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Sookoian S, Castaño G, Burgueño A, Gianotti TF, Pirola CJ. Association of the multidrug-resistance-associated protein gene (ABCC2) variants with intrahepatic cholestasis of pregnancy. J Hepatol 2008; 48:125-32. [PMID: 17997497 DOI: 10.1016/j.jhep.2007.08.015] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 07/27/2007] [Accepted: 08/13/2007] [Indexed: 01/16/2023]
Abstract
BACKGROUND/AIMS We hypothesized that common genetic variation at ABCC2 influences ICP susceptibility. Hence we studied the association of single nucleotide polymorphisms (SNPs) of promoter, coding and non-coding regions of ABCC2 and intrahepatic cholestasis of pregnancy (ICP). METHODS 70 ICP patients and 112 healthy pregnant women in the third trimester of their pregnancies were included in a cross sectional study. Four tag SNPs (rs717620 A/G; rs2756105 C/T; rs2002042 C/T; rs3740066 A/G) encompassing 70 kb in chr.10 and representing 46 polymorphic sites (r(2) > 0.8) were genotyped. Besides, 2 additional SNPs (rs17222723 A/T and rs8187710 G/A) were included. RESULTS In univariate analysis, rs2002042 and rs3740066 were significantly associated with ICP (p < 0.04 and 0.01, respectively) but after multiple testing correction, only rs3740066 remained significantly associated with disease status (p < 0.03). We also observed a positive association between the rs3740066 and ALT, AST, alkaline phosphatase and total and conjugated bilirubin concentrations. Consistent with the analysis of individual markers, we observed that haplotype frequency of the ABCC2 gene in ICP patients significantly differed from controls (p < 0.03). CONCLUSIONS We found an association between the rs3740066 in exon 28 of ABCC2 gene and ICP. The risk of disease for homozygous AA carriers is 4-fold higher (OR 4.44 CI 95% 1.83-10.78, p < 0.001) in comparison with GG carriers.
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Affiliation(s)
- Silvia Sookoian
- Instituto de Investigaciones Medicas A. Lanari, Departamento de Genetica y Biología Molecular de Enfermedades Complejas, Universidad de Buenos Aires, CONICET, Combatientes de Malvinas 3150, Buenos Aires 1427, Argentina
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152
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Marion TL, Leslie EM, Brouwer KLR. Use of Sandwich-Cultured Hepatocytes To Evaluate Impaired Bile Acid Transport as a Mechanism of Drug-Induced Hepatotoxicity. Mol Pharm 2007; 4:911-8. [DOI: 10.1021/mp0700357] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tracy L. Marion
- Curriculum in Toxicology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, Department of Physiology, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7, and School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Elaine M. Leslie
- Curriculum in Toxicology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, Department of Physiology, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7, and School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Kim L. R. Brouwer
- Curriculum in Toxicology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, Department of Physiology, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7, and School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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153
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Ho RH, Choi L, Lee W, Mayo G, Schwarz UI, Tirona RG, Bailey DG, Stein CM, Kim RB. Effect of drug transporter genotypes on pravastatin disposition in European- and African-American participants. Pharmacogenet Genomics 2007; 17:647-56. [PMID: 17622941 PMCID: PMC4063287 DOI: 10.1097/fpc.0b013e3280ef698f] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Our aims were to evaluate the effects of polymorphisms in the hepatic drug uptake transporter organic anion transporting polypeptide 1B1 (OATP1B1, SLCO1B1) and efflux transporters multidrug resistance-associated protein 2 (MRP2, ABCC2), bile salt export pump (BSEP, ABCB11), and breast cancer-related protein (BCRP, ABCG2) on single-dose pravastatin pharmacokinetics in healthy European- and African-American participants. METHODS The pharmacokinetics of a single oral 40 mg dose of pravastatin was determined in 107 participants (69 European-Americans and 38 African-Americans). Participants were genotyped for known OATP1B1, MRP2, BSEP, and BCRP polymorphisms. Baseline serum total and unconjugated plasma bilirubin concentrations were also determined. RESULTS OATP1B1 genotypes were ethnicity-dependent with a 521C allele frequency of approximately 15% in European-Americans and approximately 1% in African-Americans. SLCO1B1 521TC genotype was associated with significantly higher pravastatin area under the curve [AUC(0-5)] (P=0.01) and Cmax values (P<0.05). When analyzed by diplotype, SLCO1B1*1a/*15 (N=8) participants exhibited 45 and 80% higher AUC values than SLCO1B1*1a/*1a (N=29) (P=0.013) and SLCO1B1*1b/*1b (N=34) (P=0.001) carriers, respectively. SLCO1B1*15/*15 (N=2) participants exhibited 92 and 149% higher AUC values than SLCO1B1*1a/*1a (P=0.017) and SLCO1B1*1b/*1b (P=0.011) carriers, respectively. European-Americans had significantly higher plasma pravastatin AUC(0-5) (P=0.01) and Cmax values (P=0.009) than African-Americans. Neither ABCC2, ABCB11, nor ABCG2 genotypes were associated with differences in pravastatin pharmacokinetics. We did not observe an effect of SLCO1B1 genotype on baseline total or unconjugated bilirubin levels. CONCLUSION SLCO1B1 genotype, in particular the 521C allele, had a significant effect on the pharmacokinetics of pravastatin. Even when adjusted for the presence of the SLCO1B1 521C or 388G variant allele, European-Americans demonstrated significantly higher pravastatin AUC and Cmax values than African-Americans.
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Affiliation(s)
- Richard H. Ho
- Department of Pediatrics and Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Leena Choi
- Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Wooin Lee
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Gail Mayo
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Ute I. Schwarz
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Division of Clinical Pharmacology, Department of Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Rommel G. Tirona
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
- Division of Clinical Pharmacology, Department of Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - David G. Bailey
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
- Division of Clinical Pharmacology, Department of Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - C. Michael Stein
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Richard B. Kim
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Division of Clinical Pharmacology, Department of Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
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154
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Abstract
PURPOSE OF REVIEW This review focuses on the recent advances in cholestatic liver diseases. While there is an emphasis placed on translational and treatment-focused studies, basic science studies with the greatest impact on the field are also covered. RECENT FINDINGS Highlights include new discoveries for the role of the farsenoid X receptor and sodium-dependent taurocholate cotransporting polypeptide; new insights into the pathogenesis of progressive familial intrahepatic cholestasis type 1, biliary atresia, intrahepatic cholestasis of pregnancy, and primary biliary cirrhosis; new information for assessing prognosis in biliary atresia and primary biliary cirrhosis; and important clinical trials in intrahepatic cholestasis of pregnancy, primary biliary cirrhosis and primary sclerosing cholangitis. SUMMARY The studies of 2006 have furthered our understanding of cholestasis and cholestatic syndromes. While we continue to add to our knowledge of pathogenesis and treatment for many of these diseases, much work remains.
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Affiliation(s)
- Jacqueline G O'Leary
- Gastrointestinal Unit, Department of Medicine, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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155
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Simon C, Stieger B, Kullak-Ublick GA, Fried M, Mueller S, Fritschy JM, Wieser HG, Pauli-Magnus C. Intestinal expression of cytochrome P450 enzymes and ABC transporters and carbamazepine and phenytoin disposition. Acta Neurol Scand 2007; 115:232-42. [PMID: 17376120 DOI: 10.1111/j.1600-0404.2006.00761.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
OBJECTIVES Interindividual variability in intestinal absorption and bioavailability might contribute to inadequate control of seizures under treatment with carbamazepine and phenytoin. We therefore correlated intestinal expression levels and genetics of CYP3A4, CYP2C9/19, MDR1 and MRP2 with dose requirement and plasma levels of carbamazepine and phenytoin. MATERIALS AND METHODS Epileptic patients on carbamazepine (n = 29) or phenytoin (n = 15) were stratified into a 'high'-dose (carbamazepine > or =800 mg/day, phenytoin > or =300 mg/day) and a 'low'-dose group (carbamazepine < or =600 mg/day, phenytoin < or =200 mg/day). Duodenal biopsies and DNA were obtained for Western blotting and genotyping studies. RESULTS Low carbamazepine plasma levels showed a trend towards higher intestinal MDR1 expression (P = 0.06). Furthermore, carbamazepine dose was positively correlated with MRP2 expression (P = 0.1). Moreover, MDR1 expression and carbamazepine and phenytoin dose requirement was influenced by the genotype in position 2677 and 3435 of the MDR1 gene. CONCLUSION Differences in intestinal MDR1 and MRP2 expression may influence carbamazepine and phenytoin disposition and may account for interindividual pharmacokinetic variability.
