Ethnic differences in the prevalence of the homozygous deleted genotype of glutathione S-transferase theta

Analysis of null deletion polymorphism of glutathione S-transferase theta (GSTT-1), associated with anti-GSTT-1 antibodies development in transplantation

Glutathione S-transferase theta 1 (GSTT1) is an enzyme involved in phase II biotransformation processes and a member of a multigene family of detoxifying and clearing reactive oxygen species. GSTT1 is polymorphic like other biotransforming enzymes, allowing variability in hepatic conjugation processes. Immunological recognition of the GSTT1 alloantigen, as evidenced by donor-specific antibodies formation, has previously been observed in recipients lacking GSTT1 protein (called GSTT1-, GSTT*0, null phenotype or homozygous for the GSTT1 deletion) who receive liver or kidney transplants from GSTT1+ donors and is a risk factor for the development of de novo hepatitis following liver transplants from a GSTT1 expressing donor. Antibodies against GSTT1 are demonstrated in patients who are GSTT1 null and received a transplant from a GSTT1+ donor. Understanding the local population frequency of the GSTT1 deletion is of value in understanding the potential clinical risk of developing post-transplant complications, which can be attributed to the nonexpression of GSTT1. A population of 173 healthy donors of the Murcia Region in Southeast Spain was evaluated for a null allele of GSTT1 (n = 173). DNA was extracted, and GSTT-1 null allele detection was performed by real-time polymerase chain reaction. The frequency of the null GSTT1 genotype (nonexpression or deletion of the homozygous polymorphism of the GSTT1 protein) was 17.9% (n = 31 null allele GSTT1/173 total individuals). Our data suggest that the frequency of null GSTT1 mutations in our population in Southeast Spain is 17.9%, lower than in other Caucasoid populations. This would convert our recipient population into more susceptible to nonlocal potential organ donors and less susceptible to local donors. All recipients bearing this GSTT1 deletion homozygous would be without the protein and triggering an alloantigen in the case of transplantation with a donor without deletion.

Alcohol consumption, tobacco smoking, and subsequent risk of renal cell carcinoma: The JPHC study

The effects of alcohol consumption and tobacco smoking on renal cell carcinoma (RCC) incidence have not been well‐investigated in Asian populations. Here, we evaluated these effects in a large Japanese prospective cohort. We collected data on eligible participants in the Japan Public Health Center‐based Prospective Study, and undertook multivariable‐adjusted Cox proportional hazards regression to estimate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) of RCC incidence. We identified 340 cases (230 men and 110 women) among the 105 663 eligible participants (50 262 men and 55 741 women), who were followed for an average of 19.1 years, with a cumulative total of 2 020 364 person‐years. A slightly inverse but nonsignificant association was observed between alcohol drinking and RCC incidence. In contrast, the risk of RCC was increased in those with heavy smoking (≥40 pack‐years) when men and women were combined (HR 1.50; 95% CI, 1.01‐2.25). We identified no significant association between alcohol consumption and RCC incidence. In contrast, heavy smoking (≥40 pack‐years) was associated with a significant increase in incidence.

Using a large prospective cohort in Japan, we evaluated the effects of alcohol consumption and tobacco smoking on renal cell carcinoma (RCC). Our analyses showed no significant association between alcohol consumption and RCC incidence. In contrast, heavy smoking (≥40 pack‐years) was associated with a significant increase in incidence.

Differences in exposure to toxic and/or carcinogenic volatile organic compounds between Black and White cigarette smokers

OBJECTIVE

It is unclear why Black smokers in the United States have elevated risk of some tobacco-related diseases compared to White smokers. One possible causal mechanism is differential intake of tobacco toxicants, but results across studies are inconsistent. Thus, we examined racial differences in biomarkers of toxic volatile organic compounds (VOCs) present in tobacco smoke.

METHOD

We analyzed baseline data collected from 182 Black and 184 White adult smokers who participated in a randomized clinical trial in 2013-2014 at 10 sites across the United States. We examined differences in urinary levels of ten VOC metabolites, total nicotine equivalents (TNE), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), controlling for covariates such as cigarettes per day (CPD), as well as differences in VOCs per TNE to assess the extent to which tobacco exposure, and not metabolic factors, accounted for racial differences.

RESULTS

Concentration of metabolites of acrolein, acrylonitrile, ethylene oxide, and methylating agents were significantly higher in Blacks compared to Whites when controlled for covariates. Other than the metabolite of methylating agents, VOCs per TNE did not differ between Blacks and Whites. Concentrations of TNE/CPD and VOCs/CPD were significantly higher in Blacks. Menthol did not contribute to racial differences in VOC levels.

CONCLUSIONS

For a given level of CPD, Black smokers likely take in higher levels of acrolein, acrylonitrile, and ethylene oxide than White smokers. Our findings are consistent with Blacks taking in more nicotine and toxicants per cigarette smoked, which may explain their elevated disease risk relative to other racial groups.

Intake of total cruciferous vegetable and its contents of glucosinolates and isothiocyanates, glutathione S-transferases polymorphisms and breast cancer risk: a case-control study in China

Cruciferous vegetables contain high levels of glucosinolates (GSL) and isothiocyanates (ITC). ITC are known to induce glutathione S-transferases (GST) and thus exert their anticarcinogenic effects. This study explored the combined effects of cruciferous vegetable, GSL and ITC intake and GST polymorphisms on breast cancer risk. A total of 737 breast cancer cases and 756 controls were recruited into this case-control study. OR and 95 % CI were assessed by multivariable logistic regression. Higher cruciferous vegetable, GSL and ITC intakes were inversely associated with breast cancer risk, with adjusted OR of 0·48 (95 % CI 0·35, 0·65), 0·54 (95 % CI 0·40, 0·74) and 0·62 (95 % CI 0·45, 0·84), respectively. Compared with women carrying the GSTP1 rs1695 wild AA genotype and high cruciferous vegetable, GSL or ITC intake, carriers of the AA genotype with low cruciferous vegetable, GSL and ITC intake had greater risk of breast cancer, with adjusted OR of 1·43 (95 % CI 1·01, 1·87), 1·34 (95 % CI 1·02, 1·75) and 1·37 (95 % CI 1·05, 1·80), respectively. Persons with the GSTM1-null genotype and lower intake of cruciferous vegetables, GSL and ITC had higher risk of breast cancer than those with the GSTM1-present genotype and higher intake, with OR of 1·42 (95 % CI 1·04, 1·95), 1·43 (95 % CI 1·05, 1·96) and 1·45 (95 % CI 1·06, 1·98), respectively. Among women possessing the GSTT1-present genotype, low intake of cruciferous vegetables, GSL or ITC was associated with higher risk of breast cancer. But these interactions were non-significant. This study indicated that there were no significant interactions between cruciferous vegetable, GSL or ITC intake and GST polymorphisms on breast cancer risk.

