Glutathione-S-transferase gene polymorphisms in colorectal cancer patients: interaction between GSTM1 and GSTM3 allele variants as a risk-modulating factor

GSTM3 enhances radiosensitivity of nasopharyngeal carcinoma by promoting radiation-induced ferroptosis through USP14/FASN axis and GPX4

BACKGROUND

Radiotherapy is a critical treatment modality for nasopharyngeal carcinoma (NPC). However, the mechanisms underlying radiation resistance and tumour recurrence in NPC remain incompletely understood.

METHODS

Oxidised lipids were assessed through targeted metabolomics. Ferroptosis levels were evaluated using cell viability, clonogenic survival, lipid peroxidation, and transmission electron microscopy. We investigated the biological functions of glutathione S-transferase mu 3 (GSTM3) in cell lines and xenograft tumours. Co-immunoprecipitation, mass spectrometry, and immunofluorescence were conducted to explore the molecular mechanisms involving GSTM3. Immunohistochemistry was performed to investigate the clinical characteristics of GSTM3.

RESULTS

Ionising radiation (IR) promoted lipid peroxidation and induced ferroptosis in NPC cells. GSTM3 was upregulated following IR exposure and correlated with IR-induced ferroptosis, enhancing NPC radiosensitivity in vitro and in vivo. Mechanistically, GSTM3 stabilised ubiquitin-specific peptidase 14 (USP14), thereby inhibiting the ubiquitination and subsequent degradation of fatty acid synthase (FASN). Additionally, GSTM3 interacted with glutathione peroxidase 4 (GPX4) and suppressed GPX4 expression. Combining IR treatment with ferroptosis inducers synergistically improved NPC radiosensitivity and suppressed tumour growth. Notably, a decrease in GSTM3 abundance predicted tumour relapse and poor prognosis.

CONCLUSIONS

Our findings elucidate the pivotal role of GSTM3 in IR-induced ferroptosis, offering strategies for the treatment of radiation-resistant or recurrent NPC.

Antioxidant Gene Signature Impacts the Immune Infiltration and Predicts the Prognosis of Kidney Renal Clear Cell Carcinoma

Background: Oxidative stress is related to oncogenic transformation in kidney renal clear cell carcinoma (KIRC). We intended to identify a prognostic antioxidant gene signature and investigate its relationship with immune infiltration in KIRC.

Methods: With the support of The Cancer Genome Atlas (TCGA) database, we researched the gene expression and clinical data of KIRC patients. Antioxidant related genes with significant differences in expression between KIRC and normal samples were then identified. Through univariate and multivariate Cox analysis, a prognostic gene model was established and all patients were divided into high- and low-risk subgroups. Single sample gene set enrichment analysis was adopted to analyze the immune infiltration, HLA expression, and immune checkpoint genes in different risk groups. Finally, the prognostic nomogram model was established and evaluated.

Results: We identified six antioxidant genes significantly correlated with the outcome of KIRC patients as independent predictors, namely DPEP1 (HR = 0.97, P < 0.05), GSTM3 (HR = 0.97, P < 0.05), IYD (HR = 0.33, P < 0.05), KDM3B (HR = 0.96, P < 0.05), PRDX2 (HR = 0.99, P < 0.05), and PRXL2A (HR = 0.96, P < 0.05). The high- and low-risk subgroups of KIRC patients were grouped according to the six-gene signature. Patients with higher risk scores had poorer prognosis, more advanced grade and stage, and more abundance of M0 macrophages, regulatory T cells, and follicular helper T cells. There were statistically significant differences in HLA and checkpoint gene expression between the two risk subgroups. The performance of the nomogram was favorable (concordance index = 0.766) and reliably predicted the 3-year (AUC = 0.792) and 5-year (AUC = 0.766) survival of patients with KIRC.

Conclusion: The novel six antioxidant related gene signature could effectively forecast the prognosis of patients with KIRC, supply insights into the interaction between cellular antioxidant mechanisms and cancer, and is an innovative tool for selecting potential patients and targets for immunotherapy.

Akt kinase LANCL2 functions as a key driver in EGFR-mutant lung adenocarcinoma tumorigenesis

Epidermal growth factor receptor (EGFR) is a key oncogene in lung adenocarcinoma (LUAD). Resistance to EGFR tyrosine kinase inhibitors is a major obstacle for EGFR-mutant LUAD patients. Our gene chip array, quantitative polymerase chain reaction validation, and shRNA-based high-content screening identified the Akt kinase lanthionine synthetase C-like protein 2 (LANCL2) as a pro-proliferative gene in the EGFR-mutant LUAD cell line PC9. Therefore, we investigated whether LANCL2 plays a role in promoting cell proliferation and drug resistance in EGFR-mutant LUAD. In silico clinical correlation analysis using the Cancer Genome Atlas Lung Adenocarcinoma dataset revealed a positive correlation between LANCL2 and EGFR expression and an inverse relationship between LANCL2 gain-of-function and survival in LUAD patients. The EGFR-mutant LUAD cell lines PC9 and HCC827 displayed higher LANCL2 expression than the non-EGFR-mutant cell line A549. In addition, LANCL2 was downregulated following gefitinib+pemetrexed combination therapy in PC9 cells. LANCL2 knockdown reduced proliferation and enhanced apoptosis in PC9, HCC827, and A549 cells in vitro and suppressed murine PC9 xenograft tumor growth in vivo. Notably, LANCL2 overexpression rescued these effects and promoted gefitinib + pemetrexed resistance in PC9 and HCC827 cells. Pathway analysis and co-immunoprecipitation followed by mass spectrometry of differentially-expressed genes in LANCL2 knockdown cells revealed enrichment of several cancer signaling pathways. In addition, Filamin A and glutathione S-transferase Mu 3 were identified as two novel protein interactors of LANCL2. In conclusion, LANCL2 promotes tumorigenic proliferation, suppresses apoptosis, and promotes gefitinib+pemetrexed resistance in EGFR-mutant LUAD cells. Based on the positive association between LANCL2, EGFR, and downstream Akt signaling, LANCL2 may be a promising new therapeutic target for EGFR-mutant LUAD.

Association of GSTM1 and GSTT1 Null Deletions and GSTP1 rs1695 Polymorphism with the Risk of Hepatocellular Carcinoma: A Systematic Review and Meta-analysis

Context: Hepatocellular carcinoma (HCC), as the most common type of primary liver cancer (accounting for 70% - 90% of all liver cancers), is the seventh most common malignancy worldwide. Glutathione S-transferases (GSTs) are a specific group of enzymes that are responsible for the detoxification of carcinogens. According to the available literature, genetic variations in this group of enzymes may be associated with the risk of HCC. In this study, we aimed to assess the association of GSTM1 and GSTT1 null deletions and GSTP1 rs1695 polymorphism with the risk of HCC. Methods: We systematically searched electronic databases, including PubMed, Scopus, and Web of Science, using appropriate keywords to gather relevant data until March 2019. Studies that met the inclusion criteria were included in the meta-analysis, using either fixed- or random-effects models based on the presence of heterogeneity. Results: This meta-analysis pooled 19 studies for GSTM1 null deletions, 14 studies for GSTT1 null deletions, and five studies for GSTP1 rs1695 polymorphism. In terms of heterogeneity, the pooled odds ratio (OR) was calculated in a random-effects model for both Asian and non-Asian populations. HCC was found to be associated with GSTM1 null deletions (OR = 1.26, 95% CI: 1.00 - 1.58, P = 0.05) and GSTT1 null deletions (OR = 1.39, 95% CI: 1.10 - 1.74, P = 0.005); however, no significant association was found between HCC and GSTP1 rs1695 polymorphism (OR = 1.14, 95% CI: 0.86 - 1.50, P = 0.36). Conclusions: We found that GSTM1 and GSTT1 null deletions increased the risk of HCC; however, the GSTP1 rs1695 polymorphism did not have a similar effect.

