Hepatitis C virus core protein interacts with zinc finger E-box binding homeobox 2 to inhibit E-cadherin expression

Abstract

Objective To investigate the molecular mechanism by which hepatitis C virus (HCV) core protein represses the expression of E-cadherin by interacting with zinc finger E-box binding homeobox 2 (ZEB2). Methods A HepG2 cell line stably expressing HCV core protein was constructed by transfecting the cells with pCore-3FLAG and G418 screening. The expression levels of ZEB2 and E-cadherin in the transfected cells were examined with RT-PCR and Western blotting, and the promoter activity of E-cadherin was assayed using a dual luciferase system. The interaction of HCV core protein with ZEB2 was detected by immunoprecipitation, and the binding of ZEB2 with E-cadherin promoter was determined by chromatin immuoprecipitation. Results Compared with the control cells, the cells transiently and stably expressing HCV core protein both showed significantly decreased expression of E-cadherin (P < 0.01) and increased ZEB2 expression (P < 0.05) at both the protein and mRNA levels. HepG2 cells transfected with HCV core protein exhibited obviously lowered luciferase activity driven by E-cadherin promoter (P < 0.01), while ZEB2 knockdown by RNA interference partly recovered the luciferase activity (P < 0.05). Immunoprecipitation results demonstrated that HCV core protein could bind directly to ZEB2. Chromatin immunoprecipitation assay showed that the presence of HCV core protein obviously enhanced the binding of ZEB2 to E-cadherin promoter. Conclusion HCV core protein increases the expression of ZEB2 and enhances its binding to E-cadherin promoter, and thus inhibits the expression of E-cadherin.

Keywords

• hepatitis c virus
• core protein
• hepatocellular carcinoma