GSTs polymorphisms are associated with epigenetic silencing of CDKN2A gene in esophageal squamous cell carcinoma

Esophageal cancer is the eighth most common cancer and the sixth most frequent cause of cancer mortality worldwide. Exposure to polycyclic aromatic hydrocarbons formed by incomplete combustion of organic matter is an important risk factor. Genetic polymorphisms in genes encoding PAH-metabolizing enzymes like glutathione S-transferases (GSTM1, GSTP1, GSTT1) which conjugate glutathione to PAHs for reduction of oxidative stress may affect an individual's response to PAH exposure. Genomic DNA from 50 esophageal squamous cell carcinoma patients extracted from peripheral blood. PCR-RFLP technique was employed to determine GSTM1, GSTT1, and GSTP1 polymorphisms. Aberrant promoter methylation of CDKN2A was applied by methylation-specific PCR technique. Concentration of urinary 1-hydroxypyrene was determined using a HPLC system. About 38.7% showed the null GSTM1 genotype (54% cases and 13% controls), 23.7% showed GSTT1 null genotype (30% cases and 13% controls), and 62.5% were GSTP1 A/A genotype (66% cases and 56% controls). Polymorphic variants of GSTM1 and GSTT1 were significantly associated with aberrant methylation of CDKN2A gene. The null state of GSTT1 was significantly associated with high concentrations of 1-OHP in urea (p < 0.01). There was significant association between methylated states of CDKN2A and high concentrations of 1-OHP in urine (p < 0.01). We identified significant association between polymorphism of GSTs genes and epigenetic silencing of tumor suppressor gene CDKN2A in esophageal squamous cell carcinoma.

CYP1A1, GSTT1, IL-6 and IL-8 transcription and IL-6 secretion on umbilical endothelial cells from hypertensive pregnant women: Preliminary results

The impact of pregnancy hypertension in the offspring endothelia remains unknown. We evaluated the transcriptional expression of four genes that participate in the process of endothelial dysfunction using umbilical vein endothelial cell cultures (HUVEC) from healthy pregnant women (PW) and those with hypertensive disorders (HD). The cytochrome P450 1A1 (CYP1A1), gluthathione S-transferase subtype T1 (GSTT1), interleukin 6 (IL-6) and 8 (IL-8) mRNA and IL-6 protein levels were assessed. IL-6 and IL-8 transcripts were significantly reduced in HUVEC obtained from HD women. Our results suggest that a hypertensive environment in utero modifies the transcriptional expression of key inflammatory molecules in the newborn.

Esophageal cancer genetics in South Africa

Esophageal cancer (EC) is an extremely aggressive cancer with one of the highest mortality rates. The cancer is generally only diagnosed at the later stages and has a poor 5-year survival rate due to the limited treatment options. China and South Africa are two countries with a very high prevalence rate of EC. EC rates in South Africa have been on the increase, and esophageal squamous cell carcinoma is the predominant subtype and a primary cause of cancer-related deaths in the black and male mixed ancestry populations in South Africa. The incidence of EC is highest in the Eastern Cape Province, especially in the rural areas such as the Transkei, where the consumption of foods contaminated with Fusarium verticillioides is thought to play a major contributing role to the incidence of EC. China is responsible for almost half of all new cases of EC globally. In China, the prevalence of EC varies greatly. However, the two main areas of high prevalence are the southern Taihang Mountain area (Linxian, Henan Province) and the north Jiangsu area. In both countries, environmental toxins play a major role in increasing the chance that an individual will develop EC. These associative factors include tobacco use, alcohol consumption, nutritional deficiencies and exposure to environmental toxins. However, genetic polymorphisms also play a role in predisposing individuals to EC. These include single-nucleotide polymorphisms that can be found in both protein-coding genes and in non-coding sequences such as miRNAs. The aim of this review is to summarize the contribution of genetic polymorphisms to EC in South Africa and to compare and contrast this to the genetic polymorphisms observed in EC in the most comprehensively studied population group, the Chinese.

Gene-gene-environment interactions of prenatal exposed to environmental tobacco smoke, CYP1A1 and GSTs polymorphisms on full-term low birth weight: relationship of maternal passive smoking, gene polymorphisms, and FT-LBW

OBJECTIVE

To examine the interaction effects of prenatal exposed to environmental tobacco smoke (ETS) and genotypes of cytochrome P4501A1 (CYP1A1), glutathione S-transferases (GSTs) on the risk of full-term low birth weight (FT-LBW).

STUDY DESIGN

We conducted a case-control study among pregnant women at two Women and Children's Hospitals in Guangdong, China (n = 910). Information was collected through interview, medical records review, and blood lab tests. Maternal selfreport and serum cotinine concentration were combined to define prenatal exposed to ETS. Logistic regression approach was applied for statistical analysis.

RESULTS

Our results showed that regardless of genotypes, prenatal exposed to ETS significantly increased the risk of FT-LBW. Then, two-way interactions showed increased prevalence of FT-LBW in prenatal exposed to ETS mothers with the CYP1A1 variant genotype (MspI "CC"), or with GSTT1-null genotype. Furthermore, three-way interactions showed that women with CYP1A1 variant (MspI "TC" or BsrDI "AG") genotypes and GSTT1 "null" genotype had higher risk to give birth of FT-LBW. Additionally, among nonexposed ETS mothers, genotype did not independently confer adverse effects on FT-LBW.

CONCLUSIONS

Our results revealed that prenatal exposed to ETS is independently associated with FT-LBW while gene polymorphisms of CYP1A1 and GSTs merely play modified roles in this process. This study extends understanding of three-way interaction, and stresses the need to tobacco control toward pregnant women for better pregnant outcomes.

Trimodal GSTT1 and GSTM1 Genotyping Assay by Real-Time PCR

The GSTT1 and GSTM1 genes are characterized by the existence of a GST*0 null allele responsible for a lack of enzyme activity, with the respective null genotypes GSTT1*0/0 and GSTM1*0/0. The three resulting genotypes (GSTs*1/1, *1/0 and *0/0) are associated with a trimodal distribution of glutathione-conjugator activity. Previous epidemiological studies have only evaluated the cancer risk associated with the GST null genotype relative to the two GST carrier geno-® types (GSTs1*1/1 and *1/0). We developed GSTT1 and GSTM1 TaqMan real-time quantitative PCR assays to discriminate each of the three genotypes, with the albumin gene (ALB) as reference. The mean NGSTT1*1/1 value was 1.0 (95% confidence interval 0.80–1.20). The mean NGSTT1*1/0 value was 0.48 (95% CI 0.36–0.60). One (3.4%) of the 29 DNA samples yielded the GSTM1*1/1 genotype (NGSTM1*1/1 = 1), a frequency in keeping with the Hardy-Weinberg distribution. The mean NGSTM1*1/0 value was 0.50 (95% CI 0.42–0.58). All GSTT1*0/0 and GSTM1*0/0 samples yielded NGST values of 0 (Ct = 40); the frequencies of these genotypes (27.6% and 55.2%, respectively) were in keeping with published data. The GSTT1 and GSTM1 real-time PCR assays described here unambiguously discriminate each of the three existing genotypes which should be valuable for assessing the relative risk of cancer associated with each of the three GST genotypes.

A study of the association of glutathione S-transferase M1/T1 polymorphisms with susceptibility to vitiligo in Egyptian patients

BACKGROUND

The association of glutathione S-transferases M1/T1 (GSTM1/T1) null polymorphisms with vitiligo was proposed in several studies including two Egyptian studies with contradictory results.

