Genetic polymorphisms of human cytosol glutathione S-transferases and prostate cancer

Association of GSTM1, GSTT1, and GSTP1 Ile105Val polymorphisms with risk of age-related macular degeneration: a meta-analysis

BACKGROUND

This study determined to evaluate the association between glutathione S-transferase (GST) polymorphisms, namely, GSTM1 (rs1183423000, presence/absence), GSTT1 (rs1601993659, presence/absence), and GSTP1 Ile105Val (rs1695, A>G) polymorphisms, and AMD risk.

METHODS

We searched PubMed, Embase, and Web of Science databases from January 2000 to June 2021. The odds ratio (OR) and 95% confidence interval (95% CI) were used as effect sizes. Heterogeneity was assessed using the heterogeneity metric I².

RESULTS

Five relevant studies involving 875 patients with AMD and 966 healthy controls were included in this meta-analysis, four studies concerning GSTM1 null polymorphism, four studies regarding GSTT1 null polymorphism, and four studies on GSTP1 Ile105Val polymorphism. The GSTM1 null polymorphism, GSTT1 null polymorphism and GSTP1 Ile105Val polymorphism were not significantly associated with AMD risk (OR 1.13, 95% CI 0.73-1.75, p = 0.59; OR 1.05, 95% CI 0.81-1.36, p = 0.69; OR 1.20, 95% CI 0.97-1.47, p = 0.09, respectively). There was no association between the combined GSTM1 null genotype and GSTT1 null genotype and AMD risk (OR 1.16, 95% CI 0.42-3.17, p = 0.77). Subgroup analyses revealed that the GSTM1 null genotype was associated with an increased risk of AMD in the Turkish population (OR 1.67, 95% CI 1.13-2.47, p = 0.01) and the GSTM1 null genotype was associated with a decreased incidence of non-exudative AMD (OR 0.72, 95% CI 0.52-0.99, p = 0.01). There was no obvious risk of publication bias found.

CONCLUSIONS

This meta-analysis indicated that there were no significant associations between GSTM1, GSTT1, and GSTP1 Ile105Val polymorphisms and AMD risk.

Glutathione-S-transferases genes-promising predictors of hepatic dysfunction

One of the most commonly known genes involved in chronic diffuse liver diseases pathogenesis are genes that encodes the synthesis of glutathione-S-transferase (GST), known as the second phase enzyme detoxification system that protects against endogenous oxidative stress and exogenous toxins, through catalisation of glutathione sulfuric groups conjugation and decontamination of lipid and deoxyribonucleic acid oxidation products. The group of GST enzymes consists of cytosolic, mitochondrial and microsomal fractions. Recently, eight classes of soluble cytoplasmic isoforms of GST enzymes are widely known: α-, ζ-, θ-, κ-, μ-, π-, σ-, and ω-. The GSTs gene family in the Human Gene Nomenclature Committee, online database recorded over 20 functional genes. The level of GSTs expression is considered to be a crucial factor in determining the sensitivity of cells to a broad spectrum of toxins. Nevertheless, human GSTs genes have multiple and frequent polymorphisms that include the complete absence of the GSTM1 or the GSTT1 gene. Current review supports the position that genetic polymorphism of GST genes is involved in the pathogenesis of various liver diseases, particularly non-alcoholic fatty liver disease, hepatitis and liver cirrhosis of different etiology and hepatocellular carcinoma. Certain GST allelic variants were proven to be associated with susceptibility to hepatological pathology, and correlations with the natural course of the diseases were subsequently postulated.

Metabolic pathways in sporadic colorectal carcinogenesis: A new proposal

Given the reports made about geographical differences in Colorectal Cancer (CRC) occurrence, suggesting a link between dietary habits, genes and cancer risk, we hypothesise that there are four fundamental metabolic pathways involved in diet-genes interactions, directly implicated in colorectal carcinogenesis: folate metabolism; lipid metabolism; oxidative stress response; and inflammatory response. Supporting this hypothesis are the evidence given by the significant associations between several diet-genes polymorphisms and CRC, namely: MTHFR, MTR, MTRR and TS (involved in folate metabolism); NPY, APOA1, APOB, APOC3, APOE, CETP, LPL and PON1 (involved in lipid metabolism); MNSOD, SOD3, CAT, GSTP1, GSTT1 and GSTM1 (involved in oxidative stress response); and IL-1, IL-6, TNF-α, and TGF-β (involved in inflammatory response). We also highlight the association between some foods/nutrients/nutraceuticals that are important in CRC prevention or treatment and the four metabolic pathways proposed, and the recent results of genome-wide association studies, both assisting our hypothesis. Finally, we propose a new line of investigation with larger studies, using accurate dietary biomarkers and investigating the four metabolic pathways genes simultaneously. This line of investigation will be essential to understand the full complexity of the association between nature and nurture in CRC and perhaps in other types of cancers. Only with this in-depth knowledge will it be possible to make personalised nutrition recommendations for disease prevention and management.

Association of Glutathione S-Transferase theta 1 and mu 1 Genes Polymorphisms with the Susceptibility of Myocardial Infarction in Bangladesh

Background

Myocardial infarction is one of the leading causes of morbidity and mortality worldwide. Oxidative stress plays a vital role in the pathogenesis of atherosclerosis leading to myocardial infarction and Glutathione S-transferases (GSTs) act as detoxifying enzymes to reduce oxidative stress. The aim of the present study was to investigate the associations of the GST (T1 & M1) gene polymorphism with the susceptibility of myocardial infarction in the Bangladeshi population.

Methods

A case-control study on 100 cardiac patients with MI and 150 control subjects was conducted. The genotyping of GST (T1 & M1) gene was done using conventional Polymerase Chain Reaction.

