Copy Number Variants of GSTM1 and GSTT1 in Relation to Lung Cancer Risk in a Prospective Cohort Study

Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA.
Annals of epidemiology (Impact Factor: 2). 05/2009; 19(8):546-52. DOI: 10.1016/j.annepidem.2009.03.003
Source: PubMed


Previous studies did not discriminate wild-type from hemizygous genotypes of GSTM1 and GSTT1. In this study, we investigated wild-type, hemizygous deletion, and homozygous deletion genotypes of GSTM1 and GSTT1 and lung cancer risk.
We conducted a nested case-control study of 143 primary incident lung cancer cases matched to 447 cancer-free controls. Genotyping was carried out using a real-time polymerase chain reaction (PCR)-based assay. Conditional logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI).
Compared to GSTM1 wild-type carriers, the relative odds of lung cancer increased from 1.49 (95% CI=0.66-3.40) to 1.80 (95% CI=0.81-4.02) for the hemizygous and homozygous deletion genotypes, respectively (p-trend=0.13). The strongest associations were seen among those who smoked less than one pack per day and had greater than or equal to one deletion variant of GSTM1 (OR=3.25; 95% CI=0.93-11.34; p-trend=0.07) whereas the reverse was observed for smokers who smoked greater than or equal to one pack per day (OR=0.80; 95% CI=0.24-2.67; p-interaction=0.08). No clear associations were observed for GSTT1 genotypes.
Risk of lung cancer increased as the number of deletion variants increased for GSTM1, although the associations were nonsignificant. Discriminating between the wild-type, hemizygous, and homozygous deletion GSTM1 genotypes permitted a more precise characterization of the associations between GSTM1 deletion variants and lung cancer.

