Glutathione S-transferase M1 (GSTM1) polymorphisms and lung cancer: a literature-based systematic HuGE review and meta-analysis

Association of GSTM1 and GSTT1 Null Genotypes with Toluene Diisocyanate-Induced Asthma

Background. Toluene diisocyanate (TDI) causes occupational asthma by generating oxidative stress, leading to tissue injury and inflammation. Glutathione transferases (GSTs) are detoxifying enzymes that eliminate oxidative stress. We examined whether the genotypes of the GSTM1 and GSTT1 genes are associated with TDI-induced occupational asthma (TDI-OA). Methods. The study population consisted of 26 asthmatics with a positive response to the TDI challenge (TDI-PA) and 27 asthmatics with negative responses (TDI-NA). GSTM1 and GSTT1 null and wild-type genotypes were determined using multiplex PCR. The plasma GSTM1 and GSTT1 protein concentrations were determined using ELISA. Results. The GSTM1 null genotype was more frequent in the TDI-PA than in the TDI-NA (77.8 vs. 50.0%, OR = 3.5, $p=0.03$ ), while the frequency of the GSTT1 null genotype tended to be higher in the TDI-PA than in the TDI-NA (59.3 vs. 42.3%, OR = 1.98, $p=0.21$ ). When analyzed together, the GSTM1/GSTT1 null genotype was more frequent in the TDI-PA than in the TDI-NA (48.2 vs. 15.3%, OR = 6.5, $p=0.04$ ). The decline in the FEV in 1 s after TDI challenge was higher with the GSTM1/GSTT1 null than the GSTM1 wild-type/GSTT1 null genotypes (24.29% vs. 7.47%, $p=0.02$ ). The plasma GSTM1 level was lower with the GSTM1 null than with the GSTM1 wild-type genotypes both before (13.7 vs. 16.6 ng/mg, $p=0.04$ ) and after (12.9 vs. 17.1 ng/mg, $p=0.007$ ) the TDI challenge, while the GSTT1 level was not changed with either the GSTT1 null or wild-type genotype. Conclusions. The GSTM1 null genotype, but not GSTT1 alone, may confer susceptibility to TDI-OA. However, the genetic effect of the GSTM1 null genotype may be enhanced synergistically by the GSTT1 null genotype. The genetic effect of GSTM1 was validated in the plasma as the GSTM1 protein level. Therefore, the GSTM1 and GSTT1 genotypes may be useful diagnostic markers for TDI-OA.

Genetic Biomarkers of Metabolic Detoxification for Personalized Lifestyle Medicine

Metabolic detoxification (detox)—or biotransformation—is a physiological function that removes toxic substances from our body. Genetic variability and dietary factors may affect the function of detox enzymes, thus impacting the body’s sensitivity to toxic substances of endogenous and exogenous origin. From a genetic perspective, most of the current knowledge relies on observational studies in humans or experimental models in vivo and in vitro, with very limited proof of causality and clinical value. This review provides health practitioners with a list of single nucleotide polymorphisms (SNPs) located within genes involved in Phase I and Phase II detoxification reactions, for which evidence of clinical utility does exist. We have selected these SNPs based on their association with interindividual variability of detox metabolism in response to certain nutrients in the context of human clinical trials. In order to facilitate clinical interpretation and usage of these SNPs, we provide, for each of them, a strength of evidence score based on recent guidelines for genotype-based dietary advice. We also present the association of these SNPs with functional biomarkers of detox metabolism in a pragmatic clinical trial, the LIFEHOUSE study.

Polymorphisms in DNA Repair and Xenobiotic Biotransformation Enzyme Genes and Lung Cancer Risk in Coal Mine Workers

Background: Currently coal mining employs over 7 million miners globally. This occupational setting is associated with exposure to dust particles, heavy metals, polycyclic aromatic hydrocarbons and radioactive radon, significantly increasing the risk of lung cancer (LC). The susceptibility for LC is modified by genetic variations in xenobiotic detoxification and DNA repair capacity. The aim of this study was to investigate the association between GSTM1 (deletion), APEX1 (rs1130409), XPD (rs13181) and NBS1 (rs1805794) gene polymorphisms and LC risk in patients who worked in coal mines. Methods: The study included 639 residents of the coal region of Western Siberia (Kemerovo region, Russia): 395 underground miners and 244 healthy men who do not work in industrial enterprises. Genotyping was performed using real-time and allele-specific PCR. Results: The results show that polymorphisms of APEX1 (recessive model: OR_adj = 1.87; CI 95%: 1.01–3.48) and XPD (log additive model: OR_adj = 2.25; CI 95%: 1.59–3.19) genes were associated with increased LC risk. GSTM1 large deletion l was linked with decreased risk of LC formation (OR_adj = 0.59, CI 95%: 0.36–0.98). The multifactor dimensionality reduction method for 3-loci model of gene–gene interactions showed that the GSTM1 (large deletion)—APEX1 (rs1130409)—XPD (rs13181) model was related with a risk of LC development. Conclusions: The results of this study highlight an association between gene polymorphism combinations and LC risks in coal mine workers.

Associations of short-term PM2.5 exposures with nasal oxidative stress, inflammation and lung function impairment and modification by GSTT1-null genotype: A panel study of the retired adults

PM_2.5 (particulate matter ≤2.5 μm in aerodynamic diameter) is a major urban air pollutant worldwide. Its effects on the respiratory system of the susceptible population have been less characterized. This study aimed to estimate the association of short-term PM_2.5 exposure with respiratory outcomes of the retired adults, and to examine whether these associations were stronger among the subjects with GSTT-null genotype. 32 healthy subjects (55-77 years) were recruited for five follow-up examinations. Ambient concentrations of PM_2.5 were monitored consecutively for 7 days prior to physical examination. Pulmonary outcomes including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), peak expiratory flow (PEF), and fractional exhaled nitric oxide (FeNO), and nasal fluid concentrations of 8-epi-prostaglandin F2 alpha (8-epi-PGF2α), tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8) and IL-1β were measured. A linear mixed-effect model was introduced to evaluate the associations of PM_2.5 concentrations with respiratory outcomes. Additionally, GSTT1 genotype-based stratification was performed to characterize modification on PM_2.5-related respiratory outcomes. We found that a 10 μg/m³ increase in PM_2.5 was associated with decreases of 0.52 L (95% confidence interval [CI]: -1.04, -0.002), 0.64 L (95% CI: -1.13, -0.16), 0.1 (95% CI: -0.23, 0.04) and 2.87 L/s (95% CI: -5.09, -0.64) in FVC, FEV₁, FEV₁/FVC ratio and PEF at lag 2, respectively. Meanwhile, marked increases of 80.82% (95% CI: 5.13%, 156.50%) in IL-8, 77.14% (95% CI: 1.88%, 152.40%) in IL-1β and 67.87% (95% CI: 14.85%, 120.88%) in 8-epi-PGF2α were observed as PM_2.5 concentration increased by 10 μg/m³ at lag 2. Notably, PM_2.5-associated decreases in FVC and PEF and increase in FeNO were stronger among the subjects with GSTT1-null genotype. In summary, short-term exposure to PM_2.5 is associated with nasal inflammation, oxidative stress and lung function reduction in the retired subjects. Lung function reduction and inflammation are stronger among the subjects with GSTT1-null genotype.

