Estrogen receptor independent rapid non-genomic effects of environmental estrogens on [Ca2+]i in human breast cancer cells.

The aim of this study was to identify and characterize an alternative pathway through which environmental estrogenic compounds may mediate their intracellular effects. Three human breast cancer cell lines were employed including MCF-7 cells, which express both ERalpha and ERbeta; MDA-MB-231 cells, which express ERbeta but not ERalpha; and SKBR-3 cells, which express neither ERalpha nor ERbeta. The effect of environmental estrogenic compounds on intracellular calcium ion concentration (Ca(2+)) was measured and compared to that of 17beta-estradiol (E2). A rapid and maintained increase in Ca(2+) was observed following the application of nanomolar concentrations of environmental estrogens and E2 regardless of the expression of ERalpha and ERbeta. Removal of extracellular Ca(2+) completely abolished the steroid-induced Ca(2+) increase. Pre-treatment of cells with the estrogen receptor (ER) antagonist ICI 182,780 had no effect on either basal Ca(2+) or the steroid-triggered Ca(2+) response. In summary, we have demonstrated ER independent rapid non-genomic effects of environmental estrogenic compounds, at nanomolar concentrations, on Ca(2+). The results of this study demonstrate an alternative pathway to explain potent intracellular effects of endocrine disrupting chemicals.