Results

The percentage of GSTM1 genotypes was significantly (p< 0.01) lower in patients compared to control subjects while the GSTT1 genotypes were not significantly different between the study subjects. The individual with GSTM1 null allele was at 2.5-fold increased risk {odds ratio (OR)= 2.5; 95 % confidence interval (95 % CI)= 1.4 to 4.3; p< 0.01} of experiencing MI while individual with either GSTM1 or GSTT1 genotypes was at lower risk. In the case of GST M1 and GST T1 combined genotype, patients having both null genotypes for GST M1 and GST T1 gene showed significantly (p< 0.01) higher risk of experiencing MI when compared to control subjects (OR= 3.5; 95% CI= 1.7-7.2; p< 0.001).

Conclusion

Thus our recent study suggested that GSTM1 alone and GSTM1 and T1 in combination augments the risk of MI in Bangladeshi population.

GSTM1 and GSTT1 Polymorphisms and Susceptibility to Prostate Cancer: A Case-Control Study of the Algerian Population

Objective: Prostate cancer (PCa) is a major public health problem worldwide, with high morbidity and mortality levels. Advanced age, androgen stimulation, and ethnicity have been reported to be possible risk factors. It has been suggested that particular genetic polymorphisms in glutathione S-transferases (GST), xenobiotic-metabolising enzymes, could predispose to prostate cancer through heritable deficiency in detoxification of environmental carcinogens. Conflicts in the published results and the absence of similar in depth studies in Algeria prompted us to perform the present case-control study of GSTM1 and GSTT1 polymorphisms and their possible association with PCa in an Algerian population. Methods: We determined GSTM1 and GSTT1 genotypes for 49 histologically verified prostate cancer patients and in 41 age-matched healthy controls by multiplex polymerase chain reaction (PCR) using peripheral blood DNA samples. Result: While an association between the GSTM1 null genotype and PCa risk (OR= 3.69, 95% CI= 1.30-10.44; P = 0.01) was evident, the GSTT1 null genotype (OR= 0.92, 95% IC= 0.32-2.62; P = 0.49) appeared without influence. Furthermore, no statistically significant differences between the double null genotype and PCa is detected, also no statistically significant differences between smoking status and PCa is detected. Conclusion: The GSTM1 null genotype may increase individual susceptibility to prostate cancer. On the other hand, the null-activity genotype of GSTT1 did not appear to contribute to the risk of prostate cancer in our population.

WOMEN IN CANCER THEMATIC REVIEW: Diverse functions of DNA methylation: implications for prostate cancer and beyond

Prostate cancer is one of the most common malignancies in men worldwide. Current clinical screening ensures that most prostate cancers are diagnosed while still organ confined, but disease outcome is highly variable. Thus, a better understanding of the molecular features contributing to prostate cancer aggressiveness is being sought. For many cancers, aberrant genome-wide patterns of cytosine DNA methylation in CpG dinucleotides distinguish tumor from normal tissue and contribute to disease progression by altering the transcriptome. In prostate cancer, recent genomic studies identified cancer and high grade-specific differential DNA methylation in gene promoters, gene bodies, gene 3' ends and at distal regulatory elements. Using examples from developmental and disease systems, we will discuss how DNA methylation in each of these genomic contexts can contribute to transcriptome diversity by modulating transcription initiation, alternative transcription start site selection, alternative pre-mRNA splicing and alternative polyadenylation. Alternative transcripts from the same gene often exhibit altered protein-coding potential, translatability, stability and/or localization. All of these can have functional consequences in cells. In future work, it will be important to determine if DNA methylation abnormalities in prostate cancer modify the transcriptome through some or all of these mechanisms and if these DNA methylation-mediated transcriptome alterations impact prostate tumorigenesis and aggressiveness.

Genetic Polymorphisms of Cytochrome P4501A1 (CYP1A1) and Glutathione S-Transferase P1 (GSTP1) and Risk of Hepatocellular Carcinoma Among Chronic Hepatitis C Patients in Egypt

Cytochrome P450 1A1 (CYP1A1) and Glutathione S-transferase P1 (GSTP1) genes are involved in the metabolism of many carcinogens. Polymorphisms in these genes with altered enzyme activity have been reported. The present study evaluated the synergistic effect between CYP1A1 and GSTP1 gene polymorphisms and smoking on development of HCV-related liver disease and hepatocellular carcinoma (HCC). The patients group comprised 40 patients with HCC and 40 patients with liver cirrhosis. The control group comprised 40 healthy subjects having no history of malignancy. The genetic polymorphisms were studied using polymerase chain reaction restriction fragment length polymorphism (PCR RFLP) technique on blood samples. The number of current or former smoker among HCC and cirrhotic patients as well as the median Pack/year of cigarette smoked were significantly higher in HCC and liver cirrhotic patients than in control group. Subjects with CYP1A1 gene variants (m1 and m3) had no significant risk to develop cirrhosis or HCC compared to control group. Individuals carrying the Ile/Val genotype of GSTP1 had a significant increased risk of HCC (OR of 2.2, 95 % CI 1.143-4.261) and had larger tumor size. No significant risk was observed on combining both genes variants or on combining smoking with variants of both genes. In conclusion, the GSTP1 Ile/Val genotype and Val allele are associated with an increased risk of HCC. CYP1A1 and GSTP1 genes variants interaction did not increase the risk of HCC.

Association of GSTT1 and GSTM1 gene polymorphisms with coronary artery disease in North Indian Punjabi population: a case-control study

BACKGROUND

Glutathione S-transferases are metabolic enzymes which are responsible for detoxification of endogenous (products of oxidative stress) as well as exogenous (drugs, pesticides, herbicides, environmental pollutants and carcinogens) products. Dysfunctional detoxification enzymes are responsible for the production of oxidative stress; a major contributor to the development of coronary artery disease (CAD).

OBJECTIVES

The present case-control study aimed to investigate the association of GSTT1 and GSTM1 gene polymorphisms with CAD.