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Affiliation(s)
- C Simon
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
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156
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Jung C, Driancourt C, Baussan C, Zater M, Hadchouel M, Meunier-Rotival M, Guiochon-Mantel A, Jacquemin E. Prenatal molecular diagnosis of inherited cholestatic diseases. J Pediatr Gastroenterol Nutr 2007; 44:453-8. [PMID: 17414143 DOI: 10.1097/mpg.0b013e318036a569] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
OBJECTIVES Progressive familial intrahepatic cholestasis (PFIC) and to a lesser extent, Alagille syndrome, often lead to end-stage liver disease during childhood. We report our experience of DNA-based prenatal diagnosis of PFIC1-3 and Alagille syndrome. PATIENTS AND METHODS Four molecular antenatal diagnoses were performed in 3 PFIC families and 17 in 11 Alagille syndrome families. DNA was isolated from chorionic villus or cultured amniocyte samples from women, without pregnancy complications. RESULTS All four foetuses with a family history of PFIC1, 2, or 3 were heterozygous for an ATP8B1, ABCB11, or ABCB4 mutation and pregnancies were continued. Three of the infants were healthy after birth, and 1 premature infant, who had an ABCB4 mutation, experienced transient neonatal cholestasis. Among the families with a history of de novo JAG1 mutation, none of the foetuses was mutated, versus 40% of those with a history of familial mutation. Of 4 pregnant women with a JAG1-mutated foetus, 3 cut short their pregnancy and 1 gave birth to a child with overt Alagille syndrome. CONCLUSIONS Molecular antenatal diagnosis of PFIC1-3 and Alagille syndrome is reliable because clinical outcome after birth corresponded to molecular foetal data.
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Affiliation(s)
- Camille Jung
- Pediatric Hepatology and National Reference Centre for Biliary Atresia, Bicêtre Hospital, University of Paris-South XI, AP-HP, Paris, France
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157
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Leslie EM, Watkins PB, Kim RB, Brouwer KLR. Differential inhibition of rat and human Na+-dependent taurocholate cotransporting polypeptide (NTCP/SLC10A1)by bosentan: a mechanism for species differences in hepatotoxicity. J Pharmacol Exp Ther 2007; 321:1170-8. [PMID: 17374746 DOI: 10.1124/jpet.106.119073] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Bile acid accumulation in hepatocytes due to inhibition of the canalicular bile salt export pump (BSEP/ABCB11) has been proposed as a mechanism for bosentan-induced hepatotoxicity. The observation that bosentan does not induce hepatotoxicity in rats, although bosentan has been reported to inhibit rat Bsep and cause elevated serum bile acids, challenges this mechanism. The lack of hepatotoxicity could be explained if bosentan inhibited hepatocyte uptake as well as canalicular efflux of bile acids. In the current study, bosentan was found to be a more potent inhibitor of Na(+)-dependent taurocholate uptake in rat (IC(50) 5.4 microM) than human (IC(50) 30 microM) suspended hepatocytes. In addition, bosentan was a more potent inhibitor of taurocholate uptake by rat Na(+)-dependent taurocholate co-transporting polypeptide (Ntcp/Slc10a1) (IC(50) 0.71 microM) than human NTCP (SLC10A1) (IC(50) 24 microM) expressed in HEK293 cells. Thus, bosentan is a more potent inhibitor of Ntcp than NTCP, and this should result in less intrahepatocyte accumulation of bile acids in rats during bosentan treatment. To begin characterization of this species difference, two chimeric molecules were generated and expressed in HEK293 cells; NTCP(1-140)/Ntcp(141-362) and Ntcp(1-140)/NTCP(141-349). The mode of bosentan inhibition was noncompetitive for Ntcp, and competitive for NTCP (K(i) 18 microM) and NTCP(1-140)/Ntcp(141-362) (K(i) 1.7 microM); bosentan affected both the K(m) and V(max) of Ntcp(1-140)/NTCP(141-349) (K(i) 7.0 microM). The carboxyl portions of NTCP and Ntcp were found to confer species differences in basal taurocholate transport V(max). In conclusion, differential inhibition of Ntcp and NTCP may represent a novel mechanism for species differences in bosentan-induced hepatotoxicity.
