Human glutathione S-transferase P1 polymorphisms: relationship to lung tissue enzyme activity and population frequency distribution

Methylenetetrahydrofolate reductase C677T and glutathione S-transferase P1 A313G are associated with a reduced risk of preeclampsia in Maya-Mestizo women

Preeclampsia, a common complication of pregnancy, is characterized by elevated blood pressure and proteinuria developing after 20 weeks' gestational age. Susceptibility to this syndrome is believed to have a genetic component. The aim of this study was to investigate whether or not the 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T and glutathione S-transferase P1 (GSTP1) A313G polymorphisms are associated with preeclampsia in Maya-Mestizo women. A case-control study was performed, in which 125 preeclamptic patients and 274 healthy controls were genotyped for the MTHFR C677T and GSTP1 A313G polymorphisms by real-time PCR allelic discrimination. Allele and genotype frequencies were compared using the chi2 tests. The MTHFR 677T allele and the 677TT genotype were significantly more frequent in the controls, suggesting an association with a decreased risk of preeclampsia (p = 0.017 and p = 0.007, respectively). Similarly, GSTP1 313GG/GC genotypes and the G allele were more frequent in controls, showing a significant association with reduced risk of preeclampsia (p = 0.008 and p = 0.013, respectively). Our results suggest, for the first time, that the MTHFR 677T and GSTP1 313G polymorphisms confer a significantly decreased risk of developing preeclampsia in the Mexican Maya-Mestizo population.

GSTP1 Ile105Val polymorphism correlates with progression-free survival in MCRC patients treated with or without irinotecan: a study of the Dutch Colorectal Cancer Group

A Valine residue at position 105 of the GSTP1 protein results in decreased enzyme activity. As nuclear GSTP1 activity decreases irinotecan cytotoxicity, Val-allele carriers may benefit more from irinotecan chemotherapy. Our aim was to investigate the association of GSTP1 genotype with treatment outcome of irinotecan. Progression-free survival (PFS) and toxicity were determined in 267 metastatic colorectal cancer (MCRC) patients who were treated with first-line capecitabine (CAP) plus irinotecan (CAPIRI), or CAP single agent in a prospective randomised phase III trial (CAIRO). GSTP1 genotype was determined by Pyrosequencing. Patients receiving CAP showed a PFS of 6.6 (Ile/Ile), 6.0 (Ile/Val) and 6.5 months (Val/Val); compared to 7.0 (Ile/Ile), 8.8 (Ile/Val) and 9.2 months (Val/Val) with CAPIRI. Median PFS was 2.7 months longer in Val-allele carriers treated with CAPIRI compared to CAP (P=0.005). Patients with the Ile/Ile genotype showed similar PFS with CAPIRI and CAP (7.0 compared to 6.6 months, P=0.972). Toxicity did not differ significantly among genotypes. GSTP1 codon 105 polymorphism may be predictive for the response to irinotecan-based chemotherapy in patients with MCRC, with the Val-allele being associated with a better outcome. Ile/Ile genotype patients do not appear to benefit from the addition of irinotecan to CAP.

Pharmacogenetic prediction of clinical outcome in advanced colorectal cancer patients receiving oxaliplatin/5-fluorouracil as first-line chemotherapy

To determine whether molecular parameters could be partly responsible for resistance or sensitivity to oxaliplatin (OX)-based chemotherapy used as first-line treatment in advanced colorectal cancer (CRC). We studied the usefulness of the excision repair cross-complementing 1 (ERCC1), xeroderma pigmentosum group D (XPD), XRCC1 and GSTP1 polymorphisms as predictors of clinical outcome in these patients. We treated 126 CRC patients with a first-line OX/5-fluorouracil chemotherapeutic regimen. Genetic polymorphisms were determined by real-time PCR on an ABI PRISM 7000, using DNA from peripheral blood. Clinical response (CR), progression-free survival (PFS) and overall survival (OS) were evaluated according to each genotype. In the univariate analysis for CR, ERCC1-118 and XPD 751 polymorphisms were significant (P=0.02 and P=0.05, respectively). After adjustment for the most relevant clinical variables, only ERCC1-118 retained significance (P=0.008). In the univariate analysis for PFS, ERCC1-118 and XPD 751 were significant (P=0.003 and P=0.009, respectively). In the multivariant analysis, only the XPD 751 was significant for PFS (P=0.02). Finally, ERCC1-118 and XPD 751 polymorphisms were significant in the univariate analysis for OS (P=0.006 and P=0.015, respectively). Both genetic variables remained significant in the multivariate Cox survival analysis (P=0.022 and P=0.03). Our data support the hypothesis that enhanced DNA repair diminishes the benefit of platinum-based treatments.

Functional significance of the GAG trinucleotide-repeat polymorphism in the gene for the catalytic subunit of gamma-glutamylcysteine ligase

Gamma-glutamylcysteine ligase (GCL) is the rate-limiting enzyme in glutathione (GSH) synthesis. A GAG-repeat polymorphism in the 5' UTR of the gene coding for the catalytic subunit of GCL (GCLC) has been associated with altered GSH levels in vitro. Thus, we hypothesized that this polymorphism is associated with altered GCL activity and blood GSH levels in vivo. A total of 256 healthy United States black and white adults were genotyped for the GAG polymorphism and blood GSH levels were measured. In a subset of 107 individuals, blood GCL activity was determined. Five alleles with 4, 7, 8, 9, and 10 GAG repeats were observed. The most prevalent genotype was 7/9 (40%) followed by 7/7 (32%) and 9/9 (11%). GSH levels were 15% lower in 9/9 individuals than 7/9 individuals (P=0.05). GCL activity was 21% lower in 9/9 individuals than 7/7 individuals (P=0.04). A decreasing trend of GCL activity was observed in the order of 7/7>7/9>9/9 (P=0.04). These findings show that 9/9 individuals have lower blood GSH levels, which is likely due to a decrease in GCL activity. Such individuals might be more susceptible to oxidative stress-related diseases than individuals with other genotypes.

Glutathione s-transferase p1: gene sequence variation and functional genomic studies

Glutathione S-transferase P1 (GSTP1) is of importance for cancer research because of its role in detoxifying carcinogens, activating antineoplastic prodrugs, metabolizing chemotherapeutic agents, and its involvement in cell cycle and apoptosis regulation. Two common GSTP1 genetic polymorphisms have been studied extensively. However, the full range of GSTP1 genetic variation has not been systematically characterized in the absence of disease pathology. We set out to identify common GSTP1 polymorphisms in four ethnic groups, followed by functional genomic studies. All exons, splice junctions, and the 5'-flanking region of GSTP1 were resequenced using 60 DNA samples each from four ethnic groups. The 35 single-nucleotide polymorphisms (SNP) identified included six nonsynonymous SNPs and 17 previously unreported polymorphisms. GSTP1 variant allozymes were then expressed in COS-1 cells, and five displayed significantly altered levels of enzyme activity. One decreased to 22% of the wild-type (WT) activity. Four variant allozymes had K(m) values that differed significantly from that of the WT, and five showed altered levels of immunoreactive protein compared with WT, with a significant correlation (r = 0.79, P < 0.007) between levels of immunoreactive protein and enzyme activity in these samples. In the Mexican American population, five linked SNPs were significantly associated with GSTP1 mRNA expression, one of which was found by electrophoretic mobility shift assay to alter protein binding. These studies have identified functionally significant genetic variation, in addition to the two frequently studied GSTP1 nonsynonymous SNPs, that may influence GSTP1's contribution to carcinogen and drug metabolism, and possibly disease pathogenesis and/or drug response.

