Byakangelicin induces cytochrome P450 3A4 expression via transactivation of pregnane X receptors in human hepatocytes

Abstract

BACKGROUND AND PURPOSEByakangelicin is found in extracts of the root of Angelica dahurica, used in Korea and China as a traditional medicine to treat colds, headache and toothache. As byakangelicin can inhibit the effects of sex hormones, it may increase the catabolism of endogenous hormones. Therefore, this study investigated the effects of byakangelicin on the cytochrome P450 isoform cytochrome (CY) P3A4 in human hepatocytes. EXPERIMENTAL APPROACHCultures of human hepatocytes and a hepatoma cell line (Huh7 cells) were used. mRNA and protein levels were measured by quantitative reverse transcription-polymerase chain reaction and Western blot. Plasmid constructs and mutants were prepared by cloning and site-directed mutagenesis. Reporter (luciferase) activity was determined by transient co-transfection experiments. KEY RESULTSIn human primary hepatocytes, byakangelicin markedly induced the expression of CYP3A4 both at the mRNA level (approximately fivefold) and the protein level (approximately threefold) but did not affect expression of human pregnane X receptor (hPXR). In reporter assays, byakangelicin activated CYP3A4 promoter in a concentration-dependent manner (EC50 = 5 mM), and this activation was enhanced by co-transfection with hPXR. Further reporter assays demonstrated that the eNR4 binding element in the CYP3A4 promoter was required for the transcriptional activation of CYP3A4 by byakangelicin. CONCLUSIONS AND IMPLICATIONSByakangelicin induced expression and activity of CYP3A4 in human hepatocytes. This induction was achieved by the transactivation of PXR and not by increased expression of PXR. Therefore, byakangelicin is likely to increase the expression of all PXR target genes (such as MDR1) and induce a wide range of drug-drug interactions. Abbreviations

Extracts of Immature Orange (Aurantii fructus immaturus) and Citrus Unshiu Peel (Citri unshiu pericarpium) Induce P-Glycoprotein and Cytochrome P450 3A4 Expression via Upregulation of Pregnane X Receptor

“…Therefore, agents that alter PXR activity are expected to affect the absorption and metabolism of concomitantly administered drugs ( Qiao et al, 2013 ). PXR activity is altered in at least one of the following ways: (i) activation of PXR function by PXR ligands or (ii) induction of PXR protein expression ( Yang et al, 2011 ). Most P-gp and CYP3A4 inducers are PXR ligands and activate PXR function, and a few directly stimulate PXR protein expression.…”

The Synergistic Antitumor Effect of Tanshinone IIA Plus Adriamycin on Human Hepatocellular Carcinoma Xenograft in BALB/C Nude Mice and Their Influences on Cytochrome P450 CYP3A4 In Vivo

“…Previously, it has been established that the active ingredients of Chinese medicine could activate the PXR/CYP3A4 pathway. For example, the extracts of Wu Wei Zi, Gan Cao, Echinacea purpurea , and Byakangelicin could activate PXR to induce the CYP3A4 transcriptional expression in HepG2 cells [ 63 – 65 ]. Other papers have presented convincing evidence that Tan IIA was an efficacious PXR agonist in vitro .…”

Natural Ligands for Nuclear Receptors: Biology and Potential Therapeutic Applications

“…The result was that CYP3A4 expression mediated by byakangelicin increased markedly without change in PXR expression. Indeed byakangelicin induced CYP3A4 expression in a concentrationdependent (0-50 μM) and a time dependent (0-24 h) manner not through inducing the PXR expression but through promoting PXR transactivaction [304].…”