Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants generated from combustion of carbon-based matter. Upon ingestion, these molecules can be bioactivated by cytochrome P450 monooxygenases to oxidized toxic metabolites. Some of these metabolites are potent carcinogens that can form irreversible adducts with DNA and other biological macromolecules. Conjugative enzymes, such as glutathione S-transferases or UDP-glucuronosyltransferases, are responsible for the detoxification and/or facilitate the elimination of these carcinogens. While responses to PAH exposures have been extensively studied for the bioactivating cytochrome P450 enzymes, much less is known regarding the response of glutathione S-transferases in mammalian systems. In this study, we investigated the expression and activity responses of murine hepatic glutathione S-transferases to benzo[ a]pyrene exposure using global proteomics and activity-based protein profiling for chemoproteomics, respectively. Using this approach, we identified several enzymes exhibiting increased activity including GSTA2, M1, M2, M4, M6, and P1. The activity of one GST enzyme, GSTA4, was found to be downregulated with increasing B[ a]P dose. Activity responses of several of these enzymes were identified as being expression-independent when comparing global and activity-based data sets, possibly alluding to as of yet unknown regulatory post-translational mechanisms.

OBJECTIVE

Many studies have reported the role of glutathione S-transferase Mu 1 (GST M1) polymorphism with ovary cancer risk, but the results remained controversial.

METHODS

To derive a more precise estimation of the relationship, a meta-analysis was performed. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association between GSTM1 polymorphism and ovary cancer risk. A total of 11 studies including 2709 cases and 3599 controls were also involved in this meta-analysis.

RESULTS

When all the eligible studies were pooled into this meta-analysis, no significant association between ovary cancer risk and GSTM1 polymorphism was found (OR = 1.010, 95% CI = 0.911-1.121, P heterogeneity = 0.174, P = 0.848).

CONCLUSIONS

Our meta-analysis supports that the GSTM1 polymorphism is not contributed to the risk of ovary cancer from currently available evidence.

Introduction: Glutathione S-transferase (GST) is one of the major detoxifiers in alveoli. Polymorphism in GST genes can influence the ability of individuals to suppress oxidative stress and inflammation. The present study was aimed to explore the hypothesis that the genetic polymorphisms of GST T1, M1 and P1 are associated with the severity of the mustard lung in the sulfur mustard-exposed individuals. Methods: Blood samples were taken from 185 sulfur mustard-exposed and 57 unexposed subjects. According to the stage of the mustard lung, sulfur mustard-exposed patients were categorized in the mild/moderate and severe/very severe groups. A multiplex PCR method was conducted to identify GSTM1 and GSTT1 null genotypes. To determine the polymorphisms of GSTP1 in exon 5 (Ile105Val) and exon 6 (Ala114Val), RFLP-PCR method was performed. Results: The frequency of GSTM1 homozygous deletion was significantly higher in the severe/very severe patients compared with the mild/moderate subjects (66.3% vs. 48%, P = 0.013). The GSTM1 null genotype was associated with the severity of mustard lung (adjusted odds ratio [OR], 2.257; 95% CI, 1.219-4.180). There was no significant association between GSTT1 and GSTP1 polymorphisms with the severity of the mustard lung. Conclusion: The different distribution of GSTM1 null genotype in severe/very severe and mild/moderate groups indicated that the severity of the mustard lung might be associated with the genetic polymorphism(s).

Chronic obstructive pulmonary disease (COPD) is a complex disorder influenced by multiple genetic and environmental factors, as well as their interactions. Since elevated oxidative stress and protease activity characterize the pathogenesis of COPD, variants of genes that can affect these processes have been commonly studied in COPD. However, interactions among genes that can influence oxidative stress and protease activity remain poorly investigated in COPD. The aim of this study was to look into the role of functional variants in matrix metalloproteinases (MMPs) 1, 9, and 12 in the occurrence and/or modulation of COPD, and to analyze their interactions with glutathione S-transferases (GSTs) M1, T1, and P1 in the pathogenesis of COPD in Serbians. The MMP1 rs1799750 G>> GG, MMP9 rs3918242 C>> T, and MMP12 rs2276109 A>> G variants were analyzed by direct detection methods. Gene-gene interactions between variants in MMPs and GSTs were assessed using a case-control model. Our results showed association of the MMP1 GG/GG genotype with COPD (p = 0.036, OR = 2.50). Gene-gene interactions between the GSTM1 null and MMP1 GG (p = 0.028, OR = 2.99) and the GSTM1 null and MMP12 AA variants (p = 0.015, OR = 3.82) were found to significantly increase the risk of COPD occurrence. Furthermore, the MMP12 G variant was found to modify the age of COPD onset (p = 0.025, OR = 3.30), while interaction between the GSTM1 null and MMP9 T variants was found to modify the severity of disease (p = 0.019, OR = 4.83). To our best knowledge, this is the first study revealing several gene-gene interactions affecting oxidative stress and protease activity in the pathogenesis of COPD.

