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Perez-Paramo YX, Watson CJW, Chen G, Lazarus P. CYP2C19 Plays a Major Role in the Hepatic N-Oxidation of Cotinine. Drug Metab Dispos 2023; 51:29-37. [PMID: 35197312 PMCID: PMC9832378 DOI: 10.1124/dmd.121.000624] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 02/08/2022] [Accepted: 02/14/2022] [Indexed: 01/14/2023] Open
Abstract
The primary mode of metabolism of nicotine is via the formation of cotinine by the enzyme CYP2A6. Cotinine undergoes further CYP2A6-mediated metabolism by hydroxylation to 3-hydroxycotinine and norcotinine, but can also form cotinine-N-glucuronide and cotinine-N-oxide (COX). The goal of this study was to investigate the enzymes that catalyze COX formation and determine whether genetic variation in these enzymes may affect this pathway. Specific inhibitors of major hepatic cytochrome P450 (P450) enzymes were used in cotinine-N-oxidation reactions using pooled human liver microsomes (HLMs). COX formation was monitored by ultrahigh-pressure liquid chromatography-tandem mass spectrometry and enzyme kinetic analysis was performed using microsomes from P450-overexpressing human embryonic kidney 293 (HEK293) cell lines. Genotype-phenotype analysis was performed in a panel of 113 human liver specimens. Inhibition of COX formation was only observed in HLMs when using inhibitors of CYP2A6, CYP2B6, CYP2C19, CYP2E1, and CYP3A4. Microsomes from cells overexpressing CYP2A6 or CYP2C19 exhibited similar N-oxidation activity against cotinine, with maximum reaction rate over Michaelis constant values (intrinsic clearance) of 4.4 and 4.2 nL/min/mg, respectively. CYP2B6-, CYP2E1-, and CYP3A4-overexpressing microsomes were also active in COX formation. Significant associations (P < 0.05) were observed between COX formation and genetic variants in CYP2C19 (*2 and *17 alleles) in HLMs. These results demonstrate that genetic variants in CYP2C19 are associated with decreased COX formation, potentially affecting the relative levels of cotinine in the plasma or urine of smokers and ultimately affecting recommended smoking cessation therapies. SIGNIFICANCE STATEMENT: This study is the first to elucidate the enzymes responsible for cotinine-N-oxide formation and genetic variants that affect this biological pathway. Genetic variants in CYP2C19 have the potential to modify nicotine metabolic ratio in smokers and could affect pharmacotherapeutic decisions for smoking cessation treatments.
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Affiliation(s)
- Yadira X Perez-Paramo
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Christy J W Watson
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Gang Chen
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Philip Lazarus
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
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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: 0.7] [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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Perez-Paramo YX, Lazarus P. Pharmacogenetics factors influencing smoking cessation success; the importance of nicotine metabolism. Expert Opin Drug Metab Toxicol 2021; 17:333-349. [PMID: 33322962 PMCID: PMC8049967 DOI: 10.1080/17425255.2021.1863948] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 12/10/2020] [Indexed: 01/12/2023]
Abstract
Introduction: Smoking remains a worldwide epidemic, and despite an increase in public acceptance of the harms of tobacco use, it remains the leading cause of preventable death. It is estimated that up to 70% of all smokers express a desire to quit, but only 3-5% of them are successful.Areas covered: The goal of this review was to evaluate the current status of smoking cessation treatments and the feasibility of implementing personalized-medicine approaches to these pharmacotherapies. We evaluated the genetics associated with higher levels of nicotine addiction and follow with an analysis of the genetic variants that affect the nicotine metabolic ratio (NMR) and the FDA approved treatments for smoking cessation. We also highlighted the gaps in the process of translating current laboratory understanding into clinical practice, and the benefits of personalized treatment approaches for a successful smoking cessation strategy.Expert opinion: Evidence supports the use of tailored therapies to ensure that the most efficient treatments are utilized in an individual's smoking cessation efforts. An understanding of the genetic effects on the efficacy of individualized smoking cessation pharmacotherapies is key to smoking cessation, ideally utilizing a polygenetic risk score that considers all genetic variation.
