The investigation of GSTT1, GSTM1 and SOD polymorphism in bladder cancer patients

The structure-function relationships and physiological roles of MnSOD mutants

In this review, we focus on understanding the structure–function relationships of numerous manganese superoxide dismutase (MnSOD) mutants to investigate the role that various amino acids play to maintain enzyme quaternary structure or the active site structure, catalytic potential and metal homeostasis in MnSOD, which is essential to maintain enzyme activity. We also observe how polymorphisms of MnSOD are linked to pathologies and how post-translational modifications affect the antioxidant properties of MnSOD. Understanding how modified forms of MnSOD may act as tumor promoters or suppressors by altering the redox status in the body, ultimately aid in generating novel therapies that exploit the therapeutic potential of mutant MnSODs or pave the way for the development of synthetic SOD mimics.

50-bp insertion/deletion polymorphism of the superoxide dismutase-1 is associated with bladder cancer risk in an Iranian population

Bladder cancer (BC) is considered the sixth prevalent malignancy in men and the ninth leading cause of malignancy-related worldwide. Superoxide dismutase (SOD) is an antioxidant enzyme in the defense system against oxidative stress. Hence, we aimed to investigate whether the 50 bp Insertion/Deletion(Ins/Del) polymorphism of the SOD1 associated with the risk of BC. The study was conducted on 158 BC patients and 153 age-matched healthy subjects. Genomic DNA from all individuals was screened for the 50-bp SOD1 promoter deletion using PCR assay. Our results demonstrated an association between SOD1 Ins/Del (45% vs. 32%) genotype and risk of BC and this genotype elevated the susceptibility to BC (OR = 1.80, 95% CI: (1.10-2.90), P = 0.01). In addition, the Del allele of the SOD1 variation was detected to be more prevalent in the BC patients with the frequency of 28% and 20% in cases and healthy groups, correspondingly (OR = 1.61, 95% CI: (1.10-2.36), P = 0.01). It seems that SOD1 50-bp Ins/Del genotype, as well as Del, allele, is associated with an increased risk of BC in an Iranian population. However, further investigations in more diverse populations are necessary to assess the value of the novel biomarkers as a risk stratification biomarker for BC.

Association between SOD2 V16A variant and urological cancer risk

Background: The correlation between superoxide dismutase 2 (SOD2) V16A variant and urological cancer susceptibility has been widely studied, however, with divergent results.

Results: Totally, 9,910 cancer patients and 11,239 control subjects were enrolled. V16A variant is associated with an increased susceptibility to urological cancer (A-allele vs. V-allele: OR = 1.06, 95% CI = 1.00 – 1.13, P = 0.047; AA+AV vs. VV: OR = 1.09, 95% CI = 1.02 – 1.16, P = 0.008), especially for prostate cancer (PCa). Serum SOD2 level of PCa patients with VV+VA genotypes was lower than in those with AA genotypes. SOD2 expression is downregulated in both prostate and bladder cancer, as compared to the control. Furthermore, SOD2 was found to be downregulated in more advanced PCa participants, as compared to the ones in early stages. PCa subjects with low SOD2 expression displayed a shorter disease-free survival (DFS) time compared to that of the high SOD2 expression counterparts.

Conclusions: The SOD2 V16A variant may be associated with increased urological cancer susceptibility, especially for prostate cancer.

Methods: A pooled analysis utilizing odds ratios (ORs), in silico tools and ELISA was adopted to demonstrate this association. We also used immunohistochemical staining (IHS) to assess SOD2 expression.

Association of Glutathione S-transferase gene polymorphism with bladder Cancer susceptibility

BACKGROUND

We conducted a meta-analysis to evaluate the relationship between the glutathione S-transferase μ1 (GSTM1)- and glutathione S-transferase θ1 (GSTT1)- null genotypes and susceptibility to bladder cancer.

METHODS

We identified association reports from the databases of PubMed, Embase, the Cochrane Library and the China Biological Medicine Database (CBM disc) on July 1, 2017 and synthesized eligible investigations. Results were expressed using odds ratios (ORs) for dichotomous data, and we also calculated 95% confidence intervals (CIs).