METHODS

In the present study, 200 patients diagnosed with CAD and 200 age, sex and population subgroup matched healthy controls were enrolled. The GSTT1 and GSTM1 gene polymorphisms were examined using multiplex PCR.

RESULTS

The frequency of GSTT1 null genotype was significantly (p=0.038) lower in patients with CAD (6.00%) than in controls (12.50%). The GSTT1 null genotype showed protection against CAD (OR=0.45, 95% CI 0.22 to 0.92, p=0.028). The frequency of GSTM1 null genotype was significantly (p=0.004) higher in patients (31%) compared with controls (18%). The GSTM1 null genotype conferred twofold increased risk of developing CAD (OR=2.05, 95% CI 1.28 to 3.27, p=0.003).

CONCLUSIONS

The results concluded that the GSTT1 null genotype showed protection against CAD while the GSTM1 null genotype might be involved in the pathogenesis and development of CAD.

The Association between Gene-Environment Interactions and Diseases Involving the Human GST Superfamily with SNP Variants

Exposure to environmental hazards has been associated with diseases in humans. The identification of single nucleotide polymorphisms (SNPs) in human populations exposed to different environmental hazards, is vital for detecting the genetic risks of some important human diseases. Several studies in this field have been conducted on glutathione S-transferases (GSTs), a phase II detoxification superfamily, to investigate its role in the occurrence of diseases. Human GSTs consist of cytosolic and microsomal superfamilies that are further divided into subfamilies. Based on scientific search engines and a review of the literature, we have found a large amount of published articles on human GST super- and subfamilies that have greatly assisted in our efforts to examine their role in health and disease. Because of its polymorphic variations in relation to environmental hazards such as air pollutants, cigarette smoke, pesticides, heavy metals, carcinogens, pharmaceutical drugs, and xenobiotics, GST is considered as a significant biomarker. This review examines the studies on gene-environment interactions related to various diseases with respect to single nucleotide polymorphisms (SNPs) found in the GST superfamily. Overall, it can be concluded that interactions between GST genes and environmental factors play an important role in human diseases.

Influence of GSTM1, GSTT1, and GSTP1 Polymorphisms on Type 2 Diabetes Mellitus and Diabetic Sensorimotor Peripheral Neuropathy Risk

BACKGROUND AND AIMS

Diabetic neuropathy is a frequent complication of type 2 diabetes mellitus (T2DM). Genetic susceptibility and oxidative stress may play a role in the appearance of T2DM and diabetic neuropathy. We investigated the relation between polymorphism in genes related to oxidative stress such as GSTM1, GSTT1, and GSTP1 and the presence of T2DM and diabetic neuropathy (DN).

METHODS

Samples were collected from 84 patients with T2DM (42 patients with DN and 42 patients without DN) and 98 healthy controls and genotyped by using polymerase chain reaction and restriction fragment length polymorphism method.

RESULTS

GSTP1 Ile105Val polymorphism was associated with the risk of developing T2DM (p = 0.05) but not with the risk of developing DN in diabetic cases. GSTM1 and GSTT1 gene polymorphisms were associated with neither the risk of developing T2DM nor the risk of DN occurrence in diabetic patients. No association was observed between the patients with T2DM and DSPN (diabetic sensorimotor peripheral neuropathy) and T2DM without DSPN regarding investigated polymorphism.

CONCLUSION

Our data suggest that GSTP1 gene polymorphisms may contribute to the development of T2DM in Romanian population. GSTM1, GSTT1, and GSTP1 gene polymorphisms are not associated with susceptibility of developing diabetic neuropathy in T2DM patients.

Association of glutathione S-transferase pi (GSTP1) Ile105Val polymorphism with the risk of skin cancer: a meta-analysis

Numerous epidemiological studies have evaluated the association of Glutathione S-transferase P1 (GSTP1) Ile105Val polymorphism with the risk of skin cancer. However, the results remain inconclusive. To derive a more precise estimation of the association between the GSTP1 Ile105Val polymorphism and skin cancer risk, a meta-analysis was performed. A comprehensive search was conducted to identify the eligible studies. We used odds ratios (ORs) with 95 % confidence intervals (CIs) to assess the association of GSTP1 Ile105Val polymorphism with skin cancer risk. Thirteen case-control studies in nine articles, which included a total of 1504 cases and 2243 controls. Overall, we found that GSTP1 Ile105Val polymorphism was not associated with skin cancer risk. Furthermore, subgroup analysis by histological types showed that GSTP1 Ile105Val polymorphism was associated with risks of malignant melanoma under the dominant model (Val/Val + Val/Ile vs. Ile/Ile: OR 1.230, 95 % CI 1.017-1.488, P = 0.033). However, lack of association between GSTP1 Ile105Val polymorphism and BCC and SCC risk in all genetic models. Our meta-analysis suggested that the GSTP1 Ile105Val polymorphism might be associated with increased risk of malignant melanoma in Caucasian population.

Biotransformation of xenobiotics in the human colon and rectum and its association with colorectal cancer

In humans, the liver is generally considered to be the major organ contributing to drug metabolism, but studies during the last years have suggested an important role of the extra-hepatic drug metabolism. The gastrointestinal tract (GI-tract) is the major path of entry for a wide variety of compounds including food, and orally administered drugs, but also compounds - with neither nutrient nor other functional value - such as carcinogens. These compounds are metabolized by a large number of enzymes, including the cytochrome P450 (CYP), the glutathione S-transferase (GST) family, the uridine 5'-diphospho- glucuronosyltransferase (UDP-glucuronosyltransferase - UGT) superfamily, alcohol-metabolizing enzymes, sulfotransferases, etc. These enzymes can either inactivate carcinogens or, in some cases, generate reactive species with higher reactivity compared to the original compound. Most data in this field of research originate from animal or in vitro studies, wherein human studies are limited. Here, we review the human studies, in particular the studies on the phenotypic expression of these enzymes in the colon and rectum to get an impression of the actual enzyme levels in this primary organ of exposure. The aim of this review is to give a summary of currently available data on the relation between the CYP, the GST and the UGT biotransformation system and colorectal cancer obtained from clinical and epidemiological studies in humans.