GSTM3 Function and Polymorphism in Cancer: Emerging but Promising

Cancer is a major cause of human mortality; however, the molecular mechanisms and proteomic biomarkers that cause tumor progression in malignant tumors are either unknown or only partially revealed. Glutathione S-transferases mu3 (GSTM3), which belongs to a family of xenobiotic detoxifying phase II enzymes, is associated with carcinogen detoxification and the metabolism of exogenous electrophilic substances. It has been reported that GSTM3 has different polymorphisms in various tumor cells and regulates tumorigenesis, cell invasion, metastasis, chemoresistance, and oxidative stress. Deep research into the regulatory mechanisms involved in disorders of GSTM3 expression and the function of GSTM3 in different cancers may facilitate improvements in cancer prevention and targeted therapy. The combination of GSTM3 with other family members can regulate the carcinogenesis and susceptibility to different cancers in humans. GSTM3 also regulates the reactive oxygen species (ROS) and participates in oxidative stress-mediated pathology. Here, we provide a general introduction to GSTM3 in order to better understand the role of GSTM3 in cancer.

Glutathione S-Transferase Mu-3 Predicts a Better Prognosis and Inhibits Malignant Behavior and Glycolysis in Pancreatic Cancer

Background: Pancreatic cancer (PC) is a lethal malignancy with an extremely unfavorable 5-year survival rate and a high mortality rate. Glutathione S-transferase mu-3 (GSTM3) has been shown to exert different functions in the progression and development of various cancers, except for PC. This study aimed to explore the role of GSTM3 in the malignant behavior and metabolic aspects of PC, its clinical significance, and its possible molecular mechanism in pancreatic cancer.

Methods: Tumor microarrays of pancreatic ductal adenocarcinoma (PDAC) were used to evaluate the clinicopathological variables and GSTM3 expression by immunohistochemical staining. Kaplan–Meier survival and Cox regression analyses were further performed to assess the prognosis. The effect of GSTM3 on PC aggressiveness was detected using overexpressing and silencing transfection methods. Western blot, RT-qPCR, CCK-8, and cell cycle assay were applied to evaluate the expression level and proliferation. A xenograft animal model was assessed. Reactive oxygen species (ROS) were measured using the laser confocal scanner and glycolysis was detected using an Agilent Seahorse kit. RNA sequencing was used to assess the underlying mechanism and the signaling pathway involved.

Results: GSTM3 was relatively poorly expressed in PDAC tissues compared to para-tumoral tissues and a high level of GSTM3 indicated good overall survival. Functionally, overexpression of GSTM3 could significantly inhibit cell proliferation by delaying the G0/G1 transition, whereas the opposite results were found in the GSTM3 downregulation group. In addition, xenograft animal models further confirmed the effect on proliferation. Moreover, silencing of GSTM3 induced ROS accumulation and promoted glycolysis in PC, indicating its tumor suppressive effect, and vice versa when GSTM3 was upregulated. Finally, RNA sequencing results demonstrated that GSTM3 facilitates anti-tumorigenicity partly via the JAK-STAT signaling pathway in PC.

Conclusion: GSTM3 inhibited tumor progression and altered the metabolic pattern in PC. This may be a potential predictive biomarker in PC and a prospective therapeutic target.

Individual and combined effects of GSTM1 and GSTT1 polymorphisms on colorectal cancer risk: an updated meta-analysis

BACKGROUND

The presence or absence of glutathione S-transferase M1 gene (GSTM1) and glutathione S-transferase T1 gene (GSTT1) polymorphisms, and their combined effects have been suggested as a risk factor for colorectal cancer (CRC). However, the results are inconsistent.

OBJECTIVES

An updated meta-analysis was performed to solve the controversy.

METHODS

Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines were used.

RESULTS

Overall, the GSTM1 null genotype was associated with an increased CRC risk in Caucasians (odds ratio (OR) = 1.14, 95% confidence interval (CI): 1.05-1.23), Asians (OR = 1.19, 95% CI: 1.08-1.32), high-quality studies (OR = 1.12, 95% CI: 1.06-1.18). Moreover, the GSTM1 null genotype was also associated with an increased colon cancer risk (OR = 1.32, 95% CI: 1.16-1.51). The GSTT1 null genotype was also associated with an increased CRC risk in Asians (OR = 1.08, 95% CI: 1.02-1.15) and Caucasians (OR = 1.24, 95% CI: 1.09-1.41). Moreover, The GSTT1 null genotype was associated with an increased rectal cancer risk (OR = 1.13, 95% CI: 1.01-1.27, I2 = 8.3%) in subgroup analysis by tumor location. Last, the GSTM1 null/GSTT1 null genotype was associated with an increased CRC risk in Asians.

CONCLUSION

This meta-analysis indicates that the GSTM1 and GSTT1 null genotypes are associated with increased CRC risk in Asians and Caucasians, and the GSTM1 null/GSTT1 null genotype was associated with increased CRC risk in Asians.

Sex disparities in cancer

Sex is a key biological factor affecting the development of many cancer types. There are considerable differences between male and female subpopulations in terms of cancer incidence, prognosis and mortality. Recent studies have extensively characterized the sex-biased molecular changes in cancer patients. Further efforts should be made to develop sex-specific cancer prevention and therapeutic strategies.

GSTM1 and GSTT1 copy number variants and the risk to Thai females of hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is a common malignancy found throughout the world that most often occurs in males. The cancer is associated with many risk factors such as viral infection, cirrhosis, alcohol, smoking, and fungal toxins. GSTM1 and GSTT1 are detoxification enzymes activated by the cleansing of carcinogenic compounds. Low DNA copy numbers of Glutathione S-transferases M1 and T1 result in a loss of enzyme activity, which causes carcinogenesis factors. DNA copy number variants (CNVs) were determined to compare the differences between the frequencies of GSTM1 and GSTT1 in a control group and patients. Then, the association of these genes with the pathological/survival status of HCC patients was investigated.

Methods

Forty-nine Thai HCC patients' DNA and the genomic DNA of 66 healthy controls were investigated for GSTM1 and GSTT1 CNVs by real-time polymerase chain reaction (PCR). Then, the correlations between GSTM1 and GSTT1 patients' CNVs, the control group, and clinico-pathological parameters were determined.

Results

The results show that were no differences between the CNVs of GSTM1 and GSTT1 in the controls and patients (P≥0.05). Only GSTT1 genotypes 0/0 correlated to an increase in the risk of hepatocellular carcinogenesis (OR value was 1.88). GSTM1 CNVs were associated with the gender of patients (P=0.002). However, no correlations were found between GSTT1 CNVs and any of the clinico-pathological parameters.

Conclusions

The results suggest that only GSTT1 CNVs are associated with increased risk factors of HCC in Thais. GSTM1 copy numbers had a dominant correlation with female HCC patients.

GSTM3 and GSTP1: novel players driving tumor progression in cervical cancer

The molecular processes and proteomic markers leading to tumor progression (TP) in cervical cancer (CC) are either unknown or only partially understood. TP affects metabolic and regulatory mechanisms that can be identified as proteomic changes. To identify which proteins are differentially expressed and to understand the mechanisms of cancer progression, we analyzed the dynamics of the tumor proteome in CC cell lines. This analysis revealed two proteins that are up-regulated during TP, GSTM3 and GSTP1. These proteins are involved in cell maintenance, cell survival and the cellular stress response via the NF-κB and MAP kinase pathways during TP. Furthermore, GSTM3 and GSTP1 knockdown showed that evasion of apoptosis was affected, and tumor proliferation was significantly reduced. Our data indicate the critical role of GST proteins in the regulation and progression of cervical cancer cells. Hence, we suggest GSTM3 and GSTP1 as novel biomarkers and potential therapeutic targets for treating cervical cancer.

