The human glutathione S-transferase supergene family, its polymorphism, and its effects on susceptibility to lung cancer

Glutathione S-transferase M1, T1, and P1 polymorphisms and periodontitis in a Caucasian population: a case-control study

BACKGROUND

Glutathione S-transferases (GSTs) play important roles in protecting cells against oxidative stress and toxic chemicals. This study aimed to investigate the distribution of GSTM1, GSTT1, and GSTP1 variants and their roles in periodontitis susceptibility in a Caucasian population.

METHODS

We analyzed 406 participants, including 204 healthy controls and 203 periodontitis patients. A multiplex polymerase chain reaction (PCR) approach was used to analyze GSTM1 and GSTT1 loci. GSTP1 variants were detected by PCR-haplotyping method in a subgroup of participants (N = 350). Chi-square or Fisher´s exact tests were used to compare genotypic and allelic differences. The Bonferroni method was applied to correct for multiple comparisons (pcorr).

RESULTS

The GSTM1 genotype distribution did not differ significantly between controls and periodontitis patients (p = 0.44). Additionally, the wild/null genotypes of GSTT1, Ile105Val and Ala114Val frequencies of GSTP1 were not significantly different between the two groups after correction for multiple comparisons (p = 0.05, p = 0.55, p = 0.02, pcorr>0.05, respectively). The GSTM1 and GSTP1 Ile105Val gene variants were similarly distributed between non-smokers and smokers in both groups (p = 0.38, p = 0.20, and p = 0.14, p = 0.35, respectively). However, the wild genotype of the GSTT1 and Ala114Ala variant of the GSTP1 genes were present more frequently in non-smoking periodontitis patients than in non-smoking controls (p = 0.03, pcorr>0.05, and p = 0.009, pcorr>0.05, respectively) although their frequencies did not differ between smoking periodontitis patients and smoking controls (p = 0.23, p = 0.68, respectively).

CONCLUSIONS

This study in a Czech Caucasian population did not confirm a highly significant association between GST gene variants and susceptibility to periodontitis, as previously reported by Arshad and colleagues in Pakistanis. However, a weak relationship between GSTT1 and GSTP1 rs1138272 polymorphisms and periodontitis in non-smokers was observed.

Passive smoking and insomnia in rural Chinese nonsmoking housewives: An environmental and genetic perspective

Active smoking has been a risk factor for insomnia, however, little is known about the effect of passive smoking on insomnia. Polycyclic aromatic hydrocarbons (PAHs) are potential contents in tobacco smoke. We aimed to investigate the association between passive smoking exposure and insomnia, plus the modification effects of single nucleotide polymorphisms (SNPs) related to PAHs metabolism. A cross-sectional study with 392 nonsmoking women was conducted in a rural area of Shanxi Province, China. A structured questionnaire was used to collect the information on passive smoking exposure, insomnia and other health-related factors via face-to-face interviews. We simultaneously collected participants' hair samples to measure the concentrations of 26 PAHs. Whole blood samples were collected to test 9 SNPs related to PAHs metabolism. Logistic regression analysis was conducted to evaluate the association between passive smoking and insomnia, as well as the relation between passive smoking and PAHs concentrations. We further examined the potential interaction effects between passive smoking and SNPs on insomnia. 118 (30.1 %) were exposed to passive smoking and 128 (32.7 %) suffered from insomnia. Passive smoking nearly doubled the probability of insomnia with adjusted odds ratio and 95 % confidence interval of (1.99: 1.16, 3.39). Dose-response association between passive smoking and insomnia was observed by passive smoking frequency (P trend < 0.001). Among the 7 PAHs measured with detection rates > 70 %, no specific PAH was detected to be associated with passive smoking exposure after Bonferroni correction. The mutant genotypes of CYP1B1 (rs1056836), AHR (rs2066853), and AHRR (rs2292596) were detected to have synergetic effects with passive smoking on insomnia after multivariate adjustment. We found a positive association between passive smoking status and insomnia among nonsmoking women. This association could be modified by SNPs related to PAHs metabolism. PAHs might not be the environmentally potential mechanism involved in the insomnia caused by tobacco smoke exposure.

Glutathione S-transferases and their implications in the lung diseases asthma and chronic obstructive pulmonary disease: Early life susceptibility?

Our lungs are exposed daily to airborne pollutants, particulate matter, pathogens as well as lung allergens and irritants. Exposure to these substances can lead to inflammatory responses and may induce endogenous oxidant production, which can cause chronic inflammation, tissue damage and remodeling. Notably, the development of asthma and Chronic Obstructive Pulmonary Disease (COPD) is linked to the aforementioned irritants. Some inhaled foreign chemical compounds are rapidly absorbed and processed by phase I and II enzyme systems critical in the detoxification of xenobiotics including the glutathione-conjugating enzymes Glutathione S-transferases (GSTs). GSTs, and in particular genetic variants of GSTs that alter their activities, have been found to be implicated in the susceptibility to and progression of these lung diseases. Beyond their roles in phase II metabolism, evidence suggests that GSTs are also important mediators of normal lung growth. Therefore, the contribution of GSTs to the development of lung diseases in adults may already start in utero, and continues through infancy, childhood, and adult life. GSTs are also known to scavenge oxidants and affect signaling pathways by protein-protein interaction. Moreover, GSTs regulate reversible oxidative post-translational modifications of proteins, known as protein S-glutathionylation. Therefore, GSTs display an array of functions that impact the pathogenesis of asthma and COPD.

In this review we will provide an overview of the specific functions of each class of mammalian cytosolic GSTs. This is followed by a comprehensive analysis of their expression profiles in the lung in healthy subjects, as well as alterations that have been described in (epithelial cells of) asthmatics and COPD patients. Particular emphasis is placed on the emerging evidence of the regulatory properties of GSTs beyond detoxification and their contribution to (un)healthy lungs throughout life. By providing a more thorough understanding, tailored therapeutic strategies can be designed to affect specific functions of particular GSTs.

The Relation between Polymorphisms in Exon 5 and Exon 6 of GSTP1 Gene and the Risk of Lung Cancer in Iranian People

Objective:

The GSTP1 gene, which is located on chromosome 11q13, consists of 7 exons and 6 introns. There are two polymorphisms in GSTP1 that have been exposed to a transposition for codon 105 (Ile/Val) and 114 (Ala/Val) in exons 5 and 6, which have been studied previously in relation to lung cancer. Since the level of GSTP1 expression in lung tissues and other human epithelial tissues is high, GSTP1Val-105 polymorphism is recognized as a sensitive factor for tobacco-related cancers, especially lung cancer.

Methods:

One hundred and twenty tissue block samples of patients with lung cancers and 120 peripheral blood samples of the control group were obtained from two referral cancer centers in Tehran, Iran, from 2011 to 2016. Genomic DNA was extracted from tissue blocks and buffy coat of study cases to detect SNP of GSTP1 gene using Tetra-primer ARMS-PCR.

Results:

There was a notable correlation between the incidence of lung cancer and variant Val105 (P-value=0.001; OR=2/6; 95% CI=1.49-4.53) and Ile105 (P-value=0.003; OR=0.41; 95% CI=0.23-0.73). The odds ratio for lung cancer in the homozygous Ile105/Ile105 genotype was 3.56 times higher than that of individual with heterozygous Ile105/Val105 (P-value<0.001; OR=3/56; 95% CI=1.826-6.934) genotype, that was statistically significant. Furthermore, the results showed that there was no significant correlation between Ala114/Val114 genotypes and lung cancer. The BC (P-value=0.007; OR=0.16; 95% CI=0.04-0.61) and AA (P=0.001) genotypes were statistically significant (P-value <0.05); and for those who had AA genotype, the odds ratio was almost six times higher than those with BC genotype.

