MUC1 drives ferroptosis resistance in ICC via Src-mediated FSP1 deubiquitination and myristoylation.

BACKGROUND: Intrahepatic cholangiocarcinoma (ICC) exhibits poor prognosis and limited therapeutic options. Ferroptosis represents a promising therapeutic strategy, yet resistance mechanisms remain poorly understood. This study investigated the role of mucin 1 (MUC1) in regulating ferroptosis sensitivity in ICC. METHODS: Bioinformatic analyses of GEO and TCGA datasets identified ferroptosis-related factors in ICC. MUC1 expression was validated in ICC cell lines and clinical specimens. Ferroptosis sensitivity was assessed through RSL3-induced cell death assays, lipid peroxidation measurements, and iron detection. Mechanistic studies employed immunoprecipitation-mass spectrometry, co-immunoprecipitation, kinase assays, and deubiquitination assays. In vivo efficacy was evaluated using subcutaneous tumor models. RESULTS: MUC1 was identified as a critical ferroptosis suppressor in ICC. MUC1 overexpression conferred RSL3 resistance by inhibiting lipid peroxidation and reducing ferrous iron accumulation, independent of the GPX4-glutathione pathway. Mechanistically, MUC1 recruited Src kinase, which phosphorylated deubiquitinating enzyme ubiquitin-specific protease 10 (USP10) at tyrosines 359 and 364, enhancing ferroptosis suppressor protein 1 (FSP1) deubiquitination at lysine 246 and stabilizing FSP1 protein. Concurrently, Src phosphorylated N-myristoyltransferase 1 (NMT1) at tyrosine 41, augmenting FSP1 membrane localization through myristoylation. This dual mechanism potentiated the FSP1- coenzyme Q10 (CoQ10) antioxidant system. MUC1 knockdown significantly enhanced ferroptotic sensitivity in vitro and suppressed tumor growth in vivo. CONCLUSIONS: MUC1 orchestrates ferroptosis resistance in ICC through the Src-USP10/NMT1-FSP1 axis. Targeting this signaling cascade represents a potential therapeutic strategy for overcoming ferroptosis resistance in ICC. KEY POINTS: MUC1 suppresses ferroptosis in ICC via Src-mediated post-translational modifications. Src phosphorylation of USP10 stabilizes FSP1 by removing K48-linked polyubiquitin. Src activates NMT1 to enhance FSP1 myristoylation and membrane localization.