GSTT1 Gene Deletion Research Articles

Associations of GST Gene Polymorphisms and GST Enzyme Activity with the Development of Noise-Induced Hearing Loss in Chinese Han Males

Introduction: In noise-induced hearing loss (NIHL), glutathione S-transferases (GSTs) play a pivotal role as antioxidants in cochlear protection. Nevertheless, the variability in population and environmental factors complicates the interpretation of research findings on the association among GST gene polymorphism, GST enzyme activity, and NIHL, leading to inconsistent results. To explore the potential correlation between them, we took a cross-sectional survey. Methods: For workers with NIHL, standard 1:1 propensity score matching was applied to create a highly comparable control group. Multiplex PCR was used to detect GSTT1 and GSTM1 gene deletions, PCR-restriction fragment length polymorphism was used to detect the GSTP1 rs1695 gene polymorphism, and a GST assay kit was used to measure total plasma GST activity. Furthermore, we analyzed the relationship among GST gene polymorphism, GST enzyme activity, and NIHL. Results: This study included 144 workers with NIHL and 144 workers with normal hearing. The GSTM1 null genotype was significantly higher among workers with NIHL than controls (64.6% vs. 49.3%), regression analysis revealed a significant correlation between GSTM1 null genotype and elevated susceptibility to NIHL (p = 0.013). Workers with NIHL had significantly lower GST activity than healthy controls (p < 0.05). GST enzymes were not affected by GSTT1, GSTM1, or GSTP1 polymorphisms. Conclusion: GSTM1 null genotype but not GSTM1 alone may confer susceptibility to NIHL, and serum GST enzyme activity is linked to NIHL.

Can pharmacogenetics impact the therapeutic effect of cytarabine and anthracyclines in adult acute myeloid leukaemia patients?: A Serbian experience.

Cytarabine-anthracycline-based induction chemotherapy remains the standard of care for remission induction among patients with newly diagnosed acute myeloid leukaemia (AML). There are remarkable differences in therapy response among AML patients. This fact could be partly explained by the patients' genetic variability related to the metabolic paths of cytarabine and anthracyclines. This study aims to evaluate the effect of variants in pharmacogenes SLC29A1, DCK, ABCB1, GSTM1, and GSTT1, as well as laboratory and AML-related parameters on clinical outcomes in adult AML patients. A total of 100 AML patients were included in the study. Pharmacogenetic variants SLC29A1 rs9394992, DCK rs12648166, ABCB1 rs2032582, and GSTM1 and GSTT1 gene deletions were detected by methodology based on PCR, fragment analysis and direct sequencing. The methods of descriptive and analytic statistics were used. Survival analysis was done using the Kaplan-Meier method using the Log-Rank test. This is the first study of adult AML pharmacogenetics in the Serbian population. Clinical outcomes in our cohort of AML patients were not impacted by analysed variants in SLC29A1, DCK, ABCB1 and GSTT1, and GSTM1 genes, independently or in combinations. Achievement of complete remission was identified as an independent prognostic indicator of clinical outcome. The population-specific genomic profile has to be considered in pharmacogenetics. Since the data on AML pharmacogenetics in European populations is limited, our results contribute to knowledge in this field and strongly indicate that a high-throughput approach must be applied to find particular pharmacogenetic markers of AML in the European population.