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Affiliation(s)
- Yadira X. Perez-Paramo
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington, USA
| | - Philip Lazarus
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington, USA
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Gim JA, Kwon Y, Lee HA, Lee KR, Kim S, Choi Y, Kim YK, Lee H. A Machine Learning-Based Identification of Genes Affecting the Pharmacokinetics of Tacrolimus Using the DMET TM Plus Platform. Int J Mol Sci 2020; 21:E2517. [PMID: 32260456 PMCID: PMC7178269 DOI: 10.3390/ijms21072517] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 03/29/2020] [Accepted: 04/02/2020] [Indexed: 12/15/2022] Open
Abstract
Tacrolimus is an immunosuppressive drug with a narrow therapeutic index and larger interindividual variability. We identified genetic variants to predict tacrolimus exposure in healthy Korean males using machine learning algorithms such as decision tree, random forest, and least absolute shrinkage and selection operator (LASSO) regression. rs776746 (CYP3A5) and rs1137115 (CYP2A6) are single nucleotide polymorphisms (SNPs) that can affect exposure to tacrolimus. A decision tree, when coupled with random forest analysis, is an efficient tool for predicting the exposure to tacrolimus based on genotype. These tools are helpful to determine an individualized dose of tacrolimus.
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Affiliation(s)
- Jeong-An Gim
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 16229, Korea; (J.-A.G.); (Y.K.); (H.A.L.); (K.-R.L.); (S.K.)
- Medical Science Research Center, College of Medicine, Korea University, Seoul 02841, Korea
| | - Yonghan Kwon
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 16229, Korea; (J.-A.G.); (Y.K.); (H.A.L.); (K.-R.L.); (S.K.)
- Department of Biostatistics and Computing, Yonsei University Graduate School, Seoul 03722, Korea
| | - Hyun A Lee
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 16229, Korea; (J.-A.G.); (Y.K.); (H.A.L.); (K.-R.L.); (S.K.)
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul 03080, Korea
| | - Kyeong-Ryoon Lee
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 16229, Korea; (J.-A.G.); (Y.K.); (H.A.L.); (K.-R.L.); (S.K.)
- Laboratory Animal Resource Center, Korea Research Institute of Bioscience and Biotechnology, Ochang, Chungbuk 28116, Korea
| | - Soohyun Kim
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 16229, Korea; (J.-A.G.); (Y.K.); (H.A.L.); (K.-R.L.); (S.K.)
| | | | - Yu Kyong Kim
- Daewoong Pharmaceutical Co., Ltd., Seoul 06170, Korea;
| | - Howard Lee
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 16229, Korea; (J.-A.G.); (Y.K.); (H.A.L.); (K.-R.L.); (S.K.)
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul 03080, Korea
- Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 03080, Korea
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5
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Piebaldism: An Iranian case report carrying minor allele at rs999020 and rs1008658 SNPs of KIT gene. GENE REPORTS 2019. [DOI: 10.1016/j.genrep.2019.100544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Teitelbaum AM, Murphy SE, Akk G, Baker TB, Germann A, von Weymarn LB, Bierut LJ, Goate A, Kharasch ED, Bloom AJ. Nicotine dependence is associated with functional variation in FMO3, an enzyme that metabolizes nicotine in the brain. THE PHARMACOGENOMICS JOURNAL 2018; 18:136-143. [PMID: 28290528 PMCID: PMC5599305 DOI: 10.1038/tpj.2016.92] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 10/20/2016] [Accepted: 12/08/2016] [Indexed: 12/16/2022]
Abstract
A common haplotype of the flavin-containing monooxygenase gene FMO3 is associated with aberrant mRNA splicing, a twofold reduction in in vivo nicotine N-oxidation and reduced nicotine dependence. Tobacco remains the largest cause of preventable mortality worldwide. CYP2A6, the primary hepatic nicotine metabolism gene, is robustly associated with cigarette consumption but other enzymes contribute to nicotine metabolism. We determined the effects of common variants in FMO3 on plasma levels of nicotine-N-oxide in 170 European Americans administered deuterated nicotine. The polymorphism rs2266780 (E308G) was associated with N-oxidation of both orally administered and ad libitum smoked nicotine (P⩽3.3 × 10-5 controlling for CYP2A6 genotype). In vitro, the FMO3 G308 variant was not associated with reduced activity, but rs2266780 was strongly associated with aberrant FMO3 mRNA splicing in both liver and brain (P⩽6.5 × 10-9). Surprisingly, in treatment-seeking European American smokers (n=1558) this allele was associated with reduced nicotine dependence, specifically with a longer time to first cigarette (P=9.0 × 10-4), but not with reduced cigarette consumption. As N-oxidation accounts for only a small percentage of hepatic nicotine metabolism we hypothesized that FMO3 genotype affects nicotine metabolism in the brain (unlike CYP2A6, FMO3 is expressed in human brain) or that nicotine-N-oxide itself has pharmacological activity. We demonstrate for the first time nicotine N-oxidation in human brain, mediated by FMO3 and FMO1, and show that nicotine-N-oxide modulates human α4β2 nicotinic receptor activity in vitro. These results indicate possible mechanisms for associations between FMO3 genotype and smoking behaviors, and suggest nicotine N-oxidation as a novel target to enhance smoking cessation.
