Hepatitis B Virus X Protein Promotes The Expression Of The Insulin-like Growth Factor Ⅱ Gene Via Inducing Hypomethylation Of P3Promoter In Hepatocellular Carcinoma

Purpose:Objective To explore the involvement of HBx in P3-driven mRNA overexpression andunderlying epigenetic mechanism.Methods:①P3mRNA, HBx mRNA, P3methylation status，and clinicopathologic features wereanalyzed in human hepatocellular carcinoma(HCC) samples with and without HBV infectionusing quantitative RT-PCR and bisulfite sequencing；②P3mRNA and P3methylation wereexamined in HepG2-HBx cells stably overexpressing HBx；③Luciferase assays were performedusing P3promoter-luciferase constructs in HepG2cells cotransfected with plasmid expressingHBx, and the effects of HBx on transcriptional activity and methylation of this promoter wereanalyzed.Results:①Compared with those of HBV-negative specimens, P3mRNA levels and meanmethylation of the17CpG sites in P3promoter were higher and lower in HBV-positivespecimens, respectively；②P3transcript abundance was positively correlated to HBx expressionand negatively correlated to P3methylation, respectively；③The similar epigenetic results of P3transcript were also observed in HepG2-HBx cells. Transfected HBx significantly decreased P3methylation level and increased its activity. Furthermore, HBV-positive HCC patients wereassociated more frequently with tumor embolus of portal vein and poor differentiation.Conclusion: HBx expression may promote IGF-II expression by inducing hypomethylation ofP3promoter in hepatocellular carcinoma and be associated with a poor Clinical outcomes ofHCC patients, which provides useful information for understanding the mechanism ofHBx-mediated HCC.