title: Identification of chemical modulators of the constitutive activated receptor (CAR) in a gene expression compendium.
abstract: The nuclear receptor family member constitutive activated receptor (CAR) is activated by structurally diverse drugs and environmentally-relevant chemicals leading to transcriptional regulation of genes involved in xenobiotic metabolism and transport. Chronic activation of CAR increases liver cancer incidence in rodents, whereas suppression of CAR can lead to steatosis and insulin insensitivity. Here, analytical methods were developed to screen for chemical treatments in a gene expression compendium that lead to alteration of CAR activity. A gene expression biomarker signature of 83 CAR-dependent genes was identified using microarray profiles from the livers of wild-type and CAR-null mice after exposure to three structurally-diverse CAR activators (CITCO, phenobarbital, TCPOBOP). A rank-based algorithm (Running Fisher's algorithm (p-value ≤ 10(-4))) was used to evaluate the similarity between the CAR biomarker signature and a test set of 28 and 32 comparisons positive or negative, respectively, for CAR activation; the test resulted in a balanced accuracy of 97%. The biomarker signature was used to identify chemicals that activate or suppress CAR in an annotated mouse liver/primary hepatocyte gene expression database of ~1850 comparisons. CAR was activated by 1) activators of the aryl hydrocarbon receptor (AhR) in wild-type but not AhR-null mice, 2) pregnane X receptor (PXR) activators in wild-type and to lesser extents in PXR-null mice, and 3) activators of PPARα in wild-type and PPARα-null mice. CAR was consistently activated by five conazole fungicides and four perfluorinated compounds. Comparison of effects in wild-type and CAR-null mice showed that the fungicide propiconazole increased liver weight and hepatocyte proliferation in a CAR-dependent manner, whereas the perfluorinated compound perfluorooctanoic acid (PFOA) increased these endpoints in a CAR-independent manner. A number of compounds suppressed CAR coincident with increases in markers of inflammation including acetaminophen, concanavalin A, lipopolysaccharide, and 300 nm silica particles. In conclusion, we have shown that a CAR biomarker signature coupled with a rank-based similarity method accurately predicts CAR activation. This analytical approach, when applied to a gene expression compendium, increased the universe of known chemicals that directly or indirectly activate CAR, highlighting the promiscuous nature of CAR activation and signaling through activation of other xenobiotic-activated receptors.
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: Keiyu
authors.initials: K
authors.lastname: Oshida
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: Naresh
authors.initials: N
authors.lastname: Vasani
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: Carlton
authors.initials: C
authors.lastname: Jones
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: Tanya
authors.initials: T
authors.lastname: Moore
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: Susan
authors.initials: S
authors.lastname: Hester
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: Stephen
authors.initials: S
authors.lastname: Nesnow
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: Scott
authors.initials: S
authors.lastname: Auerbach
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: David R
authors.initials: DR
authors.lastname: Geter
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Aleksunes
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: Russell S
authors.initials: RS
authors.lastname: Thomas
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: Dawn
authors.initials: D
authors.lastname: Applegate
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: Curtis D
authors.initials: CD
authors.lastname: Klaassen
authors.affiliation: National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, (KO, NV, CJ, TM, SH, SN), NIEHS (SA) and Bayer CropScience (DRG), Research Triangle Park, NC 27711; Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (LMA), The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (RST), RegeneMed, San Diego, CA (DA), Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA (CDK) and the Integrated Systems Toxicology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Research Triangle Park, NC 27711 (JCC).
authors.forename: J Christopher
authors.initials: JC
authors.lastname: Corton
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D000090702:Constitutive Androstane Receptor; D004353:Drug Evaluation, Preclinical; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D000077297:Pregnane X Receptor; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics* / Q000378:metabolism; D011987:Receptors, Steroid / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D015415:Biomarkers; D000090702:Constitutive Androstane Receptor; D000077297:Pregnane X Receptor; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid
keywords: aryl hydrocarbon receptor; conazoles; constitutive activated receptor; liver cancer; metabolic syndrome; perfluorinated compounds; peroxisome proliferator-activated receptor; pregnane X receptor; steatosis; transcript profiling