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.     

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.     

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.     

Genotoxic effects of doxorubicin in cultured human lymphocytes with different glutathione S-transferase genotypes

Doxorubicin (Dox) is a widely used drug in oncology with a broad spectrum of interactions with various cellular components; therefore, it is likely to act through different mechanisms. In clinical practice there is inter-individual variability in cytotoxic drug response and in the occurrence of adverse reactions. Glutathione S-transferases (GSTM1, GSTT1 and GSTP1) are thought to be involved in the detoxification of endogenous and exogenous genotoxicants. The aim of this work is the assessment of a possible influence of polymorphisms in GSTs on the levels of genetic damage induced in vitro by Dox in cultured human lymphocytes. For this purpose, whole blood cultures from individuals with different genotypes for GSTM1, GSTT1 and GSTP1 were exposed to Dox and the cytokinesis-blocked micronucleus (CBMN) assay was used as the endpoint for chromosomal damage in the lymphocytes. Genotyping of GSTM1 and GSTT1 was carried out by multiplex PCR and the GSTP1-Ile105Val polymorphism was determined by PCR/RFLP. The total number of micronuclei present in 1000 binucleated cells and the frequency of micronucleated binucleated lymphocytes in the different individuals were analyzed considering the GSTM1, GSTT1 and GSTP1 genotypes. The results obtained suggest that GSTM1 and GSTT1 deletion polymorphisms do not modify significantly the genotoxic potential of Dox. However, the GSTP1 Ile105Val polymorphism was associated with an increase of micronucleated binucleated cells induced by Dox. Lymphocytes from homozygous individuals for the variant form (Val/Val) presented a significant increase in micronucleated binucleated cells (approximately 1.5-fold; p<0.05) when compared with individuals with at least one wild-type allele. These results suggest a possible role for GSTP1 on the modulation of the genotoxicity induced by Dox, which may be considered in cancer therapy.     

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.     

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.     

Glutathione S-transferase M1, T1 and P1 genetic polymorphisms, cigarette smoking and gastric cancer risk

Glutathione S-transferases (GSTs) belong to a superfamily of detoxification enzymes that provide critical defences against a large variety of chemical carcinogens and environmental toxicants. GSTs are present in most epithelial tissues of the human gastrointestinal tract. We investigated associations between genetic variability in specific GST genes (GSTM1, GSTT1 and GSTP1), the interaction with cigarette smoking and susceptibility to gastric cancer. The GSTM1, GSTT1 and GSTP1 polymorphisms were determined using real-time polymerase chain reaction (PCR) and fluorescence resonance energy transfer with Light Cycler Instrument. The study included 70 patients with gastric cancer and 204 controls. Associations between specific genotypes and the development of gastric cancer were examined by use of logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI). The GSTM1 homozygous null genotype was associated with an increased risk of developing gastric cancer (OR = 1.73; 95% CI = 1.10-3.04). GSTT1 homozygous null genotype and GSTP1 genotypes were not associated with the risk of gastric cancer. Also there was no difference between cases and controls in the frequency of val-105 and ile-105 alleles (p = 0.07). After grouping according to smoking status, GSTM1 null genotype was associated with an increased gastric cancer risk for smokers (OR = 2.15; 95% CI, 1.02-4.52). There were no significant differences in the distributions of any of the other GST gene combinations. Our findings suggest that the GSTM1 null genotype may be associated with an increased susceptibility to gastric cancer.     

