Aromatic DNA adduct levels in coke oven workers: correlation with polymorphisms in genes GSTP1, GSTM1, GSTT1 and CYP1A1

The aim of this study was to use DNA adducts levels, detected by 32P-postlabelling, as a biomarker to assess human exposure to polycyclic aromatic hydrocarbons (PAHs) from a coke oven plant and explore the possible association between CYP1A1 MspI, GSTP1, GSTM1 and GSTT1 genotypes, and smoking status on bulky DNA adduct formation. A large amount of inter-individual variation in adduct level was observed among workers with the same job and the same smoking habits. No significant differences were observed in DNA adduct levels between the coke oven workers and control group. Smokers in the control group had significantly higher DNA adducts than the non-smokers in the same group (35.13+/-21.11 versus 11.18+/-8.00, per 10(8) nucleotides, P=0.003). In this group, the correlation between the level of DNA adducts and the cigarettes smoked was strongly significant (r=0.70, P<0.0005), but no correlation was found among the coke oven workers. Among non-smokers there was a significant difference between the control group and the coke oven workers (11.18+/-8.00 versus 24.62+/-15.20, per 10(8) nucleotides, P=0.03). These results suggests that tobacco smoke could behave as a confounding factor for evaluation of DNA adducts arising from occupational exposure. The levels of DNA adducts in smokers not occupationally exposed to PAHs is dependent on the polymorphisms CYP1A1 MspI in the 3' non-coding region (49.04+/-22.18 versus 25.85+/-15.87, per 10(8) nucleotides, P<0.05), but no effect was observed for the GST genotypes studied.     

Impact of metabolic genotypes on levels of biomarkers of genotoxic exposure

Phase I and Phase II xenobiotic-metabolising enzyme families are involved in the metabolic activation and detoxification of various classes of environmental carcinogens. Particular genetic polymorphisms of these enzymes have been shown to influence individual cancer risk. A brief overview is presented about recent research of the relationship between metabolic genotypes and internal dose, biologically effective dose and cytogenetic effects of complex and specific genotoxic exposures of human study populations, and we report our new results from two molecular epidemiological studies. We investigated the effects of multiple interactions among CYP1A1 Ile462Val, CYP1A1 MspI, CYP1B1 Leu432Val, CYP2C9 Arg144Cys, CYP2C9 Ile359Leu, NQO1 Pro189Ser, GSTM1 gene deletion and GSTP1 Ile105Val genotypes on the levels of carcinogen-DNA adducts determined by (32)P-postlabelling and PAH-DNA immunoassay in peripheral blood lymphocytes from workers occupationally exposed to polycyclic aromatic hydrocarbons in aluminium plants, and in bronchial tissue from smoking lung patients. A statistically significant positive linear correlation was observed between white blood cell aromatic DNA adduct and urinary 1-hydroxypyrene (1-OHPY) levels from potroom workers with GSTM1 null genotype (P=0.011). Our results suggest interactions between GSTM1 and GSTP1 alleles in modulation of urinary 1-OHPY levels and white blood cell DNA adduct levels in the PAH-exposed workers. Interactions between GSTM1 and GSTP1 alleles, in association with particular genotype combinations of CYPs, were also recognised in bronchial aromatic DNA adduct levels of smoking lung patients. The impact of single metabolic genotypes and their combinations on biomarkers of exposure was usually weak, if any, in both our studies and reports of the literature. The effect of special metabolic gene interactions may be better recognised if the compared groups of individuals are stratified for multiple potential modulators of the observable biomarker end-point, and/or if chemical structure-specific biomarker methods are applied.     

