The glutathione S-transferase GSTP1 polymorphism: effects on susceptibility to oral/pharyngeal and laryngeal carcinomas

Influence of polymorphisms in VEGF, TNF-α, and GSTP1 genes on retinopathy of prematurity risk: a Meta-analysis

Purpose: To investigate the influence of polymorphisms in vascular endothelial growth factor (VEGF), tumor necrosis factor-α (TNF-α), and glutathione S-transferase Pi isoform (GSTP1) genes on retinopathy of prematurity (ROP) risk, we performed a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant meta-analysis.Methods: An exhaustive search was conducted in PubMed, Web of Science, and CNKI for genetic studies evaluating the relationship between VEGF (-460 T/C, +936 C/T, -634 G/C, and -2578 C/A), TNF-α (-308 G/A) and GSTP1 (Ile/Val) polymorphisms and ROP risk from inception until November 2019. Odds ratio (OR) with the 95% confidence interval (CI) were used for estimating combined effect size. The quality of the included studies was evaluated using the Newcastle-Ottawa Scale (NOS).Results: A total of 14 studies met the inclusion criteria. The meta-analyses revealed that VEGF - 460 T/C was associated with ROP risk in the allele model (C vs. T, OR = 0.83, 95% CI: 0.74-0.94, P_OR=0.004), homozygous gene model (CC vs. TT, OR = 0.70, 95% CI: 0.54-0.91, P_OR=0.008), dominant gene model (CC + TC vs. TT, OR = 0.80, 95% CI: 0.67-0.95, P_OR = 0.012), and recessive gene model (CC vs. TC + TT, OR = 0.74, 95% CI: 0.59-0.94, P_OR = 0.014). However, we did not find significant differences in the genotype and allele distribution of VEGF + 936 C/T, -634 G/C, -2578 C/A, TNF-α - 308 G/A and GSTP1 Ile/Val polymorphisms, between ROP and control group (p > .05).Conclusions: VEGF polymorphism -460 T/C was associated with a lower ROP risk. Further research is warranted to investigate haplotype effects of VEGF polymorphisms on the risk of ROP.

Multiple logistic regression analysis predicts cancer risk among tobacco usage with glutathione S-transferase p1 genotyping in patients with head and neck cancer

INTRODUCTION

Numerous studies have been investigated to understand the association between glutathione S-transferase P1 (GSTP1) polymorphism and risk of head and neck cancer (HNC) but yielded contradictory results, and no studies could confirm polymorphism in GSTP1 and that tobacco usage increases the risk of HNCs. Therefore, this study aimed to understand the association of GSTP1 Ile105Val polymorphism with or without tobacco usage in carcinogenesis and clinicopathological characteristics of patients with HNC.

MATERIALS AND METHODS

Binary logistic regression analysis was performed to predict HNC risk with tobacco use and GSTP1 genotyping. Five predictor variables such as gender, age, tobacco usage, familial, and GSTP1 genotypes were included in the model.

RESULTS

The results of the logistic regression analysis show that the full model which considered all the five independent variables together was statistically significant, log-likelihood = -111.820, and all slopes are zero: G = 74.297, degree of freedom (DF) = 5, P = 0.000. The strongest predictor in this model is tobacco usage (odds ratio = Z = -5.16, P = 0.000).

CONCLUSION

The study concludes that multiple logistic regression analysis model could predict the risk factors in case-control studies where control samples are compromised.

Modulators of Redox Metabolism in Head and Neck Cancer

SIGNIFICANCE

Head and neck squamous cell cancer (HNSCC) is a complex disease characterized by high genetic and metabolic heterogeneity. Radiation therapy (RT) alone or combined with systemic chemotherapy is widely used for treatment of HNSCC as definitive treatment or as adjuvant treatment after surgery. Antibodies against epidermal growth factor receptor are used in definitive or palliative treatment. Recent Advances: Emerging targeted therapies against other proteins of interest as well as programmed cell death protein 1 and programmed death-ligand 1 immunotherapies are being explored in clinical trials.

CRITICAL ISSUES

The disease heterogeneity, invasiveness, and resistance to standard of care RT or chemoradiation therapy continue to constitute significant roadblocks for treatment and patients' quality of life (QOL) despite improvements in treatment modality and the emergence of new therapies over the past two decades.

FUTURE DIRECTIONS

As reviewed here, alterations in redox metabolism occur at all stages of HNSCC management, providing opportunities for improved prevention, early detection, response to therapies, and QOL. Bioinformatics and computational systems biology approaches are key to integrate redox effects with multiomics data from cells and clinical specimens and to identify redox modifiers or modifiable target proteins to achieve improved clinical outcomes. Antioxid. Redox Signal.

Genotype and Phenotype of Glutathione-S-Transferase in Patients with Head and Neck Carcinoma

OBJECTIVE: Association of glutathione-S-transferase M1 (GSTM1) polymorphisms and cancer has been demonstrated. Possible underlying mechanisms and genotype-phenotype correlations are not adequately investigated. The aim of this study was to investigate the influence of the GSTM1-null-genotype on the level of GSTM enzyme concentration and on the enzyme activity of GST in patients with head and neck cancer (HNC).

METHODS: We investigated in 83 patients and 91 healthy controls the GSTM1 polymorphisms, GSTM1 protein concentration, GSTM1 protein in tumor tissues, and total GST enzyme activity.

RESULTS: Total GST enzyme activity was significantly lower in patients with HNC (208 ± 9 μmol/min1) than in controls (264 ± 11 μmol/min1, P < 0.0001) but did not depend on GSTM1-genotype ( P = 0.1). GSTM protein concentration in null-genotype patients (3.6 ± 2.5 μg/mL, mean ± SE) was significantly lower than in GSTM1 allele carriers (26.7 ± 9.6 μg/ml, P < 0.0001); GSTM protein expression did not depend on GSTM1-genotype ( P > 0.5).

CONCLUSION: GST enzyme activity in patients with HNC is suppressed, indicating impaired detoxification capacity of tobacco-smoke-related carcinogens. This suppression is not correlated with the GSTM1-genotype. (Otolaryngol Head Neck Surg 2004;130:718-25.)