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Affiliation(s)
- Elaine M Leslie
- School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7360, USA
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158
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Abstract
Opioids are used for acute and chronic pain and dependency. They have a narrow therapeutic index and large interpatient variability in response. Genetic factors regulating their pharmacokinetics (metabolizing enzymes, transporters) and pharmacodynamics (receptors and signal transduction elements) are contributors to such variability. The polymorphic CYP2D6 regulates the O-demethylation of codeine and other weak opioids to more potent metabolites with poor metabolizers having reduced antinociception in some cases. Some opioids are P-glycoprotein substrates, whereas, ABCB1 genotypes inconsistently influence opioid pharmacodynamics and dosage requirements. Single-nucleotide polymorphisms in the mu opioid receptor gene are associated with increasing morphine, but not methadone dosage requirements and altered efficacy of mu opioid agonists and antagonists. As knowledge regarding the interplay between genes affecting opioid pharmacokinetics including cerebral kinetics and pharmacodynamics increases, our understanding of the role of pharmacogenomics in mediating interpatient variability in efficacy and side effects to this important class of drugs will be better informed. Opioid drugs as a group have withstood the test of time in their ability to attenuate acute and chronic pain. Since the isolation of morphine in the early 1800s by Friedrich Sertürner, a large number of opioid drugs beginning with modification of the 4,5-epoxymorphinan ring structure were developed in order to improve their therapeutic margin, including reducing dependence and tolerance, ultimately without success.
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Affiliation(s)
- Andrew A Somogyi
- Discipline of Pharmacology, School of Medical Sciences, University of Adelaide, Adelaide, Australia.
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159
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Lang C, Meier Y, Stieger B, Beuers U, Lang T, Kerb R, Kullak-Ublick GA, Meier PJ, Pauli-Magnus C. Mutations and polymorphisms in the bile salt export pump and the multidrug resistance protein 3 associated with drug-induced liver injury. Pharmacogenet Genomics 2007; 17:47-60. [PMID: 17264802 DOI: 10.1097/01.fpc.0000230418.28091.76] [Citation(s) in RCA: 213] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Increasing evidence suggests that a genetically determined functional impairment of the hepatocellular efflux transporters bile salt export pump (BSEP, ABCB11) and multidrug resistance protein 3 (MDR3, ABCB4) play a pathophysiological role in the development of drug-induced liver injury. The aim of this study was therefore to describe the extent of genetic variability in ABCB11 and ABCB4 in patients with drug-induced liver injury and to in vitro functionally characterize newly detected ABCB11 mutations and polymorphisms. METHODS ABCB11 and ABCB4 were sequenced in 23 patients with drug-induced cholestasis and 13 patients with drug-induced hepatocellular injury. Ninety-five healthy Caucasians served as the control group. Reference and mutant BSEP were expressed in Sf9 cells and ATP-dependent transport of [H]-taurocholate was measured in a rapid filtration assay. RESULTS Four highly conserved nonsynonymous mutations were specific for drug-induced liver injury [ABCB11: D676Y (drug-induced cholestasis) and G855R (drug-induced cholestasis); ABCB4: I764L (drug-induced cholestasis) and L1082Q (drug-induced hepatocellular injury)]. Furthermore, a polymorphism in exon 13 of ABCB11 (V444A), which is associated with decreased hepatic BSEP expression was significantly more frequent in drug-induced cholestasis patients than in drug-induced hepatocellular injury patients and healthy controls (76 versus 50 and 59% in drug-induced cholestasis patients, drug-induced hepatocellular injury patients and healthy controls, respectively; P<0.05). The in-vitro transport activity of the V444A and the D676Y BSEP constructs was similar, whereas the G855R mutation was nonfunctional. CONCLUSION In summary, our data support a role of ABCB11 and ABCB4 mutations and polymorphisms in drug-induced cholestasis. Genotyping of selected patients with acquired cholestasis might help to identify individuals with a genetic predisposition.