Conclusions:

The study of GSTP1 polymorphisms indicated that unlike the polymorphism in exon 5, the GSTP1 exon 6 polymorphism correlated with the lung cancer risk in the select group of Iranian people. Likewise, the potential use of this genetic polymorphism as a lung cancer predictor is confirmed.

GSTM1 and GSTT1 Genetic Polymorphisms and Breast Cancer Risk in Selected Filipino Cases

Background:

The association of genetic polymorphisms with cancer development has been shown to be race- and tumor site-specific. Thus, this study aimed to determine whether polymorphisms in the GSTM1 and GSTT1 genes are associated with breast cancer among selected Filipinos.

Methods:

A total of 136 histologically confirmed breast cancer cases were age- and sex-matched with 136 clinically healthy controls. Genomic DNA extracted from blood samples of participants were screened for GSTM1 and GSTT1 genetic polymorphisms by multiplex PCR.

Results:

The frequency of null genotypes among the cases (GSTM1: n=78; 57.4%; GSTT1: n=61; 44.9%) was not significantly different (p>0.05) from the controls (GSTM1: n=93; 68.4%; GSTT1: n=59; 43.4%). It was also demonstrated that risk for breast cancer was increased in passive smokers carrying the GSTM1 null (OR=2.56; 95% CI=1.38-4.75) or GSTT1 positive (OR=2.00; 95% CI=1.05-3.83) genotypes. Moreover, risk was decreased in alcohol users carrying the GSTT1 null (OR=0.39; 95% CI=0.16-0.97) genotype

. Conclusion:

This study suggests that variants of GSTM1 and GSTT1 may not be risk factors for breast cancer development among Filipinos. However, the risk may be increased when these genotypes were combined with lifestyle or environmental factors.

Passive smoking and influenza-like illness in housewives: A perspective of gene susceptibility

Relation between influenza-like illness (ILI) and passive smoking remains a debate of subject. We aimed to determine an association of passive smoking with ILI risk of housewives in North China, and the modification effects of gene polymorphisms related to the metabolisms of smoking pollutants. We included 379 housewives for a cross-sectional study in Shanxi Province, China, including 118 with ILI frequency of "≥1 times per year" as the case group and 261 with ILI frequency of "<1 time per year" in the past 10 years as the control group. We collected their information on frequencies of passive smoking and ILI by questionnaires, as well as their single nucleotide polymorphisms (SNPs) of genes related to Phase I and Phase II metabolisms of smoking pollutants. Our results revealed a significant Spearman correlation between frequencies of ILI and passive smoking (r = 0.406, p < 0.001). Frequency of passive smoking was associated with an increased risk of ILI with adjusted OR [6.75 (95% confidence interval: 3.98-11.4)]. Dose-response association between the passive smoking and ILI risk was observed with or without adjusting for confounders. Mutant types of rs1041983 (N-acetyltransferase 2 gene, NAT2) had a synergetic effect with passive smoking on ILI frequency, while mutant types of rs1695 (glutathione S-transferase P1 gene, GSTP1) had an antagonistic effect. Overall, our study results supported the hypothesis that passive smoking was positively associated with ILI frequency in housewives and this effect was modified by gene polymorphisms of Phase II metabolism genes (NAT2 and GSTP1).

Combined Genetic Biomarkers Confer Susceptibility to Risk of Urothelial Bladder Carcinoma in a Saudi Population

We evaluated the associations between seven single nucleotide polymorphisms and susceptibility to urothelial bladder carcinoma (UBC) in a Saudi population. Genomic DNA was taken from buccal cells of 52 patients with UBC and 104 controls for genotyping of GSTT1, GSTM1, rs4646903, rs1048943, TP53 rs1042522, rs1801133, and rs1801394 using PCR and TaqMan® assays. The rs1801133 and rs1801394 variants showed strong associations with UBC (OR = 2.3, P = 0.0002; OR = 2.6, P = 0.0001, resp.). Homozygosity of Pro72 conferred a significant double risk in cases compared with controls (30.8% versus 15.4%), but the homozygote Arg/Arg had no effect on risk. Genotypic combinations of GSTM1/GSTT1, rs4646903/rs1048943, and rs1801133/rs1801394 exhibited significant linkage with the disease (χ² = 10.3, P = 0.006; χ² = 13.9, P = 0.003; and χ² = 20.4, P = 0.0004, resp.). The GSTM1 and rs1042522Arg and rs1801394G variant alleles were more frequent in current smokers with UBC (52.4%, 52.5%, and 64.3%, resp.) than were the corresponding wild-types. Despite some variants having only a slight effect on UBC risk, the interaction effect of combined genetic biomarkers-or even the presence of one copy of a variant allele-is potentially much greater. Perhaps more studies regarding next-generation genetic sequencing and its utility can add to the risk of UBC.

Effects of different mycotoxins on humans, cell genome and their involvement in cancer (Review)

The chemical nature of most of the mycotoxins makes them highly liposoluble compounds that can be absorbed from the site of exposure such as from the gastrointestinal and respiratory tract to the blood stream where it can be dissimilated throughout the body and reach different organs such as the liver and kidneys. Mycotoxins have a strong tendency and ability to penetrate the human and animal cells and reach the cellular genome where it causes a major mutagenic change in the nucleotide sequence which leads to strong and permanent defects in the genome. This defect will eventually be transcribed, translated and lead to the development of cancer. In this review, the chemical and physical nature of mycotoxins, the action of mycotoxins on the cellular genome and its effect on humans, mycotoxins and their carcinogenicity and mycotoxins research gaps are discussed, and new research areas are suggested. The research review posed various questions. What are the different mycotoxins that can cause cancer, what is the role of mycotoxins in causing cancer and what types of cancers can be caused by mycotoxins? These questions have been selected due to the significant increase in the mycotoxin contamination and the cancer incidence rate in the contemporary world. By revealing and understanding the role of mycotoxins in developing cancer, measures to reduce the risks and incidents of cancer could be taken.

Combined Genetic Biomarkers Confer Susceptibility to Risk of Urothelial Bladder Carcinoma in a Saudi Population

We evaluated the associations between seven single nucleotide polymorphisms and susceptibility to urothelial bladder carcinoma (UBC) in a Saudi population. Genomic DNA was taken from buccal cells of 52 patients with UBC and 104 controls for genotyping of GSTT1, GSTM1, rs4646903, rs1048943, TP53 rs1042522, rs1801133, and rs1801394 using PCR and TaqMan® assays. The rs1801133 and rs1801394 variants showed strong associations with UBC (OR = 2.3, P = 0.0002; OR = 2.6, P = 0.0001, resp.). Homozygosity of Pro72 conferred a significant double risk in cases compared with controls (30.8% versus 15.4%), but the homozygote Arg/Arg had no effect on risk. Genotypic combinations of GSTM1/GSTT1, rs4646903/rs1048943, and rs1801133/rs1801394 exhibited significant linkage with the disease (χ² = 10.3, P = 0.006; χ² = 13.9, P = 0.003; and χ² = 20.4, P = 0.0004, resp.). The GSTM1 and rs1042522Arg and rs1801394G variant alleles were more frequent in current smokers with UBC (52.4%, 52.5%, and 64.3%, resp.) than were the corresponding wild-types. Despite some variants having only a slight effect on UBC risk, the interaction effect of combined genetic biomarkers-or even the presence of one copy of a variant allele-is potentially much greater. Perhaps more studies regarding next-generation genetic sequencing and its utility can add to the risk of UBC.