P443: IMPACT OF PHARMACOGENETIC VARIANTS ON CYTARABINE AND ANTHRACYCLINE EFFECT ON OUTCOMES IN ADULT AML PATIENTS

Background: Acute myeloid leukaemia (AML) is primarily treated with combination of cytarabine and anthracyclines. Despite high remission rates, the 5-year overall survival (OS) is <50% and <20% for<60-year-old a ≥60-year-old patients, respectively. This grim clinical outcome could be partly explained by the patients’ genetic variability of proteins involved in metabolic paths of cytarabine and anthracyclines. Pharmacogenetic variants of the main cytarabine membrane transporter SLC29A1 (solute carrier family 29 member 1), DCK (Deoxycytidine kinase) the first enzyme in cytarabine stepwise activation process, genes coding main anthracycline efflux pump ABCB1 (ATP binding cassette) and genes coding glutathione S-transferases GSTM1 and GSTT1, main cytosolic detoxifiers od anthracycline-induced oxidative stress, are shown to influence clinical outcome in AML patients. Aims: to evaluate: 1) the effects of variants in pharmacogenes SLC29A1, DCK, ABCB1, GSTM1 and GSTT1, on complete remission (CR) and relapse rate (RR), disease free survival (DFS) and overall survival (OS), 2) the influence of demographic, laboratory and AML-related parameters on CR, RR, DFS and OS. Methods: 100 newly-diagnosed consenting adults (18-62 years old) diagnosed with AML, except acute promyelocytic leukaemia in Clinic of Haematology UCCS from January 2015 to January 2018, were included in retrospective cohort. Patients received one or two inductions ‘’3 + 7’’ cycles. In patients achieving CR either three consolidation cycles with high/intermediate doses of cytarabine or allogenic SCT in selected patients were performed. Demographic, standard laboratory and AML-related parameters (blood/bone marrow blast percentage, cytologic, flow cytometry and genetic markers enabling ELN risk stratification were collected from patients’ health records. Variants SLC29A1 rs9394992, DCK rs12648166, ABCB1 rs2032582 and GSTM1 and GSTT1 gene deletions were detected by methodology based on PCR, fragment analysis and direct sequencing. The study was approved by the Ethics Committee of the UCCS. The methods of descriptive and analytic statistics were used, while survival analysis was done by the Kaplan-Meier method using the Log-Rank test. Results: 100 patients (53 males) were included in the study, with the median age of 51 (range 18-62). Median laboratory parameters were: WBC 15.5x109/L (range 1-348.8), Hgb 97g/L (range 20-166), Plt 53.5 (range 1-422), LDH 249U/L (1-4169). CD34 was positive in 56% patients. According to ELN 15, 55 and 30 patients were classified in favorable, intermediate and adverse risk group, respectively. CR was achieved in 57 patients (41 after the first and 16 after the second induction cycle). A total of 34% of patients relapsed. Median DFS was 5.3 months (range 0.25-61.5), while median OS was 6 months (range 0.3-75). There was a significant difference in median DFS between CC, CT and TT genotype of SLC29A1: 13, 8 and 1.75 months, respectively (p=0.00037). Median DFS was significantly decreased in null genotype of GSTM1 (9.5 (null) vs 18 months (non-null); p=0.028). Significant difference in OS within ABCB1 genotypes TT, GG, GT and AG+AT was registered: 13, 7, 6.5 and 3 months, respectively (p=0.0036). Other parameters did not differ significantly. Summary/Conclusion: Our results, regarding impact of variants of SLC29A1, GSTM1 on DFS and impact of variant ABCB1 on OS in AML patients, are in line with previous studies. Although further studies, with larger cohorts, are needed, these pharmacogenetic variants show a potential to become prognostic markers in AML.

Association of Genetic Polymorphisms in Oxidative Stress and Inflammation Pathways with Glaucoma Risk and Phenotype.

Oxidative stress and neuroinflammation are involved in the pathogenesis and progression of glaucoma. Our aim was to evaluate the impact of selected single-nucleotide polymorphisms in inflammation and oxidative stress genes on the risk of glaucoma, the patients’ clinical characteristics and the glaucoma phenotype. In total, 307 patients with primary open-angle glaucoma or ocular hypertension were enrolled. The control group included 339 healthy Slovenian blood donors. DNA was isolated from peripheral blood. Genotyping was performed for SOD2 rs4880, CAT rs1001179, GPX1 rs1050450, GSTP1 rs1695, GSTM1 gene deletion, GSTT1 gene deletion, IL1B rs1143623, IL1B rs16944, IL6 rs1800795 and TNF rs1800629. We found a nominally significant association of GSTM1 gene deletion with decreased risk of ocular hypertension and a protective role of IL1B rs16944 and IL6 rs1800629 in the risk of glaucoma. The CT and TT genotypes of GPX1 rs1050450 were significantly associated with advanced disease, lower intraocular pressure and a larger vertical cup–disc ratio. In conclusion, genetic variability in IL1B and IL6 may be associated with glaucoma risk, while GPX and TNF may be associated with the glaucoma phenotype. In the future, improved knowledge of these pathways has the potential for new strategies and personalised treatment of glaucoma.

Ethnic differences in excretion of butadiene-DNA adducts by current smokers.

1,3-Butadiene (BD) is a known human carcinogen used in the synthetic polymer industry and also found in cigarette smoke, automobile exhaust and wood burning smoke. BD is metabolically activated by cytochrome P450 monooxygenases (CYP) 2E1 and 2A6 to 3,4-epoxy-1-butene (EB), which can be detoxified by GST-catalyzed glutathione conjugation or hydrolysis. We have previously observed ethnic differences in urinary levels of EB-mercapturic acids in white, Japanese American and Native Hawaiian smokers. In the present study, similar analyses were extended to urinary BD-DNA adducts. BD-induced N7-(1-hydroxy-3-buten-2-yl) guanine (EB-GII) adducts were quantified in urine samples obtained from smokers and non-smokers belonging to three racial/ethnic groups: white, Japanese American and Native Hawaiian. After adjusting for sex, age, nicotine equivalents, body mass index and batch, we found that Japanese American smokers excreted significantly higher amounts of urinary EB-GII than whites [1.45 (95% confidence interval: 1.12-1.87) versus 0.68 (95% confidence interval: 0.52-0.85) fmol/ml urine, P = 4 × 10-5]. Levels of urinary EB-GII in Native Hawaiian smokers were not different from those in whites [0.67 (95% confidence interval: 0.51-0.84) fmol/ml urine, P = 0.938]. There were no racial/ethnic differences in urinary EB-GII adduct levels in non-smokers. Racial/ethnic differences in urinary EB-GII adduct levels in smokers could not be explained by GSTT1 gene deletion or CYP2A6 enzymatic activity. Urinary EB-GII adduct levels in smokers were significantly associated with concentrations of BD metabolite dihyroxybutyl mercapturic acid. Overall, our results reveal that urinary EB-GII adducts in smokers differ across racial/ethnic groups. Future studies are required to understand genetic and epigenetic factors that may be responsible for these differences.