CYP1A1 MspI polymorphism and the risk of oral squamous cell carcinoma: Evidence from a meta-analysis

Numerous case-control studies have investigated whether the CYP1A1 gene polymorphism is involved in the occurrence of oral squamous cell carcinoma (OSCC); however, the conclusions are inconsistent. In order to further explore the correlation and obtain a strong conclusion, a meta-analysis was performed to systematically assess the association between the CYP1A1 MspI polymorphism and risk of OSCC. In the present meta-analysis, the odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) were used to assess the association. The statistical analyses were performed with STATA 11.0 software. The heterogeneity was assessed by Q test and I²test. The final analysis included 10 studies of 1,505 cases and 1,967 controls. The overall results suggested that the CYP1A1 MspI polymorphism was significantly associated with an increased risk of OSCC (CC+TC vs. TT: OR, 1.31; 95% CI, 1.01-1.70; P=0.043; CC vs. TC+TT: OR, 2.38; 95% CI, 1.58-3.58; P<0.001; CC vs. TT: OR, 2.52; 95% CI, 1.60-3.96; P<0.001; and C vs. T: OR, 1.45; 95% CI, 1.15-1.83; P<0.001). In a stratified analysis by ethnicity, a statistically significant correlation existed in the Asian population, but not mixed-race and Caucasian populations. In conclusion, despite several limitations, the present meta-analysis established that the CYP1A1 MspI polymorphism may be a risk factor for OSCC, particularly among the Asian population.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL RELEVANCE

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

Meta-analyses of the effect of CYP1A1 and CYP2D6 polymorphisms on the risk of head and neck squamous cell carcinoma

BACKGROUND

CYP1A1 and CYP2D6 are important genes encoding enzymes involved in the metabolism of toxic chemicals and carcinogens. However, inconclusive results for the association between CYP1A1 and CYP2D6 polymorphisms and the risk of head and neck squamous cell carcinoma (HNSCC) have been reported. We conducted a meta-analysis to evaluate the association of CYP1A1 and CYP2D6 polymorphisms with the risk of HNSCC.

METHODS

A database search yielded 19 relevant studies. 3 polymorphisms were included in the meta-analysis: CYP1A1, CYP2D6*4 and CYP2D6*10. Random or fixed effect models were used in the analysis.

RESULTS

The CYP1A1 polymorphism was associated with HNSCC (for m1m1 vs. m1m2: odds ratio (OR) = 1.26, 95% confidence interval (CI) = 1.030-1.542, pheterogeneity = 0.025; for the recessive model: OR = 1.316, 95% CI = 1.065-1.625, pheterogeneity = 0.001). The analysis showed evidence for association between the CYP2D6*4 polymorphism and HNSCC in Asian populations; however, negative results were also observed in other models. A significant association was also observed between CYP2D6*10 polymorphism and HNSCC risk.

CONCLUSIONS

The current study demonstrates that the CYP1A1 and CYP2D6 polymorphisms are associated with susceptibility to both development and progression of HNSCC.

Maternal environmental exposure, infant GSTP1 polymorphism, and risk of isolated congenital heart disease

The GSTP1 gene, highly expressed early in fetal life, is the most abundant phase 2 xenobiotic metabolism enzyme in a human placenta. Fetal inherited GSTP1 Ile105Val polymorphism may modify the metabolism and excretion of xenobiotics from fetal tissue and increase the risk of congenital heart disease (CHD). This study aimed to analyze the joint effects of GSTP1 genetic polymorphism (Ile105Val) and maternal environmental exposure on CHD risk. Within a case-control design, a total of 190 children with CHD (104 boys age 4 ± 5.6 years) and 190 healthy children (114 newborn boys) were genotyped for the GSTP1 Ile105Val polymorphism. Mothers completed a structured questionnaire on the demographics as well as the preconceptional and lifestyle exposures. A higher frequency of mothers of children with CHD (38 %) reported a positive history of exposure to toxicants (occupational and environmental) than mothers of healthy children (23 %) (p = 0.0013). Logistic regression analysis showed that maternal occupational and environmental exposures increased the risk of CHD (odds ratio, 2.6; 95 % confidence interval, 1.6-4.2; p < 0.0001). No significant differences in Ile105Val genotype frequencies were observed between the children with CHD and the healthy children (p = 0.9). Furthermore, case-control analysis showed no evidence of significant interaction between the maternal exposures and GSTP1 polymorphism. Maternal exposure to toxicants increased the risk of children with CHD. However, fetal GSTP1 Ile105Val polymorphism did not increase the risk of CHD.

Unusual intronic variant in GSTP1 in head and neck cancer in Pakistan

In the present case control study mRNA expression of the GSTP1 gene, encoding a phase II enzyme that detoxifies via glutathione conjugation, was investigated using semiquantitative PCR followed by SSCP for 49 confirmed head and neck (HN) cancer and 49 control samples. It was found that GSTP1 was upregulated in significantly higher number of cancers (OR 4.2, 95% CI 1.2- 15.3). Grade wise correlation was also observed with more up regulation in patients with more advanced grades of HN carcinomas. We also found that 5 patients showed variation in mRNA with a larger product size than expected. Sequencing revealed insertion of an intronic segment between the 6th and 7th exon of the GSTP1 gene. Germline screening was performed showing mobility shifts which suggested mutation at the DNA level resulting in intronic portion retention. This study is of prime importance for drug design and treatment selection to overcome increased resistance of HN cancers to drugs due to alteration in the GSTP1 gene.

Association of GSTP1 Ile105Val polymorphism and risk of head and neck cancers: a meta-analysis of 28 case-control studies

BACKGROUND AND AIMS

The Glutathione S-transferase P1 (GSTP1) polymorphism have been considered a risk modifier for developing head and neck cancer (HNC) in many studies; however, the results of such studies are inconsistent. The aim of this study was to evaluate the possible association between the GSTP1 Ile105Val polymorphism and risk of HNC.

METHOD

We performed a search in the relevant electronic database and a meta-analysis based on 28 published case-control studies that included 6,404 cases and 6,523 controls. To take into account the possibility of heterogeneity across the studies, a Chi-square based I(2)-statistic test was performed. Crude pooled odds ratios (ORs) with 95% confidence intervals (CIs) were assessed using both fixed-effects and random-effects models.

RESULTS

The results of this meta-analysis showed that the GSTP1 Ile105Val polymorphism was not significantly associated with risk of HNC in the overall study population (pooled OR 1.00, 95% CI 0.92-1.09) or in subgroup analyses stratified by ethnicity, sample size, tumor site or publication year. Moreover, substantial evidence of heterogeneity among the studies was observed. Publication year was identified as the main cause of heterogeneity.

CONCLUSION

This meta-analysis does not support a significant association between the GSTP1 Ile105Val polymorphism and risk of HNC.