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Affiliation(s)
- A M Teitelbaum
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
| | - S E Murphy
- Department of Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - G Akk
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA.,Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA
| | - T B Baker
- Department of Psychology, University of Wisconsin, Madison, WI, USA
| | - A Germann
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA.,Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA
| | - L B von Weymarn
- Department of Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - L J Bierut
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - A Goate
- Neuroscience Genetics & Genomics Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - E D Kharasch
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
| | - A J Bloom
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA.,Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
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7
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Yuan JM, Nelson HH, Carmella SG, Wang R, Kuriger-Laber J, Jin A, Adams-Haduch J, Hecht SS, Koh WP, Murphy SE. CYP2A6 genetic polymorphisms and biomarkers of tobacco smoke constituents in relation to risk of lung cancer in the Singapore Chinese Health Study. Carcinogenesis 2017; 38:411-418. [PMID: 28182203 PMCID: PMC6248819 DOI: 10.1093/carcin/bgx012] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 01/16/2017] [Accepted: 01/24/2017] [Indexed: 01/01/2023] Open
Abstract
Cytochrome P450 2A6 (CYP2A6) catalyzes the metabolism of nicotine and the tobacco-specific lung carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Genetic variation in CYP2A6 may affect smoking behavior and contribute to lung cancer risk. A nested case-control study of 197 lung cancer cases and 197 matched controls was conducted within a prospective cohort of 63 257 Chinese men and women in Singapore. Quantified were five genetic variants of CYP2A6 (*1A, *4, *7, *9 and *12) and urinary metabolites of nicotine [total nicotine, total cotinine, total trans-3'-hydroxycotinine (3HC)] and NNK (total NNAL, free NNAL, NNAL-glucuronide, NNAL-N-glucuronide, and NNAL-O-glucuronide). Higher urinary metabolites of nicotine and NNK were significantly associated with a 2- to 3-fold increased risk of lung cancer after adjustment for smoking intensity and duration. Lower CYP2A6-determined nicotine metabolizer status was significantly associated with a lower ratio of total 3HC over total cotinine, lower total nicotine equivalent and reduced risk of developing lung cancer (all Ptrend < 0.001). Compared with normal metabolizers, odds ratios (95% confidence intervals) of developing lung cancer for intermediate, slow and poor metabolizers determined by CYP2A6 genotypes were 0.85 (0.41-1.77), 0.55 (0.28-1.08) and 0.32 (0.15-0.70), respectively, after adjustment for smoking intensity and duration and urinary total nicotine equivalents. Thus the reduced risk of lung cancer in smokers with lower CYP2A6 activity may be explained by lower consumption of cigarettes, less intense smoking and reduced CYP2A6-catalyzed activation of the tobacco-specific lung carcinogen NNK.