RESULTS

In this meta-analysis, we found that the GSTM1-null genotype was associated with bladder cancer risk in the overall population, and individually in whites, Africans and Asians (overall population: OR = 1.40, 95% CI: 1.31-1.48, P<0.00001; whites: OR = 1.39, 95% CI: 1.26-1.54, P<0.00001; Africans: OR = 1.54, 95% CI: 1.16-2.05, P = 0.003; Asians: OR = 1.45, 95% CI: 1.33-1.59, P<0.00001). The GSTT1-null genotype was associated with bladder cancer risk in the overall population, but not in whites, in Africans or Asians (overall population: OR = 1.11, 95% CI: 1.01-1.22, P = 0.03; whites: OR = 1.16, 95% CI: 0.99-1.36, P = 0.07; Africans: OR = 1.07, 95% CI: 0.65-1.76, P = 0.79; Asians: OR = 1.05, 95% CI: 0.91-1.22, P = 0.51). Interestingly, a dual-null GSTM1-GSTT1 genotype was associated with bladder cancer risk in the overall population and in Asians (overall population: OR = 1.48, 95% CI: 1.15-1.92, P = 0.002; Asians: OR = 1.62, 95% CI: 1.15-2.28, P = 0.006). In conclusion, the GSTM1-null, GSTT1-null and dual-null GSTM1-GSTT1 genotypes might be associated with the onset of bladder cancer, but additional genetic-epidemiological studies should be conducted to explore this association further.

Association between MnSOD Val16Ala Polymorphism and Cancer Risk: Evidence from 33,098 Cases and 37,831 Controls

Manganese superoxide dismutase (MnSOD) plays a critical role in the defense against reactive oxygen species. The association between MnSOD Val16Ala polymorphism and cancer risk has been widely studied, but the results are contradictory. To obtain more precision on the association, we performed the current meta-analysis with 33,098 cases and 37,831 controls from 88 studies retrieved from PubMed, Embase, Chinese National Knowledge Infrastructure (CNKI), and Wanfang databases. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of association. We found that the polymorphism was associated with an increased overall cancer risk (homozygous: OR = 1.09, 95% CI = 1.00-1.19; heterozygous: OR = 1.07, 95% CI = 1.02-1.12; dominant: OR = 1.08, 95% CI = 1.02-1.14; and allele comparison: OR = 1.06, 95% CI = 1.02-1.11). Stratification analysis further showed an increased risk for prostate cancer, Asians, Caucasians, population-based studies, hospital-based studies, low quality and high quality studies. However, the increased risk for MnSOD Val16Ala polymorphism among Asians needs further validation based on the false-positive report probability (FPRP) test. To summarize, this meta-analysis suggests that the MnSOD Val16Ala polymorphism is associated with significantly increased cancer risk, which needs further validation in single large studies.

GSTM1 and GSTT1 polymorphisms are associated with increased bladder cancer risk: Evidence from updated meta-analysis

BACKGROUND

Previous studies have indicated association between GSTM1 and GSTT1 gene polymorphisms and bladder cancer susceptibility, but the results have been inconclusive. Here, we performed a meta-analysis to investigate the association between GSTM1/GSTT1 deletion polymorphisms and bladder cancer susceptibility.

METHODS

We searched for all studies investigating the association between GSTM1 or GSTT1 polymorphism and bladder cancer susceptibility in Pubmed, Web of Knowledge, and the Cochrane Central Search Library. A systematic review and meta-analysis were performed. Subgroup analyses were performed on different ethnicity, population-based and smoking status.

RESULTS

Our search identified 63 studies. GSTM1 null, GSTT1 null and GSTM1/GSTT1 double-null genotypes were associated with increased risk of bladder cancer (OR: 1.36 95% CI: 1.25-1.47, P<0.01; OR: 1.13 95% CI: 1.02-1.25, P<0.01; OR: 1.84 95% CI: 1.50-2.26, P<0.01). Subgroup analyses indicated that the GSTM1-null genotype was associated with increased risk of bladder cancer in Caucasians and Asians, while the GSTT1-null genotype was associated with increased risk of bladder cancer in Caucasians. The GSTM1/GSTT1 double-null genotype was associated with increased risk of bladder cancer in Caucasians, Asians, and Africans. Stratified analyses of population-based associations indicated increased bladder cancer risk associated with GSTM1-null and GSTM1/GSTT1 double-null genotypes in hospital-based and population-based studies. GSTM1 deletion was associated with increased bladder cancer risk in both smokers and nonsmokers. Non-smokers with the GSTM1/GSTT1 double-null genotype had an increased bladder cancer risk.

