Journal Article
Species-specific antagonism of Ah receptor action by 2,2',5,5'-tetrachloro- and 2,2',3,3'4,4'-hexachlorobiphenyl
Aarts, JM; Denison, MS; Cox, MA; Schalk, MA; Garrison, PM; Tullis, K; de Haan, LH; Brouwer, A
European Journal of Pharmacology
ISSN: 0014-2999
EISSN: 1879-0712
Using recombinant cell lines showing Ah receptor-controlled expression of a luciferase reporter gene, the interaction of di-ortho-substitute polychlorinated biphenyls (PCBs) with Ah receptor agonists was studied. In the recombinant Hepa1c1c7 mouse hepatoma (H1L1.1c7) cells strong antagonistic interaction of 2,2',5,5'-tetrachlorobiphenyl (PCB52) with luciferase expression induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or 3,3',4,4'-tetrachlorobiphenyl (PCB77) was observed, and similarly, between 2,2',3,3',4,4'-hexachlorobiphenyl (PCB128) and PCB77. Accordingly, PCB52 was found to inhibit ethoxyresorufin-O-deethylase (EROD) induction by PCB77 in wild-type Hepa1c1c7 cells. In contrast, the antagonistic effect of PCB52 on TCDD-induced luciferase expression was only minor in recombinant guinea pig GPC16 colon adenocarcinoma (G16L1.1c8) and human HepG2 hepatoma (HG2L1.1c3) cells, and intermediate in recombinant H4IIE rat hepatoma (H4L1.1c4) cells. Gel retardation studies using a 32 P-labelled dioxin responsive element (DRE)-containing oligonucleotide, and ligand binding studies using [3H]TCDD, demonstrated that the species-specific antagonistic activity of PCB52 on Ah receptor-controlled luciferase expression is due to inhibition of Ah receptor ligand and DNA binding. We conclude, that Ah-mediated luciferase expression provides a useful tool to study the species specificity of Ah receptor (ant)agonists.
Animals; Base Sequence; Carcinoma, Hepatocellular; Cytochrome P-450 CYP1A1; Cytochrome P-450 Enzyme System/biosynthesis; Enzyme Induction; Guinea Pigs; Humans; Luciferases/biosynthesis; Mice; Mice, Inbred C57BL; Molecular Sequence Data; Oxidoreductases/biosynthesis; Polychlorinated Biphenyls/*pharmacology; Rats; Rats, Sprague-Dawley; Receptors, Aryl Hydrocarbon/*antagonists & inhibitors; Tetrachlorodibenzodioxin/pharmacology; Tumor Cells, Cultured
