Análise da expressão de DNA metiltransferases e methyl - binding proteins na carcinogênese gástrica

Abstract

Despite the worldwide decline in the incidence of gastric cancer in recent years, this type of cancer is the third with higher mortality. Modifications in the pattern of DNA methylation are common in different types of cancer, including gastric cancer. In addition, changes in the expression of proteins responsible for this epigenetic mechanism in tumors are associated with changes in DNA methylation patterns. Therefore, understanding the gene machinery of the DNA methylation during carcinogenesis is crucial for understanding the biological processes involved in tumor development. In the present study, the relative mRNA expression of the DNMT1, DNMT3A, DNMT3B, MeCP2 and MBD4 genes from 61 paired samples of gastric tumors and adjacent non-neoplastic gastric tissues and 30 gastric tissue samples from individuals without neoplasia. In the analysis between the different groups of samples, mRNA of DNMT1 gene was significantly more expressed in gastric tumor and non-neoplastic adjacent tissue when compared to gastric tissue of individual without neoplasia (p = 0.0196, p = 0.0466, respectively). In addition, we observed that DNMT3A mRNA was significantly more expressed in adjacent non-neoplastic gastric tissue compared to tumor tissue and non-neoplastic individuals (p = .0.0076, p = 0.0029, respectively). The analysis with clinicopathological data showed an association between DNMT3B mRNA expression with presence of lymph node metastasis (p = 0.034) and gastric tumor stage III-IV (p = 0.048). When performing the gene correlation, it was observed that MECP2 had a strong correlation between DNMT1 (0.666), DNMT3B (0.685) and MBD4 (0.790) genes, another correlation was found between DNMT3B and MBD4 (0.650). These results suggest that alterations in DNMT1 and DNMT3A gene mRNA expression may be present in the early stages of gastric carcinogenesis, DNMT3B can be used as a marker of prognosis.