Relationship between genotype and enzyme activity of glutathione S-transferases M1 and P1 in Chinese.

Glutathione S-transferases (GSTs) are the major detoxifying Phase II enzyme for eliminating electrophilic compounds. Mutations in GSTM1, GSTP1 and GSTT1 in Caucasian and GSTA1 in Chinese have been found to reduce enzyme activity. However, data on the impact of common genetic polymorphisms of GSTM1 and GSTP1 on enzyme activity in Chinese is lacking. This study aimed to investigate the effect of common GSTP1 and GSTM1 polymorphisms on erythrocyte GST activity in healthy Chinese (n = 196). GSTM1 null mutation (GSTM1*0) was analyzed by a PCR-Multiplex procedure, whereas GSTP1 313A-->G polymorphism (resulting in Ile105Val at codon 105) was analyzed by PCR-restriction fragment length polymorphism (RFLP) analysis. Erythrocyte GST activity was measured using 1-chloro-2,4-dinitro-bezene (CDNB) as the model substrate. The frequency of GSTM1 null genotype was 54.3% and the frequency of GSTP1-Ile/Ile, -Ile/Val, and -Val/Val genotype was 60.7%, 35.2% and 4.1%, respectively, with a frequency of 21.7% for the 105 valine allele. Age, gender and smoking did not significantly affect the erythrocyte GST activities. The mean erythrocyte GST enzyme activity for GSTP1*-Ile/Val genotype group (3.53 +/- 0.63U/gHb) was significantly lower than that for subjects with GSTP1-Ile/Ile genotype (4.25 +/- 1.07U/gHb, P = 0.004), while subjects with the GSTP1-Val/Val genotype had the lowest enzyme activity (2.44 +/- 0.67U/gHb). In addition, the GST activity in carriers of GSTM1*0/GSTP1-Ile/Ile was significantly higher than that of subjects inherited GSTM1*0/GSTP1-Ile/Val or GSTM1*0/GSTP1-Val/Val. However, there is no association between GSTM1 null mutation and reduced enzyme activity. GSTP1 codon 105 mutation led to reduced erythrocyte GST activity in Chinese. A combined GSTP1 and GSTM1 null mutations also resulted in significantly reduced GST activity. Further studies are needed to explore the clinical implications of GSTM1 and GSTP1 polymorphisms.     

Impact of phase I or phase II enzyme polymorphisms on lymphocyte DNA adducts in subjects exposed to urban air pollution and environmental tobacco smoke

Little is known about the impact of genetic variation on the genetic damage induced by urban air pollution or environmental tobacco smoke (ETS) in exposed populations. The levels of bulky DNA adducts ( 32P-postlabelling, nuclease P1 enrichment) and chromosomal aberrations were measured in lymphocytes of 194 non-smoking students living in the city of Athens, and the rural region of Halkida, Greece. In these individuals personal exposure to PAH was also measured. Furthermore, genetic polymorphisms were examined in cytochromes P450 1A1, 1B1, in the GSTM1, GSTP1 and GSTT1 as well as in microsomal epoxy hydrolase (EPHX) genes. Subjects with the CYP1*2A mutant genotype also suffering significant ETS exposure tended to exhibit higher adduct levels and % aberrant cells. In contrast, CYP1B1 polymorphisms seemed to have an impact on the DNA adduct levels only among individual with negligible ETS exposure. Subjects carrying both the CYP1*2A mutant genotype and the GSTM1 null genotype tended to have higher DNA adduct levels. A similar effect was also observed with the combined CYP1A1*2A/GSTP1 (Ile/Val) and the CYP1A1*2A/mEH "slow" polymorphisms. In both cases, the effect was more pronounced among subjects with higher levels of ETS exposure. Stepwise restriction of the observations to subjects characterised by (a) GSTP1 mutant, (b) GSTM1 null, (c) mEH "slow" (His139His) genotypes and (d) ETS exposure resulted in a significant trend of increasing DNA adduct levels only among individuals with at least one CYP1A1*2A mutated allele, illustrating the importance and complexity of gene-exposure and gene-gene interactions in determining the level of genotoxic damage on an individual levels.     

