Glutathione S-transferase M1 and T1 null genotype frequency in chronic myeloid leukaemia

Association Between the Individual and Combined Effects of the GSTM1 and GSTT1 Polymorphisms and Risk of Leukemia: A Meta-Analysis

Background: Fourteen meta-analyses reported the individual effects of the GSTM1 and GSTT1 polymorphisms on leukemia risk. However, over 40 studies were not included in previously published meta-analyses. Moreover, one key aspect was that previous meta-analyses did not conduct the false-positive test on the aforementioned issues. Furthermore, previous meta-analyses did not observe the combined effects of GSTM1 present/null and GSTT1 present/null polymorphism with leukemia risk. Therefore, we conducted the current study to further analyze these associations. Objectives: This study aimed to investigate the association between the individual and combined effects of the GSTM1 present/null and GSTT1 present/null polymorphisms and the risk of leukemia. Methods: A meta-analysis was performed applying Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines. Moreover, false-positive report probability (FPRP) and Bayesian false discovery probability (BFDP) were applied to investigate the false-positive results. Results: The individual GSTM1 and GSTT1 null genotypes and combined effects of the two genes were associated with a significantly increased leukemia risk in overall and several subgroup analyses, such as Asians, Caucasians, and so on. Then, further analysis was conducted using FPRP and BFDP. Significant associations were considered as "positive" results on the GSTM1 null genotype with leukemia risk in overall populations (FPRP < 0.001 and BFDP = 0.006), Asians (FPRP < 0.001 and BFDP < 0.001), and East Asian population (FPRP < 0.001 and BFDP = 0.002). For the GSTT1 null genotype, significant associations were regarded "positive" results in overall populations, acute myeloid leukemia (AML), Asians, and East Asian population. For the combined effects of the GSTM1 and GSTT1 polymorphisms, significant associations were also considered "positive" results in the overall analysis of Asians, Indians, and East Asian population. Conclusion: This study strongly indicates that the individual GSTM1 and GSTT1 null genotypes and combined effects of the two genes are associated with increased leukemia risk in Asians, especially in the East Asian population; the GSTT1 null genotype is associated with increased AML risk; the combined effects of the two genes are associated with increased leukemia risk in Indians.

Combined GSTT1 Null, GSTM1 Null and XPD Lys/Lys Genetic Polymorphisms and Their Association with Increased Risk of Chronic Myeloid Leukemia

Purpose

Glutathione S-transferases (GSTT1 and GSTM1) are instrumental in detoxification process of activated carcinogens. Nucleotide excision repair is carried out by DNA helicase encoded by xeroderma pigmentosum group D (XPD) genes and aberrations in the XPD gene predisposes to increased risk of cancer. The present study aimed to investigate GSTT1, GSTM1 and XPD polymorphisms in newly diagnosed chronic myeloid leukemia (CML) patients and to examine the association of these polymorphisms with the risk of developing CML.

Patients and Methods

This case–control study was carried out from June 2019 to August 2021 involving 150 newly diagnosed patients with CML and an equal number of randomly selected age- and sex-matched healthy individuals. A multiplex-PCR assay was used to genotype GSTT1 null and GSTM1 null polymorphisms. XPD gene polymorphism was detected by PCR-RFLP using predesigned gene-specific primers.

Results

GSTT1 and GSTM1 null polymorphisms were detected in 42.7% and 61.3% of cases, respectively, compared to 18% and 35.3% for controls. The combination of both GST null polymorphisms revealed a significant association with CML. Frequencies of XPD Lys751Gln genotypes in cases were 62.7% heterozygous Lys/Gln, 24% homozygous Lys/Lys and 13.3% homozygous Gln/Gln, while in the controls were 74.7%, 20%, and 5.3%, respectively. Significant differences were also noted regarding the combination of GSTT1/GSTM1 null with XPD Lys/Lys, and GSTM1 null with XPD Lys/Lys.

