Targeting Hsp70 triggers ferroptosis: a novel anti-cancer mechanism of a marine natural product in prostate cancer.

Prostate cancer (PCa) remains one of the most common malignant tumors among men worldwide, typically relying on the androgen receptor (AR) signaling pathway. Inducing ferroptosis, a novel form of iron-dependent cell death, represents a promising strategy; however, its regulation by AR signaling is complex. The molecular chaperone heat shock protein 70 (HSP70) is critical for AR stability and function, yet its role as a therapeutic target in this context is underexplored. The anti-proliferative effect of the compound nidurufin (Nid) was assessed across PCa cell lines using MTT, clonogenic, and 3D spheroid assays. Ferroptosis was evaluated by transmission electron microscopy, reactive oxygen species (ROS) detection, and lipid peroxidation analysis. Mechanistic insights were gained through Western blot, qPCR, immunofluorescence, ChIP-qPCR, molecular docking, and cellular thermal shift assay (CETSA). In vivo efficacy was validated in a zebrafish xenograft model. Nid exhibited potent, selective anti-proliferative activity against AR-positive PCa cells, particularly 22Rv1 (IC₅₀ = 10.30 μM), and induced ferroptosis characterized by mitochondrial shrinkage and ROS accumulation. Mechanistically, Nid did not bind to AR, but it directly bound to HSP70, disrupting its chaperone function and leading to AR protein destabilization and transcriptional downregulation. This consequently suppressed the expression of the AR-target gene membrane-associated O-acyltransferase domain protein 2 (MBOAT2), a key ferroptosis suppressor enzyme. ChIP-qPCR confirmed AR directly binds the MBOAT2 promoter, and Nid treatment reduced this enrichment. In vivo, Nid significantly inhibited tumor growth and metastasis in a zebrafish xenograft model. Our study identifies Nid as a novel HSP70-targeted compound that triggers ferroptosis by disrupting the HSP70-AR-MBOAT2 axis. This work not only reveals a previously unrecognized connection between protein chaperone function and ferroptotic susceptibility but also positions HSP70 as a compelling therapeutic target for overcoming AR-pathway dependency in PCa.