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Johnstone S, Cooper RK, Wray JM, Tonkin SS, Knapp KS, Colder CR, Maguin E, Mahoney MC, Tiffany ST, Brandon TH, Ashare RL, Tyndale RF, Hawk LW. Evaluating mediators of the effect of varenicline preloading on smoking abstinence in a randomized controlled trial. Addiction 2025; 120:1223-1237. [PMID: 39915904 DOI: 10.1111/add.16772] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 12/16/2024] [Indexed: 05/03/2025]
Abstract
BACKGROUND AND AIMS Mechanisms of varenicline preloading in promoting smoking abstinence have not been evaluated. Based on an extinction of reinforcement framework, we tested the hypothesis that pre-quit reductions in smoking rate mediate the effect of extended preloading on abstinence. We also tested alternative indicators of change in smoking reinforcement, as well as smoking aversion, nausea and abstinence self-efficacy as candidate mediators. DESIGN, PARTICIPANTS AND INTERVENTION Randomized, double-blind, placebo-controlled trial (NCT03262662) comparing extended (4-week varenicline) to standard (3 weeks of placebo, 1-week varenicline) preloading, preceding 11 weeks of open-label varenicline, in 320 adults (56% female). The primary outcome was self-reported continuous smoking abstinence during the last 4 weeks of treatment, with cotinine bio-verification at end of treatment (EOT). SETTING University at Buffalo, State University of New York, USA (part of the trial was conducted at participants' homes due to the COVID-19 pandemic). MEASUREMENTS Candidate mediators, including smoking rate and subjective effects of smoking (reward, satisfaction, aversion), self-reported craving, withdrawal, nausea and abstinence self-efficacy, were assessed daily during the pre-quit period with ecological momentary assessment. At two laboratory visits participants completed a choice task to assess smoking reinforcement. FINDINGS There was a statistically significant indirect effect of extended preloading on greater EOT abstinence rates through pre-quit declines in smoking rate [a*b = 0.284, 95% confidence interval (0.072,0.616)] and percent reduction in smoking across the pre-quit period [a*b = 0.225, (0.080,0.437)]. There were also statistically significant indirect effects through reductions in pre-quit craving [a*b = 0.150, (0.01,0.420)] and increases in pre-quit self-efficacy [a*b = 0.157, (0.038,0.375)]. Sex-specific analyses suggested these mediated effects were consistently limited to females. No other candidate mediators yielded statistically significant indirect effects. CONCLUSIONS Extended varenicline preloading mediated smoking abstinence through reduced pre-quit smoking and craving among female smokers seeking to quit; increased pre-quit abstinence self-efficacy was also a significant mediator.
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Affiliation(s)
| | - Robert K Cooper
- Department of Psychology, University at Buffalo, Buffalo, NY, USA
| | - Jennifer M Wray
- Ralph H Johnson Veteran's Affairs Healthcare System, Charleston, SC, USA
| | - Sarah S Tonkin
- Department of Psychology, University at Buffalo, Buffalo, NY, USA
- Health Promotion Research Center, University of Oklahoma health Sciences Center, Oklahoma City, OK, USA
| | - Kyler S Knapp
- School of Social Work, University at Buffalo, Buffalo, NY, USA
| | - Craig R Colder
- Department of Psychology, University at Buffalo, Buffalo, NY, USA
| | - Eugene Maguin
- Department of Psychology, University at Buffalo, Buffalo, NY, USA
| | - Martin C Mahoney
- Departments of Internal Medicine and Health Behavior, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | | | - Thomas H Brandon
- Department of Health Outcomes and Behavior, Moffitt Cancer Center, Tampa, FL, USA
| | - Rebecca L Ashare
- Department of Psychology, University at Buffalo, Buffalo, NY, USA
| | - Rachel F Tyndale
- Departments of Pharmacology and Toxicology, and Psychiatry, University of Toronto, Toronto, Canada
- Campbell Family Mental Health Research Institute, CAMH, Toronto, Canada
| | - Larry W Hawk
- Department of Psychology, University at Buffalo, Buffalo, NY, USA
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Young M, McLeod DSA, Richard K. Nicotine increases hepatocyte transthyretin turnover: A possible mechanism for the protective effect of smoking on preeclampsia? Mol Cell Endocrinol 2025; 597:112446. [PMID: 39725350 DOI: 10.1016/j.mce.2024.112446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2024] [Revised: 12/16/2024] [Accepted: 12/22/2024] [Indexed: 12/28/2024]
Abstract
Transthyretin is a thyroid hormone binding protein with a major role in the distribution of thyroid hormones to peripheral tissues. In preeclampsia, the failing placenta releases soluble endoglin into the maternal circulation causing systemic vascular dysfunction. Our group has previously shown that transthyretin binds to soluble endoglin and is taken up as a complex into hepatocytes. The risk of developing preeclampsia is greatly reduced by smoking cigarettes. The addictive component of cigarette smoke, nicotine, increases transthyretin expression in rodent brain and also stabilises binding between thyroxine and transthyretin. The aim of this study was to determine the effects of nicotine on transthyretin expression, secretion and uptake by hepatocytes and if nicotine altered the uptake of transthyretin bound soluble endoglin. Nicotine treatment increased transthyretin mRNA and protein levels in cultured hepatocytes. Using live cell imaging, Alexa-transthyretin uptake was significantly increased in the presence of nicotine. Alexa-soluble endoglin uptake was also significantly increased by exposure to nicotine. The transthyretin-Alexa-soluble endoglin complex was taken up via the low-density lipoprotein receptor related protein-1 (LRP1). LRP1 protein levels were unaffected in nicotine treated hepatocytes. Nicotine exposure increases hepatocyte synthesis, secretion and uptake of transthyretin as well as cell uptake of soluble endoglin. Nicotine may protect against preeclampsia by increasing serum TTR which can bind soluble endoglin and remove it from the circulation. Further research is required to better understand the role of transthyretin and nicotine in mitigating preeclampsia.
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Affiliation(s)
- Melanie Young
- Conjoint Endocrine Laboratory, Chemical Pathology, Pathology Queensland, Queensland Health, Herston, Qld 4029, Australia
| | - Donald S A McLeod
- Department of Endocrinology and Diabetes, Royal Brisbane and Women's Hospital, Herston, Qld 4029, Australia
| | - Kerry Richard
- Conjoint Endocrine Laboratory, Chemical Pathology, Pathology Queensland, Queensland Health, Herston, Qld 4029, Australia; School of Medicine, University of Queensland, Herston, Qld 4029, Australia; School of Biomedical Sciences, Queensland University of Technology, Brisbane, Qld 4000, Australia.
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Langlois AW, Chenoweth MJ, Twesigomwe D, Scantamburlo G, Whirl-Carrillo M, Sangkuhl K, Klein TE, Nofziger C, Tyndale RF, Gaedigk A. PharmVar GeneFocus: CYP2A6. Clin Pharmacol Ther 2024; 116:948-962. [PMID: 39051767 PMCID: PMC11452280 DOI: 10.1002/cpt.3387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Accepted: 07/08/2024] [Indexed: 07/27/2024]
Abstract
The Pharmacogene Variation Consortium (PharmVar) provides nomenclature for the human CYP2A gene locus containing the highly polymorphic CYP2A6 gene. CYP2A6 plays a role in the metabolism of nicotine and various drugs. Thus, genetic variation can substantially contribute to the function of this enzyme and associated efficacy and safety. This GeneFocus provides an overview of the clinical significance of CYP2A6, including its genetic variation and function. We also highlight and discuss caveats in the identification and characterization of allelic variation of this complex pharmacogene, a prerequisite for accurate genotype determination and prediction of phenotype status.
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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
| | - 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
- Department of Psychiatry, University of Toronto; 250 College Street, Toronto, ON, M5T 1R8, Canada
| | - David Twesigomwe
- Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | | | | | - Katrin Sangkuhl
- Department of Biomedical Data Science, Stanford University, Stanford, California, USA
| | - Teri E. Klein
- Department of Biomedical Data Science, Stanford University, Stanford, California, USA
- Departments of Medicine (BMIR) and Genetics, Stanford University, Stanford, California, USA
| | | | - 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
| | - Andrea Gaedigk
- Division of Clinical Pharmacology, Toxicology and Therapeutic Innovation, Children’s Mercy Research Institute (CMRI), Kansas City, Missouri, USA and School of Medicine, University of Missouri-Kansas City, Kansas City, Missouri, USA
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Wang E, Andrade MJ, Smith Q. Vascularized liver-on-a-chip model to investigate nicotine-induced dysfunction. BIOMICROFLUIDICS 2023; 17:064108. [PMID: 38155919 PMCID: PMC10754629 DOI: 10.1063/5.0172677] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 11/29/2023] [Indexed: 12/30/2023]
Abstract
The development of physiologically relevant in vitro systems for simulating disease onset and progression and predicting drug metabolism holds tremendous value in reducing drug discovery time and cost. However, many of these platforms lack accuracy in replicating the tissue architecture and multicellular interactions. By leveraging three-dimensional cell culture, biomimetic soft hydrogels, and engineered stimuli, in vitro models have continued to progress. Nonetheless, the incorporation of the microvasculature has been met with many challenges, specifically with the addition of parenchymal cell types. Here, a systematic approach to investigating the initial seeding density of endothelial cells and its effects on interconnected networks was taken and combined with hepatic spheroids to form a liver-on-a-chip model. Leveraging this system, nicotine's effects on microvasculature and hepatic function were investigated. The findings indicated that nicotine led to interrupted adherens junctions, decreased guanosine triphosphate cyclohydrolase 1 expression, impaired angiogenesis, and lowered barrier function, all key factors in endothelial dysfunction. With the combination of the optimized microvascular networks, a vascularized liver-on-a-chip was formed, providing functional xenobiotic metabolism and synthesis of both albumin and urea. This system provides insight into potential hepatotoxicity caused by various drugs and allows for assessing vascular dysfunction in a high throughput manner.
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Affiliation(s)
- Eric Wang
- Department of Chemical and Biomolecular Engineering, University of California Irvine, Irvine, California 92697, USA
| | - Melisa J. Andrade
- Department of Chemical and Biomolecular Engineering, University of California Irvine, Irvine, California 92697, USA
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Bian J, Zhao J, Zhao Y, Hao X, He S, Li Y, Huang L. Impact of individual factors on DNA methylation of drug metabolism genes: A systematic review. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2023; 64:401-415. [PMID: 37522536 DOI: 10.1002/em.22567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 07/12/2023] [Accepted: 07/26/2023] [Indexed: 08/01/2023]
Abstract
Individual differences in drug response have always existed in clinical treatment. Many non-genetic factors show non-negligible impacts on personalized medicine. Emerging studies have demonstrated epigenetic could connect non-genetic factors and individual treatment differences. We used systematic retrieval methods and reviewed studies that showed individual factors' impact on DNA methylation of drug metabolism genes. In total, 68 studies were included, and half (n = 36) were cohort studies. Six aspects of individual factors were summarized from the perspective of personalized medicine: parental exposure, environmental pollutants exposure, obesity and diet, drugs, gender and others. The most research (n = 11) focused on ABCG1 methylation. The majority of studies showed non-genetic factors could result in a significant DNA methylation alteration in drug metabolism genes, which subsequently affects the pharmacokinetic processes. However, the underlying mechanism remained unknown. Finally, some viewpoints were presented for future research.
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Affiliation(s)
- Jialu Bian
- Department of Pharmacy, People's Hospital of Peking University, Beijing, China
- Department of Pharmacy Administration and Clinical Pharmacy, School of Pharmaceutical Science, Peking University, Beijing, China
| | - Jinxia Zhao
- Department of Pharmacy, People's Hospital of Peking University, Beijing, China
- Department of Pharmacy Administration and Clinical Pharmacy, School of Pharmaceutical Science, Peking University, Beijing, China
| | - Yinyu Zhao
- Department of Pharmacy, People's Hospital of Peking University, Beijing, China
- Department of Pharmacy Administration and Clinical Pharmacy, School of Pharmaceutical Science, Peking University, Beijing, China
| | - Xu Hao
- Department of Pharmacy, People's Hospital of Peking University, Beijing, China
| | - Shiyu He
- Department of Pharmacy, People's Hospital of Peking University, Beijing, China
- Department of Pharmacy Administration and Clinical Pharmacy, School of Pharmaceutical Science, Peking University, Beijing, China
| | - Yuanyuan Li
- Department of Pharmacy, People's Hospital of Peking University, Beijing, China
| | - Lin Huang
- Department of Pharmacy, People's Hospital of Peking University, Beijing, China
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Yadav A, Kesharwani A, Chaurasia DK, Katara P. Mining of molecular insights of CYP2A6 and its variants complex with coumarin (CYP2A6*-coumarin) using molecular dynamics simulation. J Biomol Struct Dyn 2023; 41:4081-4092. [PMID: 35427216 DOI: 10.1080/07391102.2022.2062785] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 04/02/2022] [Indexed: 10/18/2022]
Abstract
CYP2A6 is a very important enzyme that plays a crucial role in nicotine compounds and is responsible for the metabolism of more than 3% drugs of total metabolized drugs by the CYP family and reported as one of very important pharmacogenes. CYP2A6 is highly polymorphic in nature and reported with more than 40 variants, most of these variants are SNPs originated and population specific. It has been well observed and reported that the presence of these population-specific non-synonymous SNPs in CYP2A6 alters the rate of drug metabolism and as a functional consequence, drugs produce an abnormal response. Though genomics and pharmacogenomics studies are there, very less is known about the structural effects of these SNPs on molecular-interaction and folding of CYP2A6. To fill the knowledge gap, SNPs based four variants, i.e., CYP2A6*2, CYP2A6*18, CYP2A6*21, and CYP2A6*35, which are frequently reported in the South Asian population, were considered for the study. Coumarin (DB04665), a well reported drug, is considered as a model substance, and the effect of all four variants on 'CYP2A6*-coumarin' complex was studied. MD simulation-based analysis (at 200 ns) was performed and comparative analysis with respect to wild type 'CYP2A6-coumarin' complex was done. Though observation didn't find any global effect on complete complex but found some crucial minor-local alteration in interaction and folding process. It is assumed that the change due to SNPs in the single amino acid did not bring global change in physiochemical properties of CYP2A6* but caused local-trivial changes which are very crucial for its metabolic activity.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Anamika Yadav
- Computational omics Lab, Centre of Bioinformatics, University of Allahabad, Prayagraj, India
| | - Akanksha Kesharwani
- Computational omics Lab, Centre of Bioinformatics, University of Allahabad, Prayagraj, India
- Supercomputing Facility for Bioinformatics and Computational Biology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
| | - Dheeraj Kumar Chaurasia
- Supercomputing Facility for Bioinformatics and Computational Biology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
| | - Pramod Katara
- Computational omics Lab, Centre of Bioinformatics, University of Allahabad, Prayagraj, India
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Oh S, Kim S, Sung E, Kim CH, Kang JH, Shin H, Cho IY. The association between cotinine-measured smoking
intensity and sleep quality. Tob Induc Dis 2022; 20:77. [PMID: 36118556 PMCID: PMC9443078 DOI: 10.18332/tid/152221] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/29/2022] [Accepted: 07/19/2022] [Indexed: 11/24/2022] Open
Abstract
INTRODUCTION METHODS RESULTS CONCLUSIONS
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Affiliation(s)
- Supa Oh
- Department of Family Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Sinae Kim
- Division of Biostatistics, Department of R&D Management, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Eunju Sung
- Department of Family Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Cheol-Hwan Kim
- Department of Family Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Jae-Heon Kang
- Department of Family Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Hocheol Shin
- Department of Family Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - In Young Cho
- Department of Family Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
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Emoto C, Johnson TN. Cytochrome P450 enzymes in the pediatric population: Connecting knowledge on P450 expression with pediatric pharmacokinetics. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2022; 95:365-391. [PMID: 35953161 DOI: 10.1016/bs.apha.2022.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Cytochrome P450 enzymes play an important role in the pharmacokinetics, efficacy, and toxicity of drugs. Age-dependent changes in P450 enzyme expression have been studied based on several detection systems, as well as by deconvolution of in vivo pharmacokinetic data observed in pediatric populations. The age-dependent changes in P450 enzyme expression can be important determinants of drug disposition in childhood, in addition to the changes in body size and the other physiological parameters, and effects of pharmacogenetics and disease on organ functions. As a tool incorporating drug-specific and body-specific factors, physiologically-based pharmacokinetic (PBPK) models have become increasingly used to characterize and explore mechanistic insights into drug disposition. Thus, PBPK models can be a bridge between findings from basic science and utilization in predictive science. Pediatric PBPK models incorporate additional system specific information on developmental physiology and ontogeny and have been used to predict pharmacokinetic parameters from preterm neonates onwards. These models have been advocated by regulatory authorities in order to support pediatric clinical trials. The purpose of this chapter is to highlight accumulated knowledge and findings from basic research focusing on P450 enzymes, as well as the current status and future challenges of expanding the utilization of pediatric PBPK modeling.
