title: Vitamin D receptor activation enhances benzo[a]pyrene metabolism via CYP1A1 expression in macrophages.
abstract: Benzo[a]pyrene (BaP) activates the aryl hydrocarbon (AHR) and induces the expression of genes involved in xenobiotic metabolism, including CYP1A1. CYP1A1 is involved not only in BaP detoxification but also in metabolic activation, which results in DNA adduct formation. Vitamin D receptor (VDR) belongs to the NR1I subfamily of the nuclear receptor superfamily, which also regulates expression of xenobiotic metabolism genes. We investigated the cross-talk between AHR and VDR signaling pathways and found that 1α,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], a potent physiological VDR agonist, enhanced BaP-induced transcription of CYP1A1 in human monocytic U937 cells and THP-1 cells, breast cancer cells, and kidney epithelium-derived cells. 1,25(OH)(2)D(3) alone did not induce CYP1A1, and 1,25(OH)(2)D(3) plus BaP did not increase CYP1A2 or CYP1B1 mRNA expression in U937 cells. The combination of 1,25(OH)(2)D(3) and BaP increased CYP1A1 protein levels, BaP hydroxylation activity, and BaP-DNA adduct formation in U937 cells and THP-1 cells more effectively than BaP alone. The combined effect of 1,25(OH)(2)D(3) and BaP on CYP1A1 mRNA expression in U937 cells and/or THP-1 cells was inhibited by VDR knockdown, VDR antagonists, and α-naphthoflavone, an AHR antagonist. Electrophoretic mobility shift assays and chromatin immunoprecipitation assays showed that VDR directly bound to an everted repeat (ER) 8 motif in the human CYP1A1 promoter. Thus, CYP1A1 is a novel VDR target gene involved in xenobiotic metabolism. Induction of CYP1A1 by the activation of VDR and AHR may contribute to BaP-mediated toxicity and the physiological function of this enzyme.
authors: Division of Biochemistry, Department of Biomedical Sciences, Nihon University School of Medicine, Tokyo, Japan
authors: Manabu
authors: M
authors: Matsunawa
authors: Daisuke
authors: D
authors: Akagi
authors: Shigeyuki
authors: S
authors: Uno
authors: Kaori
authors: K
authors: Endo-Umeda
authors: Sachiko
authors: S
authors: Yamada
authors: Kazumasa
authors: K
authors: Ikeda
authors: Makoto
authors: M
authors: Makishima
mesh_terms: D001564:Benzo(a)pyrene / Q000009:adverse effects / Q000378:metabolism* / Q000494:pharmacology; D002117:Calcitriol / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D019363:Cytochrome P-450 CYP1A1 / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008658:Inactivation, Metabolic / Q000235:genetics*; D061986:MCF-7 Cells; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D047488:Retinoid X Receptors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics; D020298:U937 Cells
chemical_list: D018336:Receptors, Aryl Hydrocarbon; D018167:Receptors, Calcitriol; D047488:Retinoid X Receptors; D001564:Benzo(a)pyrene; C569463:CYP1A1 protein, human; D019363:Cytochrome P-450 CYP1A1; D002117:Calcitriol