A reporter gene assay to assess the molecular mechanisms of xenobiotic-dependent induction of the human CYP3A4 gene in vitro.
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Ogg MS, Williams JM, Tarbit M, Goldfarb PS, Gray TJ, Gibson GG
A reporter gene assay to assess the molecular mechanisms of xenobiotic-dependent induction of the human CYP3A4 gene in vitro.
Xenobiotica. 1999 Mar;29(3):269-79.
- PubMed ID
- 10219967 [ View in PubMed]
- Abstract
1. A plasmid containing 1 kb of the CYP3A4 regulatory (promoter) region coupled to a reporter gene for secretary placental alkaline phosphatase (SPAP) was transfected into HepG2 cells. Transfected cells were dosed with several known inducers of CYP3A4 and the levels of SPAP were measured. The effect of co-transfecting a plasmid encoding the human glucocorticoid receptor on reporter gene activity was also examined. 2. Dexamethasone induced CYP3A4-dependent reporter gene expression in a concentration-dependent manner and induction was approximately doubled in the presence of the glucocorticoid receptor. Dexamethasone-dependent induction was blocked by RU-486 (a glucocorticoid receptor antagonist), in the presence of the co-transfected glucocorticoid receptor. 3. Induction of CYP3A4-dependent reporter gene expression and enhancement of the induction by the glucocorticoid receptor was also observed with pregnenolone-16alpha-carbonitrile (PCN), rifampicin, phenytoin, carbamazepine, phenylbutazone and phenobarbitone, all known in vivo inducers of CYP3A4 in man. 4. Metyrapone and sulfinpyrazone induced CYP3A4-dependent reporter gene expression, but induction was not enhanced by the glucocorticoid receptor. 5. Clotrimazole, erythromycin and triacetyloleandomycin (TAO) did not induce CYP3A4-dependent reporter gene expression, consistent with the observation that these inducers act through post-transcriptional mechanisms. 6. These results highlight differences in the molecular mechanisms of induction of CYP3A4 by the xenobiotics studied and indicate that the glucocorticoid receptor is involved in the induction of the CYP3A4 gene by some, but not all, CYP3A4 inducers. 7. We propose that the approach described here provides a useful in vitro approach for the identification of transcriptional regulators of the CYP3A4 gene.
DrugBank Data that Cites this Article
- Drug Enzymes
Drug Enzyme Kind Organism Pharmacological Action Actions Phenylbutazone Cytochrome P450 3A4 Protein Humans UnknownInducerDetails - Pharmaco-transcriptomics
Drug Drug Groups Gene Gene ID Change Interaction Chromosome Carbamazepine Approved Investigational CYP3A4 1576 upregulated Carbamazepine results in increased expression of CYP3A4 mRNA 7q22.1 Dexamethasone Approved Investigational Vet Approved CYP3A4 1576 upregulated Dexamethasone results in increased expression of CYP3A4 mRNA 7q22.1 Metyrapone Approved Investigational CYP3A4 1576 upregulated Metyrapone results in increased expression of CYP3A4 mRNA 7q22.1 Phenobarbital Approved Investigational CYP3A4 1576 upregulated Phenobarbital results in increased expression of CYP3A4 mRNA 7q22.1 Phenylbutazone Approved Vet Approved CYP3A4 1576 upregulated Phenylbutazone results in increased expression of CYP3A4 mRNA 7q22.1 Phenytoin Approved Vet Approved CYP3A4 1576 upregulated Phenytoin results in increased expression of CYP3A4 mRNA 7q22.1 Rifampicin Approved CYP3A4 1576 upregulated Rifampin results in increased expression of CYP3A4 mRNA 7q22.1 Sulfinpyrazone Approved CYP3A4 1576 upregulated Sulfinpyrazone results in increased expression of CYP3A4 mRNA 7q22.1