Aromatase in endometriosis and uterine leiomyomata.

Endometrial tissue from uterine disease-free women does not exhibit aromatase activity. In contrast, aromatase enzyme activity and mRNA levels are readily detectable in endometriosis. PGE2 stimulates both aromatase expression and activity in endometriotic stromal cells via promoter II region of the aromatase gene. This results in local production of estradiol, which induces PGE2 formation and establishes a positive feedback cycle. This mechanism seems to contribute to continuous production of estradiol and PGE2. Aromatase mRNA levels and enzyme activity are also present in uterine leiomyomata that are estrogen-dependent benign tumors of the myometrium. Successful treatment of endometriosis and uterine leiomyomata using aromatase inhibitors by recent pilot trials underscores the clinical significance of these molecular studies.