Biomarkers of air pollution exposure--a study of policemen in Prague

The effect of exposure to organic compounds adsorbed onto respirable air particles (<2.5microm) on DNA adducts in lymphocytes was studied in a group of non-smoking policemen (N=109, aged 35+/-0.9 years) working in the downtown area of Prague and spending >8h daily outdoors. Personal exposure to carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) adsorbed on respirable particles was monitored in each subject for 48h before biological sampling. DNA adducts were analyzed by a (32)P-postlabelling assay, and total DNA adduct levels and B[a]P-like spots were determined. Further biomarkers included cotinine levels in urine to control for exposure to tobacco smoke, plasma levels of vitamins A, E and C and polymorphisms of metabolic genotypes (GSTM1, GSTP1, GSTT1, CYP 1A1-Msp I and Ile/Val, MTHFR, MS), DNA repair genotypes (XRCC1, hOGG1 and XPD exons 6 and 23) and the p53 gene (p53 Msp I and BstU I). All the biomarkers of exposure and effect were analyzed repeatedly during a period of one year at 2-3 month intervals (January, March, June, September 2004) to cover periods with high (winter) and low (summer) levels of air pollution. The highest personal exposure to c-PAHs was found in January (8.1+/-8.8ng/m(3)), while the other three sampling periods exhibited 3-4-fold lower c-PAH exposure. The total DNA adducts were only slightly elevated in January (2.08+/-1.60) compared to March (1.66+/-0.65), June (1.96+/-1.73) and September (1.77+/-1.77). B[a]P-like DNA adducts, however, were significantly higher in January than in the March and June sampling periods (0.26+/-0.14 vs. 0.19+/-0.12 and 0.22+/-0.13, respectively; p<0.0001 and p=0.017) indicating that c-PAH exposure probably plays a crucial role in DNA adduct formation in lymphocytes. No effect of individual metabololic or DNA repair genotypes on DNA adduct levels was observed. However, the combination of two genotypes encoding enzymes metabolizing c-PAHs - CYP 1A1 and GSTM1 - was associated with the levels of total and B[a]P-like DNA adducts under conditions of increased exposure to c-PAHs. Our study suggests that DNA adducts in the lymphocytes of subjects exposed to increased c-PAH levels are an appropriate biomarker of a biologically effective dose, directly indicating whether or not the extent of exposure to these compounds is related to an increased mutagenic and carcinogenic risk.     

Polymorphisms of glutathione S-transferases M1, T1, P1 and A1 genes in the Tunisian population: an intra and interethnic comparative approach

Genetic polymorphisms in glutathione S-transferases (GSTs) genes might influence the detoxification activities of the enzymes predisposing individuals to cancer risk. Owing to the presence of these genetic variants, inter-individual and ethnic differences in GSTs detoxification capacity have been observed in various populations. Therefore, the present study was performed to determine the prevalence GSTM1 0/0, GSTT1 0/0, GSTP1 Ile(105)Val, and GSTA1 A/B polymorphisms in 154 healthy individuals from South Tunisia, and to compare them with those observed in North and Centre Tunisian populations and other ethnic groups. GSTM1 and GSTT1 polymorphisms were analyzed by a Multiplex-PCR approach, whereas GSTP1 and GSTA1 polymorphisms were examined by PCR-RFLP. The frequencies of GSTM10/0 and GSTT1 0/0 genotypes were 53.9% and 27.9%, respectively. The genotype distribution of GSTP1 was 47.4% (Ile/Ile), 40.9% (Ile/Val), and 11.7% (Val/Val). For GSTA1, the genotype distribution was 24.7% (A/A), 53.9% (A/B), and 21.4% (B/B). The combined genotypes distribution of GSTM1, GSTT1, GSTP1 and GSTA1 polymorphisms showed that thirty one of the 36 possible genotypes were present in our population; eight of them have a frequency greater than 5%. To the best of our knowledge, this is the first report of GSTs polymorphisms in South Tunisian population. Our findings demonstrate the impact of ethnicity and reveal a characteristic pattern for Tunisian population. The molecular studies in these enzymes provide basis for further epidemiological investigations in the population where these functional polymorphisms alter therapeutic response and act as susceptibility markers for various clinical conditions.     

Effect of genetic polymorphism for metabolic enzymes on the relationship between smoking dose and DNA adducts in lymphocytes

The genetic polymorphism of metabolic enzymes on the relationship between smoking dose and DNA adduct levels in lymphocytes were evaluated in 51 smokers. The genetic polymorphisms of cytochrome P4501A1 (CYP1A1) and glutathione S-transferase M1 (GSTM1) were analysed by a PCR method. Lymphocyte DNA adducts were measured by two analytical versions of a 32P-postlabelling method; nuclease P1 digested method and butanol extracted method. Mean adduct levels obtained with the nuclease P1 method (1.21 +/- 0.74 per 108 nucleotides) were higher than those obtained with the butanol extracted method (0.82 +/- 0.47, p &lt; 0.01). There was a significant correlation between adduct levels by the nuclease P1 method and those by the butanol extracted method (r = 0.49, p &lt; 0.01). A significant correlation was not found between smoking dose and DNA adduct levels obtained using both methods in lymphocytes of all subjects. When subjects were divided into two groups by CYP1A1 genotypes, significant correlations between smoking indices, such as number of cigarettes per day years or tar intake per day years, and DNA adduct levels measured by the butanol extracted method was found in heterozygous or miner homozygous for CYP1A1 exon 7 polymorphism. We could not get a significant effect of GSTM1 on the relationship between smoking dose and DNA adducts.     