Individual and combined effects of GSTM1, GSTT1, and GSTP1 polymorphisms on lung cancer risk: A meta-analysis and re-analysis of systematic meta-analyses

Thirty-five previous meta-analyses have been reported on the individual glutathione S-transferase M1 (GSTM1) present/null, glutathione S-transferase T1 (GSTT1) present/null, and glutathione S-transferase P1 (GSTP1) IIe105Val polymorphisms with lung cancer (LC) risk. However, they did not appraise the credibility and explore the combined effects between the 3 genes and LC risk.We performed a meta-analysis and re-analysis of systematic previous meta-analyses to solve the above problems.Meta-analyses of Observational Studies in Epidemiology guidelines were used. Moreover, we employed false-positive report probability (FPRP), Bayesian false discovery probability (BFDP), and the Venice criteria to verify the credibility of current and previous meta-analyses.Significantly increased LC risk was considered as "highly credible" or "positive" for GSTM1 null genotype in Japanese (odds ratio (OR) = 1.30, 95% confidence interval (CI) = 1.17-1.44, I2 = 0.0%, statistical power = 0.997, FPRP = 0.008, BFDP = 0.037, and Venice criteria: AAB), for GSTT1 null genotype in Asians (OR = 1.23, 95% CI = 1.12-1.36, I2 = 49.1%, statistical power = 1.000, FPRP = 0.051, BFDP = 0.771, and Venice criteria: ABB), especially Chinese populations (OR = 1.31, 95% CI = 1.16-1.49, I2 = 48.9%, Statistical power = 0.980, FPRP = 0.039, BFDP = 0.673, and Venice criteria: ABB), and for GSTP1 IIe105Val polymorphism in Asians (Val vs IIe: OR = 1.28, 95% CI = 1.17-1.42, I2 = 30.3%, statistical power = 0.999, FPRP = 0.003, BFDP = 0.183, and Venice criteria: ABB). Significantly increased lung adenocarcinoma (AC) risk was also considered as "highly credible" or "positive" in Asians for the GSTM1 (OR = 1.35, 95% CI = 1.22-1.48, I2 = 25.5%, statistical power = 0.988, FPRP < 0.001, BFDP < 0.001, and Venice criteria: ABB) and GSTT1 (OR = 1.36, 95% CI = 1.17-1.58, I2 = 30.2%, statistical power = 0.900, FPRP = 0.061, BFDP = 0.727, and Venice criteria: ABB) null genotype.This study indicates that GSTM1 null genotype is associated with increased LC risk in Japanese and lung AC risk in Asians; GSTT1 null genotype is associated with increased LC risk in Chinese, and GSTP1 IIe105Val polymorphism is associated with increased LC risk in Asians.

Acute exposure to traffic-related air pollution alters antioxidant status in healthy adults

BACKGROUND

Exposure to traffic-related air pollution is associated with an increased risk of cardiovascular and respiratory disease. Evidence suggests that inhaled pollutants precipitate these effects via multiple pathways involving oxidative stress.

OBJECTIVE

Postulating that a decrease in circulating antioxidant levels reflect an oxidative response, we investigated the effect of inhaled diesel exhaust (DE) on the ratio of reduced to oxidized glutathione (GSH/GSSG) in healthy adults, and whether pre-exposure antioxidant supplementation blunted this response. We also examined exposure-related changes in antioxidant/stress response leukocyte gene expression (GCLc, HMOX-1, IL-6, TGFβ) and plasma IL-6 levels.

METHODS

Nineteen nonsmoking adults participated in a double-blind, randomized, four-way crossover study. Each subject completed 120-min exposures to filtered air and DE (200 μg/m3), with and without antioxidant pretreatment. Antioxidant comprised 1000 mg ascorbate for 7 days and 1200 mg N-acetylcysteine 1 day prior to exposure, with 1000 mg and 600 mg, respectively, administered 2 h prior to exposure. Whole blood glutathione was measured pre- and post-exposure; plasma IL-6 and mRNA expression were quantified pre, during and post exposure.

RESULTS

Diesel exhaust exposure was associated with significantly decreased GSH/GSSG (p = 0.001) and a 4-fold increase in IL-6 mRNA (p = 0.01) post exposure. Antioxidant pretreatment did not significantly mediate the effect of DE exposure on GSH/GSSG, though appeared to decrease the effect of exposure on IL-6 mRNA expression.

CONCLUSIONS

Acute DE inhalation induced detectable oxidative effects in healthy adults, which were not significantly attenuated by the selected antioxidant pre-treatment. This finding supports the premise that oxidative stress is one mechanism underlying the adverse effects of traffic-related air pollution.

Genetic Polymorphisms of Xenobiotic Metabolizing Genes (GSTM1, GSTT1, GSTP1), Gene-Gene Interaction with Association to Lung Cancer Risk in North India; A Case Control Study

Aim: In this case control study involving, 220 human subjects; polymorphisms in xenobiotic metabolizing genes (GST-M1, -T1 and -P1) and their association to lung cancer risk is being analysed among smokers and nonsmokers. GSTM1 or GSTT1 gene polymorphism and amino acid changes in GSTP1 have been correlated and may be associated to lung cancer risk. Other factor includes exposure to environmental pollutants and life style choices. We have explored gene-gene and gene-environment interaction in the aetiology of lung cancer risk among north Indian population. Patients and Methods: For the study we have collected 120 lung cancer patient blood samples from Kamala Nehru Memorial Cancer Hospital, Allahabad, Uttar Pradesh and 100 matched controls. DNA was isolated and GST-M1 and - T1 genotyping were assessed by multiplex PCR whereas the GSTP1 polymorphism was analysed using restriction fragment length polymorphism. The risk of lung carcinogenesis was assessed using logistic regression analysis calculating the odd ratio (OR) with 95% confidence interval (CI). Results: The risk of lung carcinogenesis was three fold higher for null GSTT1 (OR=3.045, 95%CI=1.750-5.301, p-value <0.001) genotype; whereas other two types; GSTM1 (OR= 1.342, 95% CI=0.788-2.284, p-value=0.270) and GSTP1 (OR=0.806, 95% CI=0.526-1.236, p-value=0.323) showed no association to lung cancer susceptibility respectively. Smokers diagnosed with lung cancer had more null genotypes for GSTT1 (OR=4.773, 95%CI=1.939-11.751, p<0.001). The ‘at risk’ genotype combination GSTM1 (null) /GSTT1 (null) (OR=1.76, 95%CI; 0.920-3.370, p-value=0.03) showed increased susceptibility to lung cancer risk. The genotype combination of GSTT1 (null)/GSTP1 (Ile/Ile) (p=0.009) was associated with increased lung cancer risk. Conclusion: The results of this study suggest that; GSTT1 null genotype were more susceptible for lung cancer risk and smoking increases the susceptibility for lung cancer several folds among the North Indian population. Gene-gene interaction for null genotypes of GSTM1 and GSTT1 were correlated with higher risk of having lung cancer.

Variability in ambient ozone and fine particle concentrations and population susceptibility among Canadian health regions

Objectives

To estimate the proportion of the Canadian population that is more susceptible to adverse effects of ozone (O₃) and fine particle (PM_2.5) air pollution exposure and how this varies by health region alongside ambient concentrations of O₃ and PM_2.5.

Methods

Using data from the census, the Canadian Community Health Survey, vital statistics and published literature, we generated cross-sectional estimates for 2014 of the proportions of the Canadian population considered more susceptible due to age, chronic disease, pregnancy, outdoor work, socio-economic status, and diet. We also estimated 2010–2012 average concentrations of O₃ and PM_2.5. Analyses were conducted nationally and for 110 health regions.

Results

Restrictive criteria (age < 10 or ≥ 75; asthma, chronic obstructive pulmonary disease, heart disease, or diabetes; pregnancy) suggested that approximately one third of the Canadian population is more susceptible, while inclusive criteria (restrictive plus age 10–19 and 65–74, outdoor work, less than high school education, low vitamin C intake) increased this proportion to approximately two thirds. Across health regions, estimates ranged from 24.4% to 41.2% (restrictive) and 61.2% to 87.0% (inclusive). Ten health regions were in the highest quartile of both population susceptibility and O₃ or PM_2.5 concentrations, all of which were outside major urban centres.

