Correlation between DNA methyltransferases expression and Epstein-Barr virus, JC polyomavirus and Helicobacter pylori infections in gastric carcinomas.

It' is accepted that aberrant expression of DNA methyltransferases (DNMTs) is responsible for hypermethylation in genes. However, there are limited data related to factors inducing aberrant expression of DNMTs. A total of 43 surgically resected gastrc carcinomas (GC) samples were analysed. Using immunohistochemistry assay we have determined expression level of DNMT1 and 3b. The presence of H.pylori was evaluated by histology, whereas JC polyomavirus (JCV) and Epstein-Barr virus (EBV) detection were carried out by PCR and in situ hybridization techniques, respectively. High expression of DNMT1 and 3b were detected in 46.5% and 53.5% of GC cases, respectively. Co-expression of DNMT1 and 3b were found in 37.2% of cases. Using different techniques, H. pylori, JCV and EBV were detected in 55.8%, 32.6% and 9%, respectively. Moreover, in 37% of cases, we noted the presence of JCV and/or EBV infections. H.pylori co-infection was found in 64.3% (9/14) of JCV positive cases and in 50% of EBV positive GC, without a reliable significant relationship. Correlation analyses have showed a marked increase in DNMT1 expression in EBV associated GC (P= 0.02). Also, co-expression of DNMT1 and 3b was significantly associated with EBV infection in GC (P=0.05). Similarly, JCV associated GC mostly displayed DNMT1 positive status, but the difference did not reach the significant threshold. Nevertheless, infection with JCV and/or EBV was significantly correlated with increased expression of DNMT1 in GC (P= 0.05). Our study suggests that EBV and JCV infections in GC correlated with deregulation of DNA methyltransferases.