Spatial localization and pharmacodynamic assessment of intracrine androgen metabolism in CRPC xenograft tumor tissues upon active vitamin D treatment.

Castrate-resistant prostate cancer (CRPC) progression is driven by intracrine androgen synthesis despite low circulating androgens. This study investigates the effects of active vitamin D (1,25-(OH)₂-D₃) on intracrine steroidogenesis in LNCaP xenograft tumors. Using mass spectrometry imaging, quantitative LC-MS/MS, and gene expression analyses, we demonstrate that vitamin D modulates androgen metabolism, reducing levels of potent androgen receptor ligands such as testosterone and dihydrotestosterone, while increasing hydroxylated androgen metabolites. Vitamin D treatment also suppresses AR-regulated gene expression and slows tumor growth compared to androgen precursor (DHEA) administration alone. Mass spectrometry imaging revealed widespread intracrine androgen production without distinct spatial localization within tumors at the image resolution analyzed. These findings suggest vitamin D disrupts androgen receptor signaling by altering intracrine androgen biosynthesis, supporting its potential as an adjunct therapy in CRPC management.