Conclusions

A substantial proportion of the Canadian population exhibits at least one risk factor that increases their susceptibility to adverse effects of O₃ and PM_2.5 exposure. Both risk communication and management interventions need to be increasingly targeted to regions outside large urban centres in the highest quartiles of both susceptibility and exposure.

Electronic supplementary material

The online version of this article (10.17269/s41997-018-0169-8) contains supplementary material, which is available to authorized users.

Tobacco smoking, alcohol drinking, betel quid chewing, and the risk of head and neck cancer in an East Asian population

BACKGROUND

The smoking prevalence among men in China is high, but the head and neck cancer incidence rates are low. This study's purpose was to investigate the impact of tobacco, betel quid, and alcohol on head and neck cancer risk in East Asia.

METHODS

A multicenter case-control study (921 patients with head and neck cancer and 806 controls) in East Asia was conducted. The odds ratio (OR) and 95% confidence interval (CI) were estimated using logistic regression.

RESULTS

Head and neck cancer risks were elevated for tobacco (OR = 1.58), betel quid (OR = 8.23), and alcohol (OR = 2.29). The total attributable risk of tobacco and/or alcohol was 47.2%. Tobacco/alcohol appeared to account for a small proportion of head and neck cancer among women (attributable risk of 2.2%). Betel quid chewing alone accounted for 28.7% of head and neck cancer.

CONCLUSIONS

Betel quid chewing is the strongest risk factor for oral cavity cancer in this Chinese population. Alcohol may play a larger role for head and neck cancer in this population than in European or U.S.

POPULATIONS

Glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) Polymorphisms and Lung Cancer Risk among a Select Group of Iranian People

Objective(s): Lung cancer, caused primarily by smoking, is one of the leading determinants of mortality throughout the world. Here we investigated the effects of polymorphisms in two enzymes, i.e., GSTT1 and GSTM1, related to the antioxidant defense line against carcinogens associated with lung cancer among a select group of Iranian people. Materials and Methods: One hundred and twenty lung cancer patients from two referral centers in Tehran, Iran, were recruited for comparison with 120 healthy controls. Genomic DNA was extracted from the FFPE tumor tissues of the select cases and peripheral blood buffy coats of healthy controls. The polymorphisms of GSTT1 and GSTM1 were investigated by multiplex polymerase chain reaction. Results: With the 240 samples studied, no specific relationship with lung cancer was discerned for the GSTM1 (P=0.35; OR=1/33; 95% CI=0.79-2.25) polymorphism, but the GSTT1 (P=0.005; OR=2.4; CI=1.32-4.35) gene polymorphism revealed a notable association on logistic regression, taking into account age and sex factors. Furthermore, the GSTT1 genotype distribution in patients with LSCC was different from that of healthy cases (P=0.006; OR=3.11; CI=1.38-7.04). The risk of developing lung cancer with the T0M1 genotype was 3.46 times higher than with T1M1 genotype (P=0.002; OR=3.46; CI=1.61-7.46). Moreover, the risk of developing LSCC cancer in people with T0M1 genotypes was significantly elevated (P=0.004; OR=4.5; CI=1.62-12.52). Conclusion: Unlike GSTM1, the GSTT1 genotype distribution is associated with the incidence of lung cancer in Iranian people. Different types of lung cancer appear to show various correlations with GST polymorphisms in this regard.

Lung cancer susceptibility from GSTM1 deletion and air pollution with smoking status: a meta-prediction of worldwide populations

Glutathione S transferase mu 1 (GSTM1) gene has been associated with lung cancer (LC) risk, for GSTM1 enzyme playing a vital role in detoxification pathway and protective against toxic insults. The major objective of this study was to investigate GSTM1 deletion pattern and its association with LC in the world’s population by using meta-prediction techniques. The secondary objective was to examine the effects of air pollution, smoking status, and other factors for gene-environment interactions with GSTM1 deletion and LC risk. We completed a comprehensive search to yield a total of 170 studies (40,296 cases and 48,346 controls) published from 1999 to 2017 for meta-analyses. The results revealed that GSTM1 deletion type was associated with increased risk of LC, while GSTM1 present type provided protective effect for all populations combined worldwide. Subgroup analysis on the rank order of risks from highest to lowest, among racial–ethnic groups, were Chinese, South East Asian, other North Asian, European, and finally American. Additional predictive analyses presented that air pollution played a significant role with increased risks of GSTM1 deletion and LC susceptibility, and the risks increased for smokers with higher levels of air pollution. Based on the findings of meta-predictive analysis, increased air pollution levels and smoking status presented additive effects to the LC risk susceptibilities and GSTM1 gene polymorphisms, for gene-environment interactions. Future studies are needed to examine gene-environment interactions for GSTM1 interacting with environmental factors and dietary interventions to mitigate the toxic effects, for LC prevention.

CYP2E1 and GSTM1 gene polymorphisms, environmental factors, and the susceptibility to lung cancer

OBJECTIVE

To investigate the relationships between the CYP2E1 RsaI polymorphism, GSTM1 polymorphism, and the susceptibility to lung cancer, along with the interactions between environmental factors and these genes.

METHODS

A case-control study was carried out to explore the independent effect of gene polymorphisms on risk of lung cancer, and the combined effects of gene loci. The stratification analysis of age, sex, smoking, and drinking combined with positive loci was also analyzed, and any interaction was identified.

RESULTS

The logistic regression analysis showed that there were statistical relationships between the CYP2E1 RsaI TT genotype and lung cancer, GSTM1 (-) and lung cancer. The combined effect's analysis of these 2 loci showed that, with an increase in the number of risk alleles, the risk of lung cancer also increased (supposing 0 risk allele as the reference group). Subjects carrying 3 risk alleles had the highest risk of developing lung cancer with an adjusted OR = 10.38 (95% CI 2.10-51.35). Stratified analysis showed that, in women, nonsmoking subjects, or nondrinking subjects, the combined effects could increase the risk of lung cancer; no heterogeneity was found between these layers except sex. The interaction analysis showed that, supposing the male, GSTM1 (+) genotype as the reference, the female, GSTM1 (-) genotype had a significantly increased risk of lung cancer (OR = 2.17 [1.01-4.70]); when the non-smoking, GSTM1 (+) genotype subjects was the reference group, smoking, GSTM1 (+) genotype subjects and smoking, GSTM1 (-) genotype subjects had significantly higher risk of lung cancer (OR = 2.00 [1.01-3.96], OR = 2.89 [1.28-6.54]).

CONCLUSION

CYP2E1 RsaI TT genotype was a protective factor against the development of lung cancer, while GSTM1 (-) genotype was a risk factor for lung cancer. Increases in the number of the risk alleles also increased lung cancer risk. GSTM1 (-) genotype, sex, and smoking status might interact in the incidence of lung cancer.

Reduced Expiratory Flow Rate among Heavy Smokers Increases Lung Cancer Risk. Results from the National Lung Screening Trial-American College of Radiology Imaging Network Cohort

RATIONALE

Although epidemiological studies consistently show that chronic obstructive pulmonary disease is associated with an increased risk of lung cancer, debate exists as to whether there is a linear relationship between the severity of airflow limitation and lung cancer risk.

OBJECTIVES

We examined this in a large, prospective study of older heavy smokers from the American College of Radiology Imaging Network subcohort of the National Lung Screening Trial (ACRIN). Airflow limitation was defined by prebronchodilator spirometry subgrouped according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades 1-4.

METHODS

In the National Lung Screening Trial-ACRIN cohort of 18,473 screening participants, 6,436 had airflow limitation (35%) and 12,037 (65%) had no airflow limitation. From these groups, 758 lung cancer cases were prospectively identified. Participants with airflow limitation were stratified according to GOLD groups 1 (n = 1,607), 2 (n = 3,528), 3 (n = 1,083), and 4 (n = 211). Lung cancer incidence at study end (mean follow-up, 6.4 yr) was compared between the GOLD groups and those with no airflow limitation (referent group).