Glutathione S-transferases mu 1, theta 1, pi 1, alpha 1 and mu 3 genetic polymorphisms and the risk of colorectal and gastric cancers in humans

INTRODUCTION: Glutathione S-transferases (GSTs) are considered to be cancer susceptibility genes as they play a role in the detoxification of carcinogenic species. This study aimed to elucidate the influence of several GST polymorphisms on colorectal and gastric cancer risk. PATIENTS AND METHODS: GST mu1 (GSTM1), theta1 (GSTT1), pi1 (GSTP1), alpha1 (GSTA1) and mu3 (GSTM3) genotypes were determined in 144 colorectal cancer patients, 98 gastric cancer patients and 329 healthy control individuals. RESULTS: Colorectal cancer: the risk is greater for carriers of the GSTM1 null genotype (odds ratio [OR] = 1.91, 95% confidence interval [CI] = 1.25-2.91), for carriers of the GSTT1 null genotype (OR = 3.62, 95% CI = 2.34-5.62), and for simultaneous carriers of both GSTM1 and GSTT1 null genotypes (OR = 4.98, 95% CI = 2.77-9.00). Carriers of the GSTP1 104 Val/Val genotype are at a lower risk (OR = 0.31, 95% CI = 0.09-0.88). Among carriers of the GSTP1 Ile/Ile genotype, smoking increases the risk compared with nonsmoking (OR = 2.35, 95% CI = 1.11-4.99). Gastric cancer: the risk is greater for carriers of the GSTT1 null genotype (OR = 2.58, 95% CI = 1.53-4.36) and for simultaneous carriers of both GSTM1 and GSTT1 null genotypes (OR = 3.32, 95% CI = 1.62-6.77). Carriers of the GSTP1 104 Val/Val genotype are at a lower risk (OR = 0.20, 95% CI = 0.02-0.86). DISCUSSION: The GSTT1 null genotype, particularly if it is associated with the GSTM1 null genotype, greatly increases the risk for colorectal and gastric cancers. The GSTP1 104 Val/Val genotype may protect from both malignant tumors. CONCLUSION: This study indicates that GST polymorphisms, in particular the GSTM1/GSTT1 double-null haplotype, can be considered low-penetrance genes for gastrointestinal cancer.     

Relationship between glutathione S-transferase M1, P1 and T1 polymorphisms and early onset prostate cancer.

There is evidence suggesting that polymorphic variations in the glutathione S-transferases (GSTs) are associated with cancer susceptibility. Inter-individual differences in cancer susceptibility may be mediated in part through polymorphic variability in the bioactivation and detoxification of carcinogens. The GSTs have been consistently implicated as cancer susceptibility genes in this context. The GST supergene family includes several loci with well characterized polymorphisms. Approximately 50% of the Caucasian population are homozygous for deletions in GSTM1 and approximately 20% are homozygous for deletions in GSTT1, resulting in conjugation deficiency of mutagenic electrophiles to glutathione. The GSTP1 gene has a polymorphism at codon 105 resulting in an Ile to Val substitution which consequently alters the enzymatic activity of the protein and this has been suggested as a putative high-risk genotype in various cancers. We investigated the relationship between GST polymorphisms and young onset prostate cancer in a case-control study. GSTM1, GSTT1 and GSTP1 genotypes were determined for 275 prostate cancer patients and for 280 geographically matched control subjects. We found no significant difference in the frequency of GSTM1 or GSTT1 null genotypes between cases and controls. GSTP1 genotype was, however, significantly associated with prostate cancer risk: the Ile/Ile homozygotes had the lowest risk and there was a trend in increasing the risk with the number of 105 Val alleles: Ile/Val odds ratio (OR)= 1.30 (95% FCI 0.99-1.69), Val/Val OR = 1.80 (95% FCI 1.11-2.91); Ptrend = 0.026. These results suggest that the GSTP1 polymorphism may be a risk factor for developing young onset prostate cancer. We also found that carrying more than one putative high-risk allele in the carcinogen metabolizing GST family was associated with an elevated risk for early onset prostate cancer (OR 2.48, 95% FCI 1.22-5.04, Ptrend = 0.017).     

