KRAS and BRAF mutations. We also aimed at analysing the cellular effects of STI571/Gleevec in CRC-derived cell lines displaying c-KIT expression and KRAS or BRAF mutations. By immunohistochemistry, we found c-KIT overexpression in 15% (11/73) of primary tumours and in 14% (5/36) of metastasis; however, cases showing overexpression did not show c-kit mutations in hotspot regions. The majority (64%) of primary tumours with c-KIT overexpression had mutations at KRAS-BRAF genes. The same was true for 60% of the metastases. We treated CRC cell lines with STI571/Gleevec and verified that it inhibits proliferation and induces apoptosis in all cell lines. In conclusion, overexpression of c-KIT is observed in a subset of primary and CRC metastases in the absence of c-kit mutations. STI571/Gleevec increases apoptosis in CRC cell lines independently of its genetic profile, suggesting that STI571/Gleevec is likely to be an alternative drug for the clinical trials of CRC.

    Virchows Archiv : an international journal of pathology 2007;450;6;619-26

  • Clinical features reflect exon sites of EGFR mutations in patients with resected non-small-cell lung cancer.

    Na II, Rho JK, Choi YJ, Kim CH, Koh JS, Ryoo BY, Yang SH and Lee JC

    Department of Internal Medicine, Korea Cancer Center Hospital, Korea Institute of Radiological & Medical Sciences, 215-4 Gongneung-dong, Nowon-gu, Seoul, Korea.

    The aim of the current study was to determine the clinical significance according to the subtypes of epidermal growth factor receptor (EGFR) mutations and presence of KRAS mutations in operable non-small-cell lung cancer (NSCLC). We sequenced exons 18-21 of the EGFR tyrosine kinase domain and examined mutations in codons 12 and 13 of KRAS in tissues of patients with NSCLC who had undergone surgical resection. EGFR mutations were more frequent in never-smokers than smokers (33% vs. 14%, respectively; p=0.009) and in females than in males (31% vs. 16%, respectively; p=0.036). Mutations in exon 18-19 and 20-21 were found in 10 and 22 patients, respectively. Never-smokers and broncho-alveolar cell carcinoma features were positively associated with a mutation in exon 18-19 (p=0.027 and 0.016, respectively). The five-year survival rate in patients with a mutation in exons 18-19 (100%) was higher than that in patients without such mutation (47%; p=0.021). KRAS mutations were found in 16 patients (12%) and were not related to the overall survival (p=0.742). Patients with an EGFR mutation in exons 18-19 had better survival than patients without such mutation. Subtypes of EGFR mutations may be prognostic factors in patients undergoing curative resection.

    Journal of Korean medical science 2007;22;3;393-9

  • Inverse correlation between RASSF1A hypermethylation, KRAS and BRAF mutations in cervical adenocarcinoma.

    Kang S, Kim HS, Seo SS, Park SY, Sidransky D and Dong SM

    Research Institute and Hospital, National Cancer Center, Goyang, Gyeonggi, 411-769, Republic of Korea.

    Objective: Although the incidence of cervical adenocarcinoma is increasing, few genetic and epigenetic changes in its progression have been described. We hypothesized that RASSF1A methylation and KRAS and BRAF mutations may play an important role in cervical adenocarcinoma.

    Methods: Archival primary carcinoma tissues (n=258) in uterine cervix consisting cervical adenocarcinomas (n=115) and squamous cell carcinomas (n=143) were evaluated for activating mutations of BRAF and KRAS and promoter hypermethylation of RASSF1A using methylation specific PCR and specific sequence analysis. HPV E7 Type-specific PCR was used for HPV-16 and -18 status.

    Results: KRAS mutations were found in 16 adenocarcinomas (13.9%), while BRAF mutations were found in 5 (4.3%). RASSF1A methylation was found in 27 adenocarcinomas (23.5%) and inversely correlated with KRAS and/or BRAF mutation (p=0.002) in cervical adenocarcinoma. In cervical squamous cell carcinomas, KRAS mutations were detected only in 1 (0.7%) cases and RASSF1A hypermethylation was detected in 2 (1.4%). The frequency of KRAS mutation and RASSF1A methylation were significantly different between adenocarcinomas (P<0.001) and squamous cell carcinomas (P<0.001). Neither KRAS mutation nor RASSF1A methylation were associated with HPV status. RASSF1A hypermethylation and KRAS mutations and BRAF mutations are inversely correlated and play an important role in the development of adenocarcinomas.

    Conclusions: These results are suggesting that these two histological types of cervical cancer arise through different molecular pathways in tumor development. Different genetic/epigenetic alterations may explain the possible different therapeutic responsiveness between adenocarcinoma and squamous cell carcinoma of uterine cervix seen in clinic.

    Gynecologic oncology 2007;105;3;662-6

  • KRAS mutation is an important predictor of resistance to therapy with epidermal growth factor receptor tyrosine kinase inhibitors in non-small-cell lung cancer.

    Massarelli E, Varella-Garcia M, Tang X, Xavier AC, Ozburn NC, Liu DD, Bekele BN, Herbst RS and Wistuba II

    Department of Thoracic/Head and Neck Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030-4009, USA.

    Purpose: EGFR gene mutations and increased EGFR copy number have been associated with favorable response to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKI) in patients with non-small-cell lung cancer (NSCLC). In contrast, KRAS mutation has been shown to predict poor response to such therapy. We tested the utility of combinations of these three markers in predicting response and survival in patients with NSCLC treated with EGFR-TKIs.

    Patients with advanced NSCLC treated with EGFR-TKI with available archival tissue specimens were included. EGFR and KRAS mutations were analyzed using PCR-based sequencing. EGFR copy number was analyzed using fluorescence in situ hybridization.

    Results: The study included 73 patients, 59 of whom had all three potential markers successfully analyzed. EGFR mutation was detected in 7 of 71 patients (9.8%), increased EGFR copy number in 32 of 59 (54.2%), and KRAS mutation in 16 of 70 (22.8%). EGFR mutation (P<0.0001) but not increased EGFR copy number (P=0.48) correlated with favorable response. No survival benefit was detected in patients with either of these features. KRAS mutation correlated with progressive disease (P=0.04) and shorter median time to progression (P=0.0025) but not with survival. Patients with both EGFR mutation and increased EGFR copy number had a >99.7% chance of objective response, whereas patients with KRAS mutation with or without increased EGFR copy number had a >96.5% chance of disease progression.

    Conclusion: KRAS mutation should be included as indicator of resistance in the panel of markers used to predict response to EGFR-TKIs in NSCLC.

    Funded by: NCI NIH HHS: CA16672

    Clinical cancer research : an official journal of the American Association for Cancer Research 2007;13;10;2890-6

  • Oncogenic K-RAS subverts the antiapoptotic role of N-RAS and alters modulation of the N-RAS:gelsolin complex.

    Keller JW, Haigis KM, Franklin JL, Whitehead RH, Jacks T and Coffey RJ

    Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.

    Activating mutations in members of the RAS family of genes are among the most common genetic events in human tumorigenesis. Once thought to be functionally interchangeable, it is increasingly recognized that the classical members of this protein family (H-RAS, N-RAS and K-RAS4B) exhibit unique and shared functions that are highly context-dependent. Herein, we demonstrate that the presence of an oncogenic KRAS allele results in elevated levels of GTP-bound N-RAS (N-RAS.GTP) in two human colorectal cancer cell lines, HCT 116 and DLD-1, compared to their isogenic counterparts in which the mutant KRAS allele has been disrupted by homologous recombination. N-RAS subserves an antiapoptotic role in cells expressing wild-type K-RAS; this function is compromised, however, by the presence of mutant K-RAS, and these cells display increased sensitivity to apoptotic stimuli. We additionally identify a physical interaction between N-RAS and gelsolin, a factor that has been shown to promote survival and show that the N-RAS:gelsolin complex is modulated differently in wild-type and mutant K-RAS environments following apoptotic challenge. These findings represent the first biochemical evidence of a functional relationship between endogenous RAS proteins and identify a dynamic physical interaction between endogenous N-RAS and gelsolin that correlates with survival.

    Funded by: NCI NIH HHS: P50 CA095103, P50 CA095103-06, R01 CA046413, R01 CA046413-19, R01 CA46413, U01 CA084239, U01 CA084239-09; PHS HHS: P50 95103, U01 084239

    Oncogene 2007;26;21;3051-9

  • Mutational analysis of EGFR and related signaling pathway genes in lung adenocarcinomas identifies a novel somatic kinase domain mutation in FGFR4.

    Marks JL, McLellan MD, Zakowski MF, Lash AE, Kasai Y, Broderick S, Sarkaria IS, Pham D, Singh B, Miner TL, Fewell GA, Fulton LL, Mardis ER, Wilson RK, Kris MG, Rusch VW, Varmus H and Pao W

    Human Oncology and Pathogenesis Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America.

    Background: Fifty percent of lung adenocarcinomas harbor somatic mutations in six genes that encode proteins in the EGFR signaling pathway, i.e., EGFR, HER2/ERBB2, HER4/ERBB4, PIK3CA, BRAF, and KRAS. We performed mutational profiling of a large cohort of lung adenocarcinomas to uncover other potential somatic mutations in genes of this signaling pathway that could contribute to lung tumorigenesis.

    We analyzed genomic DNA from a total of 261 resected, clinically annotated non-small cell lung cancer (NSCLC) specimens. The coding sequences of 39 genes were screened for somatic mutations via high-throughput dideoxynucleotide sequencing of PCR-amplified gene products. Mutations were considered to be somatic only if they were found in an independent tumor-derived PCR product but not in matched normal tissue. Sequencing of 9MB of tumor sequence identified 239 putative genetic variants. We further examined 22 variants found in RAS family genes and 135 variants localized to exons encoding the kinase domain of respective proteins. We identified a total of 37 non-synonymous somatic mutations; 36 were found collectively in EGFR, KRAS, BRAF, and PIK3CA. One somatic mutation was a previously unreported mutation in the kinase domain (exon 16) of FGFR4 (Glu681Lys), identified in 1 of 158 tumors. The FGFR4 mutation is analogous to a reported tumor-specific somatic mutation in ERBB2 and is located in the same exon as a previously reported kinase domain mutation in FGFR4 (Pro712Thr) in a lung adenocarcinoma cell line.

    This study is one of the first comprehensive mutational analyses of major genes in a specific signaling pathway in a sizeable cohort of lung adenocarcinomas. Our results suggest the majority of gain-of-function mutations within kinase genes in the EGFR signaling pathway have already been identified. Our findings also implicate FGFR4 in the pathogenesis of a subset of lung adenocarcinomas.

    Funded by: NCI NIH HHS: K08 CA097980, K08-CA097980

    PloS one 2007;2;5;e426

  • Activated Ras induces cytoplasmic vacuolation and non-apoptotic death in glioblastoma cells via novel effector pathways.

    Kaul A, Overmeyer JH and Maltese WA

    Department of Biochemistry and Cancer Biology, University of Toledo College of Medicine, Toledo, Ohio 43614, USA.

    Expression of activated H-Ras induces a unique form of non-apoptotic cell death in human glioblastoma cells and other specific tumor cell lines. The major cytopathological features of this form of death are the accumulation of large phase-lucent, LAMP1-positive, cytoplasmic vacuoles. In this study we sought to determine if induction of cytoplasmic vacuolation a) depends on Ras farnesylation, b) is specific to H-Ras, and c) is mediated by signaling through the major known Ras effector pathways. We find that the unusual effects of activated H-Ras depend on farnesylation and membrane association of the GTPase. Both H-Ras(G12V) and K-Ras4B(G12V) stimulate vacuolation, but activated forms of Cdc42 and RhoA do not. Amino acid substitutions in the Ras effector domain, which are known to selectively impair its interactions with Raf kinase, class-I phosphatidylinositide 3-kinase (PI3K), or Ral nucleotide exchange factors, initially pointed to Raf as a possible mediator of cell vacuolation. However, the MEK inhibitor, PD98059, did not block the induction of vacuoles, and constitutively active Raf-Caax did not mimic the effects of Ras(G12V). Introduction of normal PTEN together with H-Ras(G12V) into U251 glioblastoma cells reduced the PI3K-dependent activation of Akt, but had no effect on vacuolation. Finally, co-expression of H-Ras(G12V) with a dominant-negative form of RalA did not suppress vacuolation. Taken together, the observations indicate that Ras activates non-conventional and perhaps unique effector pathways to induce cytoplasmic vacuolation in glioblastoma cells. Identification of the relevant signaling pathways may uncover specific molecular targets that can be manipulated to activate non-apoptotic cell death in this type of cancer.

    Funded by: NCI NIH HHS: R01 CA034569, R01 CA115495, R01 CA34569

    Cellular signalling 2007;19;5;1034-43

  • Impact of epidermal growth factor receptor (EGFR) kinase mutations, EGFR gene amplifications, and KRAS mutations on survival of pancreatic adenocarcinoma.

    Lee J, Jang KT, Ki CS, Lim T, Park YS, Lim HY, Choi DW, Kang WK, Park K and Park JO

    Division of Hematology-Oncology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.

    Background: Erlotinib, in combination with gemcitabine, has shown clinical benefits in pancreatic adenocarcinoma patients. The presence of EGFR mutations and increased EGFR copy numbers in pancreatic adenocarcinoma was explored.

    Methods: Sixty-six pancreatic cancer patients were included in the analysis. The EGFR mutation was analyzed by DNA sequencing of exons 18-21 in the tyrosine kinase domain. KRAS mutation was analyzed by sequencing codons 12, 13, and 61. Quantitative real-time polymerase chain reaction was performed to analyze the copy number of EGFR.

    Results: In the current study the EGFR mutation was harbored in only 1 (1.5%) of the 66 inoperable or metastatic pancreatic adenocarcinoma patients. Amino acid substitution was detected in exon 20 of the EGFR gene. Increased EGFR copy numbers (> or =3.0 per cell) were detected in 26 (41%) patients. There was only 1 patient, who had a highly increased EGFR copy number (> or =6.0 per cell), who died, 2.1 months from the date of diagnosis. The EGFR amplification did not significantly influence survival in pancreatic adenocarcinoma patients (P = .935). Thirty-two (49%) of the 65 pancreatic adenocarcinomas examined harbored a point mutation in codons 12 (n = 31) and 61 (n = 1) of the KRAS gene. The presence of a point mutation in codon 12 adversely influenced survival of pancreatic cancer patients (P = .030).

    Conclusions: The incidence of somatic mutations in the tyrosine kinase domains of EGFR was very low and the increased gene copy number of EGFR did not significantly influence survival.

    Cancer 2007;109;8;1561-9

  • Molecular and clinical characterization of cardio-facio-cutaneous (CFC) syndrome: overlapping clinical manifestations with Costello syndrome.

    Narumi Y, Aoki Y, Niihori T, Neri G, Cavé H, Verloes A, Nava C, Kavamura MI, Okamoto N, Kurosawa K, Hennekam RC, Wilson LC, Gillessen-Kaesbach G, Wieczorek D, Lapunzina P, Ohashi H, Makita Y, Kondo I, Tsuchiya S, Ito E, Sameshima K, Kato K, Kure S and Matsubara Y

    Department of Medical Genetics, Tohoku University School of Medicine, Sendai, Japan.

    Cardio-facio-cutaneous (CFC) syndrome is a multiple congenital anomaly/mental retardation syndrome characterized by heart defects, a distinctive facial appearance, ectodermal abnormalities and mental retardation. Clinically, it overlaps with both Noonan syndrome and Costello syndrome, which are caused by mutations in two genes, PTPN11 and HRAS, respectively. Recently, we identified mutations in KRAS and BRAF in 19 of 43 individuals with CFC syndrome, suggesting that dysregulation of the RAS/RAF/MEK/ERK pathway is a molecular basis for CFC syndrome. The purpose of this study was to perform comprehensive mutation analysis in 56 patients with CFC syndrome and to investigate genotype-phenotype correlation. We analyzed KRAS, BRAF, and MAP2K1/2 (MEK1/2) in 13 new CFC patients and identified five BRAF and one MAP2K1 mutations in nine patients. We detected one MAP2K1 mutation in three patients and four new MAP2K2 mutations in four patients out of 24 patients without KRAS or BRAF mutations in the previous study [Niihori et al., 2006]. No mutations were identified in MAPK3/1 (ERK1/2) in 21 patients without any mutations. In total, 35 of 56 (62.5%) patients with CFC syndrome had mutations (3 in KRAS, 24 in BRAF, and 8 in MAP2K1/2). No significant differences in clinical manifestations were found among 3 KRAS-positive patients, 16 BRAF-positive patients, and 6 MAP2K1/2-positive patients. Wrinkled palms and soles, hyperpigmentation and joint hyperextension, which have been commonly reported in Costello syndrome but not in CFC syndrome, were observed in 30-40% of the mutation-positive CFC patients, suggesting a significant clinical overlap between these two syndromes.

