Downregulation Of MiR-101by The Hepatitis B Virus X Protein And Induce Aberrant DNA Methylation By Targeting DNA Methyltransferase3A Contributes To Hepatocellular Carcinoma Development

Objective: To explore the potential mechanism of HBX regulatesmiR-101expression that plays important roles in gene regulation duringhepatocarcinogenesis.Methods: The expression of miR-101in HBV-related HCC tissuesand HCC cells was evaluated by Real-time PCR or Western blot. The directtarget of miR-101, DNA methyltransferase3A (DNMT3A), was identifiedin silico and validated using a3-UTR reporter assay. MiR-101wasfunctionally characterized in cells with transiently altered miR-101expression.Results: HBX expression was found to have a significant inversecorrelation with miR-101expression in HBX-expressing HepG2comparedto control HepG2cells. MiR-101expression was frequentlydown-regulated in HBV-related HCC tissues compared to adjacentnoncancerous hepatic tissues and had a significant inverse correlation with DNMT3A expression in HBV-related HCCs. Further characterization ofmiR-101revealed that it negatively regulated DNA methylation partlythrough targeting DNMT3A. HBX-mediated miR-101down-regulation andDNMT3A up-regulation supported the enhanced DNA methylation ofseveral tumor-suppressor genes in HBX-expressing cells.Conclusions: Our studies demonstrating the deregulation of miR-101expression by HBX may provide novel mechanistic insights intoHBV-mediated hepatocarcinogenesis and identifies a potentialmiRNA-based targeted approach for treating HBV-related HCC.