Association of indoor air pollution from coal combustion with influenza-like illness in housewives

An association of influenza-like illness (ILI) with outdoor air pollution has been reported. However, the effect of indoor air pollution on ILI was rarely investigated. We aimed to determine an association of indoor air pollution from coal combustion (IAPCC) and lifestyle with ILI risk in housewives, and the modification effect of phase II metabolic enzyme genes. We recruited 403 housewives for a cross-sectional study in Shanxi Province, China, including 135 with ILI frequency (≥1 time per year in the past ten years) as the case group and 268 with ILI frequency (<1 times per year) as the control group. Information on their energy usage characteristics and lifestyle was collected by questionnaires, as well as the single nucleotide polymorphisms (SNPs) of epoxide hydrolase 1 (rs1051740 and rs2234922), N-acetyltransferase 2 (rs1041983), and glutathione S-transferase (rs1695). We used exposure index to indicate the level of IAPCC among housewives. Our results revealed that the exposure index was positively correlated with ILI frequency. A significant dose-response trend between the exposure index and ILI risk was found with or without adjusting for confounders. Cooking frequency in kitchen with coal as primary fuel and ventilation frequency in the living room or bedroom with a coal-fueled stove for heating during the heating season were two important risk factors to affect ILI frequency. Only rs1051740 was found to be associated with exposure index, whereas it didn't have interaction effect with exposure index on ILI frequency. In conclusion, IAPCC and SNPs of rs1051740 were both associated with ILI frequency.

Association of polycyclic aromatic hydrocarbons in housewives' hair with hypertension

The relationship between polycyclic aromatic hydrocarbons (PAHs) and hypertension remains a subject of debate. The aims of this study were to determine an association of concentrations of PAHs in housewives' hair with hypertension risk and the modification effect of single nucleotide polymorphisms (SNPs) related to Phase I metabolism of PAHs. We recruited 405 women for a cross-sectional study in Shanxi Province, China, including 170 with hypertension (the case group) and 235 without hypertension (the control group). We analyzed 26 individual PAHs in hair samples and the SNPs of the genes including cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1), CYP1A2, CYP1B1 and CYP2E1. Our results showed that seven PAHs in hair samples were measured with detection rate >70%. Only acenaphthylene was found to be associated with an increased risk of hypertension with adjustment for the potential confounders following Bonferroni correction, whereas others not. No SNPs of the concerned genes were found to be associated with the risk of hypertension. A multiple interaction effect of PAHs in housewives' hair and SNPs on hypertension risk was not observed. It was concluded that PAHs tended to contribute to the formation of hypertension.

Polycyclic aromatic hydrocarbons: from metabolism to lung cancer

Excessive exposure to polycyclic aromatic hydrocarbons (PAHs) often results in lung cancer, a disease with the highest cancer mortality in the United States. After entry into the lung, PAHs induce phase I metabolic enzymes such as cytochrome P450 (CYP) monooxygenases, i.e. CYP1A1/2 and 1B1, and phase II enzymes such as glutathione S-transferases, UDP glucuronyl transferases, NADPH quinone oxidoreductases (NQOs), aldo-keto reductases (AKRs), and epoxide hydrolases (EHs), via the aryl hydrocarbon receptor (AhR)-dependent and independent pathways. Humans can also be exposed to PAHs through diet, via consumption of charcoal broiled foods. Metabolism of PAHs through the CYP1A1/1B1/EH pathway, CYP peroxidase pathway, and AKR pathway leads to the formation of the active carcinogens diol-epoxides, radical cations, and o-quinones. These reactive metabolites produce DNA adducts, resulting in DNA mutations, alteration of gene expression profiles, and tumorigenesis. Mutations in xenobiotic metabolic enzymes, as well as polymorphisms of tumor suppressor genes (e.g. p53) and/or genes involved in gene expression (e.g. X-ray repair cross-complementing proteins), are associated with lung cancer susceptibility in human populations from different ethnicities, gender, and age groups. Although various metabolic activation/inactivation pathways, AhR signaling, and genetic susceptibilities contribute to lung cancer, the precise points at which PAHs induce tumor initiation remain unknown. The goal of this review is to provide a current state-of-the-science of the mechanisms of human lung carcinogenesis mediated by PAHs, the experimental approaches used to study this complex class of compounds, and future directions for research of these compounds.

[Molecular epidemiology study in Xuanwei: the relationship among coal type, genotype and lung cancer risk]

背景与目的

已有的研究证明：宣威是我国农村肺癌死亡率最高的地区，肺癌危险与室内燃烧烟煤产生的多环芳烃（polycyclic aromatic hydrocarbons, PAHs）有关，肺癌发病具有明显的地域性差别和家族聚集性。本研究从分子流行病学角度探索宣威肺癌风险的危险因素及与发病机理有关的基因型和燃煤类型。

方法

运用两个基于人群的病例对照研究，开展问卷调查，同时采集口腔细胞和痰等生物样品，提取DNA。应用PCR法检测GST超家族、AKR超家族和OGG1等基因型。通过Logistic回归分析煤种、基因型与肺癌风险的关联。

结果

与燃用无烟煤或木柴的研究对象相比，家用来宾烟煤的肺癌风险比数比（odds ratio, OR）值高达24.8，其次为龙潭（OR=11.6）、宝山（OR=6.0）、龙场（OR=4.1）、羊场（OR=3.8）等；燃用同种烟煤的男女肺癌风险相似。对于GSTM1缺失、AKR1C3（Ex1-70C > G）、OGG1（Ex6-315C > G）基因型，肺癌风险明显增高，且具统计学意义[OR（95%CI）分别为2.3（1.3-4.2）、1.8（1.0-3.5）和1.9（1.1-3.3）]。与家用烟煤量小且具GSTM1阳性的研究对象相比，用量大且GSTM1缺失的研究对象肺癌风险更高，女性OR为4.9（1.3-18.2），男性OR为2.7（1.0-7.4）。但对于AKR1C3（Ex1-70C > G）和OGG1（Ex6-315C > G），仅观察到女性肺癌风险的明显增高，OR分别为12.9（2.2-107.8）和5.7（1.1-34.2）。

结论

宣威不同煤种的肺癌风险有很大差异，但暴露于相同煤种的男性与女性肺癌风险相似。GSTM1缺失基因型与肺癌风险增高有关联。AKR1C3与OGG1这2种基因型与肺癌风险有关联，且在烟煤使用量高的女性中肺癌风险更高。

Associations of CYP1A1, GSTM1 and GSTT1 polymorphisms with lung cancer susceptibility in a Northern Indian population

BACKGROUND

Susceptibility to lung cancer has been shown to be modulated by inheritance of polymorphic genes encoding cytochrome P450 1A1 (CYP1A1) and glutathione S transferases (GSTM1 and GSTT1), which are involved in the bioactivation and detoxification of environmental toxins. This might be a factor in the variation in lung cancer incidence with ethnicity.