    American journal of medical genetics. Part A 2007;143A;8;799-807

  • Mutations in BRAF and KRAS differentially distinguish serrated versus non-serrated hyperplastic aberrant crypt foci in humans.

    Rosenberg DW, Yang S, Pleau DC, Greenspan EJ, Stevens RG, Rajan TV, Heinen CD, Levine J, Zhou Y and O'Brien MJ

    Colon Cancer Prevention Program, NEAG Comprehensive Cancer Center, and Center for Molecular Medicine, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA. Rosenberg@nso2.uchc.edu

    We previously reported that colon carcinomas, adenomas, and hyperplastic polyps exhibiting a serrated histology were very likely to possess BRAF mutations, whereas when these same advanced colonic lesions exhibited non-serrated histology, they were wild type for BRAF; among hyperplastic polyps, KRAS mutations were found mainly in a non-serrated variant. On this basis, we predicted that hyperplastic aberrant crypt foci (ACF), a putative precancerous lesion found in the colon, exhibiting a serrated phenotype would also harbor BRAF mutations and that non-serrated ACF would not. In contrast, KRAS mutations would be found more often in the non-serrated ACF. We examined 55 ACF collected during screening colonoscopy from a total of 28 patients. Following laser capture microdissection, DNA was isolated, and mutations in BRAF and KRAS were determined by direct PCR sequencing. When hyperplastic lesions were further classified into serrated and non-serrated histologies, there was a strong inverse relationship between BRAF and KRAS mutations: a BRAF(V600E) mutation was identified in 10 of 16 serrated compared with 1 of 33 non-serrated lesions (P = 0.001); conversely, KRAS mutations were present in 3 of 16 serrated compared with 14 of 33 non-serrated lesions. Our finding of a strong association between BRAF mutations and serrated histology in hyperplastic ACF supports the idea that these lesions are an early, sentinel, or a potentially initiating step on the serrated pathway to colorectal carcinoma.

    Funded by: NCI NIH HHS: CA 81428

    Cancer research 2007;67;8;3551-4

  • Histopathological and genetic differences between polypoid and non-polypoid submucosal colorectal carcinoma.

    Hirata I, Wang FY, Murano M, Inoue T, Toshina K, Nishikawa T and Maemura K

    Department of Gastroenterology, Fujita Health University, 1-98 Dengakugakubo Katsukage-Cho, Toyoake, Aichi 470-1192, Japan. ihirata@fujita-hu.ac.jp

    Aim: To investigate the histopathological and genetic differences between polypoid growth (PG) and non-polypoid growth (NPG) submucosal invasive colorectal carcinoma (CRC).

    Methods: A total of 96 cases of submucosal CRC were divided into two groups according to their growth type; 60 cases of PG and 36 cases of NPG. The size, histological degree of dysplasia, depth of submucosal invasion and lymph node metastasis were compared between the two groups. Furthermore, expression of p53 was detected by immunohistochemical staining, and K-ras gene mutation was examined by polymerase chain reaction based single-strand conformation polymorphism (SSCP).

    Results: The average size of the lesions in the NPG group was significantly smaller than those in the PG group (7.5 mm vs 13.8 mm, P<0.001). The histological degree of dysplasia tended to be more severe in NPG group, while the incidence of submucosal massive invasion and the lymph node metastasis were both significantly higher in the NPG type than in the PG group (64.3% vs 43.3%, P=0.004; 43% vs 7%, P=0.008, respectively). In addition, K-ras gene mutations were detected in 67% of lesions in the PG group, but none in the NPG group, while no difference in p53 immunohistochemical expression was found between the two groups.

    Conclusion: Compared with PG submucosal CRC, NPG type demonstrates more frequent submucosal massive invasion, more lymph node metastasis and a higher degree dysplasia. Genetically, NPG type shows much less frequent K-ras mutation.

    World journal of gastroenterology : WJG 2007;13;14;2048-52

  • Further evidence for a somatic KRAS mutation in a pilocytic astrocytoma.

    Janzarik WG, Kratz CP, Loges NT, Olbrich H, Klein C, Schäfer T, Scheurlen W, Roggendorf W, Weiller C, Niemeyer C, Korinthenberg R, Pfister S and Omran H

    Department of Neurology, University Hospital Freiburg, Freiburg, Germany.

    Astrocytomas are the most common brain tumors of childhood. However, knowledge of the molecular etiology of astrocytomas WHO grade I and II is limited. Germline mutations in the Ras-guanosine triphosphatase-activating protein, neurofibromin, in individuals with neurofibromatosis type I predispose to pilocytic astrocytomas. This association suggests that constitutive activation of the Ras signaling pathway plays a fundamental role in astrocytoma development. We screened 25 WHO I and II astrocytomas for mutations of PTPN11, NRAS, KRAS, and HRAS genes and identified the somatic G12A KRAS mutation in one pilocytic astrocytoma. These data suggest that Ras is rarely mutated in these tumors. Analyzed astrocytomas without mutations in Ras or neurofibromin may harbor mutations in other proteins of this pathway leading to hyperactive Ras signaling.

    Neuropediatrics 2007;38;2;61-3

  • K-ras and Dpc4 mutations in chronic pancreatitis: case series.

    Popović Hadzija M, Korolija M, Jakić Razumović J, Pavković P, Hadzija M and Kapitanović S

    Department of Molecular Medicine, Ruder Boskovic Institute, Zagreb, Croatia. mhadzija@irb.hr

    Aim: To assess whether alterations in the K-ras, p53, and DPC4 genes are present in pancreatitis, a potential precancerous condition that can progress to pancreatic adenocarcinoma. To investigate the alterations occurring at hot spots of K-ras (exon 1), p53 (exons 5 and 7), and DPC4 (exons 8, 10 and 11).

    Methods: In 10 patients with acute and 22 with chronic pancreatitis, without pancreatic intraepithelial neoplasia (PanIN), DNA was isolated from paraffin embedded tissue samples. The extracted DNA was analyzed by polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP) analysis, single-strand conformation polymorphism (SSCP) analysis, and DNA sequencing.

    Results: In acute pancreatitis samples no mutations were found in any of the investigated genes. In 7 out of 22 samples of chronic pancreatitis nucleotide substitution at exon 1 of K-ras (five at codon 12 and two at codon 13) were found. No mutations in p53 (exons 5 and 7) were detected. Two samples had nucleotide substitutions at exons 8 and 11 of DPC4, introducing STOP signal and change in the amino acid sequence, respectively. One chronic pancreatitis sample displayed simultaneous mutations in K-ras (exon 1, codon 12) and DPC4 (exon 8, codon 358).

    Conclusion: Mutations of K-ras and Dpc4 genes can accumulate already in non-malignant, inflammatory pancreatic tissue, suggesting its applicability in monitoring of further destruction of pancreatic tissue and progression into malignancy.

    Croatian medical journal 2007;48;2;218-24

  • TGFBR2 mutation is correlated with CpG island methylator phenotype in microsatellite instability-high colorectal cancer.

    Ogino S, Kawasaki T, Ogawa A, Kirkner GJ, Loda M and Fuchs CS

    Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115, USA. shuji_ogino@dfci.harvard.edu

    The transforming growth factor-beta receptor type 2 gene (TGFBR2) is mutated in most microsatellite instability-high (MSI-H) colorectal cancers. Promoter methylation of RUNX3 (runt-related transcription factor 3; encoding a transcription factor downstream of the TGF-beta pathway) is observed in colorectal cancer with CpG island methylator phenotype (CIMP), which is characterized by extensive promoter methylation and is associated with MSI-H and BRAF mutations. However, no study to date has examined interrelationship between TGFBR2 mutation, RUNX3 methylation, and CIMP in colorectal cancer. Using 144 MSI-H colorectal cancers derived from 2 large prospective cohort studies, we analyzed a mononucleotide repeat of TGFBR2 and quantified DNA methylation (by MethyLight technology) in 8 CIMP-specific promoters (RUNX3, CACNA1G [calcium channel, voltage-dependent, T type alpha-1G subunit], CDKN2A [p16], CRABP1 [cellular retinoic acid binding protein 1], IGF2 [insulin-like growth factor 2], MLH1, NEUROG1 [neurogenin 1], and SOCS1 [suppressor of cytokine signaling 1]). Among the 144 MSI-H tumors, the presence of TGFBR2 mutation (overall 72% frequency) was correlated positively with CIMP-high (with >/=6/8 methylated promoters; P < .0001), RUNX3 methylation (P = .0004), BRAF mutation (P = .0006), and right colon (P = .05); inversely with KRAS mutation (P = .006); but not significantly with sex, tumor differentiation, and p53 status (assessed by immunohistochemistry). After stratification by sex, location, tumor differentiation, RUNX3 status, KRAS/BRAF status, or p53 status, CIMP-high was persistently correlated with TGFBR2 mutation. In contrast, RUNX3, KRAS, or BRAF status was no longer correlated with TGFBR2 mutation after stratification by CIMP status. In conclusion, TGFBR2 mutation is associated with CIMP-high and indirectly with RUNX3 methylation. Our findings emphasize the importance of analyzing global epigenomic status (for which CIMP status is a surrogate marker) when correlating a single epigenetic event (eg, RUNX3 methylation) with any other molecular or clinicopathologic variables.

    Funded by: NCI NIH HHS: P01 CA55075-13, P01 CA87969-03

    Human pathology 2007;38;4;614-20

  • The impact of epidermal growth factor receptor gene status on gefitinib-treated Japanese patients with non-small-cell lung cancer.

    Ichihara S, Toyooka S, Fujiwara Y, Hotta K, Shigematsu H, Tokumo M, Soh J, Asano H, Ichimura K, Aoe K, Aoe M, Kiura K, Shimizu K, Date H and Shimizu N

    Department of Cancer and Thoracic Surgery, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama 700-8558, Japan.

    We investigated the relationships between genetic factors and clinical outcome in Japanese non-small-cell lung cancer (NSCLC) patients treated with gefitinib. Ninety-eight NSCLC patients who had been treated with gefitinib, were screened for mutations in epidermal growth factor receptor (EGFR) exons 18-21, KRAS exon2, and polymorphisms including the CA simple sequence repeat in intron1 (CA-SSR1) and single nucleotide polymorphisms in the promoter region (-216G/T and -191C/A), using a PCR-based assay and direct sequencing. The EGFR copy number status was also evaluated using a fluorescence in situ hybridization assay. EGFR and KRAS mutations were found in 38 (38.8%) and 8 (8.2%) of the 98 patients, respectively. A high EGFR copy number status was identified in 31 (41.3%) of the 75 assessable patients. Drug-sensitive EGFR mutations limited to exon19 deletions and L858R were independent predictive factors of a stronger sensitivity to gefitinib (p = 0.0002), the overall survival (OS) (p = 0.0036), and prolonged progression-free survival (PFS) (p < 0.0001). The EGFR copy number status was not related to a sensitivity to gefitinib and prolonged OS and PFS. Regarding polymorphisms, patients with a short CA-SSR1 showed a prolonged OS as compared with those with a long length in patients with a drug-sensitive EGFR mutation, although this difference was not significant (p = 0.13). Thus, drug-sensitive EGFR mutations predict a favorable clinical outcome and a high EGFR copy number may not be related to clinical benefits in gefitinib-treated Japanese patients with NSCLC. Our findings also suggest that the CA-SSR1 length may influence the clinical outcome in patients with a drug-sensitive EGFR mutation.

    International journal of cancer 2007;120;6;1239-47

  • Quantification of oxidative posttranslational modifications of cysteine thiols of p21ras associated with redox modulation of activity using isotope-coded affinity tags and mass spectrometry.

    Sethuraman M, Clavreul N, Huang H, McComb ME, Costello CE and Cohen RA

    Vascular Biology Unit, Boston University School of Medicine, Boston, MA 02118, USA.

    p21ras GTPase is the protein product of the most commonly mutated human oncogene and has been identified as a target for reactive oxygen and nitrogen species. Posttranslational modification of reactive thiols, by reversible S-glutathiolation and S-nitrosation, and potentially also by irreversible oxidation, may have significant effects on p21ras activity. Here we used an isotope-coded affinity tag (ICAT) and mass spectrometry to quantitate the reversible and irreversible oxidative posttranslational thiol modifications of p21ras caused by peroxynitrite (ONOO(-)) or glutathione disulfide (GSSG). The activity of p21ras was significantly increased after exposure to GSSG, but not to ONOO(-). The results of LC-MS/MS analysis of tryptic peptides of p21ras treated with ONOO(-) showed that ICAT labeling of Cys(118) was decreased by 47%, whereas Cys(80) was not significantly affected and was thereby shown to be less reactive. The extent of S-glutathiolation of Cys(118) by GSSG was 53%, and that of the terminal cysteines was 85%, as estimated by the decrease in ICAT labeling. The changes in ICAT labeling caused by GSSG were reversible by chemical reduction, but those caused by peroxynitrite were irreversible. The quantitative changes in thiol modification caused by GSSG associated with increased activity demonstrate the potential importance of redox modulation of p21ras.

    Funded by: NCRR NIH HHS: P41 RR010888, P41RR10888-6; NHLBI NIH HHS: N01-HV-28178, N01HV28178, P01 HL081587, P01 HL081738, T32 HL007224, T32/HL07224; NIA NIH HHS: R01 AG 027080, R01 AG027080

    Free radical biology & medicine 2007;42;6;823-9

  • K-Ras promotes growth transformation and invasion of immortalized human pancreatic cells by Raf and phosphatidylinositol 3-kinase signaling.

    Campbell PM, Groehler AL, Lee KM, Ouellette MM, Khazak V and Der CJ

    Lineberger Comprehensive Cancer Center and Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.

    Mutational activation of the K-Ras oncogene is well established as a key genetic step in the development and growth of pancreatic adenocarcinomas. However, the mechanism by which aberrant Ras signaling promotes uncontrolled pancreatic tumor cell growth remains to be fully elucidated. The recent use of primary human cells to study Ras-mediated oncogenesis provides important model cell systems to dissect this mechanism. We have used a model of telomerase-immortalized human pancreatic duct-derived cells (E6/E7/st) to study mechanisms of Ras growth transformation. First, we found that human papillomavirus E6 and E7 oncogenes, which block the function of the p53 and Rb tumor suppressors, respectively, and SV40 small t antigen were required to allow mutant K-Ras(12D) growth transformation. Second, K-Ras(12D) caused growth transformation in vitro, including enhanced growth rate and loss of density dependency for growth, anchorage independence, and invasion through reconstituted basement membrane proteins, and tumorigenic transformation in vivo. Third, we determined that the Raf, phosphatidylinositol 3-kinase (PI3K), and Ral guanine nucleotide exchange factor effector pathways were activated, although extracellular signal-regulated kinase (ERK) activity was not up-regulated persistently. Finally, pharmacologic inhibition of Raf/mitogen-activated protein kinase/ERK and PI3K signaling impaired K-Ras-induced anchorage-independent growth and invasion. In summary, our studies established, characterized, and validated E6/E7/st cells for the study of Ras-induced oncogenesis.

    Funded by: NCI NIH HHS: CA 106991, CA 42978, P50 CA 106991-02, U01 CA 111294

    Cancer research 2007;67;5;2098-106

  • Distal phalangeal creases--a distinctive dysmorphic feature in disorders of the RAS signalling pathway?

    Ørstavik KH, Tangeraas T, Molven A and Prescott TE

    Department of Medical Genetics, Rikshospitalet-Radiumhospitalet Medical Centre, Oslo, Norway.

    We have observed unusual transverse distal phalangeal creases in two patients, one with Costello syndrome (G12S mutation in the HRAS gene) and one with cardio-facio-cutaneous (CFC) syndrome or possibly Noonan syndrome (Q22E mutation in the KRAS gene). This feature along with fetal pads was present in both children at birth and has persisted until age two years. Distal phalangeal creases, when present, may be a good diagnostic handle for syndromes belonging to the RAS signalling pathway.

    European journal of medical genetics 2007;50;2;155-8

  • EGFR, ERBB2, and KRAS mutations in Korean non-small cell lung cancer patients.

    Bae NC, Chae MH, Lee MH, Kim KM, Lee EB, Kim CH, Park TI, Han SB, Jheon S, Jung TH and Park JY

    Department of Internal Medicine, Kyungpook National University Hospital, Samduk 2Ga 50, Daegu, 700-412, Republic of Korea.