SIGNIFICANCE

CC is particularly hazardous in the advanced stages, and there are few therapeutic strategies specifically targeting these stages. We performed analyses on CC tumor proteome dynamics and identified GSTM3 and GSTP1 as novel potential therapeutic targets. Knockdown of these proteins showed that they are involved in cell survival, cell proliferation and cellular evasion of apoptosis.

Interaction between GSTT1 and GSTP1 allele variants as a risk modulating-factor for autism spectrum disorders

We investigated the role of glutathione S-transferase (GST) genes in Autism Spectrum Disorder (ASD). We used data from 111 pairs of age- and sex-matched ASD cases and typically developing (TD) controls between 2-8 years of age from Jamaica to investigate the role of GST pi 1 (GSTP1), GST theta 1 (GSTT1), and GST mu 1 (GSTM1) polymorphisms in susceptibility to ASD. In univariable conditional logistic regression models we did not observe significant associations between ASD status and GSTT1, GSTM1, or GSTP1 genotype (all P > 0.15). However, in multivariable conditional logistic regression models, we identified a significant interaction between GSTP1 and GSTT1 in relation to ASD. Specifically, in children heterozygous for the GSTP1 Ile105Val polymorphism, the odds of ASD was significantly higher in those with the null GSTT1 genotype than those with the other genotypes [Matched Odds Ratio (MOR) = 2.97, 95% CI (1.09, 8.01), P = 0.03]. Replication in other populations is warranted.

Role of NSD1 in H2O2-induced GSTM3 suppression

Nuclear receptor-binding SET domain-containing protein 1 (NSD1) has been proved to act as a histone methyltransferase and a transcription co-factor to regulate gene expression. However, the role of NSD1 in oxidative stress remains poorly understood. In the present study, we focused on the NSD1 regulation of antioxidant enzyme gene glutathione S-transferase M3 (GSTM3) expression in response to oxidative stress. H2O2 treatment caused the decrease of both NSD1 and GSTM3 expression, and the depletion of NSD1 expression by specific siRNA reversed the H2O2-reduced GSTM3 expression. Furthermore, we investigated NSD1 modulating the transcription of GSTM3 promoter with -63A/C polymorphism closed to TATA box in response to H2O2 by luciferase and in vitro or in vivo DNA-protein binding assays. The promoter activity of GSTM3 with -63A was higher than -63C, and was increased or decreased by the overexpression or depletion of NSD1, but -63C was not influenced. H2O2 repressed the promoter activity of GSTM3 with -63A more than -63C, and the depletion of NSD1 expression weakened H2O2 inhibition on the -63A promoter, but augmented H2O2 inhibition on the -63C promoter. In addition, NSD1 interacted with RNAPII and bound to GSTM3 -63A/C TATA box, with higher binding affinity to -63A than to -63C. These data indicated that NSD1 implicated in H2O2-induced oxidative stress, and H2O2-induced NSD1 suppression resulted in the decrease of GSTM3 expression through the -63A/C TATA box.

A systemic review of glutathione S-transferase P1 Ile105Val polymorphism and colorectal cancer risk

OBJECTIVES

To investigate the correlation between glutathione S-transferase P1 (GSTP1) Ile105Val polymorphism and colorectal cancer (CRC) risk.

METHODS

Studies were identified to investigate the association between GSTP1 Ile105Val polymorphism and CRC risk. Systematic computerized searches of the PubMed, Chinese National Knowledge Infrastructure, WANFANG and SinoMed were performed. Summary odds ratios (OR) and 95% confidence intervals (95% CI) were used to measure GSTP1 Ile105Val polymorphisms and CRC risk.

RESULTS

A total of 23 retrospective studies were included in the meta-analysis. During all studies including 6,981 cases and 8,977 controls, sample sizes ranged from 146 to 2,144. Overall, the pooled results revealed that Ile105Val polymorphism was not associated with CRC risk and confused results were found in subgroup analyses. Further meta-analyses were conducted after excluding low-quality studies. GSTP1 Ile105Val is associated with increased risk of CRC limited in studies with matched control. There was no significant heterogeneity in all genetic comparisons, but heterogeneity existed in subgroup analyses of heterozygous and dominant comparisons. The meta-regression analyses indicated that matched controls were the significant factor influencing between-study heterogeneity in all possible influential factors including published year, ethnicity, source of control, sample size, Hardy-Weinberg equilibrium (HWE) in control and matched controls. Sensitivity analysis revealed the pooled ORs were not changed before and after removal of each single study in all genetic comparisons, indicating the robustness of the results.

CONCLUSIONS

GSTP1 Ile105Val might be associated with increased risk of CRC. However, more high-quality case-control studies should be performed to confirm the authenticity of our conclusion.

Genetic modifiers of cancer risk in Lynch syndrome: a review

The report by Aldred Scott Warthin in 1913 of a cancer family history and expanded on by Henry T. Lynch demonstrated one of the most enduring traits observed in patients with Lynch syndrome. The recognition of a variety of malignancies occurring at differing ages within a single family suggested the role of genetic variance on disease expression in an autosomal dominantly inherited genetic condition. With the identification of the genetic basis of Lynch syndrome and the subsequent collection of families and their medical records it has become possible to identify subtle genetic effects that influence the age at which disease onset occurs in this cancer predisposition. Knowledge about genetic modifiers influencing disease expression has the potential to be used to personalise prophylactic screening measures to maximise the benefits for family members and their carers.

Genetic polymorphism of glutathione S-transferase P1 (GSTP1) in Delhi population and comparison with other global populations

Glutathione S-transferases (GSTs) belong to a super family of phase II detoxification enzymes, which play an important role in protecting cells from damage caused by endogenous and exogenous compounds by conjugating reactive intermediates with glutathione to produce less reactive water-soluble compounds. In the present study, we determined the frequencies of two polymorphisms in exon 5 and exon 6 of GSTP1 gene in 500 normal individuals from Delhi. GSTP1 polymorphism was analysed by PCR-RFLP using amplification refractory mutation system (ARMS) assay. Two polymorphic sites in GSTP1 (Ile105 → Val105; Ala114 → Val114) have been analysed simultaneously, which results in four alleles: GSTP1*A (wild-type Ile105; Ala114), GSTP1*B (Val105; Ala114), GSTP1*C (Val105; Val114) and GSTP1*D (Ile105; Val114). The GSTP1 allele frequency in Delhi population was 0.663, 0.248, 0.069, and 0.020 for GSTP1*A, GSTP1*B, GSTP1*C, and GSTP1*D respectively. The frequency of Ile105 and Val105 allele was 0.683 and 0.317 respectively and it was calculated for the purpose of comparison with published data where all the four alleles were not analysed. GSTP1 alleles from Delhi population were compared with reported frequencies from all over India, and from other ethnic groups worldwide. This study would provide a basic database for future genetic studies.

GSTM3 A/B polymorphism and risk for head and neck cancer: a meta-analysis

Background

Glutathione S-transferase M3 (GSTM3) is an important member of the GSTs that plays a critical role in the development of head and neck cancer (HNC). Several studies have investigated between the GSTM3 A/B polymorphism and risk of HNC, however, the results remain controversial. The aim of this meta-analysis is to evaluate the association between the GSTM3 A/B polymorphism and the risk of HNC.

Methods

All eligible case-control studies published up to July 2013 were identified by searching PubMed and Web of Science. The HNC risk associated with the GSTM3 A/B polymorphism was estimated for each study by odds ratios (OR) together with its 95% confidence interval (CI), respectively.