Interactions between glutathione S-transferase P1, tumor necrosis factor, and traffic-related air pollution for development of childhood allergic disease

BACKGROUND

Air pollutants may induce airway inflammation and sensitization due to generation of reactive oxygen species. The genetic background to these mechanisms could be important effect modifiers.

OBJECTIVE

Our goal was to assess interactions between exposure to air pollution and single nucleotide polymorphisms (SNPs) in the beta2-adrenergic receptor (ADRB2), glutathione S-transferase P1 (GSTP1), and tumor necrosis factor (TNF) genes for development of childhood allergic disease.

METHODS

In a birth cohort originally of 4,089 children, we assessed air pollution from local traffic using nitrogen oxides (traffic NO(x)) as an indicator based on emission databases and dispersion modeling and estimated individual exposure through geocoding of home addresses. We measured peak expiratory flow rates and specific IgE for inhalant and food allergens at 4 years of age, and selected children with asthma symptoms up to 4 years of age (n = 542) and controls (n = 542) for genotyping.

RESULTS

Interaction effects on allergic sensitization were indicated between several GSTP1 SNPs and traffic NO(x) exposure during the first year of life (p(nominal) < 0.001-0.06). Children with Ile105Val/Val105Val genotypes were at increased risk of sensitization to any allergen when exposed to elevated levels of traffic NO(x) (for a difference between the 5th and 95th percentile of exposure: odds ratio = 2.4; 95% confidence interval, 1.0-5.3). In children with TNF-308 GA/AA genotypes, the GSTP1-NO(x) interaction effect was even more pronounced. We observed no conclusive interaction effects for ADRB2.

CONCLUSION

The effect of air pollution from traffic on childhood allergy appears to be modified by GSTP1 and TNF variants, supporting a role of genes controlling the antioxidative system and inflammatory response in allergy.

[Pharmacogenetics in oncology]

Pharmacogenetics studies the relationship between genetic polymorphisms and individual responses to drugs. In recent years, there has been a great progress in our knowledge of the effects of drug-metabolizing enzymes and molecular target genetic polymorfisms on cancer chemotherapy. Pharmacogenetics focuses on the prediction of drug efficacy and toxicity based on a patient's genetic profile with routinely applicable genetic tests to select the most appropriate medication at optimal doses for each individual patient. Two years ago the FDA approved one genetic test to detect patients with increased risk of severe toxicity associated with irinotecan therapy. There have also been commercialized genetic chips to genotyping two cytochrome P450 enzymes at the same time. Prospectively, stratifying patients based on genotype may identify subpopulations likely to experience severe toxicity or to derive benefit from a particular treatment strategy, helping us move toward the ultimate goal of individualized therapy. In this review, we describe the clinical effects of polymorphisms that may influence cancer chemotherapy.

Effects of Genetic Polymorphisms of Glutathione S-transferase P1 on Helicobacter pylori-associated Gastric Cancer

BACKGROUND/AIMS

Glutathione S-transferase P1 (GSTP1) scavenges radicals via its peroxidase activity. The purpose of this study was to determine the association of GSTP1 genetic polymorphisms with the expression of H. pylori-associated gastroduodenal disease.

METHODS

This study involved 1,911 subjects, comprising patients with four diseases (gastric cancer, dysplasia, benign gastric ulcer, and duodenal ulcer disease) and controls. Biallelic polymorphisms were genotyped by restriction fragment length polymorphism techniques.

RESULTS

The frequency of the genetic polymorphism at nucleotide 313 of GSTP1 did not differ among the five study groups. However, when the gastric cancer group was subdivided into advanced gastric cancer (AGC) and early gastric cancer, the frequency of the G/G genotype was significantly higher in the AGC group than in all the control subgroups (OR: 1.2, 95% CI: 1.1-4.9). The frequency of this genotype differed significantly in the H. pylori-positive AGC group (OR: 2.7, 95% CI: 1.1-6.3) but not in the H. pylori-negative group. Furthermore, the difference was greater in the intestinal type, and was not found in diffuse types of disease.

CONCLUSIONS

This study found that genetic polymorphisms of GSTP1 were associated with H. pylori-associated gastric cancer only during the advanced stage of gastric cancer, with intestinal-type histology evident in H. pylori-positive subjects.

Management of colorectal cancer: a role for genetics in prevention and treatment?

Colorectal cancer remains one of the most common cancers in the Western world and amongst the top three causes of cancer morbidity and death. Cancer is caused by genetic mutations, but currently there is little use of genetic information in the clinic with the exception of establishing germline mutations for the uncommon predisposing syndromes. Rapid advances in technologies allowing high throughput analysis of germline and somatic mutations raises the possibility that genetics will find a major role in the clinic distinguishing individuals at low to high risk of cancer, allowing early intervention and stratification of cancers based on mutational pathways for therapeutic interventions. In the future, this will lead to treatment regimes tailored to the individuals and their tumor. Here, we summarize the genetics underlying colorectal cancer and the future role of genetics in prevention, diagnosis, classification and treatment.

Identifying genetic variants that contribute to chemotherapy-induced cytotoxicity

Patients treated with anticancer chemotherapy exhibit variation, both in terms of tumor response and the incidence and severity of adverse effects. The etiology of this variation is multifactorial with genetic factors likely contributing to a significant extent. Pharmacogenetic and genomic studies can be used to identify the genetic variants that contribute to interindividual variation in susceptibility to chemotherapy-induced cytotoxicity. This review will describe candidate and whole-genome approaches, describe the advantages and disadvantages of each, and illustrate how they can be used to obtain clinically relevant information. Specific emphasis is given to recent advances emerging from the International HapMap Project and to the development of genetic signatures, as opposed to expression signatures, to explain drug sensitivity and resistance.

Genetic polymorphisms of human cytosol glutathione S-transferases and prostate cancer

Glutathione S-transferases (GSTs) are involved in the metabolism of a wide range of carcinogenic chemicals. In humans, cytosol GSTs are divided into eight classes: alpha (GSTA), mu (GSTM), pi (GSTP), theta (GSTT), tau (GSTZ), sigma (GSTS), omicron (GSTO) and kappa (GSTK). The allelic polymorphism of these enzymes is associated with variations in enzyme activity; hence, it may affect the concentration of activated carcinogenic chemicals in the body. In addition to the metabolism of chemical carcinogens, GSTs metabolize steroid hormones, compounds in the diet and other agents potentially involved in prostate carcinogenesis. Three genetic polymorphisms of GSTs, GSTM1*0 (null), GSTT1*0 (null) and GSTP1 A313G, have been well documented. No consistent associations between GSTM1, GSTT1 or GSTP1 genotypes and prostate cancer have been observed. Recent meta-analysis reports show that these polymorphisms of GSTM1, GSTT1 and GSTP1 are unlikely to be major determinants of susceptibility to prostate cancer.

Association between GSTP1 gene polymorphism and serum α-GST concentrations undergoing sevoflurane anaesthesia

BACKGROUND AND OBJECTIVES

The measurement of alpha-glutathione-S-transferase enzyme is one of the most sensitive indicators of hepatocellular function. Variation in the glutathione-S-transferase P1 gene clusters has been intensively investigated and polymorphism has been described. The aim of the study was to assess whether an association exists between glutathione-S-transferase P1 gene polymorphism and serum alpha-glutathione-S-transferase concentrations for the first postoperative day in patients who underwent anaesthesia with sevoflurane.