Expression patterns of carcinogen detoxifying genes (CYP1A1, GSTP1 & GSTT1) in HNC patients

Carcinogen detoxifying genes may be involved in pathogenesis of head and neck cancer (HNC). CYP1A1 is phase I enzyme that converts carcinogens into water soluble compounds which are easily excreted from body. GSTs constitute phase II detoxification enzymes that recognize these highly electrophilic compounds and detoxify them. Abnormal expression of these genes can potentially lead to cancer initiation. In present study, we analyzed protein expression of these genes in a total of 192 HNC patients and noncancerous healthy control serum samples screened for GSTs specific activity by ELISA. Furthermore, expression of these molecules was also determined in 49 HNC tissues/ adjacent control tissue by immunohistochemistry with specific antibodies. Mean serum GSTs specific activity was found to be 7.7 (+11.5)U/L in HNC patients and 11.4 (+7.5)U/L in controls. Significant decrease (P < 0.05) in GSTs specific activity was observed in HNC patients compared with controls (P < 0.001). Data for immunohistochemistry showed that CYP1A1 and GSTT1 was down expressed whereas GSTP1 was over expressed in HNC tissues compared with adjacent normal control tissues. Results of immunohistochemistry revealed 63 % HNC tissues had weak, 27 % moderate and 10 % strong staining for CYP1A1. For GSTT1, 27 % HNC tissues had no staining, 49 % weak staining, 16 % moderate and 8 % strong staining. Similarly for GSTP1, percentages for weak, moderate and strong staining were 6 %, 12 % and 82 % respectively. These reduced proteins observed in cancer patients highlight a potential breach on DNA repair mechanism when compared with control. Thus altered expression of these detoxifying molecules may collectively contribute to HNC development in Pakistani population.

Cytochrome P450 1A1 Ile462Val polymorphism and oral carcinoma risk: an updated meta-analysis including 1,515 cases and 2,233 controls

Cytochrome P450 (CYP) 1A1 Ile462Val (exon7) polymorphism has been suggested to be a risk factor for several cancers. Published data on its association with oral cancer risk have generated conflicting results. Our previous meta-analysis containing data from prior to Jan 2008 regarding this issue failed to find a significant association between CYP1A1 Ile462Val variation and oral cancer susceptibility. An updated meta-analysis with eligible studies for the period up to May 2012 was conducted. Separate analyses on ethnicity and source of controls were also performed. A total of 13 case-control studies comprising 1,515 cases and 2,233 controls were lastly selected for analysis. Compared with the previous meta-analysis, the overall data also failed to indicate a significant association of CYP1A1 Ile462Val polymorphism with oral cancer risk (Val/Val vs. Ile/Ile--OR = 1.46; 95 % CI = 0.96-2.24; dominant model--OR = 1.01; 95 % CI = 0.81-1.25; and recessive model--OR = 1.46; 95 % CI = 0.96-2.23). However, in the subgroup analysis by ethnicity, increased cancer risk was observed among Asians under the additive and recessive models (Val/Val vs. Ile/Ile--OR = 1.74; 95 % CI = 1.04-2.90 and recessive model-OR = 1.73; 95 % CI = 1.04-2.87), inconsistent with the previous meta-analysis. Collectively, the data of the present study suggest that CYP1A1 variant Val/Val alleles might modify the susceptibility to oral cancer among Asians. Further well-designed investigations with large sample sizes are required to confirm this conclusion.

Association of CYP1A1, GSTM1, and GSTT1 gene polymorphism with risk of oral submucous fibrosis in a section of North Indian population

Genetic alterations in the genes expressing drug metabolizing enzymes can make an individual susceptible to various cancers. This study detects the polymorphisms at CYP1A1, GSTM1, and GSTT1 genes in a section of North Indian population and determines the susceptibility to oral submucous fibrosis (OSF). In this case-control study one hundred and two OSF patients were genotyped to detect the GSTM1, GSTT1, CYP1A1 polymorphism. Two hundred healthy controls were also included. Genotypes were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) approach. The frequency of GSTM1 and GSTT1 genotype was higher in OSF patients, as compared to controls. A trend risk analysis showed 7.6 fold increase in risk, when both the genes were absent. The frequency of CYP1A1 (m1) and CYP1A1 (m2) genotypes was higher in controls. No polymorphic alleles were detected in the m4 site. CYP1A1 (m1) wild genotype in the absence of GSTM1 null genotype, falls under the highest risk group (OR 3.74). Our findings suggest that CYP1A1 (m1) genotype and (m2) genotype singly acts as a protective factor but in the absence of GSTM1 and/or GSTT1 gene significantly alters risk towards OSF.

Polymorphisms of glutathione-S-transferase genes and the risk of aerodigestive tract cancers in the Northeast Indian population

BACKGROUND

Widespread use of tobacco and betel quid consumption and a high incidence of tobacco-associated aerodigestive tract cancers have been reported in different ethnic groups from several regions of Northeast (NE) India. This study was done to explore the possibility of phase II metabolic enzymes being responsible for the high prevalence of cancers in this region of India.

METHODS

Samples from 370 cases with oral, gastric, and lung cancers and 270 controls were analyzed for polymorphism of glutathione-S-transferase (GST) genes using polymerase chain reaction-restriction fragment length polymorphism-based methods.

RESULTS AND CONCLUSIONS

Tobacco smoking and betel quid chewing were found to be high risk factors for oral and lung cancers but not for gastric cancer, whereas tobacco chewing was found to be a risk factor for oral cancer but not for gastric or lung cancer. The variant genotypes of GSTP1 were not associated with any of the aerodigestive tract cancers. GSTT1 and GSTM1 null genotypes appeared to play a protective role for lung cancer (odds ratio [OR] = 0.47, 95% confidence interval [95% CI]: 0.24-0.93, p = 0.03) and (OR = 0.52, 95% CI: 0.28-0.96, p = 0.04), but they were not associated with oral and gastric cancers. However, when data was analyzed in different geographic regions the GSTT1 null genotype was found to be a significant risk factor for oral (OR = 2.58, 95% CI 1.01-6.61, p = 0.05) as well as gastric cancer (OR = 3.08, 95% CI 1.32-7.19, p = 0.009) in samples obtained from the Assam region of NE India. This is the first study on the association of GST polymorphisms and aerodigestive tract cancers in the high-risk region of NE India.

