Testosterone effect on immature prostate gland growth in dogs associated with suppression of TGF-beta mRNA expression
B Al-Trad, R Al-Omari & F Shidaifat
The aim of this study was to evaluate the effect of testosterone treatment on the pattern of prostate cells proliferation and differentiation and their correlation with transforming growth factor-beta expression. Prostate gland development was compared in intact immature dogs with testosterone treated immature dogs for one month. Proliferation and differentiation pattern of prostatic cells were assessed by histological and immunohistological localization of proliferating cell nuclear antigen (PCNA), vimentin, and α-actin. Testosterone treatment resulted in a 10 fold increase in prostate gland weight with a typical organization of the gland into a structure similar to that observed in mature dogs. The narrow acini which contain flat basal cells of immature gland changed to a tubuloacinar structures that contain tall columnar secretory cells and less abundant flattened basal cells. The fibromuscular compartments showed an increase in the muscular component as evidenced by the high reactivity to α-actin with no remarkable changes in the vimentin expression. This effect of testosterone treatment on the prostate gland development was associated with a significant reduction in the proliferation capacity of stromal cell with no noticeable changes in the proliferation pattern of epithelial cells as those cells continued to be the predominantly proliferating cells in both treated and untreated dogs. These changes in the prostate associated with a two fold decrease in TGF-beta mRNA expression as assessed by the Real time PCR. However, the immunolocalization of TGF-beta was shifted slightly from epithelial cells which predominantly express TGF-beta in untreated animals to the stromal compartment of treated animals. Based on these results it appears that androgen acts to drive the differentiation of prostate cells and instruct their organization into a matured-like structure of the gland. The androgen regulation of the prostate gland appears to involve the regulation of TGF-beta gene expression.