Vitamin D deficiency alters prostate epithelial differentiation and increases prostate cancer aggressiveness in ex vivo and in vivo models.

Here, we examined the consequences of biologically relevant vitamin D deficiency, a known risk factor for aggressive prostate cancer, using ex vivo and in vivo models. Phenotypic and single-cell RNA sequencing of mouse prostate organoids showed that vitamin D deficiency stunted luminal cell differentiation more than androgen deficiency, which is a known driver of prostate development. Mice fed a vitamin D-deficient diet showed significantly altered expression of androgen-responsive genes in their prostate luminal cells, as determined by single-cell RNA sequencing. MDA-PCa-2b and 22Rv1 human prostate cancer cells, when maintained for 6 months in 1,25-dihydroxyvitamin D, had very different responses compared to short-term treatments. Notably, the MDA-PCa-2b cells lost the ability to form xenografts, despite normal proliferation in vitro. RNA sequencing showed that these cells also had disruptions in androgen signaling and in multiple cancer-related pathways, which differed by treatment duration. This study offers new insights and validation of vitamin D's role in both benign and malignant prostate biology, underscoring its essential hormonal functions and supporting strategies for vitamin D supplementation to reduce prostate cancer risk in vulnerable populations.