METHODS

In all, 54 unrelated patients were enrolled in this study. Anaesthesia was induced with thiopental and fentanyl. Vecuronium was used for neuromuscular relaxation before endotracheal intubation. Anaesthesia was maintained with sevoflurane in a gas mixture containing 50% nitrous oxide in oxygen. Peripheral venous blood samples to determine serum alpha-glutathione-S-transferase concentrations were collected before induction (T1), at the end of anaesthesia (T2) and at 24-h postoperatively (T3). Enzyme-linked immunosorbent assay (ELISA) immunoassay was used to measure alpha-glutathione-S-transferase levels. Genomic DNA was isolated from serum samples using a genomic DNA purification kit. In order to detect the variants of glutathione-S-transferase P1, polymerase chain reaction-restriction fragment length polymorphism analysis was employed.

RESULTS

Early postoperative serum alpha-glutathione-S-transferase levels for all patients were significantly increased when compared with preanaesthetic and 24-h postoperatively (P 0.05).

CONCLUSIONS

Although alpha-glutathione-S-transferase levels were elevated in all patients after sevoflurane anaesthesia, levels remained high at 24 h in patients with glutathione-S-transferase P1 Ile105Val genotypes compared to controls.

Review on genetic variants and maternal smoking in the etiology of oral clefts and other birth defects

A spectrum of adverse pregnancy outcomes, including preterm birth, low birth weight, and birth defects has been linked with maternal smoking during pregnancy. This article includes a review of studies investigating interactions between genetic variants and maternal smoking in contributing to birth defects using oral clefting as a model birth defect. The primary gene-smoking studies for other major birth defects are also summarized. Gene-environment interaction studies for birth defects are still at an early stage with several mixed results, but evolving research findings have begun to document clinically and developmentally important interactions. As samples and data become increasingly available, more effort is needed in designing innovative analytical methods to study gene-environment interactions.

A protective effect of glutathione-S-transferase GSTP1*Val(105) against polymorphic light eruption

Polymorphic light eruption (PLE) is a common skin disease, susceptibility to which is genetically determined. The prevalence of PLE is significantly increased in patients with lupus erythematosus (LE) including subacute cutaneous lupus erythematosus (SCLE) and discoid lupus erythematosus (DLE), which may reflect a common genetic background. Experimental evidence supports a role for reactive oxygen species (ROS) in the pathogenesis of PLE, and the family of glutathione-S-transferase (GST) enzymes exerts a critical physiological role in cellular protection against this oxidative damage. Our aim was to look for association between the functional GST gene polymorphisms and PLE, SCLE, and DLE in a case-control study. The carrier frequency of GSTP1 Val(105) in subjects with PLE was 40%, significantly lower than the carrier frequency in controls (54%, P=0.019), although significance was lost on correction for multiple testing. However, the carrier frequency of the GSTP1 Val(105) allele in combined cutaneous LE (SCLE and DLE) patients with PLE was 42%, significantly lower than in those without PLE (72%), which did survive correction (corrected P=0.043). We have identified evidence supporting a protective GSTP1 allele, the first genetic association to be reported for PLE. This supports a role for ROS in the pathogenesis of PLE and may provide a therapeutic target for future treatment of this common, often disabling, condition.

The influence of genetic polymorphisms of GSTP1 on the development of asbestosis

OBJECTIVE

Genetic factors play an important role in the development of asbestosis. The aim of this study was to investigate whether genetic polymorphisms of glutathione S-transferase (GST) P1 represent a risk factor for this disease.

METHODS

The study population included 262 workers with asbestosis and 265 matched controls. Information on cumulative asbestos exposure was available. A real-time PCR based on the 5' nuclease assay was designed for the analysis of GSTP1 Ile105Val and Ala114Val polymorphisms.

RESULTS

Asbestosis was associated with GSTP1 genotype coding for an enzyme with high conjugation capacity versus genotypes resulting in intermediate and low enzyme activity (odds ratio = 1.49, confidence interval = 1.06-2.10).

CONCLUSIONS

The key finding of the study was that GSTP1 genotype coding for an enzyme with high conjugation capacity significantly increases the risk of developing asbestosis.

The I,105V polymorphism in glutathione S-transferase P1, parental smoking and the risk for nonsyndromic cleft lip with or without cleft palate

Genetic variations in the detoxification enzyme glutathione S-transferase P1 (GSTP1) may modify the teratogenicity of lifestyles, such as smoking. We investigated the role of the I105V polymorphism in GSTP1, parental periconception smoking, and their interaction with nonsyndromic cleft lip with or without cleft palate (CL/P) risk in the offspring. The GSTP1 I105V polymorphisms were determined in Dutch non-consanguineous Caucasians comprising of 155 CL/P triads (mother, father, child) and 195 control triads. The analyses were also carried out on complete triads only (n=69 CL/P and n=95 controls). Transmission disequilibrium testing and logistic regression analyses were performed. Neither maternal nor paternal smoking increased CL/P risk; odds ratios (OR): 1.2, 95 confidence intervals (CI)=0.7-2.0 and OR: 1.0, 95% CI=0.6-1.6, respectively. Carriership of the polymorphic Val105 allele in mothers may increase CL/P risk, OR: 1.5, 95% CI=0.96-2.5. Children homozygous for the Val105 allele may show an increased risk of CL/P, OR: 2.2, 95% CI=0.8-6.4. Maternal smoking tended to increase CL/P risk in mothers and children carrying Val105 alleles, OR=1.9, 95% CI=0.9-4.0 and OR=2.2, 95% CI=0.98-4.9, respectively. The highest risk for CL/P in children carrying Val105 alleles with a smoking father was 1.7, 95% CI=0.8-3.5. The GSTP1 I105V polymorphism in mothers and/or children either alone or in combination with maternal smoking may contribute to CL/P risk. Although of borderline significance, these results may underline the importance of smoking cessation in the periconception period for the prevention of CL/P in future generations.

Detoxification enzyme polymorphisms are not involved in duodenal adenomatosis in familial adenomatous polyposis

Background

Patients with familial adenomatous polyposis (FAP) are at high risk of developing duodenal adenomas and carcinomas. Besides germline mutations in the adenomatous polyposis coli (APC) gene, additional factors may influence the age of onset and number of duodenal adenomas. This study compared the genotype distributions of duodenal detoxification enzyme isoforms in patients with FAP and controls.

Methods

The study included 85 patients with FAP and 218 healthy age- and sex-matched controls. Genotyping of all participants using polymerase chain reaction was performed to detect polymorphisms in isoforms of uridine 5′-diphosphate glucuronosyltransferases (UGTs) and glutathione S-transferases (GSTs): UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A10, UGT2B4, UGT2B7, UGT2B15, GSTA1, GSTP1, GSTM1 and GSTT1.

Results

The variant genotypes of UGT1A3 were less common in patients with FAP than in controls (odds ratio 0·39 (95 per cent confidence interval 0·22 to 0·67)). There were no associations between FAP and the other polymorphic genes. The polymorphisms investigated had no predictive value for the severity of duodenal adenomatosis in patients with FAP.

Conclusion

Although the variant genotypes of UGT1A3 were less common in patients with FAP than in those without, this did not modulate the severity of duodenal adenomatosis.

