GSTO2*N142D gene polymorphism associated with hypothyroidism in Italian patients

Glutathione-Dependent Pathways in Cancer Cells

The most abundant tripeptide-glutathione (GSH)-and the major GSH-related enzymes-glutathione peroxidases (GPxs) and glutathione S-transferases (GSTs)-are highly significant in the regulation of tumor cell viability, initiation of tumor development, its progression, and drug resistance. The high level of GSH synthesis in different cancer types depends not only on the increasing expression of the key enzymes of the γ-glutamyl cycle but also on the changes in transport velocity of its precursor amino acids. The ability of GPxs to reduce hydroperoxides is used for cellular viability, and each member of the GPx family has a different mechanism of action and site for maintaining redox balance. GSTs not only catalyze the conjugation of GSH to electrophilic substances and the reduction of organic hydroperoxides but also take part in the regulation of cellular signaling pathways. By catalyzing the S-glutathionylation of key target proteins, GSTs are involved in the regulation of major cellular processes, including metabolism (e.g., glycolysis and the PPP), signal transduction, transcription regulation, and the development of resistance to anticancer drugs. In this review, recent findings in GSH synthesis, the roles and functions of GPxs, and GST isoforms in cancer development are discussed, along with the search for GST and GPx inhibitors for cancer treatment.

The Role of Glutathione Transferase Omega-Class Variant Alleles in Individual Susceptibility to Ovarian Cancer

The tumor microenvironment is affected by reactive oxygen species and has been suggested to have an important role in ovarian cancer (OC) tumorigenesis. The role of glutathione transferases (GSTs) in the maintenance of redox balance is considered as an important contributing factor in cancer, including OC. Furthermore, GSTs are mostly encoded by highly polymorphic genes, which further highlights their potential role in OC, known to originate from accumulated genetic changes. Since the potential relevance of genetic variations in omega-class GSTs (GSTO1 and GSTO2), with somewhat different activities such as thioltransferase and dehydroascorbate reductase activity, has not been clarified as yet in terms of susceptibility to OC, we aimed to investigate whether the presence of different GSTO1 and GSTO2 genetic variants, individually or combined, might represent determinants of risk for OC development. Genotyping was performed in 110 OC patients and 129 matched controls using a PCR-based assay for genotyping single nucleotide polymorphisms. The results of our study show that homozygous carriers of the GSTO2 variant G allele are at an increased risk of OC development in comparison to the carriers of the referent genotype (OR1 = 2.16, 95% CI: 0.88-5.26, p = 0.08; OR2 = 2.49, 95% CI: 0.93-6.61, p = 0.06). Furthermore, individuals with GST omega haplotype H2, meaning the concomitant presence of the GSTO1*A and GSTO2*G alleles, are more susceptible to OC development, while carriers of the H4 (*A*A) haplotype exhibited lower risk of OC when crude and adjusted haplotype analysis was performed (OR1 = 0.29; 95% CI: 0.12-0.70; p = 0.007 and OR2 = 0.27; 95% CI: 0.11-0.67; p = 0.0054). Overall, our results suggest that GSTO locus variants may confer OC risk.

The Polymorphisms in GSTO Genes (GSTO1 rs4925, GSTO2 rs156697, and GSTO2 rs2297235) Affect the Risk for Testicular Germ Cell Tumor Development: A Pilot Study