    The epidermal growth factor receptor (EGFR), and its family members play an important role in the development and progression of lung cancers. It has been reported that somatic mutations in the tyrosine kinase domain of the EGFR or ERBB2 genes occur in a subset of patients with lung cancer. We searched for mutations of the EGFR, ERBB2, and KRAS genes in surgically resected non-small cell lung cancers (NSCLCs) to determine the prevalence of these mutations in Korean lung cancer patients. In addition, we examined the relationship between the mutations and clinicopathologic features of lung cancers. Mutations of the EGFR, ERBB2, and KRAS genes were determined by polymerase chain reaction-based direct sequencing in 115 surgically resected non-small cell lung cancers. EGFR mutations were present in 20 patients (17.4%). The EGFR mutations were found only in adenocarcinomas (20 of 55 adenocarcinomas, 36.4%). The ERBB2 mutation was found in 1 adenocarcinoma of the 115 NSCLCs (0.9% overall; 1.8% of the 55 adenocarcinomas). KRAS mutations were found in 6 (5.2%) of the 115 NSCLCs (2 of 60 squamous cell carcinomas, or 3.3%, and 4 of 55 adenocarcinomas, or 7.3%). EGFR mutations in adenocarcinomas were more frequent in women (P = 0.02) and in never-smokers (P = 0.004). EGFR mutations in adenocarcinomas were not associated with pathologic stage in never-smokers, but were more frequent in pathologic stage II-IV than in stage I in ever-smokers (P = 0.01). Of the 55 adenocarcinomas, 25 (45.5%) had mutations of one or another of the three genes; EGFR mutations were never found in adenocarcinomas together with ERBB2 or KRAS mutations. These findings suggest that the EGFR mutation is frequent in Korean lung cancer patients, and that the ERBB2 mutation is rare. Further studies are needed to investigate the role of EGFR mutations in the carcinogenesis of adenocarcinoma among smokers.

    Cancer genetics and cytogenetics 2007;173;2;107-13

  • Oncogenic KRAS provides a uniquely powerful and variable oncogenic contribution among RAS family members in the colonic epithelium.

    Keller JW, Franklin JL, Graves-Deal R, Friedman DB, Whitwell CW and Coffey RJ

    Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.

    Activating mutations of the RAS family of small GTPases are among the most common genetic events in human tumorigenesis. Constitutive activation of the three canonical family members, KRAS, NRAS, and HRAS segregate strongly by tissue type. Of these, KRAS mutations predominate in human tumors, including those arising from the colon and lung. We sought to compare the oncogenic contributions of different RAS isoforms in a comparable genetic setting and to explore downstream molecular changes that may explain the apparent differential oncogenic effects of the various RAS family members. We utilized colorectal cancer cell lines characterized by oncogenic KRAS in parallel with isogenically derived lines in which the mutant allele has been disrupted. We additionally attempted to reconstitute the isogenic derivatives with oncogenic forms of other RAS family members and analyze them in parallel. Pairwise analysis of HCT 116 and DLD-1 cell lines as well as their isogenic derivatives reveals distinct K-RAS(G13D) signatures despite the genetic similarities of these cell lines. In DLD-1, for example, oncogenic K-RAS enhances the motility of these cells by downregulation of Rap1 activity, yet is not associated with increased ERK1/2 phosphorylation. In HCT 116, however, ERK1/2 phosphorylation is elevated relative to the isogenic derivative, but Rap1 activity is unchanged. K-RAS is uniquely oncogenic in the colonic epithelium, though the molecular aspects of its oncogenic contribution are not necessarily conserved across cell lines. We therefore conclude that the oncogenic contribution of K-RAS is a function of its multifaceted functionality and is highly context-dependent.

    Funded by: NCI NIH HHS: CA46413, CA95103, T32 CA009582

    Journal of cellular physiology 2007;210;3;740-9

  • RASSF1A methylation and K-ras and B-raf mutations and recurrent endometrial cancer.

    Pijnenborg JM, Dam-de Veen GC, Kisters N, Delvoux B, van Engeland M, Herman JG and Groothuis PG

    Department of Obstetrics and Gynecology, Tweesteden Hospital, Tilburg, The Netherlands. H.pijnenborg@planet.nl

    Background: Aberrations in mediators of Ras signaling may increase the risk of developing recurrent endometrial carcinoma.

    Primary tumors of patients with (n = 44) and without (n = 44) recurrent stage I endometrioid endometrial carcinoma were compared regarding the presence of K-ras mutations (codons 12 and 13), B-raf mutations (V599), and RASSF1A gene promoter methylation.

    Results: K-ras mutations were present in 18% of the patients independent of recurrent disease. No B-raf mutations were found. RASSF1A methylation was demonstrated in 85% of endometrial carcinomas, independent of recurrence. The presence of K-ras mutations and RASSF1A promoter methylation were not related, either directly or inversely. Analysis in premenopausal endometrial carcinomas demonstrated K-ras mutations in 40%, no B-raf mutations, and RASSF1A promoter methylation in 70% of the cases. RASSF1A methylation was also observed in samples of cyclic (n = 14), hyperplastic (n = 8), and atrophic (n = 13) endometrial tissues in 21%, 50% and 38%, respectively.

    Conclusions: RASSF1A methylation was observed in a high frequency in endometrioid endometrial carcinoma whereas K-ras and B-raf mutations were observed in a low frequency. No association was observed with the development of recurrent disease. High-frequency RASSF1A methylation in premenopausal carcinomas and an increased frequency in endometrial hyperplasia indicate that this may be an early event in endometrial carcinogenesis.

    Annals of oncology : official journal of the European Society for Medical Oncology 2007;18;3;491-7

  • Growth inhibitory effect of wild-type Kras2 gene on a colonic adenocarcinoma cell line.

    Li H, Cao HF, Wan J, Li Y, Zhu ML and Zhao P

    Inpatient Department of Medical Health Center, Chinese PLA General Hospital, Beijing 100853, China.

    Aim: To observe the growth inhibitory effect of wild-type Kras2 gene on a colonic adenocarcinoma cell line Caco-2.

    Methods: Recombinant plasmid pCI-neo-Kras2 with wild type Kras2 open reading frame was constructed. The Caco-2 cells were transfected with either pCI-neo or pCI-neo-Kras2 using Lipofectamine 2000. The expression of wild type Kras2 was examined by Northern blot analysis. And the expression of wild type Kras2 protein was examined by Western blot analysis. The effects of wild-type Kras2 on cell proliferation were analyzed by monotetrazolium (MTT) assay, meanwhile analyses of cell cycle and spontaneous apoptosis rate were carried out by flow cytometry (FCM).

    Results: The plasmid of pCI-neo-Kras2 was successfully established. The growth rate of cells transfected with pCI-neo-Kras2 was significantly lower than the control cells transfected with the empty pCI-neo vector (P<0.05). Cell cycle analysis revealed arrest of the pCI-neo-Kras2 transfected cells in G0/G1 phases, decreased DNA synthesis and decreased fractions of cells in S phase. The proliferative index of cells transfected with pCI-neo-Kras2 was decreased compared with the control cells (49.78% vs 64.21%), while the apoptotic rate of Caco-2 cells with stable Kras2 expression increased (0.30% vs 0.02%).

    Conclusion: The wild-type Kras2 gene effectively inhibits the growth of the colonic adenocarcinoma cell line Caco-2.

    World journal of gastroenterology 2007;13;6;934-8

  • Activation of extracellular regulated kinases (ERK1/2) but not AKT predicts poor prognosis in colorectal carcinoma and is associated with k-ras mutations.

    Schmitz KJ, Wohlschlaeger J, Alakus H, Bohr J, Stauder MA, Worm K, Winde G, Schmid KW and Baba HA

    Institute of Pathology and Neuropathology, University Hospital of Essen, Hufelandstr. 55, 45122 Essen, Germany.

    Signal transduction and modulation represent central mechanisms in cellular processes such as cell-cycle regulation, oncogenesis, and apoptosis. The aim of this study was to determine the prognostic relevance of two kinases important in the regulation of cell proliferation and apoptosis in 135 colorectal cancer cases: AKT and extracellular regulated kinases (ERK1/2). We investigated the relationship of phospho-ERK1/2 (pERK1/2) and phospho-AKT (pAKT) with associated parameters (EGFR, COX-2, cyclin-D1), proliferative activity (Ki-67), and apoptosis (TUNEL) using immunohistochemistry. Additionally, the k-ras gene was screened for mutations to determine its putative association with ERK1/2 activation. Activation of ERK1/2 but not AKT correlated statistically with the presence of k-ras mutations (P = 0.015). Survival analysis of phospho-ERK1/2 immunoexpression showed a significant correlation with decreased overall survival (OS). The multivariate Cox regression analysis identified pERK1/2 as an independent prognostic parameter (P = 0.005). Activation of ERK1/2 in colorectal cancer may indicate aggressive tumor behavior and may constitute an independent prognostic factor. Furthermore, our data suggest that mutations of the k-ras oncogene may induce activation of ERK1/2. We propose immunohistochemical determination of pERK1/2 status as a promising candidate for the identification of high-risk patients who would benefit from new anticancer drugs targeting the ERK pathway.

    Virchows Archiv : an international journal of pathology 2007;450;2;151-9

  • Expansion of the genotypic and phenotypic spectrum in patients with KRAS germline mutations.

    Zenker M, Lehmann K, Schulz AL, Barth H, Hansmann D, Koenig R, Korinthenberg R, Kreiss-Nachtsheim M, Meinecke P, Morlot S, Mundlos S, Quante AS, Raskin S, Schnabel D, Wehner LE, Kratz CP, Horn D and Kutsche K

    Institute of Human Genetics, University of Erlangen-Nuremberg, Germany.

    Background: Noonan syndrome, cardio-facio-cutaneous syndrome (CFC) and Costello syndrome constitute a group of developmental disorders with an overlapping pattern of congenital anomalies. Each of these conditions can be caused by germline mutations in key components of the highly conserved Ras-MAPK pathway, possibly reflecting a similar pathogenesis underlying the three disorders. Germline mutations in KRAS have recently been identified in a small number of patients with Noonan syndrome and CFC.

    260 patients were screened for KRAS mutations by direct sequencing. Overall, we detected KRAS mutations in 12 patients, including three known and eight novel sequence alterations. All mutations are predicted to cause single amino acid substitutions. Remarkably, our cohort of individuals with KRAS mutations showed a high clinical variability, ranging from Noonan syndrome to CFC, and also included two patients who met the clinical criteria of Costello syndrome.

    Conclusion: Our findings reinforce the picture of a clustered distribution of disease associated KRAS germline alterations. We further defined the phenotypic spectrum associated with KRAS missense mutations and provided the first evidence of clinical differences in patients with KRAS mutations compared with Noonan syndrome affected individuals with heterozygous PTPN11 mutations and CFC patients carrying a BRAF, MEK1 or MEK1 alteration, respectively. We speculate that the observed phenotypic variability may be related, at least in part, to specific genotypes and possibly reflects the central role of K-Ras in a number of different signalling pathways.

    Journal of medical genetics 2007;44;2;131-5

  • [Mutational analysis of EGFR and K-RAS in Chinese patients with non-small cell lung cancer].

    Liu F, Jiang B, Gong SJ, Yao BD, Zhang WY, Zhu GS, Zhu ZZ, Gong YF, Wang ML and Hu XH

    Department of Oncology, Third People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 201900 PR China.

    Objective: To investigate gene mutations of the epidermal growth factor receptor (EGFR) and K-RAS in Chinese non-small cell lung cancers (NSCLCs).

    Methods: Mutations of exons 18, 19 and 21 of the EGFR and codons 12, 13 of the K-RAS in 101 NSCLCs were detected by PCR-amplifying and gene sequencing, and the relationship between mutations and clinical characters of NSCLCs and response to gefitinib were analyzed.

    Results: Overall, 26 EGFR mutations (25.7%), 3 K-RAS mutations (2.9%) were detected, and EGFR mutation frequencies in adenocarcinomas, nonsmoker and female were found to be high (44.2%, 65.7% and 48.3% respectively). Nine out of 10 gefitinib treated patients with disease control was found with EGFR mutation.

    Conclusion: The data suggest that mutation frequency of EGFR in NSCLCs from Chinese patients is higher than that of western ethnicities, such mutations are well correlated with tumor response to gefitinib, and gefitinib is more fit for Chinese NSCLC patients.

    Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 2007;24;1;31-4

  • KRAS and BRAF oncogenic mutations in MSS colorectal carcinoma progression.

    Oliveira C, Velho S, Moutinho C, Ferreira A, Preto A, Domingo E, Capelinha AF, Duval A, Hamelin R, Machado JC, Schwartz S, Carneiro F and Seruca R

    Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Porto, Portugal.

    In sporadic colorectal cancer (CRC), KRAS are alternative to BRAF mutations and occur, respectively, in 30 and 10% of cases. Few reports addressed the association between KRAS-BRAF mutations and tumour progression specifically in sporadic microsatellite-stable (MSS) CRC. We screened KRAS and BRAF in 250 MSS primary CRC and 45 lymph node (LN) metastases and analysed the pathological features of the cases to understand the involvement of KRAS-BRAF activation in progression and metastasis. Forty-five per cent of primary MSS CRCs carried mutations in at least one of these genes and mutations were associated with wall invasion (P=0.02), presence and number of LN metastases (P=0.02 and P=0.03, respectively), distant metastases (P=0.004) and advanced stage (P=0.01). We demonstrated that KRAS and BRAF are alternative events in Tis and T1 MSS CRC and, KRAS rather than BRAF mutations, contributed to the progression of MSS CRC. The frequency of KRAS and/or BRAF mutations was higher in LN metastases than in primary carcinomas (P=0.0002). Mutated LN metastases displayed KRAS associated or not with BRAF mutations. BRAF mutations were never present as a single event. Concomitant KRAS and BRAF mutations increased along progression of MSS CRCs, suggesting that activation of both genes is likely to harbour a synergistic effect.

    Oncogene 2007;26;1;158-63

  • Analysis of loss of heterozygosity in atypical and negative bile duct brushing cytology specimens with malignant outcome: are "false-negative" cytologic findings a representation of morphologically subtle molecular alterations?

    Krishnamurti U, Sasatomi E, Swalsky PA, Finkelstein SD and Ohori NP

    Department of Pathology, University of Pittsburgh Medical Center-Presbyterian, Pittsburgh, PA 15213, USA.

    Context: Conventional cytologic evaluation of bile duct brushings for neoplasia has high specificity but relatively low sensitivity.

    Objective: The aim of this pilot study was to examine whether K-ras mutations and loss of heterozygosity for multiple microsatellite markers in bile duct brushings would contribute to the detection of malignancy in cases initially reported as "negative" or "atypical."

    Design: Bile duct brushing specimens with a negative or an atypical cytologic result (9 cases) had a benign result on the surgical pathology specimen, and 9 additional negative or atypical cases demonstrated adenocarcinoma on the resected surgical specimen. Cells from representative cytopathology and histology slides were microdissected and analyzed for K-ras mutations and for loss of heterozygosity with a panel of 15 polymorphic markers on chromosomes 1p, 3p, 5q, 9p, 9q, 10q, 17p, and 22q.

    Results: Among cytology cases with malignant outcome, loss of heterozygosity or K-ras mutation was detected in 8 (88.8%) of 9 cases. In the corresponding 9 surgical pathology specimens with adenocarcinoma, K-ras mutations and/or allelic losses were detected in all (100%). Loss of heterozygosity or K-ras mutation was not detected in cytology cases that had a benign surgical outcome. The fractional allelic loss of these 9 cytology specimens ranged from 0 to 0.25 (mean, 0.14). This compared with the fractional allelic loss ranging from 0.15 to 0.42 (mean, 0.27) for the corresponding surgical specimens.

    Conclusions: This pilot study suggests that low-level fractional allelic loss or K-ras mutation in the negative/atypical cytology samples with malignant outcome is a representation of morphologically subtle molecular alterations.

    Archives of pathology & laboratory medicine 2007;131;1;74-80

  • EGFR and KRAS mutations as criteria for treatment with tyrosine kinase inhibitors: retro- and prospective observations in non-small-cell lung cancer.

    van Zandwijk N, Mathy A, Boerrigter L, Ruijter H, Tielen I, de Jong D, Baas P, Burgers S and Nederlof P

    Department of Thoracic Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands. n.v.zandwijk@nki.nl

    Results of individualized therapy guided by mutational tumor profile of patients with non-small-cell lung cancer are presented. After confirming the importance of epidermal growth factor receptor (EGFR) and KRAS mutations for (non)response on gefitinib in a retrospective series of patients, EGFR mutations were looked for before--and were a condition for--treatment with gefitinib or erlotinib. To increase the chance to find such a mutation, we selected patients on the basis of smoking status, gender and histopathology. Out of 41 patients selected, 13 (32%) were found to harbor an EGFR mutation. In nine of them it concerned deletions in exon 19 and in none of them KRAS mutations were detected. All nine patients with an exon 19 deletion had a favorable and continuing response to tyrosine kinase inhibitors (TKIs), while four other patients with point mutations responded less favorably: stable disease or a response of short duration. These observations confirm the potential role of EGFR and KRAS mutations in predicting (non)response to TKIs. Exon 19 deletions that are associated with the best responses might be used for first-line treatment selection, while KRAS mutations could play a role in excluding patients from treatment with TKIs.

