Targeting NDUFS4 Disrupts Oxidative Phosphorylation and Induces Ferroptosis in Olaparib-Resistant Prostate Cancer

Resistance to poly(ADP-ribose) polymerase inhibitors (PARPi) remains a major challenge in the treatment of advanced prostate cancer. Although metabolic rewiring has been implicated in this process, the molecular drivers and therapeutic vulnerabilities underlying this adaptation remain poorly defined. We integrated transcriptomic, functional, and clinical analyses to identify mitochondrial regulators of PARPi resistance. RNA sequencing and gene set enrichment analysis revealed robust enrichment of oxidative phosphorylation (OxPhos) pathways in PARPi-resistant prostate cancer cells, with consistent upregulation of NDUFS4, a nuclear-encoded subunit of electron transport chain complex I. Elevated NDUFS4 expression correlated with poor survival in patient cohorts from The Cancer Genome Atlas and SU2C/PCF. Functional analyses demonstrated that genetic knockdown of NDUFS4 impaired complex I activity, reduced mitochondrial mass, and resensitized resistant cells to olaparib. Pharmacologic targeting of NDUFS4 using the niclosamide analog ARVib-7 phenocopied genetic depletion, suppressing mitochondrial respiration and enhancing olaparib efficacy to inhibit the growth of resistant spheroids. Both NDUFS4 silencing and ARVib-7 treatment induced ferroptotic stress, as evidenced by intracellular iron accumulation and altered expression of ferroptosis-associated markers, including COX2, CHAC1, NRF2, and GPX4. These findings identify NDUFS4 as a key mediator of PARPi resistance and a therapeutic vulnerability in advanced prostate cancer. Targeting NDUFS4 disrupts OxPhos and induces ferroptosis, providing a strong rationale for combination strategies with PARPis to overcome drug resistance.