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Abstract: Aim: Mitogen-activated protein kinase (MAPK) cascade and phosphatidylinositol 3-kinase (PI3K) survival pathways are frequently activated in the progression of gastrointestinal malignancies. In this study, we aimed to determine the frequency of gene mutations in members of these pathways – Epithelial Growth Factor Receptor (EGFR), KRAS, BRAF, PIK3CA and MLK3 in a series of 63 gastric carcinomas with high levels of microsatellite instability (MSI). Methods: Gene mutation analysis was performed by PCR amplification followed by direct sequencing. In selected tumour cases, EGFR expression was evaluated by immunohistochemistry. Association studies between molecular data and clinicopathologic characteristics were performed. Results: Mutations in EGFR (3′-untranslated region [UTR] polyA repeat), KRAS, PIK3CA and MLK3 genes occurred in 30 (47.6%), 11 (17.5%), 9 (14.3%) and 2 (3.2%) of the MSI gastric cancer (GC) cases, respectively. No BRAF or EGFR hotspot mutations were identified. Overall, mutations in at least one of these genes were found in 55.6% (35/63) of gastric carcinomas. From those mutant cases 40.0% (14/35) of them had concomitant gene mutations, always involving EGFR polyA deletions. Interestingly, we observed significant associations between oncogenic mutations and female gender (p =0.046) old age of diagnosis (p =0.001) and intestinal subtype (p =0.043). Conclusion: Our results show that MSI gastric carcinoma frequently shows activation of EGFR-MAPK and PI3K pathways. Within all alterations found, deletions of the A13 repeats of EGFR were common, suggesting this molecular event as an important biomarker for stratification of GC patients for treatment with EGFR inhibitors. [Copyright &y& Elsevier]

Purpose: X-ray repair cross complementing group 1 (XRCC1) is one of the major DNA repair proteins involved in the bas-excision repair pathway. Several single-nucleotide polymorphisms in the XRCC1 gene are identified and related with increased cancer risk development. In particular, the -77T>C polymorphism located on the promoter region relates with lung cancer risk development. The aim of this study is to analyze the -77T>C allelic frequencies in a population composed of 456 primary gastric cancer patients (GC) and 507 blood donor controls.Methods: GC patients were observed at the University of Siena, Italy; clinicopathological data and family history were available for the cancer group. The control group is composed of blood donors. Constitutional genomic DNA was PCR amplified, and XRCC1 -77T>C was detected using restriction enzyme BsrB I and analyzed in a 3% agarose gel.Results: The -77C>C homozygous genotype was significantly associated with increased risk of gastric cardia carcinoma (p = 0.023) with an odds ratio of 1.65 (95% confidence interval 1.14 to 2.4). In the family history stratification, we report a significant association (p = 0.043) between the -77T>C polymorphism and GC cases with familial lung cancer aggregation.Conclusions: Our results suggest that the XRCC1 -77T>C polymorphism is a relevant host susceptibility factor for gastric cardia cancer development and specific subsets of familial clustering of GC. [ABSTRACT FROM AUTHOR]