Enzyme-linked immunoassays (ELISAs) based on the double-antibody sandwich technique have been developed for the quantitative analysis of the major human cytosolic class Pi, Mu and Alpha glutathione transferases (GSTs). The procedures were optimized with respect to antibody concentration for coating of plates as well as other parameters in order to achieve high sensitivity and accuracy. No cross-reactivity was detected between members of the three different classes of GSTs or among the Mu class GSTs M2-2, M3-3 and M4-4 with the ELISA for GST M1-1. The ELISAs have been applied to establish the cytosolic GST profiles of 10 cell lines and to monitor the plasma GST levels in cancer patients. The results revealed that the class Pi GST was the dominant isoenzyme in six (LS 174T, HCT-8, Hu 549 Pat, K-562, U-937 and Hu 549) out of nine tumor cell lines and immortalized hepatocytes (Chang Liver). The isoenzymes A1-1 and M1-1 were determined to be the major GST components in Hep G2 and HeLa cells, respectively. In a clinical study, the majority of the patients with urinary bladder cancer were found to have increased plasma levels of both GST A1-1 and GST P1-1 (10/15), while patients with renal cancer frequently showed increases only in GST P1-1 (5/8). The results demonstrate that the ELISAs are suitable for analyzing GST phenotypes in both normal and tumor cells and in monitoring plasma levels of GSTs in cancer patients.

BACKGROUND

There are some evidences indicating DNA damage by oxidant and mutant agents has an essential role in the chronic renal failure and end stage renal disease (ESRD). To investigate the possible association of GSTs variants with ESRD, we investigated the frequency of GST- T1, M1, and P1 genotypes, and the level of malondialdehyde (MDA) in patients with ESRD.

METHODS

The present case-control study consisted of 136 ESRD patients treated with maintenance hemodialysis and 137 gender- and age-matched, unrelated healthy controls from the population of west of Iran. The GST- T1, M1, and P1 genotypes were determined in all individuals using multiplex-PCR and PCR-RFLP. The level of MDA was measured by high-performance liquid chromatography (HPLC).

RESULTS

We found that GSTM1 and GSTT1 null genotypes (GSTT1-/GSTM1-) increased the risk of ESRD by 1.8 times (p < 0.001) and the increased risk of ESRD for GSTM-null (T1+-M1-) genotype was 3.04 times (p = 0.002). ESRD patients carriers the GST (GSTM1-null + GSTT1-null + GST-null) genotypes compared to GST normal genotype increased the risk of ESRD by 3.3 (p < 0.001) times. ESRD patients carriers of GST-null, GSTM1-null, and GSTT1-null genotypes had greater MDA concentration compared with the same genotypes of control subjects. Our results indicated that the GST-null allele (GSTT1-null/GSTM1-null) is a risk factor for ESRD and carriers of this allele have high levels of MDA.

CONCLUSIONS

Our findings indicate that oxidative stress, impairment of the antioxidant system and abnormal lipid metabolism may play a role in the pathogenesis and progression of ESRD and its related complications. These data suggest that patients with ESRD are more susceptible to vascular diseases.

BACKGROUND

Deletion types of genetic variants of glutathione S-transferase (GST) M1 and T1, the GSTM1 null and GSTT1 null which are risk factors for certain cancers, have been ubiquitously found in human populations but their worldwide distribution pattern is unclear.

METHODS

To perform a meta-analysis, a systematic search for the literature on GSTM1 and GSTT1 null genotypes was done to identify 63 reports for 81 human populations. Relationships between the GSTM1 and GSTT1 null genotype frequencies and the absolute latitude of 81 populations were tested by Spearman's rank correlation coefficient.

RESULTS

A significant positive correlation was detected between the GSTM1 null genotype frequency and the absolute latitude (r=0.28, p-value <0.05), whereas the GSTT1 null genotype frequency and absolute latitude showed a significant negative correlation (r= -0.41 p-value <0.01). There was no correlation between the frequencies of GSTM1 and GSTT1 null genotype in each population (r= -0.029, p-value=0.80).

