The combination of 17-Estradiol and Bisphenol A weaken their respective action

17-Estradiol (E2) and Bisphenol A (BPA) are important endocrine disrupting chemicals (EDCs). In this work, cell proliferation assay using cell cycle analysis method and determination of estrogen receptor a protein was used to investigated the mechanism and effects respectively and in mixture of the two EDCs in stimulating the growth of human breast cancer MCF-7 cell When the concentration of E2 and BPA were 10^-12mol/L and 10^-8mol/L respectively, E2 and BPA could reduce the express of ERα protein by activated ERa pathway, accelerated the cell cycle, decreased the percentages of cells in G0/1 phase, increased the percentages of cells in S phase at 48 h, and thus promoted the cancer cell growth. However, the combination effect of these two compounds did not induce the growth of cancer cell and the mixture reduced the ratio in S phase compared with E2 or BPA alone, which lead to weakening of the proliferation ability. There was a significant interaction between BPA and E2 and such a weakening effect had not been reported before.