TY - JOUR T1 - Vitamin D Receptor Activation Enhances Benzo[<em>a</em>]pyrene Metabolism via CYP1A1 Expression in Macrophages JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 2059 LP - 2066 DO - 10.1124/dmd.112.046839 VL - 40 IS - 11 AU - Manabu Matsunawa AU - Daisuke Akagi AU - Shigeyuki Uno AU - Kaori Endo-Umeda AU - Sachiko Yamada AU - Kazumasa Ikeda AU - Makoto Makishima Y1 - 2012/11/01 UR - http://dmd.aspetjournals.org/content/40/11/2059.abstract N2 - 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 D3 [1,25(OH)2D3], 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)2D3 alone did not induce CYP1A1, and 1,25(OH)2D3 plus BaP did not increase CYP1A2 or CYP1B1 mRNA expression in U937 cells. The combination of 1,25(OH)2D3 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)2D3 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. ER -