MATERIALS AND METHODS

We conducted a case-control study of 218 northern Indian lung cancer patients along with 238 healthy controls, to assess any association between CYP1A1, GSTM1 and GSTT1 polymorphisms, either separately or in combination, with the likelihood of development of Lung cancer in our population.

RESULTS

We observed a significant difference in the GSTT1 null deletion frequency in this population when compared with other populations (OR=1.87, 95%CI: 1.25-2.80-0.73, P=0.002). However, GSTM1 null genotype was found associated with lung cancer in the non-smoking subgroup. (P=0.170).

CONCLUSIONS

Our study showed the GSTT1 null polymorphism to be associated with smoking-induced lung cancer and the GSTM1 null polymorphism to have a link with non-smoking related lung cancer.

Novel study on N-nitrosamines as risk factors of cardiovascular diseases

Millions of people are exposed daily to N-nitrosamines from different environmental sources. The present study aims at investigating the role of N-nitrosamines in the alteration of homocysteine, lipid profile, oxidative stress, paraoxonase activity, antioxidant enzymes, and free radicals which are important risk factors for CVD. In addition, biomarkers of cardiovascular diseases such as creatine kinase MB activity (CK-MB) and lactate dehydrogenase (LDH) as well as protein expression of both glutathione peroxidase and glutathione S-transferase π isozyme were assayed after treatment of rats with 0.2 mg/kg body weight of N-nitrosodibutylamine (NDBA), N-nitrosoethylbutylamine (NEBA), N-nitrosobutylpropylamine (NBPA), N-nitrosodiethylamine (NDEA), N-nitrosodimethylamine (NDMA), and N-nitrosodiphenylamine (NDPA) as a daily dose for two weeks. LDL levels, paraoxonase activity, reduced glutathione levels, and glutathione reductase activities were increased, whereas HDL levels decreased after treatment of rats with most of N-nitrosamines compared to control group. Moreover, levels of free radicals and catalase activity increased, whereas protein expression of both glutathione peroxidase and glutathione S-transferase decreased after treatment of rats with some N-nitrosamines. The data showed that most N-nitrosamines increased CK-MB and LDH activities. It is concluded that N-nitrosamines increased levels of free radicals, and decreased the activity of antioxidant enzymes which may consequently increase the incidence of CVDs.

Glutathione S-transferase M1 null genotype meta-analysis on gastric cancer risk

Background

Glutathione S-transferases (GSTs) have proved to be involved in the detoxifying several carcinogens and may play an important role in carcinogenesis of cancer. Previous studies on the association between Glutathione S-transferase M1 (GSTM1) polymorphism and gastric cancer (GC) risk reported inconclusive results. To get a precise result, we conducted this present meta-analysis through pooling all eligible studies.

Methods

A comprehensive databases of Pubmed, Embase, Web of Science, and the Chinese Biomedical Database (CBM) were searched for case–control studies investigating the association between GSTM1 null genotype and GC risk. Odds ratios (OR) and 95% confidence intervals (95% CI) were used to assess this possible association. A χ2-based Q-test was used to examine the heterogeneity assumption. Begg’s and Egger’s test were used to examine the potential publication bias. The leave-one-out sensitivity analysis was conducted to determine whether our assumptions or decisions have a major effect on the results of present work. Statistical analyses were performed with the software program STATA 12.0.

Results

A total of 47 eligible case–control studies were identified, including 6,678 cases and 12,912 controls. Our analyses suggested that GSTM1 null genotype was significantly associated with increased risk of GC (OR = 1.186, 95% CI = 1.057-1.329, P_{heterogenetiy} = 0.000, P = 0.004). Significant association was also found in Asians (OR = 1.269, 95% CI = 1.106-1.455, P_{heterogenetiy} = 0.002, P = 0.001). However, GSTM1 null genotype was not contributed to GC risk in Caucasians (OR = 1.115, 95% CI = 0.937-1.326, P_{heterogenetiy} = 0.000, P = 0.222). In the subgroup analysis stratified by sources of controls, significant association was detected in hospital-based studies (OR = 1.355, 95% CI = 1.179-1.557, P_{heterogenetiy} = 0.001, P = 0.000), while there was no significant association detected in population-based studies (OR = 1.017, 95% CI = 0.862-1.200, P_{heterogenetiy} = 0.000, P = 0.840).

Conclusion

This meta-analysis showed the evidence that GSTM1 null genotype contributed to the development of GC.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1644180505119533.

Association of GSTT1 and GSTM1 polymorphisms with blood pressure: A Bayesian modeling of continuous data

BACKGROUND

Systolic blood pressure (SBP) and diastolic blood pressure (DBP) are a multi-factorial traits and significantly heritable. Glutathione S-transferase (GST) enzyme is involved in detoxification of reactive oxygen species. The present study aimed at finding out the association between GSTM1 and GSTT1 polymorphisms and mean arterial pressure (MAP) in Iranian population. MAP, as the important indicator of blood pressure, is calculated by weighted averaging of SBP and DBP.

MATERIALS AND METHODS

we randomly selected 72 healthy individuals from Isfahan Cohort Study (ICS). Polymerase chain reaction (PCR) was done to detect polymorphism of the GSTM1 and GSTT1 genes. The Bayesian Structured Regression model was used, adjusted for sex, age, body mass index (BMI), and smoking status.

RESULTS

The results showed that both the GSTT1and GSTM1genotypes deletion had a significant effect on MAP increasing in our samples based on 95% Bayesian credible intervals.

CONCLUSION

This study demonstrated that GSTT1 and GSTM1 gene increase the arterial pressure; hence, it can predict the susceptibility to cardiovascular disease.

Cytochrome P450 1A1, 2E1 and GSTM1 gene polymorphisms and susceptibility to colorectal cancer in the Saudi population

BACKGROUND

The Saudi population has experienced a sharp increase in colorectal and gastric cancer incidences within the last few years. The relationship between gene polymorphisms of xenobiotic metabolizing enzymes and colorectal cancer (CRC) incidence has not previously investigated among the Saudi population. The aim of the present study was to investigate contributions of CYP1A1, CYP2E1, and GSTM1 gene polymorphisms.

MATERIALS AND METHODS

Blood samples were collected from CRC patients and healthy controls and genotypes were determined by polymerase chain reaction restriction fragment length polymorphism and sequencing.

RESULTS AND CONCLUSIONS

CYP2E1*6 was not significantly associated with CRC development (odd ratio=1.29; confidence interval 0.68-2.45). A remarkable and statistically significant association was observed among patients with CYP1Awt/*2A (odd ratio=3.65; 95% confidence interval 1.39-9.57). The GSTM1*0/*0 genotype was found in 2% of CRC patients under investigation. The levels of CYP1A1, CYP2E1 and GSTM1 mRNA gene expression were found to be 4, 4.2 and 4.8 fold, respectively, by quantitative real time PCR. The results of the present case-control study show that the studied Saudi population resembles Caucasians with respect to the considered polymorphisms. Investigation of genetic risk factors and susceptibility gene polymorphisms in our Saudi population should be helpful for better understanding of CRC etiology.

