Effects of environmental estrogens on tumor necrosis factor alpha-mediatedapoptosis in MCF-7 cells

Environmental estrogens represent a class of compounds which have been show n to mimic the effects or activity of the naturally occurring ovarian hormo ne 17 beta-estradiol, Given the role of 17 beta-estradiol in cell survival in a number of systems, we wished to determine if environmental estrogens p rotect MCF-7 cells from apoptosis, Here we demonstrate that the organochlor ine pesticides o,p' DDT and alachlor, like 17 beta-estradiol, have the abil ity to suppress tumor necrosis factor alpha (TNF)-induced apoptosis in estr ogen receptor (ER)-positive MCF-7 breast carcinoma cells. These compounds, however, did not affect TNF-induced apoptosis of the ER-negative MDA-MB-231 cell line, The ability of these compounds to suppress apoptosis in MCF-7 c ells was correlated with an ER-dependent increase in Bcl-2 expression. Take n together these results demonstrate that estrogenic organochlorine pestici des like o,p' DDT and alachlor may partially mimic the primary endogenous e strogen, 17 beta-estradiol, and function to suppress apoptosis in ER-respon sive cells.