OBJECTIVE

The aim here was to assess the association between GSTM1/T1 null polymorphisms and the susceptibility to vitiligo in a larger sample of Egyptian patients with generalized vitiligo.

METHODS

This study included 122 vitiligo patients and 200 healthy controls that were age, and gender matched. Assessment of GSTM1/T1 gene polymorphisms was done using a multiplex polymerase chain reaction (PCR).

RESULTS

Increased odds of generalized vitiligo was observed with the null genotypes of GSTM1 and GSTT1 polymorphisms (P<0.05). Controls with GSTM1 null/GSTT1+ heterozygosis presented with a 2.97 odds protection from having generalized vitiligo (OR=2.97, 95%CI=1.1-7.7) (P=0.02) compared with patients.

STUDY LIMITATIONS

Small sample size of patients.

CONCLUSIONS

This study showed a significant trend towards an association with the combination of the GSTM1/GSTT1 double null polymorphism and generalized vitiligo. Individuals with GSTM1 null/GSTT1+ heterozygosis have a 2.97 odds protection from having generalized vitiligo compared with patients. It was is the first time, to our knowledge, that such an association has been reported.

Distribution of genetic variants of oxidative stress metabolism genes: Paraoxonase 1 (PON1) and Glutathione S-transferase (GSTM1/GSTT1) in a population from Southeastern Mexico

BACKGROUND

Paraoxonase 1 (PON1) and glutathione S-transferases (GSTs) are involved in the biotransformation of xenobiotics. Variation in the enzyme concentration and activity suggests individual differences for the degree of protection against oxidative stress.

AIM

This study analysed the distribution of SNPs Q192R, L55M (PON1) and variants in GSTM1 and GSTT1 genes in a population from Southeastern Mexico.

SUBJECTS AND METHODS

One hundred and fifty-one Mexican Mestizo healthy volunteers were included. PON1 polymorphisms were determined by Taqman allele discrimination real time-PCR, whereas GSTM1 and GSTT1 genes were determined with a multiplex PCR-based method.

RESULTS

All genotypes were in Hardy-Weinberg equilibrium, except for GSTM1. The genotypic distributions of Q192R and L55M were 22% QQ, 48% QR, 30% RR, 62% LL, 34% LM and 4% MM, respectively, whereas the allele frequencies were 0.46 (Q), 0.54 (R), 0.79 (L) and 0.21 (M). The most frequent haplotype was R/L (46.7%). It was found that 31% and 9% of the individuals had the GSTM1 and GSTT1 null genotype, respectively. The frequency of the combined null genotype GSTM1*0/GSTT1*0 was 4.64%.

CONCLUSION

The results showed that the frequencies of polymorphisms of PON1, GSTM1 and GSTT1 in the Yucatán population differ to those observed in other ethnic groups and provide useful data for epidemiological studies.

Analyses of Genetic Variations of Glutathione S-Transferase Mu1 and Theta1 Genes in Bangladeshi Tannery Workers and Healthy Controls

Glutathione S-transferases (GSTs) belong to a group of multigene detoxification enzymes, which defend cells against oxidative stress. Tannery workers are at risk of oxidative damage that is usually detoxified by GSTs. This study investigated the genotypic frequencies of GST Mu1 (GSTM1) and GST Theta1 (GSTT1) in Bangladeshi tannery workers and healthy controls followed by their status of oxidative stress and total GST activity. Of the 188 individuals, 50.0% had both GSTM1 and GSTT1 (+/+), 12.2% had GSTM1 (+/-), 31.4% had GSTT1 (-/+) alleles, and 6.4% had null genotypes (-/-) with respect to both GSTM1 and GSTT1 alleles. Among 109 healthy controls, 54.1% were double positive, 9.2% had GSTM1 allele, 32.1% had GSTT1 allele, and 4.6% had null genotypes. Out of 79 tannery workers, 44.3% were +/+, 16.8% were +/-, 30.5% were -/+, and 8.4% were -/-. Though the polymorphic genotypes or allelic variants of GSTM1 and GSTT1 were distributed among the study subjects with different frequencies, the differences between the study groups were not statistically significant. GST activity did not vary significantly between the two groups and also among different genotypes while level of lipid peroxidation was significantly higher in tannery workers compared to controls irrespective of their GST genotypes.

Association of CYP1A1, GSTM1 and GSTT1 gene polymorphisms with risk of non-small cell lung cancer in Andhra Pradesh region of South India

BACKGROUND

Lung cancer is one of the most preventable causes of death globally both in developed and developing countries. Although it is well established that smokers develop lung cancer, there are some smokers who are free from the disease risk. The predisposition to lung cancer is attributed to genetic polymorphisms in xenobiotic metabolizing genes. Reports on assessment of xenobiotic metabolizing genes like Cytochrome P 450 1A1 (CYP1A1), Glutathione -S -transferase M1 (GSTM1) and T1 (GSTT1) polymorphisms from India are meagre, and reports from Andhra Pradesh are lacking.

METHODS AND RESULTS

Assessment of polymorphisms in CYP1A1, GSTM1 and GSTT1 in NSCLC patients and healthy individuals specific to population of Andhra Pradesh, a South Indian state was attempted by multiplex PCR and RFLP, and this is the first study which tried to correlate oxidative stress with the polymorphisms in xenobiotic metabolizing genes. Results showed that CYP1A1 m1 'CC' genotype was significantly associated with lung cancer susceptibility with a 2.3-fold risk, CYP1A1 m2 'AG' gene polymorphisms with 8.8-fold risk and GSTT1 (-/-) genotype demonstrated a twofold risk of disease susceptibility.

CONCLUSIONS

A combined role of genetic polymorphisms and smoking status can be attributed for the cause of lung cancer. Further, the association between oxidative stress and genetic polymorphisms showed a correlation between GSTT1 and super oxide dismutase activity; CYP1A1 m1, m2 and GSTT1 with glutathione peroxidase activity; CYP1A1 m1 and GSTM1 with melondialdehyde levels; and CYP1A1 m1 and GSTT1 with 8-oxo-7,8-dihydro-2'-deoxyguanosine. A higher risk of lung cancer seems to be associated with combined gene polymorphisms of phase I and phase II enzymes than that ascribed to single gene polymorphism.

Associations of air pollution exposure with blood pressure and heart rate variability are modified by oxidative stress genes: A repeated-measures panel among elderly urban residents

BACKGROUND

Oxidative stress has been suggested as a major cause of elevated blood pressure (BP) and reduced heart rate variability (HRV) due to air pollution. We hypothesized that the associations of air pollution exposure with BP and HRV are modified by oxidative stress gene polymorphisms.

METHODS

Between 2008 and 2010, we conducted up to 5 surveys of 547 elderly participants, measured their BP and HRV, and genotyped 47 single nucleotide polymorphisms (SNPs) in 18 oxidative stress genes. Linear mixed models were constructed to evaluate the associations of particulate matter ≤10 μm, nitrogen dioxide, and sulfur dioxide with BP and HRV, as well as the modifications of these associations by the genotyped SNPs.

