Antiproliferative activity of a series of novel cyclopropyl antiestrogens on MCF-7 human breast cancer cells in culture.

The potential antitumor activity of a series of novel cyclopropyl compounds, which lack estrogen agonist activity, was evaluated in estrogen receptor positive human breast cancer cells (MCF-7) in culture. The compounds were evaluated to determine their antiproliferative activity at a concentration of 1 microM at 2, 4 and 6 days of treatment by hemocytometer using the Trypan Blue exclusion method to count viable cells. Estradiol-induced reversibility of the antiproliferative activity of these compounds was also evaluated. The activity of a series of 19 diaryl- and triarylcyclopropyl compounds was examined. Thirteen compounds inhibited the growth of MCF-7 cells while six were inactive. Five of the 13 active compounds produced antiproliferative activity which was reversed by 0.1 microM estradiol. Thus, several of these novel cyclopropyl compounds may be useful in the treatment of hormone-dependent breast cancer and other estrogen-dependent tumors.