title: PXR-mediated transcriptional activation of CYP3A4 by cryptotanshinone and tanshinone IIA.
abstract: Danshen (Radix Salvia miltiorrhiza) is a famous Traditional Chinese Medicine used widely for the treatment of coronary heart disease and cerebrovascular disease. Diterpenoid tanshinones including tanshinone I, tanshinone IIA and cryptotanshinone are the major bioactive components from Danshen herb. Previous reports have demonstrated that Danshen extracts could induce the expression of CYP3A in rodents, however, the constituents responsible for Danshen-mediated CYP3A induction and the underlying molecular mechanisms remain unknown. The discovery of a family of nuclear receptors such as pregnane X receptor (PXR), constitutive androstane receptor (CAR) and glucocorticoid receptor (GR) gives insight into the molecular explanation of CYP3A induction by xenobiotics. In the present study, interactions between Danshen constituents and human PXR were evaluated using a reporter gene assay. Our observations showed that Danshen ethanol extract could activate human PXR and induce the CYP3A4 reporter construct in HepG2 cells. Tanshinone IIA and cryptotanshinone were identified as efficacious PXR agonists, and cryptotanshinone activated the CYP3A4 promoter more strongly than tanshinone IIA. Furthermore, CAR and GR were also involved in the induction of CYP3A4 expression by tanshinones, though their roles seemed not as important as PXR. Treatment of LS174T cells with cryptotanshinone or tanshinone IIA resulted in a significant increase of CYP3A4 mRNA, which was consistent with the results from the reporter gene assay. Collectively, activation of PXR and the resultant CYP3A4 induction mediated by cryptotanshinone and tanshinone IIA provide a molecular mechanism for previously observed CYP3A induction by Danshen extracts, and our findings also suggest that caution should be taken when Danshen products are used in combination with therapeutic drugs metabolized by CYP3A4.
authors.affiliation: Department of Pharmaceutical Analysis and Drug Metabolism, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Chunna
authors.initials: C
authors.lastname: Yu
authors.forename: Shanshan
authors.initials: S
authors.lastname: Ye
authors.forename: Hongying
authors.initials: H
authors.lastname: Sun
authors.forename: Yao
authors.initials: Y
authors.lastname: Liu
authors.forename: Lingbo
authors.initials: L
authors.lastname: Gao
authors.forename: Chaofeng
authors.initials: C
authors.lastname: Shen
authors.forename: Shuqing
authors.initials: S
authors.lastname: Chen
authors.forename: Su
authors.initials: S
authors.lastname: Zeng
mesh_terms: D045784:Abietanes; D045744:Cell Line, Tumor; D000090702:Constitutive Androstane Receptor; D051544:Cytochrome P-450 CYP3A / Q000096:biosynthesis / Q000235:genetics*; D004365:Drugs, Chinese Herbal / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D017930:Genes, Reporter; D006801:Humans; D010616:Phenanthrenes / Q000737:chemistry / Q000494:pharmacology*; D000077297:Pregnane X Receptor; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000235:genetics; D011987:Receptors, Steroid / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D027561:Salvia miltiorrhiza; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects*
chemical_list: D045784:Abietanes; D000090702:Constitutive Androstane Receptor; D004365:Drugs, Chinese Herbal; D010616:Phenanthrenes; D000077297:Pregnane X Receptor; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011965:Receptors, Glucocorticoid; D011987:Receptors, Steroid; D011994:Recombinant Proteins; D014157:Transcription Factors; C021751:tanshinone; C028972:dan-shen root extract; C037886:cryptotanshinone; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human