CONCLUSIONS

Latitudinal clines of the distribution of the GSTM1 and GSTT1 null genotypes may be attributed to the result of gene-environmental adaptation. No functional compensation between GSTM1 and GSTT1 was suggested by the lack of correlation between the null frequencies for GSTM1 and GSTT1.

The oxidation of linoleic acid produces several products with biological activity including the hydroperoxy fatty acid 13-hydroperoxyoctadecadienoic acid (13-HPODE), the hydroxy fatty acid 13-hydroxyoctadecadienoic acid (13-HODE), and the 2,4-dienone 13-oxooctadecadienoic acid (13-OXO). In the present work, the peroxidase activity of glutathione transferases (GST) A1-1, M1-1, M2-2, and P1-1(Val 105) toward 13-HPODE has been examined. The alpha class enzyme is the most efficient peroxidase while the two enzymes from the mu class exhibit weak peroxidase activity toward 13-HPODE. It was also determined that the conjugated diene 13-HODE is not a substrate for GST from the alpha and mu classes but that 13-HODE does inhibit the GST-catalyzed conjugation of CDNB by enzymes from the alpha, mu, and pi classes. Finally, both 13-HODE and 13-OXO were shown to be inducers of GST activity in HT-29 and HCT-116 colon tumor cells. These data help to clarify the role of GST in the metabolic disposition of linoleic acid oxidation products.

Colorectal cancer (CRC) is reported to be the third most common cancer worldwide and the fourth most common cause of cancer related deaths. CRC is considered to be a multifactorial disease whose risk varies due to the complex interaction between individual genetic basis and exposure to multiple endogenous factors. Glutathione S-transferases are pro-carcinogenic in CRC and are required for the conjugation between chemotherapeutics and broad spectrum xenobiotics. One hundred and eleven patients with CRC and 128 control subjects without any cancer history were enrolled in this study. Multiplex PCR was applied to determine polymorphisms for the GSTT1 and M1 genes, and PCR-RFLP was applied for the GSTP1 (Ile105Val) gene polymorphism. Values <0.05 were defined as statistically significant. We detected a significant high correlation between predisposition for CRC and presence of the Ile/Ile genotype of the GSTP1 (IIe105Val) gene polymorphism, but we did not find a significant relationship between predisposition for CRC and GSTT1 and M1 deletion polymorphisms. In addition, we did not determine a relationship between GSTT1, M1 and P1 gene polymorphisms and any clinicopathological features of CRC. GSTT1 null/GSTM1 positive and GSTT1 null/GSTM1 positive/GSTP1 Ile/ Ile genotypes were significantly higher in the patient group. Our results revealed that there is no relationship among CRC, its clinicopathologic features, and GSTT1 M1 gene polymorphisms. However, there was a significant correlation between CRC and the GSTP1 Ile/Ile genotype. Further studies with larger patient groups are required to delineate the relationships between GST gene polymorphisms and the clinicopathologic features of CRC in Turkey.

Azathioprine (AZA) is increasingly being prescribed to rheumatoid arthritis (RA) patients. Following oral administration, AZA is converted into its active form. Inflammatory bowel disease (IBD) and systemic lupus erythematosus (SLE) patients with low thiopurine (S)-methyltransferase (TPMT) activity tend to respond well to AZA therapy. In a previous study of Japanese SLE patients under low-dose AZA therapy, the group with the 94C>A mutation in inosine triphosphatase (ITPA) showed greater improvement in their disease activity index. However, it is not yet clear how genotypes relate to responsiveness to RA treatment. The genotypes ITPA 94C>A, TPMT*3C, NUDT15 595C>T, GST-M1, GST-T1 and MRP4/ABCC4 2269G>A of Japanese patients with RA were determined. The relationship between these genotypes and response to AZA therapy was evaluated using the Disease Activity Score 28 (DAS28) and various medical data. Of the 22 patients 15 had the ITPA 94C/C genotype, 7 had the ITPA 94C/A genotype, none had the TPMT*3C mutation, 4 had the NUDT15 595C>T mutation, 8 had the GST-M1 and T1 null genotypes and 9 had the MRP4/ABCC4 2269G>A mutation. Changes in DAS28 at 6 months after baseline were similar in both ITPA genotype groups. However, the maintenance dose of AZA was significantly lower in the C/A group than in the C/C group (0.85±0.30 mg/kg/day vs. 1.2±0.46 mg/kg/day, respectively; p = 0.043). The ITPA 94C/A group showed the same response to RA treatment as the C/C group, but at a lower dose. This demonstrates that RA patients with the ITPA 94C>A mutation are more responsive to AZA.

