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Marwa KJ, Kapesa A, Kamugisha E, Swedberg G. The Influence of Cytochrome P450 Polymorphisms on Pharmacokinetic Profiles and Treatment Outcomes Among Malaria Patients in Sub-Saharan Africa: A Systematic Review. Pharmgenomics Pers Med 2023; 16:449-461. [PMID: 37223718 PMCID: PMC10202199 DOI: 10.2147/pgpm.s379945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 04/24/2023] [Indexed: 05/25/2023] Open
Abstract
Background Sub-Saharan Africa (SSA) population is genetically diverse and heterogenous thus variability in drug response among individuals is predicted to be high. Cytochrome P450 (CYP450) polymorphisms is a major source of variability in drug response. This systematic review presents the influence of CYP450 single nucleotide polymorphisms (SNPs), particularly CYP3A4*1B, CYP2B6*6 and CYP3A5*3 on antimalarial drug plasma concentrations, efficacy and safety in SSA populations. Methods Searching for relevant studies was done through Google Scholar, Cochrane Central Register of controlled trials (CENTRAL), PubMed, Medline, LILACS, and EMBASE online data bases. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were used. Two independent reviewers extracted data from the studies. Results Thirteen studies reporting the influence of CYP450 SNPs on plasma concentrations, efficacy and safety were included in the final data synthesis. CYP3A4*1B, CYP3A5*5, CYP2B6*6 and CYP2C8*2 did not affect antimalarial drug plasma concentration significantly. There was no difference in treatment outcomes between malaria patients with variant alleles and those with wild type alleles. Conclusion This review reports lack of influence of CYP3A4*1B, CYP3A5*3, CYP2C8*3 and CYP2B6*6 SNPs on PK profiles, efficacy and safety in SSA among P. falciparum malaria patients.
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Affiliation(s)
- Karol J Marwa
- Department of Pharmacology, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
| | - Anthony Kapesa
- Department of Community Medicine, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
| | - Erasmus Kamugisha
- Department of Biochemistry, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
| | - Göte Swedberg
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
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2
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Ahire D, Kruger L, Sharma S, Mettu VS, Basit A, Prasad B. Quantitative Proteomics in Translational Absorption, Distribution, Metabolism, and Excretion and Precision Medicine. Pharmacol Rev 2022; 74:769-796. [PMID: 35738681 DOI: 10.1124/pharmrev.121.000449] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A reliable translation of in vitro and preclinical data on drug absorption, distribution, metabolism, and excretion (ADME) to humans is important for safe and effective drug development. Precision medicine that is expected to provide the right clinical dose for the right patient at the right time requires a comprehensive understanding of population factors affecting drug disposition and response. Characterization of drug-metabolizing enzymes and transporters for the protein abundance and their interindividual as well as differential tissue and cross-species variabilities is important for translational ADME and precision medicine. This review first provides a brief overview of quantitative proteomics principles including liquid chromatography-tandem mass spectrometry tools, data acquisition approaches, proteomics sample preparation techniques, and quality controls for ensuring rigor and reproducibility in protein quantification data. Then, potential applications of quantitative proteomics in the translation of in vitro and preclinical data as well as prediction of interindividual variability are discussed in detail with tabulated examples. The applications of quantitative proteomics data in physiologically based pharmacokinetic modeling for ADME prediction are discussed with representative case examples. Finally, various considerations for reliable quantitative proteomics analysis for translational ADME and precision medicine and the future directions are discussed. SIGNIFICANCE STATEMENT: Quantitative proteomics analysis of drug-metabolizing enzymes and transporters in humans and preclinical species provides key physiological information that assists in the translation of in vitro and preclinical data to humans. This review provides the principles and applications of quantitative proteomics in characterizing in vitro, ex vivo, and preclinical models for translational research and interindividual variability prediction. Integration of these data into physiologically based pharmacokinetic modeling is proving to be critical for safe, effective, timely, and cost-effective drug development.
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Affiliation(s)
- Deepak Ahire
- Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Laken Kruger
- Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Sheena Sharma
- Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Vijaya Saradhi Mettu
- Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Abdul Basit
- Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Bhagwat Prasad
- Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington
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Langlois AW, El-Boraie A, Fukunaga K, Mushiroda T, Kubo M, Lerman C, Knight J, Scherer SE, Chenoweth MJ, Tyndale RF. Accuracy and applications of sequencing and genotyping approaches for CYP2A6 and homologous genes. Pharmacogenet Genomics 2022; 32:159-172. [PMID: 35190513 PMCID: PMC9081136 DOI: 10.1097/fpc.0000000000000466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES We evaluated multiple genotyping/sequencing approaches in a homologous region of chromosome 19, and investigated associations of two common 3'-UTR CYP2A6 variants with activity in vivo. METHODS Individuals (n = 1704) of European and African ancestry were phenotyped for the nicotine metabolite ratio (NMR), an index of CYP2A6 activity, and genotyped/sequenced using deep amplicon exon sequencing, SNP array, genotype imputation and targeted capture sequencing. Amplicon exon sequencing was the gold standard to which other methods were compared within-individual for CYP2A6, CYP2A7, CYP2A13, and CYP2B6 exons to identify highly discordant positions. Linear regression models evaluated the association of CYP2A6*1B and rs8192733 genotypes (coded additively) with logNMR. RESULTS All approaches were ≤2.6% discordant with the gold standard; discordant calls were concentrated at few positions. Fifteen positions were discordant in >10% of individuals, with 12 appearing in regions of high identity between homologous genes (e.g. CYP2A6 and CYP2A7). For six, allele frequencies in our study and online databases were discrepant, suggesting errors in online sources. In the European-ancestry group (n = 935), CYP2A6*1B and rs8192733 were associated with logNMR (P < 0.001). A combined model found main effects of both variants on increasing logNMR. Similar trends were found in those of African ancestry (n = 506). CONCLUSION Multiple genotyping/sequencing approaches used in this chromosome 19 region contain genotyping/sequencing errors, as do online databases. Gene-specific primers and SNP array probes must consider gene homology; short-read sequencing of related genes in a single reaction should be avoided. Using improved sequencing approaches, we characterized two gain-of-function 3'-UTR variants, including the relatively understudied rs8192733.
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Affiliation(s)
- Alec W.R. Langlois
- Department of Pharmacology & Toxicology, University of Toronto; 1 King’s College Circle, Toronto, ON, M5S 1A8, Canada. Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health 100 Stokes Street, Toronto, ON, M6J 1H4, Canada
| | - Ahmed El-Boraie
- Department of Pharmacology & Toxicology, University of Toronto; 1 King’s College Circle, Toronto, ON, M5S 1A8, Canada. Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health 100 Stokes Street, Toronto, ON, M6J 1H4, Canada
| | - Koya Fukunaga
- Center for Integrative Medical Sciences, RIKEN; 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Taisei Mushiroda
- Center for Integrative Medical Sciences, RIKEN; 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Michiaki Kubo
- Center for Integrative Medical Sciences, RIKEN; 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Caryn Lerman
- Department of Psychiatry and USC Norris Comprehensive Cancer Center, University of Southern California, 1441 Eastlake Avenue, Cancer Center, Los Angeles, CA, 90089, United States
| | - Jo Knight
- Data Science Institute and Lancaster University Medical School, Lancaster, UK
- Department of Psychiatry, University of Toronto; 250 College Street, Toronto, ON, M5T 1R8, Canada
| | - Steven E. Scherer
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX
| | - Meghan J. Chenoweth
- Department of Pharmacology & Toxicology, University of Toronto; 1 King’s College Circle, Toronto, ON, M5S 1A8, Canada. Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health 100 Stokes Street, Toronto, ON, M6J 1H4, Canada
| | - Rachel F. Tyndale
- Department of Pharmacology & Toxicology, University of Toronto; 1 King’s College Circle, Toronto, ON, M5S 1A8, Canada. Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health 100 Stokes Street, Toronto, ON, M6J 1H4, Canada
- Department of Psychiatry, University of Toronto; 250 College Street, Toronto, ON, M5T 1R8, Canada
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Le Foll B, Piper ME, Fowler CD, Tonstad S, Bierut L, Lu L, Jha P, Hall WD. Tobacco and nicotine use. Nat Rev Dis Primers 2022; 8:19. [PMID: 35332148 DOI: 10.1038/s41572-022-00346-w] [Citation(s) in RCA: 56] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/07/2022] [Indexed: 01/04/2023]
Abstract
Tobacco smoking is a major determinant of preventable morbidity and mortality worldwide. More than a billion people smoke, and without major increases in cessation, at least half will die prematurely from tobacco-related complications. In addition, people who smoke have a significant reduction in their quality of life. Neurobiological findings have identified the mechanisms by which nicotine in tobacco affects the brain reward system and causes addiction. These brain changes contribute to the maintenance of nicotine or tobacco use despite knowledge of its negative consequences, a hallmark of addiction. Effective approaches to screen, prevent and treat tobacco use can be widely implemented to limit tobacco's effect on individuals and society. The effectiveness of psychosocial and pharmacological interventions in helping people quit smoking has been demonstrated. As the majority of people who smoke ultimately relapse, it is important to enhance the reach of available interventions and to continue to develop novel interventions. These efforts associated with innovative policy regulations (aimed at reducing nicotine content or eliminating tobacco products) have the potential to reduce the prevalence of tobacco and nicotine use and their enormous adverse impact on population health.
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Affiliation(s)
- Bernard Le Foll
- Translational Addiction Research Laboratory, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada.
- Departments of Family and Community Medicine, Psychiatry, Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada.
| | - Megan E Piper
- Department of Medicine, University of Wisconsin, Madison, WI, USA
- University of Wisconsin Center for Tobacco Research and Intervention, Madison, WI, USA
| | - Christie D Fowler
- Department of Neurobiology and Behaviour, University of California Irvine, Irvine, CA, USA
| | - Serena Tonstad
- Section for Preventive Cardiology, Department of Endocrinology, Morbid Obesity and Preventive Medicine, Oslo University Hospital, Oslo, Norway
| | - Laura Bierut
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Lin Lu
- Institute of Mental Health, Peking University Sixth Hospital, Peking University, Beijing, China
- National Institute on Drug Dependence, Peking University Health Science Center, Beijing, China
| | - Prabhat Jha
- Centre for Global Health Research, Unity Health Toronto, University of Toronto, Toronto, Ontario, Canada
| | - Wayne D Hall
- National Centre for Youth Substance Use Research, The University of Queensland, St Lucia, Queensland, Australia
- Queensland Alliance for Environmental Health Sciences, The University of Queensland, Woolloongabba, Queensland, Australia
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Yadav VK, Katiyar T, Ruwali M, Yadav S, Singh S, Hadi R, Bhatt MLB, Parmar D. Polymorphism in cytochrome P4502A6 reduces the risk to head and neck cancer and modifies the treatment outcome. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2021; 62:502-511. [PMID: 34655463 DOI: 10.1002/em.22466] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 09/26/2021] [Accepted: 10/11/2021] [Indexed: 06/13/2023]
Abstract
The present case-control study consisting of 1300 cases of head and neck squamous cell carcinoma (HNSCC) and the equal number of controls aimed to investigate the association of functionally important polymorphisms in cytochrome P4502A6 (CYP2A6*1B, CYP2A6*4C, CYP2A6*9-rs28399433) with HNSCC and the treatment response in cases receiving a combination of chemotherapy/radiotherapy (CT/RT). A significant decrease in risk to HNSCC was observed in the cases with deletion (CYP2A6*4B and CYP2A6*4C) or reduced activity genotypes (CYP2A6*9) of CYP2A6. This risk to HNSCC was further reduced significantly in tobacco users among the cases when compared to nontobacco users among the cases. The risk was also reduced to a slightly greater extent in alcohol users among the cases when compared to nonalcohol users among the cases. In contrast with decreased risk to HNSCC, almost half of the cases with variant genotypes of CYP2A6 (CYP2A6*1A/*4C+*1B/*4C+*4C/*4C and *9/*9) did not respond to the treatment. Likewise, the survival rate in cases receiving the treatment, after 55 months of follow-up was significantly lower in cases with deletion (6.3%) or reduced activity (11.9%) allele than in the cases with common alleles (41%). The present study has shown that CYP2A6 polymorphism significantly reduces the risk to HNSCC. Our data further suggested that CYP2A6 polymorphism may worsen the treatment outcome in the cases receiving CT/RT.