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Affiliation(s)
- Jian-Min Yuan
- Division of Cancer Control and Population Sciences, University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Heather H Nelson
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
- Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN, USA
| | - Steven G Carmella
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Renwei Wang
- Division of Cancer Control and Population Sciences, University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | | | - Aizhen Jin
- National Registry of Diseases Office, Health Promotion Board, Singapore, Singapore
| | - Jennifer Adams-Haduch
- Division of Cancer Control and Population Sciences, University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA
| | - Stephen S Hecht
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Woon-Puay Koh
- Duke-NUS Medical School Singapore, Singapore, Singapore
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore and
| | - Sharon E Murphy
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
- Department of Biochemistry, Molecular Biology and BioPhysics, University of Minnesota, MN, USA
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8
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He MM, Zhang DS, Wang F, Wang ZX, Yuan SQ, Wang ZQ, Luo HY, Ren C, Qiu MZ, Jin Y, Wang DS, Chen DL, Zeng ZL, Li YH, He YY, Hao YT, Guo P, Wang FH, Zeng YX, Xu RH. Phase II trial of S-1 plus leucovorin in patients with advanced gastric cancer and clinical prediction by S-1 pharmacogenetic pathway. Cancer Chemother Pharmacol 2016; 79:69-79. [PMID: 27913881 PMCID: PMC5225176 DOI: 10.1007/s00280-016-3209-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 11/24/2016] [Indexed: 01/10/2023]
Abstract
Background The first one-arm phase II trial aimed to evaluate and predict efficacy and safety of S-1 plus oral leucovorin (S-1/LV) as first-line chemotherapy for patients with advanced gastric cancer (AGC), using S-1 pharmacogenetic pathway approach. Patients and methods A total of 39 patients orally took S-1 at conventional dose and LV simultaneously at a dose of 25 mg twice daily for a week, within a 2-week cycle. The primary endpoint was overall response rate (ORR), while the secondary endpoints were progression-free survival (PFS), time to failure (TTF), overall survival (OS), disease control rate (DCR), and adverse events (AEs). Peripheral blood was sampled prospectively for baseline expression of dihydropyrimidine dehydrogenase (DPD), orotate phosphoribosyltransferase (OPRT), thymidine phosphorylase (TP), and thymidylate synthase (TS), CYP2A6 gene polymorphisms, and 5-FU pharmacokinetics. Results The ORR and DCR were 41.0 and 76.9%. The median PFS, TTF, and OS were 4.13, 3.70, and 11.40 months. Grade 3–4 AEs occurred in only 13 patients, and grade 4 AEs occurred in only 1 of them. High OPRT/TS and peritoneal metastasis (vs. liver metastasis) independently predicted responding. High OPRT/DPD independently predicted grade 3–4 AEs. High AUC0–24h of 5-FU and metastatic/recurrent sites ≤2 (vs. >3) independently predicted prolonged PFS. Low baseline plasmic DPD independently predicted prolonged OS. Conclusions Two-week, oral S-1/LV regimen demonstrated promising efficacy and safety as first-line chemotherapy for AGC. ClinicalTrials.gov identifier NCT02090153 Electronic supplementary material The online version of this article (doi:10.1007/s00280-016-3209-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ming-Ming He
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Dong-Sheng Zhang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Feng Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Zi-Xian Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Shu-Qiang Yuan
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Zhi-Qiang Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Hui-Yan Luo
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Chao Ren
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Miao-Zhen Qiu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Ying Jin
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - De-Shen Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Dong-Liang Chen
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Zhao-Lei Zeng
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Yu-Hong Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Yang-Yang He
- Beijing Key Laboratory of Drug Targets Identification and Drug Screening, Institute of Materia Medica, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Yuan-Tao Hao
- Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, China
| | - Pi Guo
- Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, China
| | - Feng-Hua Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China
| | - Yi-Xin Zeng
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China.,Beijing Hospital, Beijing, China
| | - Rui-Hua Xu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, China.