Glutathione-S-transferases (GST) are key phase II detoxifying enzymes that play critical roles in protection against products of oxidative stress and against electrophiles. Glutathione S-transferase mu (GST-M1) and theta (GST-T1) are isoforms of glutathione transferase enzymes that participate in the metabolism of a wide range of chemicals. Deletion variants that are associated with a lack of enzyme function exist at both these loci. The frequencies of homozygous GSTM1 and GSTT1 deletion carriers are very high in most of the populations studied to date. The aim of this study was to investigate the frequencies of GSTM1 and GSTT1 genotypes among the Turabah population in Saudi Arabia in comparison with the data published for some other Arabic populations. The subjects consisted of 164 unrelated healthy individuals from the Turabah population. GST genotyping was performed by multiplex polymerase chain reaction-based methods. The GSTM1 deletion homozygosity was 56.1% and GSTT1 deletion homozygosity was 20.7%, while the GSTM1 and GSTT1 double-deletion homozygosity was 11.0%. Comparison with published data from Bahraini, Lebanese, and Tunisian populations demonstrated no significant difference for GSTM1 between these populations. The GSTT1 null-allele frequency was significantly lower than those for the Lebanese and Tunisian populations (P = 0.001) but similar to that for the Bahraini population (P = 0.099). Characterization of GST genetic polymorphisms in the Saudi population may aid in genetic studies on the association of GSTM1 and GSTT1 polymorphisms with disease risks and the pharmacogenetics of chemotherapy.

Genetic diversity in drug metabolism and disposition is mainly considered as the outcome of the inter-individual genetic variation in polymorphism of drug-xenobiotic metabolizing enzyme (XME). Among the XMEs, glutathione-S-transferases (GST) gene loci are an important candidate for the investigation of diversity in allele frequency, as the deletion mutations in GST M1 and T1 genotypes are associated with various cancers and genetic disorders of all major Population Affiliations (PAs). Therefore, the present population based phylogenetic study was focused to uncover the frequency distribution pattern in GST M1 and T1 null genotypes among 45 Geographically Assorted Human Populations (GAHPs). The frequency distribution pattern for GST M1 and T1 null alleles have been detected in this study using the data derived from literatures representing 44 populations affiliated to Africa, Asia, Europe, South America and the genome of PA from Gujarat, a region in western India. Allele frequency counting for Gujarat PA and scattered plot analysis for geographical distribution among the PAs were performed in SPSS-21. The GST M1 and GST T1 null allele frequencies patterns of the PAs were computed in Seqboot, Gendist program of Phylip software package (3.69 versions) and Unweighted Pair Group method with Arithmetic Mean in Mega-6 software. Allele frequencies from South African Xhosa tribe, East African Zimbabwe, East African Ethiopia, North African Egypt, Caucasian, South Asian Afghanistan and South Indian Andhra Pradesh have been identified as the probable seven patterns among the 45 GAHPs investigated in this study for GST M1-T1 null genotypes. The patternized null allele frequencies demonstrated in this study for the first time addresses the missing link in GST M1-T1 null allele frequencies among GAHPs.

