Microenvironmental Prostaglandin F2α Antagonizes FSP1 in Cancer Cells to Sensitize Tumors to Ferroptosis and Immunotherapy.

Induction of ferroptosis is a potential strategy for treating cancer and improving the efficacy of immunotherapy. Ferroptosis is driven by excessive peroxidation of polyunsaturated fatty acid-containing phospholipids, suggesting that microenvironmental lipid metabolites may regulate ferroptotic sensitivity. By integrating single-cell and bulk transcriptomics from immunotherapy cohorts, we identified the prostaglandin (PG) pathway as closely associated with tumor ferroptosis and therapeutic efficacy. Further screening revealed PGF2α as a potent endogenous ferroptosis sensitizer. Mechanistically, microenvironmental PGF2α bound to ferroptosis suppressor protein 1 (FSP1) at alanine 295 (A295) and inhibited its enzymatic activity, leading to lipid peroxidation accumulation upon ferroptotic stimuli. Preclinically, PGF2α supplementation or FSP1 ablation enhanced tumoral ferroptosis, potentiated CD8+ T cell-mediated immunity, and suppressed tumor progression in immunocompetent mice. Moreover, PGF2α improved immunotherapy efficacy across multiple mouse models, including subcutaneous allografts, Braf/Pten-driven spontaneous melanoma, and humanized mice. Clinically, a high PGF2α activity-related transcriptomic signature correlated with elevated ferroptosis and improved patient survival. Collectively, these findings establish PGF2α as a pro-ferroptotic metabolite and propose that targeting the PGF2α/FSP1 axis may offer an effective cancer immunotherapeutic strategy.