Conclusion

In conclusion, GSTT1 null, GSTM1 null and XPD polymorphisms showed positive association with the risk of development of CML. Furthermore, age and gender did not exhibit any association with the studied polymorphisms, while CML phases were associated with GSTT1 null polymorphism.

Genetic Polymorphism of GSTP1, GSTM1 and GSTT1 Genes and Susceptibility to Chronic Myeloid Leukaemia

BACKGROUND

The development of cancer results from an imbalance between exposure to carcinogens and the capacity of various enzyme systems engaged in activation or in the detoxification of xenobiotics. The aim of the present study is to investigate the association of GSTP1, GSTM1 and GSTT1 gene polymorphisms in susceptibility to Chronic Myeloid Leukaemia (CML).

METHODS

A total of 200 CML patients and 100 controls were enrolled in a case-control study with GSTM1 and GSTT1 analysis with PCR and GSTP1 analysis with PCR-RFLP.

RESULTS

The GSTT1 null genotype was significantly higher among CML patients suggesting that this genotype is associated with an increased risk of CML. It was found in 42% of cases as compared with 21% of the controls, (OR =2.78, 95% CI: 1.59 - 4.85; p-value =0.000). The presence of the GSTT1 genotype may thus be considered a protective factor for CML. The frequency of individuals carrying GSTM1 null genotype was slightly higher in the control group but this difference was not statistically significant. The GSTM1 null genotype was present in 35% of control cases and 34% of the CML patients, (OR=0.975, 95%CI: 0.58-1.58;p-value=0.863). Individuals with a combined GSTM1 null/GSTT1null genotype had an estimated 2.85-fold increased risk of CML, but no associated risk between GSTP1 Ile 105 Val polymorphism and CML was found (OR=1.99, 95% CI: 0.40 - 9.32; p-value = 0.417).

CONCLUSIONS

No association between GSTP1 and GSTM1 with susceptibility to CML was found. GSTT1 genotype may be a protective factor for CML, while the null genotype shows association with developing CML.<br />.

Age- and gender-independent association of glutathione S-transferase null polymorphisms with chronic myeloid leukemia

The glutathione S-transferase (GST) genes encode enzymes that mediate the detoxification of xenobiotics by catalyzing the conjugation of glutathione (GSH) to xenobiotic substrates. The aim of the current study is to investigate the association between GSTT1 and GSTM1 polymorphisms and chronic myeloid leukemia (CML) among Sudanese patients. Patients with CML (n = 115) were recruited to the study from the Radiation and Isotope Centre Khartoum (RICK)-Sudan. Healthy individuals (n = 104) were included as controls. Genotyping of GSTT1 and GSTM1 polymorphisms was performed using multiplex PCR. Null deletions in the GSTT1 and GSTM1 genes are common in the Sudanese population (control group), with frequencies of 33.9% and 38.2%, respectively. The frequencies of GSTT1 (OR: 3.25, 95% CI: 1.87-5.65, p < 0.001) and GSTM1 (OR: 2.14, 95% CI: 1.25-3.67, p < 0.005) null genotypes were significantly higher in CML patients vs. controls. The distribution of GSTT1 and GSTM1 null polymorphisms was not different between male and female (p > 0.01) and young and old CML patients (p > 0.05). Hematological parameters were not affected by null polymorphisms in the patient group (p > 0.05). In addition, the frequency of GSTM1 null polymorphism was lower in advanced-phase CML patients compared to chronic-phase patients (p < 0.05). The GSTT1 and GSTM1 null polymorphisms are associated with CML among Sudanese patients, independently of their age and gender.

Role of glutathione-S-transferase M1 (GSTM1) and T1 (GSTT1) genes in the development and progress of chronic myeloid leukemia and in the formation of response to imatinib therapy

The effects of GSTM1 and GSTT1 gene deletion ("zero") polymorphisms on the risk of chronic myeloid leukemia development and progress and on response to imatinib monotherapy were studied in the representatives of the Russian nationality in the Vyatka region of Russia. Homozygotic carriership of GSTT1 "zero" allele was associated with a 3.66 times higher risk of chronic myeloid leukemia development in residents of the Vyatka region (OR=3.66, 95% CI=2.12-6.30; p<0.0001). Combinations of the "zero" GSTM1 and GSTT1 genotypes were risk factors indicating the probable disease progress and failure of high cytogenetic response after 12 months of imatinib therapy (400 mg daily).