Results

Fourteen studies from ten publications with 2110 patients and 2259 controls were included. Overall, the GSTM3 A/B polymorphism was associated with a decreased risk of HNC using the dominant model, homozygote comparison model and heterozygote comparison model (OR = 0.82, 95%CI: 0.71–0.94; OR = 0.67, 95%CI: 0.49–0.94; and OR = 0.84, 95%CI: 0.73–0.97, respectively); besides, in stratification analyses by ethnicity, similar results were observed in Caucasian populations. Stratification by tumor site indicated that the GSTM3 polymorphism was associated with a decreased risk of laryngeal cancer under recessive model and homozygote comparison (OR = 0.52, 95%CI: 0.30–0.89; and OR = 0.50, 95%CI: 0.29–0.87, respectively); By stratifying source of control, decreased cancer risk was observed in hospital-based population under all genetic models (OR = 0.67, 95%CI: 0.56–0.81 for the dominant model; OR = 0.66, 95%CI: 0.46–0.95 for the recessive model; OR = 0.55, 95%CI: 0.37–0.83 for the homozygote comparison model, and OR = 0.70, 95%CI: 0.58–0.84 for the heterozygote comparison model).

Conclusions

This meta-analysis suggests that the GSTM3 A/B polymorphism may be an important protective factor for HNC, especially of laryngeal cancer and Caucasian populations.

Glutathione S-transferase T1 gene polymorphism and colorectal cancer risk: an updated analysis

BACKGROUND AND OBJECTIVE

The association between glutathione S-transferase T1 (GSTT1) gene polymorphisms and colorectal cancer (CRC) susceptibility is still controversial. In order to clarify the effect of GSTT1 genotype on the CRC risk, we carried out an updated meta-analysis of published case-control studies to provide more precise evidence.

METHODS

Two investigators independently searched the databases of Pubmed, EMBASE and China National Knowledge Infrastructure (CNKI) up to October 15, 2012. Crude odds ratios (OR) and 95% confidence intervals (CI) were calculated to investigate the strength of the association in a fixed- or random-effects model depending on statistical heterogeneity.

RESULTS

Forty-six case-control studies with 15,373 colorectal cancer cases and 21,238 controls were included. Overall, the pooled results indicated that GSTT1 null genotype was significantly associated with increased CRC risk (OR=1.21, 95% CI=1.10-1.33). When stratifying for ethnicity and control sources, we also observed positive association between GSTT1 null genotype and increased risk of CRC. When stratifying by the location, we found there was a statistically significant association in the rectal cancer (OR=1.28, 95% CI=1.01-1.64), but not in colon cancer (OR=1.27, 95% CI=0.94-1.73). Subgroup analyses for Dukes stage, histological differentiation of CRC and smoking habit did not reveal any significant differences in genotype distribution. In addition, we observed a strong correlation between increased CRC risk and the combined GSTM1 and GSTT1 null genotype.

CONCLUSIONS

This meta-analysis suggests that the GSTT1 null genotype may contribute to increased risk of colorectal cancer. More well-designed studies based on larger population are needed to confirm our results.

Polymorphisms of glutathione-S-transferases M1, T1, P1 and susceptibility to colorectal cancer in a sample of the Tunisian population

In this study, we investigated the associations of polymorphisms in glutathione-S-transferases (GSTs) genes that are GSTM1, GSTT1, and GSTP1, with sporadic colorectal cancer (CRC). Hundred and fifty patients with CRC and 128 healthy controls were genotyped. DNA was isolated from blood samples. Polymorphisms were assessed by polymerase chain reaction-restriction fragment length polymorphism-based methods and polymerase chain reaction multiplex. Logistic regression analyses showed significant risk for CRC associated with GSTP1 homozygotes for Val-105 (OR 4.82; 95 % CI 1.97-11.80) or for individuals who possessed at least one Val-105 allele (OR 2.54; 95 % CI 1.751-3.703). There were no statistically significant differences in the frequency of GSTM1- and GSTT1-null genotypes (p > 0.05). The GSTM1-null was found in 70.47 % of all cases and 70.07 % of controls (OR 0.61; 95 % CI 0.33-1.12). The GSTT1-null genotype was found in 38.77 % of cases and 49.22 % of controls (OR 1.53; 95 % CI 0.94-2.47). No effect of any genotype for GSTM1 and GSTT1 on CRC was detected. But then an association between the polymorphism of the GSTP1 and the CRC susceptibility was detected.

The GSTP1 Ile105Val polymorphism is not associated with susceptibility to colorectal cancer

The glutathione S transferase (GST) family is a major part of cellular defense mechanisms against endogenous and exogenous substances, many of which have carcinogenic potential. Alteration in the expression level or structure of the glutathione-S-transferase (GST) enzymes may lead to inadequate detoxification of potential carcinogens and consequently contribute to cancer development. A member of the glutathione-S-transferase (GST) family, GSTP1, is an attractive candidate for involvement in susceptibility to carcinogen-associated colorectal cancer. An A>G transition in exon 5 resulting in an Ile105Val amino acid substitution has been identified which alters catalytic efficiency. The present study investigated the possible impact of Ile105Val GSTP1 polymorphism on susceptibility to colorectal cancer. in Jordan We examined 90 tissue samples previously diagnosed with colorectal carcinoma, and 56 non-cancerous colon tissues. DNA was extracted from paraffin embedded tissues and the status of the GSTP1 polymorphism was determined using a polymerase chain reaction restriction fragment length polymorphism (RFLP) method. No statistically significant differences were found between colorectal cancer cases and controls for the GSTP1 Ile/Ile, Ile/Val and Val/Val genotypes. The glutathione S-transferase polymorphism was not associated with risk in colorectal cancer cases in Jordan stratified by age, sex, site, grade or tumor stage. In conclusion, the GSTP1 Ile105Val polymorphism is unlikely to affect the risk of colorectal cancer.

Tissue-based proteomics reveals FXYD3, S100A11 and GSTM3 as novel markers for regional lymph node metastasis in colon cancer

Regional lymph node metastasis negatively affects prognosis in colon cancer patients. The molecular processes leading to regional lymph node metastasis are only partially understood and proteomic markers for metastasis are still scarce. Therefore, a tissue-based proteomic approach was undertaken for identifying proteins associated with regional lymph node metastasis. Two complementary tissue-based proteomic methods have been employed. MALDI imaging was used for identifying small proteins (≤25 kDa) in situ and label-free quantitative proteomics was used for identifying larger proteins. A tissue cohort comprising primary colon tumours without metastasis (UICC II, pN0, n = 21) and with lymph node metastasis (UICC III, pN2, n = 33) was analysed. Subsequent validation of identified proteins was done by immunohistochemical staining on an independent tissue cohort consisting of primary colon tumour specimens (n = 168). MALDI imaging yielded ten discriminating m/z species, and label-free quantitative proteomics 28 proteins. Two MALDI imaging-derived candidate proteins (FXYD3 and S100A11) and one from the label-free quantitative proteomics (GSTM3) were validated on the independent tissue cohort. All three markers correlated significantly with regional lymph node metastasis: FXYD3 (p = 0.0110), S100A11 (p = 0.0071), and GSTM3 (p = 0.0173). FXYD3 and S100A11 were more highly expressed in UICC II patient tumour tissues. GSTM3 was more highly expressed in UICC III patient tumour tissues. By our tissue-based proteomic approach, we could identify a large panel of proteins which are associated with regional lymph node metastasis and which have not been described so far. Here we show that novel markers for regional lymph metastasis can be identified by MALDI imaging or label-free quantitative proteomics and subsequently validated on an independent tissue cohort.

Pharmacogenomics of cisplatin-based chemotherapy in ovarian cancer patients of different ethnic origins

AIM

There is a substantial difference between Asians and Caucasians in their reaction to platinum drugs. To determine whether population-related genomics contribute to differences in patient outcomes, pharmacogenomic relevance of polymorphisms in some genes, the protein activities of which may affect aspects of cisplatin metabolism, were evaluated.

PATIENTS & METHODS

Nineteen polymorphisms in ten genes were tested for correlations with the efficacy and toxicity of a cisplatin-cyclophosphamide regimen in Yakut and Russian patients with ovarian cancer.

