Estrogen receptor (ER)-mediated activation by endocrine disrupting chemicals (EDCs)

Bisphenol AF as an Inducer of Estrogen Receptor β (ERβ): Evidence for Anti-estrogenic Effects at Higher Concentrations in Human Breast Cancer Cells

Bisphenols are endocrine disruptors that are widely found in the environment. Accumulating experimental evidence suggests an adverse interaction between bisphenols and estrogen signaling. Most studies have performed experiments that focused on estrogen receptor (ER) engagement by bisphenols. Therefore, the effects of bisphenols on the expression of ERα (ESR1) and ERβ (ESR2) remain largely unknown. In the present study, we examined the effects of four bisphenols: bisphenol A (BPA), bisphenol B (BPB), bisphenol S (BPS), and bisphenol AF (BPAF), on estrogen signaling in two human breast cancer cell lines (MCF-7 and SK-BR-3). Among these bisphenols, BPAF up-regulated the expression of ERβ, and this was coupled with the abrogation of estrogen response element (ERE)-mediated transcriptional activities as well as the down-regulation of Cdc2 expression in MCF-7 cells, without influencing the expression of ERα. BPAF functioned as an agonist of ERα at lower concentrations (nanomolar order), but did not exhibit any modulatory action on ERα transiently expressed in SK-BR-3 cells in the presence or absence of 17β-estradiol (E2) at higher concentrations (micromolar order). The introduction of ERβ cDNA resulted in greater reductions in MCF-7 cell viability than with BPAF alone. Since ERβ is a suppressive molecule of ERα function, these results provide rational evidence for BPAF functioning as an anti-estrogenic compound via the induction of ERβ at higher concentrations.

Chronic Exposure to Bisphenol A Reduces Successful Cardiac Remodeling After an Experimental Myocardial Infarction in Male C57bl/6n Mice

Estrogenic compounds such as bisphenol A (BPA) leach from plastics into food and beverage containers. Increased BPA exposure has been correlated with increased cardiovascular disease. To test the hypothesis that increased BPA exposure reduces cardiovascular remodeling, we chronically exposed C57bl/6n male mice to BPA and performed a myocardial infarction (MI). We measured cardiac function, as well as myeloid and cardiac fibroblast accumulation and activity. We found increased early death as well as increased cardiac dilation and reduced cardiac function in surviving BPA-exposed mice. Matrix metalloproteinase-2 (MMP2) protein and activity were increased 1.5-fold in BPA-exposed heart. BPA-exposed mice had similar neutrophil infiltration; however, monocyte and macrophage (MΦ) infiltration into the ischemic area was 5-fold greater than VEH mice potentially due to a 2-fold increase in monocyte chemoattractant protein-1. Monocyte and MΦ exposure to BPA in vitro in primary bone marrow cultures or in isolated peritoneal MΦ increased polarization to an activated MΦ, increased MMP2 and MMP9 expression 2-fold and activity 3-fold, and increased uptake of microspheres 3-fold. Cardiac fibroblasts (CF) differentiate to α-smooth muscle actin (αSMA) expressing myofibroblasts, migrate to the ischemic area and secrete collagen to strengthen the scar. Collagen and αSMA expression were reduced 50% in BPA-exposed hearts. Chronic in vivo or continuous in vitro BPA exposure ablated transforming growth factor beta-mediated differentiation of CF, reduced αSMA expression 50% and reduced migration 40% yet increased secreted MMP2 activity 2-fold. We conclude that chronic BPA exposure reduces the ability to successfully remodel after an MI by increasing MΦ-based inflammation and reducing myofibroblast repair function.