Dual Compartmentalization of GSTA4 Suppresses Ferroptosis to Drive Antiandrogen Resistance in Prostate Cancer

Resistance to second-generation antiandrogens poses a major therapeutic challenge in castration-resistant prostate cancer (CRPC). While ferroptosis evasion has been implicated in treatment failure, the key molecular determinants driving this evasive process are poorly understood. Using integrated multi-omics analyses of resistant models and patient specimens, we identify glutathione S-transferase alpha 4 (GSTA4) as a pivotal ferroptosis suppressor that is associated with adverse clinical outcomes and drives antiandrogen resistance via a dual compartmentalization mechanism. Our data demonstrate that GSTA4 not only detoxifies the lipid peroxidation product 4-hydroxynonenal in the cytosol but also translocates to the mitochondria under ferroptotic stress. GSTA4 interacts with PGAM5 to prevent the dephosphorylation of Drp1 at Ser637, thereby maintaining mitochondrial fitness and suppressing ferroptosis. This spatially coordinated defense program is crucial for antiandrogen resistance, as GSTA4 knockdown sensitizes tumors to antiandrogen therapy. Virtual screening and surface plasmon resonance assays identify metformin as a candidate GSTA4 inhibitor. Targeting GSTA4 with metformin restores ferroptosis sensitivity and reverses antiandrogen resistance both in vitro and in vivo. Our findings uncover a spatially coordinated anti-ferroptotic mechanism underlying antiandrogen resistance and highlight targeting GSTA4 as a promising combination strategy for CRPC treatment.