Glutathione S-transferase gene polymorphisms and susceptibility to chronic myeloid leukemia

Glutathione S-transferase (GST), a phase II metabolizing enzyme, plays an important role in the cellar defense system, and its activity may modulate leukemia risk. A large body of evidence has shown the possible relevance of functional polymorphisms of the genes that encode GSTs μ, π, and θ (GSTM1, GSTP1, and GST1, respectively) to the genetic susceptibility of chronic myeloid leukemia (CML). Because of the lack of available conclusive data, we performed a meta-analysis of all relevant available studies to derive a more precise estimation of the relationship. A comprehensive literature search of PubMed and Web of Knowledge electronic databases was conducted to collect relevant studies until December 20, 2013, and the extracted data were statistically analyzed using Review Manager version 5.2. Finally, 16 eligible studies were identified in the literature. The GSTT1 null genotype was associated with an increased risk of CML, as were the double null GSTT1 and GSTM1 genotypes. These findings suggest that heritable GST status influences the risk of developing CML and that more attention should be paid to carriers of these susceptibility genes.

Polymorphic variation in glutathione-S-transferase genes and risk of chronic myeloid leukaemia in the Kashmiri population

Cancer is a complex disease and the genetic susceptibility to it could be an outcome of the inherited difference in the capacity of xenobiotic metabolizing enzymes. Glutathione-S-transferases (GSTs) are phase II metabolizing enzymes whose various genotypes have been associated with increased risk of different types of cancer. Null mutations caused by the deletion of the entire gene result in the absence of the enzymatic activity and increase in the risk of developing cancer including chronic myeloid leukaemia (CML). In the present case-control study we evaluated the effect of null mutations in GSTM1 and GSTT1 genes on the risk of developing CML. The study included 75 CML patients (43 males and 32 females; age (mean ± S.D) 42.3 ± 13.4 years) and unrelated non-malignant controls (76 male and 48 females; age (mean ± S.D) 41.5 ± 12.9). The distribution of GSTM1 and GSTT1 genotypes in CML patients and controls was assessed by multiplex-PCR method. Logistic regression was used to assess the relationship between GSTM1 and GSTT1 genotypes and risk of CML. Chi-square test was used to evaluate the trend in modulating the risk to CML by one or more potential high risk genotype. Although GSTM1 null genotype frequency was higher in CML patients (41%) than in the controls (35%), it did not reached a statistical significance (OD = 1.32, 95% CI: 0.73-2.40; P value = 0.4295). The frequency of GSTT1 null genotypes was higher in the CML patients (36%) than in the controls (21%) and the difference was found to be statistically significant (OD = 2.12, 95% CI: 1.12-4.02; P value = 0.0308). This suggests that the presence of GSTT1 genotype may have protective role against the CML. We found a statistically significant (OD = 3.09, 95% CI: 1.122-8.528; P value = 0.0472) interaction between the GSTM1 and GSTT1 null genotypes and thus individuals carrying null genotypes of both GSTM1 and GSTT1 genes are at elevated risk of CML.

