[Study on the local estrogen biosynthesis in human uterine leiomyoma]

The growth of uterine leiomyoma is regulated not only by the estrogen levels in blood, but also by estrogen production in the tumor itself. In this study, we investigated both the estrone formation (estrone sulfatase activity) and the transformation from estrone to estrone sulfate (estrone sulfotransferase activity) in human leiomyoma tissue. We compared them with those in the myometrium and endometrial tissues overlying and opposite a uterine leiomyoma node. We also measured the tissue concentrations of estrone, estradiol and estrone sulfate. Estrone sulfatase activity in the uterine leiomyoma was 0.49 +/- 0.08 nmol/h/mg protein (Mean +/- SE), and was lower than that in the myometrial tissue (0.76 +/- 0.09). Moreover, the enzyme activity was higher in the endometrium overlying the leiomyoma node (2.62 +/- 0.29) than in the endometrium opposite to it (2.10 +/- 0.24). On the other hand, estrone sulfotransferase activity in the myoma (20.2 +/- 2.4 pmol/h/mg protein) was higher than in myometrial tissue (16.7 +/- 2.3). The concentrations of estrone and estradiol in leiomyoma tissue were lower than in the tissues surrounding the leiomyoma. The tissue concentration of estrone sulfate was higher in leiomyoma tissues. These results suggest that estrone sulfate is hydrolyzed mainly by estrone sulfatase in the endometrium and myometrium surrounding leiomyoma nodes and the estrone formed may affect the growth of leiomyoma.