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Affiliation(s)
- Vinay Kumar Yadav
- System Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research, Lucknow, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Tridiv Katiyar
- System Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research, Lucknow, India
| | - Munindra Ruwali
- Faculty of Science, Engineering And Technology, Amity University, Gurgaon, India
| | - Sanjay Yadav
- All India Institute of Medical Sciences, Raebareli, India
| | - Sudhir Singh
- Department of Radiotherapy, King George's Medical University, Lucknow, India
| | - Rahat Hadi
- Department of Radiation Oncology, Dr Ram Manohar Lohia Institute of Medical Sciences, Lucknow, India
| | | | - Devendra Parmar
- System Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research, Lucknow, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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Schaefer KR, Avey JP, Todd MR, Beans JA, Dillard DA, Shireman LM, Thornton TA, Tyndale RF, Thummel KE, Robinson RF, Claw KG. Nicotine metabolism and its association with CYP2A6 genotype among Indigenous people in Alaska who smoke. Clin Transl Sci 2021; 14:2474-2486. [PMID: 34520119 PMCID: PMC8604252 DOI: 10.1111/cts.13115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 06/14/2021] [Accepted: 06/21/2021] [Indexed: 11/29/2022] Open
Abstract
Prevalence of smoking is higher in Alaska Native and American Indian (ANAI) populations living in Alaska than the general US population. Genetic factors contribute to smoking and cessation rates. The objective of this study was to compare CYP2A6 genetic variation and CYP2A6 enzyme activity toward nicotine in an ANAI population. ANAI (N = 151) people trying to quit smoking were recruited. DNA samples were genotyped for CYP2A6 variants *1X2A, *1B, *2, *4, *9, *10, *12, and *35. Multiple nicotine metabolites were measured in plasma and urine samples, including cotinine and 3′‐hydroxycotinine used to determine CYP2A6 activity (e.g., nicotine metabolite ratio [NMR]). We calculated summary statistics for all of the genotypes and metabolites and assigned CYP2A6 activity scores based on known information. We studied the association of CYP2A6 variants with the NMR and smoking histories. The overall frequency of the CYP2A6*1B gain of function allele was high in the ANAI versus non‐ANAI populations in other studies. Both *4 null and *9 decrease of function alleles had frequencies similar to previous studies of ANAI populations. In a multivariate analysis, the genotype‐inferred CYP2A6 activity score was associated with both plasma and urine NMR (p value = 8.56E‐08 and 4.08E‐13, respectively). Plasma NMR was also associated with duration of smoking (p value < 0.01) but not urinary total nicotine equivalents uncorrected for creatinine (TNE9uc) or biological sex. Urine NMR was significantly associated (p value < 0.01) with TNE9uc. Variation in NMR in this ANAI population is explained in part by CYP2A6 genetic variation.
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Affiliation(s)
- Krista R Schaefer
- Research Department, Southcentral Foundation, Anchorage, Alaska, USA
| | - Jaedon P Avey
- Research Department, Southcentral Foundation, Anchorage, Alaska, USA
| | - Michael R Todd
- Research Department, Southcentral Foundation, Anchorage, Alaska, USA
| | - Julie A Beans
- Research Department, Southcentral Foundation, Anchorage, Alaska, USA
| | - Denise A Dillard
- Research Department, Southcentral Foundation, Anchorage, Alaska, USA
| | - Laura M Shireman
- Departments of Pharmaceutics, University of Washington, Seattle, Washington, USA
| | | | - Rachel F Tyndale
- Departments of Pharmacology and Toxicology, and Psychiatry, University of Toronto, Toronto, Ontario, Canada.,Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Kenneth E Thummel
- Departments of Pharmaceutics, University of Washington, Seattle, Washington, USA
| | - Renee F Robinson
- College of Pharmacy, Idaho State University, Pocatello, Idaho, USA.,University of Alaska Anchorage, Anchorage, Alaska, USA
| | - Katrina G Claw
- Division of Biomedical Informatics and Personalized Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.,Colorado Center for Personalized Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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7
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Claw KG, Beans JA, Lee SB, Avey JP, Stapleton PA, Scherer SE, El-Boraie A, Tyndale RF, Nickerson DA, Dillard DA, Thummel KE, Robinson RF. Pharmacogenomics of Nicotine Metabolism: Novel CYP2A6 and CYP2B6 Genetic Variation Patterns in Alaska Native and American Indian Populations. Nicotine Tob Res 2020; 22:910-918. [PMID: 31241144 PMCID: PMC7249913 DOI: 10.1093/ntr/ntz105] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 06/21/2019] [Indexed: 11/12/2022]
Abstract
INTRODUCTION Alaska Native and American Indian (AN/AI) populations have higher tobacco use prevalence than other ethnic/racial groups. Pharmacogenetic testing to tailor tobacco cessation treatment may improve cessation rates. This study characterized polymorphic variations among AN/AI people in genes associated with metabolism of nicotine and drugs used for tobacco cessation. METHODS Recruitment of AN/AI individuals represented six subgroups, five geographic subgroups throughout Alaska and a subgroup comprised of AIs from the lower 48 states living in Alaska. We sequenced the CYP2A6 and CYP2B6 genes to identify known and novel gain, reduced, and loss-of-function alleles, including structural variation (eg, gene deletions, duplications, and hybridizations). RESULTS Variant allele frequencies differed substantially between AN/AI subgroups. The gene deletion CYP2A6*4 and reduced function CYP2A6*9 alleles were found at high frequency in Northern/Western subgroups and in Lower 48/Interior subgroups, respectively. The reduced function CYP2B6*6 allele was observed in all subgroups and a novel, predicted reduced function CYP2B6 variant was found at relatively high frequency in the Southeastern subgroup. CONCLUSIONS Diverse CYP2A6 and CYP2B6 variation among the subgroups highlight the need for comprehensive pharmacogenetic testing to guide tobacco cessation therapy for AN/AI populations. IMPLICATIONS Nicotine metabolism is largely determined by CYP2A6 genotype, and variation in CYP2A6 activity has altered the treatment success in other populations. These findings suggest pharmacogenetic-guided smoking cessation drug treatment could provide benefit to this unique population seeking tobacco cessation therapy.
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Affiliation(s)
- Katrina G Claw
- Department of Pharmaceutics, University of Washington, Seattle, WA
| | - Julie A Beans
- Research Department, Southcentral Foundation, Anchorage, AK
| | - Seung-Been Lee
- Department of Genome Sciences, University of Washington, Seattle, WA
| | - Jaedon P Avey
- Research Department, Southcentral Foundation, Anchorage, AK
| | - Patricia A Stapleton
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA
| | - Steven E Scherer
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX
| | - Ahmed El-Boraie
- Departments of Pharmacology and Toxicology, and Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Rachel F Tyndale
- Departments of Pharmacology and Toxicology, and Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
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8
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Chen YC, Fowler JP, Wang J, Watson CJW, Sherafat Y, Staben A, Lazarus P, Denton TT, Fowler CD. The Novel CYP2A6 Inhibitor, DLCI-1, Decreases Nicotine Self-Administration in Mice. J Pharmacol Exp Ther 2019; 372:21-29. [PMID: 31628204 DOI: 10.1124/jpet.119.260653] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 10/16/2019] [Indexed: 01/24/2023] Open
Abstract
During tobacco and e-cigarette use, nicotine is mainly metabolized in the human liver by cytochrome P450 2A6 (CYP2A6). Given that a slower CYP2A6 metabolism has been associated with less vulnerability to develop nicotine dependence, the current studies sought to validate a novel CYP2A6 inhibitor, (5-(4-ethylpyridin-3-yl)thiophen-2-yl)methanamine (DLCI-1), for its effects on intravenous nicotine self-administration. Male and female mice were trained to self-administer nicotine across daily sessions. Once stable responding was achieved, DLCI-1 or vehicle control was administered prior to nicotine sessions. We found that the lower 25 mg/kg and moderate 50 mg/kg doses of DLCI-1 induced a significant decrease in nicotine intake for both males and females. DLCI-1 was further shown to be more effective than a moderate 1 mg/kg dose of bupropion on reducing nicotine intake and did not exert the adverse behavioral effects found with a high 75 mg/kg dose of bupropion. Although mice treated with DLCI-1 self-administered significantly less nicotine, similar nicotine-mediated behavioral effects on locomotion were observed. Together, along with the analysis of nicotine metabolites during self-administration, these findings support the contention that blocking hepatic nicotine metabolism would allow for similar activation of nicotinic acetylcholine receptors at lower nicotine doses. Moreover, these effects of DLCI-1 were specific to nicotine self-administration, as DLCI-1 did not result in any behavioral changes during food self-administration. Taken together, these studies validate DLCI-1 as a novel compound to decrease nicotine consumption, which may thereby promote tobacco and nicotine product cessation. SIGNIFICANCE STATEMENT: Current pharmacological approaches for nicotine and tobacco cessation have only been able to achieve limited efficaciousness in promoting long-term abstinence. In this work, we characterize the effects of a novel compound, (5-(4-ethylpyridin-3-yl)thiophen-2-yl)methanamine (DLCI-1), which inhibits the main enzyme that metabolizes nicotine, and we report a significant decrease in intravenous nicotine self-administration in male and female mice, supporting the potential of DLCI-1 as a novel tobacco cessation pharmacotherapeutic.
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Affiliation(s)
- Yen-Chu Chen
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, California (Y.-C.C., J.P.F., Y.S., A.S., C.D.F.); and Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.W., C.J.W.W., P.L., T.T.D.)
| | - James P Fowler
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, California (Y.-C.C., J.P.F., Y.S., A.S., C.D.F.); and Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.W., C.J.W.W., P.L., T.T.D.)
| | - Jing Wang
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, California (Y.-C.C., J.P.F., Y.S., A.S., C.D.F.); and Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.W., C.J.W.W., P.L., T.T.D.)
| | - Christy J W Watson
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, California (Y.-C.C., J.P.F., Y.S., A.S., C.D.F.); and Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.W., C.J.W.W., P.L., T.T.D.)
| | - Yasmine Sherafat
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, California (Y.-C.C., J.P.F., Y.S., A.S., C.D.F.); and Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.W., C.J.W.W., P.L., T.T.D.)
| | - Andres Staben
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, California (Y.-C.C., J.P.F., Y.S., A.S., C.D.F.); and Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.W., C.J.W.W., P.L., T.T.D.)
| | - Philip Lazarus
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, California (Y.-C.C., J.P.F., Y.S., A.S., C.D.F.); and Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.W., C.J.W.W., P.L., T.T.D.)
| | - Travis T Denton
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, California (Y.-C.C., J.P.F., Y.S., A.S., C.D.F.); and Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.W., C.J.W.W., P.L., T.T.D.)
| | - Christie D Fowler
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, California (Y.-C.C., J.P.F., Y.S., A.S., C.D.F.); and Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.W., C.J.W.W., P.L., T.T.D.)
