Enzalutamide-Resistant STEAP4(+) MyoCAF Secrete Phosphatidylcholine to Foster Progression by Activating Stemness in Hormone-Sensitive Prostate Cancer.

Despite the expanding clinical application of second-generation anti-androgens like enzalutamide (ENZ) in hormone-sensitive prostate cancer (HSPC), therapeutic resistance culminating in castration-resistant prostate cancer (CRPC) persists as an unresolved clinical crisis. Through comprehensive single-cell transcriptomic profiling of ENZ-naïve and ENZ-treated tumors, an expansion of ENZ-resistant myofibroblastic cancer-associated fibroblast (designated STEAP4(+) myoCAF) is identified that correlates with adverse clinical outcomes. Strikingly, STEAP4(+) myoCAF demonstrated intrinsic ENZ resistance through a mechanistically novel pathway involving transcription factor binding to IGHM enhancer 3 (TFE3)-mediated autophagy activation. Integrated lipidomic and functional analyses revealed that TFE3 activation drives phosphatidylcholine overproduction via direct upregulation of phosphate cytidylyltransferase 1A (PCYT1A), establishing a tumor-promoting feedforward loop. The resultant phospholipid-rich microenvironment activates an HSP90/HIF1A signaling axis in malignant epithelial cells, fueling cancer stemness and therapeutic escape. These findings position the STEAP4(+) myoCAF-TFE3/tumor-HIF1A axis as a master regulator of anti-androgen resistance, offering clinically actionable targets to extend treatment efficacy in advanced prostate cancer.