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Affiliation(s)
- Chie Emoto
- Laboratory of Drug Metabolism and Pharmacokinetics, Showa Pharmaceutical University, Tokyo, Japan; Translational Research Division, Chugai Pharmaceutical Co., Ltd., Tokyo, Japan.
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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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Archie SR, Sharma S, Burks E, Abbruscato T. Biological determinants impact the neurovascular toxicity of nicotine and tobacco smoke: A pharmacokinetic and pharmacodynamics perspective. Neurotoxicology 2022; 89:140-160. [PMID: 35150755 PMCID: PMC8958572 DOI: 10.1016/j.neuro.2022.02.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 01/30/2022] [Accepted: 02/05/2022] [Indexed: 01/01/2023]
Abstract
Accumulating evidence suggests that the detrimental effect of nicotine and tobacco smoke on the central nervous system (CNS) is caused by the neurotoxic role of nicotine on blood-brain barrier (BBB) permeability, nicotinic acetylcholine receptor expression, and the dopaminergic system. The ultimate consequence of these nicotine associated neurotoxicities can lead to cerebrovascular dysfunction, altered behavioral outcomes (hyperactivity and cognitive dysfunction) as well as future drug abuse and addiction. The severity of these detrimental effects can be associated with several biological determinants. Sex and age are two important biological determinants which can affect the pharmacokinetics and pharmacodynamics of several systemically available substances, including nicotine. With regard to sex, the availability of gonadal hormone is impacted by the pregnancy status and menstrual cycle resulting in altered metabolism rate of nicotine. Additionally, the observed lower smoking cessation rate in females compared to males is a consequence of differential effects of sex on pharmacokinetics and pharmacodynamics of nicotine. Similarly, age-dependent alterations in the pharmacokinetics and pharmacodynamics of nicotine have also been observed. One such example is related to severe vulnerability of adolescence towards addiction and long-term behavioral changes which may continue through adulthood. Considering the possible neurotoxic effects of nicotine on the central nervous system and the deterministic role of sex as well as age on these neurotoxic effects of smoking, it has become important to consider sex and age to study nicotine induced neurotoxicity and development of treatment strategies for combating possible harmful effects of nicotine. In the future, understanding the role of sex and age on the neurotoxic actions of nicotine can facilitate the individualization and optimization of treatment(s) to mitigate nicotine induced neurotoxicity as well as smoking cessation therapy. Unfortunately, however, no such comprehensive study is available which has considered both the sex- and age-dependent neurotoxicity of nicotine, as of today. Hence, the overreaching goal of this review article is to analyze and summarize the impact of sex and age on pharmacokinetics and pharmacodynamics of nicotine and possible neurotoxic consequences associated with nicotine in order to emphasize the importance of including these biological factors for such studies.
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Affiliation(s)
- Sabrina Rahman Archie
- Department of Pharmaceutical Sciences, Jerry H. Hodge School of Pharmacy, Texas Tech University Health Sciences Center (TTUHSC), Amarillo, TX, USA
| | - Sejal Sharma
- Department of Pharmaceutical Sciences, Jerry H. Hodge School of Pharmacy, Texas Tech University Health Sciences Center (TTUHSC), Amarillo, TX, USA
| | - Elizabeth Burks
- Department of Pharmaceutical Sciences, Jerry H. Hodge School of Pharmacy, Texas Tech University Health Sciences Center (TTUHSC), Amarillo, TX, USA
| | - Thomas Abbruscato
- Department of Pharmaceutical Sciences, Jerry H. Hodge School of Pharmacy, Texas Tech University Health Sciences Center (TTUHSC), Amarillo, TX, USA.
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Abstract
Almost 50% of prescription drugs lack age-appropriate dosing guidelines and therefore are used "off-label." Only ~10% drugs prescribed to neonates and infants have been studied for safety or efficacy. Immaturity of drug metabolism in children is often associated with drug toxicity. This chapter summarizes data on the ontogeny of major human metabolizing enzymes involved in oxidation, reduction, hydrolysis, and conjugation of drugs. The ontogeny data of individual drug-metabolizing enzymes are important for accurate prediction of drug pharmacokinetics and toxicity in children. This information is critical for designing clinical studies to appropriately test pharmacological hypotheses and develop safer pediatric drugs, and to replace the long-standing practice of body weight- or surface area-normalized drug dosing. The application of ontogeny data in physiologically based pharmacokinetic model and regulatory submission are discussed.
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Lim SYM, Alshagga MA, Alshawsh MA, Ong CE, Pan Y. In vitro effects of 95% khat ethanol extract (KEE) on human recombinant cytochrome P450 (CYP)1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2 and CYP3A5. Drug Metab Pers Ther 2021; 37:55-67. [PMID: 35146975 DOI: 10.1515/dmpt-2021-1000196] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 06/21/2021] [Indexed: 12/17/2022]
Abstract
OBJECTIVES Khat, a natural amphetamine-like psychostimulant plant, are widely consumed globally. Concurrent intake of khat and xenobiotics may lead to herb-drug interactions and adverse drug reactions (ADRs). This study is a continuation of our previous study, targeted to evaluate the in vitro inhibitory effects of khat ethanol extract (KEE) on human cytochrome (CYP) 1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2, and CYP3A5, major human drug metabolizing enzymes. METHODS In vitro fluorescence enzyme assays were employed to assess CYPs inhibition with the presence and absence of various KEE concentrations. RESULTS KEE reversibly inhibited CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2 and CYP3A5 but not CYP1A2 with IC50 values of 25.5, 99, 4.5, 21, 27, 17, and 10 μg/mL respectively. No irreversible inhibition of KEE on all the eight CYPs were identified. The Ki values of CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2 and CYP3A5 were 20.9, 85, 4.8, 18.3, 59.3, 3, and 21.7 μg/mL, respectively. KEE inhibited CYP2B6 via competitive or mixed inhibition; CYP2E1 via un-competitive or mixed inhibition; while CYP2A6, CYP2C8, CYP2C19, CYP2J2 and CYP3A5 via non-competitive or mixed inhibition. CONCLUSIONS Caution should be taken by khat users who are on medications metabolized by CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2, and CYP3A5.
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Affiliation(s)
- Sharoen Yu Ming Lim
- Division of Biomedical Science, School of Pharmacy, University of Nottingham Malaysia Campus, Semenyih, Selangor Darul Ehsan, Malaysia
| | - Mustafa Ahmed Alshagga
- Division of Biomedical Science, School of Pharmacy, University of Nottingham Malaysia Campus, Semenyih, Selangor Darul Ehsan, Malaysia
| | | | - Chin Eng Ong
- School of Pharmacy, International Medical University, Wilayah Persekutuan, Kuala Lumpur, Malaysia
| | - Yan Pan
- Division of Biomedical Science, School of Pharmacy, University of Nottingham Malaysia Campus, Semenyih, Selangor Darul Ehsan, Malaysia
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Pérez-Rubio G, López-Flores LA, Cupertino AP, Cartujano-Barrera F, Reynales-Shigematsu LM, Ramírez M, Ellerbeck EF, Rodríguez-Bolaños R, Falfan-Valencia R. Genetic Variants in Smoking-Related Genes in Two Smoking Cessation Programs: A Cross-Sectional Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18126597. [PMID: 34205269 PMCID: PMC8296383 DOI: 10.3390/ijerph18126597] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 06/08/2021] [Accepted: 06/16/2021] [Indexed: 12/15/2022]
Abstract
Previous studies have identified variants in genes encoding proteins associated with the degree of addiction, smoking onset, and cessation. We aimed to describe thirty-one single nucleotide polymorphisms (SNPs) in seven candidate genomic regions spanning six genes associated with tobacco-smoking in a cross-sectional study from two different interventions for quitting smoking: (1) thirty-eight smokers were recruited via multimedia to participate in e-Decídete! program (e-Dec) and (2) ninety-four attended an institutional smoking cessation program on-site. SNPs genotyping was done by real-time PCR using TaqMan probes. The analysis of alleles and genotypes was carried out using the EpiInfo v7. on-site subjects had more years smoking and tobacco index than e-Dec smokers (p < 0.05, both); in CYP2A6 we found differences in the rs28399433 (p < 0.01), the e-Dec group had a higher frequency of TT genotype (0.78 vs. 0.35), and TG genotype frequency was higher in the on-site group (0.63 vs. 0.18), same as GG genotype (0.03 vs. 0.02). Moreover, three SNPs in NRXN1, two in CHRNA3, and two in CHRNA5 had differences in genotype frequencies (p < 0.01). Cigarettes per day were different (p < 0.05) in the metabolizer classification by CYP2A6 alleles. In conclusion, subjects attending a mobile smoking cessation intervention smoked fewer cigarettes per day, by fewer years, and by fewer cumulative pack-years. There were differences in the genotype frequencies of SNPs in genes related to nicotine metabolism and nicotine dependence. Slow metabolizers smoked more cigarettes per day than intermediate and normal metabolizers.
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Affiliation(s)
- Gloria Pérez-Rubio
- HLA Laboratory, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Calzada de Tlalpan 4502, Sección XVI, Mexico City 14080, Mexico; (G.P.-R.); (L.A.L.-F.)
| | - Luis Alberto López-Flores
- HLA Laboratory, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Calzada de Tlalpan 4502, Sección XVI, Mexico City 14080, Mexico; (G.P.-R.); (L.A.L.-F.)
| | - Ana Paula Cupertino
- Department of Cancer Prevention and Control, Hackensack University Medical Center, Hackensack, NJ 07601, USA; (A.P.C.); (F.C.-B.)
| | - Francisco Cartujano-Barrera
- Department of Cancer Prevention and Control, Hackensack University Medical Center, Hackensack, NJ 07601, USA; (A.P.C.); (F.C.-B.)
| | | | - Mariana Ramírez
- Department of Preventive Medicine and Public Health, University of Kansas Medical Center, Kansas City, KS 66160, USA; (M.R.); (E.F.E.)
| | - Edward F. Ellerbeck
- Department of Preventive Medicine and Public Health, University of Kansas Medical Center, Kansas City, KS 66160, USA; (M.R.); (E.F.E.)
| | - Rosibel Rodríguez-Bolaños
- Department of Tobacco Research, Instituto Nacional de Salud Pública, Cuernavaca 62100, Mexico; (L.M.R.-S.); (R.R.-B.)
| | - Ramcés Falfan-Valencia
- HLA Laboratory, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Calzada de Tlalpan 4502, Sección XVI, Mexico City 14080, Mexico; (G.P.-R.); (L.A.L.-F.)
- Correspondence: ; Tel.: +52-55-5487-1700 (ext. 5152)
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Abstract
The regulation of brain cytochrome P450 enzymes (CYPs) is different compared with respective hepatic enzymes. This may result from anatomical bases and physiological functions of the two organs. The brain is composed of a variety of functional structures built of different interconnected cell types endowed with specific receptors that receive various neuronal signals from other brain regions. Those signals activate transcription factors or alter functioning of enzyme proteins. Moreover, the blood-brain barrier (BBB) does not allow free penetration of all substances from the periphery into the brain. Differences in neurotransmitter signaling, availability to endogenous and exogenous active substances, and levels of transcription factors between neuronal and hepatic cells lead to differentiated expression and susceptibility to the regulation of CYP genes in the brain and liver. Herein, we briefly describe the CYP enzymes of CYP1-3 families, their distribution in the brain, and discuss brain-specific regulation of CYP genes. In parallel, a comparison to liver CYP regulation is presented. CYP enzymes play an essential role in maintaining the levels of bioactive molecules within normal ranges. These enzymes modulate the metabolism of endogenous neurochemicals, such as neurosteroids, dopamine, serotonin, melatonin, anandamide, and exogenous substances, including psychotropics, drugs of abuse, neurotoxins, and carcinogens. The role of these enzymes is not restricted to xenobiotic-induced neurotoxicity, but they are also involved in brain physiology. Therefore, it is crucial to recognize the function and regulation of CYP enzymes in the brain to build a foundation for future medicine and neuroprotection and for personalized treatment of brain diseases.
