Antiestrogenic action of 3-hydroxytamoxifen in the human breast cancer cell line MCF-7
Roos, W.; Oeze, L.; Löser, R.; Eppenberger, U.
Journal of the National Cancer Institute 71(1): 55-59
1983
ISSN/ISBN: 0027-8874 PMID: 6575210 Document Number: 207171
The antiestrogenic action of 3-hydroxytamoxifen [trans-1-(4-beta-dimethylaminoethoxyphenyl)-1-(3-hydroxyphenyl)-2 -phenylbut-1-ene] was characterized in vitro and compared with that of tamoxifen [trans-1-(4-beta-dimethylaminoethoxyphenyl)-1,2-diphenylbut-1-ene]. The relative binding affinities of 3-hydroxytamoxifen to estrogen receptor were 3.3% in cytosol of MCF-7 cells and 1.5% in human mammary carcinoma cytosol compared to values of 0.2 and 0.3% for tamoxifen (the affinity of 17 beta-estradiol considered to be 100%). The concentration of 3-hydroxytamoxifen necessary to suppress the 17 beta-estradiol-induced growth stimulation of MCF-7 cells was about tenfold lower than that for tamoxifen. The induction of progesterone receptor in MCF-7 cells by 17 beta-estradiol was inhibited by 3-hydroxytamoxifen. In the absence of 17 beta-estradiol, 3-hydroxytamoxifen gave rise to a moderate increase in the progesterone receptor levels, which demonstrates the partially estrogenic character of hydroxytamoxifen.