Impact of genetic variations of the CYP1A1, GSTT1, and GSTM1 genes on the risk of coronary artery disease

Carcinogenic and toxic molecules produce DNA adducts that contribute to the development of atherosclerosis. Genetic polymorphisms of xenobiotic-detoxified enzymes, which control the level of DNA adducts, may affect both enzymatic activity and individual susceptibility to coronary artery disease (CAD). In this study we investigated the effects of genetic polymorphisms of the CYP1A1*2C, GSTT1, and GSTM1 enzymes on CAD risk in a Turkish population. Genotypes were determined for 132 CAD patients and 151 healthy controls by the polymerase chain reaction/restriction fragment length polymorphism method. There were no significant differences between patients and controls in terms of CYP1A1, GSTT1, and GSTM1 genotypes. Analysis of the possible interactions between the genotypes, after adjustment for the risk factors, demonstrated that individuals carrying CYP1A1 variant GSTT1 null genotypes had an 8.907-fold increased CAD risk compared to their wild status (p<0.05). We suggest that genetic polymorphisms of xenobiotic-metabolizing enzymes could play an important role in CAD. Therefore, CYP1A1 and GSTM1 polymorphisms should be considered as important parameters for the prediction of CAD.     

Benzo(a)pyrene diolepoxide adducts to albumin in workers exposed to polycyclic aromatic hydrocarbons: association with specific CYP1A1, GSTM1, GSTP1 and EHPX genotypes

We investigated whether the presence of (+)-anti-benzo(a)pyrene diolepoxide adducts to serum albumin (BPDE-SA) among workers exposed to benzo(a)pyrene (BaP) and unexposed reference controls was influenced by genetic polymorphisms of cytochrome P4501A1 (CYP1A1), microsomal epoxide hydrolase (EHPX), glutathione S-transferases M1 (GSTM1) and P1 (GSTP1), all involved in BaP metabolism. Exposed workers had significantly higher levels of adducts (0.124 ± 0.02 fmol BPTmg^?1 SA, mean ± SE) and a higher proportion of detectable adducts (40.3%) than controls (0.051 ± 0.01 fmol BPT mg^?1 SA; 16.1%) (p = 0:014 and p = 0:012). Smoking increased adduct levels only in occupationally exposed workers with the GSTM1 deletion (GSTM1 null) (p = 0:034). Smokers from the exposed group had higher adduct levels when they were CYP1A1 *1/*1 wild-type rather than heterozygous and homozygous for the variant alleles (CYP1A1 *1/*2 plus *2/*2) (p = 0:01). The dependence of BPDE-SA adduct levels and frequency on the CYP1A1 *1/*1 genotype was most pronounced in GSTM1-deficient smokers. Exposed workers with GSTM1 null/GSTP1 variant alleles had fewer detectable adducts than those with the GSTM1 null/GSTP1*A wild-type allele, supporting for the first time the recent in vitro finding that GSTP1 variants may be more effective in the detoxification of BPDE than the wild-type allele. Logistic regression analysis indicated that occupational exposure, wild-type CYP1A1*1/*1 allele and the combination of GSTM1 null genotype+EHPX genotypes associated with predicted low enzyme activity were significant predictors of BPDE-SA adducts. Though our findings should be viewed with caution because of the relatively limited size of the population analysed, the interaction between these polymorphic enzymes and BPDE-SA adducts seems to be specific for high exposure and might have an impact on the quantitative risk estimates for exposure to polycyclic aromatic hydrocarbons.     