Frequencies of GSTM1, GSTT1, and GSTP1 polymorphisms in a Brazilian population

The glutathione S-transferase (GST) family of enzymes has a vital role in phase II of biotransformation of environmental carcinogens, pollutants, drugs and other xenobiotics. GSTs are polymorphic, with the type and frequency of polymorphism being ethnic dependent. Polymorphisms in GST genes have been shown to be associated with susceptibility to disease and disease outcome. We determined the frequencies of GSTM1, GSTT1 and GSTP1 polymorphisms in 591 volunteers who had been residents of Rio de Janeiro for at least six months. Blood was collected and DNA extracted by proteinase K/SDS digestion. Information about social habits and health problems was also recorded. GSTM1 and GSTT1 polymorphisms were analyzed by a PCR-Multiplex procedure, whereas GSTP1 polymorphism was analyzed by PCR-RFLP. We found that 42.1% (48.9% of whites and 34.2% of non-whites) of the individuals had the GSTM1 null genotype, whereas 25.4% (25.1% of whites and 25.7% of non-whites) had the GSTT1 null genotype. The genotypic distribution of GSTP1 was 49.7% I/I, 38.1% I/V, and 12.2% V/V, whereas the allelic frequencies were 0.69 for the Ile allele, and 0.31 for the Val allele. The frequencies of GST polymorphisms in this Brazilian population were found to be different from those observed in other populations, particularly of other South American countries.     

Association of genetic polymorphisms of glutathione-S-transferase genes (GSTT1, GSTM1, and GSTP1) and susceptibility to nonalcoholic fatty liver disease in Zahedan, Southeast Iran

Oxidative damage is thought to play a pivotal role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Glutathione-S-transferases (GSTs) are involved in cell protection against oxidative stress. We examined whether GSTM1, GSTT1, and GSTP1 polymorphisms are associated with NAFLD in a sample of the Iranian population. The current case-control study included 83 patients with NAFLD and 93 healthy subjects. The GSTM1 and GSTT1 polymorphisms were analyzed by multiplex polymerase chain reaction (PCR). The GSTP1 polymorphism was detected by tetra amplification refractory mutation system-PCR assay. The GSTM1-null genotype was significantly associated with the development of NAFLD (odds ratios [OR]=2.171, 95% confidence intervals [CI]=1.188-3.970, p=0.015). The GSTP1 Val allele was shown to be a risk factor for NAFLD (OR=1.739, 95% CI=1.089-2.777, p=0.024). The GSTT1 polymorphism was not significantly different between control and patient groups (p=0.221). This study showed that GSTM1 and GSTP1, but not GSTT1, genetic polymorphisms are associated with NAFLD in a sample of the Iranian population, and may be used to determine the risk of development of NAFLD.     

Relationship between GSTM1 and GSTT1 polymorphisms and schizophrenia: A case–control study in a Tunisian population

There is substantial evidence found in the literature that supports the fact that the presence of oxidative stress may play an important role in the pathophysiology of schizophrenia. The glutathione S-transferases (GSTs) forms one of the major detoxifying groups of enzymes responsible for eliminating products of oxidative stress. Interindividual differences observed in the metabolism of xenobiotics have been attributed to the genetic polymorphism of genes coding for enzymes involved in detoxification. Thus, in this study we investigated the association of glutathione S-transferase Mu-1 (GSTM1) and glutathione S-transferase theta-1 (GSTT1) gene deletion polymorphisms and schizophrenia in a Tunisian population. A case–control study including 138 schizophrenic patients and 123 healthy controls was enrolled. The GSTM1 and GSTT1 polymorphisms were analyzed by multiplex polymerase chain reaction (PCR). No association was found between the GSTM1 genotype and schizophrenia, whereas the prevalence of the GSTT1 active genotype was significantly higher in the schizophrenic patients (57.2%) than in the controls (45.5%) with (OR = 0.6, IC 0.37–0.99, p = 0.039). Thus, we noted a significant association between schizophrenia and GSTT1 active genotype. Furthermore, the combination of the GSTM1 and GSTT1 null genotypes showed a non-significant trend to an increased risk of schizophrenia. The present finding indicated that GSTT1 seems to be a candidate gene for susceptibility to schizophrenia in at least Tunisian population.     

Potential risk modifications of GSTT1, GSTM1 and GSTP1 (glutathione-S-transferases) variants and their association to CAD in patients with type-2 diabetes

Background

Type-2 diabetes mellitus (T2DM) is a major risk factor for coronary artery disease (CAD) resulting in high morbidity and mortality. Glutathione S-transferases (GSTM1, GSTT1 and GSTP1) are known for their broad range of detoxification and in the metabolism of xenobiotics. Recent studies revealed the relationship of GSTs variants with T2DM and CAD. In this case-control study we ascertained the association of GSTs variants in association with the development of CAD in patients with T2DM.

