Transfection of HCVc improves hTERT expression through STAT3 pathway by epigenetic regulation in Huh7 cells

Previous studies showed that transient transfection of HCVc improved hTERT expression in hepatoma cell lines and it was noteworthy that phosphorylated signal transducer and activator of transcription 3 (pSTAT3) and DNA methyltransferases (DNMTs) were up regulated simultaneously. This study was designed to investigate the role of epigenetic regulation in the process of hTERT up regulation after HCVc transfection. Q-PCR and Western blot were used to analyze the expression of pSTAT3, DNMT1, and hTERT after the transfection of HCVc in hepatoma cell line Huh7. Proliferation and hTERT activity of Huh7 after HCVc transfection were examined by CCK8 and ELISA, respectively. Then, we blocked the JAK/STAT3 pathway or inhibited DNMT1 expression to investigate the regulation of pSTAT3, DNMT1, and hTERT. Methylation status of the promoter of hTERT gene was monitored by MS-PCR. Cell proliferation, hTERT expression level and activity of hTERT were promoted after HCVc transfection. The expression of pSTAT3 and DNMT1 were up-regulated simultaneously. DNMT1 and hTERT were down-regulated after blocking JAK/STAT3 pathway and the expression of hTERT weakened with DNMT1 inhibition. MS-PCR showed HCVc transfection increased the methylation level of hTERT promoter, and this effect was weakened after blocking the JAK/STAT3 pathway or with the treatment with DNMT1 inhibitor. HCVc transfection improved hTERT expression via epigenetic regulation. JAK/STAT3 pathway could be one of the essential factors in regulating DNMT1 expression during this process. J. Cell. Biochem. 113: 34193426, 2012. (C) 2012 Wiley Periodicals, Inc.