Investigators have demonstrated that the mutagen sensitivity assay, based on the quantification of bleomycin (BLM)-induced chromatid breaks in short-term cultured peripheral lymphocytes, can be a marker of cancer susceptibility. Although many factors can contribute to variability in human biomonitoring studies, genetic susceptibility (the influence of polymorphic metabolising genes on response to environmental mutagens) should be considered whenever appropriate. Glutathione-S-transferases (GSTs) encode a family of detoxifying phase II enzymes catalysing the conjugation of glutathione to electrophilic compounds. Studies on Caucasians indicate that about 45% of individuals lack the glutathione-S-transferase M1 (GSTM1, null) enzyme, and are therefore, theoretically at a higher risk to the toxic effects of chemicals. The aim of the present study was to investigate this hypothesis further by evaluating whether the GSTM1 genotype influences the background [corrected] level of DNA damage and the induction of chromosomal aberrations by BLM in peripheral-blood lymphocytes. The alkaline comet assay was used to evaluate background levels of DNA damage in unstimulated lymphocytes while standard cytogenetic techniques were used in mitogen-stimulated lymphocytes treated with BLM. Without BLM treatment, individuals with the GSTM1 null genotype had no significant difference in frequencies of damaged cells by comparison to individuals with the GSTM1 genotype. Also, no significant differences between the two groups of individuals (GSTM1 positive and GSTM1 null) were observed for BLM-induced chromosomal aberrations.

Phase I metabolic enzyme CYP1A1 plays an important role in xenobiotics metabolism and has been extensively studied as a cancer risk biomarker. CYP1A1 is polymorphic and its four variants, e.g., CYP1A1* 2 A, CYP1A1* 2C, CYP1A1* 3 and CYP1A1* 4 with trivial names m1, m2, m3, and m4 respectively, are most commonly studied for cancer link. Gene- gene interaction studies combining polymorphisms of this enzyme with those of phase II detoxifying enzymes, especially glutathione S- transferases (GSTs) revealed greater risk for cancer susceptibility. Variants of CYP1A1 have also been found to be associated with chemotherapeutic adverse- effects. Results of these studies, however, remained largely contradictory mainly because of lack of statistical power due to involvement of small sample size. Strongly powered experimental designs involving gene- gene, gene- environment interactions are required in order to validate CYP1A1 as reliable cancer- biomarker.

Many cyanobacterial species can produce cyanotoxins, among which mycrocistins (MC) are a group of ≈100 congeners of hepatotoxic cyclic heptapeptides. MC-RR differs from MC-LR, the most studied congener only for one residue (arginine vs leucine), resulting in a ten-fold difference in the acute toxicity in mice. Although humans may be exposed to MC through several routes and kinetics appeared to be the major factor affecting congener-specific toxicity, little is known on MC metabolism. The accepted pathway for MC detoxication is GSH conjugation: here the MC-RR conjugation with GSH catalyzed by 5 recombinant human GSTs and human liver cytosol (HLC) has been characterized and appeared to be more efficient than MC-LR conjugation. The catalytic efficiency score is T1-1>A1-1≈P1-1>M1-1>A3-3 (0.161-0.056pmol GSMC-RR (μgproteinminμM)(-1)). In HLC the spontaneous reaction is favored vs the enzymatic one (ratio 3:1) at physiological GSH content. However, at low MC-RR concentrations, representative of repeated oral exposure, and low GSH content (down to 0.05mM), possibly associated to exposure to drugs or in patients affected by several pathologies, the relevance of the enzymatic reaction progressively increases, providing the predominant contribution to MC-RR detoxication.

The expression of thymidylate synthase (TS) in human cancer tissues has been suggested to be a prognostic factor for patients receiving 5-fluorouracil-based chemotherapy. We generated monoclonal antibodies to both recombinant and native TS and analyzed the epitopes on the TS molecule. Two monoclonal antibodies were obtained from recombinant human TS proteins (RTSMA1 and RTSMA2) and two monoclonal antibodies raised to native TS in human cancers (NTSMA1 and NTSMA2) were obtained, and were found to have a high affinity and specificity for TS proteins. To identify the human TS epitope that these monoclonal antibodies recognized, we constructed plasmids to produce full-length and two partially deleted TS proteins fused to glutathion-S-transferase (GST). Western blot analysis showed that RTSMA1 and 2 only reacted with full-length TS and NTSMA1 and 2 reacted with all three recombinant TS proteins, suggesting that the epitopes of the former were located at C-terminal sites (D186-V313), and those of the latter were at N-terminal sites (M1-M61). The RTSMA 1 and 2 epitopes were more accurately mapped using 8 oligopeptides to the region of I267 to L282 which was situated at the surface of the TS protein. Highly sensitive detection of human TS was also possible by sandwich ELISA using a combination of different types of antibody rather than a single type. In conclusion, different type monoclonal antibodies to human TS protein may contribute to the detection of TS in cancer patients.

