ATF7IP inhibits Sorafenib-induced ferroptosis in hepatocellular carcinoma cells by inhibiting CYB5R2 transcription and stabilizing PARK7 protein
Ferroptosis, an iron-dependent form of programmed cell death, arises from the accumulation of lipid peroxides at toxic levels. Sorafenib, a first-line treatment for advanced hepatocellular carcinoma (HCC), shows limited clinical efficacy due to drug resistance. However, the mechanisms underlying Sorafenib resistance, especially related to ferroptosis, remain poorly understood. In this study, we extend our previous research by identifying activating transcription factor 7-interacting protein (ATF7IP) as a key inhibitor of ferroptosis. ATF7IP depletion promotes Sorafenib-induced ferroptosis, resulting in decreased cell viability, reduced cellular glutathione level, increased lipid peroxidation, and altered mitochondrial crista structure. Notably, ATF7IP knockdown showed cooperative effects with Sorafenib in inhibiting HCC growth in mice. Mechanistically, ATF7IP interacts with SET domain bifurcated histone lysine methyltransferase 1 (SETDB1) to epigenetically silence the transcription of cytochrome b5 reductase 2 (CYB5R2), thereby reducing cellular Fe2+ levels. Meanwhile, ATF7IP inhibits Sorafenib-induced ferroptosis also by stabilizing the antioxidant sensor Parkinsonism-associated deglycase (PARK7) protein which preserves the transsulfuration pathway to produce glutathione (GSH). In conclusion, our findings identify ATF7IP as a critical ferroptosis inhibitor and represent ATF7IP as a novel therapeutic target for Sorafenib-based combination therapies of HCC. Overall design: Examination of gene transcription in Control cells, ATF7IP knockdown cells, and SETDB1 knockdown HepG2 cells under Sorafenib treatment