CONCLUSION

This meta-analysis demonstrates that the GSTM1-null, GSTT1-null, and GSTM1/GSTT1 double-null genotypes are associated with increased bladder cancer risk.

The relationship between GSTA1, GSTM1, GSTP1, and GSTT1 genetic polymorphisms and bladder cancer susceptibility: A meta-analysis

BACKGROUND

Previous studies have investigated the relationship between GSTA1, GSTM1, GSTP1, and GSTT1 polymorphisms and bladder cancer (BCa) susceptibility, respectively, but the results remain inconsistent. So, we conducted this meta-analysis including 79 case-control studies to explore such relationships.

METHODS

We searched PubMed, EMBASE, Cochrane library, Web of Science, and CNKI for relevant available studies. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were implemented to evaluate the intensity of associations. Publication bias was estimated using Begg funnel plots and Egger regression test. To assess the stability of the results, we used sensitivity analysis with the method of calculating the results again by omitting 1 single study each time. Between-study heterogeneity was tested using the I statistic.

RESULTS

No significant association between GSTA1 polymorphism and BCa susceptibility (OR = 1.05, 95% CI 0.83-1.33) was noted. Besides, meaningful association between individuals who carried the GSTM1 null genotype and increased BCa risk was detected (OR = 1.39, 95%CI 1.28-1.51). When stratified by ethnicity, significant difference was found in both Caucasian (OR = 1.39, 95% CI 1.23-1.58) and Asian populations (OR = 1.45, 95% CI 1.31-1.61). Moreover, in the subgroup analysis by source of controls (SOC), the results were significant in both hospital-based control groups (OR = 1.49, 95% CI 1.35-1.64) and population-based control groups (OR = 1.21, 95% CI = 1.07-1.37). Additionally, the analysis revealed no significant association between GSTP1 polymorphism and BCa risk (OR = 1.07, 95% CI 0.96-1.20). What is more, significant associations between GSTT1 polymorphism and BCa susceptibility were discovered (OR = 1.11, 95% CI 1.00-1.22). In the subgroup analysis by ethnicity, significant associations between GSTT1 null genotype and BCa risk were observed only in Caucasians (OR = 1.25, 95% CI 1.09-1.44). Furthermore, when stratified by SOC, no obvious relationship was found between the GSTT1 null genotype polymorphism with hospital-based population (OR = 1.11, 95% CI 0.97-1.28) or population-based population (OR = 1.10, 95% CI 0.96-1.27).

CONCLUSION

This study suggested that GSTM1 null genotype and GSTT1 null genotype might be related to higher BCa risk, respectively. However, no associations were observed between GSTA1 or GSTP1 polymorphisms and BCa susceptibility.

GSTT1 Null Genotype Significantly Increases the Susceptibility to Urinary System Cancer: Evidences from 63,876 Subjects

GSTT1 gene plays an important role in detoxification and clearance of reactive oxygen species(ROS). A null variant in this gene has been demonstrated to confer cancer susceptibility. Although many studies have demonstrated the association between GSTT1 null polymorphism and urinary system cancer susceptibility, several publications reported opposite conclusions. For better understanding the effects of this polymorphism on the risk of urinary system cancer, a updated meta-analysis was performed with a total of 26,666 cases and 37,210 controls extracted from 117 studies, by following the latest meta-analysis guidelines (PRISMA). The results suggested that the GSTT1 null genotype was significantly associated with an increased risk of urinary system cancer (OR=1.13, 95%CI=1.05-1.22). Furthermore, stratified analyses by the type of cancer, ethnicity, source of control and quality score presented a significantly increased risk associated with GSTT1 null genotype in bladder and prostate cancer subgroup, Caucasians and Indians subgroup, population-based(PB) subgroup, medium quality and low quality subgroup. Overall, our meta-analysis suggested that GSTT1 null genotype is a potential cancer susceptibility variant. Well-designed and large-cohort studies are needed to confirm the association between GSTT1 null genotype and urinary system cancer risk.

