title: Calbindin-D9k as a sensitive molecular biomarker for evaluating the             synergistic impact of estrogenic chemicals on GH3 rat pituitary cells.
abstract: Various endocrine-disrupting chemicals (EDCs) such as bisphenol A (BPA), alkylphenols [4-nonylphenol (NP) and 4-tert octylphenol (OP)] and isobutylparaben (IBP) are a constant concern due to their widespread distribution. It has been reported that some combinations of hormone-disrupting chemicals are much more powerful than any of the chemicals alone. In this study, we measured the expression of an estrogenic biomarker gene, calbindin-D9k (CaBP-9k), and progesterone receptor (PR) to evaluate the individual or combined estrogenic activity of BPA, NP, OP and IBP in GH3 rat pituitary cells. Most doses of the individual compounds and all the doses of the combined chemicals significantly increased CaBP-9k and PR mRNA and protein expression compared to the vehicle (except for PR expression after treatment with OP and NP at 10-7 M). Of note, high doses (10-6 and 10-5 M) of the EDC combinations increased the translational and transcriptional levels of CaBP-9k by 1.3- to 2.4-fold compared to each individual equivalent concentrations of EDCs. To determine whether the increased CaBP-9k gene expression was induced via intracellular estrogen receptor (ER), we blocked ER signaling using fulvestrant, an ER antagonist. The results showed that fulvestrant significantly reversed the CaBP-9k and PR upregulation following treatment with individual EDCs or their combinations. Taken together, we conclude that combinations of BPA, NP, OP and IBP in GH3 rat pituitary cells have synergistic estrogenic activities mediated by ER signaling. In addition, the expression of the CaBP-9k gene may be used as a biomarker to assess the synergistic effects of EDCs in vitro.
authors.affiliation: Laboratory of Veterinary Biochemistry and Molecular Biology,                     College of Veterinary Medicine, Chungbuk National University, Cheongju,                     Chungbuk, Republic of Korea.
authors.forename: Thuy T B
authors.initials: TT
authors.lastname: Vo
authors.forename: Beum-Soo
authors.initials: BS
authors.lastname: An
authors.forename: Hyun
authors.initials: H
authors.lastname: Yang
authors.forename: Eui-Man
authors.initials: EM
authors.lastname: Jung
authors.forename: Inho
authors.initials: I
authors.lastname: Hwang
authors.forename: Eui-Bae
authors.initials: EB
authors.lastname: Jeung
mesh_terms: D000818:Animals; D001559:Benzhydryl Compounds / Q000494:pharmacology; D015415:Biomarkers / Q000378:metabolism; D064026:Calbindins; D002460:Cell Line; D004357:Drug Synergism; D052244:Endocrine Disruptors / Q000494:pharmacology*; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism; D004967:Estrogens / Q000494:pharmacology*; D000077267:Fulvestrant; D015870:Gene Expression / Q000187:drug effects; D010226:Parabens / Q000494:pharmacology; D010636:Phenols / Q000494:pharmacology; D010902:Pituitary Gland / Q000166:cytology; D051381:Rats; D011980:Receptors, Progesterone / Q000235:genetics / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000235:genetics / Q000378:metabolism*; D000098826:Bisphenol A Compounds
chemical_list: D001559:Benzhydryl Compounds; D015415:Biomarkers; D064026:Calbindins; D052244:Endocrine Disruptors; D004958:Estradiol; D004965:Estrogen Antagonists; D047628:Estrogen Receptor alpha; D004967:Estrogens; D000077267:Fulvestrant; D010226:Parabens; D010636:Phenols; D011980:Receptors, Progesterone; D064030:S100 Calcium Binding Protein G; C506487:ESR1 protein, human; C576506:S100G protein, human; C576508:S100g protein, rat; C474055:octylphenol; C471067:isobutylparaben; C041594:4-nonylphenol; C006780:bisphenol A; D000098826:Bisphenol A Compounds