ROLE OF GENETIC PREDISPOSITION, GENE POLYMORPHISM OF GLUTATHIONE-S-TRANSFERASE (GSTT1, GSTM1, GSTP1) AND SOME ADVERSE FACTORS IN DEVELOPMENT OF BRONCHIAL ASTHMA IN CHILDREN - RESIDENTS OF RADIOACTIVELY CONTAMINATED AREAS.

to determine the influence of hereditary predisposition, polymorphism of GSTT1, GSTM1, GSTP1 genes andenvironmental factors on the development of bronchial asthma in children - residents of radioactively contaminat-ed areas. School-age children-residents of radioactively contaminated areas with bronchial asthma,and those without clinical signs of respiratory pathology were examined. Genetic, medical, biological and social riskfactors were determined based on the study of anamnestic data and medical records. Ventilation lung capacity wasassessed by the method of computer spirometry. Molecular genetic studies were carried out using polymerase chainreaction (PCR) and restriction fragment length polymorphism (RFLP) for further analysis. Molecular genetic studies of the distribution of genotypes and frequencies of polymorphic variants of thegenes GSTT1, GSTM1, GSTP1 were performed in children living under long-term intake of 137Cs by food chains. It wasfound that in children with BA the tendency to frequency of the deletion variant of the GSTT1 and GSTM1 genes incomparison with children without bronchial and pulmonary pathology was increased. The study of distributing theGSTP1 A313G gene polymorphic variants revealed in children with BA a significant increase in the frequency of AG-genotype, compared with the data of reference group. Adverse factors that increase the risk of developing bron-choobstructive disorders and the probability of their implementation in the form of bronchial asthma in children -residents of RCA have been identified. It is established that among them the leading role is played by hereditarypredisposition to this disease. On the part of the child, such negative factors were unfavorable conditions of fetaldevelopment, the presence of signs of exudative-catarrhal diathesis, manifestations of allergies and frequent respi-ratory diseases from the first months of life. It was found that the risk of developing BA was significantly increasedin children with the GSTT1 and GSTM1 gene deletion genotypes; an increased risk of developing BA in children witha combination of the GSTP1 A313G gene polymorphism with deletion polymorphism of the GSTT1 or GSTM1 gene wasdetermined. Сonclusion. Оne of the leading mechanisms, due to which there is a realization of hereditary predisposition tobronchial asthma in children living under constant intake of radionuclides with a long half-life, is the polymorphismof certain glutathione-S-transferase genes, namely, GSTT1, GSTM1 and A313G gene deletion polymorphism and GSTP1gene polymorphism.

Detection of glutathione S-transferases M1, T1 gene deletions among cancer patients in Mongolia

Various types of toxic xenobiotic and electrophilic compounds, which were formed from the glutathione S-transferases cell metabolism and the oxidation stress, are the group enzymes with detoxification roles that are involved in the metabolism phase II. During the GSTM1 and GSTT1 gene homozygous deletion, the above enzymes completely lose their activity and consequently somatic mutation is formed. Furthermore, it is considered that it might have increased the risk of cancer. Therefore, the research works which connected the GSTMI and GSTTI gene deletion with the cancer of kidney, lung, prostate, breast, stomach, esophagus, large and narrow intestines. In this study, two gene deletion distribution is detected for cancer patients. We collected the blood samples of 60 patients who have been diagnosed with cancer. The DNA was extracted and the GSTM1 and GSTT1 genes were amplified using multiplex PCR. According to our research, the above two gene deletion is predominant among patients who have cancer. The results showed that from the total 60 patients GSTM1 and GSTT1 both deletions, GSTM1 gene deletion - 35%, GSTM1 gene deletion - 25%, GSTT1 gene deletion - 26.7%, GSTM1 and GSTT1 both positive -13.3 %. Therefore, we think that in order to prevent tumor and cancer, these gene mutations must be revealed and it is important to bring the risky group under medical control and assist them in order to prevent them from this disease.

Role of GSTM1 and GSTT1 genotypes in differentiated thyroid cancer and interaction with lifestyle factors: Results from case-control studies in France and New Caledonia.