Variations in glutathione-S-transferase genes influence risk of chronic myeloid leukemia

Glutathione S-transferases (GSTs) are phase II enzymes that detoxify hazardous xenobiotics including carcinogens. Inter-individual variations in GSTM1 and GSTT1 loci have been associated with several types of cancer, including leukemias. In this study, we investigated the possible association between GSTM1 and GSTT1 polymorphisms and susceptibility to chronic myeloid leukemia (CML) in a Turkish population. In a case-control study, 106 CML patients and 190 healthy controls were evaluated for GSTM1 and GSTT1 polymorphisms. GSTM1 null (GSTM1(-)) genotype frequencies in CML cases and controls were 45.3% and 42.6%, respectively. GSTT1 null (GSTT1(-)) genotype frequencies were 44.3% and 18.4%, respectively. The frequency of the GSTT1(-) genotype among CML patients was significantly higher than in controls [odds ratio (OR) 3.53, 95% confidence interval (CI) 2.08-6.00; P < 0.0001]. Individuals with the GSTM1(-) genotype did not have increased risk of CML [OR: 1.11; 95% CI: 0.69-1.80; P = 0.714]. The combined GSTM1(-)/GSTT1(-) genotype was significantly associated with risk of CML compared to the GSTM1(+) /GSTT1(+) genotype which was most frequent in both cases and controls [OR: 9.47; 95% CI: 3.61-24.87]. Similar findings have only been obtained in Turkish and Indian populations but not elsewhere. The GSTM1(+) /GSTT1(-) genotype was associated with a 2.5-fold increased risk compared with the GSTM1(-)/GSTT1(+) genotype, the second most frequent genotype (OR; 2.46; 95% CI: 1.17, 5.20), suggesting a complex interaction between GSTM1 and GSTT1. Our results indicate an association between the GSTT1(-) genotype, either alone or in combination with GSTM1(-) genotype, and risk of CML, suggesting a possible interaction between GSTM1 and GSTT1. These findings, which are possibly restricted to Turkey and India, warrant further research.

Association of glutathione S-transferase, EPHX, and p53 codon 72 gene polymorphisms with adult acute myeloid leukemia

Polymorphisms in genes encoding detoxification enzymes have been suggested as susceptibility factors for many solid tumors. However, their association with hematological malignancies is controversial. A case-control study was done to determine the association between glutathione S-transferase M1 (GSTM1), GSTT1, GSTP1, EPHX1, and p53 codon 72 polymorphisms as risk factors in 120 adult acute myeloid leukemia (AML) cases and 202 healthy controls by polymerase chain reaction-restriction fragment length polymorphism techniques. Data were analyzed using χ(2) and conditional logistic regression model. None of the polymorphisms studied alone was associated with increased risk for AML. However, the frequency of GSTT1 null genotype was higher among controls (28.7%) than AML cases (21.6%), which showed a protective effect of the null genotype (odds ratio = 0.58, 95% confidence interval: 0.33-1.05, p = 0.07). In a combined analysis, both EPHX1 (His113His) and GSTP1 (Ile/Val) genes imparted a fourfold risk for adult AML but did not reach statistical significance (odds ratio = 4.22, 95% confidence interval: 0.992-17.99, p = 0.05). These findings suggest that the etiology of adult AML cannot be explained by polymorphism at a single locus, perhaps because of complexity involved in the metabolism of diverse xenobiotic compounds, and therefore, multiple gene-gene interactions should be investigated to predict the risk of AML.

Glutathione S-transferase M1 and T1 genes and susceptibility to chronic myeloid leukemia: a meta-analysis

Variants of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) genes have been implicated as risk factors for chronic myeloid leukemia (CML). However, the genetic association studies that examined the relation between the null genotypes of GSTM1 and GSTT1 genes and risk of developing CML gave conflicting or inconclusive results. In an attempt to interpret these results, a meta-analysis of all available studies (nine studies, with 757 cases and 1959 controls) was performed. In the meta-analysis the pooled odds ratios (OR) were estimated using random effects models. The heterogeneity between studies, the sources of potential bias, and the consistency of genetic effects across ethnicities were explored. Cumulative meta-analysis was also performed. Overall, the meta-analysis showed nonsignificant association between GSTM1 null genotype and CML (OR = 1.00 [0.83-1.20]) and lack of heterogeneity between the studies (p(Q) = 0.87). The association was also nonsignificant in Whites, East Asians, and Indians: OR = 1.38 (0.43-4.46), 0.94 (0.65-1.35), and 1.16 (0.74-1.82), respectively. However, GSTT1 null genotype was associated with increased risk of CML (OR = 1.57 [1.13-2.17]) and the heterogeneity between studies was significant (p(Q) = 0.04). In Indians, the association was significant (OR = 2.89 [1.56-5.35]) whereas in East Asians it was not significant (OR = 1.07 [0.74-1.54]). The combined GSTM1 normal/GSTT1 null genotypes produced significant association (OR = 1.95 [1.17-3.24]). Cumulative meta-analysis for GSTT1 gene showed an upward trend in risk effect, whereas the trend was downward in GSTM1. There was a differential magnitude of effect in large versus small studies. In conclusion, the accumulated evidence indicated an association between GSTT1 null genotype and CML.

