[Study on the effect and mechanism of hepatitis B virus X protein transactivates gene 4 in HepG2 cell apoptosis]

Objective: To investigate the effect and mechanism of XTP4 gene in apoptotic hepatoblastoma HepG2 cell line. Methods: HepG2 cells were transiently transfected with small interfering RNA of XTP4 genes, plasmid pcDNA3.1/myc-His(-) A-XTP4, and hepatitis B virus X protein transactivated x gene 4 (HBX protein trans-activate gene4, XTP4) and their respective negative controls. After 48h, the overexpression and interference expression condition of XTP4 in HepG2 cells were detected by Western blot. HepG2 cells apoptosis was detected by flow cytometry. The expression levels of apoptosis-related proteins P53, Bcl-2, Bax and Caspase-3 in HepG2 cells were detected by Western blot, and Bcl-2/Bax ratio was calculated. The chemiluminescence assay was used to detect activity of caspase-3 in HepG2 cells. The measured data were presented as (x ± s), and independent sample t-test was used for comparison between the two groups. Results: HepG2 cells had successfully achieved the overexpression and interference expression of XTP4 protein. Compared with the control group, the overexpression of XTP4 in HepG2 cells had significantly decreased the number of apoptotic cells (P < 0.05), and increased Bcl-2/Bax (P < 0.05) ratio, but decreased the expression of P53 protein (P < 0.05). The protein expression of Caspase-3 and activity of caspase-3 was decreased (P < 0.05). However, interference with XTP4 expression in HepG2 cells had significantly increased the number of apoptotic cells (P < 0.05) and decreased Bcl-2/Bax (P < 0.05) ratio, but increased the expression of P53 protein (P < 0.05). The protein expression of Caspase-3 and activity of caspase-3 was increased (P<0.05). Conclusion: In HepG2 apoptosis XTP4 has inhibitory effect, and its effect on inhibiting HepG2 apoptosis may be achieved by regulating the Bcl-2/Bax ratio, and the P53 protein may be involved.