BackgroundGSTM1 and GSTT1 are involved in detoxification of xenobiotics, products of oxidative stress and in steroid hormones metabolism. We investigated whether GSTM1 and GSTT1 gene deletion was associated with DTC risk and explored interaction with non-genetic risk factors of DTC.MethodsThe study included 661 DTC cases and 736 controls from two case-control studies conducted in France and New Caledonia. Odds ratios (OR) and their confidence interval (CI) for DTC associated with GST genotypes, alcohol drinking, tobacco smoking, body mass index and hormonal factors were calculated using logistic regression models.ResultsResults are presented for Europeans and Melanesians combined, as no heterogeneity between groups was detected. We found that DTC risk increased with obesity and decrease with alcohol drinking. After stratification by gene deletion status, the OR for obesity was 5.75, (95%CI 2.25–14.7) among individuals with GSTT1 and GSTM1-deleted genotype, and 1.26, (95%CI 0.89–1.77) in carriers of both genes (p-interaction = 0.02). The OR for drinking ≥1 glass/week was 0.33 (95%CI 0.15–0.74) in GSTT1-null individuals while it was 1.01 (95%CI 0.67–1.52) in non-null carriers of the gene (p-interaction = 0.01). No interaction between GST genotypes and other non-genetic risk factors was detected.ConclusionGSTM1 and GSTT1 genotypes may modulate the DTC risk associated with BMI and alcohol consumption.

Interaction between dietary acrylamide intake and genetic variants for estrogen receptor-positive breast cancer risk

PurposeThe association between dietary acrylamide intake and estrogen receptor-positive (ER+) breast cancer risk in epidemiological studies is inconsistent. By analyzing gene-acrylamide interactions for ER+ breast cancer risk, we aimed to clarify the role of acrylamide intake in ER+ breast cancer etiology.MethodsThe prospective Netherlands Cohort Study on diet and cancer includes 62,573 women, aged 55–69 years. At baseline, a random subcohort of 2589 women was sampled from the total cohort for a case–cohort analysis approach. Dietary acrylamide intake of subcohort members (n = 1449) and ER+ breast cancer cases (n = 844) was assessed with a food frequency questionnaire. We genotyped single nucleotide polymorphisms (SNPs) in genes in acrylamide metabolism, sex steroid systems, oxidative stress and DNA repair. Multiplicative interaction between acrylamide intake and SNPs was assessed with Cox proportional hazards analysis, based on 20.3 years of follow-up.ResultsUnexpectedly, there was a statistically non-significant inverse association between acrylamide and ER+ breast cancer risk among all women but with no clear dose–response relationship, and no association among never smokers. Among the results for 57 SNPs and 2 gene deletions, rs1056827 in CYP1B1, rs2959008 and rs7173655 in CYP11A1, the GSTT1 gene deletion, and rs1052133 in hOGG1 showed a statistically significant interaction with acrylamide intake for ER+ breast cancer risk.ConclusionsThis study did not provide evidence for a positive association between acrylamide intake and ER+ breast cancer risk. If anything, acrylamide was associated with a decreased ER+ breast cancer risk. The interaction with SNPs in CYP1B1 and CYP11A1 suggests that acrylamide may influence ER+ breast cancer risk through sex hormone pathways.

Lung cancer survival and deletion of GSTM1 and GSTT1 genes. A case-series from Spain.

Lung cancer has a high incidence, and only 15% of all cases are alive 5 years after the diagnosis. Identifying the role of the genes implicated in the success of chemotherapy agents is crucial to predict survival. The objective of the study was to assess the effect of GSTM1 and GSTT1 gene deletion on lung cancer survival. A consecutive sampling of lung cancer cases was performed in 1999-2000 at the University Hospital of Santiago de Compostela, Spain, and GSTM1 and GSTT1 genes were genotyped. The effect of GSTM1 and GSTT1 deletion on survival was analyzed with the logrank test and with Cox regression. A total of 132 individuals were included, and more than half of them had stage IV lung cancer at diagnosis. Survival was similar irrespective of the presence or absence of the GSTM1 gene, whereas those with deleted GSTT1 had a significantly shorter survival. In multivariate Cox regression analysis, no significant effect was observed for the deletion of any of the genes, although there was a tendency towards a worse survival for those with deletion of GSTT1. The main limitation was that stage at diagnosis could not be considered in the analysis since most of the patients were diagnosed at stage IV. GSTT1 appears to influence lung cancer survival whereas GSTM1 seems to have no effect.

Glutathione S-Transferase M1 and T1 Gene Deletions and Susceptibility to Acute Lymphoblastic Leukemia (ALL) in adults.

