Therapy-induced PSMA2 Sensitizes Prostate Cancer Cells to Residual Androgen and Promotes Neuroendocrine Lineage Transformation

Aberrant activation of the androgen receptor (AR) pathway drives prostate cancer (PCa). Androgen deprivation therapy (ADT) and next-generation AR blockade (e.g., enzalutamide) are initially effective, but virtually all patients develop castration-resistant prostate cancer (CRPC), which frequently transitions to treatment-emergent neuroendocrine PCa (tNEPC) following AR suppression. The molecular logic that links AR blockade to lineage plasticity remains incompletely understood. Here, we identify PSMA2 (Proteasome Subunit Alpha 2) as a treatment-induced effector that mechanistically connects AR blockade to tNEPC evolution. Enzalutamide induces PSMA2 expression in AR-expressing PCa cells. Enforced PSMA2 expression accelerates HSP90 turnover, hypersensitizes AR to residual post-castration androgen, drives AR nuclear activity under androgen-poor conditions, and confers enzalutamide resistance. Conversely, PSMA2 silencing stabilizes HSP90, desensitizes CRPC to androgen, and re-sensitizes resistant cells to enzalutamide-induced cell death. Importantly, PSMA2 also promotes lineage plasticity: treatment-induced PSMA2 enhances transcriptional and phenotypic conversion toward tNEPC. Thus, we uncover a single stress-induced node (PSMA2) that both maintains AR-dependent survival under ADT and fuels the neuroendocrine transition. PSMA2 marks an AR-hypersensitized transitional state and is itself a therapeutically actionable driver of tNEPC evolution, revealing an opportunity for rational interception of the lethal ADT-CRPC-tNEPC trajectory.