Methods

From the Southern part of India, we enrolled 222 T2DM patients, 290 T2DM patients with CAD and 270 healthy controls matched for age, sex and origin. Serum lipid profiles were measured and DNA was extracted from the blood samples. Multiplex PCR for GSTM1/T1 (null polymorphism) and PCR-RFLP for GSTP1 (105 A > G), were performed for genotyping of study participants. Gene frequency and lipid profiles were statistically analyzed for disease association.

Results

Regression analysis showed that, GSTM1-null genotype is associated with a 2-fold increase (OR = 2.925; 95% CI = 2.078–4.119; P < 0.0001) and GSTT1-null genotype is associated with a 3-fold increase (OR = 3.114; 95% CI = 2.176–4.456; P < 0.0001) to T2DM development. Ile/Val and Val/Val genotypes of GSTP1 also showed a significant risk for T2DM (OR = 1.423, CI = 1.041–1.946; P = 0.027 and OR = 1.829, CI = 1.064–3.142; P = 0.029). Increased odds ratio showed that GSTT1-null genotype had a moderately higher occurrence in T2DM–CAD patients (OR = 1.918, 95% CI = 1.144–3.214; P = 0.014) than T2DM patients without CAD. The level of HDL has significantly decreased in GSTT1-present than in GSTT1-null genotype (43.50 ± 4.10 vs. 45.20 ± 3.90; P = 0.004) when compared with control and T2DM patients. However, LDL level showed a significant increase in GSTT1-null than GSTT1-present genotype (108.70 ± 16.90 vs. 102.20 ± 12.60; P = 0.005). Although the GSTM1-null polymorphism showed no correlation with lipid profiles among T2DM and T2DM with CAD patients, GSTT1-null polymorphism attained a statistical significance for the level of LDL (127 ± 28.20 vs. 134 ± 29.10; P = 0.039) and triglycerides in T2DM with CAD patients (182.10 ± 21.10 vs. 191.20 ± 24.10; P = 0.018).

Conclusion

Our work concludes that GSTM1, GSTT1 and GSTP1 variants might contribute to the development of T2DM and GSTT1 variant alone is involved in the development of T2DM associated CAD complications in the South Indian population.     

Influence of glutathione S-transferase polymorphisms (GSTT1, GSTM1, GSTP1) on type-2 diabetes mellitus (T2D) risk in an endogamous population from north India

Glutathione S-transferases (GSTs) belong to a group of multigene and multifunctional detoxification enzymes, which defend cells against a wide variety of toxic insults and oxidative stress. Oxidative stress leads to cellular dysfunction which contributes to the pathophysiology of diseases such as cancer, atherosclerosis, and diabetes mellitus. It is important to assess whether the glutathione S-Transferase (GSTT1, GSTM1 and GSTP1) genotypes are associated with type 2 diabetes mellitus as deletion polymorphisms have an impaired capability to counteract the oxidative stress which is a feature of diabetes. GSTT1, GSTM1 and GSTP1 gene polymorphisms were analysed in 321 patients and 309 healthy controls from an endogamous population from north India. An association analysis was carried out at two levels (a) individual genes and (b) their double and triple combinations. The proportion of GSTT1 and GSTM1 null genotypes was higher in diabetics compared to controls (GSTT1 30.8 vs. 21.0 %; GSTM1 49.5 vs. 27.2 %). The frequency of the null genotype at both loci was higher in diabetics (19.6 vs. 7.8 %) leading to an odds ratio of 2.90 (CI 1.76–4.78, P < 0.0001). At GSTP1locus, patients had a higher frequency of the V/V genotype (15.6 vs. 7.5 %) and significant susceptible odds ratio (2.56, CI 1.47–4.48, P < 0.001). A combination of null genotypes at GSTT1 and GSTM1 loci and V/V genotype of GSTP1 locus showed highest odds ratio (9.64, CI 1.53–60.63, P < 0.01). Overall this study highlights that GST genes may play an important role in the pathogenesis of type 2 diabetes. The risk is higher in individuals carrying more than one susceptible genotype at these loci. The potential role of GST polymorphisms as markers of susceptibility to type 2 diabetes needs further investigations in a larger number of patients and populations.     