Can pharmacogenetics explain efficacy and safety of cisplatin pharmacotherapy?

Several recent pharmacogenetic studies have investigated the variability in both outcome and toxicity in cisplatin-based therapies. These studies have focused on the genetic variability of therapeutic targets that could affect cisplatin response and toxicity in diverse type of cancer including lung, gastric, ovarian, testicular, and esophageal cancer. In this review, we seek to update the reader in this area of investigation, focusing primarily on DNA reparation enzymes and cisplatin metabolism through Glutathione S-Transferases (GSTs). Current evidence indicates a potential application of pharmacogenetics in therapeutic schemes in which cisplatin is the cornerstone of these treatments. Therefore, a collaborative effort is required to study these molecular characteristics in order to generate a genetic panel with clinical utility.

GSTT1 polymorphism and the risk of developing prostate cancer

A possible association between glutathione S-transferase theta 1 gene (GSTT1) polymorphism and the risk of developing prostate cancer is currently hotly debated, but evidence from various epidemiologic studies remains unclear. This investigation was performed to assess whether an association between GSTT1 polymorphism and prostate cancer risk exists by using meta-analysis to combine comparable studies, thereby increasing sample size and statistical significance, as well as to identify patterns in various studies. The association reports were identified from the PubMed database and the Cochrane Library on March 1, 2013, and data from eligible studies (from 1999-2012) were synthesized. Thirty-eight reports were included in this meta-analysis on the association of the null genotype of GSTT1 with prostate cancer risk. No solid association between the GSTT1 null genotype and prostate cancer risk could be established for the overall population (odds ratio = 1.11, 95% confidence interval: 0.97, 1.27; P = 0.13). However, the GSTT1 null genotype was distinctly associated with prostate cancer risk in Caucasians (odds ratio = 1.24, 95% confidence interval: 1.03, 1.48, P = 0.02). In conclusion, the GSTT1 null genotype is associated with prostate cancer risk in Caucasians, but not in the overall population.

Genetic polymorphism of glutathione S-transferase P1 (GSTP1) in Delhi population and comparison with other global populations

Glutathione S-transferases (GSTs) belong to a super family of phase II detoxification enzymes, which play an important role in protecting cells from damage caused by endogenous and exogenous compounds by conjugating reactive intermediates with glutathione to produce less reactive water-soluble compounds. In the present study, we determined the frequencies of two polymorphisms in exon 5 and exon 6 of GSTP1 gene in 500 normal individuals from Delhi. GSTP1 polymorphism was analysed by PCR-RFLP using amplification refractory mutation system (ARMS) assay. Two polymorphic sites in GSTP1 (Ile105 → Val105; Ala114 → Val114) have been analysed simultaneously, which results in four alleles: GSTP1*A (wild-type Ile105; Ala114), GSTP1*B (Val105; Ala114), GSTP1*C (Val105; Val114) and GSTP1*D (Ile105; Val114). The GSTP1 allele frequency in Delhi population was 0.663, 0.248, 0.069, and 0.020 for GSTP1*A, GSTP1*B, GSTP1*C, and GSTP1*D respectively. The frequency of Ile105 and Val105 allele was 0.683 and 0.317 respectively and it was calculated for the purpose of comparison with published data where all the four alleles were not analysed. GSTP1 alleles from Delhi population were compared with reported frequencies from all over India, and from other ethnic groups worldwide. This study would provide a basic database for future genetic studies.

Trichloroethylene: Mechanistic, epidemiologic and other supporting evidence of carcinogenic hazard

The chlorinated solvent trichloroethylene (TCE) is a ubiquitous environmental pollutant. The carcinogenic hazard of TCE was the subject of a 2012 evaluation by a Working Group of the International Agency for Research on Cancer (IARC). Information on exposures, relevant data from epidemiologic studies, bioassays in experimental animals, and toxicity and mechanism of action studies was used to conclude that TCE is carcinogenic to humans (Group 1). This article summarizes the key evidence forming the scientific bases for the IARC classification. Exposure to TCE from environmental sources (including hazardous waste sites and contaminated water) is common throughout the world. While workplace use of TCE has been declining, occupational exposures remain of concern, especially in developing countries. The strongest human evidence is from studies of occupational TCE exposure and kidney cancer. Positive, although less consistent, associations were reported for liver cancer and non-Hodgkin lymphoma. TCE is carcinogenic at multiple sites in multiple species and strains of experimental animals. The mechanistic evidence includes extensive data on the toxicokinetics and genotoxicity of TCE and its metabolites. Together, available evidence provided a cohesive database supporting the human cancer hazard of TCE, particularly in the kidney. For other target sites of carcinogenicity, mechanistic and other data were found to be more limited. Important sources of susceptibility to TCE toxicity and carcinogenicity were also reviewed by the Working Group. In all, consideration of the multiple evidence streams presented herein informed the IARC conclusions regarding the carcinogenicity of TCE.

GSTP1 Ile105Val polymorphism and prostate cancer risk: evidence from a meta-analysis

BACKGROUND

Glutathione S-transferase P1 (GSTP1) is thought to be involved in the detoxification of reactive carcinogen metabolites. Numerous epidemiological studies have evaluated the association of GSTP1 Ile105Val polymorphism with the risk of prostate cancer. However, the results remain inconclusive. To derive a more precise estimation, a meta-analysis was performed.

