SESN2 promotes ferroptosis in bladder cancer by negatively regulating the NRF2/FSP1 signaling axis

Background: Bladder cancer (BLCA) shows intrinsic ferroptosis resistance. Sestrin2 (SESN2) regulates ferroptosis in other diseases, but its role in BLCA is unknown. In this study, we sought to determine whether SESN2 contributes to the intrinsic ferroptosis resistance of BLCA and to elucidate the underlying molecular mechanisms.

Methods: SESN2 expression was measured in BLCA tissues, RT4 cells, T24 cells, and normal controls by quantitative real-time polymerase chain reaction, western blot, and immunofluorescence. Ferroptosis markers (glutathione (GSH), malondialdehyde (MDA), and Fe2+) and nuclear factor erythroid 2-related factor 2 (NRF2)/ferroptosis suppressor protein 1 (FSP1) levels were assessed in tissues and cells. RT4 cells were transfected with SESN2 overexpression plasmid, and changes in GSH, MDA, and NRF2/FSP1 were examined. Inhibitors ML385 (NRF2) and iFSP1 (FSP1) were used to verify pathway involvement.

Results: SESN2 was downregulated in BLCA tissues and cells. BLCA displayed a ferroptosis-resistant phenotype (higher GSH, lower MDA and Fe2+) with elevated NRF2/FSP1 expression. SESN2 overexpression reduced GSH, increased MDA and Fe2+, and downregulated NRF2/FSP1 expression. Inhibitor treatment further lowered NRF2/FSP1 expression and partially reversed the changes in GSH, MDA, and Fe2+.

Conclusions: SESN2 is downregulated in BLCA and promotes ferroptosis by negatively regulating the NRF2/FSP1 axis. This study identifies a novel role of SESN2 in BLCA ferroptosis and suggests targeting this pathway as a potential therapeutic strategy.