In this study, DNA extracted from frozen urine was used in the analysis of polymorphisms in genes coding for xenobiotic-metabolizing enzymes (XMEs). These included single-nucleotide polymorphisms (SNP) in microsomal epoxide hydrolase (mEH), that is, substitutions of tyrosine by histidine in codon 113 (Y113H) and histidine by arginine in codon 139 (H139R), and deletion polymorphisms in glutathione S-transferase (GST) M1 and T1 genes. The concentration of DNA extracted from urine of a Ghanaian population (n = 91) exposed to aflatoxins in their diet ranged from 82.5 to 573 ng/ml urine. Polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP) procedures were used for the characterization of mEH polymorphisms, whereas a multiplex PCR method was utilized to identify GST deletion polymorphisms. In total, 91% and 94% of 91 samples were genotyped for mEH exon 3 and exon 4 polymorphisms, respectively. In the multiplex analysis of GST polymorphisms, 94% and 91% of 91 individuals were genotyped for GSTM1 and GSTT1 polymorphisms, respectively. The polymorphisms in the mEH exon 4, GSTM1 and GSTT1, were not in Hardy-Weinberg equilibrium (HWE) except for mEH exon 3. Representative genotypes identified by PCR-RFLP were cloned and sequenced, then confirmed by comparison with reference sequences of human DNA published in the GenBank BLAST database. These results demonstrate that XMEs can be genotyped from urine with reliable accuracy and may be useful in cancer and molecular epidemiology studies.

Endometriosis is a polygenic/multifactorial disease caused by interactions between multiple genes and the environment. Findings from studies evaluating the association between the glutathione S-transferase (GST) M1/T1 null genotype and susceptibility to endometriosis are inconsistent. This meta-analysis updated and reevaluated the possible associations between GSTM1, GSTT1 and combined GSTM1/GSTT1 (null genotype versus wild-type) gene polymorphisms and susceptibility to endometriosis. The PubMed, Embase and Chinese BioMedical Literature databases and Google Scholar were searched for case-control genetic association studies on GSTM1/GSTT1 (null genotype versus wild-type) gene polymorphisms and endometriosis in comparison with non-endometriosis or healthy controls. Fixed-effect and random-effect meta-analytical techniques were conducted for the outcome measure and subgroup analyses. The meta-analysis demonstrated significant associations between the GSTM1 [odds ratio (OR)=1.56; 95% confidence interval (CI): 1.25-1.95; P<0.0001), GSTT1 (OR=1.31; 95% CI: 1.02-1.68; P=0.037) and GSTM1/GSTT1 (OR=1.68; 95% CI: 1.29-2.17; P<0.0001) null genotypes and increased risk for endometriosis. The results suggest that the GSTM1, GSTT1, and combined GSTM1/GSTT1 null genotypes increase susceptibility to endometriosis. Additional well-designed studies and precise analyses are warranted to confirm these findings.

Glutathione transferases (GSTs) are enzymes involved in the resistance of tumor cells to bifunctional alkylating cytostatic drugs. We investigated the melphalan sensitivity together with activity and cellular concentration of GST isoenzymes of human melanoma cell line RPMI 8322 in different phases of the cell cycle. By centrifugal elutriation three cell fractions containing different proportions of cells in the G1 phase were isolated. Melphalan sensitivity was estimated by the colony formation assay. The cell fraction with the largest proportion of G1 cells was more sensitive to the drug than the fractions enriched in S and G2 cells. The GST activity of the cell fractions was measured with 1-chloro-2,4-dinitrobenzene (CDNB) as substrate and the concentrations of GST P1-1, GST M1-1 and GST A1-1 were quantitated by use of isoenzyme-specific ELISA. The results show that there were less GST activity and lower GST P1-1 and A1-1 concentrations in the G1 cell enriched fraction, demonstrating a cell cycle dependence of GST expression. Thus, the cell fraction most sensitive to melphalan had the highest proportion of G1 cells and displayed the lowest GST activity, suggesting that the cell cycle dependent sensitivity to melphalan may at least partially depend on the expression of GSTs.