RESULTS

Single-SNP analyses revealed interactions between air pollution and 15 SNPs (for BP) and 33 SNPs (for HRV) (all, P for interaction < 0.05). When we generated genetic risk scores for BP and HRV, using the SNPs with interactions in the single-SNP models, we found that associations of air pollution exposure with BP and HRV were modified by the genetic risk scores (P for interaction < 0.05).

CONCLUSIONS

These results strongly suggest that the associations of air pollution with BP and HRV are mediated by oxidative stress pathways.

Benzene Uptake and Glutathione S-transferase T1 Status as Determinants of S-Phenylmercapturic Acid in Cigarette Smokers in the Multiethnic Cohort

Research from the Multiethnic Cohort (MEC) demonstrated that, for the same quantity of cigarette smoking, African Americans and Native Hawaiians have a higher lung cancer risk than Whites, while Latinos and Japanese Americans are less susceptible. We collected urine samples from 2,239 cigarette smokers from five different ethnic groups in the MEC and analyzed each sample for S-phenylmercapturic acid (SPMA), a specific biomarker of benzene uptake. African Americans had significantly higher (geometric mean [SE] 3.69 [0.2], p<0.005) SPMA/ml urine than Whites (2.67 [0.13]) while Japanese Americans had significantly lower levels than Whites (1.65 [0.07], p<0.005). SPMA levels in Native Hawaiians and Latinos were not significantly different from those of Whites. We also conducted a genome-wide association study in search of genetic risk factors related to benzene exposure. The glutathione S-transferase T1 (GSTT1) deletion explained between 14.2-31.6% (p = 5.4x10-157) and the GSTM1 deletion explained between 0.2%-2.4% of the variance (p = 1.1x10-9) of SPMA levels in these populations. Ethnic differences in levels of SPMA remained strong even after controlling for the effects of these two deletions. These results demonstrate the powerful effect of GSTT1 status on SPMA levels in urine and show that uptake of benzene in African American, White, and Japanese American cigarette smokers is consistent with their lung cancer risk in the MEC. While benzene is not generally considered a cause of lung cancer, its metabolite SPMA could be a biomarker for other volatile lung carcinogens in cigarette smoke.

Association between glutathione S-transferase M1/T1 gene polymorphisms and susceptibility to endometriosis: A systematic review and meta-analysis

Endometriosis is a polygenic/multifactorial disease caused by interactions between multiple genes and the environment. Findings from studies evaluating the association between the glutathione S-transferase (GST) M1/T1 null genotype and susceptibility to endometriosis are inconsistent. This meta-analysis updated and reevaluated the possible associations between GSTM1, GSTT1 and combined GSTM1/GSTT1 (null genotype versus wild-type) gene polymorphisms and susceptibility to endometriosis. The PubMed, Embase and Chinese BioMedical Literature databases and Google Scholar were searched for case-control genetic association studies on GSTM1/GSTT1 (null genotype versus wild-type) gene polymorphisms and endometriosis in comparison with non-endometriosis or healthy controls. Fixed-effect and random-effect meta-analytical techniques were conducted for the outcome measure and subgroup analyses. The meta-analysis demonstrated significant associations between the GSTM1 [odds ratio (OR)=1.56; 95% confidence interval (CI): 1.25–1.95; P<0.0001), GSTT1 (OR=1.31; 95% CI: 1.02–1.68; P=0.037) and GSTM1/GSTT1 (OR=1.68; 95% CI: 1.29–2.17; P<0.0001) null genotypes and increased risk for endometriosis. The results suggest that the GSTM1, GSTT1, and combined GSTM1/GSTT1 null genotypes increase susceptibility to endometriosis. Additional well-designed studies and precise analyses are warranted to confirm these findings.

Resistance to cancer chemotherapy: failure in drug response from ADME to P-gp

Cancer chemotherapy resistance (MDR) is the innate and/or acquired ability of cancer cells to evade the effects of chemotherapeutics and is one of the most pressing major dilemmas in cancer therapy. Chemotherapy resistance can arise due to several host or tumor-related factors. However, most current research is focused on tumor-specific factors and specifically genes that handle expression of pumps that efflux accumulated drugs inside malignantly transformed types of cells. In this work, we suggest a wider and alternative perspective that sets the stage for a future platform in modifying drug resistance with respect to the treatment of cancer.

Glutathione-S-Transferase Deletions and Non-arteritic Anterior Ischemic Optic Neuropathy

In this study, we aimed at investigating the association between glutathione-S-transferase (GSTM1 and GSTT1) deletion genotypes and susceptibility to non-arteritic anterior ischemic optic neuropathy (NAION). We hope our findings may contribute to the understanding NAION pathogenesis and provide some clues for the prevention and treatment of optic diseases. The NAION group contains 113 subjects (33 males and 80 females, mean age 55.3 ± 9.8). And 98 subjects were enrolled in the control group (32 males and 66 females, mean age 56.7 ± 10.2). The individuals involved in the study were matched by gender and age to obtain two homogenous groups. GSTM1- and GSTT1- genotype and the combined genotype were investigated. The genotype distributions in NAION patients were compared with those in the controls. Significantly altered intraocular pressure (IOP) and cup-to-disc ratio (CDR) was detected between NAION patients and controls. An increased risk of NAION was observed among individuals with GSTM1- (P < 0.001). No significant difference was confirmed for GSTT1- (P = 0.290). Individuals with GSTM1-/GSTT1- have a higher susceptibility to NAION (P < 0.001); the GSTM1-/GSTT1+ genotype also had a significantly higher frequency in patients than in controls (P = 0.004). But the genotype of GSTM1+/GSTT1- seems to have no connection with NAION (P = 0.476). In conclusion, in this study, we confirmed the connection between NAION and GSTM1- genotype. But no significant association was observed between GSTT1- genotype and NAION susceptibility. In further analysis regarding combined genotype, a trend of protective effect was detected for GSTT1+ genotype. It is indicated by our result that oxidative compounds might play an important part in the pathogenesis of NAION.

Glutathione S-transferase θ1 polymorphism contributes to lung cancer susceptibility: A meta-analysis of 26 case-control studies

The GSTT1 gene encodes a key enzyme involved in the metabolism of xenobiotics and its polymorphisms have been associated with individual susceptibility to various malignancies. Numerous molecular epidemiological studies have been performed to investigate the association between GSTT1 gene polymorphisms and lung cancer susceptibility; however, the results of previous studies were inconsistent. Therefore, the aim of the present study was to conduct a meta-analysis in order to derive a more precise estimation of the association in the East Asian populations. The meta-analysis included 7,415 lung cancer cases and 6,084 controls from 26 published studies in East Asia, which were selected from the PubMed and China National Knowledge Infrastructure databases, up to March 20, 2014. Using crude odds ratios (ORs) with 95% confidence intervals (CIs), a statistically significant association was identified between the GSTT1 null genotype and lung cancer in the East Asian populations (OR=1.17; 95% CI, 1.09–1.25; P_{heterogeneity}=0.003). Furthermore, subgroup analyses revealed that the lung cancer risk in smokers carrying the GSTT1 null genotype was significantly increased compared with non-smokers (OR=1.71; 95% CI, 1.04–2.81; P_{heterogeneity}=0.002). Thus, the GSTT1 null genotype may increase the risk of lung cancer among the East Asian populations.