Pharmacogenomics in colorectal cancer: The first step for individualized-therapy

Interindividual differences in the toxicity and response to anticancer therapies are currently observed in practically all available treatment regimens. A goal of cancer therapy is to predict patient response and toxicity to drugs in order to facilitate the individualization of patient treatment. Identification of subgroups of patients that differ in their prognosis and response to treatment could help to identify the best available drug therapy according the genetic profile. Several mechanisms have been suggested to contribute to chemo-therapeutic drug resistance: amplification or overexpression of membrane transporters, changes in cellular proteins involved in detoxification or in DNA repair, apoptosis and activation of oncogenes or tumor suppressor genes. Colorectal cancer (CRC) is regarded as intrinsically resistant to chemotherapy. Several molecular markers predictive of CRC therapy have been included during the last decade but their results in different studies complicate their application in practical clinical. The simultaneous testing of multiple markers predictive of response could help to identify more accurately the true role of these polymorphisms in CRC therapy. This review analyzes the role of genetic variants in genes involved in the action mechanisms of the drugs used at present in colorectal cancer.

[Childhood leukemia: a genetic disease!]

Cancer affects 1 in every 500 children before the age of 14. Little is known about the etiology of this heterogeneous group of diseases despite the fact that they constitute the major cause of death by disease among this population. Because of its relatively higher prevalence, most of the work done in pediatric oncogenetics has been focused on leukemias, particularly acute lymphoblastic leukemia (ALL). Although it is now well accepted that genetic variations play a significant role in determining individual's cancer susceptibility, few studies have explored genetic susceptibility to childhood leukemia with respect to polymorphisms. The main biological mechanisms contributing to cancer susceptibility can be grouped into broad categories : (1) cellular growth and differentiation, (2) DNA replication and repair, (3) xenobiotic metabolism, (4) apoptosis, (5) oxidative stress response and (6) cell cycle. To evaluate whether candidate genes in these pathways are involved in childhood leukemogenesis, we conducted association studies. We showed that leukemogenesis in children may be associated with genetic variants and that the combination of genotypes seems to be more predictive of risk than either of them independently. These results indicate that the genetic investigation of several enzymes (or metabolic pathways) is needed to explain the physiopathology of childhood leukemia because of the complexity of the environment and that of the inter-individual variability in cancer susceptibility.

Genetic polymorphisms and micronucleus formation: a review of the literature

The formation of micronuclei (MN) is extensively used in molecular epidemiology as a biomarker of chromosomal damage, genome instability, and eventually of cancer risk. The occurrence of MN represents an integrated response to chromosome-instability phenotypes and altered cellular viabilities caused by genetic defects and/or exogenous exposures to genotoxic agents. The present article reviews human population studies addressing the relationship between genetic polymorphisms and MN formation, and provides insight into how genetic variants could modulate the effect of environmental exposures to genotoxic agents, host factors (gender, age), lifestyle characteristics (smoking, alcohol, folate), and diseases (coronary artery disease, cancer). Seventy-two studies measuring MN frequency either in peripheral blood lymphocytes or exfoliated cells were retrieved after an extensive search of the MedLine/PubMed database. The effect of genetic polymorphisms on MN formation is complex, influenced to a different extent by several polymorphisms of proteins or enzymes involved in xenobiotic metabolism, DNA repair proteins, and folate-metabolism enzymes. This heterogeneity reflects the presence of multiple external and internal exposures, and the large number of chromosomal alterations eventually resulting in MN formation. Polymorphisms of EPHX, GSTT1, and GSTM1 are of special importance in modulating the frequency of chromosomal damage in individuals exposed to genotoxic agents and in unexposed populations. Variants of ALDH2 genes are consistently associated with MN formation induced by alcohol drinking. Carriers of BRCA1 and BRCA2 mutations (with or without breast cancer) show enhanced sensitivity to clastogens. Some evidence further suggests that DNA repair (XRCC1 and XRCC3) and folate-metabolism genes (MTHFR) also influence MN formation. As some of the findings are based on relatively small numbers of subjects, larger scale studies are required that include scoring of additional endpoints (e.g., MN in combination with fluorescent in situ hybridization, analysis of nucleoplasmic bridges and nuclear buds), and address gene-gene interactions.

Antioxidant defense markers modulated by glutathione S-transferase genetic polymorphism: results of lung cancer case-control study

Oxidative stress and xenobiotic metabolizing enzymes are suspected to be related to carcinogenesis by different cellular mechanisms. Hence, our study aimed at identifying potential relationships between antioxidant defense parameters measured in blood and glutathione S-transferase (GST) genetic polymorphisms of four GST izoenzymes in lung cancer patients and reference individuals. The case-control study included 404 lung cancer patients and 410 non-cancer subjects as controls, matched by age, gender and place of living (central Poland). In control subjects with GSTM3*A/*A, GSTT1 null, GSTM1 null + GSTT1 null, GSTM3*A/*A + GSTT1 null genotype, glutathione peroxidase activity was significantly higher (P < 0.05) than in controls possessing respective potential protective GST genotypes. Controls with GSTM3*A/*A + GSTP1*B genotype presented significantly higher ceruloplasmin activity (P < 0.05) than GSTM3*B + GSTP1*A/*A carriers. Zinc level was significantly higher (P < 0.05) in controls and cases with GSTP1*B + GSTT1 null genotype and in cases with GSTM1 null + GSTP1*B genotype, when compared with respective potential protective GST genotypes. This case-control study indicates that particular defective GST genotypes may enhance the defense against oxidative stress. The potential relationship between the investigated antioxidative enzymes and microelements, and common functional genetic polymorphism of GST was observed mostly in control subjects.

Multiplex PCR detection of GSTM1, GSTT1, and GSTP1 gene variants: simultaneously detecting GSTM1 and GSTT1 gene copy number and the allelic status of the GSTP1 Ile105Val genetic variant

The glutathione S-transferase (GST) genes GSTM1, GSTT1, and GSTP1 are involved in the detoxification of a broad range of toxic substances. Genetic polymorphisms in these genes have been studied intensively for their potential role in cancer susceptibility and drug response. In Caucasians, the enzyme activity of GSTM1 and GSTT1 is absent in approximately 50 and 15% of the population, respectively, due to deletions of both chromosomal copies of the genes. A trimodal phenotype pattern exists in which individuals with two, one, or no functional genes are fast, intermediate, or slow "conjugators," respectively. Most studies investigating the effect of the GSTM1 and GSTT1 deletions do not distinguish between fast and intermediate conjugators because the applied genotyping assays only detect if at least one copy of either gene is present. We present a multiplex PCR assay that detects if an individual has none, one, or two copies of the GSTM1 and GSTT1 genes and simultaneously detects the allelic status of the GSTP1 Ile105Val genetic variant. A total of 200 Danes, 100 Somalis, and 100 Greenlanders were genotyped. This multiplex PCR assay enables future large-scale studies to investigate the role of GSTs.

Sulfotransferase 1A1 and glutathione S-transferase P1 genetic polymorphisms modulate the levels of urinary 8-hydroxy-2'-deoxyguanosine in betel quid chewers

Betel quid chewing has been associated with several human cancers. However, the role of betel quid in carcinogenesis remains uncertain. Piper betel contains high concentrations of safrole (an inducer of DNA oxidative damage). Safrole may be metabolized by hepatic sulfotransferase 1A1 (SULT1A1), or glutathione S-transferases (GSTM1, GSTT1, and GSTP1). Thus, we investigated the association of genetic polymorphisms of SULT1A1, GSTM1, GSTT1, and GSTP1 with DNA oxidative damage among betel quid chewers. A biomarker for oxidative stress, urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) level, was analyzed using isotope-dilution LC-MS/MS in 64 betel quid chewers and 129 non-betel quid chewers. Data on demographics and habits (smoking, alcohol drinking, and betel quid chewing) were obtained from questionnaires. Our results revealed that urinary 8-OHdG level was higher in chewers with SULT1A1 Arg-His genotype than in chewers with SULT1A1 Arg-Arg genotype. Urinary 8-OHdG level was also higher in chewers with GSTP1 Ile-Ile genotype. Furthermore, the combined effect of SULT1A1 and GSTP1 genotypes on urinary 8-OHdG was evaluated. Non-chewers with both SULT1A1 Arg-Arg and GSTP1 Val-Val/Ile-Val (reference group) had the lowest mean level (3.6 ng/mg creatinine), whereas chewers with either SULT1A1 Arg-His or GSTP1 Ile-Ile had the highest 8-OHdG mean level (6.2 ng/mg creatinine; vs. reference group, P = 0.04). Chewers with both of SULT1A1 Arg-Arg and GSTP1 Val-Val/Ile-Val (4.6 ng/mg creatinine), and non-chewers with either SULT1A1 Arg-His or GSTP1 Ile-Ile (4.7 ng/mg creatinine) had a moderately increased 8-OHdG level. Thus, the susceptible SULT1A1 and GSTP1 genotypes may modulate increased DNA oxidative stress elicited by betel-quid chewing.