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Affiliation(s)
- Wojciech Kuban
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Władysława Anna Daniel
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
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15
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Lkhagvadorj K, Zeng Z, Meyer KF, Verweij LP, Kooistra W, Reinders-Luinge M, Dijkhuizen HW, de Graaf IAM, Plösch T, Hylkema MN. Postnatal Smoke Exposure Further Increases the Hepatic Nicotine Metabolism in Prenatally Smoke Exposed Male Offspring and Is Linked with Aberrant Cyp2a5 Methylation. Int J Mol Sci 2020; 22:ijms22010164. [PMID: 33375250 PMCID: PMC7795156 DOI: 10.3390/ijms22010164] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/22/2020] [Accepted: 12/23/2020] [Indexed: 12/16/2022] Open
Abstract
Prenatal smoke exposure (PreSE) is a risk factor for nicotine dependence, which is further enhanced by postnatal smoke exposure (PostSE). One susceptibility gene to nicotine dependence is Cytochrome P450 (CYP) 2A6, an enzyme responsible for the conversion of nicotine to cotinine in the liver. Higher CYP2A6 activity is associated with nicotine dependence and could be regulated through DNA methylation. In this study we investigated whether PostSE further impaired PreSE-induced effects on nicotine metabolism, along with Cyp2a5, orthologue of CYP2A6, mRNA expression and DNA methylation. Using a mouse model where prenatally smoke-exposed adult offspring were exposed to cigarette smoke for 3 months, enzyme activity, mRNA levels, and promoter methylation of hepatic Cyp2a5 were evaluated. We found that in male offspring, PostSE increased PreSE-induced cotinine levels and Cyp2a5 mRNA expression. In addition, both PostSE and PreSE changed Cyp2a5 DNA methylation in male groups. PreSE however decreased cotinine levels whereas it had no effect on Cyp2a5 mRNA expression or methylation. These adverse outcomes of PreSE and PostSE were most prominent in males. When considered in the context of the human health aspects, the combined effect of prenatal and adolescent smoke exposure could lead to an accelerated risk for nicotine dependence later in life.
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Affiliation(s)
- Khosbayar Lkhagvadorj
- University Medical Center Groningen, Department of Pathology and Medical Biology, University of Groningen, 9713 GZ Groningen, The Netherlands; (K.L.); (Z.Z.); (K.F.M.); (L.P.V.); (W.K.); (M.R.-L.)
- GRIAC Research Institute, University of Groningen, 9713 AV Groningen, The Netherlands
- Department of Pulmonology and Allergology, Mongolian National University of Medical Sciences, Ulaanbaatar 14210, Mongolia
| | - Zhijun Zeng
- University Medical Center Groningen, Department of Pathology and Medical Biology, University of Groningen, 9713 GZ Groningen, The Netherlands; (K.L.); (Z.Z.); (K.F.M.); (L.P.V.); (W.K.); (M.R.-L.)
- GRIAC Research Institute, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Karolin F. Meyer
- University Medical Center Groningen, Department of Pathology and Medical Biology, University of Groningen, 9713 GZ Groningen, The Netherlands; (K.L.); (Z.Z.); (K.F.M.); (L.P.V.); (W.K.); (M.R.-L.)
- GRIAC Research Institute, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Laura P. Verweij
- University Medical Center Groningen, Department of Pathology and Medical Biology, University of Groningen, 9713 GZ Groningen, The Netherlands; (K.L.); (Z.Z.); (K.F.M.); (L.P.V.); (W.K.); (M.R.-L.)
- GRIAC Research Institute, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Wierd Kooistra
- University Medical Center Groningen, Department of Pathology and Medical Biology, University of Groningen, 9713 GZ Groningen, The Netherlands; (K.L.); (Z.Z.); (K.F.M.); (L.P.V.); (W.K.); (M.R.-L.)
- GRIAC Research Institute, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Marjan Reinders-Luinge
- University Medical Center Groningen, Department of Pathology and Medical Biology, University of Groningen, 9713 GZ Groningen, The Netherlands; (K.L.); (Z.Z.); (K.F.M.); (L.P.V.); (W.K.); (M.R.-L.)
- GRIAC Research Institute, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Henk W. Dijkhuizen
- Faculty of Science and Engineering, University of Groningen, 9713 GZ Groningen, The Netherlands;
| | - Inge A. M. de Graaf
- Department of Pharmacokinetics, Toxicology and Targeting, Groningen Research Institute of Pharmacy, University of Groningen, 9713 AV Groningen, The Netherlands;
| | - Torsten Plösch
- University Medical Center Groningen, Department of Obstetrics and Gynecology, University of Groningen, 9713 GZ Groningen, The Netherlands;
| | - Machteld N. Hylkema
- University Medical Center Groningen, Department of Pathology and Medical Biology, University of Groningen, 9713 GZ Groningen, The Netherlands; (K.L.); (Z.Z.); (K.F.M.); (L.P.V.); (W.K.); (M.R.-L.)
- GRIAC Research Institute, University of Groningen, 9713 AV Groningen, The Netherlands
- Correspondence:
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16
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Lkhagvadorj K, Meyer KF, Verweij LP, Kooistra W, Reinders-Luinge M, Dijkhuizen HW, de Graaf IAM, Plösch T, Hylkema MN. Prenatal smoke exposure induces persistent Cyp2a5 methylation and increases nicotine metabolism in the liver of neonatal and adult male offspring. Epigenetics 2020; 15:1370-1385. [PMID: 32573327 PMCID: PMC7678918 DOI: 10.1080/15592294.2020.1782655] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 05/12/2020] [Accepted: 05/15/2020] [Indexed: 02/08/2023] Open
Abstract
Prenatal smoke exposure (PSE) is a risk factor for nicotine dependence. One susceptibility gene for nicotine dependence is Cytochrome P450 (CYP) 2A6, an enzyme responsible for the conversion of nicotine to cotinine and nicotine clearance in the liver. Higher activity of the CYP2A6 enzyme is associated with nicotine dependence, but no research has addressed the PSE effects on the CYP2A6 gene or its mouse homologue Cyp2a5. We hypothesized that PSE affects Cyp2a5 promoter methylation, Cyp2a5 mRNA levels, and nicotine metabolism in offspring. We used a smoke-exposed pregnant mouse model. RNA, DNA, and microsomal protein were isolated from liver tissue of foetal, neonatal, and adult offspring. Enzyme activity, Cyp2a5 mRNA levels, and Cyp2a5 methylation status of six CpG sites within the promoter region were analysed via HPLC, RT-PCR, and bisulphite pyrosequencing. Our data show that PSE induced higher cotinine levels in livers of male neonatal and adult offspring compared to controls. PSE-induced cotinine levels in neonates correlated with Cyp2a5 mRNA expression and promoter methylation at CpG-7 and CpG+45. PSE increased methylation in almost all CpG sites in foetal offspring, and this effect persisted at CpG-74 in male neonatal and adult offspring. Our results indicate that male offspring of mothers which were exposed to cigarette smoke during pregnancy have a higher hepatic nicotine metabolism, which could be regulated by DNA methylation. Given the detected persistence into adulthood, extrapolation to the human situation suggests that sons born from smoking mothers could be more susceptible to nicotine dependence later in life.
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Affiliation(s)
- Khosbayar Lkhagvadorj
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Department of Pulmonology and Allergology, Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia
| | - Karolin F. Meyer
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Laura P. Verweij
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Wierd Kooistra
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Marjan Reinders-Luinge
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Henk W. Dijkhuizen
- Faculty of Science and Engineering, University of Groningen, Groningen, The Netherlands
| | - Inge A. M. de Graaf
- Department of Pharmacokinetics, Toxicology, and Targeting, Groningen Research Institute of Pharmacy, University of Groningen, Groningen, The Netherlands
| | - Torsten Plösch
- Department of Obstetrics and Gynecology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Machteld N. Hylkema
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- GRIAC Research Institute, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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17
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Gao Y, Miksys S, Palmour RM, Tyndale RF. The Influence of Tobacco Smoke/Nicotine on CYP2A Expression in Human and African Green Monkey Lungs. Mol Pharmacol 2020; 98:658-668. [PMID: 33055223 DOI: 10.1124/molpharm.120.000100] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 09/17/2020] [Indexed: 11/22/2022] Open
Abstract
CYP2A enzymes metabolically inactivate nicotine and activate tobacco-derived procarcinogens [e.g., 4-[methylnitrosamino]-1-(3-pyridyl)-1-butanone]. Smoking decreases nicotine clearance, and chronic nicotine reduces hepatic CYP2A activity. However, little is known about the impact of smoking or nicotine on the expression of CYP2A in the lung. We investigated 1) the levels of human lung CYP2A mRNA in smokers versus nonsmokers and 2) the impact of daily nicotine treatment on lung CYP2A protein levels in African green monkeys (AGMs). Lung CYP2A13, CYP2A6, and CYP2A7 (and CYP1A2) mRNA levels in smokers and nonsmokers were assessed in Gene Expression Omnibus data sets (GSE30063, GSE108134, and GSE11784). The impact of chronic, twice-daily, subcutaneous nicotine at two doses (0.3 and 0.5 mg/kg) versus vehicle on lung CYP2A protein levels was assessed. The impact of ethanol self-administration was also investigated, with and without nicotine treatment. Smokers versus nonsmokers (from GSE30063 and GSE108134) had lower (1.04- to 1.12-fold) levels of lung CYP2A13, CYP2A6, and CYP2A7 (and higher CYP1A2) mRNA. Both doses of nicotine tested decreased AGM lung CYP2A protein (3- to 7-fold). Ethanol self-administration had no effect on AGM lung CYP2A protein, and there was no interaction between ethanol and nicotine. Our results suggest that smoking was associated with a reduction in human lung CYP2A13, CYP2A6, and CYP2A7 mRNA, consistent with the role of nicotine treatment in reducing AGM lung CYP2A protein. This regulation by smoking/nicotine will increase interindividual variation in lung CYP2A levels, which may impact the localized metabolism of inhaled drugs and tobacco smoke procarcinogens. SIGNIFICANCE STATEMENT: CYP2A13 and CYP2A6 are expressed in the lung and may contribute to local procarcinogen activation. Smokers had lower lung CYP2A mRNA levels compared with nonsmokers. Lung CYP2A protein expression was decreased by systemic treatment with nicotine. Decreased lung CYP2A expression may alter smoking-related lung cancer risk and tissue damage from other inhaled toxins. This novel regulatory impact of nicotine, including nicotine found in smoking-cessation nicotine-replacement therapies, may have potential benefits on smoking-related lung cancer risk.
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Affiliation(s)
- Yuan Gao
- Department of Pharmacology and Toxicology, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH) (Y.G., S.M., R.F.T.) and Department of Psychiatry (R.F.T.), University of Toronto, Toronto, Ontario, Canada and Department of Psychiatry and Human Genetics, McGill University, Montreal, Quebec, Canada (R.M.P.)
| | - Sharon Miksys
- Department of Pharmacology and Toxicology, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH) (Y.G., S.M., R.F.T.) and Department of Psychiatry (R.F.T.), University of Toronto, Toronto, Ontario, Canada and Department of Psychiatry and Human Genetics, McGill University, Montreal, Quebec, Canada (R.M.P.)
| | - Roberta M Palmour
- Department of Pharmacology and Toxicology, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH) (Y.G., S.M., R.F.T.) and Department of Psychiatry (R.F.T.), University of Toronto, Toronto, Ontario, Canada and Department of Psychiatry and Human Genetics, McGill University, Montreal, Quebec, Canada (R.M.P.)
| | - Rachel F Tyndale
- Department of Pharmacology and Toxicology, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH) (Y.G., S.M., R.F.T.) and Department of Psychiatry (R.F.T.), University of Toronto, Toronto, Ontario, Canada and Department of Psychiatry and Human Genetics, McGill University, Montreal, Quebec, Canada (R.M.P.)
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18
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Borrego-Soto G, Perez-Paramo YX, Chen G, Santuario-Facio SK, Santos-Guzman J, Posadas-Valay R, Alvarado-Monroy FM, Balderas-Renteria I, Medina-Gonzalez R, Ortiz-Lopez R, Lazarus P, Rojas-Martinez A. Genetic variants in CYP2A6 and UGT1A9 genes associated with urinary nicotine metabolites in young Mexican smokers. THE PHARMACOGENOMICS JOURNAL 2020; 20:586-594. [PMID: 31959879 PMCID: PMC7375952 DOI: 10.1038/s41397-020-0147-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 12/19/2019] [Accepted: 01/07/2020] [Indexed: 12/24/2022]
Abstract
Nicotine is the major pharmacologically active substance in tobacco. Several studies have examined genotypes related to nicotine metabolism, but few studies have been performed in the Mexican population. The objective was to identify associations between gene variants in metabolizing enzymes and the urinary levels of nicotine metabolites among Mexican smokers. The levels of nicotine and its metabolites were determined in the urine of 88 young smokers from Mexico, and 167 variants in 24 genes associated with nicotine metabolism were genotyped by next-generation sequencing (NGS). Trans-3'-hydroxy-cotinine (3HC) and 4-hydroxy-4-(3-pyridyl)-butanoic acid were the most abundant metabolites (35 and 17%, respectively). CYP2A6*12 was associated with 3HC (p = 0.014). The rs145014075 was associated with creatinine-adjusted levels of nicotine (p = 0.035), while the rs12471326 (UGT1A9) was associated to cotinine-N-glucuronide (p = 0.030). CYP2A6 and UGT1A9 variants are associated to nicotine metabolism. 4HPBA metabolite was an abundant urinary metabolite in young Mexican smokers.
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Affiliation(s)
- Gissela Borrego-Soto
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Mexico
| | - Yadira X Perez-Paramo
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - Gang Chen
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | | | - Jesus Santos-Guzman
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Mexico
| | - Rodolfo Posadas-Valay
- Facultad de Medicina, Centro Universitario de Salud, Universidad Autonoma de Nuevo Leon, Monterrey, Mexico
| | | | | | - Ramses Medina-Gonzalez
- Centro de Investigación y Desarrollo en Ciencias de la Salud, Universidad Autonoma de Nuevo Leon, Monterrey, Mexico
| | - Rocio Ortiz-Lopez
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Mexico
| | - Philip Lazarus
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - Augusto Rojas-Martinez
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Mexico.