The expression of GST isoenzymes and p53 in non-small cell lung cancer

This study investigated the immunohistochemical staining characteristics of glutathione-S-transferase alpha, pi, mu, theta and p53 in non-small cell lung carcinoma and normal lung tissue from 50 patients. The relationships between expressions of the Glutathione-S-transferase isoenzymes and some clinicopathological features were also examined. Expression of glutathione-S-transferase pi, mu, alpha, theta and p53 was assessed by immunohistochemistry for primary lung carcinomas of 50 patients from the Sanitarium Education and Research Hospital, Ankara lung cancer collection. The relationships between expression of the glutathione-S-transferase isoenzymes, p53 in normal and tumor tissue by Student T test and the clinicopathological data were also examined by Spearman Rank tests. When the normal and tumor tissue of these cases were compared according to their staining intensity and percentage of positive staining, glutathione-S-transferase alpha, pi, mu, theta expressions in tumor cells was significantly higher than normal cells (p<0.05). There was no significant difference in the expression of p53 between normal and tumor cells (p>0.05). When the immunohistochemical results of glutathione-S-transferase isoenzymes and p53 were correlated with the clinical parameters, there were no significant associations between glutathione-S-transferases and p53 expressions and tumor stage, tumor grade and smoking status (p>0.05).

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.

Genetic polymorphism of glutathione S-transferases M1 and T1 in Egyptian patients with bilharzial bladder cancer

OBJECTIVE

To assess the influence of glutathione S-transferases M1 and T1 (GSTM1 and T1) genotype on the risk of bladder cancer in patients with urinary bilharziasis.

MATERIALS AND METHODS

This study was designed as a case-control study that involved 60 individuals who were enrolled into 3 equal groups. The first one included patients with bilharzial bladder cancer, the second one had those with nonmalignant urinary bilharziasis, and the last one was the control group. All of the participants were adult males, nonsmokers, and with matched ages. All of them underwent an assessment of the serum level of the total GST concentration and the polymerase chain reaction (PCR) was used for determination of the GSTM1 and T1 genotypes.

RESULTS

The lower most GST enzyme concentration was reported in patients with bilharzial bladder cancer (26 +/- 4.4 ng/ml) with significant difference between it and that of the second group (36.8 +/- 4.1 ng/ml, P < 0.05) and that of the controls (40.4 +/- 4 ng/ml, P < 0.005). The PCR results have demonstrated that the frequency of combined GSTM1 and T1 genes deletion (M1-ve T1-ve) was significantly higher in cases of bladder cancer (40%) than those of the controls (5%, P < 0.005) and those of the second group (10%, P < 0.05). The unconditional logistic regression test revealed that patients with urinary bilharziasis and combined GSTM1 and T1 genes deletion are at a significant risk for malignant transformation (OR = 6.3, P < 0.05).

CONCLUSIONS

Patients with urinary bilharziasis and GSTM1-ve and T1-ve genes might be at increased risk of bladder cancer. However, larger studies are needed for confirmation of these results.

Case-control study of oral and oropharyngeal cancer in whites and genetic variation in eight metabolic enzymes

BACKGROUND

Genetic variation in xenobiotic metabolizing enzymes may explain differing susceptibilities to the cancer causing effects of tobacco and alcohol.

METHODS

We compared 203 oral squamous cell carcinoma cases and 416 controls for single nucleotide polymorphisms (SNPs) in 8 genes (CYP1A1, CYP2E1, MPO, mEH, GSTM1, GSTT1, GSTP1, and NAT2). Except for NAT2, genotype frequencies were similar in the 2 groups. We classified subjects as fast or slow NAT2 acetylators genotyping 13 NAT2 SNPs.

RESULTS

Fast acetylators were overrepresented in cases (53.7%) compared with controls (43.9%; odds ratio (OR) 1.55, 95% confidence interval (CI) 1.08-2.20; p value = .03). Gene-gene interaction testing suggested several cancer-NAT2 associations, with association strongest among persons without a CYP1A1 variant (*2C or *4) allele (OR 1.77, 95% CI 1.20-2.60, p value = .03) or with a variant MPO (463A) allele (OR 2.38, 95% CI 1.34-4.21, p value = .05).

CONCLUSION

These results implicate fast NAT2 acetylation as a risk factor for oral cancer.

Meta-analysis and pooled analysis of GSTM1 and CYP1A1 polymorphisms and oral and pharyngeal cancers: a HuGE-GSEC review

The association of GSTM1 and CYP1A1 polymorphisms and oral and pharyngeal cancers was assessed through a meta-analysis of published case-control studies and a pooled analysis of both published and unpublished case-control studies from the Genetic Susceptibility to Environmental Carcinogens database (http://www.upci.upmc.edu/research/ccps/ccontrol/index.html ). Thirty publications used in the meta-analysis included a total of 7783 subjects (3177 cases and 4606 controls); 21 datasets, 9397 subjects (3130 cases and 6267 controls) were included in the pooled analysis. The GSTM1 deletion was 2-fold more likely to occur in African American and African cases than controls (odds ratio: 1.7, 95% confidence interval: 0.9-3.3), although this was not observed among whites (odds ratio: 1.0, 95% confidence interval: 0.9-1.1). The meta-analysis and pooled analysis showed a significant association between oral and pharyngeal cancer and the CYP1A1 MspI homozygous variant (meta-ORm2/m2: 1.9, 95% confidence interval: 1.4-2.7; Pooled ORm2m2: 2.0, 95% confidence interval: 1.3-3.1; ORm1m2 or [infi]m2m2: 1.3, 95% confidence interval: 1.1-1.6). The association was present for the CYP1A1 (exon 7) polymorphism (ORVal/Val: 2.2, 95% confidence interval: 1.1-4.5) in ever smokers. A joint effect was observed for GSTM1 homozygous deletion and the CYP1A1 m1m2 variant on cancer risk. Our findings suggest that tobacco use and genetic factors play a significant role in oral and pharyngeal cancer.

Association of genetic polymorphisms in glutathione S-transferases and susceptibility to head and neck cancer

Polymorphism in glutathione S-transferase (GST) genes (GSTM1, GSTT1 and GSTP1) and interaction with environmental factors such as tobacco (smoking or chewing) and alcohol on susceptibility to head and neck squamous cell carcinoma (HNSCC) was studied in a case-control study. The study group consisted of 175 patients suffering from HNSCC and 200 age matched healthy controls. Statistical analysis showed an increase in risk to HNSCC in the patients with null genotype of GSTM1 (OR: 2.02; 95% CI: 1.32-3.10; P=0.001) or GSTT1 (OR: 1.66; 95% CI: 1.02-2.69; P=0.04), though the risk was not found to be significant when adjusted for age, sex, smoking, tobacco chewing or alcohol use by multivariate logistic regression model. Our data further showed that combination of deletion genotypes of GST (GSTM1 and GSTT1) confer an even higher risk of HNSCC. Interestingly, GSTP1 wild type genotype in combination with GSTM1 null or GSTT1 null genotype increased susceptibility for HNSCC (OR: 2.49 and 2.75, respectively). Likewise a much greater risk for HNSCC was observed in the patients carrying a genotype combination of GSTM1 null, GSTT1 null and GSTP1 (Ile/Ile) (OR: 4.47; 95% CI: 1.62-12.31; P=0.002). Our data have further provided evidence that tobacco chewing and alcohol consumption are the important risk factors for HNSCC. The interaction between tobacco chewing and null genotype of GSTM1 or GSTT1 resulted in about 3.5- and 2.2-fold increase in the risk respectively in the patients when compared to those not chewing tobacco. Alcohol use resulted in more than 4-fold increase in the risk in the patients with null genotype of GSTM1 as compared to those who are non-drinkers. Alcohol consumption also increased the risk (approx. 3-fold) in the cases with null genotype of GSTT1, though the association was not found to be significant when compared to non-drinkers. Our data have provided evidence that GST polymorphism modifies the susceptibility to HNSCC and have further demonstrated importance of gene-environment interaction in modulating the risk to HNSCC.

