There is evidence that
estrogens can directly modulate human prostate cell activity. It has also been shown that cultured human
prostate cancer LNCaP can synthesize the active
estrogen estradiol (E2). To elucidate the metabolism of
estrogens in the human prostate, we have studied the expression of
enzymes involved in the formation and inactivation of
estrogens at the cellular level.
17beta-Hydroxysteroid dehydrogenase (17beta-HSD) types 1, 2, 4, 7, and 12, as well as
aromatase mRNA and
protein expressions, were studied in
benign prostatic hyperplasia (BPH) specimens using in situ hybridization and immunohistochemistry. For 17beta-HSD type 4, only in situ hybridization studies were performed. Identical results were obtained with in situ hybridization and immunohistochemistry. All the
enzymes studied were shown to be expressed in both epithelial and stromal cells, with the exception of 17beta-HSD types 4 and 7, which were detected only in the epithelial cells. On the basis of our previous results, showing that 3beta-HSD and 17beta-HSD type 5 are expressed in human prostate, and of the present data, it can be concluded that the human prostate expresses all the
enzymes involved in the conversion of circulating
dehydroepiandrosterone (
DHEA) to E2. The local biosynthesis of E2 might be involved in the development and/or progression of prostate pathology such as BPH and
prostate cancer through modulation of
estrogen receptors, which are also expressed in epithelial and stromal cells.