Diversity of glutathione s-transferase omega 1 (a140d) and 2 (n142d) gene polymorphisms in worldwide populations

The role of glutathione S-transferase omega gene polymorphisms in childhood acute lymphoblastic leukemia: a case-control study

Background

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Glutathione-S-methyl transferase (GSTs) enzymes’ family is known to catalyze carcinogens detoxification. Overexpression of (GSTO) omega class was reported in cancer occurrence. The purpose of the study was to investigate the association of GSTO1*A140D (rs4925) and GSTO2*N142D (rs156697) polymorphisms with the susceptibility to childhood ALL and to evaluate their prognostic impact. Genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism technique in 96 Egyptian pediatric ALL patients and 99 controls.

Results

No statistically significant different GSTO1*A140D genotype and allele distribution was observed among ALL cases and controls; however, a statistically significant different GSTO1*A140D genotype distribution was found between de novo ALL cases and controls [CC (37% vs. 56.6%), CA (47.8% vs. 40.4%), and AA (15.2% vs. 3.0%), respectively] (0.008). GSTO1*A140D variant genotypes’ frequency was significantly higher in de novo cases than in controls (63% vs. 43.4%) (0.028). The minor allele frequency (MAF) of GSTO1*A140D-A was significantly higher in de novo cases compared to controls (0.39 vs. 0.23) (0.005). Genotyping of GSTO2*N142D revealed a statistically significant difference of genotype distribution between ALL patients and controls [AA (26% vs. 36.3%), AG (62.5% vs. 61.6%), and GG (11.4% vs. 2.0%), respectively] (0.017) and between de novo ALL cases and controls [AA (37% vs. 36.3%), AG (45.7% vs. 61.6%), and GG (17.3% vs. 2.0%), respectively] (0.002). The MAF of GSTO2*N142D-G was significantly higher in ALL patients than in controls (0.42 vs. 0.32) (0.046). The high-risk ALL group had a higher frequency of GSTO1*A140D and GSTO2*N142D variant genotypes compared to corresponding wild genotypes and a higher frequency of combined polymorphisms compared to single polymorphisms and wild genotypes but with no statistically significant difference.

Conclusion

A statistically significant difference of GSTO1*A140D and GSTO2*N142D genotype distribution was detected between de novo ALL cases and controls. Compared to the control group, the MAF of GSTO1*A140D-A was overexpressed in de novo ALL cases and that of GSTO2*N142D-G was significantly higher in ALL patients. These findings suggest that the studied polymorphisms might play a significant role in the susceptibility to de novo childhood ALL in Egypt; however, GSTO1*A140D and/or GSTO2*N142D polymorphisms have no impact on ALL prognosis.

Human variability in glutathione-S-transferase activities, tissue distribution and major polymorphic variants: Meta-analysis and implication for chemical risk assessment

The input into the QIVIVE and Physiologically-Based kinetic and dynamic models of drug metabolising enzymes performance and their inter-individual differences significantly improve the modelling performance, supporting the development and integration of alternative approaches to animal testing. Bayesian meta-analyses allow generating and integrating statistical distributions with human in vitro metabolism data for quantitative in vitro-in vivo extrapolation. Such data are lacking on glutathione-S-transferases (GSTs). This paper reports for the first time results on the human variability of GST activities in healthy individuals, their tissue localisation and the frequencies of their major polymorphic variants by means of extensive literature search, data collection, data base creation and meta-analysis. A limited number of papers focussed on in vivo GST inter-individual differences in humans. Ex-vivo total GST activity without discriminating amongst isozymes is generally reported, resulting in a high inter-individual variability. The highest levels of cytosolic GSTs in humans are measured in the kidney, liver, adrenal glands and blood. The frequencies of GST polymorphisms for cytosolic isozymes in populations of different geographical ancestry were also presented. Bayesian meta-analyses to derive GST-related uncertainty factors provided uncertain estimates, due to the limited database. Considering the relevance of GST activities and their pivotal role in cellular adaptive response mechanisms to chemical stressors, further studies are needed to identify GST probe substrates for specific isozymes and quantify inter-individual differences.

