title: Differences in Gene Regulation by Dual Ligands of Nuclear Receptors Constitutive Androstane Receptor (CAR) and Pregnane X Receptor (PXR) in HepG2 Cells Stably Expressing CAR/PXR.
abstract: The constitutive androstane receptor (CAR) and pregnane X receptor (PXR) regulate various genes involved in xenobiotics and drug metabolism. In many cases, CAR/PXR share ligands termed dual ligands of CAR/PXR. It is difficult to investigate the effect of CAR/PXR dual ligands in cell lines because CAR and PXR expression is scarcely detected in cultured cell lines. Here, we established a tetracycline-inducible human CAR and stably human PXR-overexpressing HepG2 cell line (HepTR/hCAR/hPXR) to examine CAR/PXR dual ligands. In the present study, we investigated the regulation of CYP2B6, CYP2C9, CYP3A4, and UDP-glucuronosyl transferase, which are target genes of CAR/PXR, by dual ligands of CAR/PXR in two transfectants. Activation of CAR and PXR in cells treated with a high dose of CITCO [6-(4-chlorophenyl)-imidazo(2,1-b)thiazole-5-carbaldehyde] or cotreated with rifampicin and tetracycline resulted in synergistic enhancement of CYP3A4, but not CYP2B6, CYP2C9, or UGT1A1, mRNA expression in HepTR/hCAR/hPXR cells. In contrast, this synergistic effect was not observed in HepTR/hCAR cells. These observations were also demonstrated in human primary hepatocytes. Taken together, our results suggest that dual ligands of CAR/PXR show distinct gene regulation patterns by cross-talk between CAR and PXR. Furthermore, the two newly established cell lines are useful tools to investigate dual ligands of CAR/PXR.
authors.affiliation: Department of Molecular Toxicology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan ykanno@phar.toho-u.ac.jp.
authors.forename: Yuichiro
authors.identifier: 0000-0002-7551-6410
authors.initials: Y
authors.lastname: Kanno
authors.affiliation: Department of Molecular Toxicology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Tanuma
authors.affiliation: Department of Molecular Toxicology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan.
authors.forename: Saki
authors.initials: S
authors.lastname: Yazawa
authors.affiliation: Department of Molecular Toxicology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan.
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Department of Molecular Toxicology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Inaba
authors.affiliation: Department of Molecular Toxicology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: Department of Molecular Toxicology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan.
authors.forename: Kiyomitsu
authors.initials: K
authors.lastname: Nemoto
authors.affiliation: Department of Molecular Toxicology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Inouye
mesh_terms: D000090702:Constitutive Androstane Receptor; D065702:Cytochrome P-450 CYP2B6 / Q000235:genetics / Q000378:metabolism; D065729:Cytochrome P-450 CYP2C9 / Q000235:genetics / Q000378:metabolism; D051544:Cytochrome P-450 CYP3A / Q000235:genetics / Q000378:metabolism; D054333:Drug Partial Agonism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D014453:Glucuronosyltransferase / Q000235:genetics / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology*; D008024:Ligands; D010091:Oximes / Q000494:pharmacology*; D000077297:Pregnane X Receptor; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020239:Receptor Cross-Talk; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D011987:Receptors, Steroid / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D012293:Rifampin / Q000494:pharmacology*; D013844:Thiazoles / Q000494:pharmacology*; D014162:Transfection; D000099148:UGT1A1 Enzyme
chemical_list: D000090702:Constitutive Androstane Receptor; D065702:Cytochrome P-450 CYP2B6; D065729:Cytochrome P-450 CYP2C9; D051544:Cytochrome P-450 CYP3A; D014453:Glucuronosyltransferase; D007546:Isoquinolines; D008024:Ligands; D010091:Oximes; D000077297:Pregnane X Receptor; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D012293:Rifampin; D013844:Thiazoles; D000099148:UGT1A1 Enzyme; C475093:6-(4-chlorophenyl)imidazo(2,1-b)(1,3)thiazole-5-carbaldehyde O-(3,4-dichlorobenzyl)oxime; C450260:CYP2C9 protein, human; C510163:CYP3A4 protein, human; C037850:PK 11195