Members of the omega class of glutathione transferases (GSTs), GSTO1, and GSTO2, catalyze a range of reduction reactions as a part of the antioxidant defense system. Polymorphisms of genes encoding antioxidant proteins and the resultant altered redox profile have already been associated with the increased risk for testicular germ cell cancer (GCT) development. The aim of this pilot study was to assess the individual, combined, haplotype, and cumulative effect of GSTO1rs4925, GSTO2rs156697, and GSTO2rs2297235 polymorphisms with the risk for testicular GCT development, in 88 patients and 96 matched controls, through logistic regression models. We found that carriers of the GSTO1*C/A*C/C genotype exhibited an increased risk for testicular GCT development. Significant association with increased risk of testicular GCT was observed in carriers of GSTO2rs2297235*A/G*G/G genotype, and in carriers of combined GSTO2rs156697*A/G*G/G and GSTO2rs2297235*A/G*G/G genotypes. Haplotype H7 (GSTO1rs4925*C/GSTO2rs2297235*G/GSTO2rs156697*G) exhibited higher risk of testicular GCT, however, without significant association (p > 0.05). Finally, 51% of testicular GCT patients were the carriers of all three risk-associated genotypes, with 2.5-fold increased cumulative risk. In conclusion, the results of this pilot study suggest that GSTO polymorphisms might affect the protective antioxidant activity of GSTO isoenzymes, therefore predisposing susceptible individuals toward higher risk for testicular GCT development.

Puerarin enhances intestinal function in piglets infected with porcine epidemic diarrhea virus

Puerarin has been reported to be an excellent antioxidant, anti-inflammatory and antimicrobial agent, but the potential effect of puerarin on porcine epidemic diarrhea virus (PEDV) is unclear. This study aimed to determine whether puerarin could alleviate intestinal injury in piglets infected with PEDV. A PEDV (Yunnan province strain) infection model was applied to 7-day-old piglets at 104.5 TCID50 (50% tissue culture infectious dose). Piglets were orally administered with puerarin at the dosage of 0.5 mg/kg body weight from day 5 to day 9. On day 9 of the trial, piglets were inoculated orally with PEDV. Three days later, jugular vein blood and intestinal samples were collected. Results showed puerarin reduced morbidity of piglets infected with PEDV. In addition, puerarin reduced the activities of aspartate aminotransferase and alkaline phosphatase, the ratio of serum aspartate aminotransferase to serum alanine aminotransferase, the number of white blood cells and neutrophils, and the plasma concentrations of interleukin-6, interleukin-8 and tumor necrosis factor-α, as well as protein abundances of heat shock protein-70 in PEDV-infected piglets. Moreover, puerarin increased D-xylose concentration but decreased intestinal fatty acid-binding protein concentration and diamine oxidase activity in the plasma of piglets infected with PEDV. Puerarin increased the activities of total superoxide dismutase, glutathione peroxidase and catalase, while decreasing the activities of myeloperoxidase and concentration of hydrogen peroxide in both the intestine and plasma of PEDV-infected piglets. Puerarin decreased mRNA levels of glutathione S-transferase omega 2 but increased the levels of nuclear factor erythroid 2-related factor 2. Furthermore, puerarin increased the abundance of total eubacteria (16S rRNA), Enterococcus genus, Lactobacillus genus and Enterobacteriaceae family in the intestine, but reduced the abundance of Clostridium coccoides in the caecum. These data indicate puerarin improved intestinal function in piglets infected by PEDV and may be a promising supplement for the prevention of PEDV infection.

Assessment of GSTO1 (A140D) and GSTO2 (N142D) Gene Polymorphisms in Iranian Women with Polycystic Ovarian Syndrome

Background

Glutathione S-transferases (GSTs) protect cells from oxidative stress (OS). In humans, the GST omega class contains two expressed genes, GSTO1 and GSTO2. Because OS is involved in the pathogenesis of polycystic ovary syndrome (PCOS), the aim of this study was to investigate the relationship between GSTO1 A140D (rs4925) and GSTO2 N142D (rs156697) polymorphisms in PCOS patients.

Methods

175 PCOS patients and 161 healthy controls were selected among women in Kermanshah province, Iran. GSTO1 and GSTO2 were genotyped using allele-specific PCR (AS-PCR) and PCR-RFLP, respectively.