Polymorphisms of cytochrome P450 1A1, glutathione S-transferases M1 and T1 in a Turkish population

Intra-ethnic as well as inter-ethnic differences are known to exist in the frequencies of cytochrome P450 (CYP) 1A1, glutathione S-transferase (GST) M1, and GSTT1 gene polymorphisms with which associations have been shown for several cancers. In this study, CYP1A1 m2, GSTM1, and GSTT1 gene polymorphisms were determined among 133 healthy individuals of a Turkish population. On the basis of polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) methodology, the frequency of CYP1A1 m2 mutation was determined. The multiplex PCR protocol was used to determine the frequency of the deleted genotypes of both GSTM1 and GSTT1 genes. The frequencies of Ile/Ile (wild type), Ile/Val (heterozygous variant), and Val/Val (homozygous variant) CYP1A1 m2 genotypes were 90.2%, 9.8%, and 0%, respectively. The frequencies of the deleted GSTM1 (null) and GSTT1 (null) genotypes were 51.9% and 17.3%, respectively. These results show that the frequencies of the CYP1A1 m2, GSTM1, and GSTT1 gene polymorphisms in a Turkish population are similar to Caucasian populations.     

Glutathione S-transferase GSTP1 and cyclin D1 genotypes: association with numbers of basal cell carcinomas in a patient subgroup at high-risk of multiple tumours

We previously described associations between basal cell carcinoma (BCC) numbers and allelic variants at loci that mediate host response to ultraviolet radiation (UV). These associations were largely exerted in cases with the multiple presentation phenotype (MPP). This phenotype describes patients who present at their first or a later presentation with a cluster of BCC (2-10 new BCC). Remaining BCC cases have the single presentation phenotype (SPP) and may develop more than one BCC but only have single new lesions at any presentation. We proposed that the MPP cases comprise a high-risk group as they suffer significantly more lesions than SPP cases. We are attempting to determine, in the total BCC case group and subgroups, how many genes influence BCC numbers and their relative importance. In this study, we assessed the influence of two further candidates, glutathione S-transferase GSTP1 and cyclin D1 (CCND1), on tumour numbers in a total group of 457 patients comprising MPP and SPP cases. The relative importance of these genes in comparison with occupational UV exposure and host response (skin type) was also considered. We found that the frequencies of GSTP1 genotypes based on the Ile105 and Val105-expressing alleles and CCND1 AA, AG, GG genotypes were similar in MPP and SPP cases and that there were no significant associations between GSTP1 or CCND1 genotypes and BCC numbers in the total or SPP groups. However, in the MPP cases, GSTP1 Val105/Val105 was associated with more tumours (P = 0.05, reference GSTP1 Ile105/Ile105). Inclusion of skin type and indoor/outdoor occupation in the negative binomial regression models did not alter the associations of these genotypes with tumour numbers. DNA from 258 cases was analysed to identify GSTP1*A (Ile105-Ala114), GSTP1*B (Val105-Ala114), GSTP1*C (Val105-Val114) and GSTP1*D (Ile105-Val114). In SPP cases, there was no association between BCC numbers and GSTP1 BB, though the association with GSTP1 BC approached significance (P = 0.09). In MPP cases, GSTP1 BC was associated with BCC numbers (P = 0.03). We also found that the interaction term, GSTP1 Val105/Val105 with CCND1 AA, was associated with BCC numbers in the total (P = 0.001) and MPP (P = 0.006) but not SPP (P = 0.68) groups. In a stepwise model including GSTP1 Val105/Val105, CCND1 AA and their interaction terms as well as GSTM1, GSTT1 and CYP2D6 genotypes, skin type 1 and gender, the combination of genotypes was the best predictor of BCC numbers. These data suggest that study of further genes involved in cell-cycle control and protection from oxidative stress will be useful, particularly in high-risk subgroups.     

The influence of cytochrome P450 1A1 and glutathione S-transferase M1 genotypes on biomarker levels in coke-oven workers

