RESEARCH ARTICLE Novel Promising Estrogenic Receptor Modulators: Cytotoxic and Estrogenic Activity

The cytotoxicity of 27 benzanilides and dithiobenzanilides built on a stilbene scaffold and possessing various functional groups in aromatic rings previously described for their spas-molytic properties was assayed on three human cancer cell lines (A549 –lung adenocarci-noma, MCF-7 estrogen dependent breast adenocarcinoma and MDA-MB-231 estrogen independent breast adenocarcinoma) and 2 non-tumorigenic cell lines (CCD39Lu–lung fibroblasts, MCF-12A- breast epithelial). Three compounds (6, 15 and 18) showed selective antiproliferative activity against estrogen dependent MCF-7 cancer cells and their estro-genic activity was further confirmed in MCF-7 transfected with an estrogen receptor reporter plasmid and in HEK239 cells over-expressing the estrogen receptor alpha (ERα). Com-pound 18 is especially interesting as a potential candidate for therapy since it is highly toxic and selective towards estrogen dependent MCF7 cell lines (IC50 = 5.07 μM versus more than 100 μM for MDA-MB-231) and almost innocuous for normal breast cells (IC50 = 91.46 μM for MCF-12A). Docking studies have shown that compound 18 interacts with the receptor in the same cavity as estradiol although the extra aromatic ring is involved in addi-tional binding interactions with residue W383. The role of W383 and the extended binding mode were confirmed by site-directed mutagenesis