| Human constitutive androstane receptor (CAR) and pregnane X receptor (PXR) support the hypertrophic but not the hyperplastic response to the murine nongenotoxic hepatocarcinogens phenobarbital and chlordane in vivo. | |
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MedLine Citation:
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PMID: 20403969 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Mouse nongenotoxic hepatocarcinogens phenobarbital (PB) and chlordane induce hepatomegaly characterized by hypertrophy and hyperplasia. Increased cell proliferation is implicated in the mechanism of tumor induction. The relevance of these tumors to human health is unclear. The xenoreceptors, constitutive androstane receptors (CARs), and pregnane X receptor (PXR) play key roles in these processes. Novel "humanized" and knockout models for both receptors were developed to investigate potential species differences in hepatomegaly. The effects of PB (80 mg/kg/4 days) and chlordane (10 mg/kg/4 days) were investigated in double humanized PXR and CAR (huPXR/huCAR), double knockout PXR and CAR (PXRKO/CARKO), and wild-type (WT) C57BL/6J mice. In WT mice, both compounds caused increased liver weight, hepatocellular hypertrophy, and cell proliferation. Both compounds caused alterations to a number of cell cycle genes consistent with induction of cell proliferation in WT mice. However, these gene expression changes did not occur in PXRKO/CARKO or huPXR/huCAR mice. Liver hypertrophy without hyperplasia was demonstrated in the huPXR/huCAR animals in response to both compounds. Induction of the CAR and PXR target genes, Cyp2b10 and Cyp3a11, was observed in both WT and huPXR/huCAR mouse lines following treatment with PB or chlordane. In the PXRKO/CARKO mice, neither liver growth nor induction of Cyp2b10 and Cyp3a11 was seen following PB or chlordane treatment, indicating that these effects are CAR/PXR dependent. These data suggest that the human receptors are able to support the chemically induced hypertrophic responses but not the hyperplastic (cell proliferation) responses. At this time, we cannot be certain that hCAR and hPXR when expressed in the mouse can function exactly as the genes do when they are expressed in human cells. However, all parameters investigated to date suggest that much of their functionality is maintained. |
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Authors:
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Jillian Ross; Simon M Plummer; Anja Rode; Nico Scheer; Conrad C Bower; Ortwin Vogel; Colin J Henderson; C Roland Wolf; Clifford R Elcombe |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-04-19 |
Journal Detail:
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Title: Toxicological sciences : an official journal of the Society of Toxicology Volume: 116 ISSN: 1096-0929 ISO Abbreviation: Toxicol. Sci. Publication Date: 2010 Aug |
Date Detail:
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Created Date: 2010-07-19 Completed Date: 2010-10-28 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9805461 Medline TA: Toxicol Sci Country: United States |
Other Details:
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Languages: eng Pagination: 452-66 Citation Subset: IM |
Affiliation:
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CXR Biosciences Ltd, 2 James Lindsay Place, Dundee DD1 5JJ, UK. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Aryl Hydrocarbon Hydroxylases / biosynthesis Cell Proliferation / drug effects Chlordan / toxicity* Cytochrome P-450 CYP3A / biosynthesis Humans Hyperplasia Hypertrophy Liver / drug effects, metabolism, pathology Liver Neoplasms, Experimental / chemically induced*, pathology Membrane Proteins / biosynthesis Mice Mice, Inbred C57BL Phenobarbital / toxicity* Receptors, Cytoplasmic and Nuclear / physiology* Receptors, Steroid / physiology* Species Specificity Steroid Hydroxylases / biosynthesis |
| Chemical | |
Reg. No./Substance:
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0/Membrane Proteins; 0/Receptors, Cytoplasmic and Nuclear; 0/Receptors, Steroid; 0/constitutive androstane receptor; 0/pregnane X receptor; 12789-03-6/Chlordan; 50-06-6/Phenobarbital; EC 1.14.-/Steroid Hydroxylases; EC 1.14.14.1/Aryl Hydrocarbon Hydroxylases; EC 1.14.14.1/Cyp2b10 protein, mouse; EC 1.14.14.1/Cyp3a11 protein, mouse; EC 1.14.14.1/Cytochrome P-450 CYP3A |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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