RESULTS

The CYP2E1 7632T>A polymorphism was associated with progression-free survival (p = 0.015) in Yakuts. In Russians, progression-free survival was correlated with the GSTP1 Ile105Val polymorphism (p = 0.004). Yakut patients with the GSTT1-null genotype had a higher risk for nephrotoxicity. By contrast, in the Russian group, nephrotoxicity was more frequent among patients with heterozygous ERCC1 genotypes. Severe emesis in Yakuts was independently associated with two polymorphisms in the CYP2E1 gene but in Russians, it was more common in patients with the GSTT1-null genotype. Differences in genotypic correlations with anemia were also observed.

CONCLUSION

Significant differences in genotype distribution between Russian and Yakut women were observed for ten of the 19 polymorphisms, but none of them seemed to be a clear casual candidate and further studies involving more markers are required.

Association of xenobiotic metabolizing enzymes genetic polymorphisms with esophageal cancer in Kashmir Valley and influence of environmental factors

The Kashmir Valley has an elevated incidence rate of esophageal cancer (EC). Several environmental and genetic factors have been suspected for development of EC. A case-control study was performed in 135 EC patients and 195 healthy controls to analyze association of polymorphisms in glutathione S-transferase (GST) mu (GSTM1), GST theta (GSTT1), GST pi (GSTP1), GSTM3, Cytochrome P450 (CYP)1A1, and CYP2E1 genes with susceptibility to EC as well as their interaction with environmental factors such as smoking and high consumption of salted tea in Kashmir valley. All subjects were genotyped through polymerase chain reaction restriction fragment length polymorphism. Data was statistically analyzed using the chi-square test and logistic regression model. Results showed that GSTP1313 val/val and CYP2E1c1c2 genotypes imparted risk for esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma [EADC; odds ratio (OR) = 3.24, 95% confidence interval (CI) = 1.30-8.05; OR = 4.20, 95% CI = 1.65-10.70], respectively. GSTM3AB genotype/B allele was found to be associated with low risk for EC. Tobacco smoking through hukka (water pipe) and consumption of salted tea itself were high risk factors for developing EC (OR = 21.44, 95% CI = 11.63-39.54; OR = 14.86, 95% CI = 8.41-26.24), and the risks were modulated through the interaction of GSTM3AB, GSTP1val/val genotypes. In conclusion, GSTP1val/val and CYP2E1c1c2 genotypes/c2 allele increased the risk of ESCC and EADC, respectively, in the Kashmiri population; whereas GSTM3AB genotype imparted lower risk for both ESCC and EADC.

Glutathione S-transferase M1 polymorphism and sporadic colorectal cancer risk: An updating meta-analysis and HuGE review of 36 case-control studies

PURPOSE

Sporadic colorectal cancer (CRC) is considered to be a multifactorial disease, in which multiple exposures to endogenous factors interact with individual genetic background in a complex manner, resulting in modulation of the risk. The glutathione S-transferase M1 gene (GSTM1) is a particularly attractive candidate for CRC susceptibility because it codes an enzyme involved in the metabolism of environmental carcinogens. However, the epidemiological findings have been inconsistent.

METHODS

To evaluate this association, we performed an extensive meta-analysis of 36 case-control studies (including 10,009 cases and 15,070 controls).

RESULTS

Overall, the combined data showed that GSTM1 deficiency is associated with a marginal effect on CRC risk (odds ratio [OR] = 1.13; 95% confidence interval [CI]: 1.03-1.23; P for heterogeneity <0.001). When stratified by race and tumor site, significant results were only observed in Caucasians (OR = 1.14, 95% CI: 1.01-1.27; P for heterogeneity <0.001), whereas no increased risk was detected in other subgroups.

CONCLUSIONS

The findings of our study support the suggestion that GSTM1 polymorphism is associated with an increased risk of CRC, especially in the Caucasian population. Further investigation into the association between GSTM1 polymorphism and the risk of CRC is warranted and should include larger sample sizes and other genetic polymorphisms in metabolism of environmental carcinogens.

GSTM1, GSTT1, GSTP1, GSTA1 and colorectal cancer risk: a comprehensive meta-analysis

Glutathione S-transferases (GSTs) catalyse reactions between glutathione and lipophilic compounds with electrophilic centres, leading to neutralisation of toxic compounds, xenobiotics and products of oxidative stress. Controversy exists about whether GST polymorphisms (GSTM1 null/present genotype, GSTT1 null/present genotype, GSTP1 Ile105Val and GSTA1 *A/*B) represent risk factors for colorectal cancer. This meta-analysis aims to examine the associations between the above-mentioned polymorphisms and colorectal cancer risk. Forty-four studies were eligible for GSTM1 (11,998 colorectal cancer cases, 17,552 controls), 34 studies for GSTT1 (8596 cases, 13,589 controls), 19 studies for GSTP1 (5421 cases, 7671 controls) and four studies for GSTA1 polymorphism (1648 cases, 2039 controls). Pooled odds ratios (ORs) were appropriately derived from fixed-effects or random-effects models. Separate analyses were conducted on Caucasian and Chinese populations. Where appropriate, sensitivity analysis concerning the deviation of genotype frequencies in controls from the Hardy-Weinberg equilibrium was performed. GSTM1 null allele carriers exhibited increased colorectal cancer risk in Caucasian populations (pooled OR=1.150, 95% confidence interval (CI): 1.060-1.248, random effects); no significant association was detected for Chinese subjects (pooled OR=1.025, 95% CI: 0.903-1.163, fixed effects). Similarly, GSTT1 null allele carriers exhibited increased colorectal cancer risk in Caucasian populations (pooled OR=1.312, 95% CI: 1.119-1.538, random effects); the association in Chinese subjects was not significant (pooled OR=1.068, 95% CI: 0.788-1.449, random effects). Concerning GSTP1 Ile105Val no significant associations were demonstrated in either race. GSTA1 *A/*B polymorphism was not associated with colorectal cancer risk. GSTM1 and GSTT1 null genotypes confer additional risk for colorectal cancer in Caucasian populations.

Gender-related differences in response to mutagens and carcinogens

The incidences of many cancers can be very different in men and women. Besides differences in exposures to putative causative agents, it is plausible that both genetic and epigenetic effects play roles in these differences. In addition, gender-specific lifestyle and behavioural factors may modulate the effects of exposure to genotoxins. This commentary focuses on several aspects of gender-related differences in responses to mutagens and carcinogens, including sensitivity to chromosome damage, the contribution of genotypic variation and the role of DNA methylation. It is concluded that the reasons for gender differences in cancer susceptibility remain largely unknown in many cases, and the subject deserves more attention and study.

An updating meta-analysis of the glutathione S-transferase T1 polymorphisms and colorectal cancer risk: a HuGE review

INTRODUCTION

GSTT1 status has been extensively studied as a colorectal cancer risk factor. However, the results are inconsistent. To examine this controversy, we performed a meta-analysis to evaluate the relationship between GSTT1 polymorphism and colorectal cancer.

MATERIALS AND METHODS

We performed a literature search using PUBMED, EMBASE, Cochrane Library, and HuGNet database to February 2009, with no restrictions. All articles were independent and contained the minimum information necessary to estimate the colorectal cancer risk associated with GSTT1 null. Summary odds ratio (ORs) and 95% confidence intervals (CIs) were calculated using random-effect or fixed-effect models based on the heterogeneity of included studies.

