Metformin inhibits hepatitis B virus protein production and replication in human hepatoma cells

Hepatitis B virus surface antigen (HBsAg) plays an important role in maintaining the tolerance and may interfere with host innate and adaptive immune responses; therefore, novel therapeutic strategies to reduce HBsAg loads in patients infected with hepatitis B virus (HBV) are emerging as an attractive but challenging issue. Metformin could regulate hepatic metabolism while the latter interacts with HBV infection. We hypothesized that metformin could affect HBsAg expression and HBV replication and may work synergistically when combined with current antivirals. In our study, a notably inhibitory effect on HBsAg production, as well as a moderate inhibition in HBV replication and HBeAg expression was observed following metformin treatment. The 50% effective concentration (EC50) for extracellular HBsAg and intracellular HBsAg in HBV-producing HepG2.2.15 cells was 2.85 mm and 2.75 mm, respectively, with a similarly selective index of about 18. When administered in combination, metformin enhanced the inhibitory effects of interferon-α2b on HBsAg expression and HBV replication and provided a complimentary role in HBsAg expression for lamivudine (LMV). This novel action of metformin derives partially from its inhibition on multiple HBV cis-acting elements. By the virtues of preferably hepatocyte distribution and safety profile, collectively, our results suggest that metformin would be potentially clinically helpful as an HBsAg production inhibitor.