Oxaliplatin-induced neuropathy in colorectal cancer: many questions with few answers

Oxaliplatin is a chemotherapeutic agent effective against advanced colorectal cancer. Unlike with other platinum-based agents, the main side effect of oxaliplatin is polyneuropathy. Oxaliplatin-induced polyneuropathy (OIPN) has a unique profile, which can be divided into acute and chronic neurotoxicity. Early identification of the neurotoxicity and alterations in dose or schedule for the medication could prevent the development of chronic symptoms, which, once established, may take many months or years to resolve or even persist throughout life with a substantial effect on quality of life. There is no doubt that the use of pharmacogenomic methods to identify genetic bases of interindividual differences in drug response has led to what is called tailoring treatment. Yet there are some challenges regarding the application of these differences. Many efforts have been made to prevent or treat OIPN. Better understanding of the mechanisms underlying the acute and chronic forms of OIPN will be a key component of future advances in the prevention and treatment of OIPN. The aim of this review is to highlight the clinical presentation, assessment, and management of OIPN, as well as the underlying pathophysiologic and pharmacogenomic background.

Glutathione S transferase M1 andT1 genotypes and susceptibility to smoking related larynx cancer

Susceptibility to smoking related larynx cancer has been suggested to be associated with genetically determined differences in the ability to detoxify carcinogens present in tobacco smoke. The genetic polymorphisms of glutathione S-transferases, involved in the metabolic inactivation of, for example, tobacco derived carcinogens, have been recognized as potential risk modifiers in various environmentally induced malignancies, including larynx cancer. We employed PCR-based methods to determine the distribution of the GSTM 1 and G STT1 null genotypes in 171 larynx cancer patients and 180 controls to examine further their potential role in individual susceptibility to this neoplasm. The GSTM 1 null genotype was found in 49 1 % of the cases and 57 7 % of the controls and the GSTT1 null genotype in 17 5 % of the cases and 21 7 % of the controls, respectively. Larynx cancer risk associated with the lack of GST M 1 (OR = 0 7; 95 % CI: 0 5-1 1) or GSTT1 (OR = 0 8; 95 % CI: 0 5-1 3) was not significantly affected by age, smoking status, or cancer progression. Although this study thus suggests no role for the G STM 1 and GSTT1 gene polymorphisms in individual susceptibility to smoking-related larynx cancer, due to its relatively small sample size more data are required before any definite conclusions can be drawn.

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.

BPDE-like DNA adduct level in oral tissue may act as a risk biomarker of oral cancer

OBJECTIVE

Most reports have shown that PAH-related DNA adducts are positively correlated with the smoking status of oral cancer patients. However, these reports did not focus on a specific carcinogen in cigarette smoke. The purpose of this study was to elucidate the role of the BPDE (7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene)-DNA adduct in the development of oral cancer in Taiwanese patients.

DESIGN

We enrolled 158 oral cancer patients and 64 non-cancer controls to investigate whether there were differences in susceptibility to cigarette smoke exposure in the formation of DNA adducts between cancer patients and controls. Immunohistochemistry and ELISA (enzyme-linked immunosorbent assay) were used to evaluate BPDE-DNA adduct levels in this study.

RESULTS

Our data showed that the BPDE-DNA adduct levels were positively correlated with gender, smoking status, betel nut chewing and alcohol consumption. The difference in DNA adduct levels could be explained by genetic polymorphisms of glutathione S-transferase M1 (GSTM1), but not by cytochrome P-4501A1 (CYP1A1). Patients with high DNA adduct levels (≧34.03 adducts/10(8) nucleotides) had an approximately 9.936-fold risk of oral cancer compared with those with low DNA adduct levels (<34.03 adducts/10(8) nucleotides) (p<0.001).

CONCLUSIONS

We suggest that genetic background and carcinogen exposure may increase the risk of developing oral cancer.

Distinct SNP combinations confer susceptibility to urinary bladder cancer in smokers and non-smokers

Recently, genome-wide association studies have identified and validated genetic variations associated with urinary bladder cancer (UBC). However, it is still unknown whether the high-risk alleles of several SNPs interact with one another, leading to an even higher disease risk. Additionally, there is no information available on how the UBC risk due to these SNPs compare to the risk of cigarette smoking and to occupational exposure to urinary bladder carcinogens, and whether the same or different SNP combinations are relevant in smokers and non-smokers. To address these questions, we analyzed the genotypes of six SNPs, previously found to be associated with UBC, together with the GSTM1 deletion, in 1,595 UBC cases and 1,760 controls, stratified for smoking habits. We identified the strongest interactions of different orders and tested the stability of their effect by bootstrapping. We found that different SNP combinations were relevant in smokers and non-smokers. In smokers, polymorphisms involved in detoxification of cigarette smoke carcinogens were most relevant (GSTM1, rs11892031), in contrast to those in non-smokers with MYC and APOBEC3A near polymorphisms (rs9642880, rs1014971) being the most influential. Stable combinations of up to three high-risk alleles resulted in higher odds ratios (OR) than the individual SNPs, although the interaction effect was less than additive. The highest stable combination effects resulted in an OR of about 2.0, which is still lower than the ORs of cigarette smoking (here, current smokers' OR: 3.28) and comparable to occupational carcinogen exposure risks which, depending on the workplace, show mostly ORs up to 2.0.

Polymorphisms of glutathione S-transferases M1, T1, P1 and A1 genes in the Tunisian population: an intra and interethnic comparative approach

Genetic polymorphisms in glutathione S-transferases (GSTs) genes might influence the detoxification activities of the enzymes predisposing individuals to cancer risk. Owing to the presence of these genetic variants, inter-individual and ethnic differences in GSTs detoxification capacity have been observed in various populations. Therefore, the present study was performed to determine the prevalence GSTM1 0/0, GSTT1 0/0, GSTP1 Ile(105)Val, and GSTA1 A/B polymorphisms in 154 healthy individuals from South Tunisia, and to compare them with those observed in North and Centre Tunisian populations and other ethnic groups. GSTM1 and GSTT1 polymorphisms were analyzed by a Multiplex-PCR approach, whereas GSTP1 and GSTA1 polymorphisms were examined by PCR-RFLP. The frequencies of GSTM10/0 and GSTT1 0/0 genotypes were 53.9% and 27.9%, respectively. The genotype distribution of GSTP1 was 47.4% (Ile/Ile), 40.9% (Ile/Val), and 11.7% (Val/Val). For GSTA1, the genotype distribution was 24.7% (A/A), 53.9% (A/B), and 21.4% (B/B). The combined genotypes distribution of GSTM1, GSTT1, GSTP1 and GSTA1 polymorphisms showed that thirty one of the 36 possible genotypes were present in our population; eight of them have a frequency greater than 5%. To the best of our knowledge, this is the first report of GSTs polymorphisms in South Tunisian population. Our findings demonstrate the impact of ethnicity and reveal a characteristic pattern for Tunisian population. The molecular studies in these enzymes provide basis for further epidemiological investigations in the population where these functional polymorphisms alter therapeutic response and act as susceptibility markers for various clinical conditions.