Glutathione S-transferases (GSTs) are a group of enzymes involved in the detoxification process of carcinogens and other substances. The genes encoding isoenzymes M1 and T1 have "null" alleles, which are polymorphic in humans. Our purpose was to examine whether the GSTM1 and GSTT1 homozygous null genotypes have an impact on the response to recombinant human erythropoietin (rhuEpo) treatment in MDS patients. We analyzed lymphocyte DNA samples from 27 patients with all types of myelodysplastic syndromes (MDS) at the time of diagnosis. All patients were scheduled to receive rHuEpo in doses of 150 u/Kg/day for a period of 12 weeks in order to obtain and maintain stable responses. A multiplex polymerase chain reaction (PCR) was used to genotype both GSTM1 and GSTT1 simultaneously, in responders and non-responders to rhuEpo with respect to various pretreatment parameters: haemoglobin, white blood cell count, platelets, serum erythropoietin, transfusion requirements and bone marrow blasts. The data obtained were evaluated by chi2 test and odds ratio were extracted. Twelve out of 27 evaluated patients demonstrated an erythroid response (44%). Nine out of the 12 patients (75%) responding after 12 weeks of treatment had GSTM1 null genotype (OR=3.4). In contrast, only 1 responder (8.3%) was homozygotes of GSTT1 null genotype. Furthermore, no statistically significant difference in the response rate of the different MDS subgroups was observed. Our results suggest that a treatment with rHuEpo may be effective in achieving a stable erythroid response in MDS patients who carry an homozygous deletion of the GSTM1 gene.

The purpose of this study was to investigate the use of human and animal subcellular liver fractions in an in vitro evaluation of carcinogenic risk. The bioactivation and bioinactivation of the known genotoxic carcinogen aflatoxin B1 by human, mouse and rat liver preparations was investigated using the SCE assay in human lymphocytes as a genotoxic endpoint. There was a 10-fold variation in SCE response (1.1-11.6 SCE/Cell) in human mononuclear leucocytes (MNLs) after aflatoxin B1 was activated by human liver microsomes (n = 6). Activation correlated with the CYP1A2 phenotype of livers (r = 0.8; p < 0.05), but there was no correlation with either GST M1 genotype or epoxide hydrolase phenotype. Mouse liver microsomes activated aflatoxin B1 to a greater extent [(1 micro M) 12.8 +/- 2.51 SCE/Cell] than either rat [(10 micro M) 12.0 +/- 3.84 SCE/Cell or human (L25) [(10 micro M) 8.8 +/- 2.00 SCE/Cell liver microsomes. The addition of mouse liver cytosol and reduced glutathione (GSH) significantly (p < 0.001) reduced aflatoxin B1-dependent genotoxicity, whereas the addition of either human or rat cytosol (+GSH) was without effect. These data indicate that species variation in both bioactivation and bioinactivation can exist. Therefore there is a necessity for careful selection of activation systems from species whose biochemical profile reflects that of man.

