Farnesoid X Receptor Antagonizes JNK Signaling Pathway in Liver Carcinogenesis by Activating SOD3

The farnesoid X receptor (FXR) is a key metabolic and homeostatic regulator in the liver. In the present work, we identify a novel role of FXR in antagonizing c-Jun N-terminal kinase (JNK) signaling pathway in liver carcinogenesis by activating superoxide dismutase 3 (SOD3) transcription. Compared with wild-type mouse liver, FXR−/− mouse liver showed elevated JNK phosphorylation. JNK1 deletion suppressed the increase of diethylnitrosamine-induced tumor number in FXR−/− mice. These results suggest that JNK1 plays a key role in chemical-induced liver carcinogenesis in FXR−/− mice. We found that ligand-activated FXR was able to alleviate H2O2 or tetradecanoylphorbol acetate-induced JNK phosphorylation in human hepatoblastoma (HepG2) cells or mouse primary hepatocytes. FXR ligand decreased H2O2-induced reactive oxygen species (ROS) levels in wild-type but not FXR−/− mouse hepatocytes. FXR knockdown abolished the inhibition of 3-[2-[2-chloro-4-[[3-(2,6-dichlorophenyl)-5-(1-methylethyl)-4-isoxazolyl]methoxy]phe...