The xCT/CD98 complex suppresses ferroptosis in pan-cancer via a non-canonical RACK1-mediated iron homeostasis pathway

Evasion of cell death drives tumor recurrence and metastasis, yet pan-cancer mechanisms of ferroptosis remain limited. We treated multiple tumor cell lines with ferroptosis inducers or anticancer agents and utilized post-translational modification proteomics including ubiquitination, acetylation, and phosphorylation during ferroptosis. We identify a significant increase in K280 ubiquitination of the ribosomal protein RACK1. Further pan-cancer cellular experiments suggest that RACK1 may suppress ferroptosis by regulating iron export via FPN1. Immunoprecipitation coupled with liquid chromatography-mass spectrometry reveals RACK1 interactions with CD98 and TRIM21. Ferroptosis inducers promote RACK1 K280 ubiquitination via TRIM21, and mechanistic studies confirm that TRIM21-mediated RACK1 ubiquitination affects cellular iron homeostasis. These findings indicate that, beyond the canonical GPX4 pathway, the xCT/CD98 complex can inhibit ferroptosis via the TRIM21/RACK1/FPN1 axis. Targeting RACK1 offers a potential therapeutic strategy to sensitize tumors to ferroptosis and overcome therapy resistance across multiple cancer types and in people with cancer.