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9
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Hammad HM, Imraish A, Azab B, Best AM, Khader YS, Zihlif M. Associations of CYP2A6 Gene Polymorphism with Smoking Status Among Jordanians: Gender-Related Differences. Curr Drug Metab 2019; 20:765-770. [PMID: 31453782 DOI: 10.2174/1389200220666190827161112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 08/14/2019] [Accepted: 08/16/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND Cytochrome P450 2A6 enzyme (CYP2A6), an essential hepatic enzyme involved in the metabolism of drugs, is responsible for a major metabolic pathway of nicotine. Variation in the activity of polymorphic CYP2A6 alleles has been implicated in inter-individual differences in nicotine metabolism. AIMS The objective of the current study was to assess the association between the smoking status and the cytochrome P450 2A6 enzyme (CYP2A6) genotype in Jordanians. METHODS In the current study, 218 (117 Male and 101 female) healthy unrelated Jordanian volunteers were recruited. CYP2A6*1B, CYP2A6*4 and CYP2A6*9 were determined and correlated with subject smoking status. RESULTS *1A/*1A was the most common genetic polymorphism in the overall study population, with no significant frequency differences between smokers and non-smokers. When the population was divided according to gender, only male smokers showed a significant correlation between genotype and smoking status. Considering the CYP2A6*9 genotype, the results showed differences in distribution between smokers and non-smokers, but only women showed a significant association between CYP2A6*9 allele genotype and smoking status. CONCLUSION The results of this study show that there is a significant association between CYP2A6*9 genotype and smoking status. They also show that CYP2A6 genotype is significantly influenced by gender.
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Affiliation(s)
- Hana M Hammad
- Department of Biological Sciences, School of Science, The University of Jordan, Amman, Jordan
| | - Amer Imraish
- Department of Biological Sciences, School of Science, The University of Jordan, Amman, Jordan
| | - Belal Azab
- Department of Pathology, School of Medicine, The University of Jordan, Amman, Jordan
| | - Al M Best
- Virginia Commonwealth University, Richmond VA, United States
| | - Yousef S Khader
- Department of Community Medicine, Public Health and Family Medicine, Faculty of Medicine, Jordan University of Science & Technology, Irbid, Jordan
| | - Malek Zihlif
- Department of Pharmacology, School of Medicine, The University of Jordan, Amman, Jordan
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Hasan F, Katiyar T, Maurya SS, Yadav V, Yadav S, Pandey R, Mehrotra D, Hadi R, Singh S, Bhatt ML, Parmar D. Similarities in mRNA expression of peripheral blood drug metabolizing enzymes and cancer marker genes with biopsy samples of head and neck cancer patients. Biomarkers 2019; 24:574-583. [PMID: 31002268 DOI: 10.1080/1354750x.2019.1609090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Purpose: To develop peripheral blood mRNA expression profiles of drug metabolizing enzymes (DMEs) as a surrogate to monitor tobacco induced head and neck squamous cell carcinoma (HNSCC), attempts were made to investigate (i) similarities in alterations with the cancer marker genes in biopsy samples and (ii) if alterations similar to that seen in biopsy samples are reflected in peripheral blood. Methods: Total RNA from eight soft gingival tissues and eight biopsy samples of HNSCC patients and total DNA and RNA from blood of healthy controls (n = 150) and HNSCC patients (n = 150) was processed for expression and genotyping studies. Blood from patients receiving chemo-radiotherapy was processed for follow-up study. Results: qRT-PCR revealed significant increase in mRNA expression of DMEs in biopsy and blood samples of HNSCC patients when compared to controls. Similar alterations were observed in cancer marker genes in these samples. Patients with variant genotypes of DMEs showed greater magnitude of alterations in mRNA expression when compared to wild type controls. Responders of chemo-radiotherapy showed significant decline in induction of mRNA expression of DMEs and cancer marker genes Conclusions: The data suggest that peripheral blood expression profiles could be used to monitor tobacco-induced HNSCC as well as the treatment response.
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Affiliation(s)
- Feza Hasan
- a Developmental Toxicology Laboratory, System Toxicology & Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR) , Lucknow , India.,b School of Dental Sciences, Department of Biochemistry, Babu Banarsi Das University , Lucknow , India
| | - Tridiv Katiyar
- a Developmental Toxicology Laboratory, System Toxicology & Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR) , Lucknow , India.,b School of Dental Sciences, Department of Biochemistry, Babu Banarsi Das University , Lucknow , India
| | - Shailendra S Maurya
- a Developmental Toxicology Laboratory, System Toxicology & Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR) , Lucknow , India
| | - Vinay Yadav
- a Developmental Toxicology Laboratory, System Toxicology & Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR) , Lucknow , India
| | - Sanjay Yadav
- a Developmental Toxicology Laboratory, System Toxicology & Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR) , Lucknow , India
| | - Rahul Pandey
- c Department of Radiotherapy & Department of Oral and Maxillofacial Surgery, King George's Medical University , Lucknow , India
| | - Divya Mehrotra
- c Department of Radiotherapy & Department of Oral and Maxillofacial Surgery, King George's Medical University , Lucknow , India
| | - Rahat Hadi
- d Department of Radiation Oncology, Dr. Ram Manohar Lohia Institute of Medical Sciences , Lucknow , India
| | - Sudhir Singh
- c Department of Radiotherapy & Department of Oral and Maxillofacial Surgery, King George's Medical University , Lucknow , India
| | - Madan L Bhatt
- c Department of Radiotherapy & Department of Oral and Maxillofacial Surgery, King George's Medical University , Lucknow , India
| | - Devendra Parmar
- a Developmental Toxicology Laboratory, System Toxicology & Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR) , Lucknow , India
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Xia R, Zhu X, Chen Z, He Y, Kang L, Yuan D, Jin T, Wang L. Genetic polymorphisms of the drug-metabolizing enzyme cytochrome P450 2A6 in a Tibetan Chinese population. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2018; 11:5024-5033. [PMID: 31949579 PMCID: PMC6962933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 04/05/2017] [Indexed: 06/10/2023]
Abstract
Detection of CYP2A6 variant alleles, and knowledge about their allelic frequency in Tibetan ethnic groups, is important to establish the clinical relevance of screening for these polymorphisms to optimize pharmacotherapy. We used DNA sequencing to investigate the promoter, exons and surrounding introns, and untranslated region of the CYP2A6 gene in 100 unrelated healthy Tibetan individuals. We also used SIFT and PolyPhen-2 to predict the protein function of the novel non-synonymous mutation in CYP2A6 coding regions. We found 33 different CYP2A6 polymorphisms in the Tibetan population, five of which were novel: -98T > G in promoter region, 1886C > A, 5640C > A, 5827G > T in intron and missense mutation 5011G > A in exon 7. We identified six CYP2A6 alleles (*1, *10, *11, *14, *15 and *18), with a wide frequency range from 1.00% to 86.50% in the population. We also detected six CYP2A6 genotypes, with a wide frequency range from 2.00% to 73.00%. Three of which (*1/*10, *1/*11 and *1/*18) lead to decreased enzyme activity. This study provided new information regarding CYP2A6genetic polymorphisms in Tibetan individuals, which will greatly facilitate studies on the relevance of pharmacogenetics for CYP2A6 with respect to disease risk and to the pharmacokinetics and pharmacodynamics of many drugs.
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Affiliation(s)
- Ridong Xia
- Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Disease of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory of High Altitude Environment and Genes Related to Diseases of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory for Basic Life Science Research of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
| | - Xikai Zhu
- Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Disease of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory of High Altitude Environment and Genes Related to Diseases of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory for Basic Life Science Research of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
| | - Zhengshuai Chen
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of EducationXi’an, Shaanxi 710069, China
| | - Yongjun He
- Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Disease of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory of High Altitude Environment and Genes Related to Diseases of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory for Basic Life Science Research of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
| | - Longli Kang
- Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Disease of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory of High Altitude Environment and Genes Related to Diseases of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory for Basic Life Science Research of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
| | - Dongya Yuan
- Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Disease of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory of High Altitude Environment and Genes Related to Diseases of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory for Basic Life Science Research of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
| | - Tianbo Jin
- Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Disease of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory of High Altitude Environment and Genes Related to Diseases of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory for Basic Life Science Research of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of EducationXi’an, Shaanxi 710069, China
| | - Li Wang
- Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Disease of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory of High Altitude Environment and Genes Related to Diseases of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
- Key Laboratory for Basic Life Science Research of Tibet Autonomous Region, School of Medicine, Xizang Minzu UniversityXianyang, Shaanxi, China
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Tanner JA, Tyndale RF. Variation in CYP2A6 Activity and Personalized Medicine. J Pers Med 2017; 7:jpm7040018. [PMID: 29194389 PMCID: PMC5748630 DOI: 10.3390/jpm7040018] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 11/17/2017] [Accepted: 11/27/2017] [Indexed: 12/16/2022] Open
Abstract
The cytochrome P450 2A6 (CYP2A6) enzyme metabolizes several clinically relevant substrates, including nicotine-the primary psychoactive component in cigarette smoke. The gene that encodes the CYP2A6 enzyme is highly polymorphic, resulting in extensive interindividual variation in CYP2A6 enzyme activity and the rate of metabolism of nicotine and other CYP2A6 substrates including cotinine, tegafur, letrozole, efavirenz, valproic acid, pilocarpine, artemisinin, artesunate, SM-12502, caffeine, and tyrosol. CYP2A6 expression and activity are also impacted by non-genetic factors, including induction or inhibition by pharmacological, endogenous, and dietary substances, as well as age-related changes, or interactions with other hepatic enzymes, co-enzymes, and co-factors. As variation in CYP2A6 activity is associated with smoking behavior, smoking cessation, tobacco-related lung cancer risk, and with altered metabolism and resulting clinical responses for several therapeutics, CYP2A6 expression and enzyme activity is an important clinical consideration. This review will discuss sources of variation in CYP2A6 enzyme activity, with a focus on the impact of CYP2A6 genetic variation on metabolism of the CYP2A6 substrates.
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Affiliation(s)
- Julie-Anne Tanner
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, ON M5T 1R8, Canada.
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Rachel F Tyndale
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, ON M5T 1R8, Canada.
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S 1A8, Canada.
- Department of Psychiatry, University of Toronto, Toronto, ON M5T 1R8, Canada.
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13
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Variation in CYP2A6 and nicotine metabolism among two American Indian tribal groups differing in smoking patterns and risk for tobacco-related cancer. Pharmacogenet Genomics 2017; 27:169-178. [PMID: 28181923 DOI: 10.1097/fpc.0000000000000271] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The Northern Plains (NP) and Southwest (SW) American Indian populations differ in their smoking patterns and lung cancer incidence. We aimed to compare CYP2A6 genetic variation and CYP2A6 enzyme activity (representative of the rate of nicotine metabolism) between the two tribal populations as these have previously been associated with differences in smoking, quitting, and lung cancer risk. PARTICIPANTS AND METHODS American Indians (N=636) were recruited from two different tribal populations (NP in South Dakota, SW in Arizona) as part of a study carried out as part of the Collaborative to Improve Native Cancer Outcomes P50 Project. A questionnaire assessed smoking-related traits and demographics. Participants were genotyped for CYP2A6 genetic variants *1B, *2, *4, *7, *9, *12, *17, and *35. Plasma and/or saliva samples were used to measure nicotine's metabolites cotinine and 3'-hydroxycotinine and determine CYP2A6 activity (3'-hydroxycotinine/cotinine, i.e. the nicotine metabolite ratio, NMR). RESULTS The overall frequency of genetically reduced nicotine metabolizers, those with CYP2A6 decrease-of-function or loss-of-function alleles, was lower in the NP compared with the SW (P=0.0006). The CYP2A6 genotype was associated with NMR in both tribal groups (NP, P<0.0001; SW, P=0.04). Notably, the rate of nicotine metabolism was higher in NP compared with SW smokers (P=0.03), and in comparison with other ethnic groups in the USA. Of the variables studied, the CYP2A6 genotype was the only variable to significantly independently influence NMR among smokers in both tribal populations (NP, P<0.001; SW, P=0.05). CONCLUSION Unique CYP2A6 allelic patterns and rates of nicotine metabolism among these American Indian populations suggest different risks for smoking, and tobacco-related disease.
