Stem-like Prostate Remodeling in Obesity Mediates Resistance to 5α-Reductase Inhibition Therapy in BPH

Benign prostatic hyperplasia (BPH) is closely associated with obesity and metabolic syndrome. Although 5-reductase inhibitors (5ARIs) are widely used to treat BPH, their effectiveness varies significantly, particularly in obese patients. However, the mechanisms by which obesity affects prostate growth and modulates therapeutic responses remain poorly understood. In mice, highfat diet (HFD) increased prostate weight and induced SRD5A2-independent epithelial remodeling with expansion of proximal urethral luminal epithelial cells. ScRNA-seq of prostate tissues from Srd5a2null and control mice on HFD showed enrichment of proximal stem-like populations, reduced androgen signaling, and activation of WNT and NOTCH pathways via heightened stromal-epithelial crosstalk. Clinically, BMI gain, regardless of 5ARI use, correlated with transition zone growth, stronger activity of stem-cell signatures, reduced SRD5A2, and androgen signaling downregulation. Xenium spatial profiling indicated that BMI gain expands stem-like epithelial populations and a NOTCHenriched periepithelial stromal niche surrounding epithelial compartments, supporting stemness. Patients with substantial BMI gain were less responsive to 5ARI, whereas weight control plus 5ARI therapy synergistically improved outcomes. In conclusion, BMI gain promotes proximal prostate enlargement through an SRD5A2-independent stem-like cell mediated pathway that blunts 5ARI efficacy. Combining pharmacotherapy with weight control yields superior efficacy and supports individualized management of BPH.