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Yang X, Naylor J, Matazel K, Goodwin A, Jacob CC, Bryant M, Loukotková L, Gamboa da Costa G, Chemerynski S, Deng-Bryant Y, Reissig C, Jackson K, Fisher J. Use of a physiologically-based pharmacokinetic model to explore the potential disparity in nicotine disposition between adult and adolescent nonhuman primates. Toxicol Appl Pharmacol 2020; 386:114826. [PMID: 31730783 DOI: 10.1016/j.taap.2019.114826] [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: 07/31/2019] [Revised: 10/23/2019] [Accepted: 11/11/2019] [Indexed: 10/25/2022]
Abstract
The widespread use and high abuse liability of tobacco products has received considerable public health attention, in particular for youth, who are vulnerable to nicotine addiction. In this study, adult and adolescent squirrel monkeys were used to evaluate age-related metabolism and pharmacokinetics of nicotine after intravenous administration. A physiologically-based pharmacokinetic (PBPK) model was created to characterize the pharmacokinetic behaviors of nicotine and its metabolites, cotinine, trans-3'-hydroxycotinine (3'-OH cotinine), and trans-3'-hydroxycotinine glucuronide (3'-OH cotinine glucuronide) for both adult and adolescent squirrel monkeys. The PBPK nicotine model was first calibrated for adult squirrel monkeys utilizing in vitro nicotine metabolic data, plasma concentration-time profiles and cumulative urinary excretion data for nicotine and metabolites. Further model refinement was conducted when the calibrated adult model was scaled to the adolescents, because adolescents appeared to clear nicotine and cotinine more rapidly relative to adults. More specifically, the resultant model parameters representing systemic clearance of nicotine and cotinine for adolescent monkeys were approximately two- to three-fold of the adult values on a per body weight basis. The nonhuman primate PBPK model in general captured experimental observations that were used for both model calibration and evaluation, with acceptable performance metrics for precision and bias. The model also identified differences in nicotine pharmacokinetics between adolescent and adult nonhuman primates which might also be present in humans.
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Affiliation(s)
- Xiaoxia Yang
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA.
| | - Jennifer Naylor
- Division of Neurotoxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
| | - Katelin Matazel
- Division of Neurotoxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
| | - Amy Goodwin
- Division of Neurotoxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
| | - Cristina C Jacob
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
| | - Matthew Bryant
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
| | - Lucie Loukotková
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
| | - Gonçalo Gamboa da Costa
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
| | - Susan Chemerynski
- Division of Nonclinical Science, Center for Tobacco Products, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Ying Deng-Bryant
- Division of Nonclinical Science, Center for Tobacco Products, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Chad Reissig
- Division of Individual Health Science, Center for Tobacco Products, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Kia Jackson
- Division of Individual Health Science, Center for Tobacco Products, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Jeffrey Fisher
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
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Dallmann A, Ince I, Coboeken K, Eissing T, Hempel G. A Physiologically Based Pharmacokinetic Model for Pregnant Women to Predict the Pharmacokinetics of Drugs Metabolized Via Several Enzymatic Pathways. Clin Pharmacokinet 2019; 57:749-768. [PMID: 28924743 DOI: 10.1007/s40262-017-0594-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Physiologically based pharmacokinetic modeling is considered a valuable tool for predicting pharmacokinetic changes in pregnancy to subsequently guide in-vivo pharmacokinetic trials in pregnant women. The objective of this study was to extend and verify a previously developed physiologically based pharmacokinetic model for pregnant women for the prediction of pharmacokinetics of drugs metabolized via several cytochrome P450 enzymes. METHODS Quantitative information on gestation-specific changes in enzyme activity available in the literature was incorporated in a pregnancy physiologically based pharmacokinetic model and the pharmacokinetics of eight drugs metabolized via one or multiple cytochrome P450 enzymes was predicted. The tested drugs were caffeine, midazolam, nifedipine, metoprolol, ondansetron, granisetron, diazepam, and metronidazole. Pharmacokinetic predictions were evaluated by comparison with in-vivo pharmacokinetic data obtained from the literature. RESULTS The pregnancy physiologically based pharmacokinetic model successfully predicted the pharmacokinetics of all tested drugs. The observed pregnancy-induced pharmacokinetic changes were qualitatively and quantitatively reasonably well predicted for all drugs. Ninety-seven percent of the mean plasma concentrations predicted in pregnant women fell within a twofold error range and 63% within a 1.25-fold error range. For all drugs, the predicted area under the concentration-time curve was within a 1.25-fold error range. CONCLUSION The presented pregnancy physiologically based pharmacokinetic model can quantitatively predict the pharmacokinetics of drugs that are metabolized via one or multiple cytochrome P450 enzymes by integrating prior knowledge of the pregnancy-related effect on these enzymes. This pregnancy physiologically based pharmacokinetic model may thus be used to identify potential exposure changes in pregnant women a priori and to eventually support informed decision making when clinical trials are designed in this special population.
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Affiliation(s)
- André Dallmann
- Department of Pharmaceutical and Medical Chemistry, Clinical Pharmacy, Westfälische Wilhelms-University Münster, 48149, Münster, Germany.
| | - Ibrahim Ince
- Clinical Pharmacometrics, Bayer AG, 51368, Leverkusen, Germany
| | - Katrin Coboeken
- Clinical Pharmacometrics, Bayer AG, 51368, Leverkusen, Germany
| | - Thomas Eissing
- Clinical Pharmacometrics, Bayer AG, 51368, Leverkusen, Germany
| | - Georg Hempel
- Department of Pharmaceutical and Medical Chemistry, Clinical Pharmacy, Westfälische Wilhelms-University Münster, 48149, Münster, Germany
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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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22
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Ho MF, Correia C, Ingle JN, Kaddurah-Daouk R, Wang L, Kaufmann SH, Weinshilboum RM. Ketamine and ketamine metabolites as novel estrogen receptor ligands: Induction of cytochrome P450 and AMPA glutamate receptor gene expression. Biochem Pharmacol 2018; 152:279-292. [PMID: 29621538 DOI: 10.1016/j.bcp.2018.03.032] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 03/30/2018] [Indexed: 12/21/2022]
Abstract
Major depressive disorder (MDD) is the most common psychiatric illness worldwide, and it displays a striking sex-dependent difference in incidence, with two thirds of MDD patients being women. Ketamine treatment can produce rapid antidepressant effects in MDD patients, effects that are mediated-at least partially-through glutamatergic neurotransmission. Two active metabolites of ketamine, (2R,6R)-hydroxynorketamine (HNK) and (2S,6S)-HNK, also appear to play a key role in ketamine's rapid antidepressant effects through the activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors. In the present study, we demonstrated that estrogen plus ketamine or estrogen plus active ketamine metabolites displayed additive effects on the induction of the expression of AMPA receptor subunits. In parallel, the expression of estrogen receptor alpha (ERα) was also significantly upregulated. Even more striking, radioligand binding assays demonstrated that [3H]-ketamine can directly bind to ERα (KD: 344.5 ± 13 nM). Furthermore, ketamine and its (2R,6R)-HNK and (2S,6S)-HNK metabolites displayed similar affinity for ERα (IC50: 2.31 ± 0.1, 3.40 ± 0.2, and 3.53 ± 0.2 µM, respectively) as determined by [3H]-ketamine displacement assays. Finally, induction of AMPA receptors by either estrogens or ketamine and its metabolites was lost when ERα was knocked down or silenced pharmacologically. These results suggest a positive feedback loop by which estrogens can augment the effects of ketamine and its (2R,6R)-HNK and (2S,6S)-HNK metabolites on the ERα-induced transcription of CYP2A6 and CYP2B6, estrogen inducible enzymes that catalyze ketamine's biotransformation to form the two active metabolites. These observations provide novel insight into ketamine's molecular mechanism(s) of action and have potential implications for the treatment of MDD.
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Affiliation(s)
- Ming-Fen Ho
- Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Cristina Correia
- Division of Oncology Research, Department of Oncology, Division of Hematology, Department of Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - James N Ingle
- Division of Medical Oncology, Department of Oncology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Rima Kaddurah-Daouk
- Department of Psychiatry and Behavioral Medicine, Duke Institute for Brain Sciences, Duke University, Durham, NC 27708, USA
| | - Liewei Wang
- Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Scott H Kaufmann
- Division of Oncology Research, Department of Oncology, Division of Hematology, Department of Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Richard M Weinshilboum
- Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
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23
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Tanner JA, Zhu AZ, Claw KG, Prasad B, Korchina V, Hu J, Doddapaneni H, Muzny DM, Schuetz EG, Lerman C, Thummel KE, Scherer SE, Tyndale RF. Novel CYP2A6 diplotypes identified through next-generation sequencing are associated with in-vitro and in-vivo nicotine metabolism. Pharmacogenet Genomics 2018; 28:7-16. [PMID: 29232328 PMCID: PMC5729933 DOI: 10.1097/fpc.0000000000000317] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES Smoking patterns and cessation rates vary widely across smokers and can be influenced by variation in rates of nicotine metabolism [i.e. cytochrome P450 2A6 (CYP2A6), enzyme activity]. There is high heritability of CYP2A6-mediated nicotine metabolism (60-80%) owing to known and unidentified genetic variation in the CYP2A6 gene. We aimed to identify and characterize additional genetic variants at the CYP2A6 gene locus. METHODS A new CYP2A6-specific sequencing method was used to investigate genetic variation in CYP2A6. Novel variants were characterized in a White human liver bank that has been extensively phenotyped for CYP2A6. Linkage and haplotype structure for the novel single nucleotide polymorphisms (SNPs) were assessed. The association between novel five-SNP diplotypes and nicotine metabolism rate was investigated. RESULTS Seven high-frequency (minor allele frequencies ≥6%) noncoding SNPs were identified as important contributors to CYP2A6 phenotypes in a White human liver bank (rs57837628, rs7260629, rs7259706, rs150298687 (also denoted rs4803381), rs56113850, rs28399453, and rs8192733), accounting for two times more variation in in-vitro CYP2A6 activity relative to the four established functional CYP2A6 variants that are frequently tested in Whites (CYP2A6*2, *4, *9, and *12). Two pairs of novel SNPs were in high linkage disequilibrium, allowing us to establish five-SNP diplotypes that were associated with CYP2A6 enzyme activity (rate of nicotine metabolism) in-vitro in the liver bank and in-vivo among smokers. CONCLUSION The novel five-SNP diplotype may be useful to incorporate into CYP2A6 genotype models for personalized prediction of nicotine metabolism rate, cessation success, and response to pharmacotherapies.
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Affiliation(s)
- Julie-Anne Tanner
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH)
- Department of Pharmacology and Toxicology
| | - Andy Z Zhu
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH)
- Department of Pharmacology and Toxicology
| | - Katrina G Claw
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | - Bhagwat Prasad
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | - Viktoriya Korchina
- Department of Molecular and Human Genetics, The Baylor College of Medicine Human Genome Sequencing Center, Houston, Texas, USA
| | - Jianhong Hu
- Department of Molecular and Human Genetics, The Baylor College of Medicine Human Genome Sequencing Center, Houston, Texas, USA
| | - HarshaVardhan Doddapaneni
- Department of Molecular and Human Genetics, The Baylor College of Medicine Human Genome Sequencing Center, Houston, Texas, USA
| | - Donna M Muzny
- Department of Molecular and Human Genetics, The Baylor College of Medicine Human Genome Sequencing Center, Houston, Texas, USA
| | - Erin G Schuetz
- Pharmaceutical Sciences Department, St Jude Children's Research Hospital, Memphis, Tennessee
| | - Caryn Lerman
- Department of Psychiatry, Annenberg School for Communication, and Abramson Cancer Center, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Kenneth E Thummel
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | - Steven E Scherer
- Department of Molecular and Human Genetics, The Baylor College of Medicine Human Genome Sequencing Center, Houston, Texas, USA
| | - Rachel F Tyndale
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH)
- Department of Pharmacology and Toxicology
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
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24
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Shahab L, Mortimer E, Bauld L, McGowan JA, McNeill A, Tyndale RF. Characterising the nicotine metabolite ratio and its association with treatment choice: A cross sectional analysis of Stop Smoking Services in England. Sci Rep 2017; 7:17613. [PMID: 29242560 PMCID: PMC5730579 DOI: 10.1038/s41598-017-17994-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 12/04/2017] [Indexed: 11/25/2022] Open
Abstract
Pharmacotherapy provision based on Nicotine Metabolite Ratio (NMR) status (slow/normal metabolism) may improve smoking cessation rates. However, it is unclear whether NMR status is consistent across patient characteristics and current treatment choice. Data come from 1,826 participants attending Stop Smoking Services (SSS) across England in 2012/13. Sociodemographic, mental/physical health, smoking and treatment characteristics (nicotine replacement therapy vs. other pharmacotherapy; group vs. one-to-one behavioural support) were assessed. Salivary nicotine metabolites were measured and NMR (3-hydroxycotinine/cotinine) computed, characterising smokers as slow (NMR < 0.31) or normal (NMR ≥ 0.31) metabolisers. Normal metabolisers were older than slow metabolisers (Odds Ratio (OR) = 1.49, 95% Confidence Interval (CI) = 1.32-1.69) but no other characteristics were associated with NMR status. Overall, predictors accounted for only 7.3% of NMR variance. In adjusted analysis, pharmacotherapy type was not associated with NMR status, but normal metabolisers were less likely to use group support (OR = 0.67, 95% CI = 0.51-0.89). NMR status does not vary substantially across sociodemographic characteristics. Given its impact on pharmacotherapy efficacy, the lack of an association with pharmacotherapy choice suggests there is scope to use NMR status to optimise the selection and efficacy of smoking cessation pharmacotherapy. The unexpected association of NMR status with behavioural support should be explored further.
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Affiliation(s)
- Lion Shahab
- Department of Behavioural Science and Health, University College London, London, UK.