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14
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Ou WC, Huang YC, Huang CL, Lin MH, Chen YC, Chen YJ, Liu CN, Chen MC, Huang CS, Chen PL. Interaction between cytochrome P450 2A6 and Catechol-O-Methyltransferase genes and their association with smoking risk in young men. Behav Brain Funct 2017; 13:8. [PMID: 28472995 PMCID: PMC5418756 DOI: 10.1186/s12993-017-0127-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 04/26/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Although some effects of gene-gene interactions on nicotine-dopamine metabolism for smoking behavior have been reported, polymorphisms of cytochrome P450 (CYP) 2A6 and catechol-O-methyltransferase (COMT) have not been studied together to determine their effects on smokers. The aim of this study was to investigate the effects of the interaction between the CYP 2A6 and COMT genes on smoking behavior in young Taiwanese men. RESULTS A self-report questionnaire regarding smoking status was administered to 500 young men. Polymorphisms of the CYP 2A6 and COMT genes as well as urinary nicotine and urinary cotinine levels were determined. The odds ratio for starting smoking was significantly lower in subjects carrying a CYP2A6 low activity/variant COMT rs4680 genotype than in those possessing a CYP2A6 wild-type/variant COMT rs4680 genotype (0.44, 95% confidence interval = 0.19-0.98, P = 0.043). Comparisons of Fagerstrom Test for Nicotine Dependence (FTND), Physiological Cigarette Dependence Scale (PCDS), and Cigarette Withdrawal symptoms (CWS-21) among the smokers with different CYP2A6/COMT polymorphisms were not significantly different. The adjusted urinary nicotine concentrations were not significantly different between the two groups carrying different genotypes. The adjusted urinary cotinine level was significantly different between the COMT rs4680 wild-type group and COMT rs4680 variant group [92.46 ng/μL vs. 118.24 ng/μL (median value), P = 0.041] and between the COMT rs4680 wild-type/COMT rs165599 variant group and COMT rs4680 variant/COMT rs165599 variant group (97.10 ng/μL vs. 122.18 ng/μL, P = 0.022). CONCLUSIONS These findings suggest that a single nucleotide polymorphism (rs4680) of the COMT gene and the interaction between the CYP 2A6 and COMT genes affect smoking status in young Taiwanese men.
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Affiliation(s)
- Wei-Chih Ou
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, No. 666 Buzih Road, Beitun District, Taichung City, 40601, Taiwan
| | - Yi-Chin Huang
- Division of Infectious Diseases, Jen-Ai Hospital, Taichung, Taiwan
| | - Chih-Ling Huang
- Department of Nursing, Chang Jung Christian University, Tainan, Taiwan
| | - Min-Hsuan Lin
- Administration Center for Research and Education, Changhua Christian Hospital, Changhua, Taiwan
| | - Yi-Chun Chen
- Administration Center for Research and Education, Changhua Christian Hospital, Changhua, Taiwan
| | - Yi-Ju Chen
- Company Limited of Ditech Enterprise, Taipei, Taiwan
| | - Chen-Nu Liu
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, No. 666 Buzih Road, Beitun District, Taichung City, 40601, Taiwan
| | - Mei-Chih Chen
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, No. 666 Buzih Road, Beitun District, Taichung City, 40601, Taiwan
| | - Ching-Shan Huang
- Administration Center for Research and Education, Changhua Christian Hospital, Changhua, Taiwan.
| | - Pei-Lain Chen
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, No. 666 Buzih Road, Beitun District, Taichung City, 40601, Taiwan.
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Wassenaar CA, Zhou Q, Tyndale RF. CYP2A6 genotyping methods and strategies using real-time and end point PCR platforms. Pharmacogenomics 2015; 17:147-62. [PMID: 26670214 DOI: 10.2217/pgs.15.156] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
CYP2A6 genotyping is of clinical importance--CYP2A6 gene variants influence nicotine metabolism and are associated with nicotine dependence, cigarettes per day, smoking cessation and the risk for tobacco-associated cancers. CYP2A6 gene variants also influence the metabolism of therapeutic drugs, such as the anticancer agents, tegafur and letrozole. Over the years, CYP2A6 genotyping methods have evolved to incorporate novel gene variants and to circumvent genotyping errors resulting from the high degree of homology between CYP2A6 and neighboring CYP2A genes. Herein, CYP2A6 genotyping strategies are described for commonly genotyped functionally significant alleles including SNPs, small insertions/deletions and more complex structural variants. The methods presented utilize higher throughput SYBR green real-time PCR technology in addition to standard thermocycling.
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Affiliation(s)
- Catherine A Wassenaar
- Department of Pharmacology & Toxicology, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8 ON, Canada
| | - Qian Zhou
- Department of Pharmacology & Toxicology, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8 ON, Canada
| | - Rachel F Tyndale
- Campbell Family Mental Health Research Institute, Centre for Addiction & Mental Health (CAMH), Departments of Pharmacology & Toxicology & Psychiatry, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8 ON, Canada
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De Souza EST, De Araújo LF, De Alencar DO, Dos Santos SEB, Silva WA, Ferreira CA, Baddini-Martinez J. Does ethnic ancestry play a role in smoking? AN ACAD BRAS CIENC 2015; 87:447-53. [PMID: 25651157 DOI: 10.1590/0001-3765201520140187] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 09/08/2014] [Indexed: 11/22/2022] Open
Abstract
The higher proportion of smokers among Black people in Brazil has been attributed to socioeconomic disparities, but genetic factors could also contribute for this finding. This study aimed at investigating associations between smoking status with genetically defined ethnic ancestry and socioeconomic features in Brazilians. Blood samples were collected from 448 volunteers (66.7% male; age: 37.1 ± 11.4 years) classified as current smokers (CS: 60.9%), former smokers (FS: 8.9%) and never smokers (NS: 30.1%). Individual interethnic admixtures were determined using a 48 insertion-deletion polymorphisms ancestry-informative-marker panel. CS showed a lower amount of European ancestry than NS (0.837 ± 0.243 X 0.883 ± 0.194, p ≤ 0.05) and FS (0.837 ± 0.243 X 0.864 ± 0.230, p ≤ 0.05), and a higher proportion of African Sub-Saharan ancestry than FS (0.128 ± 0.222 X 0.07 ± 0.174, p ≤ 0.05) and NS (0.128 ± 0.222 X 0.085 ± 0.178, p ≤ 0.05). NS reported a higher number of years in school than CS (11.2 ± 3.7 X 8.9 ± 3.8, p ≤ 0.001). CS were less common in economic Class A (30%) and more common in Class B (56.8%). In multivariate analysis, only lower number of school years and lower economic class were associated with higher chances for CS. The use of genetic molecular markers for characterizing ethnic background confirmed that socioeconomic disparities are the main determinants of higher smoking rates among Blacks in Brazil.
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Affiliation(s)
- Elisa S T De Souza
- Departamento de Clínica Médica, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - Luiza F De Araújo
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - Dayse O De Alencar
- Departamento de Patologia, Universidade Federal do Pará, Belém, PA, Brasil
| | | | - Wilson A Silva
- Departamento de Clínica Médica, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - Cristiane A Ferreira
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - José Baddini-Martinez
- Departamento de Clínica Médica, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
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Phompradit P, Muhamad P, Cheoymang A, Na-Bangchang K. Preliminary investigation of the contribution of CYP2A6, CYP2B6, and UGT1A9 polymorphisms on artesunate-mefloquine treatment response in Burmese patients with Plasmodium falciparum malaria. Am J Trop Med Hyg 2014; 91:361-6. [PMID: 24891466 DOI: 10.4269/ajtmh.13-0531] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
CYP2A6, CYP2B6, and UGT1A9 genetic polymorphisms and treatment response after a three-day course of artesunate-mefloquine was investigated in 71 Burmese patients with uncomplicated Plasmodium falciparum malaria. Results provide evidence for the possible link between CYP2A6 and CYP2B6 polymorphisms and plasma concentrations of artesunate/dihydroartemisinin and treatment response. In one patient who had the CYP2A6*1A/*4C genotype (decreased enzyme activity), plasma concentration of artesunate at one hour appeared to be higher, and the concentration of dihydroartemisinin was lower than for those carrying other genotypes (415 versus 320 ng/mL). The proportion of patients with adequate clinical and parasitologic response who had the CYP2B6*9/*9 genotype (mutant genotype) was significantly lower compared with those with late parasitologic failure (14.0% versus 19.0%). Confirmation through a larger study in various malaria-endemic areas is required before a definite conclusion on the role of genetic polymorphisms of these drug-metabolizing enzymes on treatment response after artesunate-based combination therapy can be made.
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Affiliation(s)
- Papichaya Phompradit
- Chulabhorn International College of Medicine, and Thailand Center of Excellence on Drug Discovery and Development Thammasat University (Rangsit Campus), Patumthani, Thailand; Mae Sot General Hospital, Mae Sot District, Tak Province, Thailand
| | - Poonuch Muhamad
- Chulabhorn International College of Medicine, and Thailand Center of Excellence on Drug Discovery and Development Thammasat University (Rangsit Campus), Patumthani, Thailand; Mae Sot General Hospital, Mae Sot District, Tak Province, Thailand
| | - Anurak Cheoymang
- Chulabhorn International College of Medicine, and Thailand Center of Excellence on Drug Discovery and Development Thammasat University (Rangsit Campus), Patumthani, Thailand; Mae Sot General Hospital, Mae Sot District, Tak Province, Thailand
| | - Kesara Na-Bangchang
- Chulabhorn International College of Medicine, and Thailand Center of Excellence on Drug Discovery and Development Thammasat University (Rangsit Campus), Patumthani, Thailand; Mae Sot General Hospital, Mae Sot District, Tak Province, Thailand
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Aklillu E, Djordjevic N, Carrillo JA, Makonnen E, Bertilsson L, Ingelman-Sundberg M. High CYP2A6 enzyme activity as measured by a caffeine test and unique distribution of CYP2A6 variant alleles in Ethiopian population. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2013; 18:446-53. [PMID: 24380444 DOI: 10.1089/omi.2013.0140] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
CYP2A6 metabolizes clinically relevant drugs, including antiretroviral and antimalarial drugs of major public health importance for the African populations. CYP2A6 genotype-phenotype relationship in African populations, and implications of geographic differences on enzyme activity, remain to be investigated. We evaluated the influence of CYP2A6 genotype, geographical differences, gender, and cigarette smoking on enzyme activity, using caffeine as a probe in 100 healthy unrelated Ethiopians living in Ethiopia, and 72 living in Sweden. CYP2A6 phenotype was estimated by urinary 1,7-dimethyluric acid (17U)/1,7-dimethylxanthine or paraxanthine (17X) ratio. The frequencies of CYP2A6*1B, *1D, *2, *4, *9, and *1x2 in Ethiopians were 31.3, 29.4, 0.6, 0.6, 2.8, and 0.3%, respectively. The overall mean±SD for log 17U/17X was 0.12±0.24 and coefficient of variation 199%. No significant difference in the mean log 17U/17X ratio between Ethiopians living in Sweden versus Ethiopia was observed. Analysis of variance revealed CYP2A6 genotype (p=0.04, F=2.01) but not geographical differences, sex, or cigarette smoking as predictors of CYP2A6 activity. Importantly, the median (interquartile range) of 17U/17X ratio in Ethiopians 1.35 (0.99 to 1.84) was 3- and 11-fold higher than the previously reported value in Swedes 0.52 (0.27 to 1.00) and Koreans 0.13 (0.0 to 0.35), respectively (Djordjevic et al., 2013). Taken together, we report here the relevance of CYP2A6 genotype for enzyme activity in this Ethiopian sample, as well as high CYP2A6 activity and unique distribution of the CYP2A6 variant alleles in Ethiopians as compared other populations described hitherto. Because Omics biomarker research is rapidly accelerating in Africa, CYP2A6 pharmacogenetics and clinical pharmacology observations reported herein for the Ethiopian populations have clinical and biological importance to plan for future rational therapeutics efforts in the African continent as well as therapeutics as a global science.