Genetic polymorphisms of glutathione-S-transferase genes (GSTM1, GSTT1 and GSTP1) and upper aerodigestive tract cancer risk among smokers, tobacco chewers and alcoholics in an Indian population

The glutathione-S-transferase (GST) genes are involved in the detoxification of various carcinogens that increase the risk to upper aerodigestive tract (UADT) cancers. In the present study, 408 unrelated histopathologically confirmed cases and 220 population based controls, matched by age and gender, which belonged to the Tamilian population of south India were genotyped for polymorphisms in GSTM1, GSTT1 and GSTP1 using polymerase chain reaction (PCR) based methods. The multivariate logistic regression analyses demonstrated that GSTT1 null genotype was significantly associated with increased risk for UADT cancers (odds ratio (OR) 2.5; 95% confidence intervals (CIs) 1.3-4.7). The combined effects of GST genes have shown that concurrent lack of GSTM1 and GSTT1 had a significantly increased risk (OR 4.6; 95% CI 1.3-15.6), while GSTT1 null genotype along with GSTP1 polymorphic variants further increased the cancer risk (OR 5.3; 95% CI 2.0-13.6). The most remarkable risk was seen among individuals carrying GSTM1 null, GSTT1 null genotypes and GSTP1 polymorphic variants (OR 7.8; 95% CI 1.0-61.0). Tobacco chewers carrying GSTM1 null genotype had an enhanced risk for UADT cancers. An enhanced risk among tobacco chewers and alcoholics (regular) was noted in individuals with GSTT1 null genotype. Similarly, a significant interaction was observed among smokers (>40 pack-year (PY)) and tobacco chewers carrying GSTP1 mutant genotypes. Although the null genotype of GSTT1 is a strong predisposing risk factor for UADT cancers, we conclude that the significant gene-gene and gene-environment interactions of GST genes may confer a substantial risk to UADT cancers in the Tamilian population of south India.

Susceptibility to oral cancer by genetic polymorphisms at CYP1A1, GSTM1 and GSTT1 loci among Indians: tobacco exposure as a risk modulator

Oral cancer is the leading cancer type among Southeast Asian men and is causally associated with the use of tobacco. Genetic polymorphisms in xenobiotic-metabolizing enzymes modify the effect of environmental exposures, thereby playing a significant role in gene-environment interactions and hence contribute to the high degree of variance in individual susceptibility to cancer risk. This study investigates the role of polymorphisms at CYP1A1, GSTM1 and GSTT1 to oral squamous cell carcinoma (OSCC) in a case-control study involving 155 patients with precancerous lesions, 458 cancer patients and 729 age and habit-matched controls. Genotypes at these loci were determined by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism performed on genomic DNA extracted from peripheral blood lymphocytes. Risk to oral cancer was estimated among different tobacco exposure groups and doses using logistic regression analysis. GSTM1 null genotype conferred 1.29-fold increased risk [95% confidence interval (CI), 1.04-1.65] to OSCC. GSTT1 null genotype, however, conferred 0.57 times reduced risk to OSCC (95% CI, 0.39-0.83), specifically among tobacco chewers (odds ratio 0.27; 95% CI, 0.14-0.53). This risk was further reduced to 0.13 times (95% CI, 0.04-0.46) with increase in lifetime exposure to tobacco. We also investigated risk conferred by these genotypes at two different intra-oral sites, buccal mucosa and tongue. We found increased susceptibility to buccal mucosa cancer among individuals carrying these genetic markers. These results support the finding that GSTM1 null genotype is a risk factor to OSCC among Indian tobacco habits; GSTT1 null genotype, however, emerged as a protective factor.

Association of the GSTP1 and NQO1 polymorphisms and head and neck squamous cell carcinoma risk

The GSTP1 and NQO1 have been reported to be associated with an increased risk for smoking related head and neck squamous cell carcinoma (HNSCC). The purpose of this study was to determine the effect of these metabolic gene polymorphisms on the risk of HNSCC. The study population included 294 histologically confirmed HNSCC cases and 333 controls without cancer. Genotyping analysis of the GSTP1 Ile105Val and NQO1 Trp139Arg genes was performed by polymerase chain reaction-based techniques on DNA prepared from peripheral blood. The Mantel-Haenszel chi2 test was used for statistical analysis. The allele frequencies of the GSTP1 and NQO1 polymorphisms were not statistically significant between cases and controls. In analyzing the association between smoking amounts and genetic polymorphisms, GSTP1 and NQO1 polymorphisms were associated with cigarette smoking amounts in cases. G allele containing genotypes in GSTP1 and T allele containing genotypes in NQO1 were associated with a tobacco dose-dependent increase in risk of HNSCC and these genotype distributions were statistically significant (p<0.05). We found that the GSTP1 105Val allele and NQO1 139Arg allele were associated with tobacco dose-dependent increase in risk of HNSCC. GSTP1 and NQO1 genotype polymorphisms may play an important role in the development of smoking related HNSCC.

Glutathione S-transferase polymorphisms: cancer incidence and therapy

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

Association of GST genotypes with age of onset and lymph node metastasis in oral squamous cell carcinoma

BACKGROUND

Environment-gene interaction in oral carcinogenesis is well demonstrated by phase I and II enzymes that are involved in the metabolism of carcinogens. This study investigated the association of glutathione S-transferase (GST)T1 and GSTM1 genotypes of phase II enzyme genes with risk for, age of onset, and neck lymph node metastasis (LNM) in areca-associated oral squamous cell carcinoma (OSCC).

METHODS

A total of 114 OSCC male patients and 100 male controls were recruited. All subjects were areca users and tobacco smokers. DNA was obtained from peripheral blood samples. Genotyping of GSTT1 (non-null/null) and GSTM1 (non-null/null) was determined by polymerase chain reaction (PCR) analysis using specific primers that only amplify non-null alleles.