Comparison of arsenic methylation capacity and polymorphisms of arsenic methylation genes between bladder cancer and upper tract urothelial carcinoma

Arsenic exposure is an environmental risk factor for urothelial carcinoma (UC). The natural history of upper tract urothelial carcinoma (UTUC) differs from that of bladder cancer (BC). However, the risk factors of BC and UTUC are not exactly the same and should be discussed separately. The aims of this study were to evaluate 1) the association between arsenic methylation capacity and UTUC and/or BC, separately, and 2) the association between polymorphisms of the arsenic metabolism-related genes AS3MT, GSTOs, and PNP against BC and/or UTUC, separately. We conducted a hospital-based study and collected 216 BC and 212 UTUC cases, and 813 healthy controls, from September 2007 to October 2011. Urinary arsenic profiles were measured using high-performance liquid chromatography-hydride generator-atomic absorption spectrometry. The polymorphisms of AS3MT, GSTO, and PNP were identified using the Sequenom MassARRAY platform with iPLEX Gold chemistry. We found that inefficient arsenic methylation capacity was associated with BC in a significant dose-response relationship, but only found that high urinary total arsenic concentration was related to the risk of UTUC, also in a significant dose-response manner. Those with a total urinary arsenic level of > 30.28 μg/L compared to ≤ 9.78 μg/L, had a odds ratio (OR), and 95% confidence interval (CI) of UTUC, of 4.80 (2.22-10.39). The polymorphisms of AS3MT rs11191438, AS3MT rs10748835, and AS3MT rs1046778 were related to the risk of BC and UTUC, while the polymorphisms of AS3MT rs3740393, AS3MT rs11191453, and AS3MT rs11191454 were associated with arsenic methylation capacity. The AS3MT gene polymorphisms and arsenic methylation capacity appear to independently affect the risk of BC and UTUC.

Association between arsenic metabolism gene polymorphisms and arsenic-induced skin lesions in individuals exposed to high-dose inorganic arsenic in northwest China

Individuals in a given environment contaminated with arsenic have different susceptibilities to disease, which may be related to arsenic metabolism, age, gender, genetics and other factors. This study recruited 850 subjects, including 331 cases and 519 controls, from populations exposed to high levels of arsenic in drinking water in northwest China. Genotypes were determined using a custom-by-design 48-Plex SNPscan^TM kit. The results indicated that subjects who carried at least one C allele for GSTO1 rs11191979 polymorphism, at least one A allele for GSTO1 rs2164624, at least one A allele for GSTO1 rs4925, the AG genotype for GSTO2 rs156697, the AG genotype or at least one G allele for GSTO2 rs2297235 or the GG genotype or at least one G allele for PNP rs3790064 had an increased risk of arsenic-related skin lesions. In addition, the haplotype CT between rs4925 and rs11191979 appeared to confer a high risk of arsenic-included skin lesions (OR = 1.377, 95% CI = 1.03–1.84), as did the haplotype GCG among rs156697, rs157077 and rs2297235 (OR = 2.197, 95% CI = 1.08–4.44). The results showed that the variants of GSTO1, GSTO2 and PNP render the susceptible toward developing arsenic-induced skin lesions in individuals exposed to high-dose inorganic arsenic in northwest China.

Interactive Influence of N6AMT1 and As3MT Genetic Variations on Arsenic Metabolism in the Population of Inner Mongolia, China

Chronic arsenic exposure via drinking water has become a worldwide public health concern. In humans, inorganic arsenic (iAs) is metabolized to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) mainly mediated by arsenic (+3 oxidation state) methyltransferase (As3MT). We reported recently that N-6 adenine-specific DNA methyltransferase 1 (N6AMT1) was involved in arsenic metabolism, and examined its interactive effect with As3MT on arsenic metabolism in vitro To further evaluate the interactive effect of N6AMT1 and As3MT on arsenic biomethylation in humans, we conducted a human population-based study including 289 subjects living in rural villages in Inner Mongolia, China, and assessed their urinary arsenic metabolites profiles in relation to genetic polymorphisms and haplotypes of N6AMT1 and As3MT Five N6AMT1 single nucleotide polymorphisms (SNPs; rs1003671, rs7282257, rs2065266, rs2738966, rs2248501) and the N6AMT1 haplotype 2_GGCCAT were significantly associated with the percentage of iAs (% iAs) in urine (e.g., for rs7282257, mean was 9.62% for TT, 6.73% for AA). Rs1003671 was also in a significant relationship with urinary MMA and DMA (the mean of %MMA was 24.95% for GA, 31.69% for GG; the mean of % DMA was 69.21% for GA, 59.82% for GG). The combined effect of N6AMT1 haplotype 2_GGCCAT and As3MT haplotype 2_GCAC showed consistence with the additive significance of each haplotype on % iAs: the mean was 5.47% and 9.36% for carriers with both and null haplotypes, respectively. Overall, we showed that N6AMT1 genetic polymorphisms were associated with arsenic biomethylation in the Chinese population, and its interaction with As3MT was observed in specific haplotype combinations.

