Response of MCF-7 human breast cancer cells to some binary mixtures of oestrogenic compounds in-vitro.

The effects of simultaneous administration of some binary mixtures of seven natural and synthetic oestrogenic substances (17beta-estradiol, estrone, bisphenol A, butylbenzyl phthalate, endosulfan, methoxychlor and pentachlorophenol) on the cellular proliferation of human breast cancer MCF-7 cells in-vitro (a modified E-screen assay) have been measured. To assess the presence or absence of interactions of the two agents, the data were analysed on the basis of a graphical method in which the types and extents of interactions were described by response-surface diagrams. Of the nine combinations of the agents examined, synergistic interaction was evident for the combination of 17beta-estradiol and bisphenol A, whereas the remaining eight combinations were weakly synergistic, additive and/or weakly antagonistic in the dose-range tested.