title: Nuclear receptor interactions in methotrexate induction of human dehydroepiandrosterone sulfotransferase (hSULT2A1).
abstract: Cytosolic sulfotransferases (SULTs) are a major family of phase II drug-metabolizing enzymes. SULT-catalyzed sulfonation regulates hormone activities metabolizes drugs detoxifies xenobiotic toxicants bioactivates carcinogens. Human dehydroepiandrosterone sulfotransferase (hSULT2A1 DHEA-ST) plays a very important role in sulfating endogenous hydroxysteroids and exogenousxenobiotics. Our recent studies have shown that methotrexate can induce hSULT2A1 expression. To investigate the molecular mechanism involved in hSULT2A1 induction we generated the promoter sequence of hSULT2A1 by PCR and constructed a reporter gene vector. Both reporter gene assay and endogenous induction results suggested that human constitutive active receptor (hCAR) mediates the methotrexate induction of hSULT2A1 in both Caco-2 and Hep G2 cells. Human vitamin D receptor (hVDR) also upregulated hSULT2A1 gene expression while human pregnane X receptor (hPXR) downregulated it. Human pregnane X receptor suppressed hCAR-mediated methotrexate induction of hSULT2A1 in both Caco-2 and Hep G2 cells. hVDR competed with hCAR for the hSULT2A1 promoter in Caco-2 cells. hCAR inhibited hVDR-mediated vitamin D3 induction of hSULT2A1 but not methotrexate induction of hSULT2A1. These results strongly support the hypothesis that cross-talk occurs among nuclear receptors in the signal transduction pathway of hSULT2A1 and that interactions among nuclear receptors also depend on ligands (inducers) in the system.
authors.affiliation: Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Xinrong
authors.initials: X
authors.lastname: Chen
authors.forename: Smarajit
authors.initials: S
authors.lastname: Maiti
authors.forename: Jimei
authors.initials: J
authors.lastname: Zhang
authors.forename: Guangping
authors.initials: G
authors.lastname: Chen
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D000090702:Constitutive Androstane Receptor; D004790:Enzyme Induction / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D017930:Genes, Reporter; D006801:Humans; D008727:Methotrexate / Q000494:pharmacology*; D000077297:Pregnane X Receptor; D011401:Promoter Regions, Genetic / Q000235:genetics; D018167:Receptors, Calcitriol / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism; D015238:Sulfotransferases / Q000096:biosynthesis* / Q000235:genetics; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects
chemical_list: D000964:Antimetabolites, Antineoplastic; D000090702:Constitutive Androstane Receptor; D000077297:Pregnane X Receptor; D018167:Receptors, Calcitriol; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D014157:Transcription Factors; D015238:Sulfotransferases; C028152:alcohol sulfotransferase; D008727:Methotrexate