Paavo Honkakoski

• Professor, PhD
• Professor (Full) at University of Eastern Finland

Exposure to metabolism-disrupting chemicals, which are a specific type of endocrine-disrupting chemical (EDC), is linked to metabolic problems such as dyslipidemia, insulin resistance, and hepatic steatosis. Steroid hormone receptors (SHRs) within the nuclear receptor superfamily are well-known targets for EDCs in reproductive tissues and, to a les...

Exposure to metabolism-disrupting chemicals (MDCs), compounds largely belonging to the group of endocrine-disrupting chemicals (EDCs), is associated with metabolic dysfunctions such as dyslipidemia, insulin resistance and hepatic steatosis. Steroid hormone receptors (SHRs) are known targets for MDCs but their regulatory environment in the presence...

Metabolism disrupting chemicals (MDCs) elicit negative effects on metabolically active organs such as the liver and the pancreas, altering normal metabolic processes. Chemicals that are known, or suspected MDCs include compounds found in everyday consumer products and food, making low-dose, continuous exposure inevitable for humans. Through the dis...

Abstract This review describes current knowledge on the expression of ocular phase I and II drug-metabolizing enzymes in the main animal species used in ocular drug development and in humans, with a focus on ocular esterases and their prodrug substrates. The eye possesses a unique metabolic profile, exhibiting a lower and restricted expression of m...

Background NAFLD is highly prevalent with limited treatment options. Bile acids (BAs) increase in the systemic circulation and liver during NAFLD progression. Changes in plasma membrane localization and zonal distribution of BA transporters can influence transport function and BA homeostasis. However, a thorough characterization of how NAFLD influe...

Aldehyde oxidase (AOX) is a cytosolic drug-metabolizing enzyme which has attracted increasing attention in drug development due to its high hepatic expression, broad substrate profile and species differences. In contrast, there is limited information on the presence and activity of AOX in extrahepatic tissues including ocular tissues. Because sever...

Mass spectrometry (MS) has been proven as an excellent tool in ocular drug research allowing analyzes from small samples and low concentrations. This review begins with a short introduction to eye physiology and ocular pharmacokinetics and the relevance of advancing ophthalmic treatments. The second part of the review consists of an introduction to...

The sodium taurocholate cotransporting polypeptide (NTCP; gene name SLC10A1) is the primary hepatic basolateral uptake transporter for conjugated bile acids and the entry receptor for the hepatitis B and D virus (HBV/HDV). Regulation of human NTCP remains a knowledge gap due to significant species differences in substrate and inhibitor selectivity...

Purpose: Melanin in intracellular organelles, melanosomes, protects the retinal pigment epithelium from ultraviolet radiation and oxidative stress (OS). However, despite the role of OS in the development of age-related macular degeneration (AMD), the effect of pigmentation-related genes on the risk of AMD onset is unclear. Methods: Finnish wet AMD...

L-type amino acid transporter 1 (LAT1) transfers essential amino acids across cell membranes. Owing to its predominant expression in the blood-brain barrier and tumor cells, LAT1 has been exploited for drug delivery and targeting to the central nervous system (CNS) and various cancers. Although the interactions of amino acids and their mimicking co...

As a multitissue organ, the eye possesses unique anatomy and physiology, including differential expression of drug-metabolizing enzymes. Several hydrolytic enzymes that play a major role in drug metabolism and bioactivation of prodrugs have been detected in ocular tissues, but data on their quantitative expression is scarce. Also, many ophthalmic d...

Hepatic cell lines serve as economical and reproducible alternatives for primary human hepatocytes. However, the utility of hepatic cell lines to examine bile acid homeostasis and cholestatic toxicity is limited due to abnormal expression and function of bile acid-metabolizing enzymes, transporters, and the absence of canalicular formation. We disc...

The constitutive androstane receptor (CAR; NR1I3) has been established as one of the main drug- and xenobiotic-responsive transcriptional regulators, collectively called xenosensors. CAR activates the expression of several oxidative, hydrolytic and conjugative drug-metabolizing enzymes and drug transporters, and therefore, it contributes to drug an...

Quantitation of ocular drug metabolism is important, but only sparse data is currently available. Herein, the pharmacokinetics of four drugs, substrates of metabolizing enzymes, was investigated in albino rabbit eyes after intracameral and intravitreal administrations. Acetaminophen, brimonidine, cefuroxime axetil, and sunitinib and their correspon...

