Numerous studies have shown that widely used parabens possess estrogenic properties. In the present study, we examined the effects of methyl-, propyl- and butylparaben on the mRNA and protein expression of estrogen receptor (ER)-α (ESR1) and -β (ESR2) and the progesterone receptor (PGR). Human MCF-7 breast cancer cells and MCF-10A non-transformed breast epithelial cells were exposed to parabens at a concentration of 20nM; 17β-estradiol at a concentration of 10nM, was used as a positive control. Both propyl- and butylparaben stimulated PGR mRNA expression in MCF-7 cells, whereas methyl- and propylparaben PGR protein expression. In MCF-10A cells, butyl- and propylparaben increased only PGR mRNA expression. All parabens increased ESR1 gene and protein expression in MCF-7 and with the exception of butylparaben in MCF-10A cells. All parabens significantly increased ESR2 mRNA and protein expression in MCF-7 cells, but in MCF-10A cells only ESR2 protein expression. In summary, by virtue of their stimulatory action on the expression of ESR1, ESR2 and PGR in cancer cells, parabens can be viewed as potential contributors to breast cancer progression. Extension, the actions of these parabens on the expression of ERs and PGR in non-cancerous cells point to possible actions on breast cancer initiation.
Keywords: ERα; ERβ; Gene expression; PGR; Parabens; Protein expression.
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