RESULTS

No association was found between GST genotype and the risk of OSCC based on case-controls. Patients with the GSTT1 null genotype were older at onset (P = 0.03). Those with the GSTM1 null genotype had a higher incidence of neck LNM than those with the GSTM1 non-null genotype (P = 0.01). Patients with the GSTM1/GSTT1 null genotype appeared to have later onset and a higher incidence of neck LNM than those carrying the opposite genotype.

CONCLUSION

The GST genotypes may be important markers for the age of onset and risk of metastasis in OSCC. The data also suggest that the various GST isoforms may be differentially involved in development or progression of OSCC.

Influential factors on tumor recurrence in head and neck cancer patients

Alcohol consumption and cigarette smoking play a key role in the development and progression of head and neck cancer. Additionally, epidemiologic studies have given evidence that other environmental and genetic factors are relevant. We present a prospective study including 465 head and neck cancer patients. All patients were recruited between 1994 and 1998 during the initial tumor diagnosis. Three hundred twelve patients could be followed over 5 years after histologically proven curative surgical treatment. All clinical data were recorded (i.e., age, gender, TNM stage, histological grading, smoking and drinking habits) and genetic variations at loci encoding detoxifying enzymes (glutathione S-transferase and cytochrome P450); immune modulating cytokines (tumor necrosis factor) and cell cycle regulating proteins (cyclin D1) were determined. Parameters with an impact on recurrence-free survival were analyzed. A strong influence could be attributed to the tumor size at the time of presentation. Additionally, the grading of the tumor showed a strong influence (5 years recurrence free: G1: 87% and G1: 61%). Furthermore, it could be shown that the recurrence-free survival was significantly influenced by cyclin D1 genotypes (CCND1GG: P =0.01; HR=3.72) and TNF microsatellite haplotypes (TNFB1D5: P =0.043; HR=2.05). These findings are compatible with the view that genetic predisposition is important in determining recurrence-free survival after surgical treatment of head and neck cancer.

Glutathione S-Transferase M1, T1, P1 Genotypes and Risk for Development of Colorectal Cancer

The glutathione S-transferase (GST) supergene family is an important part of cellular enzyme defense against endogenous and exogenous chemicals, many of which have carcinogenic potential. The present investigation was conducted to detect a possible association between polymorphisms at the GSTM1, GSTT1, and GSTP1 genes and the interaction with cigarette smoking and colorectal cancer incidence. We examined 181 patients with colorectal cancer and 204 controls. DNA was extracted from whole blood, and the GSTM1, GSTT1, and GSTP1 polymorphisms were determined using a real-time polymerase chain reaction and fluorescence resonance energy transfer with a Light-Cycler instrument. Associations between specific genotypes and the development of colorectal cancer were examined by use of logistic regression analysis to calculate odds ratios (OR) and 95% confidence intervals (CI). The GSTM1 polymorphism was associated with an increased risk of developing colorectal cancer (OR = 1.62, 95% CI: 1.06-2.46). Also the risk of colorectal cancer associated with the GSTT1 null genotype was 1.64 (95% CI: 1.10-2.59). Statistically no differences were found between patients with colorectal cancer and control groups for the GSTP1 Ile/Ile, Ile/Val and Val/Val genotypes. In addition, the frequencies of the GSTM1 and GSTT1 deletion genotypes differed significantly between the cases and controls for current smokers; the GSTT1 null genotype especially is associated with a greater risk of colorectal cancer (OR = 2.44, 95% CI: 1.24-4.81). The GSTM1 and GSTT1 deletions were associated with an increased risk of developing a transverse or rectal tumor (OR = 1.86, 95% CI: 1.15-3.00; OR = 1.70, 95% CI: 1.02-2.84; respectively). The glutathione S-transferase polymorphisms were not associated with risk in patients stratified by age. The risk of colorectal cancer increased as putative high-risk genotypes increased for the combined genotypes of GSTM1 null, GSTT1 null, and either GSTP1 valine heterozygosity or GSTP1 valine homozygosity (OR = 2.69, 95% CI: 1.02-7.11). In conclusion, the results obtained in this study clearly suggest that those susceptibility factors related to different GST polymorphic enzymes are predisposing for colorectal cancer.

Glutathione S-transferase M1, T1, and P1 gene polymorphism in laryngeal squamous cell carcinoma

PURPOSE

To investigate the influence of the glutathione S-transferase (GST) M1, T1, and P1 genotypes on the laryngeal squamous cell carcinoma risk.

MATERIAL AND METHODS

The study group consisted of 42 white patients with laryngeal squamous cell carcinoma (39 of them were male, mean age: 53, range: 37-67 and 3 of them were female, mean age: 47, range: 32-55) and 89 control subjects (nonsmokers = 47, smokers = 42) (58 male and 31 female, mean age: 51, range: 30-72). DNA samples were isolated from blood samples using high pure polymerase chain reaction (PCR) Template Preparation Kit. The detection of GST T1, GST M1, and P1 polymorphisms were detected by using real-time PCR.

RESULTS

Gene polymorphisms at GST M1 and P1 were not significantly different in patient and control groups. However, GST T1 null type significantly increased in laryngeal cancer patients when compared with the nonsmoking controls (P =.04).

CONCLUSIONS

There was a significant association between GST T1 null genotype and laryngeal squamous cell carcinoma. However the potential role of GSTs as markers of susceptibility to laryngeal carcinoma needs further studies in a larger number of patients.

Association of cytochrome P450 2E1 polymorphisms and head and neck squamous cell cancer

The development of head and neck squamous cell cancer (HNSCC) is known to be strongly associated with tobacco use. One of the main enzymes for bioactivation of tobacco-related substances is the cytochrome 450 (CYP)2E1, of which different genetic variants are described. Analyzing a correlation between certain neoplasia and alteration of the CYP2E1 gene, most studies focus on the polymorphisms -1053C>T and 7632T>A, but recently another polymorphism, named -71G>T, with enhanced transcriptional activity, has been identified. In the current case-control study we investigate the putative association of the mentioned CYP2E1 polymorphisms on the risk of HNSCC. Comparing 312 German individuals with HNSCC to 299 controls we found a significantly enhanced risk for the development of that neoplasia in smoking carriers of -71G>T heterozygosity, while in -1053C>T and 7632T>A polymorphisms a corresponding correlation was absent. Since a coincidence of an aberrant p53 gene and CYP2E1 mutations has been described, we choose a subgroup of 140 patients with HNSCC for analyzing an association of mutations in these two genes. However, no such association could be found in either of the mentioned polymorphisms. Further studies have to focus on the -71G>T polymorphism and its possible linkage to cancers, in which smoking is a known risk-factor, as well as its functional relevance concerning the bioactivation of tobacco-related substances.