The impact of GSTM1/GSTT1 polymorphism for the risk of oral cancer

OBJECTIVES

Since development of oral squamous cell cancer (OSCC) is triggered by various noxa, different variants of the antioxidant glutathione S-transferases (GSTs) can counteract toxic compounds (e.g., tobacco smoke). Because different polymorphisms of GST are known to have an increased sensitivity to carcinogenic agents, the aim of this study was to analyze whether GSTM1 or GSTT1 polymorphisms increase the risk for the development of OSCC.

MATERIALS AND METHODS

GSTM1 and GSTT1 polymorphism was examined in healthy volunteers (n = 93) and in patients with OSCC (n = 100) by PCR after brush biopsy of oral mucosa. Odds ratio (OR) was calculated to evaluate the risk of oral cancer development.

RESULTS

GSTM1 and GSTT1 deletion was found in 57% (53/93) and 18% (17/93), respectively, in healthy patients, while the OSCC group showed 57% (57/100) for GSTM1 deletion and 22% (22/100) with a deletion of GSTT1. Odds ratio for GSTM1 polymorphism was 1.00 and for GSTT1 1.26. Comparing smokers and nonsmokers with GSTM1 deletion polymorphism, OR was 4.35, while smokers without GSTM1 deletion showed an OR of 1.45. Adapting these data to the smoking habits of the general population in Germany, the OR was 9.25 for smokers with a GSTM1 deletion and OR 6.68 for smokers without a GSTM1 deletion. In smokers with GSTT1 deletion polymorphism, OR was 1.6 (adapted to the smoking habits of the general population: OR 6.16) and 3.16 (OR 8.56) in smokers without deletion in GSTT1 gene.

CONCLUSIONS

Analysis of GST-M1 polymorphism in smokers could help to identify patients with a higher risk for the development of oral cancer.

CLINICAL RELEVANCE

Early detection of OSCC due to a close meshed monitoring program for patients with GST-M1 polymorphism could help to improve the patient outcome. For polymorphism investigations, the oral brush biopsy is a sufficient method to gain DNA material.

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.

Effects of glutathione S-transferase M1 and T1 deletions on epilepsy risk among a Tunisian population

Glutathione-S-transferases enzymes are involved in the detoxification of several endogenous and exogenous substances. In this present study, we evaluated the effects of two glutathione-S-transferase polymorphisms, (GSTM1 and GSTT1) on epilepsy risk susceptibility in a Tunisian population. These polymorphisms were analyzed in 229 healthy subjects and 98 patients with epilepsy, using a polymerase chain reaction (PCR). Odds ratio (ORs) was used for analyzing results. The study results demonstrated that individuals with the GSTM1 null genotype were at an increased risk of developing epilepsy [OR=3.80, 95% confidence interval (CI) (2.15-4.78)], whereas no significant effects were observed between individuals with GSTT1 null genotype and epilepsy risk [OR=1.15, 95% CI (0.62-2.12)]. These genotyping finding revealed that the absence of GSTM1 activity could be contributor factor for the development of epilepsy disease.

Gene-environment interaction among GSTT1, PON2 polymorphisms and organic solvents on gestational age in a Chinese women cohort

PURPOSE

To investigate interactions on gestational age among two environmental risk factors and four maternal genetic polymorphisms: organic solvents, passive smoking, CYP1A1 rs4646903 (MspI), EPHX1 rs2234922 (His139Arg), GSTT1 and PON2 rs12026 (Ala148Gly).

METHODS

A pregnant women cohort was conducted at Beijing Yanshan Petrochemical Corporation, and 1,097 mothers with live singleton births were included in analysis. Generalized Multifactor Dimensionality Reduction (GMDR) method was used to explore interactions among these factors with adjustment for important potential confounders. Multiple linear regression models were used to estimate the association of interaction with gestational age.

RESULTS

A three-factor model of organic solvents, GSTT1 and PON2 rs12026 had the highest testing balanced accuracy (57.05 %) and best cross-validation consistency (10/10). Compared with organic solvents unexposed mothers with GSTT1 non-null genotype and PON2 rs12026 CC genotype, organic solvents exposed mothers with GSTT1 null genotype and PON2 rs12026 CG + GG genotype had the largest reduction in gestational age (-0.36 weeks, 95%CI: -0.70 to -0.02). The significant reductions in different groups were from 0.24 weeks to 0.36 weeks.

CONCLUSIONS

Maternal genetic susceptibility GSTT1 and PON2 rs12026 could significantly modify the association of organic solvents with gestational age.

The association between gene polymorphisms of glutathione S-transferase T1/M1 and type 1 diabetes in Slovak children and adolescents

BACKGROUND

Considering a dramatic increase in the incidence of type 1 diabetes (T1D) worldwide, current research focuses on complex etiology of T1D where immune system, environmental and genetic factors play a significant role. Glutathione S-transferase family of enzymes protects tissue from oxidative damage which is discussed in the context of T1D. The aim of the study was to investigate an association of glutathione S-transferase mu 1 (GST M1) and glutathione S-transferase theta 1 (GST T1) polymorphisms with type 1 diabetes.

METHODS

163 children, 116 with type 1 diabetes and 47 healthy controls, at the age 6-19 years were enrolled to the study. Basic anthropometric, biochemical parameters and GST T1 diabetes and M1 polymorphisms were established in each subject.

RESULTS

Subjects with T1D had significantly lower concentration of uric acid compared to the healthy subjects (212.85 +/- 57.10 micromol/l vs. 269.57 +/- 72.53; p < 0.001). GST T1 null genotype was more frequent in patients with diabetes compared to the healthy controls (36.2% vs. 21.3%) and represented 2.1-fold increased risk of T1D of borderline statistical significance (OR = 2.1; 95% Cl = 0.949-4.648; p = 0.06). GST T1 null/M1 wild genotype combination was more frequent in patients with diabetes (25.9% vs. 10.6%) and represented 2.9-fold increased risk for T1D development (OR = 2.93; 95% CI = 1.061-8.095; p = 0.032).

CONCLUSION

The study indicates that GST T1 null genotype and GST T1 null/M1 wild combination could be considered a risk factor for type 1 diabetes development in Slovak children and adolescents.

