Prostate epithelial-specific expression of activated PI3K drives stromal collagen production and accumulation.

We genetically engineered expression of an activated form of P110 alpha, the catalytic subunit of PI3K, in mouse prostate epithelium to create a mouse model of direct PI3K activation (Pbsn-cre4Prb;PI3KGOF/+ ). We hypothesized that direct activation would cause rapid neoplasia and cancer progression. Pbsn-cre4Prb;PI3KGOF/+ mice developed widespread prostate intraepithelial hyperplasia, but stromal invasion was limited and overall progression was slower than anticipated. However, the model produced profound and progressive stromal remodeling prior to explicit epithelial neoplasia. Increased stromal cellularity and inflammatory infiltrate were evident as early as 4 months of age and progressively increased through 12 months of age, the terminal endpoint of this study. Prostatic collagen density and phosphorylated SMAD2-positive prostatic stromal cells were expansive and accumulated with age, consistent with pro-fibrotic TGF-ß pathway activation. Few reported mouse models accumulate prostate-specific collagen to the degree observed in Pbsn-cre4Prb;PI3KGOF/+ . Our results indicate a signaling process beginning with prostatic epithelial PI3K and TGF-ß signaling that drives prostatic stromal hypertrophy and collagen accumulation. These mice afford a unique opportunity to explore molecular mechanisms of prostatic collagen accumulation that is relevant to cancer progression, metastasis, inflammation and urinary dysfunction. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

A temporal and spatial map of axons in developing mouse prostate.

Prostate autonomic and sensory axons control glandular growth, fluid secretion, and smooth muscle contraction and are remodeled during cancer and inflammation. Morphogenetic signaling pathways reawakened during disease progression may drive this axon remodeling. These pathways are linked to proliferative activities in prostate cancer and benign prostate hyperplasia. However, little is known about which developmental signaling pathways guide axon investment into prostate. The first step in defining these pathways is pinpointing when axon subtypes first appear in prostate. We accomplished this by immunohistochemically mapping three axon subtypes (noradrenergic, cholinergic, and peptidergic) during fetal, neonatal, and adult stages of mouse prostate development. We devised a method for peri-prostatic axon density quantification and tested whether innervation is uniform across the proximo-distal axis of dorsal and ventral adult mouse prostate. Many axons directly interact with or innervate neuroendocrine cells in other organs, so we examined whether sensory or autonomic axons innervate neuroendocrine cells in prostate. We first detected noradrenergic, cholinergic, and peptidergic axons in prostate at embryonic day (E) 14.5. Noradrenergic and cholinergic axon densities are uniform across the proximal-distal axis of adult mouse prostate while peptidergic axons are denser in the periurethral and proximal regions. Peptidergic and cholinergic axons are closely associated with prostate neuroendocrine cells whereas noradrenergic axons are not. These results provide a foundation for understanding mouse prostatic axon development and organization and, provide strategies for quantifying axons during progression of prostate disease.