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Affiliation(s)
- Eleni Aklillu
- 1 Division of Clinical Pharmacology, Department of Laboratory Medicine, Karolinska University Hospital , Karolinska Institutet, Stockholm, Sweden
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Nicotine aversion: Neurobiological mechanisms and relevance to tobacco dependence vulnerability. Neuropharmacology 2013; 76 Pt B:533-44. [PMID: 24055497 DOI: 10.1016/j.neuropharm.2013.09.008] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 09/04/2013] [Accepted: 09/05/2013] [Indexed: 11/22/2022]
Abstract
Nicotine stimulates brain reward circuitries, most prominently the mesocorticolimbic dopamine system, and this action plays a critical in establishing and maintaining the tobacco smoking habit. Compounds that attenuate nicotine reward are considered promising therapeutic candidates for tobacco dependence, but many of these agents have other actions that limit their potential utility. Nicotine is also highly noxious, particularly at higher doses, and aversive reactions to nicotine after initial exposure can decrease the likelihood of developing a tobacco habit in many first time smokers. Nevertheless, relatively little is known about the mechanisms of nicotine aversion. The purpose of this review is to present recent new insights into the neurobiological mechanisms that regulate avoidance of nicotine. First, the role of the mesocorticolimbic system, so often associated with nicotine reward, in regulating nicotine aversion is highlighted. Second, genetic variation that modifies noxious responses to nicotine and thereby influences vulnerability to tobacco dependence, in particular variation in the CHRNA5-CHRNA3-CHRNB4 nicotinic acetylcholine receptor (nAChR) subunit gene cluster, will be discussed. Third, the role of the habenular complex in nicotine aversion, primarily medial habenular projections to the interpeduncular nucleus (IPN) but also lateral habenular projections to rostromedial tegmental nucleus (RMTg) and ventral tegmental area (VTA) are reviewed. Forth, brain circuits that are enriched in nAChRs, but whose role in nicotine avoidance has not yet been assessed, will be identified. Finally, the feasibility of developing novel therapeutic agents for tobacco dependence that act not by blocking nicotine reward but by enhancing nicotine avoidance will be considered. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.
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A compensatory effect upon splicing results in normal function of the CYP2A6*14 allele. Pharmacogenet Genomics 2013; 23:107-16. [PMID: 23292114 DOI: 10.1097/fpc.0b013e32835caf7d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A synonymous variant in the first exon of CYP2A6, rs1137115 (51G>A), defines the common reference allele CYP2A6*1A, and is associated with lower mRNA expression and slower in-vivo nicotine metabolism. Another common allele, CYP2A6*14, differs from CYP2A6*1A by a single variant, rs28399435 (86G>A, S29N). However, CYP2A6*14 shows in-vivo activity comparable with that of full-function alleles, and significantly higher than CYP2A6*1A. rs1137115A is predicted to create an exonic splicing suppressor site overlapping an exonic splicing enhancer (ESE) site in the first exon of CYP2A6, whereas rs28399435A is predicted to strengthen another adjacent ESE, potentially compensating for rs1137115A. Using an allelic expression assay to assess cDNAs produced from rs1137115 heterozygous liver biopsy samples, lower expression of the CYP2A6*1A allele is confirmed while CYP2A6*14 expression is found to be indistinguishable from that of rs1137115G alleles. Quantitative PCR assays to determine the relative abundance of spliced and unspliced or partially spliced CYP2A6 mRNAs in liver biopsy samples show that *1A/*1A homozygotes have a significantly lower ratio, due to both a reduction in spliced forms and an increase in unspliced or partially spliced CYP2A6. These results show the importance of common genetic variants that effect exonic splicing suppressor and ESEs to explain human variation regarding clinically-relevant phenotypes.
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Cytochrome P450 2A6 deletion polymorphism and risk of lung cancer: a meta-analysis. Mol Biol Rep 2013; 40:5255-9. [PMID: 23733493 DOI: 10.1007/s11033-013-2625-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 04/30/2013] [Indexed: 10/26/2022]
Abstract
Previous studies concerning the association between cytochrome P450 2A6 (CYP2A6) deletion polymorphism and lung cancer risk provided controversial results. To clarify the precise association, a meta-analysis was performed. The electronic databases PubMed, Chinese Biomedical Database and Chinese National Knowledge Infrastructure Database were searched for case-control studies last updated on June 3, 2012 that investigated CYP2A6 deletion polymorphism and lung cancer risk. The odds ratio (OR) and its respective 95 % confidence interval (95 % CI) were used to measure the strength of association by means of a genetic model free approach. A total of 8 studies including 2,607 cases and 2,595 controls met the inclusion criteria and were subjected to the final analysis. The most appropriate co-dominant model was adopted. Overall, we found that CYP2A6 *1/*1 genotype was associated with an increased risk of lung cancer relative to *4/*4 genotype (OR = 2.65, 95 % CI: 1.84-3.81, P < 0.001). Significant association was also detected among Asians. Publication bias was absent in this meta-analysis. Therefore, our data suggested that the presence of the CYP2A6 *1/*1 might be associated with an increased lung cancer risk, especially for Asians. Further studies well-designed among different ethnicity populations are required.
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PharmGKB summary: very important pharmacogene information for cytochrome P-450, family 2, subfamily A, polypeptide 6. Pharmacogenet Genomics 2013; 22:695-708. [PMID: 22547082 DOI: 10.1097/fpc.0b013e3283540217] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Lung cancer risk in relation to nicotinic acetylcholine receptor, CYP2A6 and CYP1A1 genotypes in the Bangladeshi population. Clin Chim Acta 2013. [DOI: 10.1016/j.cca.2012.11.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Djordjevic N, Carrillo JA, van den Broek MP, Kishikawa J, Roh HK, Bertilsson L, Aklillu E. Comparisons of CYP2A6 Genotype and Enzyme Activity between Swedes and Koreans. Drug Metab Pharmacokinet 2013; 28:93-7. [DOI: 10.2133/dmpk.dmpk-12-rg-029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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CYP2A6 and CYP2B6 genetic variation and its association with nicotine metabolism in South Western Alaska Native people. Pharmacogenet Genomics 2012; 22:429-40. [PMID: 22569203 DOI: 10.1097/fpc.0b013e3283527c1c] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
OBJECTIVES Alaska Native (AN) people have a high prevalence of tobacco use and associated morbidity and mortality when compared with the general USA population. Variations in the CYP2A6 and CYP2B6 genes, encoding enzymes responsible for nicotine metabolic inactivation and procarcinogen activation, have not been characterized in AN and may contribute toward the increased risk. METHODS AN people (n=400) residing in the Bristol Bay region of South Western Alaska were recruited for a cross-sectional study on tobacco use. They were genotyped for CYP2A6*1X2A, *1X2B, *1B, *2, *4, *7, *8, *9, *10, *12, *17, *35 and CYP2B6*4, *6, *9 and provided plasma and urine samples for the measurement of nicotine and metabolites. RESULTS CYP2A6 and CYP2B6 variant frequencies among the AN Yupik people (n=361) were significantly different from those in other ethnicities. Nicotine metabolism [as measured by the plasma and urinary ratio of metabolites trans-3'-hydroxycotinine to cotinine (3HC/COT)] was significantly associated with CYP2A6 (P<0.001), but not CYP2B6 genotype (P=0.95) when controlling for known covariates. It was noteworthy that the plasma 3HC/COT ratios were high in the entire Yupik people, and among the Yupik CYP2A6 wild-type participants, they were substantially higher than those in previously characterized racial/ethnic groups (P<0.001 vs. Caucasians and African Americans). CONCLUSION Yupik AN people have a unique CYP2A6 genetic profile that associated strongly with in-vivo nicotine metabolism. More rapid CYP2A6-mediated nicotine and nitrosamine metabolism in the Yupik people may modulate the risk of tobacco-related diseases.
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Abstract
The Twin Research Registry (TRR) at SRI International is a community-based registry of twins established in 1995 by advertising in local media, mainly on radio stations and in newspapers. As of August 2012, there are 3,120 same- and opposite-sex twins enrolled; 86% are 18 years of age or older (mean age 44.9 years, SD 16.9 years) and 14% less than 18 years of age (mean age 8.9 years, SD 4.5); 67% are female, and 62% are self-reported monozygotic (MZ). More than 1,375 twins have participated in studies over the last 15 years in collaboration with the University of California Medical Center in San Francisco, the University of Texas MD Anderson Cancer Center, and the Stanford University School of Medicine. Each twin completes a registration form with basic demographic information either online at the TRR Web site or during a telephone interview. Contact is maintained with members by means of annual newsletters and birthday cards. The managers of the TRR protect the confidentiality of twin data with established policies; no information is given to other researchers without prior permission from the twins; and all methods and procedures are reviewed by an Institutional Review Board. Phenotypes studied thus far include those related to nicotine metabolism, mutagen sensitivity, pain response before and after administration of an opioid, and a variety of immunological responses to environmental exposures, including second-hand smoke and vaccination for seasonal influenza virus and Varicella zoster virus. Twins in the TRR have participated in studies of complex, clinically relevant phenotypes that would not be feasible to measure in larger samples.
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Systematic review of the relationship between the 3-hydroxycotinine/cotinine ratio and cigarette dependence. Psychopharmacology (Berl) 2011; 218:313-22. [PMID: 21597990 DOI: 10.1007/s00213-011-2341-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Accepted: 04/30/2011] [Indexed: 10/18/2022]
Abstract
RATIONALE Individual differences in the rate of nicotine metabolism (RNM) could be related to dependence and success in stopping smoking. A range of studies have examined RNM measured by the ratio of trans-3'-hydroxycotinine and cotinine in body fluids (the ratio). A systematic review of this literature is needed to draw conclusions and identify gaps in evidence. OBJECTIVE The aim of this study is to review evidence on the association of the ratio to cigarette dependence and its role in individual tailoring of smoking cessation pharmacotherapy. RESULTS We reviewed 27 studies of the ratio related to its reliability, validity, and relationship to dependence. The ratio is a reasonably accurate proxy for RNM. There is little evidence that the ratio is related to questionnaire measures of dependence, though the existing data are limited and the ratio has been linked to smoking at night and to some aspects of smoking topography. The ratio is also only weakly associated with cigarette consumption. Its relationship to the severity of withdrawal symptoms seems also weak at best, but limited data exist. One study suggests the ratio predicts outcome of unaided quitting. Importantly, the ratio seems to predict responses both to NRT and bupropion, and thus could guide pharmacotherapy. CONCLUSIONS The evidence that the ratio is related to smoking behaviours and to cigarette dependence is limited, but the ratio seems to influence treatment response to two stop smoking medications. Further studies of the relationship between the ratio and cigarette dependence and trials of ratio-guided pharmacotherapy are needed.