    Annals of oncology : official journal of the European Society for Medical Oncology / ESMO 2007;18;1;99-103

  • Highly conserved sequence of exon 15 BRAF gene and KRAS codon 12 mutation among Greek patients with colorectal cancer.

    Symvoulakis EK, Zaravinos A, Panutsopulos D, Zoras O, Papalambros E, Sigala F and Spandidos DA

    Laboratory of Virology, Medical School, University of Crete, Heraklion, Crete, Greece.

    Background: The RAS/RAF/MEK/MAP kinase pathway is essential to intracellular signaling transduction regulating cell proliferation, differentiation and death. We investigated the occurrence of exon 15 BRAF and KRAS codon 12 mutations among Greek patients with colorectal cancer.

    Methods: Sixty-one samples from patients with sporadic colorectal adenocarcinomas were studied for exon 15 BRAF mutations. DNA from surgically resected specimens was analyzed by a combination of polymerase chain reaction and direct sequencing. KRAS codon 12 mutational analysis was technically possible in 58 samples (58/61) by a combination of polymerase chain reaction and restriction fragment length polymorphism.

    Results: No exon 15 BRAF mutations were detected in any of the colon cancer specimens. The frequency of KRAS codon 12 mutations was 29.3% (17/58). Patients aged < or = 70 years more frequently presented carcinomas harboring KRAS codon 12 mutations than patients aged >70 years (p=0.028). Patients between 61 and 70 years of age were more likely to be carriers of this mutation (p=0.040).

    Conclusions: Despite the limited study sample, our data suggest that BRAF mutations might be present less frequently than KRAS mutations in Greek patients with colorectal carcinomas. Further research involving larger patient series will be necessary to confirm these findings and to assess possible ethnic, environmental and lifestyle influences on BRAF and KRAS mutagenesis.

    The International journal of biological markers 2007;22;1;12-8

  • K-ras mutation and p16 and preproenkephalin promoter hypermethylation in plasma DNA of pancreatic cancer patients: in relation to cigarette smoking.

    Jiao L, Zhu J, Hassan MM, Evans DB, Abbruzzese JL and Li D

    Department of Gastrointestinal Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.

    Objectives: To examine the profiles of K-ras mutations and p16 and preproenkephalin (ppENK) promoter hypermethylation and their associations with cigarette smoking in pancreatic cancer patients.

    Methods: In plasma DNA of 83 patients with untreated primary pancreatic ductal adenocarcinoma, DNA hypermethylation was determined by methylation-specific polymerase chain reaction and K-ras codon 12 mutations by enriched-nested polymerase chain reaction followed by direct sequencing. Information on smoking exposure was collected by in-person interview. Pearson chi test and Fisher exact test were used in statistical analysis.

    Results: K-ras mutations, ppENK, and p16 promoter hypermethylation were detected in 32.5%, 29.3%, and 24.6% of the patients, respectively. Sixty-three percent (52/83) of patients exhibited at least one of the alterations. Smoking was associated with the presence of K-ras mutations (P = 0.003). A codon 12 G-to-A mutation was predominantly observed in regular smokers and in heavy smokers (pack-year of smoking > or =36). Smoking was not associated with p16 or ppENK hypermethylation.

    Conclusions: These preliminary observations suggest that plasma DNA might be a useful surrogate in detecting genetic and epigenetic alterations of pancreatic cancer. The findings on the association between K-ras mutation and smoking were in consistency with previous studies. Further studies on environmental modulators of epigenetic changes in pancreatic cancer are warranted.

    Funded by: NCI NIH HHS: CA16672, CA98380, P30 CA016672, R01 CA098380, R03 CA084581; NIEHS NIH HHS: P30 ES007784, P30 ES07784

    Pancreas 2007;34;1;55-62

  • K-ras mutation detection in colorectal cancer using the Pyrosequencing technique.

    Poehlmann A, Kuester D, Meyer F, Lippert H, Roessner A and Schneider-Stock R

    Department of Pathology, Otto-von-Guericke University, Magdeburg, Germany.

    The identification of gene mutations is a critical goal for the assessment of diagnosis and prognosis in cancer disease, particularly by direct sequencing. Pyrosequencing is a straightforward, non-electrophoretic DNA sequencing method using the luciferase-luciferin light release as a signal for nucleotide incorporation into a PCR template DNA. In this study, we aimed to investigate mutations in the K-ras gene using Pyrosequencing technology, because its reliable chemistry and robust detection mechanism allow for rapid, real-time detection of sequencing events. For the simultaneous detection of the predominant K-ras codons 12 and 13 mutations, we established a sequencing protocol based on the design of a single PCR primer pair and a single sequencing primer. The assay has been validated with DNA from 65 colorectal carcinomas. Furthermore, analysis of the rare K-ras codon 61 mutation was included. In 29% (19/65) of the patients, the K-ras gene was found to be mutated, whereas codons 12 and 13 were most frequently affected (18/65, 27.7%). Mutations with the highest frequency were G-->A transitions (12/19, 63%), followed by G-->T transversions (5/19, 26%). Overall survival was significantly shorter in patients with a tumor containing K-ras codon 12 mutations than in those without K-ras codon 12 mutations (p=0.024). In conclusion, we found Pyrosequencing to be a suitable technology for fast detection of hot-spot mutations in the K-ras oncogene. We demonstrated an important relationship between K-ras codon 12 mutations and overall survival in colorectal cancer patients.

    Pathology, research and practice 2007;203;7;489-97

  • Phenotype of bone metastases of non-small cell lung cancer: epidermal growth factor receptor expression and K-RAS mutational status.

    Badalian G, Barbai T, Rásó E, Derecskei K, Szendrôi M and Tímár J

    Department of Orthopedics, Semmelweis University, Budapest, Hungary.

    Bone metastasis is a frequent complication of lung cancer progression, however, studies on bone metastatic tissues are scanty. Here we have collected a small cohort of 11 non-small cell lung cancer cases where primary tumors and corresponding bone metastases were available for pathological analysis. We have tested two molecular markers: EGFR protein expression and K-RAS mutation at codon 12 using immunohistochemistry and RFLPPCR, respectively. We have shown that using improved protocols, EGFR protein (both the extracellular as well as the cytoplasmic domain) is readily detectable in decalcified bone tissue. We found that the EGFR expression status is highly similar in bone metastases compared to the primary tumors, although the expression levels may change. Individual comparison of corresponding primary and metastatic NSCLC tissues indicated that downregulation of EGFR was a rare event (2/11) compared to upregulation (4/11) in bone metastases. On the other hand, our data indicate that the K-RAS mutational status of the primary tumor does not predict the status of the bone metastatic tissue of NSCLC, since we have observed both emergence of mutant clones in metastases from wild-type (wt) primary tumors and loss of mutant clones in metastases from mutant primaries in addition to the maintained mutant status. Our data support that at least two progression models occur in NSCLC, the samegene as well as the clonal selection one. It is noteworthy that in NSCLC cases with wt- or mutant KRAS, downregulation of EGFR expression was a rare event although upregulation in bone metastases was observed more frequently in wt K-RAS cases.

    Pathology oncology research : POR 2007;13;2;99-104

  • High resolution melting analysis for the rapid and sensitive detection of mutations in clinical samples: KRAS codon 12 and 13 mutations in non-small cell lung cancer.

    Krypuy M, Newnham GM, Thomas DM, Conron M and Dobrovic A

    Molecular Pathology Research Laboratory, Peter MacCallum Cancer Centre, Locked Bag 1, A'Beckett St, Melbourne, Victoria 8006, Australia. michael.krypuy@petermac.org <michael.krypuy@petermac.org&gt;

    Background: The development of targeted therapies has created a pressing clinical need for the rapid and robust molecular characterisation of cancers. We describe here the application of high-resolution melting analysis (HRM) to screen for KRAS mutations in clinical cancer samples. In non-small cell lung cancer, KRAS mutations have been shown to identify a group of patients that do not respond to EGFR targeted therapies and the identification of these mutations is thus clinically important.

    Methods: We developed a high-resolution melting (HRM) assay to detect somatic mutations in exon 2, notably codons 12 and 13 of the KRAS gene using the intercalating dye SYTO 9. We tested 3 different cell lines with known KRAS mutations and then examined the sensitivity of mutation detection with the cell lines using 189 bp and 92 bp amplicons spanning codons 12 and 13. We then screened for KRAS mutations in 30 non-small cell lung cancer biopsies that had been previously sequenced for mutations in EGFR exons 18-21.

    Results: Known KRAS mutations in cell lines (A549, HCT116 and RPMI8226) were readily detectable using HRM. The shorter 92 bp amplicon was more sensitive in detecting mutations than the 189 bp amplicon and was able to reliably detect as little as 5-6% of each cell line DNA diluted in normal DNA. Nine of the 30 non-small cell lung cancer biopsies had KRAS mutations detected by HRM analysis. The results were confirmed by standard sequencing. Mutations in KRAS and EGFR were mutually exclusive.

    Conclusion: HRM is a sensitive in-tube methodology to screen for mutations in clinical samples. HRM will enable high-throughput screening of gene mutations to allow appropriate therapeutic choices for patients and accelerate research aimed at identifying novel mutations in human cancer.

    BMC cancer 2006;6;295

  • Activation of Ras/Raf protects cells from melanoma differentiation-associated gene-5-induced apoptosis.

    Lin L, Su Z, Lebedeva IV, Gupta P, Boukerche H, Rai T, Barber GN, Dent P, Sarkar D and Fisher PB

    Department of Pathology, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, College of Physicians and Surgeons, New York, NY 10032, USA.

    Melanoma differentiation-associated gene-5 (mda-5) was the first molecule identified in nature whose encoded protein embodied the unique structural combination of an N-terminal caspase recruitment domain and a C-terminal DExD/H RNA helicase domain. As suggested by its structure, cumulative evidences documented that ectopic expression of mda-5 leads to growth inhibition and/or apoptosis in various cell lines. However, the signaling pathways involved in mda-5-mediated killing have not been elucidated. In this study, we utilized either genetically modified cloned rat embryo fibroblast cells overexpressing different functionally and structurally distinct oncogenes or human pancreatic and colorectal carcinoma cells containing mutant active ras to resolve the role of the Ras/Raf signaling pathway in mda-5-mediated growth inhibition/apoptosis induction. Rodent and human tumor cells containing constitutively activated Raf/Raf/MEK/ERK pathways were resistant to mda-5-induced killing and this protection was antagonized by intervening in this signal transduction cascade either by directly inhibiting ras activity using an antisense strategy or by targeting ras-downstream factors, such as MEK1/2, with the pharmacological inhibitor PD98059. The present findings provide a further example of potential cross-talk between growth-inhibitory and growth-promoting pathways in which the ultimate balance of these factors defines cellular homeostasis, leading to survival or induction of programmed cell death.

    Funded by: NIGMS NIH HHS: GM068848

    Cell death and differentiation 2006;13;11;1982-93

  • Growth regulation via insulin-like growth factor binding protein-4 and -2 in association with mutant K-ras in lung epithelia.

    Sato H, Yazawa T, Suzuki T, Shimoyamada H, Okudela K, Ikeda M, Hamada K, Yamada-Okabe H, Yao M, Kubota Y, Takahashi T, Kamma H and Kitamura H

    Department of Pathobiology, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanagawa, Japan.

    Gain-of-function point mutations in K-ras affect early events in pulmonary bronchioloalveolar carcinoma. We investigated altered mRNA expression on K-Ras activation in human peripheral lung epithelial cells (HPL1A) using oligonucleotide microarrays. Mutated K-Ras stably expressed in HPL1A accelerated cell growth and induced the expression of insulin-like growth factor (IGF)-binding protein (IGFBP)-4 and IGFBP-2, which modulate cell growth via IGF. Other lung epithelial cell lines (NHBE and HPL1D) revealed the same phenomena as HPL1A by mutated K-ras transgene. Lung cancer cell growth was also accelerated by mutated K-ras gene transduction, whereas IGFBP-4/2 induction was weaker compared with mutated K-Ras-expressing lung epithelial cells. To understand the differences in IGFBP-4/2 inducibility via K-Ras-activated signaling between nonneoplastic lung epithelia and lung carcinoma, we addressed the mechanisms of IGFBP-4/2 transcriptional activation. Our results revealed that Egr-1, which is induced on activation of Ras-mitogen-activated protein kinase signaling, is crucial for transactivation of IGFBP-4/2. Furthermore, IGFBP-4 and IGFBP-2 promoters were often hypermethylated in lung carcinoma, yielding low basal expression/weak induction of IGFBP-4/2. These findings suggest that continuous K-Ras activation accelerates cell growth and evokes a feedback system through IGFBP-4/2 to prevent excessive growth. Moreover, this growth regulation is disrupted in lung cancers because of promoter hypermethylation of IGFBP-4/2 genes.

    The American journal of pathology 2006;169;5;1550-66

  • Knockdown of mutant K-ras expression by adenovirus-mediated siRNA inhibits the in vitro and in vivo growth of lung cancer cells.

    Zhang Z, Jiang G, Yang F and Wang J

    Department of Thoracic Surgery, People's Hospital, Peking University, Beijing, PR, China. zhangzhiping1990@sina.com <zhangzhiping1990@sina.com&gt;

    The ras mutation, which is observed in 20-30% of human nonsmall cell lung cancers (NSCLCs), is one of common genetic alterations and has been proposed to be a prognostic factor in lung cancer. Oncogene ras appears to be essential for tumor progression and maintenance. Several therapeutic agents have been developed to inhibit ras, such as FTIs and antisense oligonucleotides. A new tool for blocking oncogenes in cancer cells has emerged with the discovery that RNA interference can specifically silence expression of endogenous human genes. In the current study, we used small interfering RNA (siRNA) directed against mutant K-ras to determine the anti-tumor effects of decreasing the levels of this protein in lung cancer cell lines. Adenovirus-mediated siRNA (AdH1/siK-ras(V12)) against K-ras(V12) markedly decreased K-ras(V12) gene expression and inhibited cellular proliferation of NSCLC H441 cells that express the relevant mutation (K-ras codon 12 GGT --> GTT), but produced minimal growth inhibition on NSCLC H1650 cells that lack the relevant mutation. Pretreatment with AdH1/siK-ras(V12) completely abrogated subcutaneous engraftment of H441 cells, as compared with a 100% tumor take in animals that received control vector-treated tumor cells. The in vivo effect of AdH1/siK-ras(V12) treatment was further examined by intratumoral injections after tumor induction. Pre-existing tumor growth was reduced by 45% by a single intratumoral injection. Three or five repeat injections resulted in complete tumor regression in eight of ten nude mice. Further, 23.12% of AdH1/siK-ras(V12) treated H441 cells underwent apoptosis, as compared with 6.13%, and 8.27% in untreated and control vector-treated cells, respectively. These results indicate that adenovirus-mediated siRNA can specifically and efficiently target factors whose expression is altered in malignancy and may have the potential as a therapeutic modality to treat human lung cancer.

    Cancer biology & therapy 2006;5;11;1481-6

  • KRAS variation and risk of endometriosis.

    Zhao ZZ, Nyholt DR, Le L, Martin NG, James MR, Treloar SA and Montgomery GW

    Molecular Epidemiology Laboratory and Genetic Epidemiology Laboratory, Queensland Institute of Medical Research, Brisbane, Queensland, Australia.

    Endometriosis is a common gynaecological disease with symptoms of pelvic pain and infertility which affects 7-10% of women in their reproductive years. Activation of an oncogenic allele of Kirsten rat sarcoma viral oncogene homologue (KRAS) in the reproductive tract of mice resulted in the development of endometriosis. We hypothesized that variation in KRAS may influence risk of endometriosis in humans. Thirty tagSNPs spanning a region of 60.7 kb across the KRAS locus were genotyped using iPLEX chemistry on a MALDI-TOF MassARRAY platform in 959 endometriosis cases and 959 unrelated controls, and data were analysed for association with endometriosis. Genotypes were obtained for most individuals with a mean completion rate of 99.1%. We identified six haplotype blocks across the KRAS locus in our sample. There were no significant differences between cases and controls in the frequencies of individual single-nucleotide polymorphisms (SNPs) or haplotypes. We also developed a rapid method to screen for 11 common KRAS and BRAF mutations on the Sequenom MassARRAY system. The assay detected all mutations previously identified by direct sequencing in a panel of positive controls. No germline variants for KRAS or BRAF were detected. Our results demonstrate that any risk of endometriosis in women because of common variation in KRAS must be very small.