Glutathione S-transferase (GST) polymorphism (M1 = 215 bp and T1 = 480 bp) can cause liver damage and increase the risk of cancer. In this study, voltage programming (VP)-based microchip electrophoresis (ME) with a laser-induced fluorescence (LIF) detector was developed to detect specific sizes of DNA fragments. The optimum conditions for a single-channel microchip were as follows: 4 kV for 0-9.5 s, 1.5 kV for 9.5-15.5 s, and 4 kV for 15.5-30 s. Next, these conditions were applied to another microchip that was constructed with many channels making possible simultaneous parallel detection. Finally, GST genes extracted from human blood were amplified by polymerase chain reaction (PCR) and were introduced into the multi-channel microchip. Target DNA molecules amplified by only 10 PCR cycles could be detected by the VP-based multi-channel ME method, but not by slab gel electrophoresis (SGE). In addition, the migration time for ME was <15 s, which was 700 times faster than conventional SGE. The developed VP-based multi-channel ME method with LIF detection was demonstrated to be an effective, rapid analysis technique for highly sensitive and high-throughput screening of GST genes.

OBJECTIVE

To construct prokaryotic expression system for expressing, purifying and identifying truncated fragment of extra-cellular segment of sodium pump alpha3 subunit with pGEX-6P-1 GST gene fusion system in Escherichia coli by in-fusion technology.

METHODS

According to the conservative sequence of M1-M2 and M3-M4 extra-cellular gene fragments of sodium pump a3 subunit, which published in GenBank, a serial of primers and gene fragments was designed, and directly synthesized to fuse the above two gene fragments. The fusion gene was fused with gene-specific primers by PCR, and then fusion gene fragment was fused into the single stranded homology regions of vector pGEX-6P-1 by in-fusion cloning to construct recombinant vector pGEX-Trf-alpha3 (Truncated fragment of extracellular segment of sodium pump alpha3 subunit, Trf-alpha3). After DH10bac was transferred with it, the pGEX-Trf-alpha3 plasmid was purified and identified by PCR and sequenced. Then the recombinant plasmid pGEX-Trf-alpha3 was expressed in E. coli BL21 cells, inducted by IPTG. GST-Trf-alpha3 fusion protein was purified with Glutathione Sepharose 4B purifying system and analyzed by SDS-PAGE.

RESULTS

The results of PCR and sequencing demonstrated that the M1-M2 and M3-M4 extra-cellular gene was inserted in plasmid pGEX-6P-1 vector successfully. And the sequence was correct. Protein sequence analysis showed that the GST-Trf-alpha3 fusion protein was consisted of 262 amino-acid residues. Relative molecular mass in theory was 33.22 X 10(3). The amount of recombinant protein was 10% of the total bacteria protein. The soluble fusion protein was about 80.8%. After affinity purification, the purity of GST-Trf-alpha3 fusion protein was over 95%. There was some extent binding activity between GST-Trf-alpha3 fusion protein and ouabain, but the activity was very low.

CONCLUSIONS

Prokaryotic expression system for expressing truncated fragment of extra-cellular segment of sodium pump alpha3 subunit with pGEX-6P-1 GST gene fusion system in Escherichia coli by in-fusion technology had been constructed. The purified method had also established. High purified GST-Trf-alpha3 fusion protein was obtained. These have found the foundation of further study on its biological function and potential pharmacology function.

BACKGROUND

In view of our previous studies showing an independent association of genetic polymorphisms in folate, xenobiotic, and toll-like receptor (TLR) pathways with the risk for systemic lupus erythematosus (SLE), we have developed three statistical models to delineate complex gene-gene interactions between folate, xenobiotic, TLR, and signal transducer and activator of transcription 4 (STAT4) signaling pathways in association with the molecular pathophysiology of SLE.

METHODS

We developed additive, multifactor dimensionality reduction (MDR), and artificial neural network (ANN) models.

RESULTS

The additive model, although the simplest, suggested a moderate predictability of 30 polymorphisms of these four pathways (area under the curve [AUC] 0.66). MDR analysis revealed significant gene-gene interactions among glutathione-S-transferase (GST)T1 and STAT4 (rs3821236 and rs7574865) polymorphisms, which account for moderate predictability of SLE. The MDR model for specific auto-antibodies revealed the importance of gene-gene interactions among cytochrome P450, family1, subfamily A, polypeptide 1 (CYP1A1) m1, catechol-O-methyltransferase (COMT) H108L, solute carrier family 19 (folate transporter), member 1 (SLC19A1) G80A, estrogen receptor 1 (ESR1), TLR5, 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR), thymidylate synthase (TYMS). and STAT4 polymorphisms. The ANN model for disease prediction showed reasonably good predictability of SLE risk with 30 polymorphisms (AUC 0.76). These polymorphisms contribute towards the production of SSB and anti-dsDNA antibodies to the extent of 48 and 40%, respectively, while their contribution for the production of antiRNP, SSA, and anti-cardiolipin antibodies varies between 20 and 30%.