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9
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Yuan JM, Nelson HH, Butler LM, Carmella SG, Wang R, Kuriger-Laber JK, Adams-Haduch J, Hecht SS, Gao YT, Murphy SE. Genetic determinants of cytochrome P450 2A6 activity and biomarkers of tobacco smoke exposure in relation to risk of lung cancer development in the Shanghai cohort study. Int J Cancer 2016; 138:2161-71. [PMID: 26662855 PMCID: PMC5155585 DOI: 10.1002/ijc.29963] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 11/30/2015] [Indexed: 11/06/2022]
Abstract
Cytochrome P450 2A6 (CYP2A6) catalyzes nicotine metabolism and contributes to the metabolism of the tobacco-specific lung carcinogen, NNK. Genetic variation in CYP2A6 may affect smoking behavior and contribute to lung cancer risk. A nested case-control study of 325 lung cancer cases and 356 controls was conducted within a prospective cohort of 18,244 Chinese men in Shanghai, China. Quantified were 4 allelic variants of CYP2A6 [*1(+51A), *4, *7, and *9] and urinary total nicotine, total cotinine, total trans-3'-hydroxycotinine (3HC) and total NNAL (an NNK metabolite). Calculated were total nicotine equivalents (TNE), the sum of total nicotine, total cotinine and total 3HC and the total 3HC:total cotinine ratio as a measure of CYP2A6 activity. The nicotine metabolizer status (normal, intermediate, slow and poor) was determined by CYP2A6 genotypes. The smoking-adjusted odds ratios (95% confidence intervals) of lung cancer for the highest vs lowest quartile of total nicotine, total cotinine, total 3HC, TNE and total NNAL were 3.03 (1.80-5.10), 4.70 (2.61-8.46), 4.26 (2.37-7.68), 4.71 (2.61-8.52), and 3.15 (1.86-5.33) (all Ptrend < 0.001), respectively. Among controls CYP2A6 poor metabolizers had a 78% lower total 3HC:total cotinine ratio and 72% higher total nicotine (Ptrend ≤ 0.002). Poor metabolizers had an odds ratio of 0.64 (95% confidence interval = 0.43-0.97) for lung cancer, which was statistically nonsignificant (odds ratio = 0.74, 95% confidence interval = 0.48-1.15) after adjustment for urinary TNE and smoking intensity and duration. The lower lung cancer risk observed in CYP2A6 poor metabolizers is partially explained by the strong influence of CYP2A6 genetic polymorphisms on nicotine uptake and metabolism.
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Affiliation(s)
- Jian-Min Yuan
- Division of Cancer Control and Population Sciences, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania, USA
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Heather H. Nelson
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, USA
- Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, USA
| | - Lesley M. Butler
- Division of Cancer Control and Population Sciences, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania, USA
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Steven G. Carmella
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, USA
| | - Renwei Wang
- Division of Cancer Control and Population Sciences, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania, USA
| | | | - Jennifer Adams-Haduch
- Division of Cancer Control and Population Sciences, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania, USA
| | - Stephen S. Hecht
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, USA
| | - Yu-Tang Gao
- Department of Epidemiology, Shanghai Cancer Institute, Shanghai Jiaotong University, Shanghai, China
| | - Sharon E. Murphy
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, USA
- Department of Biochemistry, Molecular Biology and BioPhysics, University of Minnesota, Minneapolis, USA
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10
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Park SL, Tiirikainen MI, Patel YM, Wilkens LR, Stram DO, Le Marchand L, Murphy SE. Genetic determinants of CYP2A6 activity across racial/ethnic groups with different risks of lung cancer and effect on their smoking intensity. Carcinogenesis 2016; 37:269-279. [PMID: 26818358 DOI: 10.1093/carcin/bgw012] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 01/19/2016] [Indexed: 01/22/2023] Open
Abstract
Genetic variation in cytochrome P450 2A6 (CYP2A6) gene is the primary contributor to the intraindividual and interindividual differences in nicotine metabolism and has been found to influence smoking intensity. However, no study has evaluated the relationship between CYP2A6 genetic variants and the CYP2A6 activity ratio (total 3-hydroxycotinine/cotinine) and their influence on smoking intensity [total nicotine equivalents (TNE)], across five racial/ethnic groups found to have disparate rates of lung cancer. This study genotyped 10 known functional CYP2A6 genetic or copy number variants in 2115 current smokers from the multiethnic cohort study [African Americans (AA) = 350, Native Hawaiians (NH) = 288, Whites = 413, Latinos (LA) = 437 and Japanese Americans (JA) = 627] to conduct such an investigation. Here, we found that LA had the highest CYP2A6 activity followed by Whites, AA, NH and JA, who had the lowest levels. Adjusting for age, sex, race/ethnicity and body mass index, we found that CYP2A6 diplotypes were predictive of TNE levels, particularly in AA and JA (P trend < 0.0001). However, only in JA did the association remain after accounting for cigarettes per day. Also, it is only in this population that the lower activity ratio supports lower TNE levels, carcinogen exposure and thereby lower risk of lung cancer. Despite the association between nicotine metabolism (CYP2A6 activity phenotype and diplotypes) and smoking intensity (TNE), CYP2A6 levels did not correlate with the higher TNE levels found in AA nor the lower TNE levels found in LA, suggesting that other factors may influence smoking dose in these populations. Therefore, further study in these populations is recommended.