    Molecular human reproduction 2006;12;11;671-6

  • NF-kappaB inhibition increases chemosensitivity to trichostatin A-induced cell death of Ki-Ras-transformed human prostate epithelial cells.

    Kwon O, Kim KA, Kim SO, Ha R, Oh WK, Kim MS, Kim HS, Kim GD, Kim JW, Jung M, Kim CH, Ahn JS and Kim BY

    Laboratory of Cellular Signaling Modulators, Korea Research Institute of Bioscience and Biotechnology (KRIBB) Yuseong, Daejeon, 305-333, Korea.

    Chemoresistance has been one of the major problems in anticancer therapy. In our effort to find a potential molecular target for overcoming the chemoresistance in prostate cancer, a promising anticancer drug trichostatin A (TSA) induced cell death was found to be compromised by enhanced NF-kappaB activation in 267B1/K-ras human prostate epithelial cancer cells. However, both the NF-kappaB activation and chemoresistance were reduced by pretreatment with proteasome inhibitor-I (ProI), accompanied by accumulations of both IkappaBalpha and p65/RelA (but not p50/NF-kappaB1) in the cytoplasm. Clonogenic cell survival and soft agar assays further confirmed the increased TSA chemosensitivity of 267B1/K-ras cells by ProI treatment. Moreover, dominant negative mutant of IKKbeta, IkappaBalpha and p65 enhanced the chemosensitization, too. Unexpectedly, using LY294002 and PD98059, phosphatidylinositol-3-kinase and mitogen-activated protein kinase were also implied in TSA chemoresistance through NF-kappaB activation, while these compounds had showed no effect on radiosensitization in the cells. On the other hand, together with TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) assay, activations of caspase-8 and caspase-3 by TSA and ProI were noticed, suggesting the involvement of apoptotic process in chemosensitization of 267B1/K-ras cells. Altogether, these results suggest that blocking the NF-kappaB activation pathway could be an efficient target for improving the TSA chemosensitization and applying to the development of anticancer therapeutics in Ki-Ras-overexpressing tumorigenic cells, including prostate cancer.

    Carcinogenesis 2006;27;11;2258-68

  • BRAF and KRAS mutations in prostatic adenocarcinoma.

    Cho NY, Choi M, Kim BH, Cho YM, Moon KC and Kang GH

    Laboratory of Epigenetics, Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.

    Constitutive activation of the kinase cascade involving RAS, RAF, MEK and ERK is common to human cancers, and mutations of KRAS and BRAF are mutually exclusive and serve as alternatives to activate the RAS/RAF/ERK signaling pathway. RAS mutations are known to occur in prostate adenocarcinomas, but little is known about BRAF mutations in these tumors. In the present study, BRAF and KRAS mutations were characterized in 206 prostate adenocarcinomas by enhanced PCR-RFLP and direct sequencing. The identified KRAS and BRAF mutations were then analyzed with respect to preoperative serum PSA levels, Gleason scores and tumor stages. Mutations in codon 600 of BRAF were identified in 21 (10.2%) of 206 prostate adenocarcinomas. KRAS mutations in codons 12 or 13 were found in 15 (7.3%) of 206 prostate adenocarcinomas. However, no tumor specimen contained both BRAF and KRAS mutations. Prostate adenocarcinomas with a BRAF mutation tended to show higher preoperative serum PSA levels, Gleason scores and tumor stages than prostate adenocarcinomas with a KRAS mutation. The results obtained show that BRAF mutations are as uncommon as KRAS mutations in prostate adenocarcinoma. Although BRAF and KRAS are members of the same RAS/ERK signaling pathway, prostate adenocarcinomas with a BRAF mutation showed clinicopathologic features that differed from those of prostate adenocarcinoma with a KRAS mutation.

    International journal of cancer. Journal international du cancer 2006;119;8;1858-62

  • Nore1B regulates TCR signaling via Ras and Carma1.

    Ishiguro K, Avruch J, Landry A, Qin S, Ando T, Goto H and Xavier R

    Department of Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.

    Nore1A was originally identified as a potential Ras effector, and Nore1B is an alternatively spliced isoform. Both share a Ras/Rap association domain (RA domain) but only Nore1A contains sequence motifs that predict SH3 domain binding and diacylglycerol/phorbol ester binding in the amino-terminal region. Here we report that Carma1 binds to Nore1A and Nore1B through the RA domain and that Carma1 interacts with active Ras in the presence of Nore1B. RNA interference against Nore1B attenuates NF-kappaB activation induced by T cell receptor (TCR) ligation, but not NF-kappaB activation induced by TNFalpha or lipoteichoic acid. In addition, Nore1B is also required for KiRas GV12-mediated ERK1 activation and Elk1 reporter activity in T cells. We also provide evidence that knockdown of Nore1B also impairs polarized redistribution of Ras at the B cell-T cell immune interface. Together, these findings suggest that endogenous Nore1B recruits active Ras to the APC-T cell interface and mediates the interaction between Ras and Carma1.

    Funded by: NIDDK NIH HHS: DK43351, P30 DK040561-11

    Cellular signalling 2006;18;10;1647-54

  • K-Ras4B proteins are expressed in the nucleolus: Interaction with nucleolin.

    Birchenall-Roberts MC, Fu T, Kim SG, Huang YK, Dambach M, Resau JH and Ruscetti FW

    Basic Research Program, SAIC-Frederick, Inc., National Cancer Institute at Frederick, Frederick, MD 2170, USA. birchena@mail.ncifcrf.gov

    Kirsten Ras4B (K-Ras4B) is a potent onco-protein that is expressed in the majority of human cell types and is frequently mutated in carcinomas. K-Ras4B, like other members of the Ras family of proteins, is considered to be a cytoplasmic protein that must be localized to the plasma membrane for activation. Here, using confocal microscopy and biochemical analysis, we show that K-Ras4B, but not H-Ras or the closely related K-Ras4A, is also present in the nucleoli of normal and transformed cells. Subcellular fractionation and immunostaining show that K-Ras4B is located not only in the cytoplasm, but also in the nucleolar compartment. Modification of a C-terminal hexa-lysine motif unique to K-Ras4B results in exclusively cytoplasmic forms of the protein. Nucleolin, a pleiotropic regulator of cellular processes, including transcriptional regulation, is also characterized by a nucleolar-like nuclear appearance. We show that K-Ras4B and nucleolin co-localize within the nucleus and that nucleolin physically associates with K-Ras4B. Inhibition of K-Ras4B/nucleolin association blocked nucleolar localization of K-Ras4B. Using siRNA to knockdown the expression of nucleolin eliminated the nucleolar localization of K-Ras4B and significantly repressed the activation of the well-characterized K-Ras4B transcriptional target Ap-1, but stimulated Elk1. These data provide evidence of a nucleolar localization of K-Ras4B and describe a functional association between K-Ras4B and nucleolin.

    Funded by: Intramural NIH HHS; NCI NIH HHS: N01-CO-12400

    Biochemical and biophysical research communications 2006;348;2;540-9

  • The expression of the homologue of the Caenorhabditis elegans lin-45 raf is regulated in the motile stages of the plant parasitic nematode Meloidogyne artiellia.

    Cortese MR, Di Vito M and De Giorgi C

    Dipartimento di Biochimica e Biologia Molecolare, Via Orabona 4, 70126 Bari, Italy.

    The Ras-MAPK signal transduction pathway controls multiple developmental events and is involved in the processing of olfactory information in the free living nematode Caenorhabditis elegans. We have studied the Ras-MAPK pathway in the plant parasitic nematode Meloidogyne artiellia. The genes Mt-let-60, Mt-lin-45, Mt-mek-2 and Mt-mpk-1 have been isolated and sequenced. Each of them shows a high level of sequence similarity to its presumed ortholog in C. elegans and key functional domains are structurally conserved. Furthermore, we show that the M. artiellia recombinant MEK-2 protein can phosphorylate and activate the M. artiellia recombinant MPK-1 and the recombinant MEK-2 itself can be phosphorylated and activated by immunoprecipitated mammalian Raf. Surprisingly, the Mt-lin-45 message is not detectable in freshly emerged juveniles or in male specimens, suggesting that it may be quickly degraded in these life stages.

    Molecular and biochemical parasitology 2006;149;1;38-47

  • Mutation and polymorphism in the EGFR-TK domain associated with lung cancer.

    Zhang W, Stabile LP, Keohavong P, Romkes M, Grandis JR, Traynor AM and Siegfried JM

    Department of Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213-1863, USA.

    Background: The epidermal growth factor receptor (EGFR) is involved in the development and progression of lung cancer. Somatic EGFR mutations are predictors of response to treatment with EGFR tyrosine kinase (TK) inhibitors (TKIs) for lung cancer, especially among never smokers. EGFR mutations may occur independently of other genetic alterations.

    Methods: The authors sequenced the EGFR-TK domain and the K-ras and p53 genes from lung tumor tissues from 44 never smokers and 46 smokers. A case-control study also was conducted to examine the relationship between an EGFR single nucleotide polymorphism in the TK domain and the lung cancer through a multivariate logistic regression analysis. In addition, the authors compared cell growth kinetics, EGFR-TKI sensitivity by MTT, and activation of signaling molecules by immunoblot in lung cancer cell lines with and without EGFR-TK mutations.

    Results: EGFR-TK mutations were more frequently observed in never smokers (25%) than in smokers (2.2%) (p = 0.001). Excluding cases with a K-ras mutation, the frequency of EGFR-TK domain mutation was still significantly higher in never smokers than in smokers, 26.2% versus 4.5% (p = 0.046). EGFR-TK mutations and K-ras mutations (p = 0.015), and p53 and K-ras mutations (p = 0.015) were mutually exclusive, but p53 and EGFR-TK mutations were not (p = 1.00). During sequencing of the EGFR-TK domain in tumors, an EGFR polymorphism (G2607A) was identified. The genotype AA and AA + AG occurred at a significantly higher frequency in lung cancer cases (n = 122) when compared with controls (n = 147) (odds ratio, 3.39 and 2.67; 95% confidence interval, 1.41-8.17 and 1.17-6.08, p = 0.006 and p = 0.02, respectively). This polymorphism was found independently of EGFR-TK mutations in lung cancer cases, indicating that it does not predispose to mutations. In vitro, lung cancer cell lines with EGFR-TK mutations also did not contain K-ras mutations and displayed a lower growth rate (50%, p = 0.013) than EGFR-TK wild-type cell lines. EGFR-TK mutant cell lines were more sensitive to both gefitinib and erlotinib, although relative sensitivity to erlotinib compared with wild-type was less pronounced than for gefitinib. Cell lines with a lower growth rate also expressed higher levels of E-cadherin than faster growing cell lines.

    Conclusions: EGFR-TK mutation frequency is high in never-smoking lung cancer patients and is exclusive of mutation in K-ras but not p53. In addition to somatic EGFR-TK mutations that arise in lung tumors, germline variation in the EGFR-TK domain might also be associated with an increased risk of lung cancer. Somatic EGFR-TK mutations alter cell biology and response to EGFR-TKIs and may be mutation specific.

    Funded by: NCI NIH HHS: 5R25 CA89507, CA9045440

    Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer 2006;1;7;635-47

  • BRAF, K-ras and BAT26 mutations in colorectal polyps and stool.

    Jin YM, Li BJ, Qu B and Du YJ

    Department of Gastroenterology, Second Affiliated Hospital of Harbin Medical University, Harbin 150086, Heilongjiang Province, China.

    Aim: To assess the feasibility of using BRAF, K-ras and BAT26 genes as stool-based molecular markers for detection of colorectal adenomas and hyperplastic polyps (HPs).

    Methods: We applied PCR-SSCP and direct sequencing to detect BRAF mutations of polyps and paired stool samples. Primer-mediated restriction fragment length polymorphism (RFLP) analysis and mutant-enriched PCR were used in detection of K-ras mutations of polyp tissues and paired stool samples respectively. BAT26, a microsatellite instability marker was examined by detection of small unstable alleles in a poly (A) repeat.

    Results: No genetic alterations were detected in the 36 colonoscopically normal patients in either tissues or stools. BRAF, K-ras and BAT26 mutations were found in 4 (16%), 10 (40%) and 3 (12%) of 25 adenoma tissues and among them, 75%, 80% and 100% of patients were observed to contain the same mutations in their corresponding stool samples. In HPs, mutations of BRAF and K-ras were detected in the tumor DNA of 2 (11.1%) and 8 (33.3%) of 18 patients respectively, all of whom had identical alterations in their stools. Taken together, the three genetic markers detected 15 (60%) of 25 adenomas and 8 (44.4%) of 18 HPs. The sensitivity of stool detection was 80% for adenomas and 100% for HPs with an overall specificity of 92% for adenomas and 100% for HPs.

    Conclusion: BRAF, K-ras and BAT26 genes have the potential to be molecular markers for colorectal adenomas and HPs, and can be used as non-invasive screening markers for colorectal polyps.

    World journal of gastroenterology : WJG 2006;12;32;5148-52

  • Advanced colorectal polyps with the molecular and morphological features of serrated polyps and adenomas: concept of a 'fusion' pathway to colorectal cancer.

    Jass JR, Baker K, Zlobec I, Higuchi T, Barker M, Buchanan D and Young J

    Department of Pathology, McGill University, Montreal, Canada. jeremy.jass@mcgill.ca

    Aim: To establish and explain the pattern of molecular signatures across colorectal polyps.

    Thirty-two sessile serrated adenomas (SSA), 10 mixed polyps (MP), 15 traditional serrated adenomas (SA), 49 hyperplastic polyps (HP) and 84 adenomas were assessed for mutation of KRAS and BRAF and aberrant expression of p53. The findings were correlated with loss of expression of O-6-methylguanine DNA methyltransferase (MGMT). KRAS mutation occurred more frequently (26.5%) than BRAF mutation (4.8%) in adenomas (P < 0.001) and particularly in adenomas with villous architecture (50%). Loss of expression of MGMT correlated with KRAS mutation in small tubular adenomas (P < 0.04). BRAF mutation was frequent in HPs (67%) and SSAs (81%), while KRAS mutation was infrequent (4% and 3%, respectively). Of MPs and SAs, 72% had either BRAF or KRAS mutation. Aberrant expression of p53 was uncommon overall, but occurred more frequently in MPs and SAs (12%) than adenomas (1%) (P < 0.04) and there was concordant loss of expression of MGMT.

    Conclusions: Molecular alterations that are characteristic of the serrated pathway and adenoma-carcinoma sequence can co-occur in a minority of advanced colorectal polyps that then show morphological features of both pathways. These lesions account for only 2% of colorectal polyps, but may be relatively aggressive.

    Histopathology 2006;49;2;121-31

  • Associations of Ki-ras proto-oncogene mutation and p53 gene overexpression in sporadic colorectal adenomas with demographic and clinicopathologic characteristics.

    Einspahr JG, Martinez ME, Jiang R, Hsu CH, Rashid A, Bhattacharrya AK, Ahnen DJ, Jacobs ET, Houlihan PS, Webb CR, Alberts DS and Hamilton SR

    Department of Medicine, Arizona Cancer Center, P.O. Box 245024, Tucson, AZ 85724, USA. jeinspahr@azcc.arizona.edu

    In colorectal tumorigenesis, Ki-ras proto-oncogene mutation often occurs early in the adenoma-adenocarcinoma sequence, whereas mutation of the p53 gene is associated with late progression to carcinoma. We evaluated the relationship of demographic and clinicopathologic characteristics to Ki-ras mutation and p53 gene product overexpression in 1,093 baseline sporadic colorectal adenomas from 926 individuals enrolled in a phase III recurrence prevention trial. Ki-ras mutation was found in 14.7% of individuals and p53 overexpression was found in 7.0% of those tested. Multivariate analysis found older age, rectal location, and villous histology to be independently associated with Ki-ras mutation. Individuals with an advanced adenoma (>or=1 cm or high-grade dysplasia or villous histology) had a 4-fold higher likelihood of Ki-ras mutation [odds ratios (OR), 3.96; 95% confidence intervals (CI), 2.54-6.18]. Ki-ras mutations in codon 12 and of the G-to-A transition type were more frequent in older individuals, whereas G-to-T transversion was more frequent in rectal adenomas than in the colon. Multivariate analysis showed that previous history of a polyp (P = 0.03) was inversely associated with p53 overexpression. Large adenoma size (>or=1 cm), high-grade dysplasia, and villous histology were independently associated with p53 overexpression, with the strongest association for advanced adenomas (OR, 7.20; 95% CI, 3.01-17.22). Individuals with a Ki-ras mutated adenoma were more likely to overexpress p53 (OR, 2.46; 95% CI, 1.36-4.46), and 94.8% of adenomas with both alterations were classified as advanced (P <or= 0.0001). Our large cross-sectional study supports the role of both Ki-ras and p53 in the progression of adenomas and shows that their molecular pathogenesis differs by anatomic location, age, and mucosal predisposition as evidenced by previous history of a polyp.