The present study has the aim of evaluating gene-environment interaction on the levels of different biomarkers in coke-oven workers exposed to PAH. In order to assess whether the levels of some biomarkers (PAH-DNA adducts, nitro-PAH adducts to Hb and MN frequency) could be modulated by the genetic metabolic polymorphisms for CYP1A1 and GSTM1, we analysed in 76 coke-oven workers and 18 controls the CYP1A1 (MspI and Ile/Val sites) and the GSTM1 genotypes by a PCR assay. In individuals with shared set-up of CYP1A1 or GSTM1 genotypes, we analysed how the specified biomarkers correlated with total PAH exposure (urinary levels of 1-hydroxypyrene) both by a stratified analysis and logistic regression modelling. Statistically significant (P = 0.03 and P = 0.01) higher percentages of the more susceptible GSTM1− subjects compared to the GSTM1+ subjects and of the more susceptible CYP1A1 Ile/Val individuals compared to the CYP1A1 Ile/Ile individuals were detected for high levels of PAH-DNA adducts in the high exposure group (namely high levels of 1-OHP). A statistically significant association was observed between increased PAH-DNA adduct levels and the more susceptible GSTM1- genotype (P.O.R. = 4.18, P = 0.03) in a logistic regression modelling and a significant interaction between PAH exposure and GSTM1-genotype was found for PAH-DNA adducts. No effect of these metabolic genotypes was observed for MN frequency and nitro-PAH adducts to Hb. In conclusion, a gene-environment interaction between PAH exposure and two metabolic genotypes involved in activation (CYP1A1) and detoxification (GSTM1) of PAHs, respectively, has been identified. Received: 21 July 1999 / Accepted: 26 July 1999     

Individual sensitivity to DNA damage induced by styrene in vitro: influence of cytochrome p450, epoxide hydrolase and glutathione S-transferase genotypes

Styrene is a monomer of great commercial interest; its polymers and copolymers are used in a wide range of applications. In humans, styrene metabolism involves oxidation by cytochrome p450 monooxygenases (CYPs) to styrene-7,8-oxide, an epoxide thought to be responsible for the genotoxic effects of styrene exposure and detoxification by means of epoxide hydrolase (EH) and glutathione S-transferases (GSTs). The objective of this study was to investigate if genetic polymorphisms of metabolic enzymes modulate styrene-induced DNA damage in human leukocytes. CYP2E1, CYP1A1, EH, GSTP1, GSTM1 and GSTT1 polymorphisms were determined in 30 healthy donors and alkaline comet assay was carried out in isolated leukocytes exposed to 5 and 10 mM styrene, using 1% acetone as solvent control. The results obtained suggest that CYP1A1 m1, m2 and m4, CYP2E1 Dra I and GSTP1 (exons 5 and 6) polymorphisms may affect styrene induction of DNA damage in human leukocytes.     

Meta-analysis: glutathione-S-transferase allelic variants are associated with alcoholic liver disease

Aliment Pharmacol Ther 2011; 34: 1159–1172

Summary

Background Only a minority of alcoholics develop alcoholic liver disease (ALD) and allelic variants within genes encoding glutathione‐S‐transferases (GST) have been associated with ALD vulnerability with controversial results. Aim To assess the effects of GST polymorphisms on ALD by means of a genetic association study and meta‐analysis. Methods We retrieved published studies on the relationship between allelic variants within GST genes and ALD by means of electronic database search. A meta‐analysis was conducted in a fixed or random effects model. Calculations of odds ratios (OR) and their confidence intervals (CI), tests for heterogeneity of the results and sensitivity analysis, have been performed. A genetic association study comparing GSTM1, GSTT1 and GSTP1 genotype distribution among 279 alcoholics with or without ALD and 144 controls was also performed. Results Fifteen previous studies were identified analysing the association of ALD with polymorphisms within GST genes. After meta‐analysis, we found a significant association between the possession of the GSTM1 null allele and the presence of ALD (OR = 1.43; 95% CI: 1.14, 1.78; P = 0.002) among alcoholic patients. A significant association was also found for the possession of the GSTP1 Val/Val genotype and the presence of ALD (OR = 2.04; 95% CI: 1.09, 3.80; P = 0.03). Conclusions Our results suggest that, among alcoholics, carriers of GSTM1 null genetic variant or Val/Val genotype of Ile/Val GSTP1 polymorphism have an increased risk to suffer from alcoholic liver disease. The role of glutathione‐S‐transferase as a potential therapeutic target in alcoholic liver disease is reinforced.     