Results

For GSTO1, the DD genotype and the D allele led to 2.17- (P= 0.02) and 1.5-fold (P= 0.01) increases, respectively, in the odds ratios for PCOS. No significant difference was found between control and patient groups for the GSTO2 N142D genotype or allele frequency. GSTO1 and GSTO2 genotype interaction analysis showed that individuals with the GSTO1 AD or DD genotypes and the GSTO2 NN or DN genotypes had a 1.53-fold (P= 0.007) increase in PCOS risk over GSTO1 AA and GSTO2 DD individuals.

Conclusion

The GSTO1 A140D polymorphism is a risk factor for PCOS.

Concomitance of Polymorphisms in Glutathione Transferase Omega Genes Is Associated with Risk of Clear Cell Renal Cell Carcinoma

Glutathione S-transferases (GSTs), a superfamily of multifunctional enzymes, play an important role in the onset and progression of renal cell carcinoma (RCC). However, novel GST omega class (GSTO), consisting of GSTO1-1 and GSTO2-2 isoenzymes, has not been studied in RCC yet. Two coding single nucleotide polymorphisms (SNPs) supposedly affect their functions: GSTO1*C419A (rs4925) causing alanine to aspartate substitution (*A140D) and GSTO2*A424G (rs156697) causing asparagine to aspartate substitution (*N142D), and have been associated with several neurodegenerative diseases and cancers. Functional relevance of yet another GSTO2 polymorphism, identified at the 5' untranslated (5'UTR) gene region (GSTO2*A183G, rs2297235), has not been clearly discerned so far. Therefore, we aimed to assess the effect of specific GSTO1 and GSTO2 gene variants, independently and in interaction with established risk factors (smoking, obesity and hypertension) on the risk for the most aggressive RCC subtype, the clear cell RCC (ccRCC). Genotyping was performed in 239 ccRCC patients and 350 matched controls, while plasma levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage, were determined by ELISA. As a result, combined effect of all three variant genotypes exhibited almost 3-fold risk of RCC development. Additionally, this association was confirmed at the haplotype level [variant GSTO1*A/GSTO2*G (rs156697)/GSTO2*G (rs2297235) haplotype], suggesting a potential role of those variants in propensity to RCC. Regarding the gene-environment interactions, variant GSTO2*G (rs156697) homozygous smokers are at higher ccRCC risk. Association in terms of oxidative DNA damage was found for GSTO2 polymorphism in 5'UTR and 8-OHdG. In conclusion, the concomitance of GSTO polymorphisms may influence ccRCC risk.

Effect of the GSTM1 gene deletion on glycemic variability, sympatho-vagal balance and arterial stiffness in patients with metabolic syndrome, but without diabetes

AIMS

An increased rate of cerebrovascular complications in patients with metabolic syndrome (MetS) has been reported. Previous studies demonstrated an association between glycemic variability (GV) and cerebrovascular reactivity (CRV) in MetS, thus suggesting a putative role of GV on cerebrovascular events. Although the pathophysiological mechanism linking GV to damage is still to be elucidated, evidence suggests oxidative stress plays a crucial role. Since functional variants in glutathione S-transferases (GST) genes modulate the cellular detoxification processes, the aim of this study was to elucidate the involvement of GSTs in MetS and investigating the correlation with GV, arterial stiffness, and sympatho-vagal (SV) balance.

METHODS

A hundred metabolic syndrome patients without diabetes underwent GST gene polymorphism analysis and a sub-sample 36 patients were randomly selected to investigate the correlation between GST gene polymorphisms and GV, and sympatho-vagal (SV) balance and arterial stiffness.

RESULTS

GSTM1 showed a significant association with several GV, arterial stiffness, and SV balance indexes. In particular, the GSTM1 deletion positively correlates with lower values of these indexes when compared to the presence of the gene.

CONCLUSIONS

Therefore, we suggested a global influence of GSTM1 deletion on the GV, arterial stiffness, and SV balance pathways in MetS patients, probably also interacting with AMP-activated protein kinase (AMPK) regulation. Our novel findings indicate GSTM1 could be a risk locus in MetS development and shed light novel scenarios on the role of glucose fluctuations in neurological impairments.