1. Glutathione S-transferase (GST) activity in the cytosol of renal cortex and tumours from eight men and eight women was measured using 1-chloro-2,4-dinitrobenzene (CDNB) as a substrate. GST activities ranged from 685 to 2192 nmol/min/mg protein in cortex (median 1213) and from non-detectable (minimum 45) to 2424 nmol/min/mg protein in tumours (median 469). The activities in the tumours were lower than those in the normal cortices (p < 0.05). 2. In men, the activity in the cortical cytosol was in all cases higher than that measured in the corresponding tumours (p < 0.05). In women, the difference in activity between cortices and tumours was not significantly different (p>> 0.05). 3. The age of the patients ranged from 42 to 81 years (median 62) and was not found to play a role in the levels of GST activity observed in cortex or in renal tumours from either sex. 4. Immunoblotting and immunohistochemical studies confirmed that GST-alpha was the predominant form expressed both in normal cortex and tumour and probably accounted for most of the GST activity present in these samples. GST-mu and GST-phi were expressed in both tumours and normal cortex and, while in some cases the level of expression in the cortices was higher than that found in the tumours, the reverse was also observed. Within the GST-mu class, GST M1/M2 was only detected in one sample (tumour), which showed the highest overall expression of GST-mu. GSTM3 was the predominant isoenzyme of the mu class in normal and tumour tissue, whereas GTM4 and GSTM5 were not detected. 5. These differences could have functional significance where xenobiotics or cytotoxic drugs are specific substrates for the different classes of GSTs.

A homozygous gene deletion at the glutathione-S-transferase (GST) M1 locus of genomic DNA isolated from the peripheral blood was investigated for its relationship with lung and oral cancer using the polymerase chain reaction (RCR) technique. DNA samples were prepared from 91 healthy controls, 53 lung cancer patients and 48 oral cancer patients. As for the genotype, 38 of 91 healthy controls (41.7%), 27 of 53 lung cancer patients (50.9% [p>> 0.05], odds ratio 1.45, 95% confidence interval 0.73-2.86) and 26 of 48 oral cancer patients (54.2% [p>> 0.05], odds ratio 1.65, 95% confidence interval 0.82-3.32) were GSTM1 deletion types. When male-smoker patients and healthy controls were analyzed, the frequency of GSTM1 deletion genotype was 41.6% in the healthy controls and 52.2% (p>> 0.05, odds ratio 1.53, 95% confidence interval 0.58-4.14), 54.5% (p>> 0.05, odds ratio 1.68, 95% confidence interval 0.45-6.26), and 50.0% (p>> 0.05, odds ratio 1.40, 95% confidence interval 0.55-3.60) in pulmonary squamous cell carcinoma, small cell carcinoma, intraoral squamous cell carcinoma patients, respectively. Thus, the GSTM1 deletion genotype as a host factor predisposing to lung and oral cancer could not be confirmed in this study.

Glutathione S-transferases (GST) are antioxidant enzymes and oxidative stress markers in oral carcinogenesis. They present a system of polymorphic proteins. Some variants are associated with increased sensitivity to toxic compounds, as it is known for the GSTM1-null variant allele. However, the influence of the GSTM1 allele variant genotype on GSTM1-mRNA quantity in oral squamous cell carcinoma (OSCC) and normal mucosa as well as the impact on prognosis remains unclear. The genotype for GSTM1 (mutation vs. wild type) was determined by polymerase chain reaction (PCR) using genomic DNA extracted from peripheral blood from 28 OSCC patients. From the same patients, 28 pairs of OSCC cells and normal oral mucosal cells were obtained by brush biopsy. mRNA was extracted from these paired samples and the expression levels of GSTM1 were examined by real-time reverse transcriptase qPCR (RT-qPCR). The mRNA expression of the OSCC samples was normalized against an external standard, as well as to the corresponding normal mucosa. The coincidence of GSTM1 genotype and GSTM1-mRNA-expression level was examined. In 15 patients (54%), the null genotype GSTM1 was present. In the GSTM1-null allele group, the GSTM1 gene expression level was determined at 1.63 (mean: 3.08; SD 3.4) folds vs. 3.6 (mean: 10.5; SD 14.2) folds in the group with the positive genotype (p=0.06), if calibrated vs. individual normal mucosa. More T3 and T4 OSCCs (+38%), higher UICC stadia (+38%) and more lymphatic metastasis (+28%) were seen in the group with the negative allele. Furthermore, positive GSTM1 genotype and enhanced GSTM1 gene expression was accompanied with increased tumor size, lymphatic metastasis status and UICC stadium. A coincidence of null type GSTM1 and lowered GSTM1 gene expression was observed. The larger tumors and more frequent lymph node metastases in this group could be explained by the insufficient cell protection by GST.

