The Action Mechanism of Tamoxifen Via Estrogen Receptor on Uterine Leimyoma

Lee, Byung Seok; Cha, Dong Hyun; Jung, Kyung Ah; Lee, Hye Dae; Park, Ki Hyun; Cho, Dong Jae; Song, Chan Ho

Abstract

OBJECTIVES
To investigate the distribution of ERa, ERb, c-fos and c-jun in the uterine myoma and myometrium in oder to know how the tamoxifen cause the growth of myoma.
METHODS
Myoma and myometrial tissue were obtained from the postmenopausal women treated with tamoxifen in the patients with breast cancer and in the premenopausal patients, who were undergoing myoma of uterus from 1998 through 2000. The espression of each gene was quantitated with quantitative RT-PCR.
RESULTS
The expression of ERa was slightly increased in the myoma than the myometrium in the proliferative phase, and was slightly decreased in the myometrium than the myoma in the secretory phase. However it was not significant statistically. In the postmemopausal women treated with tamoxifen, ERa was expressed in all myoma and myometrial tissues and the expression was not statistically significant. The expression of ERb was slightly increased in the myometrium than the leiomyoma in the proliferative and secretory phase, but it was not significant statistically. In the postmemopausal women treated with tamoxifen, the expression of ERb was significantly incresed in the myometrium than the leiomyoma. The expression of c-fos was significantly increased in the myometrium than the leiomyoma in the proliferative and secretory phase. In the postmemopausal women treated with tamoxifen, the expression of c-fos was slightly increased in the leiomyoma than the myometrium, however, it was not statistically significant.
CONCLUSION
Tamoxifen may cause the growth of leiomyoma by ERa with AP-1 pathway reducing the counteraction of ERb to ERa.