MEASUREMENTS AND MAIN RESULTS

Compared with those with no airflow limitation, where lung cancer incidence was 3.78/1,000 person years, incidence rates increased in a simple linear relationship: GOLD 1 (6.27/1,000 person yr); GOLD 2 (7.86/1,000 person yr); GOLD 3 (10.71/1,000 person yr); and GOLD 4 (13.25/1,000 person yr). All relationships were significant versus the reference group at a P value of 0.0001 or less.

CONCLUSIONS

In a large prospective study of high-risk cigarette smokers, we report a strong linear relationship between increasing severity of airflow limitation and risk of lung cancer.

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

Objectives

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).

Materials and Methods

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.

Results

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).

Conclusion

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.

Phenotypic and genotypic characterization of antioxidant enzyme system in human population exposed to radiation from mobile towers

In the present era, cellular phones have changed the life style of human beings completely and have become an essential part of their lives. The number of cell phones and cell towers are increasing in spite of their disadvantages. These cell towers transmit radiation continuously without any interruption, so people living within 100s of meters from the tower receive 10,000 to 10,000,000 times stronger signal than required for mobile communication. In the present study, we have examined superoxide dismutase (SOD) enzyme activity, catalase (CAT) enzyme activity, lipid peroxidation assay, and effect of functional polymorphism of SOD and CAT antioxidant genes against mobile tower-induced oxidative stress in human population. From our results, we have found a significantly lower mean value of manganese superoxide dismutase (MnSOD) enzyme activity, catalase (CAT) enzyme activity, and a high value of lipid peroxidation assay in exposed as compared to control subjects. Polymorphisms in antioxidant MnSOD and CAT genes significantly contributed to its phenotype. In the current study, a significant association of genetic polymorphism of antioxidant genes with genetic damage has been observed in human population exposed to radiations emitted from mobile towers.

Concluding the trilogy: The interaction of 2,2'-dihydroxy-benzophenones and their carbonyl N-analogues with human glutathione transferase M1-1 face to face with the P1-1 and A1-1 isoenzymes involved in MDR

A series of 2,2'-dihydroxybenzophenones and their carbonyl N-analogues were studied as potential inhibitors against human glutathione transferase M1-1 (hGSTM1-1) purified from recombinant E. coli. Their screening revealed an inhibition against hGSTM1-1 within a range of 0-42% (25 μM). The IC₅₀ values for the two stronger ones, 16 and 13, were 53.5 ± 5.6 μΜ and 28.5 ± 2.5 μΜ, respectively. The results were compared with earlier ones for isoenzymes hGSTP1-1 and hGSTA1-1 involved in MDR. All but one bind more strongly to A1-1, than M1-1 and P1-1, the latter being a poor binder. An order of potency A1-1 > > M1-1 >  P1-1 meritted 13, 14 and 16 as the most potent inhibitors with hGSTM1-1. Enzyme kinetics with hGSTM1-1 (K_m(CDNB) 213 ± 10 μΜ and K_m(GSH) 303 ± 11 μΜ) revealed a competitive modality for 16 (K_i(16)  = 22.3 ± 1.1 μΜ) and a mixed one for 13 versus CDNB (K_i(13)  = 33.3 ± 1.6 μM for the free enzyme and K_i(13) ' = 17.7 ± 1.7 μM for the enzyme-CDNB complex). 5- or 5'-Bromo- or phenyl-substituted (but not in combination) inhibitors, having a H-bonded oxime weakly acidic group of a small volume, are optimal candidates for binding hGSTM1-1. The outcome of the isoenzyme trilogy identified good binder leads for the investigated GSTs involved in MDR.

Synergistic Association of CYP1A1 Polymorphisms with Increased Susceptibility to Squamous Cell Lung Cancer in North Indian Smokers

Objectives

Studies in different populations have shown that polymorphisms within the CYP1A1 gene play an important role in determining individual susceptibility to lung cancer. However, the data obtained so far have been contradictory within the same or different populations. Few studies have focused on the synergistic effect of CYP1A1 polymorphisms on the susceptibility to lung cancer overall and to different histological subtypes along with the impact of smoking.

Methods

A total of 704 individuals (353 lung cancer patients and 351 controls) were evaluated for CYP1A1 polymorphisms. CYP1A1 genotyping was done by means of PCR-RFLP.

Results

A CYP1A1 mutant genotype was found to be significantly associated with lung cancer (OR = 3.15; 95% CI = 1.75-5.71; p = 0.0001) and this risk was 4-fold higher in case of squamous cell carcinoma (SCC). The CYP1A1 m2 allelic variant was found to be strongly associated with the risk of SCC and adenocarcinoma. The combined “at risk” genotypes of the CYP1A1 m1 and m2 allelic variants were associated with lung cancer risk and this risk was higher in case of SCC (OR = 2.0; 95% CI = 1.97-3.81; p = 0.028). Furthermore, the lung cancer risk was associated with smoking, especially in heavy smokers carrying CYP1A1 variant genotypes. We also observed that heavy smokers with the mutant m1 genotype were at increased risk of SCC (OR = 5.4; 95% CI = 2.4-11.9; p<0.0001). Furthermore, when stratified for smoking dose and histology, the effect was compounded in heavy smokers and SCC (OR = 7.5; 95% CI = 1.8-30.9; p = 0.004).

Conclusions

Polymorphism in the CYP1A1 gene is an important risk modifier for lung cancer.

GSTM1 copy number variation in the context of single nucleotide polymorphisms in the human GSTM cluster

Background

GSTM1 gene deletion is one of the most known copy number polymorphisms in human genome. It is most likely caused by homologous recombination between the repeats flanking the gene. However, taking into account that the deletion has no crucial effects on human well-being, and the ability of other GSTMs to compensate for the lack of GSTM1, a role for additional factors affecting GSTM1 deletion can be proposed. Our goal was to explore the relationships between GSTM1 deletion polymorphism and single nucleotide polymorphisms (SNPs) in the region of the GSTM cluster that includes GSTM2, GSTM3, GSTM4, and GSTM5 in addition to GSTM1.

Results

Real-time polymerase chain reaction was used to quantify the number of GSTM1 copies. Fourteen SNPs from the region were tested and their allelic patterns were compared in groups of Russian individuals subdivided according to their GSTM1 deletion genotypes. Linkage disequilibrium-based haplotype analysis showed substantial differences of haplotype frequencies between the groups, especially between individuals with homozygous GSTM1 −/− and +/+ genotypes. Exploration of the results of phasing of GSTM1 and SNP genotypes revealed unequal segregation of GSTM1 + and − alleles at different haplotypes.

Conclusions

The observed differences in haplotype patterns suggest the potential role of genetic context in GSTM1 deletion frequency (appearance) and in the determination of the deletion-related effects.