- UK Centre for Tobacco and Alcohol Studies, Nottingham, UK.
| | - Emily Mortimer
- Department of Behavioural Science and Health, University College London, London, UK
| | - Linda Bauld
- UK Centre for Tobacco and Alcohol Studies, Nottingham, UK
- School of Health Sciences, University of Stirling, Scotland, Stirling, UK
| | - Jennifer A McGowan
- Department of Behavioural Science and Health, University College London, London, UK
| | - Ann McNeill
- UK Centre for Tobacco and Alcohol Studies, Nottingham, UK
- Addictions Department, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Rachel F Tyndale
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH) and Departments of Psychiatry, Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
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25
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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: 101] [Impact Index Per Article: 12.6] [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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26
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Jamwal R, Barlock BJ, Adusumalli S, Ogasawara K, Simons BL, Akhlaghi F. Multiplex and Label-Free Relative Quantification Approach for Studying Protein Abundance of Drug Metabolizing Enzymes in Human Liver Microsomes Using SWATH-MS. J Proteome Res 2017; 16:4134-4143. [PMID: 28944677 DOI: 10.1021/acs.jproteome.7b00505] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We describe a sequential windowed acquisition of all theoretical fragment ion mass spectra (SWATH-MS) based method for label-free, simultaneous, relative quantification of drug metabolism enzymes in human liver microsomes (HLM; n = 78). In-solution tryptic digestion was aided by a pressure cycling method, which allowed a 90 min incubation time, a significant reduction over classical protocols (12-18 h). Digested peptides were separated on an Acquity UHPLC Peptide BEH C18 column using a 60 min gradient method at a flow rate of 0.100 mL/min. The quadrupole-time-of-flight mass spectrometer (ESI-QTOFMS) was operated in positive electrospray ionization mode, and data were acquired by data-dependent acquisition (DDA) and SWATH-MSALL mode. A pooled HLM sample was used as a quality control to evaluate variability in digestion and quantification among different batches, and inter-batch %CV for various proteins was between 3.1 and 7.8%. Spectral library generated from the DDA data identified 1855 distinct proteins and 25 681 distinct peptides at a 1% global false discovery rate (FDR). SWATH data were queried and analyzed for 10 major cytochrome P450 (CYP) enzymes using Skyline, a targeted data extraction software. Further, correlation analysis was performed between functional activity, protein, and mRNA expression for ten CYP enzymes. Pearson correlation coefficient (r) between protein and activity for CYPs ranged from 0.314 (CYP2C19) to 0.767 (CYP2A6). A strong correlation was found between CYP3A4 and CYP3A5 abundance and activity determined using midazolam and testosterone (r > 0.600, p < 0.001). Protein-to-activity correlation was moderate (r > 0.400-0.600, p < 0.001) for CYP1A2, CYP2A6, CYP2B6, CYP2C9, and CYP2E1 and significant but poor (r < 0.400, p < 0.05) for CYP2C8, CYP2C19, and CYP2D6. The findings suggest the suitability of SWATH-MS based method as a valuable and relatively fast analytical technique for relative quantification of proteins in complex biological samples. We also show that protein abundance is a better surrogate than mRNA to predict the activity of CYP activity.
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Affiliation(s)
- Rohitash Jamwal
- Clinical Pharmacokinetics Research Laboratory, Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island , Kingston, Rhode Island 02881, United States
| | - Benjamin J Barlock
- Clinical Pharmacokinetics Research Laboratory, Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island , Kingston, Rhode Island 02881, United States
| | - Sravani Adusumalli
- Clinical Pharmacokinetics Research Laboratory, Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island , Kingston, Rhode Island 02881, United States
| | - Ken Ogasawara
- Clinical Pharmacokinetics Research Laboratory, Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island , Kingston, Rhode Island 02881, United States
| | | | - Fatemeh Akhlaghi
- Clinical Pharmacokinetics Research Laboratory, Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island , Kingston, Rhode Island 02881, United States
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Tanner JA, Henderson JA, Buchwald D, Howard BV, Henderson PN, Tyndale RF. 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 PMCID: PMC5382092 DOI: 10.1097/fpc.0000000000000271] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [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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Affiliation(s)
- Julie-Anne Tanner
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | | | - Dedra Buchwald
- Elson S. Floyd College of Medicine, Initiative for Research and Education to Advance Community Health (IREACH), Washington State University, Seattle, Washington
| | - Barbara V. Howard
- MedStar Health Research Institute, Hyattsville, Maryland; the Georgetown-Howard Universities Center for Clinical and Translational Sciences, Washington, District of Columbia
| | | | - Rachel F. Tyndale
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
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28
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Li S, Yang Y, Hoffmann E, Tyndale RF, Stein EA. CYP2A6 Genetic Variation Alters Striatal-Cingulate Circuits, Network Hubs, and Executive Processing in Smokers. Biol Psychiatry 2017; 81:554-563. [PMID: 27865452 PMCID: PMC5346346 DOI: 10.1016/j.biopsych.2016.09.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 09/10/2016] [Accepted: 09/14/2016] [Indexed: 12/21/2022]
Abstract
BACKGROUND Variation in the CYP2A6 gene alters the rate of nicotine metabolic inactivation and is associated with smoking behaviors and cessation success rates. The underlying neurobiological mechanisms of this genetic influence are unknown. METHODS Intrinsic functional connectivity strength, a whole-brain, data-driven, graph theory-based method, was applied to resting-state functional magnetic resonance imaging data in 66 smokers and 92 nonsmokers. A subset of subjects (n = 23/20; smokers/nonsmokers) performed the monetary incentive delay task, probing reward anticipation, and a go/no-go task, probing response inhibition, on two occasions, in the presence and absence of a nicotine patch. RESULTS A significant CYP2A6 genotype × smoking effect was found in the dorsal anterior cingulate cortex and ventral striatum, such that the normal (vs. slow) genotype individuals showed greater functional connectivity strength among smokers but not nonsmokers. Functional connectivity strength was negatively associated with severity of nicotine dependence in slow metabolizers. Both hubs were biased by inputs from the insula identified from seed-based connectivity. Similar gene × environment interactions were seen in ventral striatum during smoking abstinence when subjects performed the monetary incentive delay task and in dorsal anterior cingulate cortex when they performed the go/no-go task; both reductions were "normalized" in smokers (and increased in nonsmokers) after acute nicotine administration. CONCLUSIONS Because the CYP2A6 effect was seen only in smokers, these data suggest that the rate of nicotine metabolism-and thus the concentration of nicotine presented to the brain over the course of nicotine addiction-shapes brain circuits that, among other functions, compute reward and impulsivity processes.
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Affiliation(s)
- Sufang Li
- Neuroimaging Research Branch, NIDA-IRP, NIH, Baltimore, MD, USA
| | - Yihong Yang
- Neuroimaging Research Branch, NIDA-IRP, NIH, Baltimore, MD, USA
| | - Ewa Hoffmann
- Campbell Family Mental Health Research Institute of the Centre for Addiction and Mental Health and the Departments of Pharmacology & Toxicology, and Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Rachel F. Tyndale
- Campbell Family Mental Health Research Institute of the Centre for Addiction and Mental Health and the Departments of Pharmacology & Toxicology, and Psychiatry, University of Toronto, Toronto, ON, Canada,Corresponding authors. Elliot A. Stein, PhD, , Tel: (443)740-2650 Fax: (443)740-2734, 251 Bayview Blvd, Suite 200, Baltimore, MD 21224
| | - Elliot A. Stein
- Neuroimaging Research Branch, NIDA-IRP, NIH, Baltimore, MD, USA,Corresponding authors. Elliot A. Stein, PhD, , Tel: (443)740-2650 Fax: (443)740-2734, 251 Bayview Blvd, Suite 200, Baltimore, MD 21224
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29
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Tanner JA, Prasad B, Claw KG, Stapleton P, Chaudhry A, Schuetz EG, Thummel KE, Tyndale RF. Predictors of Variation in CYP2A6 mRNA, Protein, and Enzyme Activity in a Human Liver Bank: Influence of Genetic and Nongenetic Factors. J Pharmacol Exp Ther 2017; 360:129-139. [PMID: 27815364 PMCID: PMC5193072 DOI: 10.1124/jpet.116.237594] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 11/02/2016] [Indexed: 12/19/2022] Open
Abstract
Cytochrome P450 2A6 CYP2A6: metabolizes several clinically relevant substrates, including nicotine, the primary psychoactive component in cigarette smoke. Smokers vary widely in their rate of inactivation and clearance of nicotine, altering numerous smoking phenotypes. We aimed to characterize independent and shared impact of genetic and nongenetic sources of variation in CYP2A6 mRNA, protein, and enzyme activity in a human liver bank (n = 360). For the assessment of genetic factors, we quantified levels of CYP2A6, cytochrome P450 oxidoreductase (POR), and aldo-keto reductase 1D1 (AKR1D1) mRNA, and CYP2A6 and POR proteins. CYP2A6 enzyme activity was determined through measurement of cotinine formation from nicotine and 7-hydroxycoumarin formation from coumarin. Donor DNA was genotyped for CYP2A6, POR, and AKR1D1 genetic variants. Nongenetic factors assessed included gender, age, and liver disease. CYP2A6 phenotype measures were positively correlated to each other (r values ranging from 0.47-0.88, P < 0.001). Female donors exhibited higher CYP2A6 mRNA expression relative to males (P < 0.05). Donor age was weakly positively correlated with CYP2A6 protein (r = 0.12, P < 0.05) and activity (r = 0.20, P < 0.001). CYP2A6 reduced-function genotypes, but not POR or AKR1D1 genotypes, were associated with lower CYP2A6 protein (P < 0.001) and activity (P < 0.01). AKR1D1 mRNA was correlated with CYP2A6 mRNA (r = 0.57, P < 0.001), protein (r = 0.30, P < 0.001), and activity (r = 0.34, P < 0.001). POR protein was correlated with CYP2A6 activity (r = 0.45, P < 0.001). Through regression analyses, we accounted for 17% (P < 0.001), 37% (P < 0.001), and 77% (P < 0.001) of the variation in CYP2A6 mRNA, protein, and activity, respectively. Overall, several independent and shared sources of variation in CYP2A6 activity in vitro have been identified, which could translate to variable hepatic clearance of nicotine.
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Affiliation(s)
- Julie-Anne Tanner
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada (J-A.T., R.F.T.); Department of Pharmacology and Toxicology (J-A.T., R.F.T.) and Department of Psychiatry (R.F.T.), University of Toronto, Toronto, Ontario, Canada; Department of Pharmaceutics (B.P., K.G.C, K.E.T.) and Center for Exposures, Diseases, Genomics, and Environment (P.S.), University of Washington, Seattle, Washington; Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.C., E.G.S.)
| | - Bhagwat Prasad
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada (J-A.T., R.F.T.); Department of Pharmacology and Toxicology (J-A.T., R.F.T.) and Department of Psychiatry (R.F.T.), University of Toronto, Toronto, Ontario, Canada; Department of Pharmaceutics (B.P., K.G.C, K.E.T.) and Center for Exposures, Diseases, Genomics, and Environment (P.S.), University of Washington, Seattle, Washington; Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.C., E.G.S.)
| | - Katrina G Claw
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada (J-A.T., R.F.T.); Department of Pharmacology and Toxicology (J-A.T., R.F.T.) and Department of Psychiatry (R.F.T.), University of Toronto, Toronto, Ontario, Canada; Department of Pharmaceutics (B.P., K.G.C, K.E.T.) and Center for Exposures, Diseases, Genomics, and Environment (P.S.), University of Washington, Seattle, Washington; Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.C., E.G.S.)
| | - Patricia Stapleton
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada (J-A.T., R.F.T.); Department of Pharmacology and Toxicology (J-A.T., R.F.T.) and Department of Psychiatry (R.F.T.), University of Toronto, Toronto, Ontario, Canada; Department of Pharmaceutics (B.P., K.G.C, K.E.T.) and Center for Exposures, Diseases, Genomics, and Environment (P.S.), University of Washington, Seattle, Washington; Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.C., E.G.S.)
| | - Amarjit Chaudhry
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada (J-A.T., R.F.T.); Department of Pharmacology and Toxicology (J-A.T., R.F.T.) and Department of Psychiatry (R.F.T.), University of Toronto, Toronto, Ontario, Canada; Department of Pharmaceutics (B.P., K.G.C, K.E.T.) and Center for Exposures, Diseases, Genomics, and Environment (P.S.), University of Washington, Seattle, Washington; Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.C., E.G.S.)
| | - Erin G Schuetz
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada (J-A.T., R.F.T.); Department of Pharmacology and Toxicology (J-A.T., R.F.T.) and Department of Psychiatry (R.F.T.), University of Toronto, Toronto, Ontario, Canada; Department of Pharmaceutics (B.P., K.G.C, K.E.T.) and Center for Exposures, Diseases, Genomics, and Environment (P.S.), University of Washington, Seattle, Washington; Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.C., E.G.S.)
| | - Kenneth E Thummel
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada (J-A.T., R.F.T.); Department of Pharmacology and Toxicology (J-A.T., R.F.T.) and Department of Psychiatry (R.F.T.), University of Toronto, Toronto, Ontario, Canada; Department of Pharmaceutics (B.P., K.G.C, K.E.T.) and Center for Exposures, Diseases, Genomics, and Environment (P.S.), University of Washington, Seattle, Washington; Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.C., E.G.S.)
| | - Rachel F Tyndale
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada (J-A.T., R.F.T.); Department of Pharmacology and Toxicology (J-A.T., R.F.T.) and Department of Psychiatry (R.F.T.), University of Toronto, Toronto, Ontario, Canada; Department of Pharmaceutics (B.P., K.G.C, K.E.T.) and Center for Exposures, Diseases, Genomics, and Environment (P.S.), University of Washington, Seattle, Washington; Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.C., E.G.S.)
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30
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Rodríguez-Morató J, Robledo P, Tanner JA, Boronat A, Pérez-Mañá C, Oliver Chen CY, Tyndale RF, de la Torre R. CYP2D6 and CYP2A6 biotransform dietary tyrosol into hydroxytyrosol. Food Chem 2016; 217:716-725. [PMID: 27664690 DOI: 10.1016/j.foodchem.2016.09.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 05/31/2016] [Accepted: 09/05/2016] [Indexed: 11/29/2022]
Abstract
The dietary phenol tyrosol has been reported to be endogenously transformed into hydroxytyrosol, a potent antioxidant with multiple health benefits. In this work, we evaluated whether tyrosine hydroxylase (TH) and cytochrome P450s (CYPs) catalyzed this process. To assess TH involvement, Wistar rats were treated with α-methyl-L-tyrosine and tyrosol. Tyrosol was converted into hydroxytyrosol whilst α-methyl-L-tyrosine did not inhibit the biotransformation. The role of CYP was assessed in human liver microsomes (HLM) and tyrosol-to-hydroxytyrosol conversion was observed. Screening with selective enzymatic CYP inhibitors identified CYP2A6 as the major isoform involved in this process. Studies with baculosomes further demonstrated that CYP2D6 and CYP3A4 could transform tyrosol into hydroxytyrosol. Experiments using human genotyped livers showed an interindividual variability in hydroxytyrosol formation and supported findings that CYP2D6 and CYP2A6 mediated this reaction. The dietary health benefits of tyrosol-containing foods remain to be evaluated in light of CYP pharmacogenetics.