    Funded by: NCI NIH HHS: CA16672, CA23074, CA41108, P01 CA041108, P30 CA016672, P30 CA023074

    Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 2006;15;8;1443-50

  • Oncogenic K-Ras down-regulates Rac1 and RhoA activity and enhances migration and invasion of pancreatic carcinoma cells through activation of p38.

    Dreissigacker U, Mueller MS, Unger M, Siegert P, Genze F, Gierschik P and Giehl K

    Department of Pharmacology and Toxicology, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany.

    Activating mutations in the K-ras gene are genetic alterations frequently found in human carcinomas, particularly in pancreatic adenocarcinomas. Mutation of the K-ras gene is thought to be an early and important event in pancreatic tumor initiation, but the precise role of the mutant K-Ras proteins in neoplastic progression is still unknown. In the present study, we have characterized the influence of oncogenic K-Ras on the phenotype and on the signal transduction of epitheloid PANC-1 pancreatic carcinoma cells by generating PANC-1 cell clones, which stably express EGFP(enhanced green fluorescent protein)-K-Ras (V12). EGFP-K-Ras (V12)-expressing cells exhibited a more fibroblastoid cellular phenotype with irregular cell shape and disorganized cytokeratin filaments. Moreover, these cells showed a marked enhancement of their migratory and invasive properties. Stable expression of EGFP-K-Ras (V12) down-regulated the activity of Rac1 and RhoA, resulting in reduced subcortical actin filaments and stress fibers, which might contribute to the epithelial dedifferentiation. Characterization of the activity of mitogen-activated protein kinases revealed that EGFP-K-Ras (V12) enhanced the activity of p38, but did not affect the activities of the Raf/MEK/ERK cascade and JNK. While inhibition of either MEK or JNK activity had no effect on EGFP-K-Ras (V12)-induced migration, inhibition of p38 activity markedly reduced EGFP-K-Ras (V12)-induced migration. Collectively, the results suggest that oncogenic K-Ras enhances the malignant phenotype and identify the mitogen-activated protein kinase p38 as a target to inhibit oncogenic K-Ras-induced pancreatic tumor cell migration.

    Cellular signalling 2006;18;8;1156-68

  • Recurrent KRAS codon 146 mutations in human colorectal cancer.

    Edkins S, O'Meara S, Parker A, Stevens C, Reis M, Jones S, Greenman C, Davies H, Dalgliesh G, Forbes S, Hunter C, Smith R, Stephens P, Goldstraw P, Nicholson A, Chan TL, Velculescu VE, Yuen ST, Leung SY, Stratton MR and Futreal PA

    Cancer Genome Project, Welcome Trust Sanger Institute, Hinxton, UK.

    An activating point mutation in codon 12 of the HRAS gene was the first somatic point mutation identified in a human cancer and established the role of somatic mutations as the common driver of oncogenesis. Since then, there have been over 11,000 mutations in the three RAS (HRAS, KRAS and NRAS) genes in codons 12, 13 and 61 reported in the literature. We report here the identification of recurrent somatic missense mutations at alanine 146, a highly conserved residue in the guanine nucleotide binding domain. In two independent series of colorectal cancers from Hong Kong and the United States we detected KRAS A146 mutations in 7/126 and 2/94 cases, respectively, giving a combined frequency of 4%. We also detected KRAS A146 mutations in 2/40 (5%) colorectal cell lines, including the NCI-60 colorectal cancer line HCC2998. Codon 146 mutations thus are likely to make an equal or greater contribution to colorectal cancer than codon 61 mutations (4.2% in our combined series, 1% in the literature). Lung adenocarcinomas and large cell carcinomas did not show codon 146 mutations. We did, however, identify a KRAS A146 mutation in the ML-2 acute myeloid leukemia cell line and an NRAS A146 mutation in the NALM-6 B-cell acute lymphoblastic leukemia line, suggesting that the contribution of codon 146 mutations is not entirely restricted to colorectal cancers or to KRAS.

    Funded by: NCI NIH HHS: CA062924, CA121113, P50 CA062924, R01 CA121113; Wellcome Trust: 077012

    Cancer biology & therapy 2006;5;8;928-32

  • TP53 and KRAS2 mutations in plasma DNA of healthy subjects and subsequent cancer occurrence: a prospective study.

    Gormally E, Vineis P, Matullo G, Veglia F, Caboux E, Le Roux E, Peluso M, Garte S, Guarrera S, Munnia A, Airoldi L, Autrup H, Malaveille C, Dunning A, Overvad K, Tjønneland A, Lund E, Clavel-Chapelon F, Boeing H, Trichopoulou A, Palli D, Krogh V, Tumino R, Panico S, Bueno-de-Mesquita HB, Peeters PH, Pera G, Martinez C, Dorronsoro M, Barricarte A, Navarro C, Quirós JR, Hallmans G, Day NE, Key TJ, Saracci R, Kaaks R, Riboli E and Hainaut P

    IARC, 150 Cours Albert Thomas, 69372 Lyon Cedex 08, France.

    In cancer patients, plasma often contains mutant DNA released by cancer cells. We have assessed the significance of plasma DNA mutations for subsequent cancer development in healthy subjects in a large longitudinal prospective study. The European Prospective Investigation into Cancer and Nutrition study was analyzed with a nested case-control design. Cases were nonsmokers or ex-smokers for >10 years and newly diagnosed with lung, bladder, or upper aerodigestive tract cancers or leukemia accrued after a median follow-up of 6.3 years. Controls were matched 2:1 for follow-up, age, sex, area of recruitment, and smoking status. KRAS2 mutations were detected by mutant-enriched PCR and sequencing (n = 1,098). TP53 mutations were detected by denaturing high-performance liquid chromatography, temporal temperature gradient electrophoresis, and sequencing (n = 550). KRAS2 or TP53 mutations were detected in 13 of 1,098 (1.2%) and 20 of 550 (3.6%) subjects, respectively, 16 of whom developed cancer on average after 18.3 months of follow-up. Among 137 subjects who developed bladder cancer, 5 had KRAS2 mutations [odds ratio (OR), 4.25; 95% confidence interval (95% CI), 1.27-14.15] and 7 had TP53 mutations (OR, 1.81; 95% CI, 0.66-4.97). There was a nonsignificant trend for association between TP53 mutations and bulky adducts in lymphocyte DNA (OR, 2.78; 95% CI, 0.64-12.17). This is the first report of TP53 or KRAS2 mutations in the plasma of healthy subjects in a prospective study, suggesting that KRAS2 mutation is detectable ahead of bladder cancer diagnosis. TP53 mutation may be associated with environmental exposures. These observations have implications for monitoring early steps of carcinogenesis.

    Funded by: Wellcome Trust

    Cancer research 2006;66;13;6871-6

  • Detection of N-RAS and K-RAS in their active GTP-bound form in acute myeloid leukemia without activating RAS mutations.

    Ehmann F, Horn S, Garcia-Palma L, Wegner W, Fiedler W, Giehl K, Mayr GW and Jücker M

    Center of Experimental Medicine, Institute of Biochemistry and Molecular Biology I, Cellular Signal Transduction, University Hospital Hamburg-Eppendorf, Hamburg, Germany.

    RAS genes, predominantly N-RAS and K-RAS, have been implicated in the pathogenesis of acute myeloid leukemia (AML), due to activating RAS mutations detectable in approximately 20% of AML patients. In the present study, RAS proteins were detected in their activated, GTP-bound form, in AML patients (n = 10) not expressing mutated forms of H-RAS, K-RAS and N-RAS. Further analysis revealed the simultaneous presence of N-RAS and K-RAS proteins in the GTP-bound state in seven out of 10 AML samples. In four out of 10 samples the levels of RAS-GTP were comparable to an AML cell line (TF-1) with an activating N-RAS mutation (Q61P). The detection of RAS-GTP in AML patients without RAS mutations further supports a functional role of RAS proteins in the pathogenesis of AML and may explain the observed effects of RAS inhibitors in some AML patients in the absence of activating RAS mutations.

    Leukemia & lymphoma 2006;47;7;1387-91

  • Frequency of RAS gene mutation and its cooperative genetic events in Southeast Asian adult acute myeloid leukemia.

    Auewarakul CU, Lauhakirti D and Tocharoentanaphol C

    Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand. cicaw@mahidol.ac.th

    RAS gene as one of the most frequently mutated genes in acute myeloid leukemia (AML) has become an attractive target for molecular therapy. The role of oncogenic RAS and its associated genetic events in AML are not yet defined. We examined the frequency of RAS mutation in 239 Thai de novo adult AML patients using polymerase chain reaction-single-strand conformational polymorphism analysis. Thirty-five RAS mutations were found in 32 cases (13%) predominantly classified as M1/M2 (53%) followed by M4/M5 subtype (38%). Ten cases were positive for N-RAS codon 12, 11 cases for N-RAS codon 61, 13 cases for N-RAS codon 13, and one case for K-RAS codon 13. No mutation was found in K-RAS exon 2 or H-RAS. The most common base substitution was the G to A transition at codon 13. Most M1/M2 cases had mutations at codon 12 or 13, whereas M4/M5 cases preferentially affected codon 61. Half of the patients with RAS mutations had abnormal karyotypes with the majority involving chromosomes 21, 11 and 7. Four patients had core-binding factor leukemia and four additional patients had coexisting FLT3 or AML1 mutation. One patient had RAS, FLT3 and t(8;21) and the other had RAS, AML1 point mutation and del(9q). In conclusion, mutation of RAS gene was not as common in the Thais as in the western population. Several additional genetic abnormalities occurred in RAS-mutated patients. Future molecular-targeting approaches should take into account the multiple genetic events that coexist with RAS mutations in AML patients.

    European journal of haematology 2006;77;1;51-6

  • Genetic and epigenetic alterations in lung tumors from bitransgenic Ki-rasG12C expressing mice.

    Floyd HS, Jennings-Gee JE, Kock ND and Miller MS

    Department of Cancer Biology, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.

    Mutations in Ki-ras occur in approximately 30-50% of patients with adenocarcinoma (AC) of the lung. We previously reported the development of a bitransgenic mouse model that expressed the human Ki-ras(G12C) allele in a lung-specific, tetracycline-inducible manner and gave rise to benign lung tumors. In the current study, these benign tumors, which represent relatively early lesions in neoplastic progression, were analyzed for molecular alterations secondary to mutant Ki-ras expression to determine the gene(s) that contribute to adenoma (AD) development. Tumors were removed following doxycycline (DOX) treatment for 9 and 12 mo and examined for alterations in cell-cycle regulatory genes. Quantification of mRNA expression for cyclin D1, retinoblastoma, p16(Ink4a), p19(Arf), and survivin was carried out by real-time PCR. All of the tumors examined exhibited a mean reduction of approximately fivefold for the retinoblastoma gene (P < 0.02). Increased expression of both p19(Arf) and survivin were detected in a majority of the tumors examined (P < 0.01 and 0.001, respectively), but no change in cyclin D1 RNA expression was observed. A subset of the lung tumors (8/28) displayed reduced levels of p16(Ink4a) expression (P = 0.02). Immunohistochemical analysis confirmed the upregulation of p19(Arf) and survivin in all 10 of the lung tumors examined. However, increased staining for cyclin D1 was observed in the tumor tissue. In addition, increased levels of activated p53 were found in lung tumor tissues stained with an anti-phospho-p53 antibody, while an absence of staining was observed with an anti-phospho-pRb antibody in both normal control and tumor tissue. Analysis of the methylation status of p16(Ink4a) by methylation-specific PCR (MSP) demonstrated that seven of eight tumors exhibiting decreased expression of p16(Ink4a) had at least partial methylation of the promoter region. Single stranded conformational polymorphism (SSCP) analysis demonstrated that neither exons 1 or 2 of p16(Ink4a) nor exons 5-8 of p53 exhibited mutations. These data thus identify alterations in specific genes and pathways that combine with the mutation in Ki-ras to promote the formation of benign lung tumors and suggest potential targets for the development of novel chemotherapeutic and chemopreventive agents during the early stages of lung tumor progression.

    Funded by: NCI NIH HHS: R01 CA91909

    Molecular carcinogenesis 2006;45;7;506-17

  • Germline missense mutations affecting KRAS Isoform B are associated with a severe Noonan syndrome phenotype.

    Carta C, Pantaleoni F, Bocchinfuso G, Stella L, Vasta I, Sarkozy A, Digilio C, Palleschi A, Pizzuti A, Grammatico P, Zampino G, Dallapiccola B, Gelb BD and Tartaglia M

    Dipartimento di Biologia Cellulare e Neuroscienze, Istituto Superiore di Sanita, Rome, Italy.

    Noonan syndrome (NS) is a developmental disorder characterized by short stature, facial dysmorphia, congenital heart disease, and multiple skeletal and hematologic defects. NS is an autosomal dominant trait and is genetically heterogeneous. Gain of function of SHP-2, a protein tyrosine phosphatase that positively modulates RAS signaling, is observed in nearly 50% of affected individuals. Here, we report the identification of heterozygous KRAS gene mutations in two subjects exhibiting a severe NS phenotype with features overlapping those of cardiofaciocutaneous and Costello syndromes. Both mutations were de novo and affected exon 6, which encodes the C-terminal portion of KRAS isoform B but does not contribute to KRAS isoform A. Structural analysis indicated that both substitutions (Val152Gly and Asp153Val) perturb the conformation of the guanine ring-binding pocket of the protein, predicting an increase in the guanine diphosphate/guanine triphosphate (GTP) dissociation rate that would favor GTP binding to the KRASB isoform and bypass the requirement for a guanine nucleotide exchange factor.

    Funded by: Telethon: GGP04172

    American journal of human genetics 2006;79;1;129-35

  • Low somatic K-ras mutation frequency in colorectal cancer diagnosed under the age of 45 years.

    Alsop K, Mead L, Smith LD, Royce SG, Tesoriero AA, Young JP, Haydon A, Grubb G, Giles GG, Jenkins MA, Hopper JL and Southey MC

    Genetic Epidemiology Laboratory, Department of Pathology, University of Melbourne, Vic., Australia.

    Somatic mutation of K-ras is known to be a common event in colorectal cancer tumourigenesis however its association with age at onset has not been widely explored. In this study, we have analyzed tumours from a population-based study of colorectal cancer diagnosed before the age of 45 years, in which cases had been previously screened for germ-line mismatch repair gene mutations and for microsatellite instability. We used a micro-dissection and sequencing approach to search for somatic K-ras mutations in codons 12, 13 and 61 in 101 early-onset colorectal cancers. Six (6%) somatic K-ras mutations were detected; five in codon 12 (4 G>T transitions and 1 G>A) and one in codon 13 (G>A transition). All codon 12 mutations were identified in microsatellite stable tumours and the codon 13 mutation was identified in a MSI-high tumour. Four cases with K-ras mutations had no reported family history of colorectal cancer and two had some family history of colorectal cancer. None were known to carry a germ-line mutation in hMSH2, hMLH1, hMSH6 or hPMS2. The role of somatic K-ras mutations in early-onset colorectal cancer carcinogenesis appears to be minor, in contrast to its significant role in colorectal cancer of later age of onset.

    European journal of cancer (Oxford, England : 1990) 2006;42;10;1357-61

  • Frequent involvement of ras-signalling pathways in both polypoid-type and flat-type early-stage colorectal cancers.

    Noda H, Kato Y, Yoshikawa H, Arai M, Togashi K, Nagai H, Konishi F and Miki Y

    Department of Molecular Diagnosis, Japanese Foundation for Cancer Research, Tokyo, Japan.

    The development of colorectal neoplasms proceeds mainly via the adenoma-carcinoma sequence. BRAF and RASSF1A are members of Ras-signaling pathways, but the roles of their aberrations in colorectal carcinogenesis remain unclear. The authors studied mutations of the BRAF and K-ras genes, RASSF1A promoter methylation, and p53 overexpression in 43 polypoid-type and 30 flat-type early-stage colorectal cancers. No tumor simultaneously showed any combination of K-ras mutations, BRAF mutations, and RASSF1A promoter methylation. Three of the 73 tumors (4.1%) had BRAF mutations. All BRAF mutation-positive tumors were flat-type cancers, not associated with coexisting adenoma or p53 overexpression. RASSF1A promoter methylation was detected in 12 out of 73 tumors (16.4%), and the proportion of positive cases was similar in polypoid-type and flat-type cancers. BRAF mutations, K-ras mutations, and RASSF1A promoter methylation independently participate in early-stage colorectal carcinogenesis. BRAF mutations are involved only in flat-type cancers, whereas RASSF1A promoter methylation is involved in both polypoid-type and flat-type cancers. Thus, BRAF mutations most likely participate in de novo colorectal carcinogenesis, K-ras mutations in the adenoma-carcinoma sequence of colorectal carcinogenesis, and RASSF1A promoter methylation in both cascades.

