Relationship between HBV infection and DNMT expression in liver cancer tissues

Objective To investigate the expression of DNA methyltransferases (DNMTs) in cancerous tissues, paracancerous tissues, and cirrhotic tissues among patients with liver cancer and to analyze the relationship between HBV infection and DNMT expression.Methods Forty-four samples were divided into HBV infection group and non-HBV infection group according to whether at least one marker of HBV infection could be detected in blood or tissue.FQ-PCR was used to measure the mRNA expression levels of DNMTs in the cancerous tissues, paracancerous tissues, and cirrhotic tissues with different tumor stages and differentiations.The differences in DNMT expression between groups were determined by analysis of variance;the relationship between HBV infection and DNMT expression was evaluated by Spearman rank correlation analysis.Results Compared with the non-HBV infection group, the HBV infection group had significantly higher mRNA expression levels of DNMT1, 3A, and 3B in cancerous tissues (P=0.001, 0.006, and 0.02) and in cirrhotic tissues (P=0.007, 0.008, and 0.045) and significantly higher mRNA expression levels of DNMT1 and 3A in paracancerous tissues (P=0.01 and 0.04) .There were significant associations between HBV infection and DNMT expression (P=0.009 for DNMT1, 0.006 for DNMT3A, and 0.03 for DNMT3B) ;HBsAg, HBeAg, and HBV-DNA were closely related to DNMT1 expression (P=0.008, 0.032, and 0.006) .Conclusion The liver cancer patients with HBV infection have significantly higher mRNA expression levels of DNMT1, 3A, and 3B in cancerous and cirrhotic tissues than those without HBV infection.HBV infection may stimulate the expression of DNMTs, especially DNMT1, 3A, and 3B, thus promoting methylation of some tumor-suppressor genes.