OBJECTIVE

To investigate the association between glutathione S-transferase (GST) gene polymorphisms and sudden sensorineural hearing loss (SSNHL) in a population of consecutive Italian patients. Assuming that reactive oxygen species formation may play a role in inner ear damage, we investigated whether profiles of GSTs antioxidant enzymes M1 and T1 genotypes may be associated with the risk of SSNHL.

METHODS

A prospective study in patients with SSNHL.

METHODS

We investigated 80 Italian patients with SSNHL for the frequency of GSTT1 and GSTM1 polymorphisms. Genotype distribution of all factors found in patients were compared with those of 80 healthy control subjects of the same ethnic background using chi and odds-ratio analysis. Statistical significance was accepted at a level of p < 0.05.

RESULTS

In our series, the frequencies of GSTM1 and GSTT1 null genotypes did not differ from those of the control subjects.

CONCLUSIONS

The few studies regarding genetic polymorphisms of GSTs in SSNHL are not conclusive. Further studies are needed to investigate the role of antioxidants including GSTs in SSNHL and to provide the lacking information to improve our knowledge in the field before implementing the use of genetic polymorphism in the SSNHL medicine daily practice.

Glutathione-S-transferase genes (GSTs) encode enzymes that are involved in detoxification and neutralization of reactive oxygen species (ROS) in male reproductive system and play protective role during spermatogenesis. The aim of the study was to evaluate whether C/G missense mutation (rs135955605) within glutathione-S-transferase M1 (GSTM1) gene is associated with selected parameters of frozen-thawed semen in 309 Holstein-Friesian bulls. Single nucleotide substitution C/G was identified by amplification of GSTM1 gene fragment followed be digestion with restriction enzyme DdeI. Bulls with GG genotype were the most frequent (67.96%), in comparison to CC (2.59%) and GC (29.45%). Significant associations were found between GSTM1 genotypes and ATP content and total sperm motility. Bulls with GG genotype had the highest values for both traits. Rare variant C of GSTM1 was associated with significant decrease of sperm motility and ATP content. Our results demonstrate that C/G missense mutation within GSTM1 gene is involved in bull sperm quality.

The standard paradigm providing a general mechanistic explanation for the association of cumulative, excessive oestrogen exposure and breast cancer risk is that the proliferative stimulus provided by 17 beta-estradiol (E2) leads to the appearance of spontaneous mutations. Thus, the key contribution of E2 is the stimulation of breast epithelial cell proliferation. However, mounting evidence supports a complimentary pathway involving direct (oestrogen-quinone DNA adducts) and indirect (oxidative DNA damage via redox cycling) genotoxicity originating from oestrogen metabolites. While mutations in high penetrance genes such as BRCA1, BRCA2 and p53 confer a high risk for an individual, they represent a low overall attributable risk due to low allele frequencies in the population. On the other hand, mutations in phases I and II enzyme genes involved in xenobiotic and endobiotic metabolism, including genes encoding CYP1A1, N-acetyltransferase 2 and glutathione-S-transferase (GST) isoforms M1 (null), T1 (null), and P1 (low-activity allele), might confer a low relative cancer risk for an individual. However, because these mutations seem to be common among individuals, they represent a high attributable risk category of genes. The intent of this review is to examine current literature on the molecular epidemiology of breast cancer with emphasis on the role of polymorphisms in high and low penetrance genes on susceptibility to breast cancer.