CONCLUSIONS

The current study highlighted the importance of genetic polymorphisms in folate, xenobiotic, TLR, and STAT4 signaling pathways as moderate predictors of SLE risk and delineates the molecular pathophysiology associated with these single nucleotide polymorphisms (SNPs) by demonstrating their association with specific auto-antibody production.

Recent epidemiological studies proposed that the glutathione S-transferase (GST) M1-null genotype may contribute to diseases associated with oxidative stress. The genetic polymorphism exhibited by the GSTM1 may be an important factor in risk toward oxidant chemicals. In this study, we investigated the effect of GSTM1-null genotype in lymphocyte and oxidative stress-dependent inhibition of platelet aggregation. To determine whether GSTM1 deficiency is a genetic determinant of cell toxicity toward oxidant chemicals, lymphocytes were incubated in vitro with low levels of benzo(a)pyrene (BaP), cumene hydroperoxide (CumOOH), or trans-stilbene oxide that do not decrease cell viability, and were assessed for oxidative damage and for the lymphocyte-dependent inhibition of platelet response. Malondialdehyde and carbonyl levels, and the oxidation of cisparinaric acid, were used as biomarkers of oxidative stress in lymphocytes. Following stimulation by BaP or CumOOH, when peroxidation-dependent changes in these parameters were compared between the GSTM1-null genotype and the positive genotype, no significant differences were found between the two genotypes. On the other hand, preincubation of the lymphocytes with BaP or CumOOH attenuated their inhibitory action on ADP-induced platelet aggregation. However, our results indicate that lymphocytes of individuals with the GSTM1-null genotype have greater inhibitory activity on platelet function after exposure to BaP, but not CumOOH, although they are not more susceptible to in vitro oxidative stress.

OBJECTIVE

In this study we conducted a cross-sectional study and reported on the distribution of two common genetic polymorphisms of the PON1 gene and two common genetic polymorphisms of the GST gene as well as the association between those polymorphisms and other predictors in a population of floriculture workers from Kunming city.

METHODS

136 pesticide-exposed farmers were recruited. PON1 and GST T1, M1 genotype were determined by means of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

(1) Compared with exposure group, the GLB in control group was higher (β = -0.16, t = -2.30, P = 0.02), but the A/G in control group was lower (β = 0.14, t = 2.09, P = 0.04); (2) Compared with the persons who carried QQ genotype, the accumulative symptom scores were lower in the persons who carried RR genotype (t = -2.78, P = 0.006); (3) Compared with GST T1 carriers, non-carriers' GLB (β = -0.20, t = -3.01, P = 0.00) and IgG (β = -0.20, t = -3.01, P = 0.00) were higher, but the A/G was lower; (4) The abnormities of cardiograms among people who had been exposed to pesticides were higher compared to people who did not expose to any pesticides (β = 1.147, P = 0.042).

CONCLUSIONS

PON1-192 and GST T1 gene were associated with the farmers health condition after pesticides exposure.

Workers in epoxy resin, synthetic leather, and printed circuit board manufacturing plants are exposed to epichlorohydrin (ECH), or dimethylformamide (DMF), or both. ECH, an alkylating agent, has been shown to cause malignancy in animals, but its genotoxicity in humans is unclear. DMF is a well-known hepatotoxic chemical, although evidence of its genotoxicity in humans is also limited. In this study, we examined the effects of exposure to ECH and DMF on sister chromatid exchange (SCE) in plant workers, in order to examine the genotoxicity of these two agents. Because the genotoxicity of certain agents can be modulated by metabolic traits, we also investigated influence of the glutathione S-transferase (GST) micro (GST M1) and GST theta (GST T1) genes on the genotoxicity of ECH and DMF. A total of 85 male plant workers were included in this study. The subjects were divided into five exposure groups, based on their job titles and the airborne ECH and DMF concentrations in their areas of work. A questionnaire was administered to obtain detailed occupational, smoking, alcohol consumption, and medication histories. Standardized cytogenetic methods were used to determine the frequency of sister chromatid exchange (SCE) in peripheral blood lymphocytes. GST M and GST T1 genotypes were identified using polymerase chain reaction (PCR). In analysis, smoking was significantly associated with increased SCE frequency (P<0.01). Workers with high ECH exposure also had significantly higher SCE frequencies than those with low or no ECH exposure (P<0.05). However, DMF exposure was not associated with SCE frequency. The GST M1 null genotype was also found to be associated with an increased SCE frequency (P = 0.06). We conclude that ECH exposure may be associated with genetic toxicity and that DMF does not appear to be genotoxic.