Multiple analytical approaches reveal distinct gene-environment interactions in smokers and non smokers in lung cancer

Complex disease such as cancer results from interactions of multiple genetic and environmental factors. Studying these factors singularly cannot explain the underlying pathogenetic mechanism of the disease. Multi-analytical approach, including logistic regression (LR), classification and regression tree (CART) and multifactor dimensionality reduction (MDR), was applied in 188 lung cancer cases and 290 controls to explore high order interactions among xenobiotic metabolizing genes and environmental risk factors. Smoking was identified as the predominant risk factor by all three analytical approaches. Individually, CYP1A1*2A polymorphism was significantly associated with increased lung cancer risk (OR = 1.69;95%CI = 1.11–2.59,p = 0.01), whereas EPHX1 Tyr113His and SULT1A1 Arg213His conferred reduced risk (OR = 0.40;95%CI = 0.25–0.65,p<0.001 and OR = 0.51;95%CI = 0.33–0.78,p = 0.002 respectively). In smokers, EPHX1 Tyr113His and SULT1A1 Arg213His polymorphisms reduced the risk of lung cancer, whereas CYP1A1*2A, CYP1A1*2C and GSTP1 Ile105Val imparted increased risk in non-smokers only. While exploring non-linear interactions through CART analysis, smokers carrying the combination of EPHX1 113TC (Tyr/His), SULT1A1 213GG (Arg/Arg) or AA (His/His) and GSTM1 null genotypes showed the highest risk for lung cancer (OR = 3.73;95%CI = 1.33–10.55,p = 0.006), whereas combined effect of CYP1A1*2A 6235CC or TC, SULT1A1 213GG (Arg/Arg) and betel quid chewing showed maximum risk in non-smokers (OR = 2.93;95%CI = 1.15–7.51,p = 0.01). MDR analysis identified two distinct predictor models for the risk of lung cancer in smokers (tobacco chewing, EPHX1 Tyr113His, and SULT1A1 Arg213His) and non-smokers (CYP1A1*2A, GSTP1 Ile105Val and SULT1A1 Arg213His) with testing balance accuracy (TBA) of 0.6436 and 0.6677 respectively. Interaction entropy interpretations of MDR results showed non-additive interactions of tobacco chewing with SULT1A1 Arg213His and EPHX1 Tyr113His in smokers and SULT1A1 Arg213His with GSTP1 Ile105Val and CYP1A1*2C in nonsmokers. These results identified distinct gene-gene and gene environment interactions in smokers and non-smokers, which confirms the importance of multifactorial interaction in risk assessment of lung cancer.

Role of genetic changes in the progression of cardiovascular diseases

This review aims to investigate the role of genetic changes in the development of cardiovascular diseases [CVD]. Oxidation of Low density Lipoprotein (LDL) and mutations in LDL receptors gene are a trigger for numerous of atherogenic events. Also, endothelial nitric oxide synthase (eNOS) plays an important role in vasodilatation of blood vessels through synthesis of nitric oxide. Three single base pair changes, 786T/C, 922A/G, and 1468T/A, have been identified in the promoter region of the eNOS gene and are associated with coronary spasm. Moreover, two distinct variable nucleotide tandem repeats (VNTRs) in introns 4 and 13 have been detected. The presence of a minimum of 38 CA repeats in intron 13 has been associated with an independent 2.2-fold increase in the risk of coronary artery disease [CAD]. Plasma glutathione peroxidase (GPx-3) maintains the vascular bioavailability of nitric oxide (NO), through depletion of reactive oxygen species. Mutation(s) or polymorphism(s) in the plasma GPx-3 gene promoter may predispose to a thrombotic disorder, and constitute a genetic risk factor for thrombotic cerebrovascular disease. Hyperhomocysteinemia is another independent risk factor for atherosclerosis and arterial thrombosis. Severe hyperhomocysteinemia could be caused by cystathionine-β-synthase enzyme deficiency but it could be due to homozygosity of a common 677C/T point mutation in the coding region of the methylenetetrahydrofolate reductase (MTHFR) gene as a 3-fold increase in risk of CAD is associated with the MTHFR 677TT genotype. A second common variant in MTHFR 1298A/C is associated with decreased enzyme activity in vitro and in vivo, especially when occurring simultaneously with the 677 C/T polymorphism. Elevated fibrinogen, an essential component of the coagulation system, has been most consistently associated with arterial thrombotic disorders. Several polymorphisms (148C/T, 455G/A, and -854G/A) have been identified in the genes encoding the 3 pairs of fibrinogen polypeptide chains. The -455G/A, and -854G/A substitutions are the most physiologically relevant mutations. In addition the -455A allele has been associated with the progression of atheroma, and also with a 2.5-fold increase in risk of multiple lacunar infarcts in a cohort of elderly patients with stroke. It is concluded that genetic changes in the previously mentioned genes could play a significant role in the initiation and progression of CVD. This review provides useful information for both physicians and medical students whom are interested in human genetics which is related to cardiovascular diseases.

Association of GSTM1 and GSTT1 polymorphisms with DNA damage in coal-tar workers

DNA damage was evaluated by alkaline comet assay in peripheral blood lymphocytes of 115 coal-tar workers occupationally exposed to polycyclic aromatic hydrocarbons (PAHs) and 105 control subjects. The effect of polymorphisms of glutathione S-transferase (GST) genotypes on the DNA damage was assessed. The mean tail moment (TM) value in the coal-tar workers was significantly higher as compared to the control subjects (12.06 ± 0.55 versus 0.44 ± 0.31; P<0.05). No significant association (P>0.05) between the GSTT1 and GSTM1 genotypes and the TM values was found, however highest mean rank TM value was reported in GSTM1 null and GSTT1 null genotypes in both control and exposed subjects. Our results suggest that there is increased DNA damage in coal-tar workers due to PAHs exposure. Polymorphisms in GSTM1 and GSTT1 genes do not show significant effect (P>0.05) on DNA damage.

Association of genetic polymorphism of GSTT1, GSTM1 and GSTM3 in COPD patients in a north Indian population

Environmental exposures and genetic susceptibility can contribute to lung function decline in chronic obstructive pulmonary disease (COPD). Cigarette smoking is the main etiological factor for decline in lung function in COPD. However, only 10-20% chronic smokers develop symptomatic COPD. Genetic susceptibility to COPD might depend upon the variation of enzyme activities that detoxify cigarette smoke components. We performed a case control study to assess the association of Glutathione- S-transferase T1(GSTT1),Glutathione- S-transferase M1 (GSTM1), and Glutathione-S-transferase M3(GSTM3) common polymorphisms with the susceptibility to COPD patient in a north India population. In the present study, the genotypes of 412 subjects, (204 COPD patients and 208 healthy controls) were analyzed. Statistical analysis revealed that the frequency of homozygous GSTM1 null genotype was found to be significant higher in COPD patients as compared with healthy controls (OR, 2.58; 95% CI, 1.73-3.84; P = 0.001), but there were no significant differences in the distribution of homozygous null GSTT1 and 3-bp deletion polymorphism (rs1799735) in intron 6 variant allele in GSTM3 between COPD patients and healthy controls. Our study results suggest that GSTM1 null polymorphism is associated with genetic susceptibility to COPD. Moreover, we also found association between this polymorphism with pulmonary function test in smokers as well as nonsmokers.

Polymorphisms of CYP1A1, GSTM1 and GSTT1 Loci as the Genetic Predispositions of Oral Cancers and Other Oral Pathologies: Tobacco and Alcohol as Risk Modifiers

Polycyclic aromatic hydrocarbons of tobacco require activation by phase I enzymes, such as cytochrome-P4501A1 (CYP1A1) to become an ultimate carcinogen, which are subjected to detoxification by phase II enzymes, especially glutathione S-transferases (GSTs). A study was designed to find whether genetic predisposition are risk modifiers of oral pathologies. The study included 102 cases with Oral Cancers (OCs), 68 cases with nonmalignant pathologies, 100 cases as control group. GSTM1 null genotype was associated with increased risk of OCs but not with benign pathologies. Deleted GSTT1 was associated with all pathologies. Both m1m2 and m2m2 polymorphisms of CYP1A1 were associated with oral pathologies.