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Affiliation(s)
| | - Maarit I Tiirikainen
- Epidemiology Program, University of Hawaii Cancer Center , Honolulu, HI 96813 , USA and
| | | | - Lynne R Wilkens
- Epidemiology Program, University of Hawaii Cancer Center , Honolulu, HI 96813 , USA and
| | | | - Loic Le Marchand
- Epidemiology Program, University of Hawaii Cancer Center , Honolulu, HI 96813 , USA and
| | - Sharon E Murphy
- Department of Biochemistry, Molecular Biology and Biophysics, Masonic Cancer Center, University of Minnesota , 2231 6th Street SE, 2-127 CCRB, Minneapolis, MN 55455 , USA
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11
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Bergen AW, Michel M, Nishita D, Krasnow R, Javitz HS, Conneely KN, Lessov-Schlaggar CN, Hops H, Zhu AZX, Baurley JW, McClure JB, Hall SM, Baker TB, Conti DV, Benowitz NL, Lerman C, Tyndale RF, Swan GE. Drug Metabolizing Enzyme and Transporter Gene Variation, Nicotine Metabolism, Prospective Abstinence, and Cigarette Consumption. PLoS One 2015; 10:e0126113. [PMID: 26132489 PMCID: PMC4488893 DOI: 10.1371/journal.pone.0126113] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Accepted: 03/29/2015] [Indexed: 11/28/2022] Open
Abstract
The Nicotine Metabolite Ratio (NMR, ratio of trans-3’-hydroxycotinine and cotinine), has previously been associated with CYP2A6 activity, response to smoking cessation treatments, and cigarette consumption. We searched for drug metabolizing enzyme and transporter (DMET) gene variation associated with the NMR and prospective abstinence in 2,946 participants of laboratory studies of nicotine metabolism and of clinical trials of smoking cessation therapies. Stage I was a meta-analysis of the association of 507 common single nucleotide polymorphisms (SNPs) at 173 DMET genes with the NMR in 449 participants of two laboratory studies. Nominally significant associations were identified in ten genes after adjustment for intragenic SNPs; CYP2A6 and two CYP2A6 SNPs attained experiment-wide significance adjusted for correlated SNPs (CYP2A6 PACT=4.1E-7, rs4803381 PACT=4.5E-5, rs1137115, PACT=1.2E-3). Stage II was mega-regression analyses of 10 DMET SNPs with pretreatment NMR and prospective abstinence in up to 2,497 participants from eight trials. rs4803381 and rs1137115 SNPs were associated with pretreatment NMR at genome-wide significance. In post-hoc analyses of CYP2A6 SNPs, we observed nominally significant association with: abstinence in one pharmacotherapy arm; cigarette consumption among all trial participants; and lung cancer in four case:control studies. CYP2A6 minor alleles were associated with reduced NMR, CPD, and lung cancer risk. We confirmed the major role that CYP2A6 plays in nicotine metabolism, and made novel findings with respect to genome-wide significance and associations with CPD, abstinence and lung cancer risk. Additional multivariate analyses with patient variables and genetic modeling will improve prediction of nicotine metabolism, disease risk and smoking cessation treatment prognosis.