METHODOLOGY/PRINCIPAL FINDINGS

A comprehensive search was conducted to identify the eligible studies. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the relationship. The overall association was not significant (Val/Val vs. Ile/Ile OR = 1.06, 95% CI = 0.90-1.25, P = 0.50; Val/Val vs. Val/Ile+Ile/Ile: OR = 1.07, 95% CI = 0.91-1.25, P = 0.44). In subgroup analyses by ethnicity and prostate cancer grade, the similar results were observed. However, in stratified analysis by clinical stage, we found a significant association with low-stage prostate cancer (Val/Val vs. Ile/Ile: OR = 2.70, 95% CI = 1.73-4.22, P<0.001; Val/Val vs. Val/Ile+Ile/Ile: OR = 2.14, 95% CI = 1.38-3.33, P = 0.001). Moreover, there was no statistically significant evidence of multiplicative interactions neither between the GSTP1 Ile105Val polymorphism and GSTM1, nor between smoking status and GSTP1 on prostate cancer risk.

CONCLUSIONS

This meta-analysis showed that GSTP1 Ile105Val polymorphism might not be significantly associated with overall prostate cancer risk. Further stratified analyses showed a significant association with low-stage prostate cancer.

Significant association of Glutathione S-transferase T1 null genotype with prostate cancer risk: a meta-analysis of 26,393 subjects

Background

Recent studies on the association between Glutathione S-transferase T1 (GSTT1) polymorphism and risk of prostate cancer showed inconclusive results. To clarify this possible association, we conducted a meta-analysis of published studies.

Methods

Data were collected from the following electronic databases: Pubmed, Embase, and Chinese Biomedical Database (CBM). The odds ratio (OR) and its 95% confidence interval (95%CI) was used to assess the strength of the association. We summarized the data on the association between GSTT1 null genotype and risk of prostate cancer in the overall population, and performed subgroup analyses by ethnicity, adjusted ORs, and types of controls.

Results

Ultimately, a total of 43 studies with a total of 26,393 subjects (9,934 cases and 16,459 controls) were eligible for meta-analysis. Overall, there was a significant association between GSTT1 null genotype and increased risk of prostate cancer (OR = 1.14, 95%CI 1.01–1.29, P = 0.034). Meta-analysis of adjusted ORs also showed a significant association between GSTT1 null genotype and increased risk of prostate cancer (OR = 1.34, 95%CI 1.09–1.64, P = 0.006). Similar results were found in the subgroup analyses by ethnicity and types of controls.

Conclusion

This meta-analysis demonstrates that GSTT1 null genotype is associated with prostate cancer susceptibility, and GSTT1 null genotype contributes to increased risk of prostate cancer.

Glutathione S-transferase P1 correlated with oxidative stress in hepatocellular carcinoma

BACKGROUND

Glutathione-S-transferase P1 (GSTP1) is an important phase II enzyme that can protect cells from oxidative stress in various human cancers. However, few clinical studies were undertaken on the relationship between GSTP1 and oxidative stress in hepatocellular carcinoma (HCC). The present study was therefore aimed to evaluate the potential associations between GSTP1 and oxidative stress in HCC patients.

METHODS

The GSTP1 expression in peripheral blood mononuclear cells (PBMCs) was determined by flow cytometry from 38 HCC patients and 38 chronic hepatitis B (CHB) patients. The GSTP1 mRNA level in PBMCs was determined by real-time quantitative polymerase chain reaction. Enzyme-linked-immunosorbent-assay (ELISA) was performed to measure the oxidative stress status, including plasma levels of malondialdehyde (MDA), xanthine oxidase (XOD), reduced glutathione hormone (GSH) and glutathione-S-transferases (GST).

RESULTS

Significantly decreased GSTP1 protein expression was found in HCC patients than in CHB patients (P<0.05). The GSTP1 mRNA expression of HCC patients was also decreased compared with CHB patients (P<0.05). MDA and XOD levels were significantly higher in HCC patients than in CHB patients, while plasma GSH and GST levels were statistically lower in HCC patients than in CHB patients. GSTP1 expression level was correlated with plasma levels of MDA (P<0.01), XOD (P = 0.01) and GSH (P< 0.01), GST (P< 0.01).

CONCLUSION

We demonstrated that the reduced GSTP1 expression might contribute to oxidative stress in the development of HCC from CHB.

Role of pharmacogenetics in busulfan/cyclophosphamide conditioning therapy prior to hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is a curative treatment for several malignant and nonmalignant disorders. Busulfan (Bu) and cyclophosphamide (Cy) are the most commonly used alkylators in high-dose pretransplant conditioning for HSCT; a treatment that is correlated with drug-related toxicity and relapse. Pharmacogenetic investigations have shown that CYP450, as well as aldehyde dehydrogenase, are clearly involved with Cy metabolism and are associated with altered treatment response, Cy metabolism and the unique stem-cell sparing capacity. Moreover, glutathione-S-transferase isoenzymes have been associated with cellular outward transport of various alkylating agents, including Cy metabolites, melphalan, Bu and chlorambucil. A shift from genetic-based studies to whole-genome-based investigations of Cy- and Bu-associated markers may contribute to personalizing the conditioning therapy and enhancing the clinical outcome of HSCT.

Significant association of glutathione S-transferase T1 null genotype with esophageal cancer risk: a meta-analysis

Recent studies on the association between glutathione S-transferase T1 (GSTT1) polymorphism and risk of esophageal cancer showed inconclusive results. To clarify this possible association, we conducted a meta-analysis of published studies. Data were collected from the following electronic databases: Pubmed, Embase, and Chinese Biomedical Database (CBM). The odds ratio (OR) and its 95 % confidence interval (95 % CI) was used to assess the strength of this association. We summarized the data on the association between GSTT1 null genotype and risk of esophageal cancer in the overall population, and performed subgroup analyses by ethnicity. Finally, a total of 24 independent studies including a total of 7,801 subjects (2,965 cases and 4,836 controls) were eligible for meta-analysis. In the overall analysis, there was no significant association between GSTT1 null genotype and esophageal cancer risk (OR = 1.15, 95 % CI 0.99-1.33, P = 0.067). However, meta-analysis of adjusted ORs showed a significant association between GSTT1 null genotype and increased risk of esophageal cancer (OR = 1.30, 95 % CI 1.08-1.56, P = 0.005). Subgroup analyses by ethnicity showed there was an obvious association between GSTT1 null genotype and increased risk of esophageal cancer in East Asians (OR = 1.24, 95 % CI 1.10-1.39, P < 0.001), but not in Caucasians (OR = 0.89, 95 % CI 0.71-1.11, P = 0.300). There was no obvious risk of publication bias in this meta-analysis (Egger's test, P = 0.784). This meta-analysis demonstrates that GSTT1 null genotype is independently associated with increased risk of esophageal cancer, and a race-specific effect may exist in this association.