Genetic polymorphism of CYP3A5 in Indian chronic myeloid leukemia patients

CYP3A5 is an important genetic contributor to inter-individual differences in CYP3A-dependent clinically important drugs of metabolism and also of various endogenous compounds and environmental contaminants. The CYP3A5*3 allele results in a truncated protein with loss of CYP3A5 expression and CYP3A5*6 is associated with lower CYP3A5 catalytic activity. The polymorphism analysis was performed by PCR-RFLP and some representative cases by direct sequencing. Our case control study involved 183 consecutive North Indian CML patients in chronic phase of disease and 208 geographically and racially matched healthy controls. PCR-RFLP was carried out to determine the frequency of CYP3A5*3 and CYP3A5*6 genotypes. The relationship between these allelic variants and risk of CML was assessed by means of odds ratio (OR) with 95% confidence limits calculated by logistic regression. The frequencies of CYP3A5*1/*1, CYP3A5*1/*3, and CYP3A5*3/*3 genotypes in CML and controls were examined, and the quantitative comparison of the frequency distributions between CML versus control were performed, showing no significant differences among these comparison pairs (P = 0.88, 0.65, and 0.80, respectively). However, we did not find the CYP3A5*6 allele in any of the controls and leukemia patients. It is concluded that there is no association of this polymorphism with the risk of chronic myeloid leukemia.

Evaluating glutathione S-transferase (GST) null genotypes (GSTT1 and GSTM1) as a potential biomarker of predisposition for developing leukopenia

Glutathione S-transferase (GST) enzymes protect cells against xenobiotics and oxidative stress products through an electrophilic conjugation process. We investigated the theta (GSTT1) and mu (GSTM1) null genotypes in a group of leukopenic subjects and normal subjects from Northeast Brazil, evaluating their use as biomarkers of susceptibility for developing leukopenia. In a sample-based case-control study, we analysed white blood cell (WBC) counts and GSTT1 and GSTM1 genotypes. A total of 278 subjects were analysed: 91 with leukopenia and 187 controls. GSTT1 null genotype conferred a 5.92-fold risk for occurrence of leukopenia [odds ratios (OR) = 5.92, CI(MLE): 1.64-26.72, P(MLE) = 0.002] and a 3.90-fold risk of neutropenia (OR = 3.90; CI(MLE): 1.05-13.66; P(MLE) = 0.02), while GSTM1 null genotype conferred a 1.78-fold risk for leukopenia (OR = 1.75; CI(MLE): 1.04-3.06, P(MLE) = 0.017) and no risk of neutropenia (OR = 1.71; CI(MLE): 0.88-3.35; P(MLE) = 0.06). The GSTT1, but not the GSTM1 null genotype, was found to be associated with leukopenia and neutropenia. More cellular and molecular studies are needed to evaluate the existence of genotype interactions, and to confirm the appropriateness of using the GSTT1 and/or GSTM1 null genotypes as biomarkers of susceptibility to white blood-cell deficiencies.