The role of GSTM1, GSTT1, GSTP1, and OGG1 polymorphisms in type 2 diabetes mellitus risk: a case-control study in a Turkish population

The aim of the present study was to investigate the role of some polymorphisms in GSTs (GSTM1, GSTT1 and GSTP1) which are very important protective mechanisms against oxidative stress and in OGG1 gene which is important in DNA repair, against the risk of type 2 diabetes mellitus (T2DM). 127 T2DM and 127 control subjects were included in the study. DNA was extracted from whole blood. Analyses of GSTM1 and GSTT1 gene polymorphisms were performed by allele specific PCR and those of GSTP1 Ile105Val and OGG1 Ser326Cys by PCR-RFLP. Our data showed that GSTM1 null genotype frequency had a 2-6 times statistically significant increase in a patient group (OR=3.841, 95% CI=2.280-6.469, p<0.001) but no significance with GSTT1 null/positive and GSTP1 Ile105Val genotypes was observed. When T2DM patients with OGG1 Ser326Cys polymorphism were compared with patients with a wild genotype, a 2-3 times statistically significant increase has been observed (OR 1.858, 95% CI=1.099-3.141, p=0.021). The combined effect of GSTM1 null and OGG1 variant genotype frequencies has shown to be statistically significant. Similarly, the risk of T2DM was statistically increased with GSTM1 null (OR=3.841, 95% CI=2.28-6.469), GSTT1 null+GSTP1 (H+M) (OR=4.118, 95% CI=1.327-12.778) and GSTM1 null+OGG1 (H+M) (OR=3.322, 95% CI=1.898-5.816) and GSTT1 null+OGG1 (H+M) (OR=2.179, 95% CI=1.083-4.386) as compared to the control group. According to our study results, it has been observed that the combined evaluation of GSTM1-GSTT1-GSTP1 and OGG1 Ser326Cys gene polymorphisms can be used as candidate genes in the etiology of T2DM, especially in the development of T2DM.     

Polymorphisms of cytochrome P450 1A1, glutathione s-transferases M1 and T1 genes in Ouangolodougou (Northern Ivory Coast)

In this study, the frequencies of CYP1A1, GSTM1, and GSTT1 gene polymorphisms were determined in 133 healthy individuals from Ouangolodougou, a small rural town situated in the north of the Ivory Coast. As appeared in several published studies, ethnic differences in these frequencies have been found to play an important role in the metabolism of a relevant number of human carcinogens. In the studied sample, the frequencies of Ile/Ile (wild type), Ile/Val (heterozygous variant), and Val/Val (homozygous variant) CYP1A1 genotypes were 0.271, 0.692, and 0.037, respectively. Frequencies of GSTM1 and GSTT1 null genotypes were 0.361 and 0.331, respectively. No significant differences were noted between men and women. In contrast to published data for Africans, CYP1A1 *Val Allele frequency (0.383) was significantly high (p < 0.001) in this specific population. For the GSTT1 null genotype, no differences were found between the studied and other African populations, the contrary to what occurred for the GSTM1 null genotype in relation to Gambia and Egypt.     

The Association Between Polymorphic Genotypes of Glutathione S-Transferases and COPD in the Turkish Population

Although smoking is regarded as the most important causal factor in chronic obstructive pulmonary disease (COPD), only 10–20% of smokers develop symptomatic COPD, which indicates the presence of genetic predisposing factors in its pathogenesis. This study investigates the association between gene polymorphysims of glutathione S-transferases (GSTs) and COPD. Blood samples were taken from 149 patients and 150 healthy controls. Polymorphisms of GSTT1, GSTM1, and GSTP1 were genotyped using Real-Time PCR. Multivariate logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals between specific genotypes and COPD. There was no difference in the frequencies of the genotypes of GSTM1 and GSTT1 between the groups, but the GSTP1 Ile/Ile genotype was significantly higher in the patients than in the controls (61.1% vs. 38%). GSTP1 Ile/Val and Val/Val genotypes were associated with a decreased risk of COPD when compared to the Ile/Ile genotype (2.12-fold and 4-fold, respectively). Thus we suggest that the Val allele of GSTP1 may have a protective effect for development of COPD. Furthermore, when we evaluated the association between GSTP1 genes and smoking status, smokers with the GSTP1 Ile allele had an increased risk for the development of COPD. Among the combinations of the genotypes, the combination of GSTM1, GSTT1 null, and GSTP1 Val/Val was associated with the maximal increased risk (12-fold) of COPD. Thus to explain the ethiopathogenesis of COPD, investigation of a single gene family is inadequate. Based on our results and the previous data, further studies should be focused on the GSTP1 gene and the interactions with other genes such as polymorphisms of N-acetyltransferases, GSTM1 and GSTT1, microsomal epoxide hydrolase, and allelic variants of cytochrome P450.     

