Inhibition of hepatitis C virus replication in HepG2 cells via modulation of the Raf-1 and interferon-alpha signaling pathways by thymoquinone

Hepatitis C virus (HCV) infection is a significant global health concern, as both acute and chronic hepatitis caused by HCV can lead to liver cancer and long-term liver damage. Thymoquinone (TQ), the active compound found in the remarkable herb Nigella sativa, has various anti-inflammatory and antiproliferative effects. In this study, we investigated the effect of TQ on the interferon-alpha (IFN-α) pathway and its ability to prevent HCV replication in the HepG2 cell line. Our findings showed no significant alterations in cell viability or lactate dehydrogenase (LDH) production in TQ-treated cells, while significant alteration in both factors was detected in cells treated with Sovaldi, the most commonly used drug for treatment of HCV infection. Interestingly, the level of the HCV NS5A protein was significantly reduced in infected cells treated with either TQ or Sovaldi in a dose-dependent manner. The expression of phosphorylated Raf-1 (phospho-Raf-1) and phospho-Mek-1 in infected cells was inhibited by TQ treatment, and the potential interaction between TQ and Ref-1 was confirmed by a molecular docking simulation. Unlike autophagy-related 12 (Atg12), the expression of LC3B in infected cells was also inhibited in a dose-dependent manner by TQ treatment. Conversely, the levels of interleukin-27 (IL-27) and interferon-alpha (IFN-α) in infected cells were significantly increased in a time- and dose-dependent manner by TQ treatment. These data suggest that TQ exerts antiviral effects in HepG2 cells by disrupting HCV replication through targeting of the Raf-1 signaling pathway and promoting the overproduction of IL-27 and IFN-α in infected cells.