Objective:Biotransformation of xenobiotics are critical for their metabolism and removal from the body which is carried out by xenobiotic metabolizing enzymes. Individuals carrying variants of genes that encode these enzymes have an altered ability to metabolize xenobiotics which may lead to an increased risk of acute lymphoblastic leukemia. The current study aimed to investigate the impact of GSTM1 and GSTT1 gene deletions in causing predisposition to adult ALL.Methods:The current case-control study involved 62 adult ALL patients and 62 age and gender matched healthy controls. Whole blood samples processed with standard phenol chloroform protocol for DNA isolation were genotyped using multiplex PCR approach for simultaneous identification of GSTM1 and GSTT1 deletions. The genotype frequency obtained for patients was compared to controls using odds ratio and chi-square.Results:The null genotype frequency of GSTM1 and GSTT1 in a group of adult ALL patients from Pakistan were 47% and 11% respectively. Deletion of GSTM1 and GSTT1 did not show statistically significant association with adult ALL (p=0.86 and p=0.35 respectively). The combined GSTM1/GSTT1 deletion was observed in 2% patients and was not significantly associated with ALL in adults (p=0.85).Conclusions:The results reveal that homozygous null polymorphism of GSTM1 and GSTT1genes does not influence ALL susceptibility among adult patients. Cancer susceptibility associated with GST polymorphism varies with ethnic and geographic differences. Therefore, further investigation on different populations is needed to understand the role of these genetic variations in modifying adult ALL risk.

Polymorphisms and Protein Expressions of Glutathione S-Transferase M1 and T1 in Non-Small Cell Lung Cancer.

The deletion polymorphisms of glutathione S-transferase (GST) GSTM1 and GSTT1 genes result in the absence of the corresponding protein, which decreases the detoxification of carcinogens. Studies evaluating polymorphisms and protein expressions in the same patients are limited. Therefore, in this study, we aimed to investigate the association between polymorphisms and protein expressions of GSTM1 and GSTT1 in lung tissues of patients with non-small cell lung cancer (NSCLC). For protein expression and gene deletion studies, tumor and surrounding tumor free (normal) tissue of 33 patients with NSCLC were used. In paraffin-embedded tissues, immunohistochemistry was used to detect protein expressions, and multiplex polymerase chain reaction amplification was used to identify gene deletions. GSTM1 and GSTT1 protein expressions were not detected in patients with GSTM1 and GSTT1 gene deletions, whereas protein expressions were detected in lung tissues of all patients carrying GSTM1 and GSTT1 genes. The protein expression level of GSTT1 was 2.0-fold higher in tumors of patients lacking GSTM1 genes than those with GSTM1 genes (p=0.018). Protein expression of GSTM1 was statistically higher in tumor tissues than in normal tissues of patients with GSTM1 genes (p=0.001). These results show that a) there is an association between gene deletions and protein expressions of GSTM1 and GSTT1 in patients with NSCLC, b) in the absence of GSTM1 genes, enhancement of expression of GSTT1 in tumors is likely to show that GSTT1 increases its capacity to detoxify the toxic electrophiles in tumors, and c) GSTM1 protein expression is higher in tumors compared with normal lung tissues of patients with NSCLC.

Genetic Determinants of 1,3-Butadiene Metabolism and Detoxification in Three Populations of Smokers with Different Risks of Lung Cancer.

Background: 1,3-Butadiene (BD) is an important carcinogen in tobacco smoke that undergoes metabolic activation to DNA-reactive epoxides. These species can be detoxified via glutathione conjugation and excreted in urine as the corresponding N-acetylcysteine conjugates. We hypothesize that single nucleotide polymorphisms (SNPs) in BD-metabolizing genes may change the balance of BD bioactivation and detoxification in White, Japanese American, and African American smokers, potentially contributing to ethnic differences in lung cancer risk.Methods: We measured the levels of BD metabolites, 1- and 2-(N-acetyl-L-cysteine-S-yl)-1-hydroxybut-3-ene (MHBMA) and N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine (DHBMA), in urine samples from a total of 1,072 White, Japanese American, and African American smokers and adjusted these values for body mass index, age, batch, and total nicotine equivalents. We also conducted a genome-wide association study to identify genetic determinants of BD metabolism.Results: We found that mean urinary MHBMA concentrations differed significantly by ethnicity (P = 4.0 × 10-25). African Americans excreted the highest levels of MHBMA followed by Whites and Japanese Americans. MHBMA levels were affected by GSTT1 gene copy number (P < 0.0001); conditional on GSTT1, no other polymorphisms showed a significant association. Urinary DHBMA levels also differed between ethnic groups (P = 3.3 × 10-4), but were not affected by GSTT1 copy number (P = 0.226).Conclusions:GSTT1 gene deletion has a strong effect on urinary MHBMA levels, and therefore BD metabolism, in smokers.Impact: Our results show that the order of MHBMA levels among ethnic groups is consistent with their respective lung cancer risk and can be partially explained by GSTT1 genotype. Cancer Epidemiol Biomarkers Prev; 26(7); 1034-42. ©2017 AACR.