OBJECTIVE

The objective of this study was to examine the association between glutathione s-transferase M1, T1 genotype and the risk of gastric cancer.

METHODS

A case-control study was carried out and polymerase chain reaction (PCR) technique was used to identify GST M1, GST T1 genotype in 95 cases of primary gastric cancer and 94 controls.

RESULTS

The frequency of GST M1 null genotype was 63.16% and 45.74%, respectively in gastric cancer cases and control group, with statistically significant difference (chi(2) = 5.75, P = 0.0165). GST M1 null genotype correlated with the susceptibility to gastric cancer (OR = 2.03, 95% CI of OR = 1.09 - 3.80). The risk for gastric cancer in those with GST M1 null and GST T1 non-null genotype was significantly higher than that in those with GST M1 non-null and GST T1 null genotype, with an OR of 2.91 and 95% CI of ORs 1.09 - 7.89. The risk for gastric cancer in those smoking with GST M1 null genotype increased significantly (OR = 8.06, 95% CI of OR = 2.83 - 23.67).

CONCLUSIONS

GST M1 null genotype was associated with the risk for gastric cancer.

Azathioprine has been clinically used for decades in connection with organ transplantation, autoimmune disease, and treatment of cancer. Toxic side-reactions are common and have been linked to the liberation of excessively high concentrations of 6-mercaptopurine and corresponding toxic metabolites. An allelic variant of thiopurine methyltransferase with low activity is associated with elevated concentrations of 6-mercaptopurine. However, other genetic markers remain to be identified in order to fully account for adverse reactions and efficacy failure. In the present study, we studied the five known allelic variants of human glutathione transferase A2-2 (GST A2-2) (EC 2.5.1.18), abundantly expressed in liver and efficiently catalyzing the bioactivation of azathioprine to release 6-mercaptopurine. All five variants exhibited high activity with azathioprine, but allelic variant E of GST A2-2 displayed a 3-4-fold elevated catalytic efficiency compared to the other variants. High GST activity can lead to overproduction of 6-mercaptopurine, and the nature of the multiple forms of GSTs in a patient will obviously affect the metabolism of azathioprine. In addition to GST A2-2, the polymorphic GST M1-1 is also highly active with azathioprine. Considering our findings, it appears that the genotypic and phenotypic variations in the GST complement may influence the presentation of adverse reactions in patients treated with azathioprine. Clinical trials will be required to clarify the impact of the GST expression in comparison with the established biomarker thiopurine methyltransferase as predictors of adverse reactions.

BACKGROUND

The super family of glutathione S-transferases (GSTs) is composed of multiple isoenzymes with significant evidence of functional polymorphic variation. GSTs detoxify potentially mutagenic and toxic DNA-reactive electrophiles, including metabolites of several chemotherapeutic agents, some of which are suspected human carcinogens. Polymorphisms within the phase II metabolizer enzymes GST T1, GST M1, and GST P1 affect the body's ability to detoxify a range of potential leukemogens encountered in the environment.

OBJECTIVE

To address how differences in the human GST isoenzyme expression patterns influence cancer susceptibility, prognosis, and treatment.

METHODS

A total of 50 patients with acute myeloid leukemia (AML), as well as 50 age and sex matched apparently healthy volunteers were genotyped for GSTP 1, GSTM 1, and GSTT 1 gene polymorphisms using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and conventional polymerase chain reaction (PCR), respectively.

RESULTS

For GSTP1 313 A → G (GSTP1 Ile105Val) polymorphism, It was found that the wild genotype (AA) was significantly higher among control subjects (P value = 0.0277), while the frequency of heteromutant genotype (AG) and mutant G allele (AG + GG) was significantly higher among patients (P value = 0.0402, P value = 0.0277, respectively). For GSTM1 and GSTT1gene, we found statistically significantly higher frequency among patients regarding homozygous gene deletion (P value = 0.0005).

CONCLUSIONS

We demonstrated that GSTM1 null or GSTT1 null genotypes may be considered independent risk factors for AML with no impact on prognosis and GSTP1 * 105 genotype is a prognostic factor, adding independent information to the routine laboratory parameters and cytogenetic and molecular alterations of the tumor cells.