Combined Effects of GSTM1 Null Allele and APOL1 Renal Risk Alleles in CKD Progression in the African American Study of Kidney Disease and Hypertension Trial

Apolipoprotein L-1 (APOL1) high-risk alleles and the glutathione-S-transferase-μ1 (GSTM1) null allele have been shown separately to associate with CKD progression in the African American Study of Kidney Disease and Hypertension (AASK) trial participants. Here, we determined combined effects of GSTM1 null and APOL1 high-risk alleles on clinical outcomes in 682 AASK participants who were classified into four groups by GSTM1 null or active genotype and APOL1 high- or low-risk genotype. We assessed survival differences among these groups by log-rank test and Cox regression adjusted for important clinical variables for time to GFR event (change in GFR of 50% or 25-ml/min per 1.73 m² decline), incident ESRD, death, or composite outcomes. The groups differed significantly in event-free survival for incident ESRD and composite outcomes (P≤0.001 by log-rank test). Compared with the reference GSTM1 active/APOL1 low-risk group, other groups had these hazard ratios for the composite outcome of incident ESRD and change in GFR: GSTM1 active/APOL1 high-risk hazard ratio, 2.13; 95% confidence interval, 0.76 to 5.90 (P=0.15); GSTM1 null/APOL1 low-risk hazard ratio, 2.05; 95% confidence interval, 1.08 to 3.88 (P=0.03); and GSTM1 null/APOL1 high-risk hazard ratio, 3.0; 95% confidence interval, 1.51 to 5.96 (P=0.002). In conclusion, GSTM1 null and APOL1 high-risk alleles deleteriously affect CKD progression among blacks with hypertension, and subjects with both GSTM1 null and APOL1 high-risk genotypes had highest risk of adverse renal outcomes. Larger cohorts are needed to fully explore interactions of GSTM1 and APOL1 genotypes in other subgroups.

GSTM1 and GSTT1 polymorphisms contribute to renal cell carcinoma risk: evidence from an updated meta-analysis

Emerging evidences suggest that GSTM1 and GSTT1 are involved in the detoxification of carcinogens, and polymorphisms in this gene that result in a loss of enzyme activity may increase the risk of renal cell carcinoma (RCC). Thus, to evaluate the association of GSTM1 and GSTT1 polymorphisms and RCC, we performed an updated meta-analysis of 10 case-control studies by RevMan 5.2, and the publication bias was tested using STATA 11.0. The meta-analysis showed that the single locus GSTM1 and GSTT1 polymorphisms were not significantly associated with a risk of RCC in a recessive model. However, that wild-type genotype versus the dual null genotype of GSTM1-GSTT1 showed a positive association with RCC risk (OR = 0.70; 95% CI = 0.51-0.98; P = 0.04). In another analysis of subjects exposed to pesticides, we found that the GSTM1 wild-type genotype was associated with increased RCC risk in Europeans (OR = 2.72; 95% CI = 1.54-4.82; P = 0.0006). We also identified an association between the GSTT1 wild-type and lower RCC TNM staging (I + II versus III + IV: OR = 1.88; 95% CI = 1.09-3.26; P = 0.02). This meta-analysis suggests that there may be a relationship between the GSTM1 and GSTT1 wild-type genotype and RCC.

Genetic polymorphisms in GSTM1, GSTT1 and GSTP1 genes and risk of lung cancer in a North Indian population

BACKGROUND

A number of studies done so far in different populations have shown that polymorphisms within the GST genes play an important role in determining individual susceptibility to lung cancer; however, data obtained so far have been contradictory within the same or different populations. Few studies have focused on the combinatorial effect of the GST genes on susceptibility to lung cancer and also for different histological subtypes. Our aim is to investigate the roles of GSTM1, GSTT1, and GSTP1 polymorphisms as genetic modifiers of risk for lung cancer and histological subtypes using a larger sample size in a North Indian population.

METHODS

In total 540 subjects (270 lung cancer cases and 270 controls) were evaluated for the GST polymorphism. Genotyping for the GSTM1, GSTT1 and GSTP1 gene was done by using a multiplex PCR and PCR-RFLP method.

RESULTS

GSTM1 null genotype was found to be associated with lung cancer (OR=1.65, 95%CI: 116-2.3, P=0.005) and this risk was higher in cases of adenocarcinoma (ADCC). GSTT1 and GSTP1 did not show any significant association with lung cancer; however, when stratified for histological subtypes a significant association was observed for ADCC and small-cell lung cancer (SCLC) for both GSTT1 null and variant GSTP1 genotypes. The combined 'at risk' genotypes of null GSTM1 and GSTT1 genes were found to be associated with lung cancer risk, and this risk was higher in cases of ADCC (OR=4.09, 95%CI: 110-10.2, P=0.002). There is a twofold increased risk for lung cancer with the null GSTM1 and wild-type GSTP1 genotypes (P=0.0004); similarly, a fourfold increased risk was observed with the null GSTT1 and wild-type GSTP1 genotypes (P=0.0001).

CONCLUSIONS

The deficient GST genotypes seem thus to be important risk modifiers for lung cancer and related histological subtypes, especially in combination.

Genetic susceptibility, residential radon, and lung cancer in a radon prone area

INTRODUCTION

Radon exposure has been classified as the second cause of lung cancer, after tobacco, and the first in never smokers. GSTM1 and GSTT1 genes deletion increase the risk of lung cancer. We aim to know whether the risk of lung cancer because of residential radon is modulated by these genetic polymorphisms.

METHODS

Hospital-based, case-control study where cases had confirmed lung cancer. Cases and controls did not have previous neoplasm and were older than 30. Controls attended hospital for noncomplex surgery. We analyzed the results for the whole sample and separately for never/light smokers and moderate/heavy smokers.

RESULTS

Seven-hundred and ninety-two participants were analyzed. GSTM1 and GSTT1 deletion conferred an odds ratio (OR) of 1.38 (95% confidence interval [CI] 0.93-2.04) and 1.13 (95% CI 0.70-1.82), respectively. Individuals with GSTM1 present and residential radon concentrations higher than 148 Bq/m had an OR of 1.48 (95% CI 0.73-3.00), whereas those with GSTM1 deleted had an OR of 2.64 (95% CI 1.18-5.91) when compared with participants with GSTM1 present and radon concentrations below 50 Bq/m3. Similar results were observed for GSTT1 deletion. These results were basically the same for the moderate/heavy smokers' subgroup.

CONCLUSIONS

The absence of GSTM1 and GSTT1 genes increases the risk of lung cancer because of radon exposure. These genes might modulate the carcinogenic pathway of alpha radiation. Further studies are warranted analyzing this association in never smokers.

CYP2E1 Rsa Ι/Pst Ι polymorphism and lung cancer susceptibility: a meta-analysis involving 10,947 subjects

Many studies have examined the association between the CYP2E1 Rsa Ι/Pst Ι (rs3813867) polymorphism gene polymorphisms and lung cancer risk in various populations, but their results have been inconsistent. The PubMed and CNKI database was searched for case–control studies published up to October 2013. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated. In this meta-analysis, we assessed 23 published studies involving comprising 4727 lung cancer cases and 6220 controls of the association between CYP2E1 Rsa Ι/Pst Ι polymorphism and lung cancer risk. For the homozygote c2/c2 and c2 allele carriers (c1/c2 + c2/c2), the pooled ORs for all studies were 0.73(95% CI = 0.62–0.84; P = 0.005 for heterogeneity) and 0.84 (95% CI = 0.77–0.92; P = 0.001 for heterogeneity) when compared with the homozygous wild-type genotype (c1/c1). In the stratified analysis by ethnicity, the same significantly risks were found among Asians and mixed population for both the c2 allele carriers and homozygote c2/c2. However, no significant associations were found in Caucasian population all genetic models. This updated meta-analysis suggests that CYP2E1 Rsa Ι/Pst Ι c2 allele is a decreased risk factor for the developing lung cancer among Asians and mixed population.

Oxidative stress and genetic markers of suboptimal antioxidant defense in the aging brain: a theoretical review

Normal aging involves a gradual breakdown of physiological processes that leads to a decline in cognitive functions and brain integrity, yet the onset and progression of decline are variable among older individuals. While many biological changes may contribute to this degree of variability, oxidative stress is a key mechanism of the aging process that can cause direct damage to cellular architecture within the brain. Oligodendrocytes are at a high risk for oxidative damage due to their role in myelin maintenance and production and limited repair mechanisms, suggesting that white matter may be particularly vulnerable to oxidative activity. Antioxidant defense enzymes within the brain, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione-S-transferase (GST), are crucial for breaking down the harmful end products of oxidative phosphorylation. Previous studies have revealed that allele variations of polymorphisms that encode these antioxidants are associated with abnormalities in SOD, CAT, GPx, and GST activity in the central nervous system. This review will focus on the role of oxidative stress in the aging brain and the impact of decreased antioxidant defense on brain integrity and cognitive function. Directions for future research investigations of antioxidant defense genes will also be discussed.

