2002 Volume 49 Issue 4 Pages 465-471
Bisphenol A (BPA), a monomer of plastic used in consumer products, is abundant in the environment and enters the body by ingestion or adsorption. In order to characterize the estrogenic effect of BPA, we performed luciferase assay on three independent cell lines derived from different tissues transfected with either human ERα cDNA or ERβ cDNA. The estrogenic activities of BPA were detectable in all cell lines via both ERα and ERβ. In 293T cells and Hec-1 cells, the estrogenic activities were significantly decreased when cells expressing ERα were incubated with 10-6 M BPA in the presence of 10-8 M 17β-estradiol (E2) while the activities via ERβ were essentially unchanged in the same conditions. Interestingly, no reduction of estrogenic activity was detected in HOS-TE85 cells via either ERα or ERβ. Our results indicate that BPA only acts as an agonist of estrogen via ERβ whereas it has dual actions as an agonist and antagonist in some types of cells via ERα. Thus, the activity of BPA may depend on the ER subtype and the tissue involved.