Drug-induced liver injury (DILI) is the leading cause of acute liver failure and a major concern in drug development. Altered bile acid homeostasis via inhibition of the bile salt export pump (BSEP) is one mechanism of DILI. Dasatinib, pazopanib and sorafenib are tyrosine kinase inhibitors (TKIs) that competitively inhibit BSEP and increase serum b...

Frontotemporal lobar degeneration (FTLD) comprises a heterogenous group of fatal neurodegenerative diseases and, to date, no validated diagnostic or prognostic biomarkers or effective disease-modifying therapies exist for the different clinical or genetic subtypes of FTLD. Current treatment strategies rely on the off-label use of medications for sy...

Organic solute transporter alpha/beta (OSTα/β; SLC51A/B) is a bidirectional bile acid transporter localized on the basolateral membrane of hepatic, intestinal, and renal epithelial cells. OSTα/β plays a critical role in intestinal bile acid reabsorption and is upregulated in hepatic diseases characterized by elevated bile acids, while genetic varia...

Drug-induced liver injury (DILI) is a rare, but potentially fatal adverse outcome associated with drug use. One important mechanism of DILI involves hepatic bile acid accumulation. Investigations have focused on the bile salt export pump (BSEP), a member of the ATP-binding cassette protein family. This unidirectional, efflux transporter expressed o...

Hydrolytic reactions constitute an important pathway of drug metabolism and a significant route of prodrug activation. Many ophthalmic drugs and prodrugs contain ester groups that greatly enhance their permeation across several hydrophobic barriers in the eye before the drugs are either metabolized or released, respectively, via hydrolysis. Thus, t...

During the last two decades, the constitutive androstane receptor (CAR; NR1I3) has emerged as a master activator of drug- and xenobiotic-metabolizing enzymes and transporters that govern the clearance of both exogenous and endogenous small molecules. Recent studies indicate that CAR participates, together with other nuclear receptors (NRs) and tran...

Endocrine disruptors (EDs) are defined as chemicals that mimic, block, or interfere with hormones in the body’s endocrine systems and have been associated with a diverse array of health issues. The concept of endocrine disruption has recently been extended to metabolic alterations that may result in diseases, such as obesity, diabetes, and fatty li...

Cytochrome P450 3A is the most important CYP subfamily in humans, and CYP3A4/CYP3A5 genetic variants contribute to inter-individual variability in drug metabolism. However, no information is available for bovine CYP3A (bCYP3A). Here we described bCYP3A missense single nucleotide variants (SNVs) and evaluated their functional effects. CYP3A28, CYP3A...

Introduction Ocular ADME (absorption, distribution, metabolism & elimination) is gaining interest due to rapidly growing incidence of eye diseases and the need of new therapeutic applications. The information regarding drug‐metabolising enzymes (DME) in different ocular tissues is scattered. In addition, animal models may not be predictive of the h...

Aldehyde hydrogenases (ALDHs) belong to a large gene family involved in oxidation of both endogenous and exogenous compounds in mammalian tissues. Among ALDHs, the rat ALDH1A7 gene displays a curious strain dependence in phenobarbital (PB)-induced hepatic expression: the responsive RR strains exhibit induction of both ALDH1A7 and CYP2B mRNAs and a...

Human hepatoma cell lines are useful for evaluation of drug-induced hepatotoxicity, hepatic drug disposition, and drug-drug interactions. However, their applicability is compromised by aberrant expression of hepatobiliary transporters. This study was designed to evaluate whether extracellular matrix (Matrigel) overlay and dexamethasone (DEX) treatm...

Several transcription factors, including the pregnane X-receptor (PXR) and the constitutive androstane receptor (CAR), contribute to the complex regulation of human cytochrome P450 3A (CYP3A), representing the main CYP isoform in human liver [1]. Three genes (CYP3A28, CYP3A38 and CYP3A48) have been identified in bovine CYP3A locus, but molecular me...

Reporter assays are useful to study nuclear receptor activation and for example to evaluate the propensity of novel drug candidates to cause induction of drug-metabolizing cytochrome P450 enzymes. Here, we describe a protocol for a reverse transfection system to study the activation of human nuclear receptors constitutive androstane receptor and pr...