    Journal of experimental & clinical cancer research : CR 2006;25;2;235-42

  • Molecular detection of TP53, Ki-Ras and p16INK4A promoter methylation in plasma of patients with colorectal cancer and its association with prognosis. Results of a 3-year GOIM (Gruppo Oncologico dell'Italia Meridionale) prospective study.

    Bazan V, Bruno L, Augello C, Agnese V, Calò V, Corsale S, Gargano G, Terrasi M, Schirò V, Di Fede G, Adamo V, Intrivici C, Crosta A, Rinaldi G, Latteri F, Dardanoni G, Grassi N, Valerio MR, Colucci G, Macaluso M, Russo A and Gruppo Oncologico dell'Italia Meridionale

    Section of Medical Oncology and Section of Surgical Oncology, Department of Surgical and Oncology, Università di Palermo, Italy.

    Background: Despite the improvement in detection and surgical therapy in the last years, the outcome of patients affected by colorectal carcinoma (CRC) remains limited by metastatic relapse. The aim of this study was to investigate the presence of free tumor DNA in the plasma of CRC patients in order to understand its possible prognostic role.

    Ki-Ras, TP53 mutations and p16(INK4A) methylation status were prospectively evaluated in tumor tissues and plasma of 66 CRC patients.

    Results: In 50 of the 66 primitive tumor cases (76%) at least one significant alteration was identified in Ki-Ras and/or TP53 and/or p16(INK4A) genes. Eighteen of the 50 patients presented the same alteration both in the plasma and in the tumor tissue. At univariate analysis, Ki-Ras mutations proved to be significantly related to quicker relapse (P <0.01), whereas only a trend towards statistical significance (P = 0.083) was observed for the TP53 mutations

    Conclusions: Detection of Ki-Ras and TP53 mutation in plasma should be significantly related to disease recurrence. These data suggest that patients with a high risk of recurrence can be identified by means of the analysis of tumor-derived plasma DNA with the use of fairly non-invasive techniques.

    Annals of oncology : official journal of the European Society for Medical Oncology / ESMO 2006;17 Suppl 7;vii84-90

  • Follicular carcinoma presenting as autonomous functioning thyroid nodule and containing an activating mutation of the TSH receptor (T620I) and a mutation of the Ki-RAS (G12C) genes.

    Niepomniszcze H, Suárez H, Pitoia F, Pignatta A, Danilowicz K, Manavela M, Elsner B and Bruno OD

    Division of Endocrinology, Hospital de Clínicas, University of Buenos Aires, Buenos Aires, Argentina. hniepom@elsitio.net

    Most autonomous functioning thyroid nodules (AFTN) are benign thyroid follicular neoplasms. There are rare reports of malignant hot nodules, in which activating mutations of the TSH receptor (TSHR) were found. We report a case of follicular carcinoma presenting as an AFTN causing subclinical hyperthyroidism in a 64-year-old woman who had a 6-cm hot nodule in the left thyroid lobe. Genomic DNA was extracted from paraffin-embedded tissues from the tumor and extratumoral thyroid tissue. Sequence analyses revealed point mutations in two different genes: the normal ACC sequence at codon 620 of the TSHR gene was replaced by ATC, changing the threonine by isoleucine (T620I); and the wild-type GGT at codon 12 of Ki-RAS mutated to TGT, replacing glycine by cysteine (G12C). In transfection experiments the T620I mutant showed constitutive activity in terms of cyclic adenosine monophosphate (cAMP) production when permanently transfected in 3T3 cells. Here, we describe for the first time an activating mutation in 3codon 620 of the TSHR. In addition, the cancerous AFTN also contained a G12C Ki-RAS mutation. We hypothesize that the combination of these two mutations might have played an important role in both the hyperfunction of the tumor and the carcinogenetic process.

    Thyroid : official journal of the American Thyroid Association 2006;16;5;497-503

  • KRAS mutation status is predictive of response to cetuximab therapy in colorectal cancer.

    Lièvre A, Bachet JB, Le Corre D, Boige V, Landi B, Emile JF, Côté JF, Tomasic G, Penna C, Ducreux M, Rougier P, Penault-Llorca F and Laurent-Puig P

    Université Paris-Descartes, Institut National de la Sante et de la Recherche Medicale UMR-775, Paris, France.

    The anti-epidermal growth factor receptor (anti-EGFR) cetuximab has been proven to be efficient in metastatic colorectal cancer. The molecular mechanisms underlying the clinical response to this drug remain unknown. Genetic alterations of the intracellular effectors involved in EGFR-related signaling pathways may have an effect on response to this targeted therapy. In this study, tumors from 30 metastatic colorectal cancer patients treated by cetuximab were screened for KRAS, BRAF, and PIK3CA mutation by direct sequencing and for EGFR copy number by chromogenic in situ hybridization. Eleven of the 30 patients (37%) responded to cetuximab. A KRAS mutation was found in 13 tumors (43%) and was significantly associated with the absence of response to cetuximab (KRAS mutation in 0% of the 11 responder patients versus 68.4% of the 19 nonresponder patients; P = 0.0003). The overall survival of patients without KRAS mutation in their tumor was significantly higher compared with those patients with a mutated tumor (P = 0.016; median, 16.3 versus 6.9 months). An increased EGFR copy number was found in 3 patients (10%) and was significantly associated with an objective tumor response to cetuximab (P = 0.04). In conclusion, in this study, KRAS mutations are a predictor of resistance to cetuximab therapy and are associated with a worse prognosis. The EGFR amplification, which is not as frequent as initially reported, is also associated with response to this treatment.

    Cancer research 2006;66;8;3992-5

  • Distributions of five common point mutants in the human tracheal-bronchial epithelium.

    Sudo H, Li-Sucholeiki XC, Marcelino LA, Gruhl AN, Zarbl H, Willey JC and Thilly WG

    Massachusetts Institute of Technology, 77 Massachusetts Ave., Bldg. 16-743 Cambridge, MA 02139, USA.

    The mutations C742T, G746T, G747T in the TP53 gene and G35T in the KRAS gene have been repeatedly found in sectors of human tumors by direct DNA sequencing. The mutation G508A in the HPRT1 gene has been repeatedly found among peripheral T lymphocytes by clonal expansion under selective conditions. To discover if these mutations also occur frequently in normal tissues from which tumors arise, we have developed and validated allele-specific mismatch amplification mutation assays (MAMA) for each mutation. Reconstruction experiments demonstrated linearity in the range of 9-3000 mutant alleles among 3 x 10(6) wild-type alleles. The cumulative distributions of all negative controls established robust detection limits (P<0.05) of 34-125 mutants per 10(6) copies assayed depending on the mutation. One hundred and seventy-seven micro-anatomical samples of approximately (0.5-6)x10(6) tracheal-bronchial epithelial cells from nine non-smokers were assayed representing en toto the equivalent of approximately 1.6 human bronchial trees to the fifth bifurcation. Statistically significant mutant copy numbers were found in 257 of 463 assays. Clusters of mutant copies ranged from 10 to 1000 in 239/257 positive samples. As all five point mutations were detected at mutant fractions of >10(-5) in two or more lungs, we infer that they are mutational hotspots generated in lung epithelial stem cells. As the cancer-associated mutations did not differ in cluster size distribution from the HPRT1 mutation, we infer that none of the mutations conferred a growth advantage to somatic heterozygous clusters or maintenance turnover units. Specific mutants appeared in very large copy numbers, 1000-35,000, in 18/257 positive assays. Various hypotheses to account for the observed cluster size distributions are offered.

    Mutation research 2006;596;1-2;113-27

  • Alcohol and the risk of colon and rectal cancer with mutations in the K-ras gene.

    Bongaerts BW, de Goeij AF, van den Brandt PA and Weijenberg MP

    Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Department of Epidemiology, University Maastricht, 6200 MD Maastricht, The Netherlands. Brenda.Bongaerts@epid.unimaas.nl

    The first metabolite of alcohol, acetaldehyde, may trigger replication errors and mutations in DNA, which may predispose to developing colorectal cancer (CRC). In a prospective study on colon and rectal cancer, we investigated the following hypotheses: alcohol consumption is associated with an increased risk of mutations in the K-ras oncogene, and beer consumption is associated with an increased risk of G-->A mutations in this gene. Therefore, we studied the associations between consumption of alcohol and alcoholic beverages and the risk of CRC without and with specific K-ras gene mutations. In 1986, 120,852 men and women, aged 55-69 years, completed a questionnaire on risk factors for cancer. The case-cohort approach was used for data processing and analyses. After 7.3 years of follow-up, excluding the first 2.3 years, complete data from 4,076 subcohort members, 428 colon and 150 rectal cancer patients, were available for data analyses. Incidence rate ratios (RRs) and corresponding 95% confidence intervals (95% CIs) were estimated using Cox proportional hazards models. Compared to abstaining, a total alcohol consumption of 30.0 g/day and more was associated with the risk of colon and rectal cancer with and without a K-ras mutation in both men and women. Independent from alcohol intake, liquor consumption when compared to nonliquor consumption was associated with an increased risk of rectal cancer with a wild type K-ras in men (RR: 2.25, 95% CI: 1.0-5.0). Beer consumption was not clearly associated with the risk of colon and rectal tumors harboring G-->A mutations in the K-ras gene in men. This association could not be assessed in women because of sparse beer consumption. In conclusion, alcohol does not seem to be involved in predisposing to CRC through mutations in the K-ras gene, and specifically beer consumption is not associated with colon and rectal tumors harboring a G-->A mutation.

    Alcohol (Fayetteville, N.Y.) 2006;38;3;147-54

  • Polymorphisms in insulin-related genes predispose to specific KRAS2 and TP53 mutations in colon cancer.

    Samowitz WS, Wolff RK, Ma KN, Andersen K, Caan B and Slattery ML

    Department of Pathology, University of Utah, Salt Lake City, UT 84108, USA.

    Risk factors for colon cancer may not only influence the overall risk of cancer but also the risk for specific types of mutations. We evaluated the effect of polymorphisms in four insulin-related genes (G972R in IRS1, G1057D in IRS2, a CA repeat in IGFI and an A/C polymorphism at -202 of IGFBP3) on the risk of microsatellite instability and KRAS2 and TP53 mutations in a population-based set of 1788 cases of colon cancer and 1981 controls. The GR/RR IRS1 genotypes were associated with an increased risk of colon cancers with the KRAS2 G12D mutation (OR 2.3, 95% CI 1.5, 3.5 versus controls, OR 1.7, 95% CI 1.1, 2.6 versus KRAS2 wild type), the "no 192" IGFI genotype increased the risk of the KRAS2 G13D mutation (OR 2.3, 95% CI 1.2, 4.2 versus controls, OR 2.1, 95% CI 1.1, 4.0 versus wild type), and the DD IRS2 genotype increased the risk of the G12V KRAS2 mutation (OR 1.8, 95% CI 0.9, 3.5 versus controls, OR 2.0, 95% CI 1.0, 4.0 versus wild type). Polymorphisms in IRS1 and IGF1 were also associated with an approximately two-fold increased risk of specific TP53 mutations relative to controls without cancer. We conclude that polymorphisms in some insulin-related genes are associated with an increased risk of colon cancer with specific KRAS2 and TP53 mutations, implying a link between these genetic changes and specific mutational pathways in carcinogenesis.

    Funded by: NCI NIH HHS: CA48998, CA85846, N01-PC-67000, R01 CA048998, R01 CA048998-10, R01 CA061757, R01 CA061757-10, R01 CA085846, R01 CA085846-06

    Mutation research 2006;595;1-2;117-24

  • Distinct epidermal growth factor receptor and KRAS mutation patterns in non-small cell lung cancer patients with different tobacco exposure and clinicopathologic features.

    Tam IY, Chung LP, Suen WS, Wang E, Wong MC, Ho KK, Lam WK, Chiu SW, Girard L, Minna JD, Gazdar AF and Wong MP

    Department of Pathology, Dental Public Health, Medicine, University of Hong Kong.

    Purpose: This study evaluated the mutational profile of epidermal growth factor receptor (EGFR) and KRAS in non-small cell lung cancers in Hong Kong and determined their relation with smoking history and other clinicopathologic features.

    Mutational profile of exons 18 to 21 of EGFR and codons 12, 13, and 61 of KRAS were determined in 215 adenocarcinomas, 15 squamous cell (SCC), and 11 EBV-associated lymphoepithelioma-like carcinomas (LELC).

    Results: EGFR mutations were prevalent in adenocarcinomas (115 of 215), uncommon in LELC (1 of 11), and not found in SCC (P < 0.001). Among adenocarcinomas, mutations were associated with nonsmokers (83 of 111; P < 0.001), female gender (87 of 131; P < 0.001), and well-differentiated (55 of 86) compared with poorly differentiated (11 of 41) tumors (P < 0.001). Decreasing mutation rates with increasing direct tobacco exposure was observed, with 74.8% (83 of 111) in nonsmokers, 61.1% (11 of 18) in passive, 35.7% (10 of 28) in previous, and 19.0% (11 of 58) in current smokers. There were 53% amino acid substitutions, 43% in-frame deletions, and 4% insertions. Complex patterns with 13% double mutations, including five novel substitutions, were observed. For KRAS, mutations occurred in adenocarcinoma only (21 of 215) and were associated with smokers (11 of 58; P = 0.003), men (14 of 84; P = 0.009) and poorly differentiated (7 of 41) compared with well-differentiated (4 of 86) tumors (P = 0.037). EGFR and KRAS mutations occurred in mutually exclusive tumors. Regression analysis showed smoking history was the significant determinant for both mutations, whereas gender was a confounding factor.

    Conclusion: This study shows EGFR mutations are prevalent in lung adenocarcinoma and suggests that it plays an increasing oncogenic role with decreasing direct tobacco damage.

    Funded by: NCI NIH HHS: P50CA70907

    Clinical cancer research : an official journal of the American Association for Cancer Research 2006;12;5;1647-53

  • K-ras mutations in incident sporadic colorectal adenomas.

    Barry EL, Baron JA, Grau MV, Wallace K and Haile RW

    Department of Community and Family Medicine, Dartmouth Medical School, Lebanon, New Hampshire 03766, USA. elizabeth.l.barry@dartmouth.edu

    Background: Although K-ras is the most frequently mutated protooncogene in colorectal carcinoma, the specific role and timing of K-ras mutations in colorectal carcinogenesis remains controversial. In the current study, the authors investigated associations with K-ras mutation in incident sporadic colorectal adenomas that occurred during a chemoprevention trial of calcium supplementation.

    Methods: K-ras genotyping was performed on 303 colorectal adenomas that were removed from 207 participants during the follow-up phase of the Calcium Polyp Prevention Study. Mutations in codons 12 or 13 of K-ras were detected by denaturing high-performance liquid chromatography and were confirmed by direct sequencing.

    Results: The adenomas analyzed had a mean estimated size of 0.5 cm, and 3.0% were identified with mutations (95% confidence interval [95% CI], 1.3-4.4%). These mutations were more common in larger adenomas (risk ratio [RR], 12.7 for tumors that measured > 0.5 cm vs. < or = 0.5 cm; 95% CI, 2.7-59.7), in adenomas with more advanced histology (RR, 20.6 for tubulovillous/villous vs. tubular; 95% CI, 4.4-96.0), and in adenomas that were located in the rectum compared with the colon (RR, 8.4; 95% CI, 2.3-30.5).

    Conclusions: Compared with previous studies, the current analysis was novel, because it focused on incident adenomas that were diagnosed within a few years of a previous "clean" colonoscopy. The results provided evidence for a very low rate of K-ras mutation among these small, early adenomas and strong support for a role of K-ras mutations in adenoma progression.

    Funded by: NCI NIH HHS: CA-046927, U01 CA046927

    Cancer 2006;106;5;1036-40

  • Germline KRAS and BRAF mutations in cardio-facio-cutaneous syndrome.

    Niihori T, Aoki Y, Narumi Y, Neri G, Cavé H, Verloes A, Okamoto N, Hennekam RC, Gillessen-Kaesbach G, Wieczorek D, Kavamura MI, Kurosawa K, Ohashi H, Wilson L, Heron D, Bonneau D, Corona G, Kaname T, Naritomi K, Baumann C, Matsumoto N, Kato K, Kure S and Matsubara Y

    Department of Medical Genetics, Tohoku University School of Medicine, Sendai, Japan.

    Cardio-facio-cutaneous (CFC) syndrome is characterized by a distinctive facial appearance, heart defects and mental retardation. It phenotypically overlaps with Noonan and Costello syndrome, which are caused by mutations in PTPN11 and HRAS, respectively. In 43 individuals with CFC, we identified two heterozygous KRAS mutations in three individuals and eight BRAF mutations in 16 individuals, suggesting that dysregulation of the RAS-RAF-ERK pathway is a common molecular basis for the three related disorders.