RESULTS

A total of 23 case-control studies, including a total of 11,057 subjects (5,058 cases and 5,999 controls), that related to GSTT1 polymorphism and risk of colorectal cancer were identified and included for analysis. The random-effect meta-analyses of all the 23 studies suggested that there was a small increased risk of colorectal cancer for individuals with GSTT1 null (OR was 1.23; 95% CI 1.02-1.49; I (2) = 76.9%, P for heterogeneity <0.001). The fixed-effect meta-analyses reached a similar results in Caucasians populations of ten studies (OR = 1.39; 95% CI 1.21-1.59; I (2) = 29.8%, P for heterogeneity = 0.171) and Asians populations of five studies (OR = 1.23; 95% CI 1.04-1.45; I (2) = 0.0%, P for heterogeneity = 0.428), with as inversely association in the other ethnic populations from four studies (OR = 0.69; 95% CI 0.54-0.877; I (2) = 0.0%, P for heterogeneity = 0.58).

CONCLUSION

There was a small increased risk of colorectal cancer for individuals with GSTT1 null, especially for Caucasians populations and Asian populations.

Genetic polymorphisms and the efficacy and toxicity of cisplatin-based chemotherapy in ovarian cancer patients

Platinum drugs are among the most active and widely used agents in the treatment of different cancers. However, the great individual variability in both outcome and toxicity of platinum chemotherapy requires the identification of genetic markers that can be used to screen patients before treatment. In this study, 21 polymorphisms in 10 genes, the protein activities of which may be addressed in different aspects of cisplatin metabolism, were tested for correlations with efficacy and toxicity of cisplatin-cyclophosphamide regimen in 104 ovarian cancer patients. The glutathione S-transferase P1 (GSTP1) Ile105Val polymorphism was strongly associated with progression-free survival (chi(2)=12.12, P=0.002). The allelic status of the GSTA1 -69 C>T polymorphism correlated with the overall survival: patients with T/T genotype survived longer than C/C carriers (P=0.044). Thrombocytopenia, anemia and neuropathy were less frequent among patients with the GSTM1-null or GSTM3 intron 6 AGG/AGG genotypes. Severe neutropenia was associated with the TP53 72 Pro/Pro, XPD 312 Asp/Asn and XRCC1 399 Arg/Arg genotypes. A higher risk of nephrotoxicity was noted for patients with the heterozygous ERCC1 19007 T/C and 8092 C/A genotypes. No correlations were found between genotypes and complete tumor responses.

[Genetic polymorphism in patients with colorectal and with head and neck cancer]

Colorectal cancer is the second most frequent cause of death among malignant diseases. The mortality of head and neck cancer in Hungary increased by 265 percent in the last thirty years. Both malignancies belong to the most current public health problems in Hungary. The influence of two allelic polymorphisms of GSTM1 and GSTT1, and that of p53 gene codon 72 on colon cancer was investigated. In case of head and neck cancer the effects of the Arg194Trp and Arg399Gln polymorphisms of XRCC1 gene were analyzed. Intraoperative removed tissue samples were processed and cancer free human samples were used as matched controls. The formalin fixed samples were deparaffinized and digested with proteinase K. Genotyping was performed by PCR amplification, and in case of head and neck cancer a PCR-RFLP method was applied. No significant difference was found between tumor patients and controls in the investigated polymorphisms. A significant difference in survival was found between the GSTM1 and p53 gene variants in Dukes'B stage colorectal patients. The survival difference among the XRCC1 194 alleles by head and neck patients in clinical stage III proved to be also significant. The complex analysis of this type of genetic variants may be the future way of the personal risk assessment and the real chance for personal therapy.

Glutathione S-transferase P1 Ile105Val polymorphism and colorectal cancer risk: a meta-analysis and HuGE review

Colorectal cancer is the third most common form of cancer and the fourth most frequent cause of cancer deaths worldwide. Its development is influenced by both environmental and genetic factors. The glutathione S-transferase P1 gene (GSTP1) is a particularly attractive candidate for colorectal cancer susceptibility because it codes the enzyme involved in the metabolism of environmental carcinogens such as polycyclic aromatic hydrocarbons (PAHs). However, epidemiologic findings have been inconsistent. To investigate a putative association of GSTP1 Ile105Val polymorphism with the risk of colorectal cancer, we performed a meta-analysis and HuGE review of 16 published case-control studies (involving a total of 4386 colorectal cancer patients and 7127 controls). We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. Overall, the comparison of Val versus Ile allele showed no differential susceptibility to colorectal cancer (OR=0.98, 95% CI: 0.92-1.04). A protective effect was found in recessive, with an OR of 0.86 (95% CI: 0.76-0.98). Whereas no significant association was observed in either dominant or codominant model. In stratified subgroup analysis, no effect of Val allele was seen in subjects of Caucasian and Asian descent, and in healthy and hospital controls. In conclusion, the meta-analysis suggests that the GSTP1 Ile105Val polymorphism is unlikely to increase considerably the risk of sporadic colorectal cancer, and it should be confirmed in further studies.

Role of xenobiotic-metabolizing enzyme gene polymorphisms and interactions with environmental factors in susceptibility to gastric cancer in Kashmir Valley

BACKGROUND

Kashmir Valley has elevated incidence rate of gastric cancer (GC) and several environmental, host genetic factors have been suspected for it. Xenobiotic carcinogen exposure and interindividual differences in its cellular metabolism may modulate susceptibility to GC.

AIM OF THE STUDY

The aim of this study is to investigate the role of genetic variants of xenobiotic-metabolizing genes with susceptibility to GC in Kashmir Valley.

METHODS

A case-control study was performed in 303 subjects (108 GC and 195 healthy controls) to analyze the association of polymorphisms in GSTM1, GSTT1, GSTP1, GSTM3, CYP1A1, and CYP2E1 genes in susceptibility to GC in Kashmir Valley. All subjects were genotyped through polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

GSTM1null and CYP2E1c1c2 genotypes imparted risk for GC (odds ratio [OR] = 1.98, 95% confidence interval [95%CI] = 1.22-3.21, P = 0.006 and OR = 2.56, 95%CI = 1.25-5.25, P = 0.010, respectively). GSTM3AB genotype/B allele was found to be associated with low risk for GC. Smokers and high salted tea consumers themselves were at higher risk for GC (OR = 8.98, 95%CI = 5.16-15.62, P = 0.0001 and OR = 14.78, 95%CI = 8.02-27.23, P = 0.0001, respectively). Cancer risk was further enhanced in smokers with the GSTM1null genotype.

CONCLUSION

The results suggest that GSTM1null, GSTM3AB, and CYP2E1c1c2 genotypes modulate the risk of GC whereas GSTM1null genotypes enhance the risk of GC for smokers in the Kashmir population.

Association of GSTM3 intron 6 variant with cigarette smoking, tobacco chewing and alcohol as modifier factors for prostate cancer risk

Variations in glutathione-S-transferases (GSTs) genes may alter the catalytic efficiency of GST isoenzymes leading to potential increase in susceptibility to carcinogens present in cigarette smoke and tobacco. The present study aimed to explore the association of GSTM3 intron 6 polymorphism with susceptibility to prostate cancer (PCa), and to assess risks associated with cigarette smoking, tobacco chewing and alcohol consumption in PCa patients of North India. The study included 135 PCa patients and 169 controls. All subjects were genotyped for 3-bp deletion in intron 6 of GSTM3. Risk of developing prostate cancer associated with GSTM3 AB + BB was 2.5-fold (OR = 2.51, P = 0.028) as compared to AA genotype. Patients who were either smokers and/or had alcohol habits demonstrated a strong association with GSTM3 (AB + BB) genotype (OR = 4.11, P = 0.046; OR = 4.38, P = 0.027, respectively). Our results suggested GSTM3 (AB + BB) genotype to be significantly associated with PCa risk. The risk was even more apparent in case of cigarette smokers and alcohol consumers.

Polymorphism of glutathione S-transferase Omega gene: association with risk of childhood acute lymphoblastic leukemia

PURPOSE

To evaluate the association between glutathione S-transferase Omega (GSTO) genes polymorphism and the susceptibility of acute lymphoblast leukemia (ALL).

METHODS

The polymorphism of GSTO1 and GSTO2 genes were analyzed in 99 ALL patients compared with 100 healthy children by PCR-based restriction fragment length polymorphism (RFLP) analysis.