Association between glutathione-S-transferase GSTP1 genotypes, GSTP1 over-expression, and outcome in epithelial ovarian cancer

Ovarian cancer accounts for the majority of deaths from gynaecological malignancy, and polymorphisms in genes encoding the glutathione-S-transferase (GST) GSTP1 detoxifying enzymes may lead to variation in detoxification of carcinogens. We describe a study involving 81 women with invasive epithelial ovarian cancer. A number of important clinical variables and outcome data were obtained. GSTP1 genotyping was undertaken using PCR-based techniques, and GSTP1 expression was quantified using immunohistochemistry (IHC). A Cox's proportional hazard regression model was used to analyze the effects on outcome. We also independently examined 11 women with borderline or low malignant potential (LMP) tumors using IHC only. The mean age of the women was 61.5 years +/- 12 (1 SD) (range 36-88 years), the median overall survival was 26 months, and median progression free interval (PFI) 21 months. There was a significant association between GSTP1 (Val(104)/Val(104)) genotypes, and reduced survival (P = 0.05) and the GTP1 (Ile(104)/Val(104)) genotype appeared to have the best outcome (HR = 0.34, P = 0.045, 95% CI = 0.12-0.98). There was no significant association between the GSTP1 genotypes and any clinico-pathological parameters; there were also no associations between GSTP1 genotypes and response to postoperative chemotherapy. Specific nuclear GSTP1 over-expression was associated with less residual disease (P = 0.05); specific cytoplasmic GSTP1 over-expression with more favourable performance status (P = 0.014)). We found that 10/11 (91%) of the LMP (borderline) tumors over-expressed nuclear GSTP1 compared to only 52% of the invasive tumors (chi(2) ((1)) = 5.95, P = 0.015). There was no significant association between the level of GSTP1 expression and response to postoperative chemotherapy. The overall level of GSTP1 expression and the subcellular localization of GSTP1 expression were not associated with either survival or PFI. There was a significant association between the GSTP1 (Ile(104)/Ile(104)) genotypes and increased overall GSTP1 expression (P = 0.049), and the GSTP1 (Ile(104)/Val(104)) genotypes and reduced overall GSTP1 expression (P = 0.046). We speculate that GSTP1 Ile(104)/Val(104) genotypes are associated with improved outcome because the protein/enzyme, which is expressed, may provide a better balance between the effects of detoxification of carcinogens and the effects of metabolism of chemotherapy agents. In addition, over-expression of nuclear GSTP1 appears to be associated with more favorable ovarian tumor characteristics. In our preliminary study, we also reported a relationship between overall GSTP1 expression and certain GSTP1 genotypes. As far as we are aware, this is the first time that a relationship between the GSTP1 genotypes, GSTP1 expression and outcome has been described in ovarian cancer. Whether the genotype directly determines GSTP1 expression is at present unclear and the precise mechanism of this interaction is unknown.

Polymorphisms of GSTT1 and related genes in head and neck cancer risk

BACKGROUND

Glutathione S-transferase T1 detoxifies some environmental carcinogens while activating others and is deleted in 15% to 38% of humans. We sought to determine whether GSTT1 genotype and genotypes of several related genes are associated with risk of squamous cell carcinoma of the head and neck (HNSCC).

METHODS

Somatic genotypes for GSTT1, GSTM1, GSTP1, and CYP1A1 were determined in 283 individuals with HNSCC and 208 population-based controls.

RESULTS

The OR for presence of GSTT1 was 1.6 (CI, 1.1-2.5, p = 0.03). HNSCC risk was not associated with GSTM1 null genotype, the presence of the GSTP1 Val/Val genotype, or the Val/Val homozygous genotype for CYP1A1. Stratified analysis revealed disparate ORs for women (OR, 3.0; CI, 1.5-6.3) and men (OR, 1.2; CI, 0.7-2.1) for the presence of GSTT1.

CONCLUSIONS

In this population, the presence of GSTT1 gene was associated with a significant increase in the risk of HNSCC. This association was particularly robust in women.

Outcomes of oral squamous cell carcinoma in Taiwan after surgical therapy: factors affecting survival

PURPOSE

The study goal was to determine which clinical features correlated with 5-year survival in patients surgically treated for oral squamous cell carcinoma (OSCC) in Taiwan.

PATIENTS AND METHODS

The records of 378 OSCC patients surgically treated with or without chemotherapy and radiotherapy were reviewed retrospectively. Their 5-year survival in relation to age, gender, tumor site, lymph node involvement, presence of distant metastasis, staging, differentiation, and risk factors, including betel quid (BQ) chewing, cigarette smoking, and alcohol consumption, was analyzed.

RESULTS

The majority of the patients were men (male-to-female ratio, 5.87:1) with the mean age of 57.1 +/-11.7 years. Tumors occurred mainly at the buccal mucosa (BM) (100 of 378, 26.5%), gingiva (105 of 378, 27.8%), and tongue (103 of 378, 27.2%). Neck nodal metastasis occurred frequently at the floor of the mouth (in >60% of cases), followed by the gingiva (45.7%), buccal mucosa (34%), and tongue (20.4%), whereas early distant metastasis was rare (5.3%). There were 104 (27.5%) stage 1, 96 (25.4%) stage 2, 98 (25.9%) stage 3, and 80 (21.2%) stage 4 patients. OSCC at the BM and gingiva was most (and at the tongue least) associated with risk factors of BQ use and smoking. The 5-year survival was 75%, 65.6%, 49%, and 30% for patients with stage I, II, III, and IV, respectively. The size, nodal involvement, distant metastasis, staging, differentiation, and BQ use significantly affected the survival (P <.05, Kaplan-Meier analysis). BQ use also correlated most significantly with the younger age of occurrence of OSCC patients.

CONCLUSIONS

Our data suggest that early treatment is the key to increasing the survival of OSCC patients. Periodic screening of high-risk populations for OSCC represents an urgent need in Taiwan.

