The L84F polymorphism in the O6-methylguanine-DNA-methyltransferase (MGMT) gene is associated with increased hypoxanthine phosphoribosyltransferase (HPRT) mutant frequency in lymphocytes of tobacco smokers

Courtney E. Hill, Jeffrey K. Wickliffe, Adele T. Guerin, Carla J. Kinslow, Kevin J. Wolfe, Marinel M. Ammenheuser, Sherif Abdel-Rahman

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

OBJECTIVES: O-methylguanine-DNA-methyltransferase (MGMT) is a crucial DNA repair protein that removes DNA adducts formed by alkylating mutagens. Several coding single nucleotide polymorphisms (cSNPs) in the MGMT gene have been reported. Their biological significance, however, is not known. METHODS: We used a newly modified cloning HPRT mutant lymphocyte assay to test the hypothesis that inheritance of the L84F and I143V coding single nucleotide polymorphism in the MGMT gene is associated with increases in HPRT mutant frequency in lymphocytes of individuals exposed to alkylating agents. In addition, we expanded and sequenced 109 mutant clones to test the hypothesis that the mutation spectrum would shift to a larger percentage of base substitutions and G→A transition mutations in cells with L84F and I143 V coding single nucleotide polymorphisms. RESULTS: We observed no significant effect for the I143 V coding single nucleotide polymorphism on mutant frequency. In contrast, we observed a significant increase in mutant frequency (P<0.01) in lymphocytes from smokers with the 84F coding single nucleotide polymorphism compared with smokers homozygous for the referent L84 wild-type allele. A multiple regression analysis indicated that the mutant frequency increased significantly as a function of the 84F coding single nucleotide polymorphism and smoking, according to the model; mutant frequency (×10)=0.90+0.618 (84F polymorphism)+0.46 (smoking) with R=0.22. Mutation spectra analysis revealed an apparent increase, which was short of statistical significance (P=0.08), in base substitutions in cells with the 84F polymorphism. CONCLUSIONS: These new data suggest that the 84F coding single nucleotide polymorphism may alter the phenotype of the MGMT protein, resulting in suboptimal repair of O-methylguanine lesions after exposure to alkylating agents.

Original languageEnglish (US)
Pages (from-to)743-753
Number of pages11
JournalPharmacogenetics and Genomics
Volume17
Issue number9
DOIs
StatePublished - Sep 2007

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Hypoxanthine Phosphoribosyltransferase
Methyltransferases
Tobacco
Single Nucleotide Polymorphism
Lymphocytes
DNA
Genes
Alkylating Agents
Mutation
Smoking
Protein Methyltransferases
DNA Adducts
Mutagens
O-(6)-methylguanine
DNA Repair
Organism Cloning
Spectrum Analysis
Clone Cells
Alleles
Regression Analysis

Keywords

  • Biomarkers
  • Cancer
  • DNA repair
  • HPRT
  • MGMT
  • Mutation
  • Polymorphism
  • Smoking

ASJC Scopus subject areas

  • Genetics
  • Pharmacology

Cite this

The L84F polymorphism in the O6-methylguanine-DNA-methyltransferase (MGMT) gene is associated with increased hypoxanthine phosphoribosyltransferase (HPRT) mutant frequency in lymphocytes of tobacco smokers. / Hill, Courtney E.; Wickliffe, Jeffrey K.; Guerin, Adele T.; Kinslow, Carla J.; Wolfe, Kevin J.; Ammenheuser, Marinel M.; Abdel-Rahman, Sherif.

In: Pharmacogenetics and Genomics, Vol. 17, No. 9, 09.2007, p. 743-753.

Research output: Contribution to journalArticle

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title = "The L84F polymorphism in the O6-methylguanine-DNA-methyltransferase (MGMT) gene is associated with increased hypoxanthine phosphoribosyltransferase (HPRT) mutant frequency in lymphocytes of tobacco smokers",
abstract = "OBJECTIVES: O-methylguanine-DNA-methyltransferase (MGMT) is a crucial DNA repair protein that removes DNA adducts formed by alkylating mutagens. Several coding single nucleotide polymorphisms (cSNPs) in the MGMT gene have been reported. Their biological significance, however, is not known. METHODS: We used a newly modified cloning HPRT mutant lymphocyte assay to test the hypothesis that inheritance of the L84F and I143V coding single nucleotide polymorphism in the MGMT gene is associated with increases in HPRT mutant frequency in lymphocytes of individuals exposed to alkylating agents. In addition, we expanded and sequenced 109 mutant clones to test the hypothesis that the mutation spectrum would shift to a larger percentage of base substitutions and G→A transition mutations in cells with L84F and I143 V coding single nucleotide polymorphisms. RESULTS: We observed no significant effect for the I143 V coding single nucleotide polymorphism on mutant frequency. In contrast, we observed a significant increase in mutant frequency (P<0.01) in lymphocytes from smokers with the 84F coding single nucleotide polymorphism compared with smokers homozygous for the referent L84 wild-type allele. A multiple regression analysis indicated that the mutant frequency increased significantly as a function of the 84F coding single nucleotide polymorphism and smoking, according to the model; mutant frequency (×10)=0.90+0.618 (84F polymorphism)+0.46 (smoking) with R=0.22. Mutation spectra analysis revealed an apparent increase, which was short of statistical significance (P=0.08), in base substitutions in cells with the 84F polymorphism. CONCLUSIONS: These new data suggest that the 84F coding single nucleotide polymorphism may alter the phenotype of the MGMT protein, resulting in suboptimal repair of O-methylguanine lesions after exposure to alkylating agents.",
keywords = "Biomarkers, Cancer, DNA repair, HPRT, MGMT, Mutation, Polymorphism, Smoking",
author = "Hill, {Courtney E.} and Wickliffe, {Jeffrey K.} and Guerin, {Adele T.} and Kinslow, {Carla J.} and Wolfe, {Kevin J.} and Ammenheuser, {Marinel M.} and Sherif Abdel-Rahman",
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T1 - The L84F polymorphism in the O6-methylguanine-DNA-methyltransferase (MGMT) gene is associated with increased hypoxanthine phosphoribosyltransferase (HPRT) mutant frequency in lymphocytes of tobacco smokers