Genetic polymorphism of the glutathione-S-transferase P1 gene (GSTP1) and susceptibility to prostate cancer in the Kashmiri population

Glutathione-S-transferase P1 (GSTP1) is a critical enzyme of the phase II detoxification pathway. One of the common functional polymorphisms of GSTP1 is A→G at nucleotide 313, which results in an amino acid substitution (Ile105Val) at the substrate binding site of GSTP1 and reduces catalytic activity of GSTP1. To investigate the GSTP1 Ile105Val genotype frequency in prostate cancer cases in the Kashmiri population, we designed a case-control study, in which 50 prostate cancer cases and 45 benign prostate hyperplasia cases were studied for GSTP1 Ile105Val polymorphism, compared to 80 controls taken from the general population, employing the PCR-RFLP technique. We found the frequency of the three different genotypes of GSTP1 Ile105Val in our ethnic Kashmir population, i.e., Ile/Ile, Ile/Val and Val/Val, to be 52.4, 33.3 and 14.3% among prostate cancer cases, 48.5, 37.5 and 14% among benign prostate hyperplasia cases and 73.8, 21.3 and 5% in the control population, respectively. There was a significant association between the GSTP1 Ile/Val genotype and the advanced age group among the cases. We conclude that GSTP1 Ile/Val polymorphism is involved in the risk of prostate cancer development in our population.     

The effect of the genetic polymorphisms of CYP1A1,CYP2D6, GSTM1 and GSTP1 on aromatic DNA adduct levels in the population of healthy women

Aromatic DNA adduct levels and polymorphisms of two phase I enzymes - CYP1A1 and CYP2D6 and two phase II enzymes - GSTM1 and GSTP1 were analyzed in a group of 133 nonsmoking healthy women 35-45 years old and holding jobs not connected with the exposure to the combustion products of organic matter. They were office workers from the south and north-eastern parts of Poland. Blood samples were collected in winter and in summer. Aromatic DNA adduct levels were measured in all winter and summer samples. The frequencies of CYP1A1, CYP2D6, GSTM1 and GSTP1 polymorphisms in samples from the studied women did not show any differences when compared with other Caucasian populations and the Polish male population studied previously. The differences in the levels of DNA adducts among the carriers of different genotypes were statistically non-significant. Analysis of combined genotypes selected the groups of volunteers with the highest and the lowest DNA adduct levels. The highest levels of DNA adducts were observed in the carriers of GSTM1(null)/CYP1A1Ile/Val (8.00+/-13.00 adducts/10(8) nucleotides in summer samples) and GSTP1-AA/CYP1A1Ile/Val genotypes (7.00+/-4.32 in winter and 7.30+/-7. 27/10(8) nucleotides in summer). The lowest levels of DNA adducts (3. 00+/-2.30 in winter and 2.00+/-3.16/10(8) nucleotides in summer) were found in the carriers of the genotype GSTP1-AG+GG/CYP1A1Ile/Val. The levels of DNA adducts in these groups were determined by the polymorphisms of GSTM1 and GSTP1 phase II detoxifying enzymes.     