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    • "These methods were primarily based on the fact that the two genes are flanked by highly homologous regions. Recent studies have used Taqman based real-time PCR assays to discriminate between the wild-type, hemizygous deletion, and homozygous deletion of the GSTM1 and GSTT1 genes1314. In our previous report on association of GST polymorphisms, comparing the null genotype (-/-) with combined non-null genotype (+/- and +/+) using traditional multiplex PCR-gel electrophoresis method in high risk north-east Indian population, we showed a significant protective effect of GSTM1 and GSTT1 null genotypes in lung cancer15. "
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    ABSTRACT: Background & objectives: Genetic polymorphisms in glutathione-S-transferase genes (GSTM1 and GSTT1) have been studied intensively for their potential role in lung cancer susceptibility. However, most of the studies on association between the polymorphisms and lung cancer do not distinguish between genotypes with one or two copies of the genes. The present study investigates the gene dosage effects of GSTT1 and GSTM1 copy number and their environmental interactions to examine the association of lung cancer risk with trimodular genotypes of the GSTs in a high-risk population from north-east India. Methods: A total of 154 lung cancer cases and 154 age and sex matched controls from the high risk region of north-east India were analyzed by multiplex real-time PCR to determine the trimodal genotypes (+/+, +/- and -/-) in both the genes (GSTM1 and GSTT1). Results: No significant association and gene dosage effect of GSTM1 gene copy number with lung cancer risk (Ptrend=0.13) were found. However, absence of GSTT1 conferred 68 per cent (OR=0.32;95%CI=0.15-0.71; P=0.005) reduced risk compared to the two copy number of the gene. There was evidence of gene dosage effect of GSTT1 gene (Ptrend=0.006). Tobacco smoking was a major environmental risk factor to lung cancer (OR=3.03;95%CI=1.73-5.31; P<0.001). However, its interaction with null genotype of GSTT1 conferred significant reduced risk to lung cancer (OR=0.30;95%CI=0.10-0.91; P=0.03). Further in only tobacco smokers, null genotype was associated with increased reduced risk [0.03(0.001-0.78)0.03; Ptrend=0.006]. No effect modification of GSTM1 was observed with lung cancer risk by environmental risk factors. Interpretation & conclusions: The results suggest that absence of GSTT1 null genotype may be associated with a reduced risk of lung cancer and the effect remains unchanged after interaction with smoking.
    The Indian Journal of Medical Research 05/2014; 139(5):720-9. · 1.40 Impact Factor
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    • "The absence of GSTM1/GSTT1 activity is the result of homozygosity for an inherited deletion of these genes, termed the null genotype (Hayes and Pulford, 1995), which combined with cigarette smoking has been implicated as a risk factor for a wide range of tobacco-related diseases, including susceptibility to coronary heart disease (Li et al., 2000; Wang et al., 2008; Wang et al., 2010), cerebrovascular diseases (Um et al., 2006), lung cancer (Schneider et al., 2004; Lam et al., 2009), and COPD (Xue et al., 2012). In contrast, another study did not find an association between GSTM1/GSTT1 null genotype and risk of ischemic heart disease (Norskov et al., 2011). "
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    ABSTRACT: Nicotine dependence is associated with an increased risk of mood and anxiety disorders and suicide. The primary hypothesis of this study was to identify whether the polymorphisms of two glutathione-S-transferase enzymes (GSTM1 and GSTT1 genes) predict an increased risk of mood and anxiety disorders in smokers with nicotine dependence. Smokers were recruited at the Centre of Treatment for Smokers. The instruments were a sociodemographic questionnaire, Fagerström Test for Nicotine Dependence, diagnoses of mood disorder and nicotine dependence according to DSM-IV (SCID-IV), and the Alcohol, Smoking and Substance Involvement Screening Test. Anxiety disorder was assessed based on the treatment report. Laboratory assessment included glutathione-S-transferases M1 (GSTM1) and T1 (GSTT1), which were detected by a multiplex-PCR protocol. Compared with individuals who had both GSTM1 and GSTT1 genes, a higher frequency of at least one deletion of the GSTM1 and GSTT1 genes was identified in anxious smokers [odds ratio (OR)=2.21, 95% confidence interval (CI)=1.05-4.65, P=0.034], but there was no association with bipolar and unipolar depression (P=0.943). Compared with nonanxious smokers, anxious smokers had a greater risk for mood disorders (OR=4.67; 95% CI=2.24-9.92, P<0.001), lung disease (OR=6.78, 95% CI=1.95-23.58, P<0.003), and suicide attempts (OR=17.01, 95% CI=2.23-129.91, P<0.006). This study suggests that at least one deletion of the GSTM1 and GSTT1 genes represents a risk factor for anxious smokers. These two genes may modify the capacity for the detoxification potential against oxidative stress.
    Psychiatric genetics 03/2014; 24(3). DOI:10.1097/YPG.0000000000000023 · 1.94 Impact Factor
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    • "In this study, we found a potential dose–response effect of GSTM1 on the relationship between FEF25-75 and ozone exposure. This result is consistent with the dose–response relationship between GSTM1 and the risk of lung cancer on smokers [22]. "
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    ABSTRACT: Background We previously reported that asthmatic children with GSTM1 null genotype may be more susceptible to the acute effect of ozone on the small airways and might benefit from antioxidant supplementation. This study aims to assess the acute effect of ozone on lung function (FEF25-75) in asthmatic children according to dietary intake of vitamin C and the number of putative risk alleles in three antioxidant genes: GSTM1, GSTP1 (rs1695), and NQO1 (rs1800566). Methods 257 asthmatic children from two cohort studies conducted in Mexico City were included. Stratified linear mixed models with random intercepts and random slopes on ozone were used. Potential confounding by ethnicity was assessed. Analyses were conducted under single gene and genotype score approaches. Results The change in FEF25-75 per interquartile range (60 ppb) of ozone in persistent asthmatic children with low vitamin C intake and GSTM1 null was −91.2 ml/s (p = 0.06). Persistent asthmatic children with 4 to 6 risk alleles and low vitamin C intake showed an average decrement in FEF25-75 of 97.2 ml/s per 60 ppb of ozone (p = 0.03). In contrast in children with 1 to 3 risk alleles, acute effects of ozone on FEF25-75 did not differ by vitamin C intake. Conclusions Our results provide further evidence that asthmatic children predicted to have compromised antioxidant defense by virtue of genetic susceptibility combined with deficient antioxidant intake may be at increased risk of adverse effects of ozone on pulmonary function.
    Respiratory research 02/2013; 14(1):14. DOI:10.1186/1465-9921-14-14 · 3.09 Impact Factor
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