Population pharmacokinetics of melphalan and glutathione S-transferase polymorphisms in relation to side effects

Melphalan is associated with severe side effects such as mucositis, diarrhea, and myelosuppression. We investigated how much the individual severity of these side effects is predicted by pharmacokinetics. In addition, we studied glutathione S-transferase GSTM1, GSTT1, and GSTP1 polymorphisms in relation to adverse events. A high interindividual pharmacokinetic variability was observed in 84 patients. There was a linear correlation between creatinine and melphalan clearance (P=0.0004). Patients treated with a dose > or = 70 mg/m(2) had a 23-fold increased risk to develop mucositis (P<0.001) and a 12-fold increased risk to develop diarrhea (P<0.001) compared with lower doses. The GSTP1 codon 105 polymorphism may be relevant for development of mucositis and the GSTT1 deletion may predict diarrhea, but these findings require confirmation. Melphalan-induced side effects were significantly dependent only on dose. Therapeutic drug monitoring or genotyping for GST does not appear to be very helpful in optimizing therapy with melphalan.

Glutathione S-transferase P1 and T1 gene polymorphisms predict longitudinal course and age at onset of Alzheimer disease

OBJECTIVE

Oxidative stress has been suggested as a contributor of Alzheimer disease (AD) neurodegeneration, particularly in those patients with late-onset AD (LOAD). Therefore, the authors studied the effect of glutathione S-transferase (GST) P1-M1-T1 gene polymorphisms and their interactions with the apolipoprotein E (ApoE) epsilon4 allelic variant on the three-year longitudinal course of AD.

METHODS

Global cognitive level as measured by the Mini-Mental State Exam, basic activities of daily living (BADLs) as measured by the Physical Self-Maintenance Scale, and behavior as measured by the Neuropsychiatric Inventory, were assessed at baseline and after 1, 2, and 3 years in a sample of 99 LOAD patients. These subjects were drug naive and had undergone the first clinical examination for the diagnosis of AD.

RESULTS

A multiple regression analysis indicated that the presence of ApoE epsilon4 allelic variant or GSTT1 null phenotype predicted the faster age at onset of the illness (F = 5.76, df = 2, 96, p = 0.0043). Carriers of GSTP1 *C allelic variant had a faster decline in cognitive functions (repeated measures analysis of variance [ANOVA]: F = 4.00, df = 3, 285, p = 0.008) and in BADLs (repeated measures ANOVA: F = 5.27, df = 3, 285, p = 0.001). This faster decline was independent from ApoE epsilon4 allele possession. No effect of GST P1-M1-T1 polymorphisms was found on behavioral symptom severity.

CONCLUSION

These data are in line with the hypotheses that oxidative damage is a prominent feature in the clinical progression and the age at onset of LOAD.

Ile105Val GSTP1 polymorphism and susceptibility to colorectal carcinoma in Bulgarian population

BACKGROUND AND AIMS

Etiologically, the sporadic colorectal cancer (CRC) is a complex and multifactorial disease that is linked to both exogenic and endogenic factors. Accumulating evidence indicates that susceptibility to cancers, including CRC, is mediated by genetically determined differences in the effectiveness of detoxification of potential carcinogens. A member of the glutathione-S-transferase (GST) family, GSTP1, is an important candidate for involvement in susceptibility to carcinogen-associated CRC. An A-->G transition in exon 5 of the GSTP1 gene resulting in Ile(105)Val amino acid substitution has been identified. This change leads to alteration in catalytic efficiency of variant enzyme. The aim of the current study was to evaluate the influence of Ile(105)Val GSTP1 polymorphism on susceptibility to CRC.

MATERIALS AND METHODS

The GSTP1 genotyping was conducted in a case-control study of 80 ethnic Bulgarian CRC patients and 126 unaffected controls using polymerase chain reaction restriction fragment length polymorphism method.

RESULTS

A statistically significant case-control difference in genotype frequencies was observed: 0.69 vs 0.54 for Ile/Ile, 0.22 vs 0.39 for Ile/Val, and 0.09 vs 0.07 for Val/Val (p = 0.049). The odds ratio (OR) for Val/Val was close to 1 (0.96, 95%CI: 0.35-2.66, p = 0.942), whereas the OR for Ile/Val was significantly lower, 0.45 (95%CI: 0.24-0.86, p = 0.016), compared to the referent Ile/Ile genotype. Although a prevalence of the GSTP1 variant allele-containing genotypes (Ile/Val or Val/Val) was found in controls than in patients (OR = 0.53, 95%CI: 0.30-0.96, p = 0.035), the allele frequencies did not show significant difference between cases and controls (p = 0.127).

CONCLUSIONS

Based on the obtained protective effect of Ile/Val GSTP1 genotype, we could suggest that Ile(105)Val GSTP1 polymorphism may play some role in susceptibility to CRC.

Genetic polymorphism and function of glutathione S-transferases in tumor drug resistance

The human glutathione S-transferase, GSTs, possess both enzymatic and non-enzymatic functions and are involved in many important cellular processes, such as, phase II metabolism, stress response, cell proliferation, apoptosis, oncogenesis, tumor progression and drug resistance. The non-enzymatic functions of GSTs involve their interactions with cellular proteins, such as, JNK, TRAF, ASK, PKC, and TGM2, during which, either the interacting protein partner undergoes functional alteration or the GST protein itself is post-translationally modified and/or functionally altered. The majority of GST genes harbor polymorphisms that influence their transcription and/or function of their encoded proteins. This overview focuses on recent insights into the biology and pharmacogenetics of GSTs as a determinant of cancer drug resistance and response of cancer patients to therapy.

Combined effects of genetic polymorphisms in six selected genes on lung cancer susceptibility

Various molecular epidemiological studies have been performed to find genetic etiology for lung cancer. Particularly, genetic polymorphisms in NAD(P)H-quinone oxidoreductase (NQO1), cytochrome P450 (CYP)1A1, myeloperoxidase (MPO), glutathione-S-transferase (GST)P1, GSTT1, and GSTM1, and have been suspected to affect lung cancer risk. However, there was no study that examined the combined effects of these genes on lung cancer risk. We studied the combined genetic effects on lung cancer risk in 671 Korean subjects including 318 lung cancer patients and 353 controls. They filled questionnaires, which included lifestyle and childhood- and current environment data. Based on single nucleotide polymorphisms and gene deletions, genetic polymorphisms of the above six genes were determined with PCR-RFLP and TaqMan methods. As results, genetic polymorphisms in the GSTP1, MPO, and CYP1A1 among the genetic factors showed associations with lung cancer risk. The reference, which is supposed to have the lowest risk for cancer, was subjects who were homozygous wild type of the GSTP1 and CYP1A1 and had the MPO- mutant allele. After combination study of the three gene-polymorphism, the subjects who were most different with the reference, i.e. had the mutant allele of the GSTP1 and CYP1A1 and homozygous wild type of the MPO, showed approximately 5-fold-higher risk for lung cancer than the reference (95% CI, 2.05-12.05). Therefore, our study suggests that the combination of the GSTP1, MPO, and CYP1A1 variations affects susceptibility to lung cancer.