Association of glutathione S-transferase omega gene polymorphisms with progression of head and neck cancer

This study investigated the influence of glutathione S-transferase omega 1 (GSTO1) and GSTO2 gene polymorphisms on susceptibility and aggressiveness of head and neck squamous cell carcinoma (HNSCC). A case-control study consisting of 300 HNSCC cases and 299 age and sex- matched normal control was performed. Genotyping of GSTO1*A140D and GSTO2*N142D polymorphisms was determined using the polymerase chain reaction-restriction fragment length polymorphism method. Our results revealed that the frequencies of GSTO1 and GSTO2 genotypes were not significantly different between HNSCC cases and controls. No significant differences were found in smoking or drinking status between cases and controls. However, HNSCC individuals with the GSTO1*D140 varient were significantly associated with nodal metastasis (OR = 0.53, 95 %CI = 0.31-0.91, P = 0.020) and advanced pathological stage (OR = 0.33,95 %CI = 0.15-0.70, P = 0.032), while no significant association was observed between GSTO2 genotype and clinicopathological features. Therefore, our findings suggest that the GSTO1*D140 variant genotype in individuals might play a protective role against the aggressiveness of HNSCC.

The MMACHC proteome: hallmarks of functional cobalamin deficiency in humans

Cobalamin (Cbl, B(12)) is an essential micronutrient required to fulfill the enzymatic reactions of cytosolic methylcobalamin-dependent methionine synthase and mitochondrial adenosylcobalamin-dependent methylmalonyl-CoA mutase. Mutations in the MMACHC gene (cblC complementation group) disrupt processing of the upper-axial ligand of newly internalized cobalamins, leading to functional deficiency of the vitamin. Patients with cblC disease present with both hyperhomocysteinemia and methylmalonic acidemia, cognitive dysfunction, and megaloblastic anemia. In the present study we show that cultured skin fibroblasts from cblC patients export increased levels of both homocysteine and methylmalonic acid compared to control skin fibroblasts, and that they also have decreased levels of total intracellular folates. This is consistent with the clinical phenotype of functional cobalamin deficiency in vivo. The protein changes that accompany human functional Cbl deficiency are unknown. The proteome of control and cblC fibroblasts was quantitatively examined by two dimensional difference in-gel electrophoresis (2D-DIGE) and liquid chromatography-electrospray ionization-mass spectrometry (LC/ESI/MS). Major changes were observed in the expression levels of proteins involved in cytoskeleton organization and assembly, the neurological system and cell signaling. Pathway analysis of the differentially expressed proteins demonstrated strong associations with neurological disorders, muscular and skeletal disorders, and cardiovascular diseases in the cblC mutant cell lines. Supplementation of the cell cultures with hydroxocobalamin did not restore the cblC proteome to the patterns of expression observed in control cells. These results concur with the observed phenotype of patients with the cblC disorder and their sometimes poor response to treatment with hydroxocobalamin. Our findings could be valuable for designing alternative therapies to alleviate the clinical manifestation of the cblC disorder, as some of the protein changes detected in our study are common hallmarks of known pathologies such as Alzheimer's and Parkinson's diseases as well as muscular dystrophies.

A unique genome-wide association analysis in extended Utah high-risk pedigrees identifies a novel melanoma risk variant on chromosome arm 10q

Only two genome-wide association (GWA) screens have been published for melanoma (Nat Genet 47:920-925, 2009; Nat Genet 40:838-840, 2008). Using a unique approach, we performed a genome-wide association study in 156 related melanoma cases from 34 high-risk Utah pedigrees. Genome-wide association analysis was performed on nearly 500,000 markers; we compared cases to 2,150 genotypically matched samples from Illumina's iControls database. We performed genome-wide association with EMMAX software, which is designed to account for population structure, including relatedness between cases. Three SNPs exceeded a genome-wide significance threshold of p < 5 × 10(-8) on chromosome arm 10q25.1 (rs17119434, rs17119461, and rs17119490), where the most extreme p value was 7.21 × 10(-12). This study represents a new and unique approach to predisposition gene identification; and it is the first genome-wide association study performed in related cases in high-risk pedigrees. Our approach illustrates an example of using high-risk pedigrees for the identification of new melanoma predisposition variants.