Effects of Glutathione S-Transferase Gene Polymorphisms and Antioxidant Capacity per Unit Albumin on the Pathogenesis of Chronic Obstructive Pulmonary Disease.

Objectives To study the effects of GSTM1, GSTT1 gene polymorphisms, and organism antioxidant capacity and related indicators such as antioxidant capacity per unit of albumin (AC/ALB) on chronic obstructive pulmonary disease (COPD). Methods Using polymerase chain reaction technology, GSTM1 and GSTT1 gene polymorphisms were detected in 33 COPD patients and 33 healthy people. The total antioxidant capacity (TAC) found in serum was determined using the I2/KI potentiometric, KMnO4 microtitration, and H2O2 potentiometric methods. The AC/ALB was defined as the TAC divided by the serum albumin concentration. Logistic regression analysis was carried out with biochemical screening indices, which was found to be closely related with the incidence of COPD. Results The GSTM1 and GSTT1 gene deletion rate in the COPD group was significantly higher than that in the control group (P < 0.05). The differences in serum TAC between the COPD and control groups, GSTM1 (+) and GSTM1 (−) groups, and GSTT1 (+) and GSTT1 (−) groups were statistically significant (P < 0.001). In addition, there was a significant difference in the AC/ALB between the COPD and control groups (P < 0.05). Logistic regression analysis showed that the incidence of COPD was closely related to the AC/ALB (P < 0.05). Conclusions GSTM1 and GSTT1 gene polymorphisms are closely correlated with the pathogenesis of COPD, while the AC/ALB plays a decisive role in the occurrence and development of COPD.

Gene polymorphism profiles of drug-metabolising enzymes GSTM1, GSTT1 and GSTP1 in an Argentinian population

Background: Glutathione S-transferases (GSTs) are drug-metabolising enzymes involved in biotransformation of carcinogens, drugs, xenobiotics and oxygen free radicals. Polymorphisms of GST genes contribute to inter-individual and population variability in the susceptibility to environmental risk factors, cancer predisposition and pharmacotherapy responses. However, data about GST variability in Argentina are lacking.Aim: The purpose was to determine the prevalence of GSTM1, GSTT1 and GSTP1 polymorphisms in the general population from a central region of Argentina and to perform inter-population comparisons.Subjects and methods: GSTM1 and GSTT1 gene deletions and GSTP1 c.313A > G were genotyped by PCR assays in 609 healthy and unrelated Argentinians.Results: The frequencies of variant genotypes in Argentinians were GSTM1-null (45%), GSTT1-null (17%) and GSTP1-GG (11%). GSTM1-present genotype was significantly associated with GSTP1-AG or GSTP1-GG variants (p = 0.037; p = 0.034, respectively). Comparison with worldwide populations demonstrated that the GST distributions in Argentina are similar to those reported for Italy and Spain, whereas significant differences were observed regarding Asian and African populations (p < 0.001).Conclusion: This study has determined, for the first time, the normative profile of three pharmacogenetically relevant polymorphisms (GSTM1, GSTT1 and GSTP1) in the largest Argentinian cohort described to date, providing the basis for further epidemiological and pharmacogenetic studies in this country.

Oxidative Stress and Genetic Variants of Xenobiotic-Metabolising Enzymes Associated with COPD Development and Severity in Serbian Adults

ABSTRACTThe genetic and non-genetic factors that contribute to the development of chronic obstructive pulmonary disease (COPD) are still poorly understood. We investigated the potential role of genetic variants of xenobiotic-metabolising enzymes (glutathione-S-transferase M1, GSTM1; glutathione-S-transferase T1, GSTT1; microsomal epoxide hydrolase, mEH), oxidative stress (assessed by urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine, 8-oxodG/creatinine), sex, ageing and smoking habits on susceptibility to development of COPD and its severity in Serbian population. The investigated population consisted of 153 healthy subjects (85 males and 68 females) and 71 patients with COPD (33 males and 38 females). Detection of GSTM1*null, GSTT1*null, mEH Tyr113His and mEH His139Arg gene variants was performed by PCR/RFLP method. Urinary 8-oxodG was determined using HPLC-MS/MS, and expressed as 8-oxodG/creatinine. We revealed that increased urinary 8-oxodG/creatinine and leucocytosis are the strongest independent predictors for COPD development. Increased level of oxidative stress increased the risk for COPD in males [odds ratio (OR), 95% confidence interval (CI): 8.42, 2.26–31.28], more than in females (OR, 95% CI: 3.60, 1.37–9.45). Additionally, independent predictors for COPD were ageing in males (OR, 95% CI: 1.29, 1.12–1.48), while in females they were at least one GSTM1 or GSTT1 gene deletion in combination (OR, 95% CI: 23.67, 2.62–213.46), and increased cumulative cigarette consumption (OR, 95% CI: 1.09, 1.01–1.16). Severity of COPD was associated with the combined effect of low mEH activity phenotype, high level of oxidative stress and heavy smoking. In conclusion, early identification of GSTM1*null or GSTT1*null genotypes in females, low mEH activity phenotype in heavy smokers and monitoring of oxidative stress level can be useful diagnostic and prognostic biomarkers.