Relationship between glutathione S-transferase gene polymorphisms and enzyme activity in Hong Kong Chinese asthmatics

BACKGROUND

Asthma is a disease associated with oxidative stress. The glutathione S-transferases (GST) are a group of enzymes that protect cells from oxidative stress. Functional genetic polymorphisms of GST genes (GSTT1, GSTM1 and GSTP1) have previously been reported.

OBJECTIVE

To investigate the association of GST gene polymorphisms and its enzyme activity with the risk of asthma in Hong Kong Chinese adults.

METHODS

An age- and smoking status-matched case-control study was carried out on 315 patients with asthma and 315 healthy controls. Genotyping was carried out on genomic DNA using the PCR and/or restriction fragment length polymorphism (PCR-RFLP). Plasma GST activity was measured by fluorometric assay.

RESULTS

The distribution of various genotypes or alleles of the GSTT1, GSTM1 and GSTP1 was not significantly different between patients with asthma and healthy controls. The GSTM1 null genotype was found to be protective from the development of asthma in atopic subjects (odds ratios 0.55, 95% confidence interval 0.34-0.90; P=0.017). However, there was no association between GSTT1 and GSTM1 null genotypes and enzyme activity. GSTP1 codon 105 Val variants led to reduced plasma GST activity in healthy controls. Asthma patients had elevated plasma GST activity compared with healthy controls irrespective of their genotypes (P<0.001).

CONCLUSION

Our data suggest that among atopic subjects, the GSTM1 null genotype is associated with a decreased risk for asthma despite increased level of plasma GST activity in asthma, but it could not distinguish whether this increase is a potentially protective compensatory effect or a pathogenic factor.

Advances in the understanding of susceptibility to treatment-related acute myeloid leukaemia

Treatment-related acute myeloid leukaemia (t-AML) is a devastating complication following exposure to the cytotoxic and genotoxic agents used to treat a primary malignancy. Whilst the incidence of t-AML is rising, it still only occurs in a minority of patients who have received chemotherapy and/or radiotherapy treatment and hence it is important to identify factors that may confer susceptibility to the development of the condition. This paper reviews the literature and discusses the advances and limitations in our understanding of susceptibility factors to t-AML. In particular, it concentrates upon genetic polymorphisms in detoxification genes and in genes belonging to the major DNA repair pathways. This review also considers more novel susceptibility factors, such as those proposed to determine stem cell number. Increased understanding of t-AML susceptibility may enable steps to be taken to prevent its development and increase the effectiveness of treatment of the disease.

The GSTP1 Gene Is a Susceptibility Gene for Childhood Asthma and the GSTM1 Gene Is a Modifier of the GSTP1 Gene

BACKGROUND

Bronchial asthma is a chronic airway disorder characterized by bronchial inflammation. Oxidative stress is a key component of inflammation. Glutathione S-transferase P1 (GSTP1), the abundant isoform of glutathione S-transferases (GSTs) in lung epithelium, plays a key role in cellular protection against oxidative stress. Several studies have shown that the GSTP1 geneis involved in the pathogenesis of asthma and a gene-gene interaction may occur within the GST gene superfamily.

METHODS

We screened single-nucleotide polymorphisms (SNPs) at the GSTP1 locus and performed an association study in the Japanese population using two independent case-control groups (group 1: 391 pediatric patients with asthma, 462 adult patients with asthma, and 639 controls, and group 2: 115 pediatric patients with asthma and 184 controls). The effect of GSTM1 null/present genotype on the association between GSTP1 Ile105Val and asthma was also investigated.

RESULTS

We identified 20 SNPs at this locus and found this region consisted of one linkage disequilibrium block represented by four SNPs (tag SNPs). The association between the Ile105Val polymorphism in the GSTP1 gene and childhood asthma was significant in both groups (p = 0.047 in group 1, and p = 0.021 in group 2). This association was only significant in patients with GSTM1-positive genotype in both groups (group 1: GSTM1 present p = 0.013 and GSTM1 null p = 0.925, and group 2: GSTM1 present p = 0.015 and GSTM1 null p = 0.362).

CONCLUSIONS

These findings suggest that the GSTP1 gene is a childhood asthma susceptible gene, and the GSTM1 gene is a modifier gene of GSTP1 for the risk of childhood asthma in the Japanese population.

Polymorphism of XRCC1 predicts overall survival of gastric cancer patients receiving oxaliplatin-based chemotherapy in Chinese population

Pharmacogenetic advances in cancer chemotherapy have the potential to predict clinical benefit to particular regimens. Platinum agents have shown to be effective in the treatment of gastric cancer. We assessed whether single nucleotide polymorphisms (SNPs) in xeroderma pigmentosum group D (XPD), X-ray repair cross complementing group 1 (XRCC1) and glutathione S-transferase P1 (GSTP1) predicted overall survival in gastric cancer patients receiving oxaliplatin-based chemotherapy in Chinese population. SNPs of XPD-751, XRCC1-399 and GSTP1-105 in 62 gastric cancer patients were evaluated using the TaqMan 5' nuclease assay. Genotypes were correlated to survival. The median overall survival time was 322 days (range: 56-2058 days). The median survival times for patients with Arg/Arg or Arg/Gln genotypes of XRCC1 gene were significantly longer than others (P=0.03). For 58 patients with ECOG PS (Eastern Cooperative Oncology Group performance status)<or=2, more obvious significance was demonstrated (P=0.002). Patients with XRCC1-399 Gln/Gln genotype demonstrated a significant worse survival. No significant association was found between SNPs of XPD-751, GSTP1-105 and survival (P=0.125, 0.475, respectively). XRCC1 genotyping might make tailor chemotherapy possible for gastric cancer patients treated with oxaliplatin-based chemotherapy.

Insights into the role of heritable genetic variation in the pharmacokinetics and pharmacodynamics of anticancer drugs

Pharmacogenetics in oncology will ideally allow oncologists to individualise therapy based on a genetic test result. Severe toxicity and clinically significant underdosing may be avoided, whereas predicted non-responders can be offered alternative therapy. This manuscript gives an overview of heritable variants in the genes of nine enzymes or pathways that have been studied most extensively in anticancer chemotherapy. Even though many pharmacogenetic association studies have been published, there is a need for more research. In particular, there is a need for replication of data and development of predictive models. Prospective trials are required to establish clinical value and cost-effectiveness of pharmacogenetic testing in oncology.

