Glutathione peroxidase 4 suppresses manganese-dependent oxidative stress to reduce colorectal tumorigenesis.

The role of glutathione peroxidase 4 (GPX4) in ferroptosis and various cancers is well-established; however, its specific contribution to colorectal cancer has been unclear. Surprisingly, in a genetic mouse model of colon tumors, the deletion of GPX4 specifically in colon epithelial cells increased tumor burden but decreased oxidized glutathione. Notably, this specific GPX4 deletion did not enhance susceptibility to dextran sodium sulfate (DSS)-induced colitis in mice with varied iron diets but showed vulnerability in mice with a vitamin E-deficient diet. Additionally, a high manganese diet heightened susceptibility, while a low manganese diet reduced DSS-induced colitis in colon epithelial-specific GPX4-deficient mice. Strikingly, the low manganese diet also significantly reduced colorectal cancer formation in both colon epithelial-specific GPX4-deficient and wildtype mice. Mechanistically, antioxidant proteins, especially manganese-dependent superoxide dismutase (MnSOD or SOD2), correlated with disease severity. Treatment with tempol, a superoxide dismutase mimetic radical scavenger, suppressed GPX4 deficiency-induced colorectal tumors. In conclusion, the study elucidates the critical role of GPX4 in inhibiting colorectal cancer progression by regulating oxidative stress in a manganese-dependent manner. The findings underscore the intricate interactions between GPX4, dietary factors, and their collective influence on colorectal cancer development, providing potential insights for personalized therapeutic strategies.