Protective role of glutathione S-transferase P1 (GSTP1) Val105Val genotype in patients with bronchial asthma

BACKGROUND: Glutathione S-transferase P1 (GSTP1), the abundant isoform of glutathione S-transferases (GSTs) in lung epithelium, plays an important role in cellular protection against oxidative stress and toxic foreign chemicals. It has been suggested that polymorphisms in the GSTP1 gene are associated with asthma and related phenotypes. As significant interindividual and interethnic differences exist in the distribution of xenobiotic-metabolizing enzymes, we have studied the GSTP1 Ile105Val polymorphism in patients with asthma in a Turkish sample. METHODS: GSTP1 Ile105Val polymorphism in exon 5 was determined in 210 patients with asthma (112 extrinsic and 108 intrinsic) and 265 control individuals without lung diseases and without history of allergy or atopy, using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) techniques. RESULTS: The proportion of GSTP1 Val105 homozygotes was significantly lower in the patients with asthma than in the control individuals (3.8% vs 12.1%). The odds ratio for GSTP1 Val105 homozygotes vs all other genotypes was 0.29 (95%CL 0.13-0.64, p = 0.01) for asthmatics. The distribution of GSTP1 Ile105Val genotypes and the frequency of GSTP1 Val105Val homozygotes (3.7% vs 3.9%) was not significantly different between extrinsic and intrinsic asthmatics. CONCLUSION: These results suggest a significant association between GSTP1 Ile105Val polymorphism and susceptibility to asthma and that the GSTP1 Val105Val genotype may be protective against developing this disease.     

GSTM1与GSTP1基因多态性对红细胞GST酶活性的影响

目的研究单独或结合GSTM1纯合缺失基因型时,不同GSTP1基因型对红细胞GST酶活性的影响。方法GST酶活性参照Habig等报道的方法用紫外分光光度法测定。用多重PCR分析GSTM1基因多态性,PCRRFLP检测GSTP15号外显子105位密码子基因多态性。结果汉族人的GSTM1纯合缺失频率为56.1%,GSTP1105I/I、I/V和V/V基因型频率分别为60.7%、35.2%和4.1%。杂合I/V基因型组的平均GST酶活性(3.53±0.63U·g-1Hb)比野生I/I基因型的GST酶活性低(4.25±1.07U·g-1Hb,P=0.000),比突变V/V基因型的GST酶活性高(2.44±0.67U·g-1Hb,P=0.004)。在GSTM1(-)基因组,GSTM1(-)/GSTP1I/I基因型携带者的GST酶活性比GSTM1(-)/GSTP1I/V或V/V携带者的高,而在GSTM1(+)组,两组间的酶活性无差异。不同年龄组平均GSTs活性无差异,而女性的平均GSTs活性比男性的平均值高,但差异无显著性。结论尽管其它GST酶可能会稀释GSTP1基因型对GST酶活性的效果,GST酶活性仍与GSTP1105Val基因型呈很强的相关性。     

The relationship among IL-13, GSTP1, and CYP1A1 polymorphisms and environmental tobacco smoke in a population of children with asthma in Northern Mexico

Exposure to environmental tobacco smoke (ETS) during early childhood increases the risk of developing asthma. The intention of this study was to genotype a population of children from Coahuila state in Northern Mexico and to determine whether polymorphisms of the CYP1A1, GSTP1, and IL13 genes are associated with exposure to ETS and subsequently a higher risk for asthma. IL13 plays an important role in the development of allergic response, particularly those related with airway inflammation. CYP1A1 and GSTP1 are xenobiotic-metabolizing enzymes induced by repeated exposure to toxicants. Polymorphisms of these genes have been related with ETS exposure and increased risk for asthma. To assess the effect of IL13 (-1112 C>T and Arg110Gln), GSTP1 (Ile105Val), and CYP1A1 (Ile462Val) on asthma risk and ETS exposure, we recruited 201 unrelated children and classified them into four groups: (1) control without ETS exposure; (2) control with ETS exposure; (3) with asthma and with ETS exposure and (4) with asthma and without ETS exposure. No association among ETS exposure, asthma, and the studied polymorphisms was denoted by multivariate analysis of this population.     