Tofacitinib is an orally administered medication with a mechanism of action that involves JAK1, JAK2, JAK3 and TYK2 pathway inhibition. There is an increasing interest in the use of this drug in the management of psoriatic arthritis, following its success and wide use as an approved treatment option for patients with rheumatoid arthritis. Recently, Guo et al. (2019) reported a well-designed and executed in vitro metabolism study entitled, "Tofacitinib is a Mechanism-Based Inactivator of Cytochrome P450 3A4" to elucidate the mechanism-based inactivation of tofacitinib by trapping reactive metabolites generated in microsomal incubations. The results identified tofacitinib as a concentration-, time-, and NADPH-dependent irreversible inhibitor of CYP3A4 where glutathione (GSH) and superoxide dismutase/catalase offered minor or little protection against the CYP3A4 inactivation. Of the epoxide and α-keto-aldehyde intermediates of tofacitinib were trapped and characterized in microsomal incubations, and aldehyde intermediate was proposed to be the key for the CYP3A4 enzyme inactivation. While the present data will promote more scientific thinking and rationalization to possibly explain the mechanistic basis of the side effects induced by tofacitinib, especially liver injury, there are certain aspects of the data which need introspection to understand and validate the proposed concept. The intent of this letter is to highlight the concerns of undermining the significant contribution of the epoxide intermediate as well as the role of glutathione trapping process in the enzyme inactivation. Analysis of the results inferred that the observed higher enzyme activation by tofacitinib as compared to analogue 2 (that forms only aldehyde intermediate) could be because of its ability to generate both epoxide and aldehyde. Secondly, it has been inferred that the nucleophilic agent GSH exhibited limited ability to attenuate tofacitinib-induced CYP3A4 inactivation. This could be due to the absence of cytosolic glutathione-s-transferases (GST) for GSH adduct formation in the metabolic process, as cytosolic GSTs are functionally different from microsomal GSTs. Furthermore, in Scheme 2, it has been depicted that the epoxide intermediate conjugates with NAC to form two isomers. However, the possible isomers have been named as M1/M2/M3 indicating that there is a chance of formation of three isomers. Thus, Scheme 2 needs clarification for the readers who would be interested to know the probable mechanism of formation of three isomers.

Recent evidence indicates that chronic, low-dose exposure to mixtures of pesticides can cause adverse responses in a variety of cells, tissues and organs, although interactions between pesticides circulating in the blood and cancer cells remain largely unexplored. The aim of this study was to investigate the potential of a mixture of four pesticides to induce multidrug resistance against the chemotherapeutic agents cisplatin, 5-fluorouracil and temozolomide in the human U87 glioblastoma cell line, and to explore the molecular mechanisms underlying this resistance. We found that the repeated administration of the pesticide mixture (containing the insecticides chlorpyrifos-ethyl and deltamethrin, the fungicide metiram, and the herbicide glyphosate) induced a strong drug resistance in U87 cells. The resistance was durable and transferred to subsequent cell generations. In addition, we detected a significant over-expression of the ATP-binding cassette (ABC) membrane transporters P-gp/ABCB1 and BRCP/ABCG2 as well as a glutathione-S-transferase (GST)/M1-type cellular detoxification function, known to have important roles in multidrug resistance, thus providing molecular support for the acquired multidrug resistance phenotype and shedding light on the mechanism of resistance. We further determined that there was lower mortality in the resistant brain tumor cells and that the mitochondrial apoptosis pathway was activated at a lower rate after chemotherapy compared to non-resistant control cells. In addition, multidrug-resistant cells were found to have both higher motility and wound-healing properties, suggesting a greater metastatic potential. Our results suggest that the investigation of P-gp, BRCP and GST/M1 multidrug resistance gene expression and/or protein levels in biopsy specimens of brain tumor patients who were at risk of pesticide exposure could be beneficial in determining chemotherapy dose and prolonging patient survival.