Genetic polymorphisms in GSTM1, GSTT1, GSTP1, GSTM3 and the susceptibility to gallbladder cancer in North India

Abstract

The glutathione S-transferase (GSTs) are polymorphic supergene family of detoxification enzymes that are involved in the metabolism of numerous potential carcinogens. Several allelic variants of polymorphic GSTs show impaired enzyme activity and are suspected to increase the susceptibility to various cancers. To find out the association of GST variants with risk of gallbladder cancer, the distribution of polymorphisms in the GST family of genes (GSTT1, GSTM1, GSTP1, and GSTM3) were studied in 106 cancer patients and 201 healthy controls. Genotypes were analysed by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP). The frequencies of GSTM1 null and GSTM3*BB genotypes did not differ between patients and controls. The overall frequency of GSTT1 null was lower in cases as compared with controls (p=0.003, Odds ratio (OR)?=?0.2, 95% confidence interval (CI), 0.1–0.6). After sex stratification, the GSTT1 null frequency was reduced only in female patients (p=0.008, OR?=?0.2, 95% CI?=?0.1–0.6). However, the GSTP1, ile/val genotype and the val allele were significantly higher in cases than controls (p=0.013, OR?=?1.9, 95% CI?=?1.1–3.1; p=0.027, OR?=?1.5, 95% CI?=?1.0–2.1), respectively. To study gene–gene interactions, a combined risk of gallbladder cancer due to ile/val or val/val were calculated in combination with null alleles of GSTM1 and GSTT1 or the *B allele of GSTM3, but there was no enhancement of risk. Gallstones were present in 57.5% of patients with gallbladder cancer, but there were no significant differences between allelic/genotype frequencies of the studied GST genes polymorphisms between patients with or without gallstones. To best of our knowledge, this is the first paper showing ile/val genotypes and val allele of GSTP1 to be associated with higher risk of gallbladder cancer.     

Interactions between Glutathione-S-Transferase M1, T1 and P1 polymorphisms and smoking,and increased susceptibility to esophageal squamous cell carcinoma

Background: A complex of genetic and environmental factors is involved in carcinogenesis of the esophageal squamous cell carcinoma (ESCC). Glutathione-S-Transferases (GSTs) are phase-II enzymes playing role in detoxification of carcinogen electrophiles. Genetic polymorphisms of GSTM1, GSTT1 and GSTP1 in association with some environmental factors and their impact on esophageal cancer susceptibility were assessed in the Iranian population. Methods: Genomic DNA of peripheral blood leukocytes from 148 confirmed esophageal cancer cases and 137 healthy individuals as control group was assayed for restriction fragment length polymorphisms in the GSTP1 loci by PCR amplification followed by digestion with Alw26I. Deletion of the GSTM1 and GSTT1 genes was detected by multiplex PCR. A data-mining method based on decision trees was applied to produce a predictive model of interactions between genotypes. Results: Smoking was independently associated with ESCC (p < 0.05, OR: 2.286, 95% CI = 1.311–3.983). Smoking along with GSTP1 Val/Val genotype was associated to ESCC (p < 0.001, OR: 3.886, 95% CI = 1.830–8.251), while non-smokers with GSTP1 Val/Val were significantly more frequent in non-cancerous group. (p = 0.007, OR: 0.507, 95% CI = 0.309–0.830). Conclusions: Data-mining methods are useful tools to map out a scheme for predicting complex relations and combinations of different genotypes. Genotyping analysis of GSTP1 together with assessment of smoking seems to be important in determining the risk of ESCC in the Iranian population.     

Are glutathione S transferases involved in DNA damage signalling? Interactions with DNA damage and repair revealed from molecular epidemiology studies

