Saikosaponin C exerts anti-HBV effects by attenuating HNF1α and HNF4α expression to suppress HBV pgRNA synthesis.

OBJECTIVE: Saikosaponin c (SSc), a compound purified from the traditional Chinese herb of Radix Bupleuri was previously identified to exhibit anti-HBV replication activity. However, the mechanism through which SSc acts against HBV remains unknown. In this study, we investigated the mechanism of SSc mediated anti-HBV activity. METHODS: HepG2.2.15 cells were cultured at 37 â„ƒ in the presence of 1-40 µg/mL of SSc or DMSO as a control. The expression profile of HBV markers, cytokines, HNF1α and HNF4α were investigated by real-time quantitative PCR, Elisa, Western blot and Dot blotting. Knockdown of HNF1α or HNF4α in HepG2.2.15 cells was mediated by two small siRNAs specifically targeting HNF1α or HNF4α. RESULTS: We found that SSc stimulates IL-6 expression, leading to attenuated HNF1α and HNF4α expression, which further mediates suppression of HBV pgRNA synthesis. Knockdown of HNF1α or HNF4α in HepG2.2.15 cells by RNA interference abrogates SSc's anti-HBV role. Moreover, SSc is effective to both wild-type and drug-resistant HBV mutants. CONCLUSION: SSc inhibits pgRNA synthesis by targeting HNF1α and HNF4α. These results indicate that SSc acts as a promising compound for modulating pgRNA transcription in the therapeutic strategies against HBV infection.