Glutathione S-transferase P1 Ile105Val polymorphism is associated with haematological toxicity in elderly rectal cancer patients receiving preoperative chemoradiotherapy

BACKGROUND: Increasing evidence suggests that common gene polymorphisms may influence the toxicity of various cytotoxic agents used in the treatment of cancer. OBJECTIVE: To evaluate the predictive value of acute toxicity of methylenetetrahydrofolate reductase 677T polymorphism, glutathione S-transferase P1 (GSTP1) substitution of isoleucine with valine at codon 105 (Ile105Val) polymorphism and the tandem repeat polymorphism in the thymidylate synthase gene promoter in elderly patients with rectal cancer receiving preoperative chemoradiotherapy (CRT). METHOD: From 1994 to 2002, 166 Caucasian patients underwent surgery following CRT for mid-low rectal cancer at a single institution, 42 (male-to-female ratio, 25 : 17) of whom were aged > or =65 years (median age 70 years, range 65-79). The pre-treatment clinical stage was tumour (T) stage 3-4 in 38 patients and node (N)-positive in 29 patients. Patients received external-beam radiotherapy with conventional fractionation and fluorouracil-based chemotherapy. Blood samples were used to extract and amplify DNA. Gene polymorphisms were determined by polymerase chain reaction and restriction enzyme digestion. Acute toxicity to preoperative therapy was reported according to the National Cancer Institute Common Toxicity Criteria, version 2. Univariate and multivariate analyses were performed using one-way analysis of variance and linear regression, respectively. RESULTS: Haematological toxicity (grade 1-2) was observed in 15 of 40 patients for whom toxicity data were available and gastrointestinal toxicity (grade 1-4) in 24 of these same 40 patients. At univariate analysis, female sex (p = 0.036) and GSTP1 Ile105Val (p = 0.0376) were associated with haematological toxicity. At multivariate analysis, GSTP1 Ile105Val polymorphism (p = 0.041) was the only factor found to be associated with haematological toxicity. Patients carrying the Val/Val genotype in the GSTP1 gene had a lower risk of haematological toxicity (odds ratio = 0.322, 95% CI 0.101, 0.957) than patients with the Ile/Ile genotype. CONCLUSION: GSTP1 Ile105Val polymorphism is a promising marker of potential haematological toxicity in elderly patients with rectal cancer receiving preoperative CRT.     

The influence of metabolic gene polymorphisms on urinary 1-hydroxypyrene concentration in Thai bus drivers

Polycyclic aromatic hydrocarbons (PAHs) are associated with an increased cancer risk. CYP1A1 and GSTs enzymes are important in metabolism of PAHs. Genetic polymorphisms of these enzymes are responsible for enzyme activity and concentration variation. The objectives of this study were to evaluate association of 1-OHP concentration with genetic polymorphisms of CYP1A1 and GSTs in Thai bus drivers. The results showed that 1-OHP levels in bus drivers were significantly higher than that in the control group. Significant difference in 1-OHP was found between smokers and non-smokers, in only bus drivers. Significantly increasing of 1-OHP levels were observed in bus drivers with CYP1A1 MspI and exon 7 variants. Whereas, bus drivers with GSTP1 Val and GSTM1 null genotypes showed decreasing in excretion of 1-OHP. No association between 1-OHP and polymorphisms of GSTT1 was found. This study indicated that 1-OHP concentrations were associated with exposure to air pollution, cigarette smoking and polymorphisms of CYP1A1, GSTM1 and GSTP1 genes.     

Polymorphisms of microsomal epoxide hydrolase and glutathione S-transferase P1 in a male Turkish population

Polymorphic genes encoding drug-metabolizing enzymes may account for interindividual differences in certain types of diseases especially cancer. In this study, microsomal epoxide hydrolase (EPHX1) and glutathione S-transferase P1 (GSTP1) gene polymorphisms were determined among 133 healthy males of a Turkish population. Frequencies of EPHX1 and GSTP1 gene polymorphisms were determined by using the polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) method. The observed genotype frequencies of EPHX1 exon 3 were Tyr113Tyr:50.4%, Tyr113His: 42.1%, His113His: 7.5% and EPHX1 exon 4 were His139His: 69.2%, His139Arg: 28.6%, Arg133Arg: 2.2%. GSTP1 exon 5 genotype frequencies were Ile105Ile: 58.7%, Ile105Val: 35.3%, Val105Val: 6.0% and GSTP1 exon 6 genotype frequencies were Ala114Ala: 85.0%, Ala114Val: 14.3%, Val114Val: 0.7%. These results reveal that the frequencies of EPHX1 and GSTP1gene polymorphisms in a small sampling of males within a Turkish population are similar to European Caucasian populations.     