Pesticides, gene polymorphisms, and bladder cancer among Egyptian agricultural workers

This study examined the associations between pesticide exposure, genetic polymorphisms for

NAD(P)H

quinone oxidoreductase I (NQO1) and superoxide dismutase 2 (SOD2), and urinary bladder cancer risk among male agricultural workers in Egypt. Logistic regression was used to analyze data from a multicenter case-control study and estimate adjusted odds ratio (OR) and 95% confidence interval (CI). Exposure to pesticides was associated with increased bladder cancer risk (odds ratio (95% confidence interval): 1.68 (1.23-2.29)) in a dose-dependent manner. The association was slightly stronger for urothelial (1.79 (1.25-2.56)) than for squamous cell (1.55 (1.03-2.31)), and among participants with combined genotypes for low NQO1 and high SOD2 (2.14 (1.19-3.85)) activities as compared with those with high NQO1 and low SOD2 genotypes (1.53 (0.73-3.25)). In conclusion, among male agricultural workers in Egypt, pesticide exposure is associated with bladder cancer risk and possibly modulated by genetic polymorphism.

Polymorphisms of NRF2 and NRF2 target genes in urinary bladder cancer patients

PURPOSE

NRF2 transcription factor is involved in modulation of various antioxidant and metabolic genes and, therefore, may modulate anti-carcinogenic potential. Association between polymorphisms of NRF2 and five NRF2-regulated genes and urinary bladder cancer (BC) risk was analyzed.

METHODS

The study group included 244 BC patients, while the control group comprised 365 individuals with no evidence of malignancy. Genotyping of GSTM1 (deletion), GSTT1 (deletion), GSTA1 -69C/T (rs3957357), GSTP1 Ile105Val (rs1695), SOD2 Ala16Val (rs4880) and NRF2 -617C/A (rs6721961) in blood genomic DNA was performed by means of real-time PCR assays. The associations between gene polymorphism and BC risk were computed by logistic regression.

RESULTS

The frequency of GSTA1, GSTP1, SOD2 and NRF2 genotypes did not differ in both groups. A significantly higher BC risk was associated with GSTM1 null genotype after adjusting to age, sex and smoking habit (OR 1.85, 95 % CI 1.30-2.62; P = 0.001). GSTT1 null (OR 0.50, 95 % CI 0.31-0.81; P = 0.005) and GSTP1 Val105Val (OR 0.52, 95 % CI 0.27-0.98; P = 0.04) genotypes were associated with reduced BC risk separately or in combination (OR 0.24, 95 % CI 0.11-0.51; P < 0.0001) (P heterogeneity = 0.01). Combined GSTT1 null and SOD2 with at least one 16Val allele among never smokers encompass reduced BC risk (OR 0.14, 95 % CI 0.03-0.63; P = 0.01) (P heterogeneity = 0.04).

CONCLUSIONS

This study supports hypothesis that GSTM1 null genotype may be a moderate BC risk factor. The gene-gene and gene-environment interactions associated with combined GSTP1/GSTT1 and combined GSTT1/SOD2 genetic polymorphisms along with cigarette smoking habit may play a significant role in BC risk modulation.

Single-nucleotide polymorphisms of GPX1 and MnSOD and susceptibility to bladder cancer: a systematic review and meta-analysis

Reactive oxygen species-related damage plays a critical role in carcinogenesis. Glutathione peroxidase 1 (GPX1) and mitochondrial superoxide dismutase (MnSOD) are two key antioxidant enzymes in the defense system against reactive oxygen species. This systematic review and meta-analysis was designed to evaluate the association of single-nucleotide polymorphisms in GPX1 and MnSOD genes with susceptibility to bladder cancer risk. Online databases of PubMed, Embase, China National Knowledge Infrastructure, and SinoMed were searched to identify eligible studies. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated to estimated the association strength. The fixed effects model and random effects model were used to pool the data from different studies. By pooling all eligible studies, we found that the GPX1 Pro198Leu polymorphism was associated with a significantly increased risk of bladder cancer (Leu vs. Pro, OR = 2.111, 95% CI = 1.020-4.368, heterogeneity (p < 0.001); LeuPro/LeuLeu vs. ProPro, OR = 1.876, 95% CI = 1.011-3.480, heterogeneity (p < 0.001)). No significant association of MnSOD Ala-9Val polymorphism with cancer risk was observed (AlaVal/ValVal vs. AlaAla, OR = 0.966, 95% CI = 0.754-1.239, heterogeneity (p = 0.390); Vla vs. Ala, OR = 1.038, 95% CI = 0.782-1.377, heterogeneity (p = 0.015)). This systematic review and meta-analysis demonstrated that the GPX1 Pro198Leu polymorphism significantly increased susceptibility to bladder cancer, while the MnSOD Ala-9Val polymorphism was not associated with bladder cancer risk.