Association of GSTM1 null allele with prostate cancer risk: evidence from 36 case-control studies

BACKGROUND

Glutathione S-transferase M1 (GSTM1) is thought to be involved in detoxifying several carcinogens and may play a vital role in tumorigenesis. Numerous studies have evaluated the association between GSTM1 null/present polymorphism and risk of prostate cancer (PCa). However, the results remain inconsistent. To derive a more precise estimation, we performed a meta-analysis.

METHODOLOGY/PRINCIPAL FINDINGS

A comprehensive search was conducted to identify all eligible case-control studies. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. The overall association was significant (OR = 1.28, 95% CI: 1.11-1.48, P = 0.001). Moreover, subgroup analyses showed GSTM1 null genotype significantly associated with PCa risk among Asians (OR = 1.35, 95% CI: 1.03-1.78, P = 0.03) but not among Caucasians (OR = 1.12, 95% CI: 0.96-1.31, P = 0.16). In addition, we did not find that smoking modified the genotype effect on the risk of PCa.

CONCLUSIONS/SIGNIFICANCE

The present meta-analysis suggested that GSTM1 null allele was a low-penetrant risk factor for PCa among Asians.

GSTM1 polymorphism in patients with primary open-angle glaucoma

Primary open-angle glaucoma (POAG) is characterized by loss of retinal ganglion cells, optic nerve damage and irreversible loss of visual field. Glaucoma is the second leading cause of blindness worldwide. It was estimated that in 2010 there were about 60.5 million glaucoma cases worldwide; among these patients, 4.5 million will become bilaterally blind. Glutathione S-transferases (GST) are a group of drug-metabolizing enzymes of phase-II that act in the detoxification of xenobiotics and inactivate end-products formed as secondary metabolites during oxidative stress. Through PCR amplification, we analyzed the GSTM1 gene in DNA samples from 25 patients with POAG and 25 controls; 14 of the patients presented the GSTM1 gene null polymorphism while only eight of the control group had this gene.Although the POAG patients had a higher frequency of GSTM1, the difference was not significant (P = 0.0874); this lack of significance could be due to the small sample size.

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

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.

Evaluation of functional genetic variants for breast cancer risk: results from the Shanghai breast cancer study

In previous studies among 1,144 cases and 1,256 controls recruited in stage 1 of the Shanghai Breast Cancer Study (SBCS I; 1996-1998), 18 known or potentially functional single nucleotide polymorphisms (SNPs) in 16 genes were found to be associated with breast cancer risk. The authors evaluated these associations among 1,918 cases and 1,819 controls recruited in stage 2 of the SBCS (SBCS II; 2002-2005) using genetic effect models and subgroup analyses predetermined from SBCS I results. Five SNPs (AHR rs2066853, ATM rs1003623, ESR1 rs2234693, GSTP1 rs1695, and SHBG rs6259) showed generally consistent results in SBCS I and SBCS II and statistically significant associations with breast cancer risk in combined analyses, mostly in subgroups defined by age or menopausal status. Further, the relation between breast cancer risk and SHBG rs6259 was found to vary by body mass index (weight (kg)/height (m)(2)) (P for interaction = 0.003). The strongest reduction in risk associated with SHBG rs6259 was found for lean (body mass index <23) postmenopausal minor allele carriers (odds ratio = 0.6, 95% confidence interval: 0.5, 0.8; P = 4.6 × 10(-4)). This biologically plausible and highly significant finding provides strong evidence for a true association among Asian women. This study also highlights the value of gene-environment interaction analyses in evaluating genetic factors for complex diseases.

Are GSTM1, GSTT1 and CAG repeat length of androgen receptor gene polymorphisms associated with risk of prostate cancer in Iranian patients?

We conducted this study to investigate whether CAG repeat length in androgen receptor gene and GSTM1 and GSTT1 polymorphisms influence prostate cancer risk in Iranian newly diagnosed cancer patients compared to age-matched BPH group and healthy individuals. DNA from 110 pathologically-confirmed prostate cancer patients, 99 age-matched men with Benign Prostatic Hyperplasia (BPH) and 100 healthy individuals were extracted and amplified by polymerase chain reaction (PCR). PCR products were examined by electrophoresis and sequencing. The mean number of CAG repeat in prostate cancer patients was significantly smaller than normal (19.9 vs 22.8; p < 0.0001) and BPH groups (19.9 vs 21.9; P < 0.0001) The mean difference between normal individuals and BPH group was also significant (21.9 vs. 22.8; P = 0.003). Presence of GSTM1 null genotype were significantly higher in cancer and BPH group vs. normal individuals (both P values < 0.0001). there was not seen association between GSTT1 null or positive genotype with cancer risk, but analysis of GSTM1 null and GSTT1 positive in combination was statistically associated with Prostate cancer risk (OR = 8.4, 95% CI 1.53-46.73). Our results showed that CAG repeat polymorphism in AR gene may act as a risk modifier and GSTM1 null genotypes also may be contributed to prostate cancer susceptibility in Iranian patients.