Common polymorphic deletion of glutathione S-transferase theta predisposes to acquired aplastic anemia: Independent cohort and meta-analysis of 609 patients

Acquired aplastic anemia (AA) is a rare life-threatening bone marrow failure syndrome, caused by autoimmune destruction of hematopoietic stem and progenitor cells. Epidemiologic studies suggest that environmental exposures and metabolic gene polymorphisms contribute to disease pathogenesis. Several case-control studies linked homozygous deletion of the glutathione S-transferase theta (GSTT1) gene to AA; however, the role of GSTT1 deletion remains controversial as other studies failed to confirm the association. We asked whether a more precise relationship between the GSTT1 null polymorphism and aplastic anemia could be defined using a meta-analysis of 609 aplastic anemia patients, including an independent cohort of 67 patients from our institution. We searched PubMed, Embase, and the Cochrane Database for studies evaluating the association between GSTT1 null genotype and development of AA. Seven studies, involving a total of 609 patients and 3,914 controls, fulfilled the eligibility criteria. Meta-analysis revealed a significant association of GSTT1 null genotype and AA, with an OR = 1.74 (95% CI 1.31-2.31, P < 0.0001). The effect was not driven by any one individual result, nor was there evidence of significant publication bias. The association between AA and GSTT1 deletion suggests a role of glutathione-conjugation in AA, possibly through protecting the hematopoietic compartment from endogenous metabolites or environmental exposures. We propose a model whereby protein adducts generated by reactive metabolites serve as neo-epitopes to trigger autoimmunity in aplastic anemia.

The neurological effects of methyl bromide intoxication

Used primarily as a fumigant or as a substrate in chemical processes, methyl bromide is a highly toxic gas. The gas is usually absorbed by inhalation and effects on the lungs, gastrointestinal tract, skin, and brain are seen. Numerous instances of acute and chronic neurologic injury have been reported: acute poisoning results in seizures, myoclonus, ataxia or cerebral oedema beginning as early as 30 min after exposure while subacute or chronic intoxication presents with diverse slowly progressive neurological and neurobehavioral symptoms. Serum bromide levels may be elevated, but often return rapidly to normal. Electroencephalography may show frontally-predominant slow waves or polyspikes with following slow wave, and MRI reveals characteristic involvement in the dentate nucleus of the cerebellum, the brainstem, and the splenium of the corpus callosum. Symmetric and selective lesions in characteristic sites are observed on imaging and on histopathological examination. These are likely produced by methylation of intracellular lipids, protein and glutathione; production of toxic metabolites; defective neurotransmitter function; and abnormal oxidative phosphorylation. This article reviews the toxic effects of this gas, the pathophysiology and symptoms of its effects on the nervous system, and characteristic findings on MRI; and presents an illustrative case of methyl bromide intoxication due to exposure at a factory producing the compound commercially.

The glutathione S-transferase T1 deletion is associated with susceptibility to multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) occurs as a result of interaction between genetic and environmental factors. Recent data support the view that oxidative damage is one of an early event in MS tissue injury. The safe elimination of reactive oxygen species and toxins via glutathione S-transferase (GST) pathways is required in order to protect cells against reactive oxygen-induced damage. The aim of our study was to analyze the possible association of GSTM1 and GSTT1 gene polymorphisms with the susceptibility and clinical parameters of MS, in 455 consecutive patients and 366 controls.

METHODS

A multiplex polymerase chain reaction (PCR) was used to detect the deletions in GSTM1 and GSTT1 genes.

RESULTS

Patients with MS had significantly higher frequency of GSTT1 null genotype compared to controls (37.36% vs. 21.86%, respectively, p<0.0001, adjusted OR 2.13 (1.56-2.90)), as well as double deletions (15.38% vs. 10.38%, respectively, p<0.05). The carriers of GSTM1 deletion had significantly earlier onset of MS compared to the wild-type carriers (28.31 ± 8.45 vs. 30.64 ± 9.30 years, respectively, p = 0.03).

CONCLUSION

This study suggests the potential pathogenic role of GSTT1 deletion on MS susceptibility. There are no similar data published so far, yet this study should be replicated in other populations.

Polymorphism of CYP1A1 gene and susceptibility to childhood acute lymphoblastic leukemia in Egypt

The origin of acute lymphoblastic leukemia (ALL) may be explained by a combination of genetic susceptibility and environmental exposure. We aimed to study the frequency of CYP1A1 allelic variants in Egyptian patients with ALL, to evaluate their role in the development of ALL and to correlate these allelic variants with clinical and biological characteristics of the patients. Polymorphism of CYP1A1*2A, *2B and *4 alleles was examined in 186 Egyptian children with ALL and 200 normal individuals using polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP). A higher prevalence of the CYP1A1*4 allele was found in patients with ALL than in the normal population (19.4%vs. 10.0%, odds ratio [OR] = 2.160, 95% confidence interval [CI] = 1.200-3.89, p = 0.01), especially in the homozygous variant (OR = 6.6, 95% CI = 2.23-19.58, p = 0.001) and in male patients (p = 0.005), particularly those aged 2-10 years (OR = 5.214, 95% CI = 1.535-17.706, p = 0.008). CYP1A1*2A showed a significant difference between age groups (p = 0.046), with a higher incidence in the 10-17-year-old group (21.1%). Multivariate analysis showed that only the CYP1A1*4 allele remained as a probable independent risk factor for ALL development (OR = 2.250, 95% CI = 1.244-4.069; p = 0.007). Our results suggest that polymorphic variants in the CYP1A1*4 gene may increase the risk of childhood ALL, particularly in male patients aged 2-10 years.

Glutathione S-transferase M1 and T1 polymorphisms: susceptibility and outcomes in muscle invasive bladder cancer patients

BACKGROUND

We investigated whether genetic polymorphisms in the glutathione S transferase mu (GSTM1) and theta (GSTT1) genes modulated risk, disease progression and survival in primary muscle invasive bladder cancer (MIBC).

METHODS

GSTM1 and GSTT1 polymorphisms were analysed by multiplex polymerase chain reaction (PCR) using blood genomic DNA in 110 MIBC patients and 220 gender- and age-matched healthy controls. The influence of the genetic polymorphisms on patient survival was evaluated by Kaplan-Meier survival curves and Cox Proportional Hazard models. We also evaluated whether cigarette smoking and treatment modality modified the association between genotype and prognosis.

RESULTS

GSTM1-null individuals exhibited increased risk for MIBC and an association with cigarette smoking. GSTT1-null subjects showed significant disease progression and cancer-specific death. In the combined analysis, GSTT1-null genotype was an independent risk factor for disease progression and cancer specific death regardless of GSTM1 genotype. Significant differences in progression-free survival (PFS) and cancer-specific survival (CSS) were seen based on GSTT1 genotype. The survival impact of the GSTT1 genotype was only valid for smokers. The GSTT1-null genotype was an independent prognostic factor for shorter PFS in patients who received chemotherapy and those who did not undergo radical cystectomy. By multivariate Cox regression analysis, GSTT1-null genotype was a predictive factor for disease progression and cancer specific survival regardless of treatment modality.

CONCLUSIONS

The GSTM1-null genotype plays an important role in genetic susceptibility to MIBC and the GSTT1-null genotype is associated with disease progression and shorter survival in MIBC.

Glutathione transferases, regulators of cellular metabolism and physiology

BACKGROUND

The cytosolic glutathione transferases (GSTs) comprise a super family of proteins that can be categorized into multiple classes with a mixture of highly specific and overlapping functions.

SCOPE OF REVIEW

The review covers the genetics, structure and function of the human cytosolic GSTs with particular attention to their emerging roles in cellular metabolism.