Association of cytochrome P450, glutathione S-transferase and N-acetyl transferase 2 gene polymorphisms with incidence of acute myeloid leukemia

The objective of the paper was to study the association of polymorphisms of phases I and II xenobiotic metabolizing enzyme genes cytochrome P450 (CYP-4501A1*2A, *2B, *2C and *4 alleles, CYP-4502D6*4 allele), glutathione-S-transferase (GSTM1 and GSTT1 null genotypes) and N-acetyl transferase 2 (NAT2*6B and *7A alleles) with the incidence of acute myeloid leukemia (AML) in an eastern Indian population. Polymerase chain reaction and restriction fragment length polymorphism of genomic DNA from peripheral blood cells were used to detect CYP-450 and NAT2 gene polymorphisms in 110 AML patients and 144 racially and geographically matched normal controls. Polymerase chain reaction was also applied to detect GST gene polymorphisms in both groups. A statistically significant difference between the AML group and the normal group was observed in the case of glutathione-S-transferase M1 null (odds ratio 3.25, 95% confidence interval 1.9-5.58, P<0.001) and N-acetyl transferase 2*6B (odds ratio 3.04, 95% confidence interval 1.79-5.16, P<0.001) genotypes. Combined deficiency of N-acetyl transferase 2 and glutathione-S-transferase M1 genes produced an odds ratio of 11.91 (95% confidence interval 4.06-34.96, P<0.001). The effect of N-acetyl transferase 2*6B (P<0.001) is significant only at ages <or=40. In the population studied, persons with glutathione-S-transferase M1 null genotype and N-acetyl transferase 2*6B allele are at increased risk of developing AML, and the risk is considerably enhanced in persons with both glutathione-S-transferase M1 and N-acetyl transferase 2 deficiency.

Increased frequencies of glutathione-S-transferase (GSTM1 and GSTT1) null genotypes in Indian patients with chronic myeloid leukemia

Inherited differences in the capacity of xenobiotic metabolizing enzymes might be an important factor in genetic susceptibility to cancer. Null genotypes of glutathione-S-transferases (GSTs) exhibit absence of enzymatic activity and are hypothesized to be at increased risk of developing cancers. The aim of the study was to examine whether null genotypes of GSTM1 and GSTT1 confer susceptibility to chronic myeloid leukemia (CML). We carried a case control study involving 80 consecutive North Indian CML patients (58 males, 22 females; age (mean+/-S.D.) 36.2+/-10.9 years) and 105 healthy individuals (59 males, 46 females; age (mean+/-S.D.) 36.8+/-11.3 years). Multiplex PCR was carried out to determine the frequency of GSTM1 and GSTT1 null genotypes. The relationship between GSTM1, GSTT1 genotypes and risk of CML was assessed by means of odds ratio (OR) with 95% confidence limits calculated by logistic regression. A test for trend (P(trend)) in increasing the risk of CML having more than one putative high-risk allele or genotype was evaluated by means of the chi-square test. There was no difference in the frequencies of the GSTM1 null genotype and the combined GSTM1 and GSTT1 null genotypes between patients and controls in the study. However, statistical significance was found with GSTT1 null genotype frequency in CML patients as compared to controls (16/80 (20%) versus 9/105 (8.5%); OR=2.67, 95% CI: 1.03-7.01). It projects a 2.67-fold increased risk for CML in individuals with GSTT1 null genotype as compared to those possessing both alleles of the gene. Our findings suggest that heritable GST status may influence the risk of developing CML.

Glutathione-S-transferase M1 polymorphisms on the susceptibility to esophageal cancer among three Chinese minorities: Kazakh, Tajik and Uygur

AIM: To investigate the glutathione-S-transferase M1 (GSTM1) polymorphisms in three Chinese minorities, Kazakh, Uygur, and Tajik; and the pathological significance of GSTM1 polymorphisms in esophageal carcinogenesis in Kazakh.

METHODS: A total of 1121 blood samples (442 males and 679 females) were obtained from healthy Kazakh (654), Uygur (412) and Tajik (55). Primary esophageal squamous cell cancer (ESCC) tissues from Kazakh were obtained from 116 patients who underwent surgery. GSTM1 polymorphisms were analyzed by a combined approach of PCR and electrophoresis techniques.