Association of GSTM1T1 genes with COPD and prostate cancer in north Indian population

The glutathione S-transferase (GST) family of enzymes is known to play a pivotal role in phase II of biotransformation of xenobiotics, environmental carcinogens and pharmacological drugs. The objective of the present study was to investigate the role of GSTM1 and GSTT1 null genotypes as risk factors for chronic obstructive pulmonary disease (COPD) and prostate cancer. The subjects appraised were 200 COPD cases, 150 prostate cancer cases, 150 benign prostatic hyperplasia (BPH) cases, 200 age matched controls for COPD and 172 age matched controls for prostate cancer. GSTM1 and GSTT1 null genotype was found to confer 2.5 (OR 2.45; 95% CI 1.56-3.82; P value = 0.00008) and 2.4-fold (OR 2.39; 95% CI 1.36-4.20; P value = 0.002) significant higher risk for prostate cancer. Smoking imparted a 2.2-fold significant risk of prostate cancer cases (OR 2.23; 95% CI 1.36-3.65 P value = 0.001) and twofold risk in BPH (OR 2.09; 95% CI 1.26-3.46; P value = 0.005). In case of COPD only null genotype of GSTT1 has shown 2.1-fold (OR 2.11; 95% CI 1.22-3.62; P value = 0.007) significant increased risk.

Distribution of glutathione S-transferase T1 and M1 genes polymorphisms in North East Indians: a potential report

BACKGROUND

Detoxifying glutathione S-transferase (GST) gene polymorphisms show variation in different ethnic populations. GST detoxifies and metabolizes carcinogens, including oxygen free radicals. GST polymorphisms have been associated with susceptibility to different diseases. In the current study, allelic polymorphisms of GSTM1 and GSTT1 were analyzed in three ethnic groups of North East (NE) India where a high prevalence of various cancers and other diseases such as hypertension, tuberculosis, and asthma have been reported.

METHODS

We compared the prevalence of GSTT1 and GSTM1 deletion genotypes, which were determined by multiplex polymerase chain reaction, in 422 voluntary, healthy NE Indians with those of other populations. The data was statistically analyzed.

RESULTS

The GSTT1-null genotype was found in 51%, 34.3%, and 15.7% of individuals (from Mizoram, Sikkim, and Assam regions of NE India, respectively), whereas the GSTM1-null genotype was found in 46.9%, 46%, and 35% of individuals from the same areas.

CONCLUSIONS

The NE Indians differ from the rest of the Indian population with reference to genotypic distribution of GST polymorphisms but the frequency was found to be similar to that which has been reported from China. This may explain the hypothesis of the common ancestral origin of both the NE Indians and the Chinese and a higher frequency of cancers such as gastric, esophageal, and oral cancers, which has been reported from these regions. This study establishes baseline frequency data for GST polymorphisms for future case control studies on the role these polymorphisms play with regard to diseases. The results presented here provide the first report on GST polymorphisms in the NE Indian population.

UGT2B17 and SULT1A1 gene copy number variation (CNV) detection by LabChip microfluidic technology

BACKGROUND

Gene copy number variations (CNVs) are increasingly recognized to play important roles in the expression of genes and hence on their respective enzymatic activities. This has been demonstrated for a number of drug metabolizing genes, such as UDP-glucuronosyltransferases 2B17 (UGT2B17) and sulfotransferase 1A1 (SULT1A1), which are subject to genetic heterogeneity, including CNV. Quantitative assays to assess gene copy number are therefore becoming an integral part of accurate genotype assessment and phenotype prediction.

METHODS

In this study, we evaluated a microfluidics-based system, the Bio-Rad Experion system, to determine the power and utility of this platform to detect UGT2B17 and SULT1A1 CNV in DNA samples derived from blood and tissue. UGT2B17 is known to present with 0, 1 or 2 and SULT1A1 with up to 5 gene copies.

RESULTS

Distinct clustering (p<0.001) into copy number groups was achieved for both genes. DNA samples derived from blood exhibited less inter-run variability compared to DNA samples obtained from liver tissue. This variability may be caused by tissue-specific PCR inhibitors as it could be overcome by using DNA from another tissue, or after the DNA had undergone whole genome amplification.

CONCLUSIONS

This method produced results comparable to those reported for other quantitative test platforms.

Copy number variation in glutathione-S-transferase T1 and M1 predicts incidence and 5-year survival from prostate and bladder cancer, and incidence of corpus uteri cancer in the general population

Glutathione-S-transferase T1 (GSTT1) and GSTM1 detoxify carcinogens and thus potentially contribute to inter-individual susceptibility to cancer. We determined the ability of GST copy number variation (CNV) to predict the risk of cancer in the general population. Exact copy numbers of GSTT1 and GSTM1 were measured by real-time PCR in 10 247 individuals, of whom 2090 had cancer. In men, the cumulative incidence of prostate cancer increased and the cumulative 5-year survival decreased with decreasing GSTT1 copy numbers (trends=0.02). The hazard ratios (HRs) (95% CIs) for prostate cancer and for death after prostate cancer diagnosis were, respectively, 1.2 (0.8-1.8) and 1.2 (0.6-2.1) for GSTT1*1/0, and 1.8 (1.1-3.0) and 2.2 (1.1-4.4) for GSTT1*0/0 versus GSTT1*1/1. In women, the cumulative incidence of corpus uteri cancer increased with decreasing GSTT1 copy numbers (trend=0.04). The HRs for corpus uteri cancer were, respectively, 1.8 (1.0-3.2) and 2.2 (1.0-4.6) for GSTT1*1/0 and GSTT1*0/0 versus GSTT1*1/1. Finally, the cumulative incidence of bladder cancer increased, and the cumulative 5-year survival decreased, with decreasing GSTM1 copy numbers (P=0.03-0.05). The HRs for bladder cancer were, respectively, 1.5 (0.7-3.2) and 2.0 (0.9-4.3) for GSTM1*1/0 and GSTM1*0/0 versus GSTM1*1/1. The HR for death after bladder cancer diagnosis was 1.9 (1.0-3.7) for GSTM1*0/0 versus GSTM1*1/0. In conclusion, exact CNV in GSTT1 and GSTM1 predict incidence and 5-year survival from prostate and bladder cancer, and incidence of corpus uteri cancer.

