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Characterization of the novel CYP2A6*21 allele using in vivo nicotine kinetics

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Abstract

Objective

The impact of CYP2A6*21 (K476R) on in vivo nicotine metabolism and disposition was investigated.

Methods

A two-step allele-specific PCR assay was developed to detect the 6573A>G single nucleotide polymorphism (SNP) in CYP2A6*21. Nicotine metabolism phenotypes from a previously described intravenous labeled nicotine and cotinine infusion study [1] was used to assess the impact of CYP2A6*21. Genomic DNA samples from 222 (111 monozygotic and dizygotic twin pairs) Caucasian subjects were genotyped for CYP2A6 alleles (CYP2A6*1X2, -*1B, -*2, -*4, -*7, -*9, -*10, -*12, and -*21). The pharmacokinetic parameters were compared between individuals with no detected CYP2A6 variants (CYP2A6*1/*1, n=163) and individuals heterozygous for the CYP2A6*21 allele (CYP2A6*1/*21, n=9).

Results

The frequency of the CYP2A6*21 allele was found to be 2.3% in Caucasians (n=5/222 alleles, evaluated in one twin from each twin pair). In vivo pharmacokinetic parameters, such as nicotine clearance (1.32±0.37 vs. 1.18±0.20 L/min), fractional clearance of nicotine to cotinine (1.02±0.36 vs. 0.99±0.23 L/min), nicotine half-life (111±37 vs. 116±29 min), and the trans-3′-hydroxycotinine to cotinine ratio (1.92±1.0 vs. 1.55±0.58) indicated no substantial differences in nicotine metabolism between those without the variant (CYP2A6*1/*1, n=163) and those with the variant (CYP2A6*1/*21, n=9), respectively.

Conclusions

CYP2A6*21 does not have a detectable impact on nicotine metabolism in vivo. Our data suggest that CYP2A6*21 may not be important for future studies of nicotine metabolism and the resulting impacts on smoking behaviors.

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References

  1. Swan GE, Benowitz NL, Jacob P 3rd, Lessov CN, Tyndale RF, Wilhelmsen K, Krasnow RE, McElroy MR, Moore SE, Wambach M (2004) Pharmacogenetics of nicotine metabolism in twins: methods and procedures. Twin Res 7:435

    Article  PubMed  Google Scholar 

  2. Messina ES, Tyndale RF, Sellers EM (1997) A major role for CYP2A6 in nicotine C-oxidation by human liver microsomes. J Pharmacol Exp Ther 282:1608

    PubMed  CAS  Google Scholar 

  3. Nakajima M, Yamamoto T, Nunoya K, Yokoi T, Nagashima K, Inoue K, Funae Y, Shimada N, Kamataki T, Kuroiwa Y (1996) Role of human cytochrome P4502A6 in C-oxidation of nicotine. Drug Metab Dispos 24:1212

    PubMed  CAS  Google Scholar 

  4. Benowitz NL, Jacob P 3rd (1994) Metabolism of nicotine to cotinine studied by a dual stable isotope method. Clin Pharmacol Ther 56:483

    Article  PubMed  CAS  Google Scholar 

  5. Gu DF, Hinks LJ, Morton NE, Day IN (2000) The use of long PCR to confirm three common alleles at the CYP2A6 locus and the relationship between genotype and smoking habit. Ann Hum Genet 64:383

    Article  PubMed  CAS  Google Scholar 

  6. O’Loughlin J, Paradis G, Kim W, DiFranza J, Meshefedjian G, McMillan-Davey E, Wong S, Hanley J, Tyndale RF (2004) Genetically decreased CYP2A6 and the risk of tobacco dependence: a prospective study of novice smokers. Tob Control 13:422

    Article  PubMed  CAS  Google Scholar 

  7. Rao Y, Hoffmann E, Zia M, Bodin L, Zeman M, Sellers EM, Tyndale RF (2000) Duplications and defects in the CYP2A6 gene: identification, genotyping, and in vivo effects on smoking. Mol Pharmacol 58:747

    PubMed  CAS  Google Scholar 

  8. Schoedel KA, Hoffmann EB, Rao Y, Sellers EM, Tyndale RF (2004) Ethnic variation in CYP2A6 and association of genetically slow nicotine metabolism and smoking in adult Caucasians. Pharmacogenetics 14:615

    Article  PubMed  CAS  Google Scholar 

  9. Haberl M, Anwald B, Klein K, Weil R, Fuss C, Gepdiremen A, Zanger UM, Meyer UA, Wojnowski L (2005) Three haplotypes associated with CYP2A6 phenotypes in Caucasians. Pharmacogenet Genomics 15:609