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Affiliation(s)
- Andrew W. Bergen
- Center for Health Sciences, SRI International, Menlo Park, California, United States of America
- * E-mail:
| | - Martha Michel
- Academic Research Systems, University of California San Francisco, San Francisco, California, United States of America
| | - Denise Nishita
- Center for Health Sciences, SRI International, Menlo Park, California, United States of America
| | - Ruth Krasnow
- Center for Health Sciences, SRI International, Menlo Park, California, United States of America
| | - Harold S. Javitz
- Center for Health Sciences, SRI International, Menlo Park, California, United States of America
| | - Karen N. Conneely
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | | | - Hyman Hops
- Oregon Research Institute, Eugene, Oregon, United States of America
| | - Andy Z. X. Zhu
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | | | - Jennifer B. McClure
- Group Health Research Institute, Seattle, Washington, United States of America
| | - Sharon M. Hall
- Department of Psychiatry, University of California San Francisco, San Francisco, California, United States of America
| | - Timothy B. Baker
- Center for Tobacco Research and Intervention, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - David V. Conti
- Department of Preventive Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Neal L. Benowitz
- Departments of Medicine and of Bioengineering & Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Caryn Lerman
- Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Rachel F. Tyndale
- Cambell Family Mental Health Research Institute, Centre for Addiction and Mental Health, and Departments of Psychiatry, and of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Gary E. Swan
- Oregon Research Institute, Eugene, Oregon, United States of America
- Stanford Prevention Research Center, Department of Medicine, Stanford University School of Medicine, Palo Alto, California, United States of America
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12
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Novel CYP2A6 variants identified in African Americans are associated with slow nicotine metabolism in vitro and in vivo. Pharmacogenet Genomics 2014; 24:118-28. [PMID: 24305170 DOI: 10.1097/fpc.0000000000000026] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Nicotine, the main addictive ingredient in tobacco, is metabolically inactivated to cotinine primarily by the hepatic enzyme CYP2A6. Considerable genetic variation in the CYP2A6 gene results in large variation in the rates of nicotine metabolism, which in turn alters smoking behaviours (e.g. amount of cigarettes smoked, risk for dependence and success in smoking cessation). The aim of this study was to identify and characterize novel variants in CYP2A6. MATERIALS AND METHODS The CYP2A6 gene from African American phenotypically slow nicotine metabolizers was sequenced and seven novel variants were identified [CYP2A6*39 (V68M), CYP2A6*40 (I149M), CYP2A6*41 (R265Q), CYP2A6*42 (I268T), CYP2A6*43 (T303I), CYP2A6*44 (E390K), CYP2A6*44 (L462P)]. Variants were introduced into a bi-cistronic cDNA expression construct containing CYP2A6 and P450 oxidoreductase and assessed for protein expression, enzymatic activity and stability as evaluated using western blotting and nicotine metabolism. Genotyping assays were developed and allelic frequencies were assessed in 534 African Americans. RESULTS The variants showed significantly lower protein expression (P<0.001) when compared with the wild-type as well as reduced metabolism of nicotine to cotinine when controlling for cDNA expression using P450 oxidoreductase (P<0.001). The variants also showed reduced stability at 37°C. Allelic frequencies ranged from 0.1 to 0.6% with a collective genotype frequency of 3.2%; the impact in vitro correlated significantly with in-vivo activity (R(2)=0.40-0.48, P<0.05). Together, those with a novel variant had significantly lower nicotine metabolism in vivo than those without genetic variants (P<0.01). CONCLUSION Here, we identified a number of novel variants with reduced/loss of CYP2A6 activity, increasing our understanding of CYP2A6 genetic variability.