Genetic Contribution of Polymorphisms in Glutathione S-Transferases to Brain Tumor Risk

Existing data have shown a major effect of glutathione S-transferase (GST) single-nucleotide polymorphisms on activities of detoxification-related enzymes, and it is the functional importance that leads to extensive research on the association of GST polymorphisms with the risk of developing brain tumor. Previously reported associations, nevertheless, remain inconsistent. This study aimed to reevaluate the association with new information from recent research articles. We weekly searched multiple databases, aiming to cover all studies looking at the associations being examined in this work. Eligibility of studies was evaluated based on predesigned inclusion criteria. To assess the association of GST polymorphisms with brain tumor risk, we calculated genotypic ORs by comparing the number of genotypes between cases and controls. We also detected interstudy heterogeneity, publication bias, and single studies' influence. A total of 13 research articles were identified through databases and hand search. We found significantly elevated risk of brain tumor associated with GSTT1 null status in individuals of European ethnicity (OR 1.46, 95% CI 1.12-1.92). In the analysis of GSTP1 I105V, we observed that Val/Val genotype compared to the Ile/Ile genotype was more prone to a reduced brain tumor risk (OR 0.77, 95% CI 0.64-0.93). Such major effects were similarly seen for GSTP1 A114V (OR 1.14, 95% CI 1.01-1.29 for Val/Val + Ala/Val vs. Ala/Ala). When data were limited to glioma, we found a significant elevation associated with the combination of Val/Val and Ala/Val genotypes (OR 1.18, 95% CI 1.01-1.37). However, no clear association was detected between other polymorphisms investigated and glioma. These statistical data suggest that some of the polymorphisms at GST loci are possibly associated with the genetic risk of brain tumor.

Glutathione-S-transferase (GSTM1, GSTT1) null phenotypes and risk of lung cancer in a Korean population

PURPOSE

The aim of this study was to evaluate any association of GSTM1 and GSTT1 null genotypes with the risk of lung cancer in a South Korean population.

METHODS

We conducted a large-scale, population-based case-control study including 3,933 lung cancer cases and 1,699 controls. Genotypes of GSTM1 and GSTT1 were determined using real-time polymerase chain reaction.

RESULTS

In logistic regression analysis adjusted for age and smoking, we did not find any association between GSTM1 or GSTT1 and LC risk in women. However, in men, the GSTM1 and GSTTI null genotypes were borderline associated with risk (OR=1.18, 95% CI=0.99-1.41 for GSTM1, OR=1.18, 95% CI=0.99-1.41 for GSTT1), and combined GSTM1 and GSTT1 null genotypes conferred an increased risk for LC in men (OR=1.39, 95% CI=1.08-1.78). The OR for the GSTT1 null genotype was greater in subjects aged 55 years old or younger (OR=1.45, 95% CI=1.09-1.92 for men; OR=1.36, 95% CI=0.97-1.90 for women), than in those over age 55 (OR=1.03, 95% CI=0.83-1.27 for men; OR=0.86, 95% CI=0.66-1.12 for women) in both genders (p for interaction <0.05).

CONCLUSIONS

In the Korean population, the GSTM1 and GSTT1 null genotypes are risk factors for LC in men; the GSTT1 null genotype has a more prominent effect on LC risk in younger people (age 55 years and under) than in older individuals.

Genetic polymorphisms of phase I and phase II metabolic enzymes as modulators of lung cancer susceptibility

OBJECTIVES

Tobacco exposure remains the main etiologic factor for lung cancer (LC). Interactions between environment and individual genetic profile are particularly important for this disease. The aim of this study was to evaluate the contribution of CYP1A1*2A, CYP1A1*2C, CYP2D6*4, GSTP1, GSTM1, GSTT1 and NAT2 polymorphisms for the susceptibility to LC in a Portuguese population considering their demographic and clinical characteristics.

MATERIALS AND METHODS

A total of 200 LC and 247 controls subjects from the Centre of Portugal were studied. Clinical and demographic characteristics were collected from clinical files and by individual questionnaires. Polymorphisms of CYP1A1*2A, CYP1A1*2C, CYP2D6*4, GSTP1, GSTM1, GSTT1 and NAT2 were genotyped using PCR-RFLP, PCR multiplex, ARMS and real time.

RESULTS

Gender, family history of cancer, smoke cessation and alcohol consumption were independent risk factors (p < 0.05). Associations found between phases I and II genes and LC population reveal a sex dependent distribution. Logistic regression analysis demonstrates that enhanced activation by CYPs, associated by reduced or loss of function of phase II enzymes, can lead to a greater risk. GSTP1 and NAT2 polymorphisms studied have a significant contribution for the histological tumour types and the presence of metastases, at time of diagnosis, respectively, when males with smoking habits were considered.

CONCLUSION

Multiple interactions between environment and individual characteristics are clearly associated to this disease. Variants of the detoxification genes may act synergistically contributing to this disease and modifying the risk posed by smoking and sex. The GSTT1*0 and GSTP1 (Ile462Val) might contribute to the malignant phenotype through different mechanisms.

Glutathione S-transferase M1 and glutathione S-transferase T1 genotype in chronic pancreatitis: a meta-analysis

OBJECTIVE

A meta-analysis to determine the association between chronic pancreatitis and glutathione-S transferase (GST) mu 1 (GSTM1) and theta 1 (GSTT1) deletions.

METHODS

Case-control studies concerning the relationship between chronic pancreatitis and GSTM1 or GSTT1 deletions were identified (up to October 2013). Meta-analyses of the association between GSTM1 and GSTT1 genotype and chronic pancreatitis or alcoholic chronic pancreatitis (ACP) were performed.

RESULTS

Seven studies were included in the meta-analysis (650 patients/1382 controls for GSTM1 and 536 patients/1304 controls for GSTT1). There were no significant relationships between GSTM1/GSTT1 and chronic pancreatitis or GSTT1 and ACP. There was a significant association between GSTM1 null genotype and ACP (odds ratio 1.16, 95% confidence intervals 1.03, 1.30).

CONCLUSION

The GSTM1 null genotype was significantly associated with ACP risk.

Dual glutathione-S-transferase-θ1 and -μ1 gene deletions determine imatinib failure in chronic myeloid leukemia

Approximately 40% of patients with chronic myeloid leukemia (CML) receiving imatinib fail treatment. There is an increased risk of CML in subjects with (i) deletions of genes encoding glutathione-S-transferase (GST)-θ1 (GSTT1) and -μ1, (GSTM1) and (ii) the GST-π1 (GSTP1) single-nucleotide polymorphism (SNP) Ile105Val (GSTP1*B; rs1695); however, their effects on imatinib treatment outcome are not known. Here, we assess the role of these GSTs in relation to imatinib treatment outcome in 193 CML patients. Deletion of GSTT1 alone, or in combination with deletion of the GSTM1 gene, significantly increased the likelihood of imatinib failure (P = 0.021 and P < 0.001, respectively). The GSTP1*B SNP was not associated with time to imatinib failure. Losses of the GSTT1 and GSTM1 genes are therefore important determinants of imatinib failure in CML. Screening for GSTT1 and GSTM1 gene deletions during diagnosis may identify patients who may be better treated using an alternative therapy.