GSTP1 A1578G (Ile105Val) polymorphism in benzidine-exposed workers: an association with cytological grading of exfoliated urothelial cells

A polymorphism at codon 105 (Ile/Val) in the GSTP1 gene has been associated with a higher risk for different cancer types. To assess the role of GSTP1 polymorphisms in the development of benzidine-related bladder cancer, GSTP1 AA, AG and GG genotypes were determined in occupationally benzidine-exposed Chinese workers without known disease and benzidine-exposed bladder cancer patients from the same cohort of the Shanghai area. An increased but not significant frequency of GSTP1 AG or GG carriers was observed in the occupationally exposed bladder cancer patient group [odds ratio (OR)=1.95, 95% confidence interval (CI) 0.70-5.46]. The odds ratios for the most important non-genetically determined risk factors for bladder cancer in male individuals were as follows: age (increase per year): OR 1.05, 95% CI 0.99-1.11; ever smoker: OR 1.31, 95% CI 0.47-3.69; duration of exposure (increase per year): OR 1.19, 95% CI 1.10-1.29; and high exposure: OR 4.50, 95% CI 0.70-5.46. Significant differences were found between all benzidine-exposed workers without known disease with modified exfoliated urothelial cells (grade II and higher) and all workers without known disease with at most minor changes (less than grade II) according to Papanicolaou (OR 1.90, 95% CI 1.13-3.20). These findings show for the first time an association between the GSTP1 AG or GG genotype and higher cytological gradings of exfoliated urothelial cells from formerly benzidine-exposed workers.

Prognostic potential of glutathione S-transferase M1 and T1 null genotypes for gastric cancer progression

To improve understanding of glutathione S-transferase (GST) behavior in terms of a development and prognostic factor for gastric adenocarcinoma, we investigated the association between the GSTM1 and GSTT1 null genotypes and gastric cancer risk or the prognostic value of the GSTM1 and GSTT1 null genotypes was evaluated. Using a polymerase chain reaction-based method, the frequencies of GSTM1 and GSTT1 genotypes and prognostic factors, such as staging, differentiation, and histologic type (intestinal vs. diffuse), were evaluated in 80 patients with curatively resected primary gastric adenocarcinoma. The frequencies of GSTM1 and GSTT1 null individuals were higher in the gastric cancer group, but the differences were not statistically significant (for GSTM1 null odds ratio (OR)=0.86; 95% confidence interval (CI)=0.49-1.51 and for GSTT1, OR=0.97; 95% CI=0.55-1.71). Since the GSTM1 and GSTT1 null genotypes are potential indicators of gastric adenocarcinoma, we examined the relationship between the GSTM1 and GSTT1 genotypes and prognostic factors. In terms of the histologically diffuse type of cancer, GSTM1 indicated an approximately 3.24-fold increase (OR=3.24; 95% CI=1.05-10.17). With respect to gastric cancer differentiation, the frequency of the GSTM1 null genotype was linked with a statistically significant increase in risk (3.42-fold) for the high-grade type (OR=3.42; CI=1.02-13.24). Our results indicate that there is no obvious relationship between GSTM1 and GSTT1 polymorphisms and the development of gastric cancer. However, in Korean gastric adenocarcinoma patients the GSTM1 null genotype appears to be associated with a poorer prognosis.

Glutathione S-transferase GSTP1 genotypes are associated with response to androgen ablation therapy in advanced prostate cancer

We determined whether the glutathione S-transferase GSTP1 Ile105 --> Val105 substitution is associated with response to androgen ablation therapy in patients with advanced prostate cancer. As response may be associated with tumor grade, Gleason score, clinical T stage and presence of metastases we also determined if GSTP1 genotypes were associated with these prognostic parameters. We speculated that GSTP1 Ile105/Ile105 would be linked with good response to androgen ablation therapy and, low/moderate tumor grade, 1/2 clinical T-stage, Gleason score < 6 and, no metastases. Genotype frequencies in cases and controls were not significantly different (P = 0.70) indicating that allelism in GSTP1 is not associated with susceptibility. There was no association between GSTP1 (Ile105/Ile105 versus Ile105/Val105 and Val105/Val105) and grade (P = 0.28, OR = 0.92), Gleason score (P = 0.84, OR = 0.94) or metastatic state (P = 0.68, OR = 0.88) though the frequency of GSTP1 Ile105/Ile105 was higher in cases with stage 1/2 tumors than those with stage 3/4 tumors (P = 0.03, OR = 1.89). GSTP1 Val105/Val105 was also associated with response to hormone ablation therapy. Thus, the GSTP1 Ile105/Ile105 frequency was significantly higher in 86/118 patients who demonstrated a good response than in those with poor response (P = 0.03, OR = 2.70). We speculate that the association of GSTP1 with response results from an effect of the gene product early in carcinogenesis.

GSTM1 enzyme concentration and enzyme activity in correlation to the genotype of detoxification enzymes in squamous cell carcinoma of the oral cavity

BACKGROUND

Differences in genotype and phenotype of detoxification genes could be one reason for conflicting results in studies dealing with gene polymorphisms as susceptibility factors for tobacco associated cancer.

OBJECTIVES

The objective of this study was to investigate gene polymorphisms of detoxification enzymes and to determine whether the enzyme concentration and activity of glutathione S transferase microliter 1 correlates with the genotype in patients with cancer of the oral cavity.

MATERIAL AND METHODS

In 73 cancer patients and 136 matched healthy controls, the polymorphisms of glutathione S-transferase mu1 and theta (GSTM/GSTT), cytochrome p450 1A1 and CYP2D6 were detected. Simultaneously, GSTM1 protein concentration and total GSTM1-activity were determined.

RESULTS

Only the coincidence of GSTM1 and GSTT null genotype was associated with oral cavity cancer. GSTM1 protein concentration and enzyme activity in null-genotype patients was significantly lower than in GSTM1-allele-carrier. But the enzyme concentration did not correlate with the activity.

CONCLUSION

We assume that detoxification enzymes are functionally redundant and that only the simultaneous deficiency of several detoxification enzymes increases the risk for oral cancer.

Polymorphisms of the glutathione S-transferase P1 gene and head and neck cancer susceptibility

BACKGROUND

Factors determining the individual susceptibility to head and neck squamous cell carcinoma (HNSCC) are still largely unknown. An imbalance between enzymes involved in the toxification and detoxification of (pre)-carcinogens closely related to HNSCC, which may appear during smoking and alcohol consumption, may play a role. Genetic polymorphisms in glutathione S-transferases (GSTs) often result in altered detoxification, which may contribute to individual susceptibility to HNSCC.

METHODS

We studied the frequencies of polymorphic variants in the GSTP1 gene in 235 patients with HNSCC and 285 healthy controls. In addition, data on exposure to alcohol and tobacco consumption were recorded. DNA was extracted from whole blood, and polymerase chain reaction-based methods were used to detect genetic polymorphisms.

RESULTS

In patients with HNSCC and control groups, the homozygous GSTP1 BB genotype was observed in 12.3% and 13.6%, respectively. No statistical differences were found for the GSTP1 AA and GSTP1 AB/GSTP1BB genotypes.

CONCLUSIONS

Our study showed that genetic polymorphisms of GSTP1 are not associated with altered susceptibility to HNSCC.