    Nature genetics 2006;38;3;294-6

  • Germline KRAS mutations cause Noonan syndrome.

    Schubbert S, Zenker M, Rowe SL, Böll S, Klein C, Bollag G, van der Burgt I, Musante L, Kalscheuer V, Wehner LE, Nguyen H, West B, Zhang KY, Sistermans E, Rauch A, Niemeyer CM, Shannon K and Kratz CP

    Department of Pediatrics, University of California, 513 Parnassus Avenue, San Francisco, California 94143, USA.

    Noonan syndrome (MIM 163950) is characterized by short stature, facial dysmorphism and cardiac defects. Heterozygous mutations in PTPN11, which encodes SHP-2, cause approximately 50% of cases of Noonan syndrome. The SHP-2 phosphatase relays signals from activated receptor complexes to downstream effectors, including Ras. We discovered de novo germline KRAS mutations that introduce V14I, T58I or D153V amino acid substitutions in five individuals with Noonan syndrome and a P34R alteration in a individual with cardio-facio-cutaneous syndrome (MIM 115150), which has overlapping features with Noonan syndrome. Recombinant V14I and T58I K-Ras proteins show defective intrinsic GTP hydrolysis and impaired responsiveness to GTPase activating proteins, render primary hematopoietic progenitors hypersensitive to growth factors and deregulate signal transduction in a cell lineage-specific manner. These studies establish germline KRAS mutations as a cause of human disease and infer that the constellation of developmental abnormalities seen in Noonan syndrome spectrum is, in large part, due to hyperactive Ras.

    Funded by: NCI NIH HHS: R01 CA104282, R01 CA72614

    Nature genetics 2006;38;3;331-6

  • Low correspondence between K-ras mutations in pancreatic cancer tissue and detection of K-ras mutations in circulating DNA.

    Marchese R, Muleti A, Pasqualetti P, Bucci B, Stigliano A, Brunetti E, De Angelis M, Mazzoni G, Tocchi A and Brozzetti S

    FBF S. Pietro Hospital AFaR Research Centre, University of Rome La Sapienza, Rome, Italy. marchese.rodolfo@fbfrm.it

    Objective: K-ras is the most frequently mutated gene in pancreatic cancer; reported rates range from 70% to 90%. The aim of this study was to evaluate the correspondence between K-ras mutations in pancreatic cancer tissue and in circulating DNA and the value of K-ras mutations as serological marker.

    Methods: The research was conducted in 30 patients with pancreatic cancer in whom both plasma and neoplastic tissues were available. Such research was extended to circulating DNA isolated from 40 patients with chronic pancreatitis. Mutations in codon 12 were examined by mutant allele-specific amplification method and by direct sequencing. Serum values of routinely used tumor markers such as carbohydrate antigen (Ca) 19.9, carcinoembryonic antigen, Ca 50, and Ca 242 have been tested in all the patients enrolled in this study.

    Results: K-ras mutations were detected in 70% of neoplastic tissue samples, but no mutated DNA resulted in circulating DNA samples. The 60% of patients with tissue K-ras mutation showed elevation of some tumor markers among Ca 19.9, carcinoembryonic antigen, Ca 50, and Ca 242. As a whole, these last showed low sensitivity (20%-56.67%) and specificity (56.67%-77.5%) when compared with chronic pancreatitis.

    Conclusion: Over the years, there has been no change in the direction of an earlier diagnosis by serological markers, and also, these data indicate that K-ras mutation in serum is an unsatisfactory method for the detection in patients with pancreatic cancer as well as in patients with high risk of progression toward neoplastic pancreatic disease.

    Pancreas 2006;32;2;171-7

  • Mutational analysis of K-ras and Ras protein expression in larynx squamous cell carcinoma.

    Ruíz-Godoy R LM, Garcia-Cuellar CM, Herrera González NE, Suchil BL, Pérez-Cárdenas E, Sácnchez-Pérez Y, Suárez-Roa ML and Meneses A

    Basic Research Subdirection, National Institute of Cancerology, Tlalpan, Mexico.

    The ras gene family (H, K and N-ras) encodes the Ras protein, a GTPase-activating protein that regulates several signal transduction pathways including cellular proliferation and differentiation. Mutations in codons 12, 13 and 61 of the ras genes constitute one of the most frequent alterations in human cancer. In the Western Hemisphere, a low frequency of mutations in these genes has been observed in head and neck carcinomas; a higher frequency has been found in countries such as India and Taiwan. Increased protein expression is a relatively frequent event in larynx carcinomas. This study was aimed to evaluate the participation of the k-ras gene and Ras expression in 20 Mexican patients with larynx squamous carcinoma, 2 with dysplasia and 4 with normal mucosa. Samples (of 26 patients) were embedded in paraffin and immunohistochemical analysis was performed for the Ras protein, as well as amplification of the k-ras gene exon 1 (108 bp) by laser capture microdissection. Then, DNA extraction, PCR and sequencing were performed looking for possible mutation in codons 12 and 13. All patients with larynx carcinoma were men, median age 62 years. Eighty-five percent of the patients had risk factors such as smoking and/or alcohol consumption, 25% were in clinical stages I and II, and 75% in stages III and IV; 45% of the patients presented tumor recurrence or persistence. In this study, no mutations were found in codons 12 or 13 of the k-ras gene; however, protein expression was observed in 95% of the samples and a higher expression of the protein was associated with tumor recurrence or persistence, although this was not statistically significant. Unexpectedly, well-differentiated carcinomas and dysplasias presented an increase in protein expression. These results suggest that ras may be involved in early stages of larynx carcinogenesis and may be activated by other mechanisms different from mutations, such as epigenetic events.

    Journal of experimental & clinical cancer research : CR 2006;25;1;73-8

  • Loss of heterozygosity of Kras2 gene on 12p12-13 in Chinese colon carcinoma patients.

    Wan J, Li H, Li Y, Zhu ML and Zhao P

    Department of Grastroenterology, General Hospital of the Chinese PLA, Beijing, China.

    Aim: To study the loss of heterozygosity (LOH) on 12p12-13 in Chinese colon carcinoma patients.

    Methods: DNA was extracted from 10 specimens of cancer tissue, 10 specimens of adjacent tissue and 10 specimens of normal tissue, respectively. LOH of Kras2 gene was analyzed by polymerase chain reaction (PCR) and denaturing polyacrylamide gel electrophoresis using 11 microsatellite markers on 12p-12-13.

    Results: LOH of Kras gene was detected at least on one marker of 12p-12-13 in 30% (3/10) of adjacent tissue specimens. The highest frequency of LOH was identified on D12S1034 in 28.57% (2/7) of adjacent tissue specimens. LOH was detected at least on one marker of 12p12-13 in 60% (6/10) of carcinoma tissue specimens, the most frequent LOH was found on D12S1034 and D12S1591 in 42.86% (3/7) of carcinoma tissue specimens. LOH was detected in 30% (3/10) of carcinoma tissue specimens, 30% (3/10) of adjacent tissue specimens, and no signal in 1% (1/0) carcinoma tissue specimen. The occurrence of LOH did not correlate with sex, age, tumor size and lymph node metastasis.

    Conclusion: Genomic instability may occur on 12p-12-13 of Kras2 gene in the development and progression of colon carcinoma. The high LOH of Kras2 gene may directly influence the transcription and translation of wild type Kras2 gene.

    World journal of gastroenterology 2006;12;7;1033-7

  • Transcriptional targets of hepatocyte growth factor signaling and Ki-ras oncogene activation in colorectal cancer.

    Seiden-Long IM, Brown KR, Shih W, Wigle DA, Radulovich N, Jurisica I and Tsao MS

    Ontario Cancer Institute/Princess Margaret Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada.

    Both Ki-ras mutation and hepatocyte growth factor (HGF) receptor Met overexpression occur at high frequency in colon cancer. This study investigates the transcriptional changes induced by Ki-ras oncogene and HGF/Met signaling activation in colon cancer cell lines in vitro and in vivo. The model system used in these studies included the DLD-1 colon cancer cell line with a mutated Ki-ras allele, and the DKO-4 cell line generated from DLD-1, with its mutant Ki-ras allele inactivated by targeted disruption. These cell lines were transduced with cDNAs of full-length Met receptor. Microarray transcriptional profiling was conducted on cell lines stimulated with HGF, as well as on tumor xenograft tissues. Overlapping genes between in vitro and in vivo microarray data sets were selected as a subset of HGF/Met and Ki-ras oncogene-regulated targets. Using the Online Predicted Human Interaction Database, novel HGF/Met and Ki-ras regulated proteins with putative functional linkage were identified. Novel proteins identified included histone acetyltransferase 1, phosphoribosyl pyrophosphate synthetase 2, chaperonin containing TCP1, subunit 8, CSE1 chromosome segregation 1-like (yeast)/cellular apoptosis susceptibility (mammals), CCR4-NOT transcription complex, subunit 8, and cyclin H. Transcript levels for these Met-signaling targets were correlated with Met expression levels, and were significantly elevated in both primary and metastatic human colorectal cancer samples compared to normal colorectal mucosa. These genes represent novel Met and/or Ki-ras transcriptionally coregulated genes with a high degree of validation in human colorectal cancers.

    Oncogene 2006;25;1;91-102

  • Somatic mutations of ERBB2 kinase domain in gastric, colorectal, and breast carcinomas.

    Lee JW, Soung YH, Seo SH, Kim SY, Park CH, Wang YP, Park K, Nam SW, Park WS, Kim SH, Lee JY, Yoo NJ and Lee SH

    Department of Pathology, College of Medicine, The Catholic University of Korea, Seoul, Korea.

    Purpose: Recent reports revealed that the kinase domain of the ERBB2 gene is somatically mutated in lung adenocarcinoma, suggesting the mutated ERBB2 gene as an oncogene in human cancers. However, because previous reports focused the mutational search of ERBB2 primarily on lung cancers, the data on ERBB2 mutations in other types of human cancers have been largely unknown.

    Here, we did a mutational analysis of the ERBB2 kinase domain by PCR single-strand conformational polymorphism assay in gastric, colorectal, and breast carcinoma tissues.

    Results: We detected the ERBB2 kinase domain mutations in 9 of 180 gastric carcinomas (5.0%), in 3 of 104 colorectal carcinomas (2.9%), and in 4 of 94 breast carcinomas (4.3%). All of the detected ERBB2 mutations except for one in-frame deletion mutation were missense mutations. Of the 16 ERBB2 mutations detected, 4 affected Val777 in the exon 20 site, and 3 affected Leu755 in the exon 19 site. We simultaneously analyzed the somatic mutations of EGFR, K-RAS, PIK3CA, and BRAF genes in the 16 samples with ERBB2 mutations, and found that all of the 3 colorectal carcinoma samples with ERBB2 mutations harbored K-RAS mutations.

    Conclusion: This study showed that in addition to lung adenocarcinomas, ERBB2 kinase domain mutation occurs in other common human cancers such as gastric, breast, and colorectal cancers, and suggested that alterations of ERBB2-mediated signaling pathway by ERBB2 mutations alone or together with K-RAS mutations may contribute to the development of human cancers.

    Clinical cancer research : an official journal of the American Association for Cancer Research 2006;12;1;57-61

  • The association between selected risk factors for pancreatic cancer and the expression of p53 and K-ras codon 12 mutations.

    Fryzek JP, Garabrant DH, Schenk M, Kinnard M, Greenson JK and Sarkar FH

    Department of Environmental Health Sciences, University of Michigan School of Public Health, 109 Observatory Street, Ann Arbor, MI 48109-2029, USA.

    Background: Pancreatic cancer is a major contributor to cancer mortality. Studies suggest that a few risk factors, including cigarette smoking, body mass index, having a relative with pancreatic cancer, and diabetes may be related to pancreatic cancer risk.

    We conducted a case-control study in southeastern Michigan to examine the relation between the above mentioned risk factors and mutations of the K-ras oncogene and p53 tumor suppressor gene.

    Methods: Two hundred forty-five patients with newly diagnosed pancreatic cancer and 420 general population controls were enrolled in the study. For this analysis, all case subjects were restricted to the pancreatic cancer patients that had tissue blocks available for study (n = 51). In-person interviews were conducted to ascertain information on demographic and lifestyle factors. Adjusted logistic regression analyses were conducted to compare various subject characteristics of pancreatic cancer patients with K-ras and p53 mutations and their subtypes to the characteristics of the general population controls.

    Results: Smoking (adjusted odds ratio [aOR] = 2.0; 95% confidence interval [95%CI] = 0.9-4.3) and diabetes diagnosed 5 or more years before interview (aOR = 3.4; 95%CI = 1.3-8.8) were associated with pancreatic cancer patients positive for K-ras codon 12 mutations, but not with pancreatic cancer patients negative for K-ras codon 12 mutations. On the other hand, none of the examined risk factors were meaningfully related to patients with p53 mutations.

    Conclusions: This study suggests that some recognized risk factors for pancreatic cancer may also be associated with K-ras codon 12 mutations. However, further large-scale studies are warranted.

    Funded by: NCI NIH HHS: R25-CA57716; NIEHS NIH HHS: R01 ES07129

    International journal of gastrointestinal cancer 2006;37;4;139-45

  • Coexistence of K-ras mutations and HPV infection in colon cancer.

    Buyru N, Tezol A and Dalay N

    Department of Medical Biology, Cerrahpasa Medical Faculty, Istanbul University, Istanbul, Turkey. nbuyru@yahoo.com

    Background: Activation of the ras genes or association with human papillomavirus infection have been extensively studied in colorectal cancer. However, the correlation between K-ras mutations and HPV in colorectal cancer has not been investigated yet. In this study we aimed to investigate the presence of K-ras mutations and their correlation with HPV infection in colon cancer.

    Methods: K-ras mutations were analyzed by a mutagenic PCR assay and digestion with specific restriction enzymes to distinguish the wild-type and mutant codons. HPV infection was analyzed by PCR amplification and hybridization with specific probes by Southern blotting. Statistical analyses were performed by the chi-square and Fisher's exact tests

    Results: HPV gene fragments were detected in 43 tumors and 17 normal tissue samples. HPV 18 was the prevalent type in the tumor tissue. A mutation at codon 12 of the K-ras gene was present in 31 patients. 56% of the HPV-positive tumors also harbored a K-ras mutation. Codon 13 mutations were not observed. These data indicate that infection with high risk HPV types and mutational activation of the K-ras gene are frequent events in colorectal carcinogenesis.

    Conclusion: Our findings suggest that mutational activation of the K-ras gene is a common event in colon carcinogenesis and that HPV infection may represent an important factor in the development of the premalignant lesions leading to the neoplastic phenotype.

    BMC cancer 2006;6;115

  • Evaluation of the diagnostic value of serum tumor markers, and fecal k-ras and p53 gene mutations for pancreatic cancer.

    Wu X, Lu XH, Xu T, Qian JM, Zhao P, Guo XZ, Yang XO and Jiang WJ

    Department of Gastroenterology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.

    Objective: To evaluate the diagnostic value for pancreatic cancer of four serum tumor markers, carbohydrate antigen (CA) 199, CA242, CA50 and carcino-embryonic antigen (CEA), and fecal k-ras and p53 gene mutations.

    Methods: From February 2002 to March 2004, 136 patients were consecutively diagnosed with pancreatic cancer in the three participating medical centers. The diagnosis was confirmed by pathology in 53 patients, of whom five were excluded because they did not have measurement of serum tumor marker. The remaining 48 patients comprised the case group in the study. Ninety-six patients with benign digestive diseases diagnosed during the same period were recruited as control subjects. They were matched by sex and age. In both groups, serum CA199, CA242, CA50 and CEA were measured by ELISA, and fecal k-ras and p53 gene mutations were measured by PCR-restriction fragment length polymorphism and PCR-single strand conformational polymorphism, respectively. The receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to compare their diagnostic value, as well as the sensitivity, specificity and likelihood ratio. Moreover, independent and sensitive tests from these non-invasive approaches were selected to form a parallel test that may have further improved sensitivity for diagnosis of pancreatic cancer.

    Results: The AUC of serum CA199 and CA242 were 0.821 (95%CI 0.725-0.917) and 0.821 (95%CI 0.723-0.919), respectively. The optimal diagnostic value of serum CA199 for pancreatic cancer was 93 U/mL, with a sensitivity of 73.7% and specificity of 91.4%. The positive likelihood ratio of CA199 was 8.57, and the negative likelihood ratio was 0.29. The optimal diagnostic value of serum CA242 was 25 U/mL, with a sensitivity of 71.1% and specificity of 93.5%. The positive likelihood ratio of CA242 was 10.94, and the negative likelihood ratio was 0.31. The sensitivity of fecal k-ras gene mutation for diagnosis of panc