F-53B exacerbates doxorubicin-induced cardiotoxicity by impairing NRF2-dependent ferroptosis defense

6:2 Chlorinated polyfluorinated ether sulfonate (F-53B), an emerging substitute for perfluorooctane sulfonate (PFOS), has raised increasing concern due to its environmental persistence, bioaccumulation, and potential health risks. Doxorubicin (DOX) is an effective anticancer drug whose clinical utility is limited by dose-dependent cardiotoxicity. However, the combined cardiac effects of F-53B and DOX, along with the underlying mechanisms, remain unclear. In this study, we demonstrated that subchronic exposure to F-53B alone at 0.2 and 1 mg/kg/day by oral gavage for 8 weeks induced only mild subclinical myocardial injury without overt dysfunction or structural changes in mice. However, subchronic exposure to the same doses of F-53B exacerbated DOX-induced cardiac dysfunction, atrophy, and fibrosis. Consistently, in cultured cardiomyocytes, F-53B at 25 and 50 μM for 48h synergistically enhanced DOX-induced cytotoxicity, as evidenced by reduced cell viability and increased cell death. Both in vivo and in vitro, F-53B co-exposure suppressed the anti-ferroptosis regulators GPX4 and FTH1, promoted accumulation of ferrous iron (Fe²⁺), and elevated lipid peroxidation markers including 4-hydroxynonenal (4-HNE), lipid reactive oxygen species (lipid ROS), and malondialdehyde (MDA). The exacerbating effects of F-53B on cell death and lipid peroxidation were reversed by the ferroptosis inhibitor ferrostatin-1 (Fer-1), confirming ferroptosis dependence. Mechanistically, F-53B promoted the ubiquitin-mediated degradation of NRF2. Pharmacological activation of NRF2 by dimethyl fumarate (DMF) effectively counteracted the F-53B-induced suppression of GPX4 and FTH1, thereby alleviating ferroptosis and the ensuing cardiotoxicity. Collectively, our findings reveal the synergistic impact of F-53B and DOX on cardiotoxicity and elucidate the underlying mechanism involving the NRF2-mediated anti-ferroptosis pathway.