CYP1A1 gene polymorphisms as a risk factor for pterygium

PURPOSE

Both cytochrome P4501A1 (CYP1A1) and glutathione S-transferase M1 (GSTM1) have been demonstrated to be involved in the metabolism of polycyclic aromatic hydrocarbons (PAHs). BaP 7,8-diol 9,10-epoxide (BPDE), an ultimate metabolite of benzo(a)pyrene (BaP), attacks deoxyguanosine to form a BPDE-N2-dG adduct resulting in p53 gene mutations. Our previous report indicated that BPDE-like DNA adduct levels in pterygium were associated with CYP1A1 gene polymorphisms. Therefore, we hypothesize that the genetic polymorphisms of CYP1A1 and GSTM1 increase the risk for pterygium.

METHODS

Two hundred-five pterygial specimens and 206 normal controls were collected in this study. For the analysis of CYP1A1 and GSTM1 gene polymorphisms, DNA samples were extracted from blood cells and then subjected to restriction fragment length polymorphism and polymerase chain reaction for the determination of mutation and genotype of CYP1A1 and GSTM1.

RESULTS

There was a significant difference between the case and control groups in the CYP1A1 genotype (p=0.0161) but not in GSTM1 (p=1.000). The odds ratio of the CYP1A1 m1/m2 polymorphism was 1.327 (95% CI=0.906-2.079, p=0.135) and the m2/m2 polymorphism was 1.647 (95% CI=1.154-2.350, p=0.006), compared to the m1/m1 wild-type genotype. The GSTM1 polymorphisms did not have an increased odds ratio compared with the wild type.

CONCLUSIONS

In conclusion, a CYP1A1 polymorphism is correlated with pterygium and might become a marker for the prediction of pterygium susceptibility.

Glutathione S-transferase T1 gene deletion polymorphism and lung cancer risk in Chinese population: a meta-analysis

Genetic variations in metabolic genes are considered to modulate metabolic process of carcinogens and are suggested to be related to cancer risk. However, epidemiological results are not always consistent. In this meta-analysis, we evaluated reported studies of association between polymorphism of glutathione S-transferase T1 gene (GSTT1) and the risk of lung cancer in Chinese population. We found an increased lung cancer risk among subjects carrying GSTT1 null genotype [odds ratio (OR)=1.36, 95 percent confidence interval (95% CI): 1.09-1.69], using 1625 cases and 2188 controls from 11 studies. We also observed an increased risk of lung cancer among null genotype carriers in squamous cell carcinoma and adenocarcinoma, and on the basis of population control in stratified analyses. The meta-analysis suggests that GSTT1 deletion polymorphisms may have an effect on the susceptibility of lung cancer in Chinese population, and a study with the larger sample size is needed to further evaluate gene-gene and gene-environment interaction on GSTT1 deletion polymorphisms and lung cancer risk in Chinese population.

An association between BPDE-like DNA adduct levels and CYP1A1 and GSTM1 polymorphisma in pterygium

PURPOSE

Benzo[a]pyrene 7,8-diol 9,10-epoxide (BPDE), an ultimate metabolite of benzo[a]pyrene, attacks deoxyguanosine to form a BPDE-N2-dG adduct resulting in p53 mutations. Both cytochrome P4501A1 (CYP1A1) and glutathione S-transferase M1 (GSTM1) have been demonstrated to be involved in the metabolism of polycyclic aromatic hydrocarbons. The relationship between BPDE-like DNA adduct levels and CYP1A1 and GSTM1 gene polymorphisms in pterygium is not clear. Therefore, BPDE-like DNA adducts and CYP1A1 and GSTM1 polymorphisms were detected in this study to provide more molecular evidence to understand the cause of BPDE-like DNA adduct formation in pterygium.

METHODS

In this study, immunohistochemical staining using a polyclonal antibody on BPDE-like DNA adducts was performed on 103 pterygial specimens. For the analysis of CYP1A1 and GSTM1 polymorphisms, DNA samples were extracted from epithelial cells and then subjected to restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR) for the determination of mutation and genotype of CYP1A1 and GSTM1.

RESULTS

BPDE-like DNA adducts were detected in 33.0% (34/103) of the pterygium samples. The differences in DNA adduct levels were associated with the genetic polymorphisms of CYP1A1 but not GSTM1. Additionally, the risk of BPDE-like DNA adduct formation for patients with CYP1A1 m1/m2 (C/T) andm2/m2 (T/T) was 9.675 fold higher than that of patients with CYP1A1 m1/m1 (C/C) types (p=0.001, 95% Confidence Interval 2.451-38.185).

CONCLUSIONS

Our data provide evidence that the BPDE-like DNA adduct formation in pterygium samples was associated with CYP1A1 polymorphisms.

Genetic polymorphism of glutathione S-transferase M1 and T1 in Delhi population of Northern India

Glutathione S-transferases (GSTs), protect cells from reactive chemical intermediates and oxidative stress. Among different classes of GSTs, GSTM1 (Mu) and GSTT1 (theta) are found to be genetically deleted. Present study was intended to genotype homozygous null distribution of GSTM1 and GSTT1 in healthy individuals of Delhi, located in Northern India. Out of 309 healthy individuals included in this study, we have found genetic deletion in 21% and 27.4%, GSTM1 and GSTT1 genes, respectively. A small proportion (0.7%) population showed deletion of both the genes. The prevalence of the GSTM1(*)0/0 and GSTT1(*)0/0 genotypes varied within India compared to communities in Chinese, Japanese, Korean and Caucasian.

Meta- and pooled analysis of GSTP1 polymorphism and lung cancer: a HuGE-GSEC review

Lung cancer is the most common cancer worldwide. Polymorphisms in genes associated with carcinogen metabolism may modulate risk of disease. Glutathione S-transferase pi (GSTP1) detoxifies polycyclic aromatic hydrocarbons found in cigarette smoke and is the most highly expressed glutathione S-transferase in lung tissue. A polymorphism in the GSTP1 gene, an A-to-G transition in exon 5 (Ile105Val, 313A --> 313G), results in lower activity among individuals who carry the valine allele. The authors present a meta- and a pooled analysis of case-control studies that examined the association between this polymorphism in GSTP1 and lung cancer risk (27 studies, 8,322 cases and 8,844 controls and 15 studies, 4,282 cases and 5,032 controls, respectively). Overall, the meta-analysis found no significant association between lung cancer risk and the GSTP1 exon 5 polymorphism. In the pooled analysis, there was an overall association (odds ratio = 1.11, 95% confidence interval: 1.03, 1.21) between lung cancer and carriage of the GSTP1 Val/Val or Ile/Val genotype compared with those carrying the Ile/Ile genotype. Increased risk varied by histologic type in Asians. There appears to be evidence for interaction between amount of smoking, the GSTP1 exon 5 polymorphism, and risk of lung cancer in whites.

Glutathione S-transferase and microsomal epoxide hydrolase gene polymorphisms and risk of chronic obstructive pulmonary disease in Slovak population

AIM

To determine the risk of chronic obstructive pulmonary disease (COPD) associated with polymorphisms in the glutathione S-transferase (GST) M1, GST T1, and microsomal epoxide hydrolase (EPHX1) genes in a cohort of Slovak population.