MAJOR CONCLUSIONS

All the catalytically active GSTs contribute to the glutathione conjugation or glutathione dependant-biotransformation of xenobiotics and many catalyze glutathione peroxidase or thiol transferase reactions. GSTs also catalyze glutathione dependent isomerization reactions required for the synthesis of several prostaglandins and steroid hormones and the catabolism of tyrosine. An increasing body of work has implicated several GSTs in the regulation of cell signaling pathways mediated by stress-activated kinases like Jun N-terminal kinase. In addition, some members of the cytosolic GST family have been shown to form ion channels in intracellular membranes and to modulate ryanodine receptor Ca(2+) channels in skeletal and cardiac muscle.

GENERAL SIGNIFICANCE

In addition to their well established roles in the conjugation and biotransformation of xenobiotics, GSTs have emerged as significant regulators of pathways determining cell proliferation and survival and as regulators of ryanodine receptors that are essential for muscle function. This article is part of a Special Issue entitled Cellular functions of glutathione.

GSTM1 polymorphism modifies the effect of smoking on calcaneal quantitative ultrasound in young men

Evidence suggests that smoking adversely affects bones. Glutathione S-transferases (GSTs) are important in the detoxification of tobacco smoke compounds. This study investigated the influence of GSTM1 and GSTT1 genetic polymorphisms on the effects on bone induced by tobacco smoking in young men. In total, 231 Chinese men aged 20-39 years were assessed by a cross-sectional study. Calcaneal quantitative ultrasound (QUS) was measured. Smoking information was obtained using a questionnaire. Genotypes were determined for null alleles of GSTM1 and GSTT1. Smoking was inversely associated with speed of sound (SOS) and bone quality index (BQI) among subjects with GSTM1 null genotype (β = -0.28, 95% CI, -34.01 to -8.65 and β = -0.30, 95% CI, -16.41 to -4.49, respectively), but not among those with the allele present (β = -0.02, 95% CI, -15.01 to 12.59 and β = -0.09, 95% CI, -8.75 to 3.02, respectively). P for interaction = 0.04 for SOS and 0.08 for BQI. No interaction was found between the GSTT1 polymorphism and smoking. The results showed that GSTM1 deficiency may increase the adverse effect of smoking on calcaneal QUS in young men, suggesting an interaction between metabolic genes and tobacco smoke in bone detoxification.

Association of manganese superoxide dismutase and glutathione S-transferases genotypes with myocardial infarction in patients with type 2 diabetes mellitus

AIM

In the present study we investigated the association between genetic polymorphisms with functional effects on redox regulation: Val16Ala of manganese superoxide dismutase (MnSOD), polymorphic deletions of glutathione S-transferases M1 (GSTM1) and T1 (GSTT1) and Ile105Val of glutathione S-transferase P1 (GSTP1) and myocardial infarction (MI) in a group of patients with type 2 diabetes mellitus.

METHODS

The study population consisted of 463 Caucasian subjects with type 2 diabetes mellitus of more than 10 years' duration: 206 patients with MI and 257 patients with no history of coronary artery disease (CAD). Genotypes were determined by polymerase chain reaction (PCR) with restriction fragment length polymorphism (RFLP) and with multiplex PCR.

RESULTS

The genotype distributions of tested single nucleotide polymorphisms did not show significant difference between cases and controls. After adjustment for age, gender, smoking, BMI, duration of diabetes and lipid parameters carriers of GSTM1/GSTT1-null haplotype showed an increased risk for MI (OR=3.22, 95% CI 1.37-5.04, p=0.03).

CONCLUSIONS

The GSTM1/GSTT1 haplotype might be a genetic risk factor for MI in patients with type 2 diabetes mellitus.

Oxidative stress induced in the workers of natural gas refineries, no role for GSTM1 and GSTT1 polymorphisms

Oxidative stress has an important role in the pathophysiology of many occupational diseases. In this controlled exposure study, the intensity of oxidative stress biomarkers was assessed in the workers of natural sweet and sour gas refineries (SwGR and SoGR, respectively) and compared with controls. In addition, the role of gluthatione S-transferase M1 (GSTM1)-null and GSTT1-null polymorphisms on the intensity of oxidative stress and liver function tests (LFTs) was investigated. Blood samples were taken and measured for lipid peroxidation (LPO) level, total antioxidant capacity (TAC) and total thiol molecules (TTMs). GSTM1- and GSTT1-null genotypes were determined using polymerase chain reaction. LPO was significantly ( p < 0.05) higher in the workers of SoGR. TAC was significantly lower in SwGR subjects ( p < 0.001). TTMs were significantly lower in SoGR and SwGR subjects. Among LFTs, activities of aspartate aminotransferase and alanine aminotransferase but not alkaline phosphatase were elevated significantly ( p < 0.001) in SoGR subjects. Multivariate linear regression revealed no association between studied polymorphisms, oxidative stress biomarkers, and LFTs. These results indicate that working in the SoGR and SwGR can lead to oxidative stress and abnormal LFTs. Continuous monitoring of natural gas workers for probable ongoing problems is therefore suggested.

Association of a deletion of GSTT2B with an altered risk of oesophageal squamous cell carcinoma in a South African population: a case-control study

Background

Polymorphisms in the Glutathione S-transferase genes are associated with altered risks in many cancers, but their role in oesophageal cancer is unclear. Recently a 37-kb deletion polymorphism of GSTT2B that reduces expression of GSTT2 has been described. We evaluated the influence of the GSTT1 and GSTT2B deletion polymorphisms, and the GSTP1 Ile105Val polymorphism (rs1695) on susceptibility to oesophageal squamous cell carcinoma (OSCC) in the Black and Mixed Ancestry populations of South Africa.

Methods and Results

The GSTT1, GSTT2B and GSTP1 variants were genotyped in 562 OSCC cases and 907 controls, and tested for association with OSCC and for interaction with smoking and alcohol consumption. Linkage disequilibrium (LD) between the deletions at GSTT1 and GSTT2B was determined, and the haplotypes tested for association with OSCC. Neither the GSTT1 deletion nor the GSTP1 Ile105Val polymorphism was associated with OSCC risk in the Black or Mixed Ancestry populations. The GSTT2B deletion was not associated with OSCC risk in the Black population, but was associated with reduced risk of OSCC in the Mixed Ancestry population (OR = 0.71; 95% CI 0.57–0.90, p = 0.004). Case-only analysis showed no interaction between the GST polymorphisms and smoking or alcohol consumption. LD between the neighboring GSTT1 and GSTT2B deletions was low in both populations (r²_Black = 0.04; r²_MxA = 0.07), thus these deletions should be assessed independently for effects on disease risk.

Conclusions

Although there was no association between the GSTT1 deletion polymorphism or the GSTP1 Ile105Val polymorphism with OSCC, our results suggest that the presence of the recently described GSTT2B deletion may have a protective effect on the risk of OSCC in the Mixed Ancestry South African population. This is the first report of the contribution of the GSTT2B deletion to cancer risk.

