期刊
TOXICOLOGY
卷 176, 期 3, 页码 229-243出版社
ELSEVIER IRELAND LTD
DOI: 10.1016/S0300-483X(02)00162-2
关键词
CYP1A1; EROD; estrogens; ovarian cancer
资金
- NCI NIH HHS [CA50616] Funding Source: Medline
- NICHD NIH HHS [HD36007] Funding Source: Medline
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a ubiquitous pollutant and promoter of carcinogenesis. This study investigated the interaction between TCDD and different estrogens in a cancer cell line (ID8) derived from mouse ovarian epithelium. TCDD-induced ethoxyresorufin-O-deethylase (EROD) activity and cytochrome P4501A1 (CYP1A1) expression in a dose- and time-dependent manner. Estrogen receptor (ER) alpha mRNAs were constitutively expressed, but ERbeta and progesterone receptor (PR) mRNAs were not expressed. Induction of EROD by TCDD was completely inhibited by a a-naphthoflavone and phenanthroline, two aryl hydrocarbon receptor (AhR) antagonists. Progesterone and gonadotropins (FSH and LH) had no effect on the induction of EROD by TCDD. Congeners of 17beta-estradiol (E2) increased the induction of EROD activity by TCDD dose-dependently in the relative potency order: estrone (E1) > E2 > 4-hydroxyestradiol (40HE2) greater than or equal to 2-hydroxyestradiol (20HE2). In contrast, estriol (D) decreased EROD activity induced by TCDD. E2 increased TCDD-induced CYP1A1 protein and mRNA whereas E3 decreased both the protein and mRNA. E2 did not alter luciferase activity induced by TCDD in cells transfected with a luciferase reporter containing dioxin response elements (DRE) or a CYP1A1 promoter. In contrast, E3 dose-dependently decreased the luciferase activity. A pure anti-estrogen (ICI 182 780) inhibited the interaction between E2 and TCDD but did not block E3's effect on EROD activity. These results indicate that E2 may affect TCDD-induced CYP1A1 expression by a mechanism different from E3 in ID8 cells. It appears that the potentiation of E2 in the induction of CYP1A1 by TCDD occurs by a mechanism involving ERalpha since a specific ER antagonist blocked the potentiation. The inhibitory effect of E3 may be due to a rapid direct effect on EROD and a later suppression of CYP1A1 expression. (C) 2002 Published by Elsevier Science Ireland Ltd.
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