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Affiliation(s)
- Jose Rodríguez-Morató
- Integrative Pharmacology and Systems Neuroscience Research Group, Neurosciences Research Program, IMIM (Hospital del Mar Medical Research Institute), Dr. Aiguader 88, Barcelona 08003, Spain; Department of Experimental and Health Sciences, Universitat Pompeu Fabra (CEXS-UPF), Dr. Aiguader 80, Barcelona 08003, Spain; Spanish Biomedical Research Centre in Physiopathology of Obesity and Nutrition (CIBEROBN), Instituto Salud Carlos III, 28029 Madrid, Spain.
| | - Patricia Robledo
- Integrative Pharmacology and Systems Neuroscience Research Group, Neurosciences Research Program, IMIM (Hospital del Mar Medical Research Institute), Dr. Aiguader 88, Barcelona 08003, Spain; Department of Experimental and Health Sciences, Universitat Pompeu Fabra (CEXS-UPF), Dr. Aiguader 80, Barcelona 08003, Spain.
| | - Julie-Anne Tanner
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada; Department of Pharmacology and Toxicology, Toronto, Ontario, Canada.
| | - Anna Boronat
- Integrative Pharmacology and Systems Neuroscience Research Group, Neurosciences Research Program, IMIM (Hospital del Mar Medical Research Institute), Dr. Aiguader 88, Barcelona 08003, Spain; Department of Experimental and Health Sciences, Universitat Pompeu Fabra (CEXS-UPF), Dr. Aiguader 80, Barcelona 08003, Spain.
| | - Clara Pérez-Mañá
- Integrative Pharmacology and Systems Neuroscience Research Group, Neurosciences Research Program, IMIM (Hospital del Mar Medical Research Institute), Dr. Aiguader 88, Barcelona 08003, Spain; Department of Pharmacology, Therapeutics and Toxicology, Autonomous University of Barcelona, Cerdanyola, Spain.
| | - C-Y Oliver Chen
- Department of Pharmacology, Therapeutics and Toxicology, Autonomous University of Barcelona, Cerdanyola, Spain; Antioxidants Research Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, United States.
| | - Rachel F Tyndale
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada; Department of Pharmacology and Toxicology, Toronto, Ontario, Canada; Department of Psychiatry, Toronto, Ontario, Canada.
| | - Rafael de la Torre
- Integrative Pharmacology and Systems Neuroscience Research Group, Neurosciences Research Program, IMIM (Hospital del Mar Medical Research Institute), Dr. Aiguader 88, Barcelona 08003, Spain; Department of Experimental and Health Sciences, Universitat Pompeu Fabra (CEXS-UPF), Dr. Aiguader 80, Barcelona 08003, Spain; Spanish Biomedical Research Centre in Physiopathology of Obesity and Nutrition (CIBEROBN), Instituto Salud Carlos III, 28029 Madrid, Spain.
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Budzynska B, Skalicka-Wozniak K, Kruk-Slomka M, Wydrzynska-Kuzma M, Biala G. In vivo modulation of the behavioral effects of nicotine by the coumarins xanthotoxin, bergapten, and umbelliferone. Psychopharmacology (Berl) 2016; 233:2289-300. [PMID: 27080866 PMCID: PMC4873531 DOI: 10.1007/s00213-016-4279-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/14/2016] [Indexed: 12/14/2022]
Abstract
RATIONALE Nicotine, a dominant alkaloid found in tobacco, is responsible for physical dependence, as well as addiction to cigarette smoking; consequently, smoking cessation is a very difficult process. Hepatic cytochrome P-450 2A6 (CYP2A6) is involved in the 70-80 % of the initial metabolism of nicotine and its co-metabolites. As this metabolism is slowed by inhibitors of CYP2A6, this kind of enzymatic inhibition has been proposed as a novel target for smoking cessation. OBJECTIVES Nicotine administered alone improved memory acquisition and consolidation as well as exerted antidepressive activity in animal models. These effects persist for 24 h. However, they are completely extinguished 48 h after administration. METHODS To investigate if the coumarins prolong the behavioral effects of nicotine, the forced swimming test (FST)-animal models of depression, and passive avoidance (PA) test-memory and learning paradigm were used. RESULTS This study revealed that three CYP2A6 inhibitors: two furanocoumarins, xanthotoxin (15 mg/kg) and bergapten (25 mg/kg), and the simple coumarin umbelliferone (25 mg/kg), prolonged the antidepressive and procognitive effects of nicotine. CONCLUSIONS These natural products may offer a new approach to the treatment of nicotinism as antidepressant and memory improvement actions are one of the main factors of nicotine dependence.
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Affiliation(s)
- Barbara Budzynska
- Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, Lublin, Poland.
| | - Krystyna Skalicka-Wozniak
- />Department of Pharmacognosy with Medicinal Plants Unit, Medical University of Lublin, Lublin, Poland
| | - Marta Kruk-Slomka
- />Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, Lublin, Poland
| | | | - Grazyna Biala
- />Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, Lublin, Poland
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32
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Upreti VV, Wahlstrom JL. Meta-analysis of hepatic cytochrome P450 ontogeny to underwrite the prediction of pediatric pharmacokinetics using physiologically based pharmacokinetic modeling. J Clin Pharmacol 2015; 56:266-83. [DOI: 10.1002/jcph.585] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 06/29/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Vijay V. Upreti
- Clinical Pharmacology, Modeling and Simulation; Amgen, Inc.; South San Francisco CA USA
| | - Jan L. Wahlstrom
- Pharmacokinetics and Drug Metabolism; Amgen, Inc.; Thousand Oaks CA USA
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Nakano M, Fukushima Y, Yokota SI, Fukami T, Takamiya M, Aoki Y, Yokoi T, Nakajima M. CYP2A7 pseudogene transcript affects CYP2A6 expression in human liver by acting as a decoy for miR-126. Drug Metab Dispos 2015; 43:703-12. [PMID: 25710939 DOI: 10.1124/dmd.115.063255] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2025] Open
Abstract
Human cytochrome P450 (CYP)2A6 is responsible for the metabolic activation of tobacco-related nitrosamines, as well as the metabolism of nicotine and some pharmaceutical drugs. There are large interindividual differences in CYP2A6 activity and expression, largely attributed to genetic polymorphisms. However, the variability was observed within homozygotes of the wild-type CYP2A6 gene. In this study, we investigated the possibility that CYP2A6 might be regulated by microRNA. A luciferase assay revealed that a microRNA recognition element (MRE) of miR-126* found in the 3'-untranslated region (UTR) of CYP2A6 mRNA is functional. We established two HEK293 cell lines stably expressing CYP2A6, with one including and the other excluding the full-length 3'-UTR (HEK/2A6+UTR and HEK/2A6 cells, respectively). Overexpression of miR-126* markedly decreased CYP2A6 protein levels, enzyme activity, and mRNA level in HEK/2A6+UTR cells, whereas it marginally decreased those in HEK/2A6 cells, indicating that the 3'-UTR including the MRE is functional for the downregulation of CYP2A6 by miR-126*. The inhibition of miR-126* increased CYP2A6 protein levels in primary human hepatocytes, suggesting that miR-126* downregulates endogenous CYP2A6 expression. In 20 human liver samples, the expression ratios of CYP2A6 and a pseudogene transcript CYP2A7 mRNA were highly variable (CYP2A7/CYP2A6: 0.1 to 12). Interestingly, we found that CYP2A7 was another target of miR-126* and restored the miR-126*-dependent downregulation of CYP2A6 by acting as a decoy for miR-126*. In conclusion, this study demonstrates that human CYP2A6 is post-transcriptionally regulated by miR-126* and that CYP2A7 affects CYP2A6 expression by competing for miR-126* binding.
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Affiliation(s)
- Masataka Nakano
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences, Kanazawa University, Kakuma-machi, Kanazawa, Japan (M.Na., Y.F., S.-i.Y., T.F., T.Y., M.Ni.); Department of Legal Medicine, Iwate Medical University School of Medicine, Uchimaru, Morioka, Japan (M.T., Y.A.); and Department of Forensic Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Nagoya, Japan (Y.A.)
| | - Yasunari Fukushima
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences, Kanazawa University, Kakuma-machi, Kanazawa, Japan (M.Na., Y.F., S.-i.Y., T.F., T.Y., M.Ni.); Department of Legal Medicine, Iwate Medical University School of Medicine, Uchimaru, Morioka, Japan (M.T., Y.A.); and Department of Forensic Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Nagoya, Japan (Y.A.)
| | - Shin-ichi Yokota
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences, Kanazawa University, Kakuma-machi, Kanazawa, Japan (M.Na., Y.F., S.-i.Y., T.F., T.Y., M.Ni.); Department of Legal Medicine, Iwate Medical University School of Medicine, Uchimaru, Morioka, Japan (M.T., Y.A.); and Department of Forensic Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Nagoya, Japan (Y.A.)
| | - Tatsuki Fukami
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences, Kanazawa University, Kakuma-machi, Kanazawa, Japan (M.Na., Y.F., S.-i.Y., T.F., T.Y., M.Ni.); Department of Legal Medicine, Iwate Medical University School of Medicine, Uchimaru, Morioka, Japan (M.T., Y.A.); and Department of Forensic Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Nagoya, Japan (Y.A.)
| | - Masataka Takamiya
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences, Kanazawa University, Kakuma-machi, Kanazawa, Japan (M.Na., Y.F., S.-i.Y., T.F., T.Y., M.Ni.); Department of Legal Medicine, Iwate Medical University School of Medicine, Uchimaru, Morioka, Japan (M.T., Y.A.); and Department of Forensic Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Nagoya, Japan (Y.A.)
| | - Yasuhiro Aoki
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences, Kanazawa University, Kakuma-machi, Kanazawa, Japan (M.Na., Y.F., S.-i.Y., T.F., T.Y., M.Ni.); Department of Legal Medicine, Iwate Medical University School of Medicine, Uchimaru, Morioka, Japan (M.T., Y.A.); and Department of Forensic Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Nagoya, Japan (Y.A.)
| | - Tsuyoshi Yokoi
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences, Kanazawa University, Kakuma-machi, Kanazawa, Japan (M.Na., Y.F., S.-i.Y., T.F., T.Y., M.Ni.); Department of Legal Medicine, Iwate Medical University School of Medicine, Uchimaru, Morioka, Japan (M.T., Y.A.); and Department of Forensic Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Nagoya, Japan (Y.A.)
| | - Miki Nakajima
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences, Kanazawa University, Kakuma-machi, Kanazawa, Japan (M.Na., Y.F., S.-i.Y., T.F., T.Y., M.Ni.); Department of Legal Medicine, Iwate Medical University School of Medicine, Uchimaru, Morioka, Japan (M.T., Y.A.); and Department of Forensic Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Nagoya, Japan (Y.A.)
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Abstract
For the past 30 years, research examining predictors of successful smoking cessation treatment response has focused primarily on clinical variables, such as levels of tobacco dependence, craving, and self-efficacy. However, recent research has begun to determine biomarkers (such as genotype, nicotine and metabolite levels, and brain imaging findings) that may have utility in predicting smoking cessation. For genotype, genes associated with nicotinic acetylcholine receptors (nAChRs) and related proteins have been found to predict response to first-line medications (e.g. nicotine replacement therapy [NRT], bupropion, or varenicline) or quitting over time without a controlled treatment trial. For nicotine and metabolite levels, function of the cytochrome P450 2A6 liver enzyme, which can be assessed with the nicotine metabolite ratio or via genotype, has been found to predict response, with slow nicotine metabolizers having less severe nicotine dependence and a greater likelihood of quitting with NRT than normal metabolizers. For brain imaging, decreased activation of brain regions associated with emotion regulation and increased connectivity in emotion regulation networks, increased responsiveness to pleasant cues, and altered activation with the Stroop effect have been found in smokers who quit with the first-line medications listed above or counseling. In addition, our group recently demonstrated that lower pre-treatment brain nAChR density is associated with a greater chance of quitting smoking with NRT or placebo. Several of these studies found that specific biomarkers may provide additional information for predicting response beyond subjective symptom or rating scale measures, thereby giving an initial indication that biomarkers may, in the future, be useful for guiding smoking cessation treatment intensity, duration, and type.
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Akrodou YM. CYP2A6 Polymorphisms May Strengthen Individualized Treatment for Nicotine Dependence. SCIENTIFICA 2015; 2015:491514. [PMID: 26060595 PMCID: PMC4427762 DOI: 10.1155/2015/491514] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 03/27/2015] [Accepted: 04/06/2015] [Indexed: 06/04/2023]
Abstract
Each CYP2A6 gene variant metabolizes nicotine differently depending on its enzymatic activities. The normal nicotine metabolizer CYP2A6(*)1A is associated with high scores of nicotine dependence (5-10) on the Fagerström Test for Nicotine Dependence (FTND) scale because it encodes for enzymes that catalyze nicotine 100%. Slow nicotine metabolizers (i.e., CYP2A6(*)1H, CYP2A6(*)4A, CYP2A6(*)9, and CYP2A6(*)12A) are associated with underrated nicotine metabolizing activity (50%-75%), linking them to low scores for nicotine dependence (0-4) on the FTND scale. In a clinical trial involving the use of bupropion, people who were carriers of slow nicotine metabolizers were found to have a tendency to maintain abstinence 1.7 times longer than people with normal nicotine metabolizers. An overview of CYP2A6 polymorphism enzymatic activities in nicotine dependence etiology and treatment revealed that slow nicotine metabolizers may strengthen the individualized treatment of nicotine dependence.