METHODS

Two hundred and seventeen patients with the diagnosis of COPD and 160 control subjects were enrolled in the study. Blood samples were collected from all subjects and the DNA from peripheral blood lymphocytes was used for subsequent genotyping assays, using polymerase chain reaction and restriction fragment-length polymorphism methods.

RESULTS

In an unadjusted model, an increased risk for COPD was observed in subjects with EPHX1 His113-His113 genotype (odds ratio [OR], 2.32; 95% confidence interval [CI], 1.20-4.69; P=0.008), compared with the carriers of the Tyr113 allele. However, after the adjustments for age, sex, and smoking status, the risk was not significant (adjusted OR, 1.79; 95% CI, 0.91-3.53; P=0.093). In a combined analysis of gene polymorphisms, the genotype combination EPHX1 His113-His113/GSTM1 null significantly increased the risk of COPD in both, unadjusted (OR, 5.08; 95% CI, 1.70-20.43; P=0.001) and adjusted model (OR, 4.87; 95% CI, 1.57-15.13; P=0.006).

CONCLUSION

Although none of the tested gene polymorphisms was significantly related to an increased risk of COPD alone, our results suggest that the homozygous exon 3 mutant variant of EPHX1 gene in the combination with GSTM1 null genotype is a significant predictor of increased susceptibility to COPD in the Slovak population. The findings of the present study emphasize the importance of detoxifying and antioxidant pathways in the pathogenesis of COPD.

Assessment of interactions between PAH exposure and genetic polymorphisms on PAH-DNA adducts in African American, Dominican, and Caucasian mothers and newborns

Polycyclic aromatic hydrocarbons (PAH) are widespread pollutants commonly found in air, food, and drinking water. Benzo[a]pyrene is a well-studied representative PAH found in air from fossil fuel combustion and a transplacental carcinogen experimentally. PAHs bind covalently to DNA to form DNA adducts, an indicator of DNA damage, and an informative biomarker of potential cancer risk. Associations between PAH-DNA adduct levels and both cancer risk and developmental deficits have been seen in previous experimental and epidemiologic studies. Several genes have been shown to play an important role in the metabolic activation or detoxification of PAHs, including the cytochrome P450 genes CYP1A1 and CYP1B1 and the glutathione S-transferase (GST) genes GSTM1, and GSTT2. Genetic variation in these genes could influence susceptibility to adverse effects of PAHs in polluted air. Here, we have explored interactions between prenatal PAH exposure and 17 polymorphisms in these genes (rs2198843, rs1456432, rs4646903, rs4646421, rs2606345, rs7495708, rs2472299, rs162549, rs1056837, rs1056836, rs162560, rs10012, rs2617266, rs2719, rs1622002, rs140194, and gene deletion GSTM1-02) and haplotypes on PAH-DNA adducts in cord blood of 547 newborns and in maternal blood of 806 mothers from three different self-described ethnic groups: African Americans, Dominicans, and Caucasians. PAHs were measured by personal air monitoring of mothers during pregnancy. Significant interactions (p < 0.05) were observed between certain genetic polymorphisms and CYP1A1 haplotype and PAHs in mothers and their newborns in the three ethnic groups. However, with our limited sample size, the current findings are suggestive only, warranting further study.

A genome-wide association study identifies protein quantitative trait loci (pQTLs)

There is considerable evidence that human genetic variation influences gene expression. Genome-wide studies have revealed that mRNA levels are associated with genetic variation in or close to the gene coding for those mRNA transcripts – cis effects, and elsewhere in the genome – trans effects. The role of genetic variation in determining protein levels has not been systematically assessed. Using a genome-wide association approach we show that common genetic variation influences levels of clinically relevant proteins in human serum and plasma. We evaluated the role of 496,032 polymorphisms on levels of 42 proteins measured in 1200 fasting individuals from the population based InCHIANTI study. Proteins included insulin, several interleukins, adipokines, chemokines, and liver function markers that are implicated in many common diseases including metabolic, inflammatory, and infectious conditions. We identified eight Cis effects, including variants in or near the IL6R (p = 1.8×10⁻⁵⁷), CCL4L1 (p = 3.9×10⁻²¹), IL18 (p = 6.8×10⁻¹³), LPA (p = 4.4×10⁻¹⁰), GGT1 (p = 1.5×10⁻⁷), SHBG (p = 3.1×10⁻⁷), CRP (p = 6.4×10⁻⁶) and IL1RN (p = 7.3×10⁻⁶) genes, all associated with their respective protein products with effect sizes ranging from 0.19 to 0.69 standard deviations per allele. Mechanisms implicated include altered rates of cleavage of bound to unbound soluble receptor (IL6R), altered secretion rates of different sized proteins (LPA), variation in gene copy number (CCL4L1) and altered transcription (GGT1). We identified one novel trans effect that was an association between ABO blood group and tumour necrosis factor alpha (TNF-alpha) levels (p = 6.8×10⁻⁴⁰), but this finding was not present when TNF-alpha was measured using a different assay , or in a second study, suggesting an assay-specific association. Our results show that protein levels share some of the features of the genetics of gene expression. These include the presence of strong genetic effects in cis locations. The identification of protein quantitative trait loci (pQTLs) may be a powerful complementary method of improving our understanding of disease pathways.

One of the central dogmas of molecular genetics is that DNA is transcribed to RNA which is translated to protein and alterations to proteins can influence human diseases. Genome-wide association studies have recently revealed many new DNA variants that influence human diseases. To complement these efforts, several genome-wide studies have established that DNA variation influences mRNA expression levels. Loci influencing mRNA levels have been termed “eQTLs”. In this study we have performed the first genome-wide association study of the third piece in this jigsaw – the role of DNA variation in relation to protein levels, or “pQTLs”. We analysed 42 proteins measured in blood fractions from the InCHIANTI study. We identified eight cis effects including common variants in or near the IL6R, CCL4, IL18, LPA, GGT1, SHBG, CRP and IL1RN genes, all associated with blood levels of their respective protein products. Mechanisms implicated included altered transcription (GGT1) but also rates of cleavage of bound to unbound soluble receptor (IL6R), altered secretion rates of different sized proteins (LPA) and variation in gene copy number (CCL4). Blood levels of many of these proteins are correlated with human diseases and the identification of “pQTLs” may in turn help our understanding of disease.

Association of periodontitis with GSTM1/GSTT1-null variants—A pilot study

OBJECTIVES

To analyze a possible association between glutathione-S-transferase T1 (GSTM1) and/or glutathione-S-transferase M1 (GSTM1) polymorphisms and chronic or aggressive forms of periodontitis in a Caucasian ethnic group.

DESIGN AND METHODS

Sixty-nine chronic, 14 aggressive periodontitis and 61 controls, deeply analyzed from a clinical point of view, were studied for their GSTM1 and GSTT1 polymorphisms by allelic specific PCR techniques. As a second control group, 64 blood donors were also included.

RESULTS

A significant association was found between GSTM1-null genotype and both chronic and aggressive periodontitis. The aggressive forms were associated with the double null GSTM1 and GSTT1 combination. These results were independent of the patients' age, gender, hygienic habits and smoke (evaluated as tobacco smoking yes/no, cigarettes/day and pack years) as confirmed by multivariate logistic regression analysis.

CONCLUSIONS

The GSTM1-null variant is statistically associated with the two forms of periodontitis, while the aggressive one also presents a second null variant: GSTT1.