The regulation of cytochrome P450 3A (CYP3A) enzymes is established in humans, but molecular mechanisms of its basal and xenobiotic-mediated regulation in cattle are still unknown. Here, ~10 kbp of the bovine CYP3A28 gene promoter were cloned and sequenced, and putative transcription factor binding sites were predicted. The CYP3A28 proximal promote...

Primers used for the ex novo sequencing of bovine CYP3A28 promoter region. (PDF)

Resolution of the two encountered gaps in the bovine CYP3A28 promoter region. The re-sequencing of CYP3A28 promoter region was able to solve the first gap starting at –1492 bp revealing a sequencing artefact (A), as well as the second gap at base –2988 with a new genomic sequence (B). Two of the five single nucleotides polymorphisms (-2899T>G and -...

Identification of bCAR-responsive elements in the proximal promoter and fragment 3 in CYP3A28 promoter. Several constructs were produced to study the binding elements identified in the CYP3A28 proximal promoter (PP) and the contribution of the binding motif DR5 identified in F3. The parental PP was deleted of the whole putative region containing se...

Oligonucleotide sequences for the amplification of the bovine CYP3A28 promoter through long (ln) PCR reactions. (PDF)

bPXR-mediated transactivation of CYP3A28 proximal promoter (PP) and fragment 3 (F3) using rifampicin (RIF). (PDF)

Schematic organization of the bovine CYP3A locus. Four CYP3A coding genes are known: CYP3A28, CYP3A38, CYP3A48 and the predicted CYP3A24. The GenBank IDs and nomenclature are displayed together with the nomenclature proposed by [27]. (PDF)

Induction of CYP3A28 mRNA in BFH12 cells exposed to increasing concentrations of SR12813 and RIF for 6 hours. BFH12 cells were treated with different concentrations of SR12813 (1, 2.5, 5, 10, 25 μM) and RIF (1, 2.5, 5, 10, 25, 50 and 100 μM) for 6 hours, as described in Materials and Methods. The expression of CYP3A28 was detected by qPCR in contro...

Induction of CYP3A28 and CYP2B22 mRNA in BFH12 cells exposed for 6 and 12 hours to FL81. BFH12 cells were exposed to different concentrations (1, 3, 10 and 30 μM) of the bCAR activator, FL81, for 6 and 12 hours. The expression of CYP3A28 (A, B) and CYP2B22 (C, D) mRNA was detected by qPCR in control (0.1% DMSO) and treated cells, using RPLP0 as int...

ChIP in control BFH12 cells to quantify the binding of CAR to ER6 and DR5 binding sites. BFH12 cells were exposed to 0.1% DMSO for 6 hours. Chromatin was then isolated, subjected to ChIP using anti-human CAR antibody and quantified by qPCR as described in S1 File. Results for both ER6 and DR5 DNA regions are reported. The data shown derived from tw...

Supplemental Material and Methods and References. (PDF)

Primer sequences used for nested PCR reactions of the bovine CYP3A28 promoter. (PDF)

Oligonucleotides used in the inverse PCR procedure. (PDF)

Induction of CYP3A28 mRNA in BFH12 cells exposed for 0, 1, 3, 6, 12 and 24 hours to five prototypical CYP3A inducers. BFH12 cells were treated with different CYP3A inducers (DEX, PCN, RIF, RU486 and SR12813) at the fixed concentration 10 μM for 0 (A), 1 (B), 3 (C), 6 (D), 12 (E) and 24 (F) hours. The expression of CYP3A28 was detected by qPCR in co...

ChIP in control and treated BFH12 cells to quantify the binding of RXRα to ER6 and DR5 binding sites. BFH12 cells were exposed to 0.1% DMSO and 100 μM RU486 for 6 hours. Chromatin was isolated, subjected to ChIP using anti-human RXRα antibody and quantified by qPCR as described in S1 File. Results for ER6 and DR5 DNA regions are reported in panels...

Oligonucleotides used for the internal site-directed mutagenesis of transcription factor binding sites. (PDF)

Oligonucleotides used in qPCR ChIP. (PDF)

Modulation of CYP2B22 mRNA in BFH12 cells exposed for 6 hours to different concentrations of phenobarbital (PB). (PDF)

Induction of CAR, PXR, RXRα mRNAs in BFH12 cells exposed for 0, 1, 3, 6, 12 and 24 hours to five prototypical CYP3A inducers. BFH12 cells were treated with different CYP3A inducers (PCN, RU486, SR12813, DEX and RIF) at the fixed concentration 10 μM for 0, 1, 3, 6, 12 and 24 hours. The expression of CAR (A), PXR (B) and RXRα (C) was detected by qPCR...

