The influence of antiestrogens on pS2 and cathepsin D mRNA induction in MCF-7 breast cancer cells.
Tamoxifen, although widely used in the treatment of estrogen-dependent tumors, is a partial estrogen agonist producing undesirable effects in breast cancer patients. ICI 182,780 a steroidal antiestrogen displays pure antagonist activity which is due to its ability to prevent dimerization of the estrogen receptor (ER). Our previous studies have shown that 1,1-dichloro-cis-2,3-diaryl cyclopropane (Analog II), a diarylcyclopropyl compound is devoid of estrogenic activity, has a weak binding affinity for the estrogen receptor in the mouse uterine tissue and inhibits the growth of breast cancer cells in culture. These findings suggest that Analog II may not inhibit tumor cell growth at the cellular level by an ER-mediated mechanism of action. Since these three antiestrogens appear to have different mechanisms of antiestrogenic activity, the purpose of this study was to compare the influence of the three antiestrogens on estradiol-induced expression of pS2 and cathepsin D (cath-D). These genes are known to be primarily under the influence of estrogen in ER positive MCF-7 human breast cancer cells. The results of this study demonstrate different mechanisms of regulation of the cath-D and pS2 genes by antiestrogens in MCF-7 cells. This study indicates that ICI 182,780 is a pure antagonist at the levels of gene regulation and cell proliferation. The relative order of inhibitory action was found to be ICI 182,780 > tamoxifen > Analog II.
Rajah
T T
TT
Department of Pharmacology and Toxicology, College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City 73190, USA.
Dunn
S T
ST
Pento
J T
JT
D001943:Breast Neoplasms / Q000378:metabolism*; D002402:Cathepsin D / Q000235:genetics / Q000378:metabolism*; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology*; D005260:Female; D000077267:Fulvestrant; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D011506:Proteins; D012333:RNA, Messenger / Q000378:metabolism*; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000494:pharmacology; D000071163:Trefoil Factor-1; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
D004965:Estrogen Antagonists; D009363:Neoplasm Proteins; D011506:Proteins; D012333:RNA, Messenger; C051838:TFF1 protein, human; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins; D013629:Tamoxifen; D000077267:Fulvestrant; D004958:Estradiol; C035174:tamoxifen analog II; D002402:Cathepsin D