    Article  PubMed  CAS  Google Scholar 

  10. Lewis DF, Lake BG, Dickins M, Goldfarb PS (2003) Homology modelling of CYP2A6 based on the CYP2C5 crystallographic template: enzyme-substrate interactions and QSARs for binding affinity and inhibition. Toxicol In Vitro 17:179

    Article  PubMed  CAS  Google Scholar 

  11. Mwenifumbo JC, Myers MG, Wall TL, Lin SK, Sellers EM, Tyndale RF (2005) Ethnic variation in CYP2A6*7, CYP2A6*8 and CYP2A6*10 as assessed with a novel haplotyping method. Pharmacogenet Genomics 15:189

    Article  PubMed  CAS  Google Scholar 

  12. Oscarson M, McLellan RA, Gullsten H, Agundez JA, Benitez J, Rautio A, Raunio H, Pelkonen O, Ingelman-Sundberg M (1999) Identification and characterisation of novel polymorphisms in the CYP2A locus: implications for nicotine metabolism. FEBS Lett 460:321

    Article  PubMed  CAS  Google Scholar 

  13. Kim D, Wu ZL, Guengerich FP (2005) Analysis of Coumarin 7-Hydroxylation Activity of Cytochrome P450 2A6 using Random Mutagenesis. J Biol Chem 280:40319

    Article  PubMed  CAS  Google Scholar 

  14. Solus JF, Arietta BJ, Harris JR, Sexton DP, Steward JQ, McMunn C, Ihrie P, Mehall JM, Edwards TL, Dawson EP (2004) Genetic variation in eleven phase I drug metabolism genes in an ethnically diverse population. Pharmacogenomics 5:895

    Article  PubMed  CAS  Google Scholar 

  15. Swan GE, Benowitz NL, Lessov CN, Jacob P 3rd, Tyndale RF, Wilhelmsen K (2005) Nicotine metabolism: the impact of CYP2A6 on estimates of additive genetic influence. Pharmacogenet Genomics 15:115

    Article  PubMed  CAS  Google Scholar 

  16. Lewis DF, Dickins M, Lake BG, Eddershaw PJ, Tarbit MH, Goldfarb PS (1999) Molecular modelling of the human cytochrome P450 isoform CYP2A6 and investigations of CYP2A substrate selectivity. Toxicology 133:1

    Article  PubMed  CAS  Google Scholar 

  17. Yano JK, Hsu MH, Griffin KJ, Stout CD, Johnson EF (2005) Structures of human microsomal cytochrome P450 2A6 complexed with coumarin and methoxsalen. Nat Struct Mol Biol 12:822

    Article  PubMed  CAS  Google Scholar 

  18. Xu C, Rao YS, Xu B, Hoffmann E, Jones J, Sellers EM, Tyndale RF (2002) An in vivo pilot study characterizing the new CYP2A6*7, *8, and *10 alleles. Biochem Biophys Res Commun 290:318

    Article  PubMed  CAS  Google Scholar 

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Acknowledgements

The authors wish to thank Dr. L. Ashworth (Human genome center, Liverpool) for generously providing us with Cosmid DNA clones 19296, 19019, and 27292 that contain CYP2A6, CYP2A7, and CYP2A13, respectively. We sincerely thank Dr. Jason Yano for his helpful comments on the position and potential impact of CYP2A6*21 using the CYP2A6 crystal structure. We thank Drs. T. Inaba and E. Roberts for providing the human livers that provided data used as part of the rationale for this study. We are grateful for the participation of the twins without whom this work would not have been possible. CIHR, The Centre for Addiction & Mental Health and US Public Health Service grants awarded by the National Institutes on Drug Abuse, and carried out in part at the General Clinical Research Center at San Francisco General Hospital with support of the Division of Research Resources MOP-53248, DA11170, DA02277, DA12393 and NIH RR00083 supported this study. NA receives funding from CIHR-STPTR and OGS, JCM receives funding from CIHR-STPTR and SPICE, and RFT holds a Canadian Research Chair in Pharmacogenetics. All experiments conducted are in compliance with the current laws of U.S.A. and Canada inclusive of ethics approval.

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Correspondence to Rachel F. Tyndale.

Additional information

Nael Al Koudsi and Jill C. Mwenifumbo contributed equally to this work.

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Al Koudsi, N., Mwenifumbo, J.C., Sellers, E.M. et al. Characterization of the novel CYP2A6*21 allele using in vivo nicotine kinetics. Eur J Clin Pharmacol 62, 481–484 (2006). https://doi.org/10.1007/s00228-006-0113-3

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  • DOI: https://doi.org/10.1007/s00228-006-0113-3

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