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Affiliation(s)
- Yawo Mawuli Akrodou
- Department of Public Health, College of Health Sciences, Walden University, Minneapolis, MN 55401, USA
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36
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Variation in P450 oxidoreductase (POR) A503V and flavin-containing monooxygenase (FMO)-3 E158K is associated with minor alterations in nicotine metabolism, but does not alter cigarette consumption. Pharmacogenet Genomics 2014; 24:172-6. [PMID: 24448396 DOI: 10.1097/fpc.0000000000000031] [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
The rates of nicotine metabolism differ widely, even after controlling for genetic variation in the major nicotine-metabolizing enzyme, CYP2A6. Genetic variants in an additional nicotine-metabolizing enzyme, flavin-containing monooxygenase (FMO)-3, and an obligate microsomal CYP-supportive enzyme, cytochrome P450 oxidoreductase (POR), were investigated. We examined the impact of FMO3 E158K and POR A503V before and after stratifying by CYP2A6 metabolism group. In 130 nonsmokers of African descent who received 4 mg oral nicotine, FMO3 158K trended toward slower nicotine metabolism in reduced CYP2A6 metabolizers (P=0.07) only, whereas POR 503V was associated with faster CYP2A6 activity (nicotine metabolite ratio) in normal (P=0.03), but not reduced, CYP2A6 metabolizers. Neither FMO3 158K nor POR 503V significantly altered the nicotine metabolic ratio (N=659), cigarette consumption (N=667), or urine total nicotine equivalents (N=418) in smokers of African descent. Thus, FMO3 E158K and POR A503V are minor sources of nicotine metabolism variation, insufficient to appreciably alter smoking.
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Craig EL, Zhao B, Cui JZ, Novalen M, Miksys S, Tyndale RF. Nicotine pharmacokinetics in rats is altered as a function of age, impacting the interpretation of animal model data. Drug Metab Dispos 2014; 42:1447-55. [PMID: 24980255 PMCID: PMC4152873 DOI: 10.1124/dmd.114.058719] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 06/30/2014] [Indexed: 01/29/2023] Open
Abstract
Several behavioral studies report that adolescent rats display a preference for nicotine compared with adults. However, age-related pharmacokinetic differences may confound the interpretation of these findings. Thus, differences in pharmacokinetic analyses of nicotine were investigated. Nicotine was administered via acute s.c. (1.0 mg base/kg) or i.v. (0.2 mg base/kg) injection to early adolescent (EA; postnatal day 25) and adult (AD; postnatal day 71) male Wistar rats. Nicotine and its primary metabolite, cotinine, and additional metabolites nornicotine, nicotine-1'-N-oxide, trans-3'-hydroxycotinine, and norcotinine were sampled from 10 minutes to 8 hours (plasma) and 2 to 8 hours (brain) post nicotine and analyzed by liquid chromatography-tandem mass spectrometry. Following s.c. nicotine, the EA cohort had lower levels of plasma nicotine, cotinine, and nicotine-1'-N-oxide at multiple time points, resulting in a lower area under the plasma concentration-time curve (AUC) for nicotine (P < 0.001), cotinine (P < 0.01), and nicotine-1'-N-oxide (P < 0.001). Brain levels were also lower for these compounds. In contrast, the EA cohort had higher plasma and brain AUCs (P < 0.001) for the minor metabolite nornicotine. Brain-to-plasma ratios varied for nicotine and its metabolites, and by age. Following i.v. nicotine administration, similar age-related differences were observed, and this route allowed detection of a 1.6-fold-larger volume of distribution and 2-fold higher plasma clearance in the EA cohort compared with the AD cohort. Thus, unlike in humans, there are substantial age differences in nicotine pharmacokinetics such that for a given nicotine dose, adolescent rats will have lower plasma and brain nicotine compared with adults, suggesting that this should be considered when interpreting animal model data.
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Affiliation(s)
- Evelyn L Craig
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Departments of Pharmacology & Toxicology and Psychiatry, University of Toronto, Toronto, Ontario, Canada (E.L.C., B.Z., M.N., S.M., R.F.T.) and Child & Family Research Institute, Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada (J.Z.C.)
| | - Bin Zhao
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Departments of Pharmacology & Toxicology and Psychiatry, University of Toronto, Toronto, Ontario, Canada (E.L.C., B.Z., M.N., S.M., R.F.T.) and Child & Family Research Institute, Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada (J.Z.C.)
| | - Jason Z Cui
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Departments of Pharmacology & Toxicology and Psychiatry, University of Toronto, Toronto, Ontario, Canada (E.L.C., B.Z., M.N., S.M., R.F.T.) and Child & Family Research Institute, Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada (J.Z.C.)
| | - Maria Novalen
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Departments of Pharmacology & Toxicology and Psychiatry, University of Toronto, Toronto, Ontario, Canada (E.L.C., B.Z., M.N., S.M., R.F.T.) and Child & Family Research Institute, Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada (J.Z.C.)
| | - Sharon Miksys
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Departments of Pharmacology & Toxicology and Psychiatry, University of Toronto, Toronto, Ontario, Canada (E.L.C., B.Z., M.N., S.M., R.F.T.) and Child & Family Research Institute, Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada (J.Z.C.)
| | - Rachel F Tyndale
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Departments of Pharmacology & Toxicology and Psychiatry, University of Toronto, Toronto, Ontario, Canada (E.L.C., B.Z., M.N., S.M., R.F.T.) and Child & Family Research Institute, Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada (J.Z.C.)
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Vandenbergh DJ, Schlomer GL. Finding genomic function for genetic associations in nicotine addiction research: the ENCODE project's role in future pharmacogenomic analysis. Pharmacol Biochem Behav 2014; 123:34-44. [PMID: 24486638 PMCID: PMC4117825 DOI: 10.1016/j.pbb.2014.01.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 01/17/2014] [Accepted: 01/22/2014] [Indexed: 11/16/2022]
Abstract
Tobacco-related behaviors and the underlying addiction to nicotine are complex tangles of genetic and environmental factors. Efforts to understand the genetic component of these traits have identified sites in the genome (single nucleotide polymorphisms, or SNPs) that might account for some part of the role of genetics in nicotine addiction. Encouragingly, some of these candidate SNPs remain significant in meta-analyses. However, genetic associations cannot be fully assessed, regardless of statistical significance, without an understanding of the functional consequences of the alleles present at these SNPs. The proper experimental test for allelic function can be very difficult to define, representing a roadblock in translating genetic results into treatment to prevent smoking and other nicotine-related behaviors. This roadblock can be navigated in part with a new web-based tool, the Encyclopedia of DNA Elements (ENCODE). ENCODE is a compilation of searchable data on several types of biochemical functions or "marks" across the genome. These data can be queried for the co-localization of a candidate SNP and a biochemical mark. The presence of a SNP within a marked region of DNA enables the generation of better-informed hypotheses to test possible functional roles of alleles at a candidate SNP. Two examples of such co-localizations are presented. One example reveals ENCODE's ability to relate a candidate SNP's function with a gene very far from the physical location of the SNP. The second example reveals a new potential function of the SNP, rs4105144, that has been genetically associated with the number of cigarettes smoked per day. Details for accessing the ENCODE data for this SNP are provided to serve as a tutorial. By serving as a bridge between genetic associations and biochemical function, ENCODE has the power to propel progress in untangling the genetic aspects of nicotine addiction - a major public health concern.
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Affiliation(s)
- David J Vandenbergh
- Department of Biobehavioral Health, The Pennsylvania State University, 219 Biobehavioral Health Building, University Park, PA 16802, USA; Penn State Institute of the Neurosciences, 101 Life Sciences Building, University Park, PA 16802, USA.
| | - Gabriel L Schlomer
- Department of Human Development and Family Studies, The Pennsylvania State University, 315 Health and Human Development, East, University Park, PA 16802, USA.
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Li W, Ning M, Koh KH, Kim H, Jeong H. 17β-Estradiol induces sulfotransferase 2A1 expression through estrogen receptor α. Drug Metab Dispos 2014; 42:796-802. [PMID: 24492894 PMCID: PMC3965899 DOI: 10.1124/dmd.113.055178] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 02/03/2014] [Indexed: 01/02/2023] Open
Abstract
Sulfotransferase (SULT) 2A1 catalyzes sulfonation of drugs and endogenous compounds and plays an important role in xenobiotic metabolism as well as in the maintenance of steroid and lipid homeostasis. A recent study showed that 17β-estradiol (E2) increases the mRNA levels of SULT2A1 in human hepatocytes. Here we report the underlying molecular mechanisms. E2 enhanced SULT2A1 expression in human hepatocytes and HepG2-ER cells (HepG2 stably expressing ERα). SULT2A1 induction by E2 was abrogated by antiestrogen ICI 182,780, indicating a key role of ERα in the induction. Results from deletion and mutation assays of SULT2A1 promoter revealed three cis-elements located within -257/+140 region of SULT2A1 that are potentially responsible for the induction. Chromatin immunoprecipitation assay verified the recruitment of ERα to the promoter region. Electrophoretic mobility shift assays revealed that AP-1 proteins bind to one of the cis-elements. Interestingly, SULT2A1 promoter assays using ERα mutants revealed that the DNA-binding domain of ERα is indispensable for SULT2A1 induction by E2, suggesting that direct ERα binding to the SULT2A1 promoter is also necessary for the induction. Taken together, our results indicate that E2 enhances SULT2A1 expression by both the classical and nonclassical mechanisms of ERα action.
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Affiliation(s)
- Wei Li
- Department of Pharmacy Practice (W.L., K.H.K., H.K., H.J.) and Department of Biopharmaceutical Sciences (M.N., H.J.), College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois; and Medical College, Yangzhou University, Yangzhou, Jiangsu, China (W.L.)
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Saladores PH, Precht JC, Schroth W, Brauch H, Schwab M. Impact of metabolizing enzymes on drug response of endocrine therapy in breast cancer. Expert Rev Mol Diagn 2013; 13:349-65. [PMID: 23638818 DOI: 10.1586/erm.13.26] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Estrogen-receptor positive breast cancer accounts for 75% of diagnosed breast cancers worldwide. There are currently two major options for adjuvant treatment: tamoxifen and aromatase inhibitors. Variability in metabolizing enzymes determines their pharmacokinetic profile, possibly affecting treatment response. Therefore, prediction of therapy outcome based on genotypes would enable a more personalized medicine approach, providing optimal therapy for each patient. In this review, the authors will discuss the current evidence on the most important metabolizing enzymes in endocrine therapy, with a special focus on CYP2D6 and its role in tamoxifen metabolism.
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Affiliation(s)
- Pilar H Saladores
- Dr Margarete Fischer-Bosch-Institute of Clinical Pharmacology and University of Tübingen, Auerbachstr. 112, 70376 Stuttgart, Germany
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Vieira-Brock PL, Andrenyak DM, Nielsen SM, Fleckenstein AE, Wilkins DG. Age-related differences in the disposition of nicotine and metabolites in rat brain and plasma. Nicotine Tob Res 2013; 15:1839-48. [PMID: 23737496 DOI: 10.1093/ntr/ntt067] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
INTRODUCTION Studies have evaluated the behavioral and neurochemical impact of nicotine administration in rodents. However, the distribution of nicotine and metabolites in rat brain and plasma as a function of age has not been investigated. This is a significant issue because human adolescents have a greater risk for developing nicotine addiction than adults, and reasons underlying this observation have not been fully determined. Thus, in this present study, we evaluated the impact of the transition from adolescence (postnatal day [PND 40]) to adulthood (PND 90) on nicotine distribution in rats. METHODS PND 40, 60, and 90 rats received a single injection of (-) nicotine (0.8 mg/kg, subcutaneously). Liquid chromatography tandem-mass spectrometry was used to measure concentration of nicotine and metabolites in selected biological matrices. RESULTS Nicotine, cotinine, and nornicotine were detected in rat striata and frontal cortex 30 min, 1 hr, 2 hr, and 4 hr after a single administration. These and several additional metabolites (nicotine-1'-oxide, cotinine-N-oxide, norcotinine, and trans-3'-hydroxycotinine) were also detected in plasma at these same timepoints. The mean concentration of nicotine in brain and plasma was lower in PND 40 versus PND 90 rats. In contrast, the mean concentration of nornicotine was higher in the plasma and brain of PND 40 versus PND 90 rats. CONCLUSIONS Nicotine and metabolite distribution differs between adolescent and adult rats. These data suggest that adolescent rats metabolize nicotine to some metabolites faster than adult rats. Further studies are needed to investigate the potential correlation between age, drug distribution, and nicotine addiction.
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Affiliation(s)
- Paula L Vieira-Brock
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT
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Miksys S, Cappendijk SLT, Perry WM, Zhao B, Tyndale RF. Nicotine kinetics in zebra finches in vivo and in vitro. Drug Metab Dispos 2013; 41:1240-6. [PMID: 23530019 DOI: 10.1124/dmd.112.050765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nicotine enhances cognitive performance, and in the zebra finch (Taeniopygia guttata), which is a well-established model of cognition, the effects of nicotine on song production have been reported. Nicotine and cotinine plasma levels were assessed in vivo after subcutaneous injection of 0.18 mg/kg nicotine, a dose that elicits changes in song production. The half-life of nicotine elimination was 33 minutes, and levels were undetectable by 4 hours. Average plasma nicotine over 2 hours was 32 ng/ml, similar to levels seen in human smokers and rat models of nicotine behavior. Nicotine brain levels were 30 and 14 ng/g 1 and 2 hours after treatment. To understand the potential for drug interactions and the regulation of nicotine metabolism in zebra finches, we characterized in vitro nicotine metabolism and the hepatic enzyme involved. In humans, cytochrome P450 2A6 metabolizes nicotine to cotinine, and CYP2A-like activity and protein have been reported in some birds. Zebra finch liver microsomes metabolized nicotine and bupropion (a CYP2B substrate) but not coumarin (a CYP2A substrate). Nicotine was metabolized to cotinine with a Michaelis-Menten constant (K(m)) of 96 µM and a V(max) of 56 pmol/min per milligram. Nicotine and bupropion metabolism was inhibited by C-8-xanthate (a specific CYP2B inhibitor) but not by CYP2A-specific inhibitors, and hepatic levels of CYP2B-like but not CYP2A-like proteins correlated with nicotine (r = 0.52; P = 0.04) and bupropion metabolism (r = 0.81; P < 0.001), suggesting CYP2B-mediation of nicotine metabolism as seen in rats. These results will facilitate further investigation of nicotine's effects in zebra finches.