Associations between smoking, GST genotypes and N7-methylguanine levels in DNA extracted from bronchial lavage cells

N7-Methylguanine (N7-MeG) DNA adducts are markers of human exposure to methylating agents including tobacco-specific nitrosamines (TSNAs). Repair of this adduct is poor, so levels in lung tissue should reflect variation in both intensity of exposure and in metabolism. N7-MeG adducts in lung DNA from bronchial lavage samples were measured to determine whether levels were higher in smokers than non-smokers, and if levels were modified by genetic variation in carcinogen-metabolising enzymes. Adducts were detected in 38 out of 44 DNA samples by 32P post-labelling of the N7-methyldeoxyguanosine-3'-monophosphate (N7-MedGp) isolated from DNA digests by two-stage HPLC. N7-MeG adduct levels were higher in smokers than in never smokers ((9.99 +/-20.3)x10(-7) versus (0.58+/-0.50)x10(-7) N7-MedGp/deoxyguanosine-3'-monophosphate (dGp); P=0.02) and intermediate in ex-smokers ((5.59+/-15.6)x10(-7) N7-MedGp/dGp). Adduct levels tended to be higher in individuals with GSTM1 null, GSTT1 null or GSTP1 ile/ile genotypes. When genotypes were combined, N7-MedGp levels among GSTM1 null/GSTT1 null individuals (n=6) were higher than among those having at least one wild-type allele of these two genes ((26.1+/-38.0)x10(-7) versus (2.73+/-4.07)x10(-7) N7-MedGp/dGp), although the results were not statistically significant (P=0.13). Adduct levels were highest in individuals with three unfavourable genotypes (GSTM1 null/GSTT1 null and GSTP1 ile/ile) compared with others ((74.5+/-13.1)x10(-7) versus (2.64+/-3.89)x10(-7) N7-MedGp/dGp, P=0.02). N7-MeG adduct levels in DNA isolated from lung tissue thus reflect exposure to cigarette smoke, and genetic variation in carcinogen-metabolising enzymes may modify these levels.     

Genetic polymorphism of lysyl oxidase,glutathione S-transferase M1, glutathione-S-transferase T1, and glutathione S-transferase P1 genes as risk factors for lung cancer in Egyptian patients

Lung cancer is a lethal malignancy and is affected by genetic polymorphisms that contribute to an individual’s susceptibility to developing the disease. Several studies on lung cancer showed conflicting results. The aim of this study is to investigate whether individual or combined modifying effects of LOX G/A, GSTM1 active/null, GSTT1 active/null and GSTP1 Ile/Val polymorphisms are related to the risk of lung cancer in relation to smoking in the Egyptian population. This study is a hospital-based case control study that included 200 patients and 200 control subjects. Genotyping of the 4 studied genes was determined by Multiplex PCR for GSTM1 and GSTT1 and Taq man SNP assay for GSTP1 and LOX genes. The LOX G/A and GSTP1 Ile/Val in both homozygous and heterozygous variants, and the GSTM1 and GSTT1 null genotype showed significant association with lung cancer. Combination between gene polymorphism and smoking increased the risk of developing cancer by 2.7 fold in the LOX GA+AA variant, 1.9 fold in the GSTM1 null variant, 4.8 fold in the GSTT1 null variant and 4.3 fold in the GSTP1 Ile/Val+Val/Val variant. The genetic combination (LOX GA+AA/GSTT1 active, LOX GG/GSTT1 null, LOX GA+AA/GSTT1 null, LOX GA+AA/GSTP1 Ile/Ile, LOX GG/GSTP1 Ile/Val+Val/Val and LOX GA+AA/GSTP1 Ile/Val+Val/Val) led to a higher lung cancer risk, compared to the reference group. The LOX GA/AA, GSTM1 null, GSTT1 null and GSTP1 Ile/Val, Val/Val genotypes contributed to increased lung cancer susceptibility. To the best of our knowledge, this is the first study of LOX genotyping in the Egyptian population. The combination of genotypes increased the risk of cancer, indicating the importance of gene–gene interaction and giving a targeted preventive approach.

