Short-term tamoxifen administration improves hepatic steatosis and glucose intolerance through JNK/MAPK in mice

Nonalcoholic fatty liver disease (NAFLD) which is a leading cause of chronic liver diseases lacks effective treatment. Tamoxifen has been proved to be the first-line chemotherapy for several solid tumors in clinics, however its therapeutic role in NAFLD has never been elucidated before. In vitro experiments, tamoxifen protected hepatocytes against sodium palmitate-induced lipotoxicity. In male and female mice fed with normal diets, continuous tamoxifen administration inhibited lipid accumulation in liver and in blood, and improved glucose and insulin intolerance. Short-term tamoxifen administration largely improved hepatic steatosis and insulin resistance, however the phenotypes manifesting inflammation and fibrosis remained unchanged in abovementioned models. In addition, mRNA expressions of genes related to lipogenesis, inflammation and fibrosis were downregulated by tamoxifen treatment. Moreover, the therapeutic effect of tamoxifen on NAFLD was not gender or ER dependent, as male and female mice with metabolic disorders shared no difference in response to tamoxifen and ER antagonist (fulvestrant) didn’t abolish its therapeutic effect as well. Mechanistically, RNA-sequence of hepatocytes isolated from fatty liver revealed that JNK/MAPK signaling pathway was inactivated by tamoxifen. Pharmacological JNK activator (anisomycin) partially deprived the therapeutic role of tamoxifen in treating hepatic steatosis, proving tamoxifen improved NAFLD in a JNK/MAPK signaling dependent manner. Comparative gene expression profiling analysis of RNA-seq data for primary hepatocytes isolated from MCD diet-induced NASH mice administrated with tamoxifen or vehicle for consecutive 5 days