Keywords: Chemotherapy; Glioblastoma multiforme; Multidrug resistance; Pesticide mixture; U87.

OBJECTIVE

We examine the relationship between nicotine dependence (ND) and ND-related medical disease and polymorphisms by deletion in genes that encode glutathione S-transferases (GSTs), e.g. GSTM1 and GSTT1. Individuals with homozygous gene deletions show deficiencies in GSTs enzyme activities impairing detoxification.

METHODS

This study comprised 182 tobacco users and 182 controls (neversmokers). GSTM1 and GSTT1 polymorphisms were assessed using a Multiplex- PCR based protocol.

RESULTS

Logistic regression analyses showed a significant association between ND and the GSTM1 and GSTT1 null genotypes. There were no significant associations between GSTT1, GSTM1 and GSTT1/M1 genetic variants and the Fagerström test for ND, age at onset, smoking cessation or a family history of ND. Patients with ND had increased rates of a family ND history and an increased prevalence of cardiovascular disease, hypertension, and lung disease. The null genotypes were associated with hypertension (i.e. GSTT1 × ND interaction), diabetes type 2 (i.e. GSTM1 × GSTT1 interaction), lung disease (i.e. GSTM1 × ND interaction) and cancer (i.e. GSTT1). The results show that GST null genotypes may confer protection against ND while they increase risk towards ND-related medical disorders.

Insufficient response to oxidative stress in placenta is proposed as a contributing factor for preeclampsia (PE) development. Glutathione S-transferases (GST) have significant role in detoxification processes. Conflicting results were published by several research groups regarding GST T1 and GST M1 deletion polymorphism as risk factors for PE. The aim of the present meta-analysis was to get a better understanding of the impact of these polymorphisms in preeclampsia development. To identify relevant case-control studies the authors team searched Clarivate Analytics Web of Science, Scopus, PubMed, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, major subject journals and grey literature. Pooled odds ratios and 95% confidence intervals for GST M1 and GST T1 deletion polymorphism and preeclampsia were derived from random effects models. This meta-analysis included ten eligible studies. The pooled analyses showed no association between GST M1/GST T1 deletion polymorphisms and susceptibility to PE. Even though high heterogeneity was founded among results for GST M1 and double null genotypes, Egger's and Begg's tests (0.17 and 0.18, respectively) revealed no statistical evidence of publication bias among included studies. The present updated systematic review and meta-analysis found no association between GST M1 and GST T1 deletion polymorphism and PE risk.

Keywords: gene; glutathione S-transferase M1; glutathione S-transferase T1; meta-analysis; polymorphism; preeclampsia.

Although peroxisomal bifunctional enzyme (enoyl-CoA hydratase/L-3-hydroxyacyl-CoA dehydrogenase; BE) is a positive marker for peroxisome proliferation, it is completely absent or expressed very weakly in rat hepatic preneoplastic and neoplastic lesions induced by peroxisome proliferators (PP). After administration of PP for 8-15 weeks, some rats exhibit BE-negative preneoplastic foci but other rats do not. In the present study, to investigate the involvement of glutathione S-transferase (GST) M1 gene polymorphism in interindividual differences in susceptibility to PP, we developed a method to determine the genotypes of rats. We then examined whether rats with one type encoding 198Asn-199Cys (NC-type) or another encoding 198Lys-199Ser (KS-type) exhibit differences in clofibrate (CF) susceptibility. After administration of 0.3% CF for 6 weeks or more, BE-negative foci were found immunohistochemically in KS/KS-type rats, but not in NC/NC-type rats. The number of BE-negative foci in KS/KS rats was 15.3 +/- 9.0 foci/cm2 of liver section after 6 weeks of CF administration, and the values did not alter thereafter. The mean areas of BE-negative foci in KS/KS rat livers increased during the period from 6 to 60 weeks. At weeks 30 and 60, almost all BE-negative foci exhibited a clear cell phenotype, a type of preneoplastic hepatic lesion. BE-negative foci were devoid of peroxisome proliferator-activated receptor alpha, whereas surrounding tissues were positive for the receptor. These results indicate that rats that are polymorphic for the GST M1 gene exhibit different susceptibilities to CF in vivo.

