Alterações genômicas quantitativas com potencial clínico no adenocarcinoma gástrico

Abstract

Gastric cancer is the fifth most frequent type of cancer and the third cause of cancer mortality worldwide. Despite progression in treatment of advanced gastric cancer, the prognosis of patients remains poor, in part due to the low rate of diagnosis during its early stages. This paradigm implies the necessity to search and identify molecular biomarkers for early gastric cancer diagnosis, as well as for disease monitoring, thus contributing to the development of new therapeutic approaches. Therefore, this study aimed at investigating copy number variations in gastric adenocarcnoma through array Comparative Genomic Hybridization (aCGH) technique and selecting genes for validation in a larger sample size by using real-time PCR, in order to find potential molecular biomarkers for this tumor type. The aCGH results demonstrated 22 gene alterations never described before as correlated with gastric carinogenesis, as well as several alterations significantly associated with serosal extravasation and patients aged less than or equal 50 years. Given that most of the genes had never been described in gastric cancer, we selected for validation four gene alterations that showed some consistency with studies published in the literature for other types of cancer. Thus, we investigated by real-time PCR the amplifications of RTEL1, B4GALT5, TRPV2 and ABCA13 genes. The results showed a high frequency of amplification of these genes, but the statistical associations with clinicopathological data of TRPV2 gene with younger patients and ABCA13, with serosal extravasation, observed by aCGH, were not confirmed. Moreover, new significant associations were demonstrated, including RTEL1 recurrent amplification associated with advanced age and intestinal type of gastric adenocarcinoma; B4GALT5 recurrent amplification associated with intestinal type of gastric adenocarcinoma; TRPV2 recurrent amplification associated with lymph node metastasis; ABCA13 recurrent amplification associated with lymph node metastasis and male patients and co-amplification of RTEL1 and ABCA13 associated with advanced staging. Therefore, the aCGH proved to be a useful tool for the investigating new genes associated with carcinogenesis. Additionally, recurrent amplification of RTEL1, B4GALT5, TRPV2 and ABCA13 seem to have an important role in the development and progression of gastric cancer and can be considered as potential biomarkers for this disease.