Genetic polymorphisms of CYP2D6, CYP1A1, GSTM1 and p53 genes in a unique Siberian population of Tundra Nentsi

The purpose of this study was to establish the frequencies of CYP2D6, CYP1A1, GSTM1 and p53 polymorphic genotypes in Tundra Nentsi, which comprises the small group of indigenous people belonging to Northern Mongoloids and Caucasians of Western Siberia. A total number of 102 Tundra Nentsi individuals and 96 Caucasians of Western Siberia were genotyped by means of polymerase chain reaction-based assays. Mutated alleles comprising CYP2D6*4, CYP1A1Val, GSTM1*0 and p53Pro were analysed along with the wild-type alleles. The results showed the intermedial position of CYP2D6*4 allele frequency in Tundra Nentsi, compared to Caucasians and Orientals (0.07 versus 0.2, P = 0.0003; 0.07 versus 0.003, P = 1 x 10(-6), respectively). Thus, our data indicate that the intermedial position of Tundra Nentsi between Orientals and Caucasians most likely shows the Caucasian ancestral origin of CYP2D6*4 allele. Comparative analysis of p53Pro allele frequency showed the pronounced ethnic differences with geographic gradient. Though the frequency of p53Pro allele ranged from 0.17 in Tundra Nentsi up to 0.3 in Caucasians of Western Siberia (P = 0.002), which is in agreement with the previously reported radial distribution of the known genetic markers. No differences were found in the CYP1A1Val allele distribution among Caucasians of Western Siberia and Caucasoid populations presented in other studies, whereas the frequency of Val allele in Nentsi was 1.5-fold higher (P = 0.076) compared to the Japanese group. It was found that the frequency of GSTM1 null genotype in Tundra Nentsi was only 39.8%. The frequency of GSTM1 null genotype in females was higher than in males (0.27 and 0.50, respectively) but that difference was not statistically significant. Comparative analyses of the distribution of putative markers towards cancer susceptibility, CYP1A1Val, GSTM1*0 and p53Pro alleles, have shown that the healthy Tundra Nentsi population (Northern Mongoloids) have a low number of p53Pro alleles and GSTM1*0/*0 genotypes and a high level of CYP1A1Val alleles. Further investigations of gene polymorphisms in isolated Northern native populations would be valuable in clarifying the origin of Northern natives. All this is important for comparative analyses of pharmacogenetic data in Mongoloid populations.     

Genetic polymorphisms in glutathione S-transferase (GST) superfamily and arsenic metabolism in residents of the Red River Delta, Vietnam

To elucidate the role of genetic factors in arsenic metabolism, we investigated associations of genetic polymorphisms in the members of glutathione S-transferase (GST) superfamily with the arsenic concentrations in hair and urine, and urinary arsenic profile in residents in the Red River Delta, Vietnam. Genotyping was conducted for GST ω1 (GSTO1) Ala140Asp, Glu155del, Glu208Lys, Thr217Asn, and Ala236Val, GST ω2 (GSTO2) Asn142Asp, GST π1 (GSTP1) Ile105Val, GST μ1 (GSTM1) wild/null, and GST θ1 (GSTT1) wild/null. There were no mutation alleles for GSTO1 Glu208Lys, Thr217Asn, and Ala236Val in this population. GSTO1 Glu155del hetero type showed higher urinary concentration of As^V than the wild homo type. Higher percentage of DMA^V in urine of GSTM1 wild type was observed compared with that of the null type. Strong correlations between GSTP1 Ile105Val and arsenic exposure level and profile were observed in this study. Especially, heterozygote of GSTP1 Ile105Val had a higher metabolic capacity from inorganic arsenic to monomethyl arsenic, while the opposite trend was observed for ability of metabolism from As^V to As^III. Furthermore, other factors including sex, age, body mass index, arsenic level in drinking water, and genotypes of As (+ 3 oxidation state) methyltransferase (AS3MT) were also significantly co-associated with arsenic level and profile in the Vietnamese. To our knowledge, this is the first study indicating the associations of genetic factors of GST superfamily with arsenic metabolism in a Vietnamese population.     

