Tamoxifen regulates ferroptosis of hepatocytes by targeting SLC1A5 to activate hepatic stellate cells and liver fibrosis.

Tamoxifen (TAM) is a commonly used drug for breast cancer treatment, mainly inhibiting estrogen receptors to prevent tumor growth. Although TAM has achieved remarkable effects in clinical treatment, recent studies have shown that TAM can cause drug-induced liver injury. However, it's still unclear whether long-term use of TAM can cause liver fibrosis. This study explores whether long-term administration of TAM can cause liver fibrosis and its mechanism. We found that TAM could induce liver injury in mice and significantly up-regulate the expression of activation markers of stellate cells, activating the TGF-β/smad signaling pathway. Additionally, TAM induced an inflammatory response and activated the NF-κB signaling pathway. More importantly, we demonstrated for the first time in vivo and in vitro that TAM-induced hepatocyte ferroptosis, accompanied by glutathione (GSH) depletion, reactive oxygen species (ROS) accumulation, and intracellular ferrous enrichment, and changes in the expression of ferroptosis-related proteins. Ferroptosis inhibitors such as ferrostatin-1 (Fer-1) and DFO ameliorated ferroptosis in hepatocytes. However, these ferroptotic events did not occur in macrophages and hepatic stellate cells (HSCs). Co-culture experiments showed that TAM-induced hepatocytes could increase expression of liver fibrosis-related proteins in HSCs, but this could be abolished by ferroptosis inhibitors. Bioinformatics analysis suggested TAM may regulate hepatocyte ferroptosis through solute carrier family 1 member 5 (SLC1A5). Downregulation of SLC1A5 could inhibit TAM-induced hepatocyte ferroptosis, thereby alleviating HSCs activation and the increased expression of ECM proteins. Our study suggests that TAM induces hepatocyte ferroptosis through SLC1A5, leading to HSC activation and liver fibrosis.