Cytoprotective and regulatory functions of glutathione S-transferases in cancer cell proliferation and cell death

PURPOSE

Glutathione S-transferases (GSTs) family of enzymes is best known for their cytoprotective role and their involvement in the development of anticancer drug resistance. Recently, emergence of non-detoxifying properties of GSTs has provided them with significant biological importance. Addressing the complex interactions of GSTs with regulatory kinases will help in understanding its precise role in tumor pathophysiology and in designing GST-centered anticancer strategies.

METHODS

We reviewed all published literature addressing the detoxification and regulatory roles of GSTs in the altered biology of cancer and evaluating novel agents targeting GSTs for cancer therapy.

RESULTS

The role of GSTs, especially glutathione S-transferase P1 isoform in tumoral drug resistance, has been the cause of intense debate. GSTs have been demonstrated to interact with different protein partners and modulate signaling pathways that control cell proliferation, differentiation and apoptosis. These specific functions of GSTs could lead to the development of new therapeutic approaches and to the identification of some interesting candidates for preclinical and clinical development. This review focuses on the crucial role played by GSTs in the development of resistance to anticancer agents and the major findings regarding the different modes of action of GSTs to regulate cell signaling.

The associations between two vital GSTs genetic polymorphisms and lung cancer risk in the Chinese population: evidence from 71 studies

BACKGROUND

The genetic polymorphisms of glutathione S-transferase (GSTs) have been suspected to be related to the development of lung cancer while the current results are conflicting, especially in the Chinese population.

METHODS

Data on genetic polymorphisms of glutathione S-transferase Mu 1 (GSTM1) from 68 studies, glutathione S-transferase theta 1 (GSTT1) from 17 studies and GSTM1-GSTT1 from 8 studies in the Chinese population were reanalyzed on their association with lung cancer risk. Odds ratios (OR) were pooled using forest plots. 9 subgroups were all or partly performed in the subgroup analyses. The Galbraith plot was used to identify the heterogeneous records. Potential publication biases were detected by Begg's and Egger's tests.

RESULTS

71 eligible studies were identified after screening of 1608 articles. The increased association between two vital GSTs genetic polymorphisms and lung cancer risk was detected by random-effects model based on a comparable heterogeneity. Subgroup analysis showed a significant relationship between squamous carcinoma (SC), adenocarcinoma (AC) or small cell lung carcinoma (SCLC) and GSTM1 null genotype, as well as SC or AC and GSTT1 null genotype. Additionally, smokers with GSTM1 null genotype had a higher lung cancer risk than non-smokers. Our cumulative meta-analysis demonstrated a stable and reliable result of the relationship between GSTM1 null genotype and lung cancer risk. After the possible heterogeneous articles were omitted, the adjusted risk of GSTs and lung cancer susceptibility increased (fixed-effects model: ORGSTM1 = 1.23, 95% CI: 1.19 to 1.27, P<0.001; ORGSTT1 = 1.18, 95% CI: 1.10 to 1.26, P<0.001; ORGSTM1-GSTT1 = 1.33, 95% CI: 1.10 to 1.61, P = 0.004).

CONCLUSIONS

An increased risk of lung cancer with GSTM1 and GSTT1 null genotype, especially with dual null genotype, was found in the Chinese population. In addition, special histopathological classification of lung cancers and a wide range of gene-environment and gene-gene interaction analysis should be taken into consideration in future studies.

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.

Functional compensation of glutathione S-transferase M1 (GSTM1) null by another GST superfamily member, GSTM2

The gene for glutathione-S-transferase (GST) M1 (GSTM1), a member of the GST-superfamily, is widely studied in cancer risk with regard to the homozygous deletion of the gene (GSTM1 null), leading to a lack of corresponding enzymatic activity. Many of these studies have reported inconsistent findings regarding its association with cancer risk. Therefore, we employed in silico, in vitro, and in vivo approaches to investigate whether the absence of a functional GSTM1 enzyme in a null variant can be compensated for by other family members. Through the in silico approach, we identified maximum structural homology between GSTM1 and GSTM2. Total plasma GST enzymatic activity was similar in recruited individuals, irrespective of their GSTM1 genotype (positive/null). Furthermore, expression profiling using real-time PCR, western blotting, and GSTM2 overexpression following transient knockdown of GSTM1 in HeLa cells confirmed that the absence of GSTM1 activity can be compensated for by the overexpression of GSTM2.

CYP1A1 gene polymorphisms and smoking status as modifier factors for lung cancer risk

OBJECTIVE

Lung cancer remains the most prevalent malignancy worldwide. Susceptibility to lung cancer has been shown to be modulated by inheritance of polymorphic genes. Several metabolic enzymes are currently under investigation for their possible role in lung cancer susceptibility, including members of the cytochrome P450 (CYP) superfamily. The aim of this work was to identify the correlation between CYP1A1 m1 and m2 polymorphisms and lung cancer risk and figure its interactions with smoking as genetic modifiers in the etiology of lung cancer in the Egyptian population.

MATERIALS AND METHODS

One hundred and ten patients with lung cancer and one hundred and ten controls were enrolled in the study. CYP1A1 m1 and m2 polymorphisms were determined using polymerase chain reaction restriction fragment length polymorphism.

RESULTS

Subjects carrying TC and CC genotypes of CYP1A1 m1 and AG and GG genotypes of CYP1A1 m2 were significantly more likely to develop lung cancer especially squamous cell carcinoma. The proportion of lung cancer attributable to the interaction of smoking and CYP1A1 m1 and CYP1A1 m2 polymorphisms was 32% and 52% respectively.

CONCLUSION

Our results revealed that CYP1A1 m1 and m2 polymorphisms contribute to smoking related lung cancer risk in the Egyptian population.

Role of chronic obstructive pulmonary disease in lung cancer pathogenesis

Chronic obstructive pulmonary disease (COPD) and lung cancer are two important smoking related conditions. However, COPD has been shown to be an independent risk factor for lung cancer regardless of smoking history, suggesting that COPD and lung cancer may share a common pathogenesis. This review summarizes the epidemiology of lung cancer and COPD briefly, as well as discussing the potential for shared genetic risk, and shared genomic mechanisms, such as epigenetic changes or DNA damage induced by smoking. How key areas of COPD pathogenesis, such as inflammation, oxidative stress and protease imbalance may contribute to subsequent development of cancer will also be covered. Finally the possibility that consequences of COPD, such as hypoxia, influence carcinogenesis will be reviewed. By understanding the pathogenesis of COPD and lung cancer in detail it is possible that new treatments may be developed and the risk of lung cancer in COPD may be reduced.

Association of the glutathione s-transferase m1, t1 polymorphisms with cancer: evidence from a meta-analysis

BACKGROUND

Glutathione S-transferases (GSTs) are a family of multifunctional enzymes that are involved in the metabolism of many xenobiotics, including a wide range of environmental carcinogens. While the null genotypes in GSTM1 and GSTT1 have been implicated in tumorigenesis, it remains inconsistent and inconclusive. Herein, we aimed to assess the possible associations of the GSTM1 and GSTT1 null genotype in cancer risks.

METHODS

A meta-analysis based on 506 case-control studies was performed. Odds ratios (OR) with corresponding 95% confidence intervals (CIs) were used to assess the association.

RESULTS

The null genotypes of GSTM1 and GSTT1 polymorphisms were associated with a significantly increased risk in cancer (for GSTM1: OR = 1.17; 95%CI = 1.14-1.21; for GSTT1: OR = 1.16; 95%CI = 1.11-1.21, respectively). When the analysis was performed based on their smoking history, the risk associated of GSTM1 null and GSTT1 null genotypes with cancer is further increased (for GSTM1: OR = 2.66; 95%CI = 2.19-3.24; for GSTT1: OR = 2.46; 95%CI = 1.83-3.32, respectively).

CONCLUSIONS

These findings indicate that GSTM1 and GSTT1 polymorphisms may play critical roles in the development of cancer, especially in smokers.