OBJECTIVE

To elucidate whether the gene polymorphisms of glutathione S-transferase (GST) M1, T1, and P1 are associated with the development of exudative age-related macular degeneration.

METHODS

The authors genotyped 35 white patients with exudative age-related macular degeneration and 159 healthy controls. Genomic DNA from peripheral blood was examined using polymerase chain reaction and defined for the genetic polymorphisms of GST.

RESULTS

No association was observed between GSTM1, GSTT1, and GSTP1 polymorphisms and age-related macular degeneration risk (p>0.05). The frequencies of the combination of the GSTM1 (null) and GSTP1 (mutant), GSTM1 (null), and GSTT1 (null) genotype polymorphisms in patients with exudative age-related macular degeneration differed greatly from those of the control group (p=0.001 OR [95% CI]: 7.70 [2.28-25.98] and p=0.007 OR [95% CI]: 3.88 [1.51-10.02], respectively).

CONCLUSIONS

The present study suggests that the GSTM1 (null) and GSTT1 (null), GSTM1 (null), and GSTP1 (mutant) combinations may be a genetic risk factor for the development of exudative age-related macular degeneration. However, the potential role of GST polymorphisms as a marker of susceptibility to age-related macular degeneration needs further studies in a larger number of patients. (Eur J Ophthalmol 2006; 16: 105-10).

Background: Functional variants of the xenobiotic-metabolizing genes (XMG) might modulate breast cancer (BC) risk by altering the rate of metabolism and clearance of myriad types of potent carcinogens from the breast tissue. Despite mounting evidence on the role of XMG variants on BC risk, the current knowledge regarding their influence on BC development is still fragmentary.

Methods: The present study examined the candidate genetic variants in CYP1A1, NQO1, GST-T1, GST-M1, and GST-P1 in 1002 subjects (502 BC patients and 500 disease-free women). PCR-RFLP was employed to genotype the mono-nucleotide variation in CYP1A1, NQO1, and GST-P1, and allele-specific PCR was used to detect the deletion polymorphism in GST-T1 and GST-M1 genes.

Results: Regarding CYP1A1-M1 polymorphism, the heterozygous TC and mutant CC genotype conferred 1.47-fold (95% CI 1.13-1.91, p = 0.004) and 1.84-fold (95% CI 1.17-2.91, p = 0.009) elevated risk of BC. GST-T1 null genotype was associated with increased BC risk (OR 1.47; 95% CI 1.02-2.11, p = 0.037). For the NQO1 C609T variant, the mutant T allele was associated with BC risk with an odds ratio of 1.22 (95% CI 1.02-1.48, p = 0.034). Combinatorial analysis indicated that the presence of NQO1*2 (CT), CYP1A1-M1 (CC), and GST-P1 rs1695 (AG) genotypes conferred 16.7-fold elevated risk of BC (95% CI 3.65-76.85; p < 0.001). Moreover, GST-M1 null genotype was associated with the development of larger primary breast tumors.

Conclusion: Xenobiotic-metabolizing gene polymorphisms may play a crucial role in mammary carcinogenesis in South Indian women.

Keywords: Breast cancer; CYP1A1; GST-M1; GST-P1; GST-T1; NQO1; Polymorphisms.