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The contribution of common CYP2A6 alleles to variation in nicotine metabolism among European-Americans. Pharmacogenet Genomics 2011; 21:403-16. [PMID: 21597399 DOI: 10.1097/fpc.0b013e328346e8c0] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To study the association between cytochrome P450 2A6 (CYP2A6) genotype and metabolism of nicotine to cotinine, identify functional polymorphisms, and develop a predictive genetic model of nicotine metabolism. METHODS The conversion of deuterated (D2)-nicotine to D2-cotinine was quantified in 189 European-Americans and the contribution of CYP2A6 genotype to variability in first-pass nicotine metabolism was assessed. Specifically, (i) single time point measures of D2-cotinine/(D2-cotinine+D2-nicotine) after oral administration were used as a metric of CYP2A6 activity; (ii) the impact of CYP2A6 haplotype was treated as acting multiplicatively; (iii) parameter estimates were calculated for all haplotypes in the subject pool, defined by a set of polymorphisms previously reported to affect function, including gene copy number; and (iv) a minimum number of predictive polymorphisms were justified to be included in the model based on statistical evidence of differences between haplotypes. RESULTS The final model includes seven polymorphisms and fits the phenotype, 30-min after D2-nicotine oral administration, with R=0.719. The predictive power of the model is robust: parameter estimates calculated in men (n=89) predict the phenotype in women (n=100) with R=0.758 and vice versa with R=0.617; estimates calculated in current smokers (n=102) predict the phenotype in former-smokers (n=86) with R=0.690 and vice versa with R=0.703. Comparisons of haplotypes also demonstrate that CYP2A6*12 is a loss-of-function allele indistinguishable from CYP2A6*4 and CYP2A6*2 and that the CYP2A6*1B 5'-untranslated region conversion has negligible impact on metabolism. After controlling for CYP2A6 genotype, modest associations were found between increased metabolism and both female sex (P=4.8×10) and current smoking (P=0.02). CONCLUSION Among European-Americans, seven polymorphisms in the CYP2A6 gene explain the majority of variability in the metabolism of nicotine to cotinine after oral administration. Parameters determined from this in-vivo experiment can be used to predict nicotine metabolism based on CYP2A6 genotype.
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Yusof W, Hua GS. Gene, ethnic and gender influences predisposition of adverse drug reactions to artesunate among Malaysians. Toxicol Mech Methods 2011; 22:184-92. [PMID: 22003869 DOI: 10.3109/15376516.2011.623331] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
CONTEXT Artesunate (AS) and amodiaquine (AQ) are two prodrugs widely used as antimalarial agents and are metabolized by the CYP P450 2A6 (CYP 2A6) and CYP P450 2C8 (CYP 2C8) enzymes, respectively. OBJECTIVE In this study, we aim to investigate the association of both genes on AS and AQ's tolerabilities in the hope of identifying a pharmacogenetic approach that could be useful in prediction and prevention of adverse drug reactions (ADRs) among Malaysian population. MATERIALS AND METHODS In this randomized crossover study, loose and AS/AQ formulations were administered to normal healthy volunteers (n = 24) over two study phases. The drugs' tolerabilities (incidence of facial flushing, giddiness, headache, nausea, abdominal discomfort, progression of liver enzymes and neutrophil counts) were compared between the two treatment arms. Volunteers were also genotyped for the CYP2C8 and CYP2A6 variants. RESULTS The frequency of the CYP2A6*1B, CYP2A6*4, CYP2A6*8 and CYP2A6*9 alleles were 54.2%, 16.7%, 4.2% and 10.4%, respectively. No mutations for CYP2C8 gene were, however, detected. Most (96%) of the subjects were of the Malay ethnicity. Subjects having the CYP2A6*1B variants responsible for ultra rapid metabolism of AS suffered a significantly higher incidence of ADRs. DISCUSSION Our study is the first to report that CYP2A6 genotyping influences AS's ADR. Gender also plays a role where females reported more incidences of nausea (p < 0.05). CONCLUSION It is concluded that genetic polymorphisms of CYP2A6 as well as gender influence the side effect profiles of subjects receiving AS among this Malaysian population.
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Affiliation(s)
- Wardah Yusof
- Department of Pharmacology, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
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Wang H, Bian T, Liu D, Jin T, Chen Y, Lin A, Chen C. Association analysis of CYP2A6 genotypes and haplotypes with 5-fluorouracil formation from tegafur in human liver microsomes. Pharmacogenomics 2011; 12:481-92. [PMID: 21521021 DOI: 10.2217/pgs.10.202] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AIM Tegafur is primarily converted to 5-fluorouracil (5-FU) by CYP2A6 in the human liver to exert its antitumor effect. Our objective was to comprehensively investigate the effects of CYP2A6 genetic polymorphisms on tegafur bioactivation activity. MATERIALS & METHODS Using a set of over 45 Chinese livers, the association between CYP2A6 genetic variations and 5-FU formation rates from tegafur, as well as CYP2A6 mRNA and protein levels, was determined. RESULTS A total of 20 polymorphic variants and 20 haplotypes of CYP2A6 were identified. From genotype/haplotype-phenotype association tests, we demonstrated that CYP2A6*4 was the main allele responsible for the decreased 5-FU formation from tegafur and CYP2A6 expression in this population. By contrast, haplotype 14 (a novel CYP2A6*1B allele) was associated with increased microsomal 5-FU formation activity and CYP2A6 expression, and this may be attributed to the combined effects of three single variants (g.22C>T, g.1620T>C and a gene conversion in the 3´-UTR) included in this haplotype. CONCLUSION We concluded that CYP2A6*4 and the novel CYP2A6*1B variant were the major genetic determinants of interindividual variability in 5-FU formation from tegafur in Chinese livers. Original submitted 2 November 2010; Revision submitted 3 December 2010.
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Affiliation(s)
- Huijuan Wang
- National Engineering Research Center for Miniaturized Detection Systems, School of Life Sciences, Northwest University, 229 North Taibai Road, Xi'an 710069, China
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Liu T, David SP, Tyndale RF, Wang H, Zhou Q, Ding P, He YH, Yu XQ, Chen W, Crump C, Wen XZ, Chen WQ. Associations of CYP2A6 genotype with smoking behaviors in southern China. Addiction 2011; 106:985-94. [PMID: 21205058 PMCID: PMC3074015 DOI: 10.1111/j.1360-0443.2010.03353.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIMS To investigate the association of CYP2A6 genetic polymorphisms with smoking-related phenotypes in Chinese smokers. DESIGN Case-only genetic association study. SETTING Southern China. PARTICIPANTS A total of 1328 Han Chinese smokers who participated in a community-based chronic disease screening project in Guangzhou and Zhuhai from 2006 to 2007. MEASUREMENTS All participants answered a structured questionnaire about socio-demographic status and smoking behaviors and informative alleles were genotyped for the cytochrome P450 2A6 (CYP2A6) gene (CYP2A6*4,*5,*7,*9 and *10). FINDINGS The frequencies of CYP2A6*4, *5, *7, *9 and *10 alleles were 8.5, 1.2, 6.3, 13.5 and 2.4%, which corresponded to 48.9, 15.4, 24.2 and 11.5% of participants being classified as normal, intermediate, slow and poor metabolizers, respectively. Multivariate analyses in male smokers demonstrated that compared with normal metabolizers, poor metabolizers reported smoking fewer cigarettes per day [adjusted odds ratio (OR) = 0.49; 95% confidence interval (CI): 0.32-0.76], started smoking regularly later in life (adjusted OR = 1.55; 95% CI: 1.06-2.26) and, among former smokers, reported smoking for a shorter duration prior to quitting (adjusted OR = 0.33; 95% CI: 0.12-0.94). However, poor metabolizers were less likely to quit smoking and remain abstinent than normal metabolizers (adjusted OR = 0.54; 95% CI: 0.34-0.86). CONCLUSIONS Reduced metabolism function of cytochrome P450 2A6 in smokers appears to be associated with fewer cigarettes smoked, later initiation of smoking regularly, shorter smoking duration and lower likelihood of smoking cessation.
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Affiliation(s)
- Tao Liu
- Department of Biostatistics and Epidemiology, School of Public Health, Sun Yat-Sen University, 74, Zhongshan Road 2, 510080, Guangzhou, China
| | - Sean P. David
- Center for Education in Family & Community Medicine and the Division of Family & Community Medicine, Stanford University, 1215 Welch Road, Modular G, Stanford, CA 94305, USA, SRI International, 333 Ravenswood Ave, Menlo Park, CA 943025, USA, Center for Primary Care & Prevention and the Department of Family Medicine, Brown Alpert Medical School, 111 Brewster Street, Pawtucket, RI 02860
| | - Rachel F. Tyndale
- The Center for Addiction and Mental Health and the Departments of Psychiatry, Pharmacology and Toxicology, University of Toronto, Canada M5S 1A8
| | - Hui Wang
- Department of Biostatistics and Epidemiology, School of Public Health, Sun Yat-Sen University, 74, Zhongshan Road 2, 510080, Guangzhou, China
| | - Qian Zhou
- The Center for Addiction and Mental Health and the Departments of Psychiatry, Pharmacology and Toxicology, University of Toronto, Canada M5S 1A8
| | - Peng Ding
- Department of Biostatistics and Epidemiology, School of Public Health, Sun Yat-Sen University, 74, Zhongshan Road 2, 510080, Guangzhou, China
| | - Yan-Hui He
- Department of Biostatistics and Epidemiology, School of Public Health, Sun Yat-Sen University, 74, Zhongshan Road 2, 510080, Guangzhou, China
| | - Xue-Qing Yu
- Department of Nephrology, The First Affiliated Hospital of Sun Yat-Sen University, 58, Zhongshan Road 2, 510080, Guangzhou, China
| | - Wei Chen
- Department of Nephrology, The First Affiliated Hospital of Sun Yat-Sen University, 58, Zhongshan Road 2, 510080, Guangzhou, China
| | - Casey Crump
- Center for Education in Family & Community Medicine and the Division of Family & Community Medicine, Stanford University, 1215 Welch Road, Modular G, Stanford, CA 94305, USA
| | - Xiao-Zhong Wen
- Department of Community Health, Brown University, Providence, RI, USA
| | - Wei-Qing Chen
- Department of Biostatistics and Epidemiology, School of Public Health, Sun Yat-Sen University, 74, Zhongshan Road 2, 510080, Guangzhou, China,To whom correspondence should be addressed. Tel: +8620 87332199; Fax: +8620 87330446, (Wei-Qing Chen)
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Williams JM, Gandhi KK, Benowitz NL. Carbamazepine but not valproate induces CYP2A6 activity in smokers with mental illness. Cancer Epidemiol Biomarkers Prev 2010; 19:2582-9. [PMID: 20719908 DOI: 10.1158/1055-9965.epi-10-0384] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Antiepileptic drugs (AED) are being increasingly used in the management of serious mental illness, but their effects on nicotine metabolism have not been studied. METHODS This study investigated the effects of three AEDs (carbamazepine, oxcarbazepine, and valproic acid) on nicotine and nicotine metabolite levels in 149 smokers with schizophrenia and bipolar disorder who participated in an afternoon blood draw for nicotine, cotinine, and 3'-hydroxycotinine (3HC). The ratio of 3HC to cotinine was calculated as a marker of CYP2A6 metabolic activity. Among the participants, 8 smokers were taking carbamazepine, 6 were taking oxcarbazepine, and 40 were taking valproic acid. RESULTS The 3HC/cotinine ratio was significantly higher in individuals taking carbamazepine or oxcarbazepine (combined, n = 14) versus those not taking either (mean 0.993 versus 0.503; P < 0.001). The cotinine/cigarette per day ratio was significantly lower in individuals taking carbamazepine or oxcarbazepine. The 3HC/cotinine ratios were also significantly higher in the subgroup of individuals taking carbamazepine (n = 8) versus those not taking it. There were no significant differences in nicotine or cotinine levels or 3HC/cotinine ratios in individuals taking valproic acid versus those not taking it. We conducted backward stepwise linear regression models to identify predictors of the log transformed 3HC/cotinine ratios. Taking carbamazepine and number of cigarettes smoked per day were significant determinants of log 3HC/cotinine. CONCLUSIONS Carbamazepine likely induces hepatic metabolism via CYP2A6 and is associated with increased 3HC/cotinine ratios. IMPACT Increased nicotine metabolism in individuals using AED has implications for increased smoking behavior and exposure to more tobacco toxins, which warrants further study.
