ABSTRACT
BACKGROUND: Benign prostatic hyperplasia (BPH) is the most common benign tumor in older men; the etiology of this disease remains poorly understood. Testosterone and dihydrotestosterone (DHT) both act as androgen via a single androgen receptor. Testosterone is converted to DHT by 5alpha-reductase in prostatic stromal cells. Progesterone has been reported to inhibit DHT conversion; howevwe, its effect on prostatic stromal cells remains to be elucidated. MATERILAS AND METHODS: In this experiment, we investigated the effect of progesterone on androgen receptor expression induced by DHT. We also tested the effect of progesterone on cyclooxygenase-2 (COX-2) expression, as well as prostate stromal cell proliferation using the cell count kit-8. RESULTS: Progesterone did not cause an increase of prostate stromal cell proliferation. The mRNA expression of the androgen receptor and COX-2 were not changed by progesterone; the expressions of androgen receptor and COX-2 proteins were decreased by progesterone in prostate stromal cells. CONCLUSION: These results suggest that in prostate stromal cells, progesterone decreases androgen receptor protein expression, which results in decrement of COX-2 protein expression. This effect might be mediated by post-transcriptional regulation.