RESULTS

GSTO1*A140D polymorphism was significantly associated with susceptibility to ALL (OR = 2.24, 95% CI = 1.16-4.35, P = 0.009) whereas, GSTO2*N142D genotype was significantly interacted with high risk group of childhood ALL (OR = 5.52, 95% CI = 1.72-17.71, P = 0.004).

CONCLUSION

This study revealed gene polymorphism in glutathione S-transferase Omega class may be a risk factor to the development of acute childhood lymphoblastic leukemia.

Genetic polymorphisms inGSTM1,GSTT1,GSTP1,GSTM3and the susceptibility to gallbladder cancer in North India

The glutathione S-transferase (GSTs) are polymorphic supergene family of detoxification enzymes that are involved in the metabolism of numerous potential carcinogens. Several allelic variants of polymorphic GSTs show impaired enzyme activity and are suspected to increase the susceptibility to various cancers. To find out the association of GST variants with risk of gallbladder cancer, the distribution of polymorphisms in the GST family of genes (GSTT1, GSTM1, GSTP1, and GSTM3) were studied in 106 cancer patients and 201 healthy controls. Genotypes were analysed by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP). The frequencies of GSTM1 null and GSTM3*BB genotypes did not differ between patients and controls. The overall frequency of GSTT1 null was lower in cases as compared with controls (p=0.003, Odds ratio (OR) = 0.2, 95% confidence interval (CI), 0.1-0.6). After sex stratification, the GSTT1 null frequency was reduced only in female patients (p=0.008, OR = 0.2, 95% CI = 0.1-0.6). However, the GSTP1, ile/val genotype and the val allele were significantly higher in cases than controls (p=0.013, OR = 1.9, 95% CI = 1.1-3.1; p=0.027, OR = 1.5, 95% CI = 1.0-2.1), respectively. To study gene-gene interactions, a combined risk of gallbladder cancer due to ile/val or val/val were calculated in combination with null alleles of GSTM1 and GSTT1 or the *B allele of GSTM3, but there was no enhancement of risk. Gallstones were present in 57.5% of patients with gallbladder cancer, but there were no significant differences between allelic/genotype frequencies of the studied GST genes polymorphisms between patients with or without gallstones. To best of our knowledge, this is the first paper showing ile/val genotypes and val allele of GSTP1 to be associated with higher risk of gallbladder cancer.

The influence of polymorphisms of glutathione S-transferases M1 and M3 on the development of human urothelial cancer

Cigarette smoking is the most important risk factor for development of transitional cell carcinoma of the urinary bladder. The effect of polymorphisms of glutathione S-transferases M1 (GSTM1) and M3 (GSTM3) on the influence of cigarette smoking on urinary bladder carcinogenesis was investigated. In total, 293 bladder cancer patients from hospitals in Dortmund and Wittenberg as well as 176 patients without any malignancy from a Department of Surgery from Dortmund were genotyped for GSTM1 and GSTM3 according to standard PCR/RFLP methods. Smoking habits were quantified by a standardized interview. The proportion of GSTM1 negative cases was 63% in the entire bladder cancer cases group compared to 50% in controls. The GSTM3*A/*A genotype was 76% in cancer cases versus 74% in controls. Smokers and ex-smokers were overrepresented in bladder cancer cases. A significant association between smoking status and GSTM1 or GSTM3 genotype was not detected. The elevated proportion of GSTM1 negative bladder cancer cases shows an effect of this polymorphic enzyme on development of bladder cancer. In contrast to other studies, an influence of GSTM1 on the risk due to cigarette smoking was not observed.

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.

Role of GSTM3 polymorphism in the risk of developing esophageal cancer

GSTM3 is involved in detoxification of carcinogens and may be important in modulating cancer susceptibility. GSTM3 genotype frequencies were determined in peripheral blood DNA of 149 esophageal cancer patients and 200 nonmalignant controls using the PCR followed by PAGE. Patients who were heterozygous carriers of GSTM3 AB genotype had an enhanced risk for developing esophageal cancer [odds ratio (OR), 2.1; 95% confidence interval (95% CI), 1.1-3.7; P = 0.01]. In males, the risk due to GSTM3 AB genotype increased further (OR, 3.4; 95% CI, 1.7-6.8; P = 0.000). Interaction of GSTM3 AB + BB and GSTM1 null genotypes marginally modulated risk (OR, 2.3; 95% CI, 1.1-3.7; P = 0.01). Association with histology (adenocarcinoma: OR, 3.4; 95% CI, 1.1-10.9; P = 0.03) and tumor site (middle third location: OR, 2.2; 95% CI, 1.1-4.4; P = 0.01; lower third location: OR, 2.6; 95% CI, 1.2-5.6; P = 0.01) was also documented. Our results suggest that GSTM3 polymorphism may influence esophageal cancer susceptibility, in particular modulating the risk for adenocarcinoma histology and tumors of the mid and lower third region.

Genetic polymorphisms in xenobiotic clearance genes and their influence on disease expression in hereditary nonpolyposis colorectal cancer patients

BACKGROUND

Hereditary nonpolyposis colorectal cancer (HNPCC) is associated with germ-line mutations in DNA mismatch repair genes. There is considerable variation in disease expression that cannot be explained by genotype/phenotype correlation, which is likely to be the result of polymorphic modifier genes. One candidate group of modifiers is the xenobiotic clearance enzyme genes that encode CYP1A1, GSTM1, GSTT1, GSTP1, and NAT2. Alterations in these xenobiotic clearance genes can potentially influence the host response to carcinogen exposure and thereby alter cancer risk. We have investigated eight polymorphisms in xenobiotic clearance genes to assess the effect on the risk of disease in mutation positive HNPCC patients.

METHODS

DNA samples from 220 mutation-positive HNPCC participants (86 Australian and 134 Polish) were genotyped for single nucleotide polymorphisms (SNP) in CYP1A1, GSTM1, GSTT1, GSTP1, and NAT2. The association between the SNPs and disease characteristics, disease expression and age of diagnosis of colorectal cancer (CRC), was tested with Pearson's chi(2) and Kaplan-Meier survival analysis.

RESULTS

The HNPCC population displays a significant difference in the genotype frequency distribution between CRC patients and unaffected mismatch repair gene mutation carriers for the CYP1A1 SNP where the CRC patients harbor more of the mutant genotype.

CONCLUSIONS

Evidence from this study is not conclusive, but our data suggest that the CYP1A1 influences disease expression in individuals with HNPCC.

N-Acetyltransferase (NAT) 2 acetylator status and age of tumour onset in patients with sporadic and familial, microsatellite stable (MSS) colorectal cancer

INTRODUCTION

N-Acetyltransferase (NAT) 2 is an important enzyme involved in the metabolism of different xenobiotics, including potential carcinogens. Allelic variants of the NAT2 gene are determined by a pattern of single nucleotide polymorphisms (SNPs) resulting in slow (SA), intermediate (IA) or rapid acetylator (RA) phenotypes and causing the individual differences in the NAT2 metabolic capacity. To clarify the potential modifying role of the NAT2 acetylator status in microsatellite stable (MSS) colorectal cancer (CRC), we studied 140 patients with sporadic CRC (group 1) and 69 patients with CRC who met at least one criterion of the revised Bethesda guidelines (group 2).

OBSERVATIONS

We did not observe any significant difference in the NAT2 acetylator status frequency between patients in both groups and 100 healthy controls (P=0.486). Regardless of a younger median age of tumour onset (AO) of 41 years in group 2 patients compared to 64 years in group 1 patients, no significant difference in AO was found between RA and SA status patients in both groups. The median AO in group 1 was 65 years in patients with RA and 63 years with SA status (P=0.065). The median AO in group 2 was 40 years in patients with RA and 42 years with SA status (P=0.814). Multivariate Cox regression analysis revealed that neither the NAT2 acetylator status (P=0.064 and 0.810, respectively) nor the gender (P=0.165 and 0.918, respectively) was a risk factor for the AO in both groups. These data do not support the hypothesis that the NAT2 acetylatorship acts as a modifying factor on the AO in sporadic and familial, microsatellite stable CRC.

