Inhibition of WNT signalling interferes with HCV replication

Abstract

Background and Aims: The tumor relevant wnt pathway activity is associated with higher HCV replication. HCV core and NS5 protein have recently been shown to induce wnt pathway activity, implicating a cause for progression to HCC. We now investigated if wnt pathway activity might affect HCV replication. Methods: For in vitro experiments the HCV replicon system expressing HCV genes NS3 to NS5B alone (Huh5–15) or in combination with firefly luciferase (LucUbiNeo-ET) was used. To promote wnt pathway activity the glycogen synthase kinase 3 beta (GSK3b) inhibitors Kenpaullone or SB216763 were used. Inhibition of the wnt pathway was achieved by use of either Quercetin or 4,5,6,7-tetrabromo-2-azabenzimidazole (TBB), an inhibitor of beta-catenin stabilizing kinase CK2, or by transient knockdown of beta-catenin by siRNA. Gene expression was measured by real time RT-PCR and Western Blot analysis. Wnt pathway activity was measured by a reporter assay for beta catenin related transcription (CRT assay). Results: Our results confirm that activity of the wnt pathway is increased in replicon cell lines compared to the replicon background cell line Huh7 and that the HCV protein NS5A is involved. Additionally we found that NS3B is able to increase Wnt pathway activity. Inhibition of the wnt signaling pathway by quercetin, TBB or siRNA directed against beta-catenin reduced HCV replication significantly without toxic effects on cultured cells. Moreover, activation of wnt pathway activity by inhibitors of GSK3b increased HCV replication. Conclusions: HCV replication induces wnt signaling which in turn seems to promote HCV replication. Therefore, inhibition of the wnt signaling pathway might not only represent a way to interfere with tumor growth but might also become a novel approach for HCV therapy.