Laboratory of Veterinary Biochemistry and Molecular Biology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk 361-763, Republic of Korea.
Int J Mol Med. 2012 Feb;29(2):294-302. doi: 10.3892/ijmm.2011.823. Epub 2011 Nov 7.
Endocrine disruptors (EDs) have estrogenic activity and can cause physiological estrogenic responses. Octylphenol (OP) is one of the alkylphenolic compounds known as environmental xenoestrogens because they strongly compete with endogenous estrogens to bind to estrogen receptors (ERs). Isobutyl paraben (IBP), a widely used preservative, also exhibits estrogenic activity. Calbindin-D₉k (CaBP-9k) is a novel biomarker for the detection of EDs used in our previous studies. In this study, the CaBP-9k gene was utilized as a marker for the estrogenic activity of combined OP and IBP to investigate possible additive, synergistic or antagonistic effects of these compounds in GH3 rat pituitary cells. GH3 cells were treated with different individual or combined doses of OP and IBP. In addition, the antiestrogen ICI 182,780 was used to examine the potential involvement of ERs in the induction of CaBP-9k expression by EDs. It was found that CaBP-9k expression was significantly increased at a high-dose of OP (1 µM) combined with each dose of IBP (0.1, 1 or 10 µM) compared to all single doses of IBP and OP. A synergistic increase in luciferase activity and CaBP-9k expression was observed following combination treatment with OP and IBP. Expression of the progesterone receptor (PR) gene was similarly induced by combined treatment with OP and IBP. In addition, pre-treatment with ICI 182,780, an estrogen antagonist, significantly blunted ED-induced CaBP-9k and PR expression. In summary, the expression of CaBP-9k and PR was induced more potently by combined OP and IBP than by treatment with either ED alone. ICI 182,780 treatment reversed ED-induced CaBP-9k and PR expression in these cells. Taken together, these results indicate that combined exposure to OP and IBP has a synergistic effect on the induction of CaBP-9k and PR gene expression via an ER-dependent pathway in GH3 cells.
内分泌干扰物（EDs）具有雌激素活性，可引起生理性雌激素反应。辛基酚（OP）是一种烷基酚化合物，因其与内源性雌激素强烈竞争结合雌激素受体（ER）而被称为环境雌激素。作为一种广泛使用的防腐剂，异丁基对羟苯甲酸酯（IBP）也具有雌激素活性。钙结合蛋白-9k（CaBP-9k）是我们之前研究中用于检测 EDs 的新型生物标志物。在这项研究中，我们利用 CaBP-9k 基因作为标记物，研究 OP 和 IBP 联合作用对 GH3 大鼠垂体细胞中 ED 类雌激素活性的影响，以探讨这些化合物可能存在的相加、协同或拮抗作用。用不同剂量的 OP 和 IBP 单独或联合处理 GH3 细胞。此外，还使用了抗雌激素 ICI 182,780 来检测 ER 参与 ED 诱导 CaBP-9k 表达的潜在作用。结果发现，与所有单独剂量的 IBP 和 OP 相比，高剂量 OP（1 μM）与每个剂量的 IBP（0.1、1 或 10 μM）联合处理时，CaBP-9k 表达显著增加。OP 和 IBP 联合处理时观察到荧光素酶活性和 CaBP-9k 表达协同增加。孕激素受体（PR）基因的表达也同样受到 OP 和 IBP 联合处理的诱导。此外，用雌激素拮抗剂 ICI 182,780 预处理可显著减弱 ED 诱导的 CaBP-9k 和 PR 表达。综上所述，与单独使用任何一种 ED 相比，OP 和 IBP 联合处理更能强烈诱导 CaBP-9k 和 PR 的表达。ICI 182,780 处理逆转了这些细胞中 ED 诱导的 CaBP-9k 和 PR 表达。综上所述，这些结果表明，OP 和 IBP 联合暴露通过 ER 依赖性途径在 GH3 细胞中对 CaBP-9k 和 PR 基因表达具有协同诱导作用。