An updating meta-analysis of the GSTM1, GSTT1, and GSTP1 polymorphisms and prostate cancer: a HuGE review

It has been postulated that individuals with GSTM1, GSTT1 deficiency and, GSTP1 (105Ile/Val transition) have increased susceptibility to carcinogens and are more likely to develop prostate cancer. In recent years, GST status has been extensively studied as a prostate cancer risk factor; however, the results are inconsistent. To re-examine this controversy, we have undertaken an updating meta-analysis of 29 studies with GSTM1 genotyping (4,564 prostate cancer cases and 5,464 controls), 22 studies with GSTT1 genotyping (3,837 cases and 4,552 controls), and 24 studies with GSTP1 genotyping (5,301 cases and 5,621 controls). The random effects odds ratio was 1.33 [95% confidence interval (95% CI): 1.15, 1.55; I(2) = 68.9%, P for heterogeneity = 0.00] for the GSTM1 null versus present genotype and 1.05 (95% CI: 0.86, 1.27; I(2) = 68.2%, P for heterogeneity = 0.00) for the GSTT1 null versus present genotype, and 1.06 (95% CI: 0.91, 1.24; I(2) = 71.5%, P for heterogeneity = 0.00) for the GSTP1-Val versus GSTP1-Ile allele. For GSTM1 polymorphism, similar results reached in Caucasians and Asians, with exception for Africans. No association between GSTT1 or GSTP1 polymorphisms and prostate cancer risk was detected in different racial. In conclusion, the major finding of our study suggested that GSTM1 polymorphism conferred an increasing risk of prostate cancer on a wide population basis, however, no relationship was found between GSTT1 and GSTP1 status and the risk of prostate cancer.

Acquisition of inverted GSTM exons by an intron of primate GSTM5 gene

The human GSTM gene family is composed of five gene members, GSTM1-5, and plays an important role in detoxification. In this study, the human GSTM5 gene was found to have a long inverted repeat (LIR) in intron 5. The LIR is able to form a stem-loop structure with a 31-bp stem and a 9-nt loop. The intronic LIR was also identified in other primates but not in non-primates. The human and chimpanzee LIRs had undergone compensating mutations that make the stem loop more stable, suggesting a functional role for the LIR. Sequence homology showed that the LIR was actually a part of inverted exons acquired by the intron. Results of phylogenetic analysis indicate that the inverted exons were derived from exon 5 of GSTM4 and exon 5 of GSTM1. The intronic LIR and inverted GSTM exons can probably introduce complexity in the expression of GSTM gene family.

Polymorphisms of glutathione-S-transferase M1, T1, P1 and the risk of prostate cancer: a case-control study

Background

It has been suggested that polymorphisms in glutathione-S-transferases (GST) could predispose to prostate cancer through a heritable deficiency in detoxification pathways for environmental carcinogens. Yet, studies linking GST polymorphism and prostate cancer have so far failed to unambiguously establish this relation in patients. A retrospective study on healthy, unrelated subjects was conducted in order to estimate the population GST genotype frequencies in the Slovak population of men and compare our results with already published data (GSEC project-Genetic Susceptibility to Environmental Carcinogens). A further aim of the study was to evaluate polymorphisms in GST also in patients with prostate cancer in order to compare the evaluated proportions with those found in the control subjects.

Methods

We determined the GST genotypes in 228 healthy, unrelated subjects who attended regular prostate cancer screening between May 2005 and June 2007 and in 129 histologically verified prostate cancer patients. Analysis for the GST gene polymorphisms was performed by PCR and PCR-RFLP.

Results

We found that the GST frequencies are not significantly different from those estimated in a European multicentre study or from the results published by another group in Slovakia. Our results suggest that Val/Val genotype of GSTP1 gene could modulate the risk of prostate cancer, even if this association did not reach statistical significance. We did not observe significantly different crude rates of the GSTM1 and GSTT1 null genotypes in the men diagnosed with prostate cancer and those in the control group.

Conclusion

Understanding the contribution of GST gene polymorphisms and their interactions with other relevant factors may improve screening diagnostic assays for prostate cancer. We therefore discuss issues of study feasibility, study design, and statistical power, which should be taken into account in planning further trials.

Population-specific GSTM1 copy number variation

As one of the major glutathione conjugation enzymes, GSTM1 detoxifies a number of drugs and xenobiotics. Its expression and activity have been shown to correlate both with cancer risks and drug resistance. Through a genome-wide association study, we identified a significant association between HapMap SNP rs366631 and GSTM1 expression. In this study, utilizing lymphoblastoid cell lines derived from International HapMap Consortium CEU and YRI populations, we designed and performed site-specific genotyping assays for both rs366631 and a highly homologous GSTM1 upstream site. Copy number variation (CNV) assays were performed for three different regions of the GSTM1 gene. We demonstrated that HapMap SNP rs366631 is a non-polymorphic site. The false genotyping call arises from sequence homology, a common GSTM1 region deletion and a non-specific genotyping platform used to identify the SNP. However, the HapMap call for rs366631 genotype is an indicator of GSTM1 upstream region deletion. Furthermore, this upstream deletion can be used as a marker of GSTM1 gene deletion. Using a novel GSTM1 CNV assay, we showed a population-specific CNV in this region upstream of the gene. More than 75% of the Caucasian (CEU) samples exhibit GSTM1 deletion and none contain two copies of GSTM1. In contrast, up to 25% of African (YRI) samples were found to have two copies of GSTM1. In conclusion, HapMap rs366631 is a pseudo-SNP that can be used as a GSTM1 deletion marker. Both the pseudo-SNP allele frequency and GSTM1 upstream region CNV show population-specific patterns between CEU and YRI samples.