Regulation of interferon signaling and HCVRNA replication by extracellular matrix

Although interferon (IFN)based treatment of patients with chronic hepatitis C virus (HCV) infection is widely applied, treatment resistance is often observed in patients with advanced liver fibrosis. Given that the molecular mechanisms of IFN resistance in liver fibrosis remain elusive, the present study investigated the effects of extracellular matrix (ECM) on IFN signaling in hepatic cells. The native HuH7 human hepatoma cell line and HuH7 cells were stably transfected with fulllength HCVRNA fused with Renilla luciferase (OR6 cells) were cultured on ECMcoated dishes or noncoated plastic dishes (NDs), and treated with human IFNα. In Huh7 cells cultured on coated dishes, the IFNstimulated response element (ISRE) luciferase activity was measured following ISRE plasmid transfection and the expression of IFNstimulated genes (ISG) were significantly lower than those in cells cultured on NDs. In addition, after IFNα treatment, the amount of HCVRNA and viral protein produced by OR6 cells cultured on coated dishes was higher than that produced by cells cultured on NDs. When cells were treated with β1integrinblocking antibody to disrupt the cellmatrix interaction, the ISRE luciferase activity was restored, and the protein expression of ISG was increased, while that of HCV proteins was suppressed. Treatment of cells with integrinlinked kinase (ILK) inhibitor or focal adhesion kinase (FAK) inhibitor restored the ISRE luciferase activity and expression of ISG proteins. These results suggested that β1integrinmediated signals affected the IFN signaling and promoted HCV replication. Therefore, the accumulation of ECM in liver fibrosis may impair IFN signaling through β1integrinmediated signaling involving ILK and FAK.