CAR, PXR and RXR immunoblotting analysis of subcellular fractions isolated from untreated bovine liver. Bovine liver cytosolic and nuclear extracts were isolated according to Renisalo et al. (2012) with minor modifications. Proteins (30 μg) were subjected to immunoblotting analysis following the protocol previously published by [14]. Membranes were...

ChIP in control and treated BFH12 cells to quantify the binding of PXR to ER6 and DR5 binding sites. BFH12 cells were exposed to 0.1% DMSO and 100 μM RU486 for 6 hours. Chromatin was isolated, subjected to ChIP using anti-human PXR antibody and quantified by qPCR as described in Material and Methods. Results for ER6 and DR5 DNA regions are reported...

Human-derived hepatic cell lines are a valuable alternative to primary hepatocytes for drug metabolism, transport and toxicity studies. However, their relevance for investigations of drug-drug and drug-organic anion (e.g., bile acid, steroid hormone) interactions at the transporter level remains to be established. The aim of the present study was t...

Drug interactions with the organic solute transporter alpha/beta (OSTα/β) are understudied even though OSTα/β is an important transporter that is expressed in multiple human tissues including the intestine, kidneys and liver. In this study, an in vitro method to identify novel OSTα/β inhibitors was first developed using OSTα/β-overexpressing Flp-In...

The nuclear receptor constitutive androstane receptor (CAR; NR1I3) controls the inducible expression of many enzymes and transporters involved in drug metabolism and transport, energy metabolism and toxicity. Single nucleotide variants of CAR are quite rare and usually associated with changes in pharmacokinetics of therapeutic drugs. Recently, a no...

Background DHCR24, involved in the de novo synthesis of cholesterol and protection of neuronal cells against different stress conditions, has been shown to be selectively downregulated in neurons of the affected brain areas in Alzheimer’s disease. Methods Here, we investigated whether the overexpression of DHCR24 protects neurons against inflammat...

Plant-derived polyphenols are known to possess anti-inflammatory and antioxidant effects. In recent years, several studies have investigated their potential benefits for treating chronic diseases associated with prolonged inflammation and excessive oxidative stress, such as age-related macular degeneration (AMD). Previously, two polyphenols, fiseti...

Cocktail phenotyping using specific probe drugs for cytochrome P450 (CYP) enzymes provides information on the real-time activity of multiple CYPs. We investigated different sample preparation techniques and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with simple protein precipitation for the analysis of nine CYP pro...

Human induced pluripotent stem cell (hiPSC)-derived hepatocytes are anticipated as important surrogates for primary human hepatocytes in applications ranging from basic research to drug discovery and regenerative medicine. Although methods for differentiating hepatocyte-like cells (HLCs) from hiPSCs have developed remarkably, the limited yield of f...

Bromodomain-containing proteins are vital for controlling the expression of many pro-inflammatory genes. Consequently, compounds capable of inhibiting specific bromodomain-facilitated protein-protein interactions would be predicted to alleviate inflammation, making them valuable agents in the treatment of diseases caused by dysregulated inflammatio...

The human intestinal Caco-2 cell line has been extensively used as a model of small intestinal absorption but it lacks expression and function of cytochrome P450 enzymes, particularly CYP3A4 and CYP2C9, which are normally expressed in the intestinal epithelium. In order to increase the expression and activity of CYP isozymes in these cells, we crea...

Degeneration of retinal pigment epithelial (RPE) cells is a clinical hallmark of age-related macular degeneration (AMD), the leading cause of blindness among aged people in the Western world. Both inflammation and oxidative stress are known to play vital roles in the development of this disease. Here, we assess the ability of fisetin and luteolin,...

1. Nuclear receptors CAR (NR1I3) and PXR (NR1I2) are major ligand-activated transcriptional regulators of xenobiotic metabolism and disposition and modulators of endobiotic metabolism. Differences in xenobiotic selectivity between the human and rodent receptors are well recognized but there is lack of such information on properties of CAR and PXR i...

1. Nuclear receptors CAR (NR1I3) and PXR (NR1I2) are major ligand-activated transcriptional regulators of xenobiotic metabolism and disposition and modulators of endobiotic metabolism. Differences in xenobiotic selectivity between the human and rodent receptors are well recognized but there is lack of such information on properties of CAR and PXR i...

