Hormone dependency and the action of tamoxifen in human mammary carcinoma cells.
Conditions are described which allow to demonstrate estradiol dependency of proliferation in MCF-7 human mammary carcinoma cells in a reproducible manner. Our results concerning the action of Tamoxifen on the growth of MCF-7 cells differ in two aspects from previous reports: (a) The inhibitory effect of pharmacological doses (10(-7) M) is only obvious if the cells are stimulated by estradiol. (b) In the absence of estradiol, Tamoxifen acts as a weak estrogenic agonist, by stimulating the growth of MCF-7 cells. This finding could imply that premenopausal women should not be treated with Tamoxifen after ovariectomy.
D001943:Breast Neoplasms / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D009376:Neoplasms, Hormone-Dependent / Q000473:pathology*; D013629:Tamoxifen / Q000494:pharmacology*
D013629:Tamoxifen; D004958:Estradiol