The synergy of tobacco and alcohol and glutathione S-transferase θ 1 gene deletion and oral squamous cell carcinoma.

Background:Oral squamous cell carcinoma (OSCC) is the leading cancer among males in India. It is related to tobacco habits and alcohol consumption as well as the individual susceptibility for xenobiotic metabolizing enzyme polymorphisms. Glutathione S-transferase θ 1 (GSTT1) is a Phase II metabolic enzyme which is directly involved in catalyzing chemicals to mutagenic intermediates. This gene is characterized by genetic polymorphism resulting in complete gene deletion and subsequent absence of the enzyme, which ultimately dictates the risk of cancer development. Scraping buccal mucosa to obtain DNA from the cells is a simple, readily acceptable and rapid method to detect and assess the gene.Aim:To assess GSTT1 gene deletion in individuals giving a history of tobacco smoking and/or chewing and alcohol consumption and absence of clinically detectable lesions; and in OSCC cases to gauge if GSTT1 gene deletion confers protection to an individual and whether it can be used as a “single” marker to arrive at this conclusion. To validate the use of buccal scrape for determining the genotype of an individual by assessing the polymorphism at GSTT1 gene locus (22q11.2).Materials and Methods:Fifty-two cases were evaluated using buccal mucosal scrapes of tobacco habituates for 8 or more years, without clinically evident lesion (Group I) and from mucosa of tobacco habituates with clinically evident and histopathologically confirmed OSCC (Group II). DNA extraction and genotype at GSTT1 gene locus was determined by polymerase chain reaction assay.Statistical Analysis:The results were statistically analyzed using Chi-square test.Results:90.66% of subjects had GSTT1 null genotype in Group I subjects. In Group II, subjects with both clinically and histopathologically diagnosed oral cancer, about 76.96% had GSTT1 null genotype.Conclusion:GSTT1 null genotype confers protection to individuals with tobacco habits and alcohol consumption, predominantly to those who used chewable form of tobacco and especially among female population. However, the influence of many other environmental, genetic and epigenetic factors should be considered for the genesis/occurrence of cancer.

Exploring the Significance of TP53, ABCB1 and GST Polymorphisms on Susceptibility and Pharmacogenetics in Argentinian Patients with Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is specifically associated with the t(9;22)(q34;q11) reciprocal translocation giving rise to the Philadelphia chromosome and the subsequent formation of the BCR/ABL1 fusion gene, encoding a constitutively active tyrosine kinase. Advances in targeted therapies in chronic phase CML, notably the use of tyrosine kinase inhibitors (TKIs) such as imatinib mesylate (IM), have achieved successful treatment outcomes. However, some patients fail to achieve optimal response, and a substantial proportion of patients develop resistance to IM, which is frequently associated with mutations in the ABL kinase domain. Although BCR/ABL1 fusion oncogene is a key molecular marker involved in the pathogenesis and the clinical course of CML, molecular or cellular events that initiate leukemogenesis or drive translocation of the BCR/ABL1 genes are incompletely understood and little is known about individual susceptibility to this disease. Moreover, it is still unclear whether BCR/ABL1 oncoprotein alone is sufficient to explain the full range of clinical responses to ITKs. There is mounting evidence that genetic factors may play an important role in susceptibility to CML and variability in drug responsiveness. Polymorphic variants of several genes are linked to variations in expression, function, drug disposition and drug response and are potential factors accounting for susceptibility to complex diseases or drug resistance as they can uniquely influence the quality and quantity of gene product. Association studies have been performed to identify genetic variants associated with CML susceptibility and progression, but data are lacking for Argentina. In the present study, we determined the distribution of polymorphisms on TP53 tumor suppressor gene, drug transporter (ABCB1) and drug-metabolizing (glutathione-S-transferases, GSTs) genes to identify markers of susceptibility and pharmacogenetic response in Argentinian patients with CML.Genomic DNA samples from peripheral blood of 141 patients (69 females/72 males, median age 50.8 ± 1.3 years,) treated with IM and 141 age and sex matched healthy controls were evaluated. IM therapy failure was defined by cytogenetics and qRT-PCR in 2 consecutive studies, finding 76 cases that fail treatment. All individuals provided their informed consent according to institutional guidelines and the study was approved by the Ethics Committee of our Institution. GSTM1 and GSTT1 gene deletion polymorphisms and single nucleotide polymorphisms (SNPs) in GSTP1 (313A> G), TP53 (215C> G) and ABCB1 (3435C> T, 1236 C> T and 2677G>T/A) were determined using PCR-based methods. BCR/ABL1 transcript level was analyzed using RT-PCR and ABL1 mutations were identified by RT-PCR and sequencing. Comparison of genotypes between patients and controls as well as regarding clinical parameters was performed by logistic regression. The Kaplan-Meier curves were analyzed using the log-rank test. The level of significance was p <0.05. The case/control association analysis highlighted that carriers of TP53 CC+CG genotypes influence CML susceptibility (p=0.007; OR: 4.5; CI: 1.5-13.3), but no other markers were significantly involved. Next, the pharmacogenetic analysis was performed associating different genotypes with molecular response and treatment failure. We determined that patients carrying GSTM1 -present genotype did not reached major molecular response (p=0.038; OR: 2.9; CI: 1.16-7.4). In addition, average time to treatment change was significantly lower for carriers of the following genotypes: ABCB1 1236TT (23 months), ABCB1 3435TT (13.6 months) and GSTM1 -present (53 months), respect to patients with other variants (p=0.017; p=0.0046 and p=0.04, respectively). Finally, patients with TP53 CC+CG polymorphisms had an increased risk of progression (p=0.039) and lower overall survival (p=0.017). These results indicate that TP53 genotype may represent a genetic cofactor that influences susceptibility to CML and genotypic variations of TP53, ABCB1 and GSTM1 may modulate the response to imatinib. DisclosuresMoiraghi:Bristol Myers Squibb: Speakers Bureau; Novartis: Speakers Bureau. Bengio:Novartis: Speakers Bureau; Bristol Myers Squibb: Speakers Bureau.