Association of GSTO1 and GSTO2 Polymorphism with Risk of End-Stage Renal Disease Development and Patient Survival

Background

Oxidative stress in patients with end-stage renal disease (ESRD) is associated with long-term cardiovascular complications. The cytosolic family of glutathione S-transferases (GSTs) is involved in the detoxication of various toxic compounds and antioxidant protection. GST omega class members, GSTO1 and GSTO2 possess, unlike other GSTs, dehydroascorbate reductase and deglutathionylation activities. The aim of this study was to clarify the role of genetic polymorphisms of GSTO1 (rs4925) and GSTO2 (rs156697) as risk determinants for ESRD development, as well as in the survival of these patients.

Methods

A total of 199 patients and 199 healthy subjects were included in the study and genotyped for both GSTO1 and GSTO2 polymorphism. Protein thiol and carbonyl groups as markers of protein oxidative damage were determined spectrophotometrically. Cox proportional hazard model and Kaplan-Meier analysis were performed to investigate the role of GSTO1 and GSTO2 genetic polymorphism on mortality of ESRD patients during the follow-up period (36 month).

Results

Individuals carrying the variant GSTO2 GG genotype were at 2.45-fold higher risk of ESRD development compared to the wild type GSTO2 AA genotype (OR=2.45; 95%CI=1.18–5.07; p=0.016). The results of GSTO1/GSTO2 haplotype analysis showed that the haplotype combination of GSTO1 (*A)/GSTO2 (*A) (GSTO1 variant/GSTO2 wild type allele) was protective for ESRD (OR=0.23 95%CI=0.12-0.44, p=0.001). Patients carrying at least one GSTO1 reference allele have shorter mean overall (Log rank=2.844, p =0.241) and cardiovascular survival probability (Log rank=4.211, p=0.122).

Conclusions

GSTO polymorphisms have been shown to act as significant markers in assessing the risk of ESRD development and patients’ survival.

GSTA1 gene variation associated with gestational hypertension and its involvement in pregnancy-related pathogenic conditions

OBJECTIVE(S)

Glutathione S-transferases (GSTs) are the main phase II enzymes involved in the cellular detoxification. Through phase I and phase II detoxification reactions, the cell is able to detoxify endogenous and exogenous toxic compounds. In this study, we focused our attention on the GSTA1*-69C/T gene polymorphism (rs3957357) in order to explore its involvement in the genetic predisposition to gestational hypertension (GH).

STUDY DESIGN

The case-control population consists of 195 subjects. The genotyping of the GSTA1*-69C/T was performed by using an RFLP-PCR technique. We calculated odds ratios (ORs), adjusted for the confounding variables, to estimate the association between GSTA1 and GH.

RESULTS

Significant allelic differences in GSTA1*-69C/T are present between GH women and pregnant women without cardiovascular complications (p<0.05). Specifically, we observed that the dominant genetic model best explains the observed genetic association, according to the Akaike information criterion and the Bayesian information criterion.

CONCLUSION(S)

Our study highlighted a significant association between the GSTA1 gene and the risk of GH in Italian patients. In particular, the -69C/T variant was significantly associated with disease risk. Since previous studies indicated that this GSTA1 polymorphism is associated with different pregnancy-related conditions, our finding supports the notion that GSTA1 may play a key role during pregnancy.

Explorative genetic association study of GSTT2B copy number variant in complex disease risks

BACKGROUND

Glutathione S-transferases (GSTs) are the main phase II enzymes involved in cellular detoxification. Through phase I and phase II detoxification reactions, the cell is able to detoxify endogenous and exogenous toxic compounds.

AIMS

This study focused attention on the GSTT2B copy number variant (CNV) in order to explore its involvement in the genetic pre-disposition to asthma, Alzheimer's disease (AD), allergic rhinitis (AR), essential hypertension (EH), hypothyroidism and recurrent miscarriage (RM).