In vitro Benzo[a]pyrene Diol Epoxide–Induced DNA Adducts and Risk of Squamous Cell Carcinoma of Head and Neck

In this large confirmatory study of 803 patients with squamous cell carcinoma of head and neck (SCCHN) and 839 controls frequency matched by age, sex, and ethnicity, we further examined potential predictors of benzo[a]pyrene diol epoxide (BPDE)-induced adduct levels and their associations with SCCHN risk. BPDE-DNA adduct levels were determined by the (32)P-postlabeling method in peripheral lymphocytes after in vitro challenged by BPDE. We also genotyped for GSTM1 null, GSTT1 null, GSTP1 Ile(105)Val, and GSTP1 Ala(114)Val. Potential predictors of BPDE-DNA adducts were evaluated by stratification and multivariate linear regression analyses and the association between adduct levels and SCCHN risk by multivariate logistic regression analyses. We found that mean BPDE-DNA adduct levels (the relative adduct labeling x 10(7) +/- SD) were significantly higher in cases (77.6 +/- 111.8) than in controls (57.3 +/- 98.3; P < 0.001). Using the median control value (29.22) as a cutoff, 63% of the cases were distributed above this level (adjusted odds ratio, 1.71; 95% confidence interval, 1.39-2.10). A significant dose-response relationship was observed between adduct quartiles and SCCHN risk (P(trend) < 0.001). Multivariate linear regression analysis revealed that ethnicity and smoking were significant predictors of BPDE-DNA adduct levels in controls. In conclusion, we confirmed the previously reported association between in vitro BPDE-induced DNA adduct levels and SCCHN risk, and the assay may help identify individuals at high risk of developing smoking-related cancers.

Detection and biochemical characterisation of a novel polymorphism in the human GSTP1 gene

The glutathione transferases (GSTs) mediate the detoxification of a broad spectrum of electrophilic chemicals. We report here the identification and characterisation of a novel naturally occurring transition that changes codon 169 from GGC (Gly) to GAC (Asp) in the human Pi class GST, GSTP1. Expression of the variant in human HepG2 cells led to a small increase in 1-chloro-2,4-dinitrobenzene (CDNB) conjugation compared to the wild-type protein. Asp(169) GSTP1-1 expressed at high levels in Escherichia coli displayed a small but significant increase in specific activity towards CDNB compared to Gly(169) GSTP1-1. The catalytic efficiency with CDNB was higher for Asp(169) GSTP1-1 compared to the wild-type enzyme, although the kinetic constants of the mutant and the wild-type enzyme towards glutathione were not different. Modelling indicated that the mutation does not appear to change protein conformation. The distribution of the genotypes in a normal healthy population (217 individuals) was 94.3% for the Gly/Gly genotype and 5.7% for the Gly/Asp genotype; no Asp/Asp genotypes were detected in this population. The frequency of the Asp(169) allele in the only oxidative stress-linked pathology that we have studied to date, i.e. alcoholic liver disease, was not significantly different from healthy controls. In conclusion, we have detected and characterised a novel SNP in GSTP1 that may play a role in modulating the activity of GSTP1-1.

Polymorphisms of glutathione S-transferase M1, T1 and P1 in patients with reflux esophagitis and Barrett's esophagus

Reflux esophagitis (RE) and Barrett's esophagus (BE) belong to the most common esophageal complications of gastroesophageal reflux disease. Glutathione S-transferase (GST) enzymes play an important role in cellular protection against oxidative stress and toxic foreign chemicals. Therefore, we investigated the hypothesis that polymorphisms in genes for these detoxifying enzymes could influence susceptibility to RE and BE. GSTM1, GSTT1 and GSTP1 loci were analyzed by PCR-based methods in 64 patients with RE (and an additional group of 22 subjects with BE as the fourth grade of esophagitis) and 173 unrelated controls. There were no significant differences in the distributions of GSTM1 and GSTT1 genotypes between the controls and patients with RE or BE. Similarly, frequencies of GSTP1 alleles were non-significantly different between the control and RE groups. However, GSTP1 B allele carriers were more frequent among the patients with BE compared to those in the reflux esophagitis group (P=0.04, OR=2.10, 95% CI 0.99-4.44) and most significantly when compared to the controls (P=0.0067, Pcorr<0.05, OR=2.56, 95%CI 1.30-5.05). Although the GSTM1 and GSTT1 genes did not show any relationship with reflux disease, the GSTP1 gene might be one of the risk factors associated with susceptibility to RE, especially to BE.

Polymorphisms of microsomal epoxide hydrolase and glutathione S-transferase P1 in a male Turkish population

Polymorphic genes encoding drug-metabolizing enzymes may account for interindividual differences in certain types of diseases especially cancer. In this study, microsomal epoxide hydrolase (EPHX1) and glutathione S-transferase P1 (GSTP1) gene polymorphisms were determined among 133 healthy males of a Turkish population. Frequencies of EPHX1 and GSTP1 gene polymorphisms were determined by using the polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) method. The observed genotype frequencies of EPHX1 exon 3 were Tyr113Tyr:50.4%, Tyr113His: 42.1%, His113His: 7.5% and EPHX1 exon 4 were His139His: 69.2%, His139Arg: 28.6%, Arg133Arg: 2.2%. GSTP1 exon 5 genotype frequencies were Ile105Ile: 58.7%, Ile105Val: 35.3%, Val105Val: 6.0% and GSTP1 exon 6 genotype frequencies were Ala114Ala: 85.0%, Ala114Val: 14.3%, Val114Val: 0.7%. These results reveal that the frequencies of EPHX1 and GSTP1gene polymorphisms in a small sampling of males within a Turkish population are similar to European Caucasian populations.

Glutathione S-transferase gene polymorphisms and risk and survival of pancreatic cancer

BACKGROUND

Pancreatic cancer is a multifactorial disease with metastasis-prone and therapy-resistant nature. The authors hypothesized that genetic variants of glutathione S-transferase (GST) affect detoxification of carcinogens and anticancer agents in the human pancreas and, thus, the risk and survival of pancreatic cancer.

METHODS

Genotypes of GSTM1, GSTT1, and GSTP1 were determined in 352 patients with pancreatic ductal adenocarcinoma and in a control group of 315 healthy, non-Hispanic whites (frequency-matched by age and sex). Survival analysis was performed in a subset of 290 patients. Epidemiological and clinical information was obtained. A multiple unconditional logistic regression model, a Cox proportional hazards model, and log-rank tests were used for statistical analysis.

RESULTS

No significant main effects of any of 3 GST genes on the risk of pancreatic cancer were observed. Subgroup analysis showed that older individuals (aged >or=62 years) who carried the GSTP1*C ((105)Val-(114)Val) containing genotype tended to have a reduced risk compared with younger individuals who carried the non-*C genotype (for sex and pack-years of smoking, the adjusted odd ratio was 0.54; 95% confidence interval [95% CI], 0.29-1.02). In a survival analysis of 138 patients who received 5-flurorouracil, patients who carried the GSTP1*C containing genotype had a significantly longer survival than patients who carried the non-*C genotype (multivariate hazard ratio, 0.45; 95% CI, 0.22-0.94).

CONCLUSIONS

The GSTP1*C variant conferred a possible protective effect against pancreatic cancer in older individuals and a significant survival advantage in patients who received 5-florouracil. The current findings must be confirmed before further inferences can be made.

Redox in redux: Emergent roles for glutathione S-transferase P (GSTP) in regulation of cell signaling and S-glutathionylation

Glutathione (GSH) provides a major source of thiol homeostasis critical to the maintenance of a reduced cellular environment that is conducive to cell survival. Mammals have accumulated a significant cadre of sulfur containing proteins, the interactive significance of which has become clear in recent times. Glutathione transferases (GST) are prevalent in eukaryotes and have been ascribed catalytic functions that involve detoxification of electrophiles through thioether bond formation with the cysteine thiol of GSH. The neutralizing impact of these reactions on products of reactive oxygen has contributed to the significant evolutionary conservation and adaptive functional redundancy of the multifaceted GSH system. Amongst the GSTs, GSTP has been implicated in tumorigenesis and in anticancer drug resistance. Emerging studies indicate that GSTP has ligand binding properties and contributes in the regulation of signaling kinases through direct protein:protein interactions. Furthermore, S-glutathionylation is a post-translational modification of low pK(a) cysteine residues in target proteins. The forward rate of the S-glutathionylation reaction can be influenced by GSTP, whereas the reverse rate is affected by a number of redox sensitive proteins including glutaredoxin, thioredoxin and sulfiredoxin. The functional importance of these reactions in governing how cells respond to oxidative or nitrosative stress exemplifies the broad importance of GSH/GST homeostasis in conditions such as cancer, ageing and neurodegenerative diseases. GSTP has also provided a platform for therapeutic drug development where some agents have completed preclinical testing and are in clinical trial for the management of cancer.