     

Glutathione S-Transferase M1, T1, P1 Genotypes and Risk for Development of Colorectal Cancer

The glutathione S-transferase (GST) supergene family is an important part of cellular enzyme defense against endogenous and exogenous chemicals, many of which have carcinogenic potential. The present investigation was conducted to detect a possible association between polymorphisms at the GSTM1, GSTT1, and GSTP1 genes and the interaction with cigarette smoking and colorectal cancer incidence. We examined 181 patients with colorectal cancer and 204 controls. DNA was extracted from whole blood, and the GSTM1, GSTT1, and GSTP1 polymorphisms were determined using a real-time polymerase chain reaction and fluorescence resonance energy transfer with a Light-Cycler instrument. Associations between specific genotypes and the development of colorectal cancer were examined by use of logistic regression analysis to calculate odds ratios (OR) and 95% confidence intervals (CI). The GSTM1 polymorphism was associated with an increased risk of developing colorectal cancer (OR = 1.62, 95% CI: 1.06–2.46). Also the risk of colorectal cancer associated with the GSTT1 null genotype was 1.64 (95% CI: 1.10–2.59). Statistically no differences were found between patients with colorectal cancer and control groups for the GSTP1 Ile/Ile, Ile/Val and Val/Val genotypes. In addition, the frequencies of the GSTM1 and GSTT1 deletion genotypes differed significantly between the cases and controls for current smokers; the GSTT1 null genotype especially is associated with a greater risk of colorectal cancer (OR = 2.44, 95% CI: 1.24–4.81). The GSTM1 and GSTT1 deletions were associated with an increased risk of developing a transverse or rectal tumor (OR = 1.86, 95% CI: 1.15–3.00; OR = 1.70, 95% CI: 1.02–2.84; respectively). The glutathione S-transferase polymorphisms were not associated with risk in patients stratified by age. The risk of colorectal cancer increased as putative high-risk genotypes increased for the combined genotypes of GSTM1 null, GSTT1 null, and either GSTP1 valine heterozygosity or GSTP1 valine homozygosity (OR = 2.69, 95% CI: 1.02–7.11). In conclusion, the results obtained in this study clearly suggest that those susceptibility factors related to different GST polymorphic enzymes are predisposing for colorectal cancer.     

Effects of metabolic genotypes on intermediary biomarkers in subjects exposed to PAHS: results from the EXPAH study

Data from the EXPAH project on PAH exposure and intermediary biomarkers were analyzed with respect to individual genotypes at seven metabolic gene loci. The GSTM1 null allele was associated with significantly higher levels of two biomarkers, malondialdehyde-2′-deoxyguanosine and benzo[a]pyrene DNA adducts in the total population from three Central and Eastern European countries. The CYP1B1 Leu/Val variant demonstrated effects on both markers of oxidative DNA damage in opposite directions, producing a higher level of M₁dG with a trend from wild type (Leu/Leu) to heterozygotes to homozygous (Val/Val) variants, whereas the effects of these variants were reversed for 8-oxodG. Cluster Analysis was used to group composite genotypes in order to determine if combined genotypes of multiple loci could explain some of the variation seen with the biomarkers, expressed per unit of exposure, referred to as a sensitivity index. This analysis revealed two closely related genotypes each involving four of the loci (GSTM1*0/*0, CYP1A1*1*1, CYP1B1*1/*2, GSTP1*1/*1 and GSTT1*0/*0, CYP1A1*1*1, CYP1B1*1/*2, GSTP1*1/*1.) that conferred significant resistance to the DNA damaging effects of benzo[a]pyrene, measured as the level of a benzo[a]pyrene-like adduct per unit of benzo[a]pyrene exposed.     

Lymphocytes,DNA adducts and genetic polymorphism for metabolic enzymes in low dose cigarette smokers

The aim of this study was to investigate the relationship between genetic polymorphism of metabolic enzymes and DNA adduct levels in lymphocytes of low dose cigarette smokers (less than 20 cigarettes per day). We previously reported the effects of cytochrome P4501A1 (CYP1A1) and glutathione S-transferase M1 (GSTM1) on lymphocyte DNA adducts. This time we considered not only CYP1A1 and GSTM1 but also cytochrome P4502E1 (CYP2E1) and glutathione S-transferase T1 (GSTT1). DNA adducts in lymphocytes obtained from low dose cigarette smokers (n = 41) and nonsmokers (n = 56) were measured by the 32P-postlabelling method. The adduct levels were compared regarding smoking status and polymorphic genotypes of these four enzymes. The mean SD of DNA adduct levels in all low dose cigarette smokers and non-smokers was 1 05 0 83 per 108 nucleotidesand 0 85 0 35 per 108 nucleotides, respectively. In low dose cigarette smokers, adduct levels were higher in the rare homozygous (MM) for CYP1A1-exon 7 polymorphism compared with the other types such as common homozygous (WW) and heterozygous (WM). CYP1A1-WM, MM in combination with GSTM1 null showed highest adduct levelamong low smokers. The low smokers with rare homozygous for CYP2E1 Dra1 polymorphism tended to have lower adduct levels than wild types. Low dose cigarette smokers with combined GSTM1 null and T1 null had a higher tendency for adduct levels than others. However none of the differences reached statistical significance.     