Identification of the GST-T1 and GST-M1 null genotypes using high resolution melting analysis

Glutathione S-transferases, including GST-T1 and GST-M1, are known to be involved in the phase II detoxification pathways for xenobiotics as well as in the metabolism of endogenous compounds. Polymorphisms in these genes have been linked to an increased susceptibility to carcinogenesis and associated with risk factors that predispose to certain inflammatory diseases. In addition, GST-T1 and GST-M1 null genotypes have been shown to be responsible for interindividual variations in the metabolism of arsenic, a known human carcinogen. To assess the specific GST genotypes in the Mexican population chronically exposed to arsenic, we have developed a multiplex High Resolution Melting PCR (HRM-PCR) analysis using a LightCycler480 instrument. This method is based on analysis of the PCR product melting curve that discriminates PCR products according to their lengths and base sequences. Three pairs of primers that specifically recognize GST-T1, GST-M1, and β-globin, an internal control, to produce amplicons of different length were designed and combined with LightCycler480 High Resolution Melting Master Mix containing ResoLight, a completely saturating DNA dye. Data collected from melting curve analysis were evaluated using LightCycler480 software to determine specific melting temperatures of individual melting curves representing target genes. Using this newly developed multiplex HRM-PCR analysis, we evaluated GST-T1 and GST-M1 genotypes in 504 DNA samples isolated from the blood of individuals residing in Zimapan, Lagunera, and Chihuahua regions in Mexico. We found that the Zimapan and Lagunera populations have similar GST-T1 and GST-M1 genotype frequencies which differ from those of the Chihuahua population. In addition, 14 individuals have been identified as carriers of the double null genotype, i.e., null genotypes in both GST-T1 and GST-M1 genes. Although this procedure does not distinguish between biallelic (+/+) and monoallelic (+/-) genotypes, it can be used in an automated workflow as a simple, sensitive, and time and money saving procedure for rapid identification of the GST-T1 and GST-M1 positive or null genotypes.

Association of genetic polymorphism of glutathione S-transferase (GSTM1, GSTT1, GSTP1) with bladder cancer susceptibility

The glutathione-S-transferases (GSTs) comprise a class of enzymes that detoxify carcinogenic compounds by conjugating glutathione to facilitate their removal. Polymorphisms in GSTM1, GSTT1, and GSTP1 genes have been related to risk for bladder cancer. Studies focusing on GSTs gene variants relationship with the risk of bladder cancer have produced conflicting and inconsistent results. We examine the association between genetic polymorphism of glutathione S-transferase P1, GSTM1, GSTT1 genes and development of bladder transitional cell carcinoma (TCC). The study population consisted of 166 histologically confirmed male bladder TCC cases and 332 healthy male controls. Genotyping was done using the polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method and also investigated combined gene interactions. The GSTP1 Val/Val genotype was significantly associated with bladder cancer (OR = 4.32, 95% CI: 2.64-6.34), whereas the association observed for GSTM1 null (OR = 1.32, 95% CI: 0.82-2.62; P = 0.67) and GSTT1 null genotype (OR = 1.18, 95% CI: 0.79-1.67; P = 0.74) did not reach statistical significance. There was a significant multiple interaction between GSTM1, GSTT1, and GSTP1 genotypes in risk of bladder cancer (P for interaction = 0.02). The risk associated with the concurrent presence of GSTM1 positive and GSTP1 Ile/Val or Val/Val (OR = 3.71, 95% CI: 2.34-5.54) and GSTT1 positive and GSTP1 Ile/Val or Val/Val (OR = 2.66, 95% CI: 1.54-4.72) was statistically significant. Patients carrying GSTP1 Val/Val genotype were at increased risk for developing high-grade (OR = 7.68, 95% CI: 4.73-19.25) and muscle invasive (OR = 10.67, 95% CI: 6.34-21.75) bladder cancer. High risk for bladder TCC also was observed with respect to combined GSTT1 null/GSTP1 Ile/Val or Val/Val (OR = 4.76, 95% CI: 2.68-18.72) and GSTM1 null/GSTT1 null/GSTP1 Ile/Val or Val/Val (OR = 6.42, 95% CI: 4.76-14.72) genotype variant. This study suggests that the GSTP1 polymorphism and its combination with GSTM1, and GSTT1 may be associated with bladder cancer susceptibility in the Iranian population. Further confirmation in large population-based studies is needed.

Genetic polymorphisms of glutathione S-transferases are associated with ulcerative colitis in central China

The present study aimed to investigate the association between genetic polymorphisms of glutathione S-transferases (GSTs) and susceptibility to ulcerative colitis (UC) in central China. The prevalence of GSTM1, GSTT1, and GSTP1 gene polymorphisms were examined using polymerase chain reaction methods in 270 consecutive UC patients and 623 age- and sex-matched healthy controls. The frequencies of the GSTM1(null) and GSTT1(null) as well as GSTP1 (Val/Val) genotypes were significantly higher in UC patients than in the controls (70.74% vs. 41.74%, P = 0.0001; 64.82% vs. 47.19%, P = 0.0001; and 48.89% vs. 34.35%, P = 0.0004, respectively). When the UC patients were stratified according to clinical features, we found that the frequencies of the GSTT1(null) and GSTP1 (Val/Val) genotypes but not the GSTM1(null) genotype were significantly higher in patients with distal colitis than in extensive colitis (P = 0.0007, P = 0.001, and P = 0.271, respectively). However, these variant GST genotypes were not significantly linked to severity of the disease (P > 0.05). GST variant genotypes are strongly correlated with prevalence and extent but not with severity of UC in the Hubei Han population in central China.

An update on ethnic differences in drug metabolism and toxicity from anti-cancer drugs

INTRODUCTION

Based on recent emerging evidence of inter-ethnic differences in drug response and toxicity, ethnic diversity in pharmacokinetics, pharmacogenomics and clinical outcomes are being increasingly investigated. Ultimately, this will promote improved understanding of inter-individual differences in the pharmacokinetics and tolerance of cytotoxic drugs.

AREAS COVERED

This article reviews potential explanations for the observed ethnic differences in treatment outcomes and provides clinical data to support this concept. A literature search was implemented on PubMed and PharmGKB to investigate the areas of ethnic differences in pharmacogenomics, pharmacogenetics and clinical outcomes of cancer therapies.

EXPERT OPINION

There has been a relative paucity of clinical evidence linking genetic polymorphisms of genes encoding drug-metabolizing enzymes to the pharmacokinetics, pharmacodynamics and tolerance of anti-cancer drugs. Future research should focus on studies using large sample sizes, in the hope that they will provide results of high clinical significance. Due to the potential for ethnic differences to impact on both toxicities and benefits of systemic cancer therapies, the development of new therapeutic agents should include patients from diverse geographical ancestries in each phase of drug development.

Coffees rich in chlorogenic acid or N-methylpyridinium induce chemopreventive phase II-enzymes via the Nrf2/ARE pathway in vitro and in vivo

Recently, the coffee constituents 5-O-caffeoylquinic acid (CGA) and N-methylpyridinium (NMP) were identified as inducers of the Nrf2/antioxidant-response element (ARE) detoxifying pathway under cell-culture condition. To study the impact of CGA and NMP on the Nrf2-activating properties of a complex coffee beverage, two different model coffees were generated by variation of the roasting conditions: a low-roast coffee rich in CGA and a heavy-roast low in CGA but containing high levels of NMP. Activation of the Nrf2/antioxidant-response element pathway was monitored in vitro and in vivo.