Pharmacogenetic profiling in patients with advanced colorectal cancer treated with first-line FOLFOX-4 chemotherapy

PURPOSE

The objective is to investigate whether polymorphisms with putative influence on fluorouracil/oxaliplatin activity are associated with clinical outcomes of patients with advanced colorectal cancer treated with first-line oxaliplatin, folinic acid, and fluorouracil palliative chemotherapy.

MATERIALS AND METHODS

Consecutive patients were prospectively enrolled onto medical oncology units in Central Italy. Patients were required to have cytologically/histologically confirmed metastatic disease with at least one measurable lesion. Peripheral blood samples were used for genotyping 12 polymorphisms in thymidylate synthase, methylenetetrahydrofolate reductase, xeroderma pigmentosum group D (XPD), excision repair cross complementing group 1 (ERCC1), x-ray cross complementing group 1, x-ray cross complementing protein 3, glutathione S-transferases (GSTs) genes. The primary end point of the study was to investigate the association between genotypes and progression-free survival (PFS).

RESULTS

In 166 patients, ERCC1-118 T/T, XPD-751 A/C, and XPD-751 C/C genotypes were independently associated with adverse PFS. The presence of two risk genotypes (ERCC1-118 T/T combined with either XPD-751 A/C or XPD-751 C/C) occurred in 50 patients (31%). This profiling showed an independent role for unfavorable PFS with a hazard ratio of 2.84% and 95% CI of 1.47 to 5.45 (P = .002). Neurotoxicity was significantly associated with GSTP1-105 A/G. Carriers of the GSTP1-105 G/G genotype were more prone to suffer from grade 3 neurotoxicity than carriers of GSTP1-105 A/G and GSTP1-105 A/A genotypes.

CONCLUSION

A pharmacogenetic approach may be an innovative strategy for optimizing palliative chemotherapy in patients with advanced colorectal cancer. These findings deserve confirmation in additional prospective studies.

Evaluation of genetic damage in Brazilian footwear-workers: Biomarkers of exposure, effect, and susceptibility

Employees in the footwear manufacturing industry are routinely exposed to complex mixtures of solvents used in cleaning and as diluents in glues, primers, and degreasers. The objective of this study was to determine the genotoxic effects in a group of footwear-workers occupationally exposed to solvent-based adhesive and solutions containing organic solvents, mainly toluene. Peripheral blood and buccal cells samples were collected from 39 footwear-workers (31 males and 8 females) and 55 controls (44 males and 11 females). As biomarker of exposure, we obtained data on hippuric acid (HA), the main metabolite of toluene in urine, and DNA damage detected by the Comet assay in blood cells. Micronucleus frequencies in binucleated lymphocytes (BNMN) and in epithelial buccal cells (EBCMN) were analyzed as biomarkers of effect, while polymorphisms in genes GSTT1, GSTM1, GSTP1, CYP1A1, and CYP2E1 were used as susceptibility biomarkers. Results of HA and Comet assay showed statistical increased values amongst footwear-workers relative to controls (P < or = 0.001). No differences were observed in BNMN and EBCMN frequencies between the groups, but a correlation test revealed that age was significantly associated with BNMN frequency in both control (r(s)=0.290; P < or = 0.05) and exposed groups (r(s)=0.674; P < or = 0.001). Regarding the results on genetic polymorphisms, GSTM1 null subjects from the control group showed a significant increase in EBCMN frequency relative to GSTM1 non-null subjects (P < or = 0.05). A significant increase in DNA damage detected by Comet assay in leukocytes was obtained for GSTP1 Ile/Val or Val/Val individuals from the exposed group relative to those with GSTP1 Ile/Ile (P < or = 0.05), especially in younger subjects (P < or = 0.01), and a suggestion of interaction with CYP2E1 polymorphism was found. In confirmation of these data, stepwise multiple regression analyses for selecting between the different independent variables showed that about 25% of levels of the DNA damage in footwear-worker can be associated with genetic polymorphisms in GSTP1 and CYP2E1 (P=0.006, F=5.876).

Association of GST genes polymorphisms with asthma in Tunisian children

Background. A positive association between genetic polymorphism and asthma may not be extrapolated from one ethnic group to another based on intra- and interethnic allelic and genotype frequencies differences. Objective. We assessed whether polymorphisms of GST genes (GSTM1, GSTT1, and GSTP1) are associated with asthma and atopy among Tunisian children. Methods. 112 unrelated healthy individuals and 105 asthmatic (73 atopic and 32 nonatopic) children were studied. Genotyping the polymorphisms in the GSTT1 and GSTM1 genes was performed using the multiplex PCR. The GSTP1 ILe105Val polymorphism was determined using PCR-RFLP. Results. GSTM1 null genotype was significantly associated with the increased risk of asthma (P = .002). Asthmatic children had a higher prevalence of the GSTP1Ile105 allele than the control group (43.8% and 33.5%, respectively; P = .002). Also, the presence of the GSTP1 homozygote Val/Val was less common in subjects with asthma than in control group. We have found that GSTT1 null genotype (GSTT1 *0/*0) was significantly associated with atopy (P = .008). Conclusion. Polymorphisms within genes of the GST superfamily were associated with risk of asthma and atopy in Tunisia.

Effect of glutathione S-transferase polymorphisms and proximity to hazardous waste sites on time to systemic lupus erythematosus diagnosis: results from the Roxbury lupus project

OBJECTIVE

The high prevalence of systemic lupus erythematosus (SLE) among African American women may be due to environmental exposures, genetic factors, or a combination of factors. Our goal was to assess association of residential proximity to hazardous waste sites and genetic variation in 3 glutathione Stransferase (GST) genes (GSTM1, GSTT1, and GSTP1) with age at diagnosis of SLE.

METHODS

Residential histories were obtained by interviewing 93 SLE patients from 3 predominantly African American neighborhoods in Boston. Residential addresses and locations of 416 hazardous waste sites in the study area were geocoded using ArcView software. Time-varying Cox models were used to study the effect of residential proximity to hazardous sites, GST genotype, and interaction between genotype and exposure in determining age at diagnosis.

RESULTS

The prevalence of SLE among African American women in these neighborhoods was 3.56 SLE cases per 1,000. Homozygosity for GSTM1-null and GSTP1 Ile105Val in combination was associated with earlier SLE diagnosis (P = 0.03), but there was no association with proximity to 416 hazardous sites. Available data on specific site contaminants suggested that, at a subset of 67 sites, there was higher potential risk for exposure to volatile organic compounds (P < 0.05 with Bonferroni correction). GST genotypes had a significant interaction with proximity (P = 0.03) in analyses limited to these sites.

CONCLUSION

There was no independent association between residential proximity to hazardous waste sites and the risk of earlier SLE diagnosis in this urban population. However, analysis of a limited number of sites indicated that the risk of earlier SLE associated with proximity to hazardous sites might be modulated by GST polymorphisms.