Glutathione S-transferases (GSTs) are members of a multigene family of isoenzymes that are important in the control of oxidative stress and in phase II metabolism. Acting non-enzymically, GSTs can modulate signalling pathways of cell proliferation, cell differentiation and apoptosis. Using a molecular epidemiology approach, we have investigated a potential involvement of GSTs in DNA damage processing, specifically the modulation of DNA repair in a group of 388 healthy adult volunteers; 239 with at least 5 years of occupational exposure to asbestos, stone wool or glass fibre, and 149 reference subjects. We measured DNA damage in lymphocytes using the comet assay (alkaline single cell gel electrophoresis): strand breaks (SBs) and alkali-labile sites, oxidised pyrimidines with endonuclease III, and oxidised purines with formamidopyrimidine DNA glycosylase. We also measured GST activity in erythrocytes, and the capacity for base excision repair (BER) in a lymphocyte extract. Polymorphisms in genes encoding three GST isoenzymes were determined, namely deletion of GSTM1 and GSTT1 and single nucleotide polymorphism Ile105Val in GSTP1. Consumption of vegetables and wine correlated negatively with DNA damage and modulated BER. GST activity correlated with oxidised bases and with BER capacity, and differed depending on polymorphisms in GSTP1, GSTT1 and GSTM1. A significantly lower BER rate was associated with the homozygous GSTT1 deletion in all asbestos site subjects and in the corresponding reference group. Multifactorial analysis revealed effects of sex and exposure in GSTP1 Ile/Val heterozygotes but not in Ile/Ile homozygotes. These variants affected also SBs levels, mainly by interactions of GSTP1 genotype with exposure, with sex, and with smoking habit; and by an interaction between sex and smoking. Our results show that GST polymorphisms and GST activity can apparently influence DNA stability and repair of oxidised bases, suggesting a potential new role for these proteins in DNA damage processing via DNA damage signalling.     

Combined effect of GSTM1, GSTT1 and GSTP1 polymorphisms on histological subtypes of lung cancer

Genetic polymorphisms are natural genetic variations in the gene sequence that occur at a frequency of >1% in the population. This genetic variability (polymorphisms) can be a factor in cancer risk. The functional polymorphisms in GST genes play an important role in susceptibility to lung cancer. In our previous study, we reported that the combination of certain genotypes of GSTM1, GSTT1 and CYP1A1 is associated with lung cancer. The study has been extended to investigate the potential role of polymorphism in GSTP1 alone or in combination with the status of GSTM1 and GSTT1 genes in the likelihood of development of lung cancer. A total of 302 subjects (151 cases and 151 controls) were evaluated. Using a case-control design, individuals were genotyped for GSTs using multiplex polymerase chain reaction and restriction fragment length polymorphism techniques. The data obtained were analyzed using multiple logistic regression. The combined 'at risk' genotypes of GSTM1 null and GSTT1 null in comparison with 'wild-type' genotypes seems to be associated with a greater risk of lung cancer, but the results are not significant (odds ratio (OR) 2.0, 95% confidence interval (CI) 0.68-5.96) and for squamous cell carcinoma (SqCC) it was 1.6-fold (OR 1.6, 95% CI 0.49-5.68). In summary, our case-control study of lung cancer revealed that the effect of these polymorphisms is not very marked for different genotypic combinations of GSTP1, GSTM1 and GSTT1 in the context of developing lung cancer in a north Indian population. However, the increased risk was limited to SqCC, and was not found for other histological subtypes. Further analyses on this topic are needed.     

Genetic polymorphisms of glutathione S-transferases are associated with ulcerative colitis in central China

The present study aimed to investigate the association between genetic polymorphisms of glutathione S-transferases (GSTs) and susceptibility to ulcerative colitis (UC) in central China. The prevalence of GSTM1, GSTT1, and GSTP1 gene polymorphisms were examined using polymerase chain reaction methods in 270 consecutive UC patients and 623 age- and sex-matched healthy controls. The frequencies of the GSTM1(null) and GSTT1(null) as well as GSTP1 (Val/Val) genotypes were significantly higher in UC patients than in the controls (70.74% vs. 41.74%, P = 0.0001; 64.82% vs. 47.19%, P = 0.0001; and 48.89% vs. 34.35%, P = 0.0004, respectively). When the UC patients were stratified according to clinical features, we found that the frequencies of the GSTT1(null) and GSTP1 (Val/Val) genotypes but not the GSTM1(null) genotype were significantly higher in patients with distal colitis than in extensive colitis (P = 0.0007, P = 0.001, and P = 0.271, respectively). However, these variant GST genotypes were not significantly linked to severity of the disease (P > 0.05). GST variant genotypes are strongly correlated with prevalence and extent but not with severity of UC in the Hubei Han population in central China.