Polymorphisms of the CYP1A1 and GSTM1 genes in relation to individual susceptibility to lung carcinoma in Chinese population.

Cytochrome P450 1A1 (CYP1A1) and glutathione S-transferase M1 (GSTM1) metabolize tobacco-related carcinogens. To investigate the prevalence of CYP1A1 and GSTM1, and their association with increased risk of lung carcinoma in Chinese, allele-specific PCR and multiplex PCR technique were employed to identify the genotypes of CYP1A1 and GSTM1 in a case-control study of 106 lung carcinoma patients with histopathological diagnosis and 106 matched controls free of malignancy in Jiangsu Province, China. Logistic regression analysis was performed to calculate the odds ratio (OR) and 95% confidence intervals (CI). The results showed that individuals with GSTM1 null, and the combined GSTM1 null/CYP1A1 Ile/Val or GSTM1 null/CYP1A1 Val/Val had an elevated risk of lung carcinoma, with the OR, 1.92 (P=0.02; CI, 1.07-3.46), 3.27 (P=0.01; CI, 1.23-8.84) and 9.33 (P=0.04; CI, 1.01-217.42), respectively. Light smokers (<30 pack-years) carrying GSTM1 null genotype were shown to have the increased risk to lung carcinoma (OR=3.47; CI, 1.13-7.57). Our study suggested that the null GSTM1 genotype, independently or in combined with at least one Val allele of CYP1A1, might affect the genetic susceptibility for lung carcinoma in Chinese population.     

Impact of glutathione-S-transferase gene polymorphisms on enzyme activity, lung function and bronchial asthma susceptibility in Egyptian children

Background

Asthma is a complex multifactorial disease with an obvious genetic predisposition. Polymorphisms of the glutathione-S-transferase (GST) genes are known risk factors for some environmentally-related diseases. The aim of the present study was to investigate the role of polymorphisms in the GSTT1, GSTM1 and GSTP1 genes and asthma susceptibility in Egyptian children, and to analyze their effect on GST activity and lung function.

Methods

GSTT1 and GSTM1 gene polymorphism was genotyped using the multiplex polymerase chain reaction (PCR) and GSTP1 ILe105Val polymorphism was determined using PCR-restriction fragment length polymorphism (PCR-RFLP) in 168 healthy and 126 asthmatic children (82 atopic and 44 nonatopic). Also GST enzyme activity and lung function were evaluated.

Results

Asthmatic children had a significant higher prevalence of the GSTM1 null (P = 0.003) and significant lower prevalence of GSTP1 Val/Val genotypes (P = 0.02) than control group. Lung function was significantly decreased in GSTM1 null genotype and GSTP1 Ile/Ile genotype. GSTP1 Val/Val genotypes and GSTM1 null genotype had a significant decrease in plasma GST activity.

Conclusions

GST genes polymorphisms may play an important role in pathogenesis and susceptibility to asthma in children.     

Smoking-reIated DNA adducts and genetic polymorphism for metabolic enzymes in human lymphocytes

Smoking-related aromatic DNA adducts in lymphocytes were measured from smokers (n = 76), ex-smokers (n = 25) and non-smokers (n = 56) by the ³²P-postlabelling method, to clarify whether a genetic polymorphism for metabolic enzymes could explain the inter-individual variation of DNA adduct levels. Adduct levels were compared with respect to smoking status and polymorphic genotypes of cytochrome P4501A1 (CYP1A1) and glutathione S-transferase M1 (GTSM1). The mean adduct level (1.24 per 10⁸ nucleotides) in smokers was significantly higher than that (0.85 per 10⁸) in non-smokers. Although we expected higher adduct levels in the CYP1A1 variant or GSTM1 null subjects, the adduct level in 'GSN1 nulls' was significantly lower than that in 'GSTM1 presents' among smokers. DNA adduct levels had significant positive correlations with smoking indices such as number of cigarettes or smoking years in all subjects. In smokers only, however, no correlation was found, because there were negative correlations between adduct levels and smoking dose in GSTM1 null genotypes. CYP1A1 genotypes had no effects on adduct levels.