title: In vivo and mechanistic evidence of nuclear receptor CAR induction by artemisinin.
abstract: Artemisinin (a sesquiterpene lactone endoperoxide) has become important in multi-drug treatment of malaria. There is evidence that artemisinin induces drug metabolism which could result in drug-drug interactions. The objective of this study was to characterize the inductive properties of artemisinin on drug-metabolizing cytochrome P450 (CYP450) enzymes. The possibility of artemisinin to induce CYP450 was studied in artemisinin-treated (orally for four days) and vehicle-treated rats using reverse transcriptase polymerase chain reaction (RT-PCR). The effect on enzymatic activities in mouse microsomes from multiple artemisinin administration (intraperitonally) to mice were also studied as well as the effect on the expression in mouse primary hepatocytes and HEK293 cells. Increased CYP2B1 mRNA levels in rats could be seen after artemisinin treatment as well as a weak but reproducible increase in the intensity of CYP1A2. Administration of artemisinin to mice up-regulated hepatic CYP2B10-dependent, and to a lesser extent, CYP2A5-dependent enzyme activities. In primary hepatocyte culture, artemisinin significantly increased the CYP2B10 mRNA levels whereas the CYP2A5 mRNA levels were increased to a lesser extent. No significant changes were seen in the levels of other CYP enzymes. Artemisinin was an activator of constitutive androstane receptor (CAR) but not pregnane X receptor (PXR) in HEK293 cells. The results demonstrate that the drug exerts its effects on drug metabolism via the CAR receptor that results in up-regulation of genes such as the Cyp2b. The weaker up-regulation of CYP2A5 might also be CAR-dependent or alternatively, a consequence of artemisinin toxicity. The results of this study are of importance when predicting potential drug-drug interactions in multi-drug therapies with artemisinin.
authors.affiliation: Uppsala University, Uppsala, Sweden.
authors.forename: U S H
authors.initials: US
authors.lastname: Simonsson
authors.forename: M
authors.initials: M
authors.lastname: Lindell
authors.forename: F
authors.initials: F
authors.lastname: Raffalli-Mathieu
authors.forename: A
authors.initials: A
authors.lastname: Lannerbro
authors.forename: P
authors.initials: P
authors.lastname: Honkakoski
authors.forename: M A
authors.initials: MA
authors.lastname: Lang
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000890:Anti-Infective Agents / Q000008:administration & dosage*; D037621:Artemisinins / Q000008:administration & dosage*; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D002478:Cells, Cultured; D000090702:Constitutive Androstane Receptor; D019388:Cytochrome P-450 CYP1A2 / Q000187:drug effects; D065637:Cytochrome P-450 CYP2A6; D019362:Cytochrome P-450 CYP2B1 / Q000187:drug effects; D003577:Cytochrome P-450 Enzyme System / Q000187:drug effects*; D000072467:Cytochrome P450 Family 2; D004347:Drug Interactions; D004790:Enzyme Induction / Q000187:drug effects; D022781:Hepatocytes; D008297:Male; D051379:Mice; D006899:Mixed Function Oxygenases / Q000378:metabolism; D000077297:Pregnane X Receptor; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects*; D011987:Receptors, Steroid / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012717:Sesquiterpenes / Q000008:administration & dosage*; D014157:Transcription Factors / Q000187:drug effects*
chemical_list: D000890:Anti-Infective Agents; D037621:Artemisinins; D000090702:Constitutive Androstane Receptor; D000077297:Pregnane X Receptor; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D012717:Sesquiterpenes; D014157:Transcription Factors; D003577:Cytochrome P-450 Enzyme System; C031327:artemisinin; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C585520:Cyp2a5 protein, mouse; D019388:Cytochrome P-450 CYP1A2; D065637:Cytochrome P-450 CYP2A6; D019362:Cytochrome P-450 CYP2B1; D000072467:Cytochrome P450 Family 2