Prostate cancer and glutathione S-transferase deletions.

GSTM1 and GSTT1 gene polymorphisms have been studied in many populations to evaluate their association with prostate cancer risk with contrasting results. The current study was aimed to find out the association of GSTM1 and GSTT1 gene polymorphisms with prostate cancer in Pakistani men. This case control study included pathologically confirmed prostate cancer patients and age matched male controls. Epidemiological data was collected by a standard questionnaire and presence or absence of GSTM1 and GSTT1 gene was observed by multiplex PCR using CYP1A1 as housekeeping gene. Prostate cancer was more prevalent in age of >60 years and most of the patients were at stage IV (70 %) and have undergone surgery. Family history of cancer, smoking, metastasis and surgery were found to be significant (P<0.05) risk factors in prostate cancer development. Gleason score 7 was most prevalent (40.5 %) in prostate cancer patients. Source of drinking water, residential area, occupation, eating habits and number of family members had no association (P>0.05) with prostate cancer risk. No significant association was found when comparing GSTM1 (OR=0.78) and GSTT1 (OR=0.89) gene deletions with prostate cancer risk. Smoking and TNM staging were also not associated with deletion of GSTM1 and GSTT1 genes. Comparison of dual null deletion of both genes with prostate cancer also showed non-significant associations. Deletion of GSTM1 gene at stage IV prostate cancer patients was significantly higher compared with other stages of cancer while no significance was shown by GSTT1 gene deletion. GSTM1, GSTT1 and deletion of both GSTM1 and GSTT1 genes do not contribute towards increased risk of prostate cancer in Pakistani population.

Genetic variability of DNA repair mechanisms and glutathione-S-transferase genes influences treatment outcome in osteosarcoma

BackgroundOsteosarcoma patients are commonly treated with cisplatin-based preoperative and postoperative chemotherapy. Cisplatin binds to DNA and forms both intrastrand and interstrand crosslinks, inhibiting DNA replication. Glutathione-S-transferases (GSTs) participate in cisplatin detoxification, while several independent DNA repair mechanisms repair cisplatin-induced lesions. The aim of our study was to investigate the influence of genetic variability of DNA repair mechanisms and GSTs on efficacy and toxicity of cisplatin-based chemotherapy in osteosarcoma patients. MethodsA total of 66 osteosarcoma patients were genotyped for ERCC1, ERCC2, NBN, RAD51, XRCC3, and GSTP1 polymorphisms, as well as GSTM1 and GSTT1 gene deletion. We determined the influence of polymorphisms on survival and treatment outcome using Cox regression and logistic regression. ResultsCarriers of at least one polymorphic ERCC2 rs1799793 allele had longer event-free survival (EFS) (P=0.006; hazard ratio (HR)=0.28; 95% confidence interval (CI)=0.11–0.70). Polymorphic GSTP1 rs1138272 allele was associated with both shorter EFS and OS (P=0.005; HR=3.67; 95%CI=1.47–9.16; and P=0.004; HR=3.52; 95%CI=1.51–8.22, respectively). Compared to the reference NBN CAA haplotype, NBN CGA haplotype was associated with shorter EFS (P=0.001; HR=4.12; 95%CI=1.77–9.56). ConclusionsOur results suggest that DNA repair polymorphisms and GST polymorphisms could be used as predictive factors for cisplatin-based chemotherapy in osteosarcoma patients and could contribute to treatment personalization.