Effect of hepatitis B virus X in inhibiting the apoptosis of trophoblastic cells and its potential mechanism / 西安交通大学学报(医学版)

ABSTRACT

【Objective】 To investigate the relationship between hepatitis B virus X （HBx） protein and EGFR promoter， and the role of HBx protein in activating EGFR/PI3K/p-Akt signaling pathway and inhibiting apoptosis. 【Methods】 EGFR promoter plasmids were constructed and the relationship between HBx and EGFR promoters was characterized using a luciferase reporter assay. EGFR-overexpressing trophoblast cells were constructed， and EGFR expression in the overexpressing cells was knocked down using EGFR shRNA. The expression and localization of EGFR/PI3K/p-Akt were detected by Western blotting and confocal laser microscopy. Cell apoptosis was analyzed using flow cytometry. HBV plasmids carrying either full-length HBx or HBx with a deletion mutation （ΔHBx） and HBx plasmids were transfected into two types of trophoblast cells； HBx and PI3K/p-Akt protein expressions were detected by Western blotting. Cell apoptosis was analyzed using flow cytometry. 【Results】 Co-transfection of HBx and EGFR promoter plasmids in JEG-3 and HTR-8/Svneo cells significantly elevated the expression of EGFR promoter driven luciferase compared with the control group （P<0.01）. In EGFR-overexpressing cells， the expression of PI3K/p-Akt was significantly increased （P<0.01）， whereas the apoptosis rate was significantly decreased for JEG-3 cells and HTR-8/Svneo cells （both P<0.01）. These results were reversed in the EGFR-knock down group. When the intracellular HBx protein was expressed in JEG-3 and HTR-8 cells， PI3K/p-Akt protein expression was significantly increased （both P<0.05）， and the proportion of apoptosis was significantly decreased （both P<0.05）. 【Conclusion】 In placental trophoblast cells， HBx protein activates the expression of EGFR by acting on the EGFR promoter， and inhibits the apoptosis of trophoblast cells via the downstream EGFR/PI3K/p-Akt signaling pathway.