The Effect Of HBx On SOCS-1CpG Island Methylation And Its Expression

Objective To investigate the effect of hepatitis B virus X--protein(HBx) on the promoter CpG island methylation and its expression of suppressors of cytokine signaling-1(SOCS-1) in mmortalized human derived non-tumor liver cell line QSG7701.To explore the possible mechanism that HBx induce hepatocyte carcinogenisis.Methods QSG7701cells were transfected with the recombinat plasmid pcDNA-X or control plasmid pcDNA3.0. Medium containing G418were used to screen stably transfected cell clones. The expression of HBV-X mRNA in the HBV-X stably transfected QSG7701cells was detected by semi-quantitative reverse-transcribe polymerase chain reaction(RT-PCR), and the expression of HBx protein was confirmed by Western blot. Expression of SOCS-1mRNA in three celllines was detected by Real-time quantitative PCR (real time-PCR), and expression of SOCS-1protein was confirmed by Western blot. The promotor region CpG island methylation status of SOCS-1was detected by methylation-specific polymerase chain reaction (MSP).Results RT-PCR、Western blot showed that pcDNA-x/QSG7701which were transfected with recombinat plasmid pcDNA-X existed the expression of HBx mRNA and protein. There were no expression of HBx mRNA and protein in untransfected QSG7701cells and pcDNA3.0/QSG7701cells which were transfected with control plasmid pcDNA3.0. Real-time quantitative PCR and Western blot analysis showed that SOCS-1mRNA and SOCS-1protein were downregulated in pcDNA-X/QSG7701cells than that in pcDNA3.0/QSG7701cells and untransfected QSG7701cells. Promoter region methylation of SOCS-1existed in cells which were transfected with recombinat plasmid pcDNA-X. No promoter region methylation of SOCS-1was found in pcDNA3.0/QSG7701cells and untransfected QSG7701cells which were transfected with control plasmid pcDNA3.0.Conclusions HBx could down-regulate the expression of SOCS-1mRNA and protein in transfected QSG7701cells. Hepatitis B virus x protein (HBx) may make SOCS-1promoter CpG island methylation and down-regulate SOCS-1expression, which may be one of mechanisms that HBx induce hepatocyte carcinogenesis.