AU - Hill, Courtney E.

AU - Wickliffe, Jeffrey K.

AU - Guerin, Adele T.

AU - Kinslow, Carla J.

AU - Wolfe, Kevin J.

AU - Ammenheuser, Marinel M.

AU - Abdel-Rahman, Sherif

PY - 2007/9

Y1 - 2007/9

N2 - OBJECTIVES: O-methylguanine-DNA-methyltransferase (MGMT) is a crucial DNA repair protein that removes DNA adducts formed by alkylating mutagens. Several coding single nucleotide polymorphisms (cSNPs) in the MGMT gene have been reported. Their biological significance, however, is not known. METHODS: We used a newly modified cloning HPRT mutant lymphocyte assay to test the hypothesis that inheritance of the L84F and I143V coding single nucleotide polymorphism in the MGMT gene is associated with increases in HPRT mutant frequency in lymphocytes of individuals exposed to alkylating agents. In addition, we expanded and sequenced 109 mutant clones to test the hypothesis that the mutation spectrum would shift to a larger percentage of base substitutions and G→A transition mutations in cells with L84F and I143 V coding single nucleotide polymorphisms. RESULTS: We observed no significant effect for the I143 V coding single nucleotide polymorphism on mutant frequency. In contrast, we observed a significant increase in mutant frequency (P<0.01) in lymphocytes from smokers with the 84F coding single nucleotide polymorphism compared with smokers homozygous for the referent L84 wild-type allele. A multiple regression analysis indicated that the mutant frequency increased significantly as a function of the 84F coding single nucleotide polymorphism and smoking, according to the model; mutant frequency (×10)=0.90+0.618 (84F polymorphism)+0.46 (smoking) with R=0.22. Mutation spectra analysis revealed an apparent increase, which was short of statistical significance (P=0.08), in base substitutions in cells with the 84F polymorphism. CONCLUSIONS: These new data suggest that the 84F coding single nucleotide polymorphism may alter the phenotype of the MGMT protein, resulting in suboptimal repair of O-methylguanine lesions after exposure to alkylating agents.

AB - OBJECTIVES: O-methylguanine-DNA-methyltransferase (MGMT) is a crucial DNA repair protein that removes DNA adducts formed by alkylating mutagens. Several coding single nucleotide polymorphisms (cSNPs) in the MGMT gene have been reported. Their biological significance, however, is not known. METHODS: We used a newly modified cloning HPRT mutant lymphocyte assay to test the hypothesis that inheritance of the L84F and I143V coding single nucleotide polymorphism in the MGMT gene is associated with increases in HPRT mutant frequency in lymphocytes of individuals exposed to alkylating agents. In addition, we expanded and sequenced 109 mutant clones to test the hypothesis that the mutation spectrum would shift to a larger percentage of base substitutions and G→A transition mutations in cells with L84F and I143 V coding single nucleotide polymorphisms. RESULTS: We observed no significant effect for the I143 V coding single nucleotide polymorphism on mutant frequency. In contrast, we observed a significant increase in mutant frequency (P<0.01) in lymphocytes from smokers with the 84F coding single nucleotide polymorphism compared with smokers homozygous for the referent L84 wild-type allele. A multiple regression analysis indicated that the mutant frequency increased significantly as a function of the 84F coding single nucleotide polymorphism and smoking, according to the model; mutant frequency (×10)=0.90+0.618 (84F polymorphism)+0.46 (smoking) with R=0.22. Mutation spectra analysis revealed an apparent increase, which was short of statistical significance (P=0.08), in base substitutions in cells with the 84F polymorphism. CONCLUSIONS: These new data suggest that the 84F coding single nucleotide polymorphism may alter the phenotype of the MGMT protein, resulting in suboptimal repair of O-methylguanine lesions after exposure to alkylating agents.

KW - Biomarkers

KW - Cancer

KW - DNA repair

KW - HPRT

KW - MGMT

KW - Mutation

KW - Polymorphism

KW - Smoking

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