Protein Expression of Estrogen Receptors α and β and Aromatase in Myometrium and Uterine Leiomyoma

Background: Leiomyomas are the most common tumors of the female reproductive tract and a major public health problem. The mechanism of tumorigenesis is unknown, but evidence suggests that estrogens regulate cell proliferation and myoma growth. This effect might be due to different amounts of estrogen receptors (ER alpha and ER beta) in normal and myoma tissues and overexpression of aromatase P450 in myomas. Purpose: To assess protein expression of ERs and aromatase in leiomyomas and normal adjacent myometrium of premenopausal women. Methods: Samples were collected from 12 premenopausal women admitted for abdominal hysterectomy due to fibroids. Results: The protein expression of ER alpha, ER beta and aromatase was similar in leiomyoma and normal myometrium (p = 0.239, p = 0.695 and p = 0.203, respectively). Conclusions: In this analysis of 12 matched leiomyoma and myometrial samples, the data do not support the theory that overexpression ER alpha, ER beta and aromatase in uterine leiomyomas compared to adjacent myometrium are the cause of tumor growth. The estrogens may exert their growth-stimulatory effects on leiomyomas intermediated by other elements, such as cytokines and growth or apoptosis factors. The effect of estrogen on the growth and development of fibroids is complex and far from being completely understood. Copyright (C) 2012 S. Karger AG, Basel