Colorectal cancer and genetic polymorphisms of CYP1A1, GSTM1 and GSTT1: a case-control study in the Grampian region of Scotland

Cytochrome P-450 CYP1A1 is involved in the metabolism of polycyclic aromatic hydrocarbons (PAHs) that are derived from meat intake and tobacco smoking. Expression of the CYP1A1 gene is induced by compounds present in cruciferous vegetables. The glutathione S-transferases play a central role in the detoxification of carcinogens, including PAHs. We investigated the association between colorectal cancer and three variants (CYP1A1*2A, CYP1A1*2C, CYP1A1*4) of the CYP1A1 gene, and homozygosity for the null deletion of the GSTM1 and GSTT1 genes, and the joint effects of these genotypes and smoking, meat intake and intake of green leafy vegetables in a population-based study of 264 cases and 408 controls in Northeast Scotland. There was an inverse association with the CYP1A1*4 (m4) variant (OR 0.3, 95% CI 0.13-0.70). The OR for the CYP1A1*2C (m2) variant was 1.3 (95% CI 0.59-2.91), which is similar to a combined estimate for previous studies (OR 1.2, 95% CI 0.95-1.41). We observed no association with the CYP1A1*2A (m1) variant, or the GSTM1 and GSTT1 polymorphisms. Significant interactions between all 3 CYP1A1 variants and meat intake, and between the m1 and m2 variants and intake of green leafy vegetables, were observed. There was no evidence of interaction between CYP1A1 and smoking, and no evidence of interaction between the GSTM1 or GSTT1 polymorphisms and smoking, meat intake, green leafy vegetable intake, CYP1A1 variants or each other.

Glutathione S-transferases mu 1, theta 1, pi 1, alpha 1 and mu 3 genetic polymorphisms and the risk of colorectal and gastric cancers in humans

INTRODUCTION

Glutathione S-transferases (GSTs) are considered to be cancer susceptibility genes as they play a role in the detoxification of carcinogenic species. This study aimed to elucidate the influence of several GST polymorphisms on colorectal and gastric cancer risk.

PATIENTS AND METHODS

GST mu1 (GSTM1), theta1 (GSTT1), pi1 (GSTP1), alpha1 (GSTA1) and mu3 (GSTM3) genotypes were determined in 144 colorectal cancer patients, 98 gastric cancer patients and 329 healthy control individuals.

RESULTS

Colorectal cancer: the risk is greater for carriers of the GSTM1 null genotype (odds ratio [OR] = 1.91, 95% confidence interval [CI] = 1.25-2.91), for carriers of the GSTT1 null genotype (OR = 3.62, 95% CI = 2.34-5.62), and for simultaneous carriers of both GSTM1 and GSTT1 null genotypes (OR = 4.98, 95% CI = 2.77-9.00). Carriers of the GSTP1 104 Val/Val genotype are at a lower risk (OR = 0.31, 95% CI = 0.09-0.88). Among carriers of the GSTP1 Ile/Ile genotype, smoking increases the risk compared with nonsmoking (OR = 2.35, 95% CI = 1.11-4.99). Gastric cancer: the risk is greater for carriers of the GSTT1 null genotype (OR = 2.58, 95% CI = 1.53-4.36) and for simultaneous carriers of both GSTM1 and GSTT1 null genotypes (OR = 3.32, 95% CI = 1.62-6.77). Carriers of the GSTP1 104 Val/Val genotype are at a lower risk (OR = 0.20, 95% CI = 0.02-0.86).

DISCUSSION

The GSTT1 null genotype, particularly if it is associated with the GSTM1 null genotype, greatly increases the risk for colorectal and gastric cancers. The GSTP1 104 Val/Val genotype may protect from both malignant tumors.

CONCLUSION

This study indicates that GST polymorphisms, in particular the GSTM1/GSTT1 double-null haplotype, can be considered low-penetrance genes for gastrointestinal cancer.

GSTM1 and GSTT1 Polymorphisms, Cigarette Smoking, and Risk of Colon Cancer: A Population-based Case-control Study in North Carolina (United States)

Cigarette smoke is a risk factor for colon cancer, but the importance of dose and interaction with genetic susceptibility remain poorly understood. We used data from a population-based case control study, to examine the association between cigarette smoking and colon cancer in African Americans and whites, and colon cancer and polymorphisms in GSTM1 and GSTT1. A total of 554 cases of primary colon cancer and 874 controls were included in this analysis. We found no association between cigarette smoking (ever versus never) and colon cancer in African Americans (odds ratio (OR)=0.93, 95% confidence interval (CI)=0.65-1.33). In contrast, there was an increased risk of cigarette smoking in whites (OR=1.43, CI=1.05-1.94). There was a small increased risk of colon cancer for individuals with GSTM1 null (African Americans, OR=1.43, CI, 0.98-2.09; whites, OR=1.19, CI, 0.90-1.58) and a decreased risk of colon cancer for individuals with GSTT1 null (African Americans, OR=0.59, CI: 0.40-0.86; whites, OR=0.72, CI: 0.53-1.00). There were weak interactions between GSTT1 null and cigarette smoking in whites, and GSTM1 null genotype and cigarette smoking in African Americans. GSTT1 and GSTM1 polymorphisms may be weakly related to colon cancer risk and there may be racial differences in gene-smoking interactions.

Gene-gene, gene-environment & multiple interactions in colorectal cancer

This review comprehensively evaluates the influence of gene-gene, gene-environment and multiple interactions on the risk of colorectal cancer (CRC). Methods of studying these interactions and their limitations have been discussed herein. There is a need to develop biomarkers of exposure and of risk that are sensitive, specific, present in the pathway of the disease, and that have been clinically tested for routine use. The influence of inherited variation (polymorphism) in several genes has been discussed in this review; however, due to study limitations and confounders, it is difficult to conclude which ones are associated with the highest risk (either individually or in combination with environmental factors) to CRC. The majority of the sporadic cancer is believed to be due to modification of mutation risk by other genetic and/or environmental factors. Micronutrient deficiency may explain the association between low consumption of fruit/vegetables and CRC in human studies. Mitochondrial modulation by dietary factors influences the balance between cell renewal and death critical in colon mucosal homeostasis. Both genetic and epigenetic interactions are intricately dependent on each other, and collectively influence the process of colorectal tumorigenesis. The genetic and environmental interactions present a good prospect and a challenge for prevention strategies for CRC because they support the view that this highly prevalent cancer is preventable.

Polymorphisms in sulfotransferase 1A1 and glutathione S-transferase P1 genes in relation to colorectal cancer risk and patients' survival

AIM

To examine whether polymorphisms in SULT1A1 and GSTP1 genes contribute to colorectal cancer development and whether they are associated with clinicopathological variables are not well identified.

METHODS

We examined the genotypes of 125 colorectal cancer patients and 666 healthy controls in a Swedish population by using PCR-restriction fragment length polymorphism (RFLP).

RESULTS

SULT1A1 *2/*2 genotype (OR=2.49, 95%CI=1.48-4.19, P=0.0002) and *2 allele (OR=1.56, 95%CI=1.16-2.10, P=0.002) had an effect on colorectal cancer susceptibility, while GSTP1 genotype was without effect. However, GSTP1 G-type predicted a worse prognosis in the patients independently of gender, age, Dukes' stage, growth pattern, and differentiation (P=0.03).

CONCLUSION

Polymorphism in SULT1A1 may predispose to colorectal cancer and GSTP1 may be a biological indicator of prognosis in the patients.