RESULTS: GSTM1 null genotype was found in 62.63% Uygur, 50.91% Tajik and 47.40% Kazakh. A significantly higher frequency of GSTM1 null genotype in Uygur was observed compared with Kazakh (OR: 1.859, 95% CI: 1.445 -2.391, χ² = 23.71, P = 0.000). In addition, GSTM1 null genotype was found in 23.53% of well-differentiated ESCC in Kazakh, in 49.23% of poorly differentiated ESCC, with a significant difference (OR: 3.152, 95% CI: 1.403-7.080, χ² = 8.018, P = 0.007).

CONCLUSION: There is a marked difference in the frequency of common GSTM1 null genotype between Uygur and Kazakh. GSTM1 null genotype is associated with differentiation of ESCC in Kazakh.

Molecular profiling of chronic myeloid leukemia in eastern India

Molecular breakpoint of the BCR-ABL fusion gene has been characterized for 122 chronic myeloid leukemia patients. Out of 122 cases, 33 b2a2, 69 b3a2, 2 e1a2, and 2 e19a2 cases have been detected. Six coexpressed both b2a2 and b3a2 transcripts. All the coexpressing samples had an A>G polymorphism at the putative splice branchpoint in intron 13. The T>C polymorphism in exon 13, reported to be linked to coexpression, was not present in all the coexpressing patients. No correlation of transcript type with platelet count was detected. Those expressing b2a2 transcript were diagnosed at relatively younger age and with higher white blood cell count, in agreement with other reports. However, the correlation was not statistically significant.

Glutathione S-transferase polymorphisms: cancer incidence and therapy

The super family of glutathione S-transferases (GSTs) is composed of multiple isozymes with significant evidence of functional polymorphic variation. Over the last three decades, data from cancer studies have linked aberrant expression of GST isozymes with the development and expression of resistance to a variety of chemicals, including cancer drugs. This review addresses how differences in the human GST isozyme expression patterns influence cancer susceptibility, prognosis and treatment. In addition to the well-characterized catalytic activity, recent evidence has shown that certain GST isozymes can regulate mitogen-activated protein kinases or can facilitate the addition of glutathione to cysteine residues in target proteins (S-glutathionylation). These multiple functionalities have contributed to the recent efforts to target GSTs with novel small molecule therapeutics. Presently, at least two drugs are in late-stage clinical testing. The evolving functions of GST and their divergent expression patterns in individuals make them an attractive target for drug discovery.

Rapid determination of common mutations in glutathione S-transferase gene by PCR-based methods in healthy Chinese

BACKGROUND

The glutathione S-transferase (GST) superfamily comprises multiple isozymes with compelling evidence of functional polymorphisms in various ethnic groups. All these mutations, in particular those in class mu, pi and theta GST, are likely to contribute to interindividual differences in responses to xenobiotics including response to chemotherapy and associated with altered disease. The frequency of common GST mutations in Uygur Chinese is unknown. We investigated the common mutations of GSTM1, GSTT1, and GSTP1 in Uygur (N=154) Chinese and compare with Han Chinese (N=196).

METHOD

GSTM1 and GSTT1 polymorphisms were analyzed by multiplexed PCR, and GSTP1 polymorphism was detected by PCR-based restriction fragment length polymorphism (RFLP) analysis.

RESULTS

GSTM1 null genotype was found in 53.2% Uygur Chinese, which was close to that in Han Chinese (56.1%) (P=0.592). A significantly lower frequency (P<0.05) of GSTT1 null genotype in Uygur Chinese (26.6%) was observed compared with Han Chinese (50.0%). Uygur Chinese exhibited a GSTP1 genotype distribution of 51.3% I/I, 40.2% I/V and 8.4% V/V, which was different from that in Han Chinese (60.7% I/I, 35.2% I/V and 4.1% V/V).

CONCLUSIONS

There is marked ethnic difference in the frequency of common GSTT1 and GSTP1 mutation, but not GSTM1 mutation, between Uygur and Han Chinese.