DNA adducts and combinations of multiple lung cancer at-risk alleles in environmentally exposed and smoking subjects

Interindividual variation in DNA adduct levels in individuals exposed to similar amounts of environmental carcinogens may be due to genetic variability. We analysed the influence of genes involved in determining/modifying DNA damage, including microsomal epoxide hydrolase1 (EPHX1) His139Arg, N-acetyl-transferase, NAD(P)H:quinone oxidoreductase1 (NQO1) Pro187Ser, manganese superoxide dismutase2 (MnSOD2) Val16Ala, and apurinic/apyrimidinic endonuclease1 (APE1) Asp148Glu polymorphisms in blood of 120 smokers. Subsequently, we examined the effects of the combinations of the variant alleles of EPHX, NQO1 and MnSOD2 together with the wild type allele of APE1 on DNA damage by calculating the "sum of at-risk alleles." We reviewed the studies examining the relationships of DNA adducts with at-risk alleles in environmentally exposed subjects. Our findings showed that smokers carrying the EPHX1-139Arg and the NQO1-187Ser variants were significantly more likely to have higher adduct levels. Null associations were found with the other variants. Nevertheless, DNA adduct levels in smokers with ≥5 at-risk alleles were significantly different from those with fewer than two alleles. A similar picture emerged from studies of DNA adducts and at-risk alleles in environmentally exposed and smoking subjects. Certain at-risk allele combinations may confer a greater likelihood of increased levels of adducts after environmental insults. The increase in DNA adduct levels in susceptible subjects exposed to environmental carcinogens may reflect changes in the mechanisms that protect cells from the accumulation of genetic damage. Alterations of the physiological processes designed to maintain homeostasis may reduce the individual "genotoxic tolerance" to environmental challenges and result in phenotypes characterized by high levels of DNA adducts.

CCND1 G870A polymorphism interaction with cigarette smoking increases lung cancer risk: meta-analyses based on 5008 cases and 5214 controls

Evidence indicates CCND1 G870A polymorphisms as a risk factor for a number of cancers. Increasing studies have been conducted on the association of CCND1 G870A polymorphism with lung cancer risk. However, the results were controversial. The aim of the present study was to derive a more precise estimation of the relationship. Meta-analyses examining the association between CCND1 G870A polymorphism and lung cancer were performed. Subgroup analyses regarding ethnicity, smoking status, histological types and source of controls were also implemented. All eligible studies for the period up to May 2012 were identified. The overall data from ten case-control studies including 5,008 cases and 5,214 controls indicated that variant A allele may have an association with increased lung cancer risk (AA vs GG: OR = 1.21; 95 % CI = 1.08-1.36, dominant model: OR = 1.09; 95 % CI = 1.00-1.19, recessive model: OR = 1.23; 95 % CI = 1.01-1.49). In the subgroup analysis by ethnicity, A allele may elevate lung cancer risk among Asians but not Caucasians or Mixed ethnicities. In smoking status subgroup, A allele was shown to associate with increased lung cancer risk among smokers but not non-smokers. In the subgroup analysis by histological types, increased cancer risks were shown in adenocarcinoma but not squamous cell carcinoma, under the homozygote comparison and recessive models. Collectively, the results of the present study suggest that CCND1 G870A polymorphism might be a low-penetrant risk factor for lung cancer, particularly among Asians and smokers. Moreover, homozygous AA alleles might have a correlation with increased lung adenocarcinoma susceptibility.

Association between the polymorphisms of glutathione S-transferase genes and rheumatoid arthritis: a meta-analysis

The glutathione S-transferases (GSTs) are a family of phase II xenobiotic metabolizing enzymes known to be involved in the detoxification and elimination of reactive oxygen species (ROS), thus defending tissues against oxidative stress. Recently, several studies have examined the potential contributions of GSTM1 and GSTT1 gene polymorphisms toward susceptibility to rheumatoid arthritis (RA), but these studies have produced diverse results. To verify the association between GSTM1 and GSTT1 gene polymorphisms and susceptibility to RA, we conducted a meta-analysis of all relevant reports cited in MEDLINE/PubMed before April 2012. A meta-analysis on the association between the GSTM1 polymorphism and RA was performed for 4636 patients with RA and 3916 controls from 8 published studies. In addition, a total of 5 studies involving 3174 RA patients and 2958 controls were considered in the meta-analysis of the association between the GSTT1 polymorphism and RA. No significant association was found between the GSTM1 null genotype and RA susceptibility in all subjects; however, a significant increased risk was found in East Asians. The GSTT1 null genotype was not associated with susceptibility to RA in any study subject. No apparent effect of smoking was found in stratified analysis. The results of our meta-analysis indicated that the GSTM1 null genotype is significantly associated with RA in East Asians alone, indicating that GSTM1 is another non-human leukocyte antigen (non-HLA) susceptibility gene for RA in East Asian populations.

Genetic susceptibility to lung cancer--light at the end of the tunnel?

Lung cancer is one of the most common and deadliest cancers in the world. The major socio-environmental risk factor involved in the development of lung cancer is cigarette smoking. Additionally, there are multiple genetic factors, which may also play a role in lung cancer risk. Early work focused on the presence of relatively prevalent but low-penetrance alterations in candidate genes leading to increased risk of lung cancer. Development of new technologies such as genomic profiling and genome-wide association studies has been helpful in the detection of new genetic variants likely involved in lung cancer risk. In this review, we discuss the role of multiple genetic variants and review their putative role in the risk of lung cancer. Identifying genetic biomarkers and patterns of genetic risk may be useful in the earlier detection and treatment of lung cancer patients.

Asthmatic airway neutrophilia after allergen challenge is associated with the glutathione S-transferase M1 genotype

RATIONALE

Asthma is a heterogeneous lung disorder characterized by airway inflammation and airway dysfunction, manifesting as hyperresponsiveness and obstruction. Glutathione S-transferase M1 (GSTM1) is a multifunctional phase II enzyme and regulator of stress-activated cellular signaling relevant to asthma pathobiology. A common homozygous deletion polymorphism of the GSTM1 gene eliminates enzyme activity.

OBJECTIVES

To determine the effect of GSTM1 on airway inflammation and reactivity in adults with established atopic asthma in vivo.

METHODS

Nineteen GSTM1 wild-type and eighteen GSTM1-null individuals with mild atopic asthma underwent methacholine and inhaled allergen challenges, and endobronchial allergen provocations through a bronchoscope.

MEASUREMENTS AND MAIN RESULTS

The influx of inflammatory cells, panels of cytokines and chemokines linked to asthmatic inflammation, F(2)-isoprostanes (markers of oxidative stress), and IgE were measured in bronchoalveolar lavage fluid at baseline and 24 hours after allergen instillation. Individuals with asthma with the GSTM1 wild-type genotype had greater baseline and allergen-provoked airway neutrophilia and concentrations of myeloperoxidase than GSTM1-null patients. In contrast, the eosinophilic inflammation was unaffected by GSTM1. The allergen-stimulated generation of acute-stress and proneutrophilic mediators, tumor necrosis factor-α, CXCL-8, IL-1β, and IL-6, was also greater in the GSTM1 wild-type patients. Moreover, post-allergen airway concentrations of IgE and neutrophil-generated mediators, matrix metalloproteinase-9, B-cell activating factor, transforming growth factor-β1, and elastase were higher in GSTM1 wild-type individuals with asthma. Total airway IgE correlated with B-cell activating factor concentrations. In contrast, levels of F(2)-isoprostane were comparable in both groups. Finally, GSTM1 wild-type individuals with asthma required lower threshold concentrations of allergen to produce bronchoconstriction.

CONCLUSIONS

The functional GSTM1 genotype promotes neutrophilic airway inflammation in humans with atopic asthma in vivo.