High-fat diet aggravates colitis-associated carcinogenesis by evading ferroptosis in the ER stress-mediated pathway.

Ferroptosis, a type of programmed cell death caused by lipid peroxidation has recently been observed in colitis. Whether a high-fat diet (HFD) affects ferroptosis and whether it contributes to colitis-associated carcinogenesis (CAC) has not been explored. We found iron, lipid peroxidation, and ferroptotic markers to be elevated in AOM/DSS (azoxymethane/dextran sulfate sodium)-induced mouse CAC model. Transmission electron microscopy also confirmed the occurrence of ferroptosis in colonic tissues. Treatment with the ferroptosis inhibitor, ferrostatin-1 increased the incidence of CAC. Compared with iso-caloric control mice, HFD mice exhibited increased tumor number and a higher degree of dysplasia following repression of lipid peroxidation and ferroptosis marker expression in mouse colon tissue. Furthermore, ferroptosis markers were negatively correlated with the tumor number in mice. In vitro, a lipid mixture blocked ferroptosis in various colorectal cancer cell lines and inhibited GSH degradation by negatively regulating CHAC1, a target in ER stress signaling. Finally, the ferroptosis inducer partly abolished the pro-tumor effect of the HFD on CAC in vivo. Collectively, these findings suggest that a HFD aggravates CAC through the evasion of ferroptosis in the ER stress-mediated pathway and provide a new perspective for CAC prevention in the future.