| Research Abstract |
In this study, estrogenicity of bisphenol A and phytoestrogens such as genistein was compared in human breast cancer MCF-7 cells using so called E-screen assay. We also established induction of expression of pS2 gene, an estrogen-resposive gene, after exposure of MCF-7 cells to chemicals with estrogenicity. Estrogenic activities of daidzein, naringenin, kaempfenol were weaker than that of genistein. For detoxification pathway of estrogenic compounds, sulfoconjugation of bisphenol A and phytoestrogens was catalyzed by human hepatic microsomes. On the basis of Km values, affinity of bisphenol A to sulfotransferase seemed to be higher than that of phytoestrogens. A form of thermostable phenol-sulfating sulfotransferase, ST1A3, was identified as a bisphenol A-sulfating sulfotransferase.
Difference in the mechanisms of estrogenicity between phytoestrogens and bisphenol A was not, however, achieved. It would be possible by analyses of gene expression after exposure of MCF-7 cells to phytoestrogens, and bisphenol A whose toxic action is suspected due to its estrogenic action.
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