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Affiliation(s)
- Carmen Lang
- Division of Clinical Pharmacology and Toxicology, University Hospital Zurich, Switzerland
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160
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Sakurai A, Kurata A, Onishi Y, Hirano H, Ishikawa T. Prediction of drug-induced intrahepatic cholestasis:in vitroscreening and QSAR analysis ofdrugs inhibiting the human bile salt export pump. Expert Opin Drug Saf 2006; 6:71-86. [PMID: 17181454 DOI: 10.1517/14740338.6.1.71] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Drug-induced intrahepatic cholestasis is one of the major causes of hepatotoxicity, which often occur during the drug discovery and development process. Human ATP-binding cassette transporter ABCB11 (sister of P-glycoprotein/bile salt export pump) mediates the elimination of cytotoxic bile salts from liver cells to bile, and, therefore, plays a critical role in the generation of bile flow. The authors have recently developed in vitro high-speed screening and quantitative structure-activity relationship analysis methods to investigate the interaction of ABCB11 with a variety of compounds. Based on the extent of inhibition of the bile salt export pump, the authors analysed the quantitative structure-activity relationship to identify chemical groups closely associated with the inhibition of ABCB11. This approach provides a new tool to predict compounds with a potential risk of drug-induced intrahepatic cholestasis.
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Affiliation(s)
- Aki Sakurai
- Tokyo Institute of Technology, Department of Biomolecular Engineering, Graduate School of Bioscience and Biotechnology, 4259-B-60 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
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161
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Niemi M, Arnold KA, Backman JT, Pasanen MK, Gödtel-Armbrust U, Wojnowski L, Zanger UM, Neuvonen PJ, Eichelbaum M, Kivistö KT, Lang T. Association of genetic polymorphism in ABCC2 with hepatic multidrug resistance-associated protein 2 expression and pravastatin pharmacokinetics. Pharmacogenet Genomics 2006; 16:801-8. [PMID: 17047488 DOI: 10.1097/01.fpc.0000230422.50962.91] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Our aim was to investigate possible effects of sequence variations in ABCC2, encoding the multidrug resistance-associated protein 2 (MRP2), on the pharmacokinetics of the MRP2 substrate pravastatin. METHODS Deoxyribonucleic acid samples of 41 healthy volunteers, in whom SLCO1B1 single nucleotide polymorphisms (SNPs) and haplotypes had previously been found to be associated with increased plasma pravastatin concentrations, were investigated. Each study participant had ingested a single 40-mg dose of pravastatin followed by blood sampling for pharmacokinetic characterization in standardized conditions. The exons, exon-intron boundaries, promoter region and 3'-untranslated region of the ABCC2 gene of six individuals with the highest and six individuals with the lowest pravastatin area under the plasma concentration-time curve (AUC) values were sequenced. RESULTS Of the 26 sequence variations found, the synonymous c.1446C>G SNP was observed heterozygously in three (50%) of the six individuals with a low pravastatin AUC and in none (0%) of the six individuals with a high AUC (P=0.06 for allele frequency). The remaining 29 participants were then also genotyped for c.1446C>G, but none of them carried the SNP. In addition, the effect of c.1446C>G on MRP2 mRNA expression was investigated in 93 human liver samples. A multiple linear regression analysis in the 41 participants with pravastatin pharmacokinetic data indicated that the ABCC2 c.1446C>G SNP and the previously identified SLCO1B1 haplotype *17 were independent predictors of the AUC0-12 and Cmax of pravastatin (r=32 and 29%, respectively) (P<0.01). In the participants