Immunohistochemical evidence of the existence and localization of aromatase in human prostatic tissues

Estrogens may be involved in normal growth of the prostate and the development of benign prostatic hyperplasia (BPH). The location of estrogen production is still unclear, and there has never been a direct evidence for the existence of the aromatase system, which converts androgens to estrogens, in the prostate. Using an avidin-biotin technique with a polyclonal anti-human placental aromatase, we demonstrated the existence of aromatase in normal prostates of young men and BPH tissue from elderly men. The staining is more pronounced in the stroma. However, positive stains were also seen in the glandular epithelium. While evidence of the existence of an enzyme system does not equal demonstration of its activity in a specific tissue site, our findings suggest that local estrogen production in the stroma and/or epithelium of the prostate may play a role in the maintenance of normal growth and development of BPH.