METHODS

The study population consists of 1225 individuals divided into six case-control groups. The genotyping of the GSTT2B CNV was performed by using a duplex-PCR. Odds Ratios (ORs) were calculated, adjusting for the confounding variables, to estimate the association between GSTT2B CNV and the disease status.

RESULTS

The χ(2)-test and ORs did not show any association between this genetic marker and pathological phenotypes.

CONCLUSION

The data highlights that GSTT2B CNV is not associated with the investigated complex diseases in Italian patients. However, further investigations are necessary to replicate these findings in larger sample sizes and to explore other health-related phenotypes.

GSTO1*C/GSTO2*G haplotype is associated with risk of transitional cell carcinoma of urinary bladder

PURPOSE

To clarify the role of genetic polymorphisms of GSTO1 (rs4925) and GSTO2 (rs156697) in individual susceptibility to urinary bladder cancer.

METHODS

Case-control study consisting of 187 patients with histologically confirmed transitional cell carcinoma (TCC) of urinary bladder and 140 age- and gender-matched cancer-free controls was carried out. Genotyping of GSTO1 and GSTO2 was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

We found that carriers of mutant GSTO2*G/G genotype were at increased risk of the development of TCC (OR 2.6, 95% CI 1.2-5.8, p = 0.041), while GSTO1 rs4925 polymorphism was not significantly associated with TCC risk (p = 0.450). According to smoking status, smokers with GSTO2*G/G genotype had significantly higher risk of TCC of urinary bladder (OR 4.3, 95% CI 1.6-11.2, p = 0.003) compared to wild-type carriers with no smoking history. We further analyzed the effects of GSTO1/GSTO2 haplotypes on TCC risk, based on the linkage disequilibrium found for GSTO1 (rs4925) and GSTO2 (rs156697) (D' = 0.309, p = 0.001). The study subjects with GSTO1*C/GSTO2*G (GSTO1 wild-type/GSTO2 mutant) haplotype were at the highest risk of the development of transitional cell carcinoma of urinary bladder (OR 2.8, 95% CI 1.5-5.2, p = 0.002).

CONCLUSIONS

Our results indicate that GSTO1*C/GSTO2*G haplotype is associated with increased risk of TCC. The modifying effect of GSTO2*G/G genotype on individual susceptibility to TCC is more pronounced, when associated with smoking.

GSTA1*-69C/T and GSTO2*N142D as asthma- and allergy-related risk factors in Italian adult patients

1. Asthma and allergies are characterized by variable and subjective symptoms influenced by many genes, molecular mechanisms and environmental factors. The presence of inflammation and oxidative stress in the airways are important biochemical features of asthma and respiratory allergies. Glutathione S-transferase (GSTs) enzymes play an important role in cellular protection against inflammation, and functional genetic polymorphisms in GST genes show a significant association with asthma and allergy risk. Specifically, our previous study on asthmatic children highlighted GSTA1 and GSTO2 as novel susceptibility loci for asthma. 2. In the present study we focused our attention on GSTA1*-69C/T (rs3957357) and GSTO2*N142D (rs156697) polymorphisms to confirm our previous results in an independent adult study population and to clarify whether GSTA1 and GSTO2 gene polymorphisms are involved in a non-discriminative pathway towards asthma and respiratory allergy. 3. To accomplish this, we recruited 103 patients with respiratory allergies, 199 patients with asthma and 200 healthy controls. Genomic DNA extracted from buccal cells was screened for GSTA1*-69C/T and GSTO2*N142D single nucleotide polymorphisms. 4. The GSTA1*-69T and GSTO2*D142 variants are both associated with a significantly increased risk of asthma, whereas only GSTA1*-69C/T is significantly associated with allergies. These outcomes confirm the involvement of GSTO2 loci in asthma and suggest that GSTA1 is a common risk factor for asthma and allergies.