In the last decades, substances with estrogenic activity have been dispersed into the environment. Xenoestrogens act by binding to estrogen receptors, ligand-regulated transcription factors, for which two subtypes have been described, ER-α and ER-β, which are often coexpressed at variable amounts in different tissues. We investigated variations in the expression of ER-α and ER-β mRNAs following treatment with four xenoestrogens (bisphenol A, 4-tert octylphenol, 2-hydroxybiphenyl, 4-hydroxybiphenyl) and with 17β-estradiol in estrogen-sensitive (T47D) and estrogen-insensitive (BT20) breast cancer cell lines. Although to a variable extent, both estradiol and the tested xenoestrogens increased the expression of ER-β mRNA, whereas a slight effect on ER-α was observed only in T47D cells. Upregulation of ER-β expression by estradiol and xenoestrogens was observed only in the presence of detectable ER-α protein levels. These findings indicate a regulatory role for ER-β in ER-α-mediated transcription and a role for ER-β in mediating xenoestrogen toxicity.
- Breast cancer
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology