ATRA alleviates doxorubicin-induced cardiomyocyte ferroptosis by suppressing KEAP1-mediated NRF2 degradation

Abstract Objective Doxorubicin (DOX), a first-line anthracycline chemotherapeutic agent, is limited by dose-dependent cardiotoxicity. Ferroptosis is increasingly implicated in DOX-induced cardiomyocyte injury, yet effective strategies to suppress this process remain limited. This study investigated whether all-trans retinoic acid (ATRA) mitigates DOX-induced cardiomyocyte ferroptosis and defined the underlying mechanism. Methods We assessed the effects of ATRA on DOX-induced cardiomyocyte ferroptosis in vitro and in vivo using western blotting, quantitative real-time PCR, malondialdehyde (MDA) assays, glutathione (GSH) measurements and lipid peroxidation analysis. Loss-of-function models, cycloheximide chase assays, proteasome inhibition assays, molecular docking and co-immunoprecipitation were used to determine how the NRF2–SLC7A11 pathway mediates the protective effect of ATRA. Results DOX reduced cell viability, depleted GSH, increased MDA and downregulated SLC7A11 in cardiomyocytes. These effects were reversed by ATRA in vitro and in vivo. The anti-ferroptotic effect of ATRA was lost in SLC7A11-deficient and NRF2-deficient cells, indicating that the NRF2-SLC7A11 axis is required for protection. Mechanistically, ATRA stabilised NRF2 by reducing NRF2-KEAP1 interaction and proteasomal degradation. Co-immunoprecipitation showed that ATRA weakened the interaction between KEAP1 and NRF2. Molecular docking and mutagenesis suggested that KEAP1 Arg415 is functionally required for ATRA-mediated disruption of the KEAP1–NRF2 interaction. In vivo, ATRA increased myocardial NRF2 expression, suppressed DOX-induced ferroptosis and improved cardiac function, as shown by higher left ventricular ejection fraction and fractional shortening. Conclusion ATRA attenuates DOX-induced cardiomyocyte ferroptosis by disrupting KEAP1-mediated NRF2 degradation and activating the NRF2-SLC7A11 antioxidant pathway. These findings identify ATRA as a candidate cardioprotective strategy for anthracycline-related cardiac injury, pending further mechanistic and translational validation.