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Affiliation(s)
- Jill M Williams
- UMDNJ-Robert Wood Johnson Medical School, 317 George Street, Suite 105, New Brunswick, NJ 08901-2008, USA.
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Mwenifumbo JC, Zhou Q, Benowitz NL, Sellers EM, Tyndale RF. New CYP2A6 gene deletion and conversion variants in a population of Black African descent. Pharmacogenomics 2010; 11:189-98. [PMID: 20136358 PMCID: PMC2922202 DOI: 10.2217/pgs.09.144] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AIMS Cytochrome P450 2A6 (CYP2A6) is a human enzyme best known for metabolizing nicotine and nitrosamine precarcinogens. Our aim was to discover and characterize new CYP2A6 alleles in a population of Black African descent. MATERIALS & METHODS We used cloning, sequencing and genotyping of genomic DNA to discover new variants, and in vivo nicotine pharmacokinetic phenotyping to characterize the functional effect of the new alleles. RESULTS Four new CYP2A6 alleles, CYP2A6*4G, *4H, *1B4 and *1L, were discovered and characterized in a population of Black African descent. The two new deletion alleles, CYP2A6*4G and *4H, are distinguished by different crossover junctions at 7.9 and 7.8 kb downstream of the CYP2A6 +1ATG start site, respectively; their combined allele frequency is 1.6%. The new gene conversion alleles, CYP2A6*1B4 and CYP2A6*1L, contain 27 and 10 bp of CYP2A7 sequence in the CYP2A6 3 -flanking region, respectively; their combined allele frequency is 7.3%. CYP2A6*4 appears to associate with lower CYP2A6 activity in vivo, while CYP2A6*1L does not; however, CYP2A6*1L confounds genotyping assays that use the 2A6R3 and 2A6R4 primers. CONCLUSION As new variants are discovered, the relationships between CYP2A6 genotype, nicotine metabolism, smoking behaviors and tobacco-related cancer risk will be further clarified.
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Affiliation(s)
- Jill C Mwenifumbo
- Department of Pharmacology, Room 4326 Medical Sciences Building, 1 King's College Circle, CAMH & University of Toronto, Toronto, ON M5S 1A8, Canada
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Kortmann GL, Dobler CJ, Bizarro L, Bau CHD. Pharmacogenetics of smoking cessation therapy. Am J Med Genet B Neuropsychiatr Genet 2010; 153B:17-28. [PMID: 19475569 DOI: 10.1002/ajmg.b.30978] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Nicotine dependence is a major health problem, with a large amount of smoking-related premature deaths and disabilities. The dependence mechanism of nicotine is especially complex and is under strong genetic influence. Smoking cessation is associated with substantial health benefits. Evidence from animal and human studies suggests that genetic polymorphisms influencing pharmacokinetics and pharmacodynamics of nicotine may have great potential for aiding smoking treatment. There are more than 30 association studies and one genome-wide association study (GWAS) between genetic polymorphisms and smoking cessation following nicotine replacement therapy (NRT) and/or bupropion therapy. However, only a few candidate genes or regions were analyzed more than twice and even these genes require additional investigations in different therapeutic schemes. There are a growing number of new pharmacologic options that have not been pharmacogenetically assessed according to published literature. In addition, molecular genetics studies are needed to assess the functional mechanisms of some putative association results. Taken together, the preliminary findings are promising but raise the need for new studies with adequate sample sizes and adjustment for several potential confounding factors frequently neglected, such as comorbidity and sociodemographic factors. The current state of the art in the field encourages an optimist view that personalized treatment approaches may become possible. However, the current scientific evidence still does not support the use of pharmacogenetic tests in routine smoking cessation therapy.
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Affiliation(s)
- Gustavo L Kortmann
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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Ruwali M, Pant MC, Shah PP, Mishra BN, Parmar D. Polymorphism in cytochrome P450 2A6 and glutathione S-transferase P1 modifies head and neck cancer risk and treatment outcome. Mutat Res 2009; 669:36-41. [PMID: 19406142 DOI: 10.1016/j.mrfmmm.2009.04.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Revised: 03/04/2009] [Accepted: 04/17/2009] [Indexed: 05/27/2023]
Abstract
A case control study was carried out to investigate the association of functionally important polymorphism in cytochrome P450 2A6 (CYP2A6) and glutathione S-transferase P1 (GSTP1) genes with head and neck squamous cell carcinoma (HNSCC) and treatment response in cases receiving a combination of chemo-radiotherapy. The study group consisted of 350 males suffering from HNSCC and an equal number of male controls. Multivariate logistic regression analysis revealed statistically significant decrease in risk to HNSCC in cases with variant genotypes (CYP2A6*1B and CYP2A6*4C) of CYP2A6 (OR: 0.78; 95% CI: 0.43-1.22; P=0.04) or GSTP1 (OR: 0.71; 95% CI: 0.51-1.00; P=0.05). The risk associated with these variant genotypes was found to be further decreased in cases carrying a combination of variant genotypes of CYP2A6 and GSTP1 (OR: 0.40; 95% CI: 0.25-0.65; P=0.00). A similar decrease in risk was observed in cases with variant genotypes of CYP2A6 (OR: 0.59; 95% CI: 0.40-0.86; P=0.00) or GSTP1 (OR: 0.62; 95% CI: 0.42-0.91; P=0.01) and who were regular tobacco users (cigarette smokers or tobacco chewers). Interestingly, only 27% of the cases carrying the variant forms of CYP2A6 (*1A/*4C+*1B/*4C+*4C/*4C) responded to the treatment for HNSCC when compared to those with wild-type genotype (69%). However with GSTP1, cases with homozygous mutant genotype (Val/Val) showed a superior treatment response (75%) when compared to cases with wild-type genotype (25%). Further, cases carrying a combination of variant genotype of CYP2A6 and wild-type genotype of GSTP1 exhibited a very poor treatment response demonstrating that polymorphisms in CYP2A6 and GSTP1 not only modified the risk to HNSCC but also played a major role in determining the chemotherapeutic response.
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Affiliation(s)
- Munindra Ruwali
- Developmental Toxicology Division, Indian Institute of Toxicology Research (CSIR), Lucknow, U.P., India
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Zhou SF, Liu JP, Chowbay B. Polymorphism of human cytochrome P450 enzymes and its clinical impact. Drug Metab Rev 2009; 41:89-295. [PMID: 19514967 DOI: 10.1080/03602530902843483] [Citation(s) in RCA: 498] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Pharmacogenetics is the study of how interindividual variations in the DNA sequence of specific genes affect drug response. This article highlights current pharmacogenetic knowledge on important human drug-metabolizing cytochrome P450s (CYPs) to understand the large interindividual variability in drug clearance and responses in clinical practice. The human CYP superfamily contains 57 functional genes and 58 pseudogenes, with members of the 1, 2, and 3 families playing an important role in the metabolism of therapeutic drugs, other xenobiotics, and some endogenous compounds. Polymorphisms in the CYP family may have had the most impact on the fate of therapeutic drugs. CYP2D6, 2C19, and 2C9 polymorphisms account for the most frequent variations in phase I metabolism of drugs, since almost 80% of drugs in use today are metabolized by these enzymes. Approximately 5-14% of Caucasians, 0-5% Africans, and 0-1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant enzyme that demonstrates multiple genetic variants with a potentially functional impact on the efficacy and adverse effects of drugs that are mainly eliminated by this enzyme. Studies into the CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and *3 alleles. Extensive polymorphism also occurs in other CYP genes, such as CYP1A1, 2A6, 2A13, 2C8, 3A4, and 3A5. Since several of these CYPs (e.g., CYP1A1 and 1A2) play a role in the bioactivation of many procarcinogens, polymorphisms of these enzymes may contribute to the variable susceptibility to carcinogenesis. The distribution of the common variant alleles of CYP genes varies among different ethnic populations. Pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and currently available drugs. Further studies are warranted to explore the gene-dose, gene-concentration, and gene-response relationships for these important drug-metabolizing CYPs.
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Affiliation(s)
- Shu-Feng Zhou
- School of Health Sciences, RMIT University, Bundoora, Victoria, Australia.
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37
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Koudsi NA, Ahluwalia JS, Lin SK, Sellers EM, Tyndale RF. A novel CYP2A6 allele (CYP2A6*35) resulting in an amino-acid substitution (Asn438Tyr) is associated with lower CYP2A6 activity in vivo. THE PHARMACOGENOMICS JOURNAL 2009; 9:274-82. [PMID: 19365400 PMCID: PMC2922203 DOI: 10.1038/tpj.2009.11] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Revised: 02/11/2009] [Accepted: 03/16/2009] [Indexed: 11/09/2022]
Abstract
Cytochrome P450 2A6 (CYP2A6) is the primary human enzyme involved in nicotine metabolism. The objective of this study was to characterize two nonsynonymous single nucleotide polymorphisms in CYP2A6(*)24, 594G>C (Val110Leu) and 6458A>T (Asn438Tyr). We determined their haplotype, allele frequencies, effect on CYP2A6 activity in vivo, as well as their stability and ability to metabolize nicotine in vitro. CYP2A6(*)35 (6458A>T) occurred at a frequency of 2.5-2.9% among individuals of black African descent, 0.5-0.8% among Asians and was not found in Caucasians. In addition, we identified two novel alleles, CYP2A6(*)36 (6458A>T and 6558T>C (Ile471Thr)) and CYP2A6(*)37 (6458A>T, 6558T>C and 6600G>T (Arg485Leu)). In vivo, CYP2A6(*)35 was associated with lower CYP2A6 activity as measured by the 3HC/COT ratio. In vitro, CYP2A6.35 had decreased nicotine C-oxidation activity and thermal stability. In conclusion, we identified three novel CYP2A6 alleles (CYP2A6(*)35, (*)36 and (*)37); the higher allele frequency variant CYP2A6(*)35 was associated with lower CYP2A6 activity.