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The contribution of common UGT2B10 and CYP2A6 alleles to variation in nicotine glucuronidation among European Americans. Pharmacogenet Genomics 2014; 23:706-16. [PMID: 24192532 DOI: 10.1097/fpc.0000000000000011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND To develop a predictive genetic model of nicotine metabolism. UDP-glucuronosyltransferase-2B10 (UGT2B10) is the primary catalyst of nicotine glucuronidation. MATERIALS AND METHODS The conversion of deuterated (D2)-nicotine to D2-nicotine-glucuronide, D2-cotinine, D2-cotinine-glucuronide, and D2-trans-3'-hydroxycotinine were quantified in 188 European Americans, and the contribution of UGT2B10 genotype to variability in first-pass nicotine glucuronidation assessed, following a procedure previously applied to nicotine C-oxidation. The proportion of total nicotine converted to nicotine-glucuronide [D2-nicotine-glucuronide/(D2-nicotine+D2-nicotine-glucuronide+D2-cotinine+D2-cotinine-glucuronide+D2-trans-3'-hydroxycotinine)] was the primary phenotype. RESULTS The variant, rs61750900T (D67Y) (minor allele frequency=10%), is confirmed to abolish nicotine glucuronidation activity. Another variant, rs112561475G (N397D) (minor allele frequency=2%), is significantly associated with enhanced glucuronidation. rs112561475G is the ancestral allele of a well-conserved amino acid, indicating that the majority of human UGT2B10 alleles are derived hypomorphic alleles. CONCLUSION CYP2A6 and UGT2B10 genotype explain 53% of the variance in oral nicotine glucuronidation in this sample. CYP2A6 and UGT2B10 genetic variants are also significantly associated with undeuterated (D0) nicotine glucuronidation in individuals smoking ad libitum. We find no evidence for further common variation markedly influencing hepatic UGT2B10 expression in European Americans.
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Bloom AJ, Martinez M, Chen LS, Bierut LJ, Murphy SE, Goate A. CYP2B6 non-coding variation associated with smoking cessation is also associated with differences in allelic expression, splicing, and nicotine metabolism independent of common amino-acid changes. PLoS One 2013; 8:e79700. [PMID: 24260284 PMCID: PMC3829832 DOI: 10.1371/journal.pone.0079700] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 10/04/2013] [Indexed: 11/23/2022] Open
Abstract
The Cytochrome P450 2B6 (CYP2B6) enzyme makes a small contribution to hepatic nicotine metabolism relative to CYP2A6, but CYP2B6 is the primary enzyme responsible for metabolism of the smoking cessation drug bupropion. Using CYP2A6 genotype as a covariate, we find that a non-coding polymorphism in CYP2B6 previously associated with smoking cessation (rs8109525) is also significantly associated with nicotine metabolism. The association is independent of the well-studied non-synonymous variants rs3211371, rs3745274, and rs2279343 (CYP2B6*5 and *6). Expression studies demonstrate that rs8109525 is also associated with differences in CYP2B6 mRNA expression in liver biopsy samples. Splicing assays demonstrate that specific splice forms of CYP2B6 are associated with haplotypes defined by variants including rs3745274 and rs8109525. These results indicate differences in mRNA expression and splicing as potential molecular mechanisms by which non-coding variation in CYP2B6 may affect enzymatic activity leading to differences in metabolism and smoking cessation.
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Affiliation(s)
- A. Joseph Bloom
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
| | - Maribel Martinez
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Li-Shiun Chen
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Laura J. Bierut
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Sharon E. Murphy
- Department of Biochemistry Molecular Biology and BioPhysics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Alison Goate
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, United States of America
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15
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Bloom AJ, Baker TB, Chen LS, Breslau N, Hatsukami D, Bierut LJ, Goate A. Variants in two adjacent genes, EGLN2 and CYP2A6, influence smoking behavior related to disease risk via different mechanisms. Hum Mol Genet 2013; 23:555-61. [PMID: 24045616 DOI: 10.1093/hmg/ddt432] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Genome-wide significant associations with cigarettes per day (CPD) and risk for lung cancer and chronic obstructive pulmonary disease (COPD) were previously reported in a region of 19q13, including CYP2A6 (nicotine metabolism enzyme) and EGLN2 (hypoxia response). The associated single nucleotide polymorphisms (SNPs) were assumed to be proxies for functional variation in CYP2A6. Here, we demonstrate that when CYP2A6 and EGLN2 genotypes are analyzed together, the key EGLN2 variant, rs3733829, is not associated with nicotine metabolism independent of CYP2A6, but is nevertheless independently associated with CPD, and with breath carbon monoxide (CO), a phenotype associated with cigarette consumption and relevant to hypoxia. SNPs in EGLN2 are also associated with nicotine dependence and with smoking efficiency (CO/CPD). These results indicate a previously unappreciated novel mechanism behind genome-wide significant associations with cigarette consumption and disease risk unrelated to nicotine metabolism.
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Affiliation(s)
- A Joseph Bloom
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
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