The effect of hepatitis B virus X gene transfection on expression of human telomerase reverse transcriptase mRNA in human bile duct carcinoma cell lines

Abstract

To study the effect of Hepatitis B virus X (HBx) gene transfection on expression of human telomerase reverse transcriptase (hTERT) mRNA in human bile duct carcinoma cell lines QBC939 and to elucidate the significance of cis-activation of hTERT mRNA by HBx gene on the carcinogenesis of bile duct. QBC939 were cultured in vitro and co-transfected with eukaryotic expression vector containing the HBx coding region and cloning vector containing enhanced green fluorescent protein (EGFP) coding sequence using liposome-mediated gene transduction technique. Thirty six hours after transfection, EGFP expression, the indicator of successful transfection in cells, was determined. Flow cytometry was applied to determine the transfection efficiency. Cells were harvested and total RNA was extracted with TRI(ZOL) Reagent. The expression of hTERT mRNA in QBC939 was assayed by Reverse Transcription Polymerase Chain Reaction. The expression of HBx protein in QBC939 was detected by immunocytochemistry staining and western blotting. The transfection efficiency was 29.6% for both HBx expression vector and vector control group. The expression of hTERT mRNA was significantly increased when transfected with HBx expression vector than that transfected with OPTI-MEM medium and vector only. The expression of HBx protein could only be found in the cells when transfected with HBx expression vector by immunocytochemistry staining and western blotting. HBx gene transfection may up-regulate the transcriptional expression of hTERT mRNA in bile duct carcinoma cells. The cis-activation of hTERT gene by HBx gene is primary mechanism for carcinogenesis of biliary epithelia after HBV infection.