title: The food contaminants bisphenol A and 4-nonylphenol act as agonists for estrogen receptor alpha in MCF7 breast cancer cells.
abstract: Xenoestrogens are chemically distinct industrial products potentially able to disrupt the endocrine system by mimicking the action of endogenous steroid hormones. Among such compounds, the ubiquitous environmental contaminants bisphenol A (BPA) and 4-nonylphenol (NPH) may promote adverse effects in humans triggering estrogenic signals in target tissues. Following a research program on human exposure to endocrine disruptors, we found contamination of fresh food by BPA and NPH. More important, these contaminants were found to display estrogen-like activity using as a model system the estrogen-dependent MCF7 breast cancer cells (MCF7wt); its variant named MCF7SH, which is hormone-independent but still ERalpha-positive, and the steroid receptor-negative human cervical carcinoma HeLa cells. In transfection experiments BPA and NPH activated in a direct manner the endogenous ERalpha in MCF7wt and MCF7SH cells, as the antiestrogen hydroxytamoxifen was able to reverse both responses. Moreover, only the hormone-binding domains of ERalpha and ERbeta expressed by chimeric proteins in HeLa cells were sufficient to elicit the transcriptional activity upon BPA and NPH treatments. Transfecting the same cell line with ERalpha mutants, both contaminants triggered an estrogen-like response. These transactivation properties were interestingly supported in MCF7wt cells by the autoregulation of ERalpha which was assessed by RT-PCR for the mRNA evaluation and by immunoblotting and immunocytochemistry for the determination of protein levels. The ability of BPA and NPH to modulate gene expression was further confirmed by the upregulation of an estrogen target gene like pS2. As a biological counterpart, concentrations of xenoestrogens eliciting transcriptional activity were able to stimulate the proliferation of MCF7wt and MCFSH cells. Only NPH at a dose likely too high to be of any physiological relevance induced a severe cytotoxicity in an ERalpha-independent manner as ascertained in HeLa cells. The estrogenic effects of such industrial agents together with an increasing widespread human exposure should be taken into account for the potential influence also on hormone-dependent breast cancer disease.
authors.affiliation: Department of Pharmaco-Biology, University of Calabria, 87036 Rende (CS), Italy.
authors.forename: Adele
authors.initials: A
authors.lastname: Vivacqua
authors.forename: Anna Grazia
authors.initials: AG
authors.lastname: Recchia
authors.forename: Giovanna
authors.initials: G
authors.lastname: Fasanella
authors.forename: Sabrina
authors.initials: S
authors.lastname: Gabriele
authors.forename: Amalia
authors.initials: A
authors.lastname: Carpino
authors.forename: Vittoria
authors.initials: V
authors.lastname: Rago
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Di Gioia
authors.forename: Antonella
authors.initials: A
authors.lastname: Leggio
authors.forename: Daniela
authors.initials: D
authors.lastname: Bonofiglio
authors.forename: Angelo
authors.initials: A
authors.lastname: Liguori
authors.forename: Marcello
authors.initials: M
authors.lastname: Maggiolini
mesh_terms: D001559:Benzhydryl Compounds; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D004785:Environmental Pollutants / Q000494:pharmacology*; D047628:Estrogen Receptor alpha; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology; D005260:Female; D005506:Food Contamination; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D009376:Neoplasms, Hormone-Dependent / Q000235:genetics / Q000378:metabolism; D010636:Phenols / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011960:Receptors, Estrogen / Q000819:agonists* / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation / Q000187:drug effects; D014162:Transfection; D000098826:Bisphenol A Compounds
chemical_list: D001559:Benzhydryl Compounds; D004785:Environmental Pollutants; D047628:Estrogen Receptor alpha; D004968:Estrogens, Non-Steroidal; D010636:Phenols; D012333:RNA, Messenger; D011960:Receptors, Estrogen; C041594:4-nonylphenol; C006780:bisphenol A; D000098826:Bisphenol A Compounds