Background Epigenetic represents a study of occurred heritable gene expression changes without changing in the DNA sequence. It includes DNA methylation and miRNA expression that attract increasing attention as potential links between the genetic and environmental determinants of health and disease. Pesticide exposure is associated with adverse health effects and DNA methylation due to oxidative stress induced following its exposure. This study aimed to define the association of genetic polymorphisms of XRCC1, PON1, GSTP1 and GST genes with global genes DNA methylation in urban and rural occupationally pesticides exposed workers. Methods This study included 100 pesticides exposed workers; 50 rural sprayers (RE) and 50 urban researchers (UE). Controls included equal numbers. DNA methylation of global genes was evaluated by pyrosequencing assay. XRCC1, PON1 and GSTP1 genotyping were assessed by PCR-RFLP, and GST M1 and T1 were performed by PCR. Results The results of this study revealed that most genotypes in XRCC1, PON1, GSTP1 and GST genes were associated with LINE-1 hypomethylation among UE group. However, heterozygote genotypes (Gln-Arg and Ile-Val) in XRCC1 and GSTP1 genes, respectively, were associated with LINE-1 hypermethylation among UE compared with other corresponding genotypes. Only GSTT1 polymorphism recorded a significant change in percent methylation of Alu elements among urban and rural groups. Conclusion Urbanization could play an additional risk for epigenetic changes associated with pesticide exposure, and that could be attributed to the quality of life including their dietary habits, working and living in closed areas, and their exposure to extra pollutions emitted from urbanization sources.

Keywords: XRCC1; DNA methylation; GST; PON1; gene polymorphism; pesticides exposed workers.

The complex of human cell defence systems against gamma-radiation was investigated: DNA repair, antiradical system, GST-family M1 and T1, radioadaptive response. Were compared in repair-deficient cells the action of natural (carlic extract) and synthetic (crown-compound) antimutagens. New approach related to the detection of the activity of different defence systems is developing. It helps to estimate the individual sensitivity to mutagens.

Use of lead-adulterated opium has become one of the major sources of lead poisoning in Iran. This study was designed to assess clinical effects and oxidative stress and its association with GSTM1, GSTT1, NQO1, and ALAD genes polymorphisms and blood lead level (BLL) in lead-adulterated opium users. The oxidative stress status in 192 opium users with lead poisoning symptoms measured and compared with 102 healthy individuals. Gluthatione S-transferase (GST)-M1 and -T1 genes deletion, NQO1 rs1800566, and δ-aminolevulinic acid dehydratase (ALAD) rs1800435 polymorphisms were determined using PCR and PCR-RFLP. The relation between the polymorphisms, BLL, and oxidative stress parameters were analysed using multivariate linear regressions. The common symptoms of lead toxicity were gastrointestinal and neurologic complications. Oxidative stress was significantly higher in opium addicts and lipid peroxidation significantly correlated with BLL. There was significant association between ALAD rs1800435 and BLL, and the BLL was significantly lower in the patients with ALAD 1-2 genotype. Use of lead-adulterated opium causes high frequency of lead toxicity symptoms, hematological and biochemical abnormalities, and oxidative stress which are associated with BLL. Route of opioid use and the polymorphism of rs1800435 in ALAD gene are the major determinants of BLL in lead-adulterated opium users.

The "mu loop," an 11-residue loop spanning amino acid residues 33-43, is a characteristic structural feature of the mu class of glutathione transferases. To assess the contribution of the mu loop to the structure and function of rat GST M1-1, amino acid residues 35-44 (35GDAPDYDRSQ44) were excised by deletion mutagenesis, resulting in the "Deletion Enzyme." Kinetic studies reveal that the Km values of the Deletion Enzyme are markedly increased compared with those of the wild-type enzyme: 32-fold for 1-chloro-2,4-dinitrobenzene, 99-fold for glutathione, and 880-fold for monobromobimane, while the Vmax value for each substrate is increased only modestly. Results from experiments probing the structure of the Deletion Enzyme, in comparison with that of the wild-type enzyme, suggest that the secondary and quaternary structures have not been appreciably perturbed. Thermostability studies indicate that the Deletion Enzyme is as stable as the wild-type enzyme at 4 degrees C and 10 degrees C, but it rapidly loses activity at 25 degrees C, unlike the wild-type enzyme. In the temperature range of 4 degrees C through 25 degrees C, the loss of activity of the Deletion Enzyme is not the result of a change in its structure, as determined by circular dichroism spectroscopy and sedimentation equilibrium centrifugation. Collectively, these results indicate that the mu loop is not essential for GST M1-1 to maintain its structure nor is it required for the enzyme to retain some catalytic activity. However, it is an important determinant of the enzyme's affinity for its substrates.