heterozygous for the ABCC2 c.1446C>G SNP (n=3), who were not carriers of the SLCO1B1*17 haplotype, the AUC0-12 and Cmax of pravastatin were 67 and 68% lower than in those carrying neither the SLCO1B1*17 haplotype nor the ABCC2 c.1446C>G SNP (n=35) (P<0.05). MRP2 mRNA expression was 95% higher in livers with the c.1446CG genotype (n=7) than in those with the c.1446CC genotype (n=86) (P<0.05). CONCLUSIONS These results support the idea that the ABCC2 c.1446C>G SNP is associated with reduced systemic exposure to pravastatin as a consequence of increased MRP2 expression. The underlying mechanism may involve either a modulating effect of the SNP on mRNA stability or linkage to other polymorphism(s) acting at the transcriptional level.
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Affiliation(s)
- Mikko Niemi
- Department of Clinical Pharmacology, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland.
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162
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Stieger B, Meier Y, Meier PJ. The bile salt export pump. Pflugers Arch 2006; 453:611-20. [PMID: 17051391 DOI: 10.1007/s00424-006-0152-8] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Accepted: 08/08/2006] [Indexed: 12/20/2022]
Abstract
Canalicular secretion of bile salts mediated by the bile salt export pump Bsep constitutes the major driving force for the generation of bile flow. Bsep is a member of the B-family of the super family of ATP-binding cassette transporters and is classified as ABCB11. Bsep has a narrow substrate specificity, which is largely restricted to bile salts. Bsep is extensively regulated at the transcriptional and posttranscriptional level, which directly modulates canalicular bile formation. Pathophysiological alterations of Bsep by either inherited mutations or acquired processes such as inhibition by drugs or disease-related down regulation may lead to a wide spectrum of mild to severe forms of liver disease. Furthermore, many genetic variants of Bsep are known, some of which potentially render individuals susceptible to acquired forms of liver disease.
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Affiliation(s)
- Bruno Stieger
- Department of Medicine, Institute of Clinical Pharmacology and Toxicology, University Hospital, Zürich, Switzerland.
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163
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Abstract
Drug-induced liver injury is an important clinical problem with significant morbidity and mortality. Whereas for most hepatocellular forms of drug-induced hepatic injury the underlying pathophysiological mechanism is poorly understood, there is increasing evidence that cholestatic forms of drug-induced liver damage result from a drug- or metabolite-mediated inhibition of hepatobiliary transporter systems. In addition to their key role in determining hepatic drug exposure and clearance, the coordinated action of these transport systems is essential for bile formation and the biliary secretion of cholephilic compounds and xenobiotics. Any drug-mediated functional disturbance of these processes can lead to an intracellular accumulation of potentially harmful bile constituents and result in the development of cholestatic liver cell damage. In addition to direct drug-mediated inhibition of hepatocellular transport, function of these transporters can be altered by pre-existing hepatic disease and genetic factors, which contribute to the development of drug-induced cholestasis in susceptible individuals. This review summarizes current knowledge about the function of hepatobiliary uptake and efflux systems and discusses factors that might predispose to drug-induced cholestasis.
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Affiliation(s)
- Christiane Pauli-Magnus
- Division of Clinical Pharmacology and Toxicology, University Hospital Zurich, Zurich, Switzerland.
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