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Affiliation(s)
- Sharon Miksys
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Departments of Pharmacology and Toxicology and Psychiatry, University of Toronto, Toronto, Canada
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Dempsey DA, Sambol NC, Jacob P, Hoffmann E, Tyndale RF, Fuentes-Afflick E, Benowitz NL. CYP2A6 genotype but not age determines cotinine half-life in infants and children. Clin Pharmacol Ther 2013; 94:400-6. [PMID: 23714690 PMCID: PMC3820275 DOI: 10.1038/clpt.2013.114] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 05/19/2013] [Indexed: 01/08/2023]
Abstract
The formation of cotinine, the main proximate metabolite and a biomarker of nicotine exposure, is mediated primarily by cytochrome P450 (CYP)2A6. Our aim was to determine whether higher cotinine levels in young children exposed to secondhand smoke (SHS) are a result of age-related differences in pharmacokinetics. Forty-nine participants, aged 2-84 months, received oral deuterium-labeled cotinine, with daily urine samples for up to 10 days for cotinine half-life measurement. DNA from saliva was used for CYP2A6 genotyping. The estimate of half-life using a mixed-effect model was 17.9 h (95% confidence interval: 16.5, 19.3), similar to that reported in adults. There was no statistically significant effect of sex, race, age, or weight. Children with normal-activity CYP2A6*1/*1 genotypes had a shorter half-life than those with one or two reduced-activity variant alleles. Our data suggest that higher cotinine levels in SHS-exposed young children as compared with adults are due to greater SHS exposure rather than to different cotinine pharmacokinetics.
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Affiliation(s)
- D A Dempsey
- Division of Clinical Pharmacology and Experimental Therapeutics, Medical Service, San Francisco General Hospital Medical Center, San Francisco, California, USA
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Zhu AZX, Renner CC, Hatsukami DK, Swan GE, Lerman C, Benowitz NL, Tyndale RF. The ability of plasma cotinine to predict nicotine and carcinogen exposure is altered by differences in CYP2A6: the influence of genetics, race, and sex. Cancer Epidemiol Biomarkers Prev 2013; 22:708-18. [PMID: 23371292 DOI: 10.1158/1055-9965.epi-12-1234-t] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Cotinine, a nicotine metabolite, is a biomarker of tobacco, nicotine, and carcinogen exposure. However, a given cotinine level may not represent the same tobacco exposure; for example, African-Americans have higher cotinine levels than Caucasians after controlling for exposure. METHODS Cotinine levels are determined by the amount of cotinine formation and the rate of cotinine removal, which are both mediated by the enzyme CYP2A6. Because CYP2A6 activity differs by sex (estrogen induces CYP2A6) and genotype, their effect on cotinine formation and removal was measured in nonsmoking Caucasians (Study 1, n = 181) infused with labeled nicotine and cotinine. The findings were then extended to ad libitum smokers (Study 2, n = 163). RESULTS Study 1: Reduced CYP2A6 activity altered cotinine formation less than cotinine removal resulting in ratios of formation to removal of 1.31 and 1.12 in CYP2A6 reduced and normal metabolizers (P = 0.01), or 1.39 and 1.12 in males and females (P = 0.001), suggesting an overestimation of tobacco exposure in slower metabolizers. Study 2: Cotinine again overestimated tobacco and carcinogen exposure by 25% or more in CYP2A6 reduced metabolizers (≈2-fold between some genotypes) and in males. CONCLUSIONS In people with slower relative to faster CYP2A6 activity, cotinine accumulates resulting in substantial differences in cotinine levels for a given tobacco exposure. IMPACT Cotinine levels may be misleading when comparing those with differing CYP2A6 genotypes within a race, between races with differing frequencies of CYP2A6 gene variants (i.e., African-Americans have higher frequencies of reduced function variants contributing to their higher cotinine levels), or between the sexes.
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Affiliation(s)
- Andy Z X Zhu
- Departments of Psychiatry, Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
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Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variation. Pharmacol Ther 2013; 138:103-41. [PMID: 23333322 DOI: 10.1016/j.pharmthera.2012.12.007] [Citation(s) in RCA: 2719] [Impact Index Per Article: 226.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 12/27/2012] [Indexed: 02/06/2023]
Abstract
Cytochromes P450 (CYP) are a major source of variability in drug pharmacokinetics and response. Of 57 putatively functional human CYPs only about a dozen enzymes, belonging to the CYP1, 2, and 3 families, are responsible for the biotransformation of most foreign substances including 70-80% of all drugs in clinical use. The highest expressed forms in liver are CYPs 3A4, 2C9, 2C8, 2E1, and 1A2, while 2A6, 2D6, 2B6, 2C19 and 3A5 are less abundant and CYPs 2J2, 1A1, and 1B1 are mainly expressed extrahepatically. Expression of each CYP is influenced by a unique combination of mechanisms and factors including genetic polymorphisms, induction by xenobiotics, regulation by cytokines, hormones and during disease states, as well as sex, age, and others. Multiallelic genetic polymorphisms, which strongly depend on ethnicity, play a major role for the function of CYPs 2D6, 2C19, 2C9, 2B6, 3A5 and 2A6, and lead to distinct pharmacogenetic phenotypes termed as poor, intermediate, extensive, and ultrarapid metabolizers. For these CYPs, the evidence for clinical significance regarding adverse drug reactions (ADRs), drug efficacy and dose requirement is rapidly growing. Polymorphisms in CYPs 1A1, 1A2, 2C8, 2E1, 2J2, and 3A4 are generally less predictive, but new data on CYP3A4 show that predictive variants exist and that additional variants in regulatory genes or in NADPH:cytochrome P450 oxidoreductase (POR) can have an influence. Here we review the recent progress on drug metabolism activity profiles, interindividual variability and regulation of expression, and the functional and clinical impact of genetic variation in drug metabolizing P450s.
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Zhu AZ, Binnington MJ, Renner CC, Lanier AP, Hatsukami DK, Stepanov I, Watson CH, Sosnoff CS, Benowitz NL, Tyndale RF. Alaska Native smokers and smokeless tobacco users with slower CYP2A6 activity have lower tobacco consumption, lower tobacco-specific nitrosamine exposure and lower tobacco-specific nitrosamine bioactivation. Carcinogenesis 2013; 34:93-101. [PMID: 23027621 PMCID: PMC3534190 DOI: 10.1093/carcin/bgs306] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 09/18/2012] [Accepted: 09/23/2012] [Indexed: 11/15/2022] Open
Abstract
Nicotine, the psychoactive ingredient in tobacco, is metabolically inactivated by CYP2A6 to cotinine. CYP2A6 also activates procarcinogenic tobacco-specific nitrosamines (TSNA). Genetic variation in CYP2A6 is known to alter smoking quantity and lung cancer risk in heavy smokers. Our objective was to investigate how CYP2A6 activity influences tobacco consumption and procarcinogen levels in light smokers and smokeless tobacco users. Cigarette smokers (n = 141), commercial smokeless tobacco users (n = 73) and iqmik users (n = 20) were recruited in a cross-sectional study of Alaska Native people. The participants' CYP2A6 activity was measured by both endophenotype and genotype, and their tobacco and procarcinogen exposure biomarker levels were also measured. Smokers, smokeless tobacco users and iqmik users with lower CYP2A6 activity had lower urinary total nicotine equivalents (TNE) and (methylnitrosamino)-1-(3)pyridyl-1-butanol (NNAL) levels (a biomarker of TSNA exposure). Levels of N-nitrosonornicotine (NNN), a TSNA metabolically bioactivated by CYP2A6, were higher in smokers with lower CYP2A6 activities. Light smokers and smokeless tobacco users with lower CYP2A6 activity reduce their tobacco consumption in ways (e.g. inhaling less deeply) that are not reflected by self-report indicators. Tobacco users with lower CYP2A6 activity are exposed to lower procarcinogen levels (lower NNAL levels) and have lower procarcinogen bioactivation (as indicated by the higher urinary NNN levels suggesting reduced clearance), which is consistent with a lower risk of developing smoking-related cancers. This study demonstrates the importance of CYP2A6 in the regulation of tobacco consumption behaviors, procarcinogen exposure and metabolism in both light smokers and smokeless tobacco users.
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Affiliation(s)
- Andy Z.X. Zhu
- Centre for Addiction and Mental Health, Departments of Psychiatry, Pharmacology and Toxicology, University of Toronto, Toronto M5S 1A8, Ontario
| | - Matthew J. Binnington
- Centre for Addiction and Mental Health, Departments of Psychiatry, Pharmacology and Toxicology, University of Toronto, Toronto M5S 1A8, Ontario
| | - Caroline C. Renner
- Alaska Native Medical Center, Cardiology Research and Program Development, Anchorage, AK, USA
| | - Anne P. Lanier
- Alaska Native Medical Center, Cardiology Research and Program Development, Anchorage, AK, USA
| | | | - Irina Stepanov
- Division of Environmental Health Sciences and Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Clifford H. Watson
- United States Centers for Disease Control and Prevention, Atlanta, GA, USA and
| | - Connie S. Sosnoff
- United States Centers for Disease Control and Prevention, Atlanta, GA, USA and
| | - Neal L. Benowitz
- Division of Clinical Pharmacology, Departments of Medicine, Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
| | - Rachel F. Tyndale
- To whom correspondence should be addressed. Tel: +1 416 978 6374; Fax: +1 416 978 6395; E-mail:
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Ferguson CS, Miksys S, Palmour RM, Tyndale RF. Differential effects of nicotine treatment and ethanol self-administration on CYP2A6, CYP2B6 and nicotine pharmacokinetics in African green monkeys. J Pharmacol Exp Ther 2012; 343:628-37. [PMID: 22935730 DOI: 10.1124/jpet.112.198564] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2025] Open
Abstract
In primates, nicotine is metabolically inactivated in the liver by CYP2A6 and possibly CYP2B6. Changes in the levels of these two enzymes may affect nicotine pharmacokinetics and influence smoking behaviors. This study investigated the independent and combined effects of ethanol self-administration and nicotine treatment (0.5 mg/kg b.i.d. s.c.) on hepatic CYP2A6 and CYP2B6 levels (mRNA, protein, and enzymatic activity), in vitro nicotine metabolism, and in vivo nicotine pharmacokinetics in monkeys. CYP2A6 mRNA and protein levels and in vitro coumarin (selective CYP2A6 substrate) and nicotine metabolism were decreased by nicotine treatment but unaffected by ethanol. CYP2B6 protein levels and in vitro bupropion (selective CYP2B6 substrate) metabolism were increased by ethanol but unaffected by nicotine treatment; CYP2B6 mRNA levels were unaltered by either treatment. Combined ethanol and nicotine exposure decreased CYP2A6 mRNA and protein levels, as well as in vitro coumarin and nicotine metabolism, and increased CYP2B6 protein levels and in vitro bupropion metabolism, with no change in CYP2B6 mRNA levels. Chronic nicotine resulted in higher nicotine plasma levels achieved after nicotine administration, consistent with decreased CYP2A6. Ethanol alone, or combined with nicotine, resulted in lower nicotine plasma levels by a mechanism independent of the change in these enzymes. Thus, nicotine can decrease hepatic CYP2A6, reducing the metabolism of its substrates, including nicotine, whereas ethanol can increase hepatic CYP2B6, increasing the metabolism of CYP2B6 substrates. In vivo nicotine pharmacokinetics are differentially affected by ethanol and nicotine, but when both drugs are used in combination the effect more closely resembles ethanol alone.
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Affiliation(s)
- C S Ferguson
- Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology, and Toxicology, University of Toronto, Toronto, Canada
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Bloom AJ, Harari O, Martinez M, Madden PAF, Martin NG, Montgomery GW, Rice JP, Murphy SE, Bierut LJ, Goate A. Use of a predictive model derived from in vivo endophenotype measurements to demonstrate associations with a complex locus, CYP2A6. Hum Mol Genet 2012; 21:3050-62. [PMID: 22451501 DOI: 10.1093/hmg/dds114] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This study demonstrates a novel approach to test associations between highly heterogeneous genetic loci and complex phenotypes. Previous investigations of the relationship between Cytochrome P450 2A6 (CYP2A6) genotype and smoking phenotypes made comparisons by dividing subjects into broad categories based on assumptions that simplify the range of function of different CYP2A6 alleles, their numerous possible diplotype combinations and non-additive allele effects. A predictive model that translates CYP2A6 diplotype into a single continuous variable was previously derived from an in vivo metabolism experiment in 189 European Americans. Here, we apply this model to assess associations between genotype, inferred nicotine metabolism and smoking behaviors in larger samples without direct nicotine metabolism measurements. CYP2A6 genotype is not associated with nicotine dependence, as defined by the Fagerström Test of Nicotine Dependence, demonstrating that cigarettes smoked per day (CPD) and nicotine dependence have distinct genetic correlates. The predicted metric is significantly associated with CPD among African Americans and European American dependent smokers. Individual slow metabolizing genotypes are associated with lower CPD, but the predicted metric is the best predictor of CPD. Furthermore, optimizing the predictive model by including additional CYP2A6 alleles improves the fit of the model in an independent data set and provides a novel method of predicting the functional impact of alleles without direct metabolism measurements. Lastly, comprehensive genotyping and in vivo metabolism data are used to demonstrate that genome-wide significant associations between CPD and single nucleotide polymorphisms are the result of synthetic associations.
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Affiliation(s)
- A Joseph Bloom
- Department of Psychiatry, Washington University School of Medicine, 660 South Euclid, Saint Louis, MO 63119, USA.
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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: 70] [Impact Index Per Article: 5.0] [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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Positive and negative effects of alcohol and nicotine and their interactions: a mechanistic review. Neurotox Res 2011; 21:57-69. [PMID: 21932109 DOI: 10.1007/s12640-011-9275-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2011] [Revised: 08/14/2011] [Accepted: 08/31/2011] [Indexed: 12/30/2022]
Abstract
Nicotine and alcohol are two of the most commonly abused legal substances. Heavy use of one drug can often lead to, or is predictive of, heavy use of the other drug in adolescents and adults. Heavy drinking and smoking alone are of significant health hazard. The combination of the two, however, can result in synergistic adverse effects particularly in incidences of various cancers (e.g., esophagus). Although detrimental consequences of smoking are well established, nicotine by itself might possess positive and even therapeutic potential. Similarly, alcohol at low or moderated doses may confer beneficial health effects. These opposing findings have generated considerable interest in how these drugs act. Here we will briefly review the negative impact of drinking-smoking co-morbidity followed by factors that appear to contribute to the high rate of co-use of alcohol and nicotine. Our main focus will be on what research is telling us about the central actions and interactions of these drugs, and what has been elucidated about the mechanisms of their positive and negative effects. We will conclude by making suggestions for future research in this area.
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