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Affiliation(s)
- Nael Al Koudsi
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Jasjit S. Ahluwalia
- Department of Medicine and Masonic Cancer Centre, University of Minnesota, Minneapolis, MN
| | - Shih-Ku Lin
- Taipei City Hospital and Psychiatric Centre, Taipei, Taiwan
| | - Edward M. Sellers
- Clinical Pharmacology, Kendle Early Phase, Toronto, Ontario, Canada
- Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Rachel F. Tyndale
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
- Centre for Addiction and Mental Health, Toronto, Ontario, Canada
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Swan GE, Lessov-Schlaggar CN, Bergen AW, He Y, Tyndale RF, Benowitz NL. Genetic and environmental influences on the ratio of 3'hydroxycotinine to cotinine in plasma and urine. Pharmacogenet Genomics 2009; 19:388-98. [PMID: 19300303 PMCID: PMC2849278 DOI: 10.1097/fpc.0b013e32832a404f] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES The ratio of trans-3'hydroxycotinine/cotinine (3HC/COT) is a marker of CYP2A6 activity, an important determinant of nicotine metabolism. This analysis sought to conduct a combined genetic epidemiologic and pharmacogenetic investigation of the 3HC/COT ratio in plasma and urine. METHODS One hundred and thirty-nine twin pairs [110 monozygotic and 29 dizygotic] underwent a 30-min infusion of stable isotope-labelled nicotine and its major metabolite, cotinine, followed by an 8-h in-hospital stay. Blood and urine samples were taken at regular intervals for analysis of nicotine, cotinine, and metabolites. DNA was genotyped to confirm zygosity and for variation in the gene for the primary nicotine metabolic enzyme, CYP2A6 (variants genotyped: *1B, *1 x 2, *2, *4, *9, *12). Univariate biometric analyses quantified genetic and environmental influences on each measure in the presence and absence of covariates, including measured CYP2A6 genotype. RESULTS There was a substantial amount of variation in the free 3HC/COT ratio in plasma (6 h postinfusion) attributable to additive genetic influences (67.4%, 95% confidence interval=55.9-76.2%). The heritability estimate was reduced to 61.0 and 49.4%, respectively, after taking into account the effect of covariates and CYP2A6 genotype. In urine (collected over 8 h), the estimated amount of variation in the 3HC/COT ratio attributable to additive genetic influences was smaller (47.2%, 95% confidence interval=0-67.2%) and decreased to 44.6 and 42.0% after accounting for covariates and genotype. CONCLUSION Additive genetic factors are prominent in determining variation in plasma 3HC/COT but less so in determining variation in urine 3HC/COT.
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Affiliation(s)
- Gary E Swan
- Center for Health Sciences, SRI International, Menlo Park, CA 94025, USA.
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39
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Abstract
The molecular genetics of nicotine metabolism involves multiple polymorphic catalytic enzymes. Variation in metabolic pathways results in nicotine disposition kinetics that differ between individuals and ethnic groups. Twin studies indicate that a large part of this variance is genetic in origin, although environmental influences also contribute. The primary aim of this chapter is to review the current knowledge regarding the genetic variability in the enzymes that metabolize nicotine in humans. The focus is on describing the genetic polymorphisms that exist in cytochromes P450 (CYPs), aldehyde oxidase 1 (AOX1), UDP-glucuronosyltransferases (UGTs), and flavin-containing monooxygenase 3 (FMO3). Genetic studies have demonstrated that polymorphisms in CYP2A6, the primary enzyme responsible for nicotine breakdown, make a sizable contribution to the wide range of nicotine metabolic capacity observed in humans. Thus, special attention will be given to CYP2A6, because slower nicotine metabolism requires less frequent self-administration, and accordingly influences smoking behaviors. In addition, the molecular genetics of nicotine metabolism in nonhuman primates, mice, and rats will be reviewed briefly.
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Affiliation(s)
- Jill C Mwenifumbo
- Centre for Addiction & Mental Health and Department of Pharmacology, University of Toronto, Toronto, ON, Canada
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Association of nicotine metabolite ratio and CYP2A6 genotype with smoking cessation treatment in African-American light smokers. Clin Pharmacol Ther 2009; 85:635-43. [PMID: 19279561 DOI: 10.1038/clpt.2009.19] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cytochrome P450 2A6 (CYP2A6) is the main nicotine (NIC)-metabolizing enzyme in humans. We investigated the relationships between CYP2A6 genotype, baseline plasma trans- 3'-hydroxycotinine/cotinine (3HC/COT) (a phenotypic marker of CYP2A6 activity), and smoking behavior in African-American light smokers. Cigarette consumption, age of initiation, and dependence scores did not differ among 3HC/COT quartiles or CYP2A6 genotype groups. Slow metabolizers (SMs; both genetic and phenotypic) had significantly higher plasma NIC levels, suggesting that cigarette consumption was not reduced to adjust for slower rates of NIC metabolism. Individuals in the slowest 3HC/COT quartile had higher quitting rates with both placebo and NIC gum treatments (odds ratio 1.85, 95% confidence interval (CI) 1.08-3.16, P = 0.03). Similarly, the slowest CYP2A6 genotype group had higher quitting rates, although this trend did not reach significance (odds ratio 1.61, 95% CI 0.95-2.72, P = 0.08). The determination of the 3HC/COT ratio, and possibly CYP2A6 genotype, may be useful in the future for personalizing the choice of smoking cessation treatment in African-American light smokers.
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Ray R, Tyndale RF, Lerman C. Nicotine dependence pharmacogenetics: role of genetic variation in nicotine-metabolizing enzymes. J Neurogenet 2009; 23:252-61. [PMID: 19169923 PMCID: PMC3772540 DOI: 10.1080/01677060802572887] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Nicotine-dependence pharmacogenetics research is an emerging field, and a number of studies have begun to characterize the clinical relevance and predictive power of genetic variation in drug-metabolizing enzymes and drug target genes for response to medication. The present paper focuses on evidence for the role of nicotine-metabolizing enzymes in smoking behavior and response to treatment. Nicotine metabolism is mediated primarily by cytochrome P450 2A6 (CYP2A6). Genetic variation in the CYP2A6 gene has been linked with several smoking behavior phenotypes. Individuals who carry null or reduced activity alleles for CYP2A6 smoke fewer cigarettes per day, are less dependent on nicotine, and may have an easier time quitting smoking. A phenotypic measure of CYP2A6 enzyme activity, defined as the ratio of the nicotine metabolites 3'hydroxycotinine/cotinine, also predicts successful quitting with the transdermal nicotine patch, and counseling alone. Faster metabolizers of nicotine respond more poorly to these treatments; however, they may be excellent candidates for non-nicotine therapies, such as bupropion. Inherited variation in the CYP2B6 enzyme is also associated with response to bupropion treatment and counseling alone for smoking cessation. Inhibition of the CYP2A6 enzyme to slow nicotine metabolism is a promising approach to increase nicotine availability and potentially reduce harm from tobacco smoking.
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Affiliation(s)
- Riju Ray
- Abramson Cancer Center and Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Rachel F. Tyndale
- Centre for Addiction and Mental Health and Department of Pharmacology, Toronto, Ontario, Canada
| | - Caryn Lerman
- Abramson Cancer Center and Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Swan GE, Lessov-Schlaggar CN. Tobacco addiction and pharmacogenetics of nicotine metabolism. J Neurogenet 2009; 23:262-71. [PMID: 19152209 DOI: 10.1080/01677060802572903] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
This paper presents a brief overview of several components of tobacco addiction, including: 1) the epidemiology of smoking in the United States and elsewhere around the world; 2) implications of the pharmacogenetic study of nicotine metabolism for understanding tobacco addiction and its treatment; 3) the use of the twin design as an example of one strategy to understand the contribution of genetic and environmental factors to the pharmacokinetics of nicotine metabolism; 4) results from recent genomic studies of tobacco addiction in adults; and 5) a discussion of progress (past and future) toward the development of a comprehensive understanding of the pharmacogenetics of tobacco addiction and its treatment.
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Affiliation(s)
- Gary E Swan
- Center for Health Sciences, SRI International, Menlo Park, California 94025, USA.
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Rossini A, de Almeida Simão T, Albano RM, Pinto LFR. CYP2A6 polymorphisms and risk for tobacco-related cancers. Pharmacogenomics 2008; 9:1737-52. [PMID: 19018727 DOI: 10.2217/14622416.9.11.1737] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Tobacco consumption is the main identifiable risk to cancer, contributing to the majority of tumors in upper aerodigestive tissues. The psychoactive compound responsible for tobacco addiction, nicotine and the potent carcinogens present at high concentrations either in cigarette mainstream smoke or in smokeless tobacco products, 4-(methylnitrosamino)-1-(3-pyridyl)-butanone (NNK) and N-nitrosonornicotine (NNN) can be metabolized by CYP2A6. CYP2A6 is expressed in many aerodigestive tissues with high interindividual variability. The CYP2A6 gene is highly polymorphic and CYP2A6 alleles coding for enzymes with altered expression or metabolic capacity produce alterations in nicotine metabolism in vivo and seem to influence smoking behavior. These polymorphisms may change the rate of NNK and NNN activation and, therefore, may influence cancer risk associated with tobacco consumption. However, to date only a few and inconclusive studies have addressed the risk that a given CYP2A6 polymorphism presents for the development of tobacco-related tumors. Most, but not all, show a reduced risk associated with alleles that result in decreased enzyme activity. The overlapping substrate specificity and tissue expression between CYP2A6 and the highly similar CYP2A13 may add to the conflicting results observed. The intricate regulation of CYP2A6 and the variation of structurally different chemical compounds capable of inhibiting CYP2A enzymes also add to the complexity. Finally, the interaction between polymorphisms of genes that code for CYP2A6, CYP2A13 and other potent carcinogen-metabolizing CYP enzymes may help to determine individuals that are at higher risk of developing tumors associated with tobacco consumption.
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Affiliation(s)
- Ana Rossini
- Universidade do Estado do Rio de Janeiro, Instituto de Biologia Roberto Alcântara Gomes, Departamento de Bioquímica Brazil, Rio de Janeiro, Brazil
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Mwenifumbo JC, Al Koudsi N, Ho MK, Zhou Q, Hoffmann EB, Sellers EM, Tyndale RF. Novel and established CYP2A6 alleles impair in vivo nicotine metabolism in a population of Black African descent. Hum Mutat 2008; 29:679-88. [PMID: 18360915 DOI: 10.1002/humu.20698] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Cytochrome P450 2A6 (CYP2A6) is a human enzyme best known for metabolizing tobacco-related compounds, such as nicotine, cotinine (COT), and nitrosamine procarcinogens. CYP2A6 genetic variants have been associated with smoking status, cigarette consumption, and tobacco-related cancers. Our objective was to functionally characterize four nonsynonymous CYP2A6 sequence variants with respect to their haplotype, allele frequency, and association with in vivo CYP2A6 activity. In vivo, nicotine was administered orally to 281 volunteers of Black African descent. Blood samples were collected for kinetic phenotyping and CYP2A6 genotyping. In vitro, nicotine C-oxidation catalytic efficiencies of heterologously expressed variant enzymes were assessed. The four uncharacterized sequence variants were found in seven novel alleles CYP2A6(*)24A&B ; (*)25, (*)26, (*)27, and *28A&B, most were associated with impaired in vivo CYP2A6 activity. Nicotine metabolism groupings, based on the in vivo data of variant alleles, were created. Mean trans-3'-hydroxycotinine/cotinine (3HC/COT) differed (P<0.001) between normal (100%), intermediate (64%), and slow (40%) groups. Systemic exposure to nicotine following oral administration also differed (P<0.001) between normal (100%), intermediate (139%), and slow (162%) metabolism groups. In addition, alleles of individuals with unusual phenotype-genotype relationships were sequenced, resulting in the discovery of five novel uncharacterized alleles and at least one novel duplication allele. A total of 7% of this population of Black African descent had at least one of the eight novel characterized alleles and 29% had at least one previously established allele. These findings are important for increasing the accuracy of association studies between CYP2A6 genotype and behavioral, disease, or pharmacological phenotypes.
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Affiliation(s)
- Jill C Mwenifumbo
- Department of Pharmacology, University of Toronto, Toronto, Ontario, Canada
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