Association between N142D genetic polymorphism of GSTO2 and susceptibility to colorectal cancer

Expression pattern analysis has been revealed that glutathione S-transferase omega 2 (GSTO2, a member of class omega) is ubiquitously expressed. Over expression of GSTO2 induced apoptosis. The gene encoding GSTO2 was localized to human chromosome 10q24.3, a region that may harbor gene(s) involved in the developing of colorectal cancer. To investigate the association between GSTO2 N142D genetic polymorphism and susceptibility to colorectal cancer the present study was done. We studied 63 (26 females, 37 males) colorectal cancer patients and 126 (52 females, 74 males) healthy individuals. The control subjects were frequency matched for age and gender with the colorectal cancer group. The genotypes were performed using RFLP-PCR method. The ND and DD genotypes were not associated with risk of colorectal cancer, in comparison with the NN genotype. Family history for cancer in the first degree of relatives significantly differed between cases and controls (P = 0.012). The profiles of GSTO2 genotypes and family history in control and cancerous groups were compared to each other. Subjects with NN genotype and positive family history significantly were at high risk to develop colorectal cancer in comparison with subjects with DD or ND genotypes and negative family history (P = 0.003). Present findings indicating that GSTO2 NN genotype increase the risk of colorectal cancer in persons with positive family history for cancer in the first degree relatives.

Glutathione S-transferase ω class (GSTO) polymorphisms in a sample from Rome (Central Italy)

Glutathione S-transferases are a superfamily of enzymes that are involved in biotransformation of drugs, xenobiotics and play a fundamental role in the protection of cells from oxidative stress. In humans, the recently described GST Omega class contains two expressed genes GSTO1 and GSTO2, located on chromosome 10 (10q24.3). Four polymorphisms in GSTO genes have been identified in ethnic groups: GSTO1*A140D (rs4925), GSTO1*E155del (rs56204475), GSTO1*E208K (rs11509438) and GSTO2*N142D (rs156697). This study provides the allele frequencies of GSTO polymorphism in a sample consisting of 116 apparently healthy individuals of both sexes from Rome (Central Italy). Detection of GSTO1*A140D and GSTO2*N142D alleles was performed by PCR-RFLP analysis, while GSTO1*E155del and GSTO1*E208K alleles were detected using the Confronting Two-Pair Primers analysis (PCR-CTPP) and allele specific PCR, respectively. The GSTO allele frequencies found in the Italian sample were included in the variability range observed in European populations. Comparison between the data presented in this study and data in previous studies showed different patterns among European, Asian and African populations.

Glutathione S-transferase gene polymorphisms and air pollution as interactive risk factors for asthma in a multicentre Italian field study: A preliminary study

BACKGROUND

Asthma is one of the most common chronic diseases. Several studies have indicated that oxidative stress impairs pulmonary function. Glutathione S-transferases (GSTs) are believed to be critical in the protection of cells from reactive oxygen species.

AIM

In this case-control study we analysed the possible association between polymorphism in several cytosolic GST genes, air pollution and asthma development.

METHODS

Genotyping of GSTM1 and GSTT1 genes was carried out by a multiplex PCR; GSTA1, GSTO1, GSTO2, GSTP1 polymorphisms were determined using the PCR-RFLP method. Data on atmospheric pollutants were collected by the regional air-quality monitoring network.

RESULTS

Among all the polymorphisms studied, the frequencies of GSTA1, GSTM1, GSTO2 and GSTT1 genotypes found in the group of asthmatic patients seem to differ from the frequencies of those found in the control group. Air pollutants were analysed and the air quality parameters considered proved to be significantly different, and therefore suitable for this study.

CONCLUSION

The final result of this research should hopefully lead to a better understanding of gene-environment interactions, so allowing earlier prediction and diagnosis of asthma disease and providing an efficient means of prevention.

Lack of association of glutathione-S-transferase omega 1(A140D) and omega 2 (N142D) gene polymorphisms with urinary arsenic profile and oxidative stress status in arsenic-exposed population

Individual variability in arsenic metabolism is suggested to be associated with the effects of chronic arsenic exposure on health. Glutathione-S-transferase omega (GSTO) 1 and 2 are known to have the activity of monomethyl arsenate [MMA(V)] reductase, which is the rate-limiting enzyme for the biotransformation of inorganic arsenic. This study was conducted to investigate the relationship between polymorphisms in the GSTO1 and GSTO2 genes and arsenic metabolism and oxidative stress status in Chinese populations chronically exposed to different levels of arsenic in drinking water. Two polymorphisms (GSTO1*A140D and GSTO2*N142D) with relatively higher mutation frequencies in the Chinese population were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The allele frequencies of 140D and 142D in the entire study population were 0.17 and 0.25, respectively. There were no significant differences in the urinary arsenic profile, the blood reduced glutathione (GSH) levels, the blood superoxide dismutase (SOD) activity, or the urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels between the study subjects with different genotypes of GSTO1*A140D or GSTO2*N142D. Multivariate analysis revealed that there was no association between the urinary profile or oxidative stress status and the polymorphism of GSTO1*A140D or GSTO2*N142D. Collectively, polymorphisms in GSTO1 or GSTO2 do not appear to contribute to the large individual variability in arsenic metabolism or susceptibility to arsenicosis.