The constitutive androstane receptor (CAR), a member of the nuclear receptor superfamily, is a well-known xenosensor that regulates hepatic drug metabolism and detoxification. CAR activation can be elicited by a large variety of xenobiotics, including phenobarbital (PB) which is not a directly binding CAR ligand. The mechanism of CAR activation is...

Retinal pigment epithelium (RPE) plays the principal role in age-related macular degeneration (AMD), a progressive eye disease with no cure and limited therapeutical options. In the pathogenesis of AMD, degeneration of RPE cells by multiple factors including increased oxidative stress and chronic inflammation precedes the irreversible loss of photo...

Induction of cytochrome P450 (CYP) enzymes is commonly analyzed in cultured human primary hepatocytes (HPHs) by measuring CYP1A2, CYP2B6 and CYP3A4/3A5 activities after exposure to test and reference compounds. Because chemicals can both inhibit and induce CYP enzymes, this traditional approach fails to distinguish such simultaneous effects. Regula...

Misclassification of Curcuma species (family Zingiberaceae) may lead to unwanted human exposure to Curcuma elata sesquiterpenes zederone and germacrone which have caused hepatotoxicity and changes in CYP expression in laboratory animals. We investigated how these compounds interact with the human cytochrome P450 (CYP) system, in order to evaluate t...

Abstract The constitutive androstane receptor (CAR; NR1I3) has emerged as one of the main drug- and xenobiotic-sensitive transcriptional regulators. It has a major effect on the expression of several oxidative and conjugative enzymes and transporters, and hence, CAR can contribute to drug/drug interactions. Novel functions for CAR are also emerging...

Pesticides are a large group of structurally diverse toxic chemicals. The toxicity may be modified by cytochrome P450 (CYP) enzyme activity. In the current study, we have investigated effects and mechanisms of 24 structurally varying pesticides on human CYP expression. Many pesticides were found to efficiently activate human pregnane X receptor (PX...

A three-dimensional micro-scale perfusion-based two-chamber (3D-μPTC) tissue model system was developed to test the cytotoxicity of anticancer drugs in conjunction with liver metabolism. Liver cells with different cytochrome P450 (CYP) subtypes and glioblastoma multiforme (GBM) brain cancer cells were cultured in two separate chambers connected in...

Constitutive androstane receptor (CAR), along with pregnane x receptor (PXR), is an important metabolic sensor in the hepatocytes. Like all other nuclear receptors (NRs), CAR works in concert with coregulator proteins, coactivators, and corepressors which bind to the NRs. The main basis for the receptor to distinguish between coactivators and corep...

Tyrosinase is the rate-limiting enzyme responsible for melanin biosynthesis in the retinal pigment epithelium (RPE) of the eye. Melanin has an important role in retinal development, function, and protection against light-induced oxidative stress, and melanin levels are associated with age-related macular degeneration (AMD). Because the levels of an...

The human constitutive androstane receptor (CAR, NR1I3) is one of the key regulators of xenobiotic and endobiotic metabolism. The unique properties of human CAR, such as the high constitutive activity and the complexity of signaling, as well as the lack of functional and predictive cell-based assays to study the properties of the receptor, have hin...

The so-called human xenosensors, constitutive androstane receptor (hCAR), pregnane X receptor (hPXR) and aryl hydrocarbon receptor (hAhR), participate in drug metabolism and transport as well as in several endogenous processes by regulating the expression of their target genes. While the ligand specificities for hPXR and hAhR are relatively well de...

a b s t r a c t In this work, 52 diphenyl-4,5-dihydroisoxazoles and -3-hydroxy ketones were prepared and their estro-gen receptor a (ERa) and estrogen receptor b (ERb) activities were explored in order to systematize and maximize their biological activity. The biological activity was firstly screened by using ERE reporter assay to find out how arom...

Most hepatoma cell lines lack proper expression and induction of cytochrome P450 (CYP) enzymes and this deficiency hampers their use as in vitro models for drug and xenobiotic metabolism. According to previous studies, the poor expression of CYP enzymes may be due to decreases in CYP gene transcription. Two nuclear receptors (NRs), the pregnane X r...