Genotoxic damage in hospital workers exposed to ionizing radiation and metabolic gene polymorphisms

Of all workers exposed globally to synthetic sources of radiation, medical personnel represent the largest group, but receive relatively low doses. Accidental or therapeutic acute radiation exposure of humans was observed to induce various forms of cytogenetic damage, including the possibility of increasing the incidence of micronuclei (MN) and chromosomal aberrations (CA). The aim of this study was to assess occupationally induced chromosomal damage in a large population of hospital workers exposed to low doses of ionizing radiation (IR). The cytokinesis-block MN and comet assays were used to examine peripheral blood lymphocytes (PBL) of 31 exposed workers to IR and 33 control subjects corresponding in gender, age, and smoking. Glutathione S-transferases (GSTM1, GSTT1, and GSTP1) are postulated to be involved in the detoxification of endogenous and exogenous genotoxicants. The association between these biomarkers and polymorphic genes of xenobiotic metabolizing enzymes was thus also assessed. MN frequency was significantly higher in the exposed subjects compared controls. Comet assay results showed a significant increase of tail length in workers exposed to IR. Data obtained suggest that GSTM1, GSTT1, and GSTP1 polymorphism do not modify significantly the genotoxic potential of IR. Therefore, the exposed medical personnel need to carefully apply radiation protection procedures and minimize, as low as possible, IR exposure to avoid possible genotoxic effects.     

Genetic polymorphisms influence variability in benzene metabolism in humans

The role of genetic polymorphism in modulating urinary excretion of two benzene metabolites, i.e. trans,trans-muconic acid (t,t-MA) and S-phenylmercapturic acid (PMA), has been investigated in 59 non-smoking city bus drivers, professionally exposed to benzene via vehicle exhausts. Exposure to benzene was determined by personal passive samplers (mean +/- SD = 82.2 +/- 25.6 micrograms/m3), while internal dose and metabolic rate were evaluated by measuring urinary excretion of unmodified benzene (mean +/- SD = 361 +/- 246 ng/l), t,t-MA (mean +/- SD = 602 +/- 625 micrograms/g creatinine), and PMA (mean +/- SD = 5.88 +/- 4.76 micrograms/g creatinine). Genetic polymorphism at six loci encoding cytochrome-P450-dependent monooxygenases (CYP2E1 and CYP2D6), glutathione-S-transferases (GSTT1, GSTP1 and GSTM1) and NAD(P)H:quinone oxidoreductase (NQOR) was determined by polymerase chain reaction-based methods. No evidence emerged for a possible role of CYP2E1, GSTM1 and GSTP1 polymorphisms in determining the wide differences observed in the rate of benzene biotransformation. Conversely, a significantly higher t,t-MA urinary excretion was found to be correlated to, GSTT1 null genotype, and a significantly lower PMA excretion was detected in the subjects lacking NQOR activity and in the CYP2D6 extensive-metabolizers. Many biological (i.e. age and body burden) or lifestyle factors (i.e. rural or urban residence, use of paints and solvents, medication, alcohol and coffee intake), also taken into account as potential confounders, did not influence the correlations found. These findings suggest that CYP2D6, GSTT1 and NQOR polymorphisms contribute in explaining the metabolic variability observed in our sample. Therefore, these polymorphisms should be regarded as potential risk factors for benzene-induced adverse health effects.     

Glutathione S-transferase P1 genetic polymorphisms and susceptibility to childhood acute lymphoblastic leukaemia

Glutathione S-transferase pi (GSTP1) is involved in the metabolism of carcinogens. We assessed the association of GSTP1 genetic polymorphisms and the susceptibility to childhood acute lymphoblastic leukaemia (ALL) by conducting a case-control study on 278 ALL patients and 303 healthy controls, both of French-Canadian origin. The carriers of the GSTP1*B variant (only the Val105 substitution) were found to be associated with an increased risk of ALL [odds ratio (OR) = 1.5, 95% confidence interval (CI) 1.1-2.0], whereas the GSTP1*C variant (both Val105 and Val114) was underrepresented in cases. Thus, genetic variants of GSTP1 that are expressed at the protein level appear to contribute differently to the risk of ALL, probably because of distinct substrate specificities. When combined with other GST genotypes, we found that the combination of GSTP1*B and GSTM1 null genotypes further increased the risk of ALL (OR = 2.1; 95% CI-1.3-3.4). These findings suggest that GSTP1 variants (alone or combined with other GSTs) represent significant genetic determinants of childhood ALL.