title: Highly chlorinated PCBs inhibit the human xenobiotic response mediated by the steroid and xenobiotic receptor (SXR).
abstract: Polychlorinated biphenyls (PCBs) are a family of persistent organic contaminants suspected to cause adverse effects in wildlife and humans. In rodents, PCBs bind to the aryl hydrocarbon (AhR) and pregnane X receptors (PXR) inducing the expression of catabolic cytochrome p450 enzymes of the CYP1A and 3A families. We found that certain highly chlorinated PCBs are potent activators of rodent PXR but antagonize its human ortholog, the steroid and xenobiotic receptor (SXR), inhibiting target gene induction. Thus, exposure to PCBs may blunt the human xenobiotic response, inhibiting the detoxification of steroids, bioactive dietary compounds, and xenobiotics normally mediated by SXR. The antagonistic PCBs are among the most stable and abundant in human tissues. These findings have important implications for understanding the biologic effects of PCB exposure and the use of animal models to predict the attendant risk.
authors.affiliation: Department of Developmental and Cell Biology, University of California, Irvine, California 92697-2300, USA.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Tabb
authors.forename: Vladyslav
authors.initials: V
authors.lastname: Kholodovych
authors.forename: Felix
authors.initials: F
authors.lastname: Grün
authors.forename: Changcheng
authors.initials: C
authors.lastname: Zhou
authors.forename: William J
authors.initials: WJ
authors.lastname: Welsh
authors.forename: Bruce
authors.initials: B
authors.lastname: Blumberg
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D004032:Diet; D004785:Environmental Pollutants / Q000494:pharmacology* / Q000506:poisoning*; D006801:Humans; D008658:Inactivation, Metabolic; D051379:Mice; D011078:Polychlorinated Biphenyls / Q000494:pharmacology* / Q000506:poisoning*; D000077297:Pregnane X Receptor; D051381:Rats; D011987:Receptors, Steroid / Q000187:drug effects* / Q000502:physiology*; D018570:Risk Assessment; D013256:Steroids / Q000378:metabolism; D015262:Xenobiotics / Q000378:metabolism*
chemical_list: D004785:Environmental Pollutants; D000077297:Pregnane X Receptor; D011987:Receptors, Steroid; D013256:Steroids; D015262:Xenobiotics; D011078:Polychlorinated Biphenyls