Monocarboxylate transporters (MCTs) are transmembrane proteins capable of transferring lactate and other endogenous and exogenous monocarboxylates across the cell membrane. The aim of the present study was to assess the expression and transporter role of human MCT1, MCT3 and MCT4 in the corneal epithelium, corneal epithelial cell lines (primary HCE...

ATP-binding cassette (ABC) transporters are able to efflux their substrate drugs from the cells. We compared expression of efflux proteins in normal human corneal epithelial tissue, primary human corneal epithelial cells (HCEpiC), and corneal epithelial cell culture model (HCE model) based on human immortal cell line. Expression of multidrug resist...

The human constitutive androstane receptor (CAR, NR1I3) is an important regulator of xenobiotic metabolism and other physiological processes. So far, only few CAR agonists are known and no explicit mechanism has been proposed for their action. Thus, we aimed to generate a 3D QSAR model that could explain the molecular determinants of CAR agonist ac...

Constitutive androstane receptor (CAR, NR1I3) belongs to the nuclear receptor family of transcription factors and acts as a chemical sensor of drugs and endogenous compounds. The ligand-binding preferences of CAR are diverse, and more importantly, there are significant species differences in ligand specificity. Here, we show that while certain resi...

The constitutive androstane receptor (CAR; NR1I3) is a nuclear receptor responsible for the recognition of potentially toxic endo- and exogenous compounds whose elimination from the body is accelerated by the CAR-mediated inducible expression of metabolizing enzymes and transporters. Despite the importance of CAR, few human agonists are known so fa...

Variability of drug metabolism, especially that of the most important phase I enzymes or cytochrome P450 (CYP) enzymes, is an important complicating factor in many areas of pharmacology and toxicology, in drug development, preclinical toxicity studies, clinical trials, drug therapy, environmental exposures and risk assessment. These frequently enor...

In this paper, the preparation and systematic evaluation of estrogen receptor alpha (ER alpha) and estrogen receptor beta (ER beta) activities of some diaryl-1,3-diones and their synthetic intermediates, diaryl-4,5-dihydroisoxazoles, diaryl-3-hydroxyketones, diaryl-3-methoxyketones, and diaryl-2-(dimethyl-lambda 4-sulfanylidene)-1,3-diones, is desc...

The goals of this study were to evaluate human retinal pigment epithelial cell line (ARPE-19) for cell encapsulation and to optimize the alginate-based microencapsulation. We used immortalized ARPE-19 cells and the transfected sub-line that expresses secreted alkaline phosphatase (SEAP) reporter enzyme. Alginate was cross-linked with different diva...

The effects of maternal cigarette smoking on the transcriptome of human full-term placentas were investigated by a microarray analysis. QPCR was performed for a selected set of metabolizing genes. Differentially expressed genes were selected by fold change (+/-1.5-fold) and analysis of variance (P<0.05) between the control and smoker groups. The ex...

In the early 1960s, barbiturates were found to induce enzymes in the liver endoplasmic reticulum and to increase their own metabolism.1 With this finding, the induction by drugs of drug metabolism was suggested to be the mechanism associated with drug tolerance. Subsequently, cytochrome P450 (CYP), ...

Here we report on studies that probe whether the intracellular kinetics of plasmid DNA (pDNA) and cell surface glycosaminoglycans (GAGs) are modified during the cell cycle in a way that can be correlated with changes in gene transfer efficiency with poly(ethyleneimine) (PEI) and poly-L-lysine (PLL) polyplexes. Synchronized D407 retinal cells were t...

The constitutive androstane receptor (CAR) possesses an intrinsic basal activity whose structural basis has been analysed during the last decade. Recently, we published a homology model of the CAR ligand binding domain (LBD) based on the X-ray structures of the closely related pregnane X (PXR) and vitamin D (VDR) receptor. A detailed analysis of th...

To characterise in detail the patterns of expression and functional activities of CYP and efflux pump genes in Caco-2 cells stably transfected with human Pregnane X Receptor or murine Constitutive Androstane Receptor. Cell lines transfected with nuclear receptors were treated with established ligands, and gene expression of CYP and efflux pump gene...

Background 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 (...

Pregnane X receptor (PXR, NR1I2) and constitutive androstane receptor (CAR, NR1I3) are the principal regulators of drug/xenobiotic disposition and toxicity. These nuclear receptors display considerable cross-regulation of their target genes, and species-specific, yet promiscuous activation by a large number of structurally dissimilar ligands. Activ...