Glutathione S-transferase M1 polymorphism and bladder cancer risk: a meta-analysis involving 33 studies

Glutathione S-transferase M1 ( GSTM1) might be involved in inactivation of procarcinogens that contribute to the genesis and progression of cancers. GSTM1 null status has been extensively studied as a risk factor in bladder cancer susceptibility. The aim of this study is to evaluate the role of GSTM1 null genotype in bladder cancer risk. All available studies were considered in this meta-analysis, including 7301 cases and 9405 controls from 33 studies. Significantly increased risk was detected between GSTM1 deletion and bladder cancer susceptibility in all subjects (odds ratio [OR] = 1.409 [1.267–1.568], P < 0.001). The same patterns were observed in Caucasians (OR = 1.434 [1.212–1.697], P < 0.001) and Asians (OR = 1.485 [1.295–1.704], P < 0.001). When stratified with study design, a positive association was also found in hospital-based studies (OR = 1.552 [1.382–1.744], P < 0.001), but no association in population-based ones (OR = 1.088 [0.970–1.221], P = 0.151). In summary, our meta-analysis suggested that GSTM1 null status is associated with a high increase in the risk of bladder cancer, and further studies based on population design are necessary to confirm our conclusion.

Lipid peroxidation and antioxidant enzyme activities in cancerous bladder tissue and their relation with bacterial infection: a controlled clinical study

It is well known that antioxidants and reactive oxygen species play an important role in carcinogenesis. In this study, we attempted to evaluate antioxidant enzyme activities and lipid peroxidation levels in cancerous bladder tissue and to determine their relationship with bacterial infection. Bacterial culture was made from all urine samples using Blood and Eosin Methylene Blue agars for checking the presence of bacterial infections. We measured thiobarbituric acid reactive substances (TBARs) and activities of xanthine oxidase (XO), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and catalase (CAT) in cancerous tissues of 25 bladder cancer patients, in noncancerous adjacent bladder tissues of 13 out of these 25 patients, and in control bladder tissues of 15 patients with a non-neoplastic genitourinary disease. TBARs levels increased and XO, SOD, GSH-PX, and CAT activities decreased significantly in cancerous bladder tissues. TBARS, XO, and SOD levels were not significantly different between noncancerous adjacent tissue and control bladder tissue. Statistically significantly lower GSH-PX and higher CAT activities were observed in noncancerous adjacent bladder tissue compared with cancerous tissue. GSH-PX level of tumor tissue was correlated significantly with tumor grade (r=-0.425, P=0.034). Results suggested that pathway activity of free radicals were accelerated in the cancerous human bladder tissues via increased TBARs levels and decreased enzyme activities of XO, SOD, GSH-PX, and CAT, which implicated a severe exposure of cancerous tissues to oxidative stress.

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.

Genetic susceptibility to cancer: the role of polymorphisms in candidate genes

CONTEXT

Continuing advances in genotyping technologies and the inclusion of DNA collection in observational studies have resulted in an increasing number of genetic association studies.

OBJECTIVE

To evaluate the overall progress and contribution of candidate gene association studies to current understanding of the genetic susceptibility to cancer.

DATA SOURCES

We systematically examined the results of meta-analyses and pooled analyses for genetic polymorphisms and cancer risk published through March 2008.

STUDY SELECTION

We identified 161 meta-analyses and pooled analyses, encompassing 18 cancer sites and 99 genes. Analyses had to meet the following criteria: include at least 500 cases, have cancer risk as outcome, not be focused on HLA antigen genetic markers, and be published in English.

DATA EXTRACTION

Information on cancer site, gene name, variant, point estimate and 95% confidence interval (CI), allelic frequency, number of studies and cases, tests of study heterogeneity, and publication bias were extracted by 1 investigator and reviewed by other investigators.

RESULTS

These 161 analyses evaluated 344 gene-variant cancer associations and included on average 7.3 studies and 3551 cases (range, 508-19 729 cases) per investigated association. The summary odds ratio (OR) for 98 (28%) statistically significant associations (P value <.05) were further evaluated by estimating the false-positive report probability (FPRP) at a given prior probability and statistical power. At a prior probability level of 0.001 and statistical power to detect an OR of 1.5, 13 gene-variant cancer associations remained noteworthy (FPRP <0.2). Assuming a very low prior probability of 0.000001, similar to a probability assumed for a randomly selected single-nucleotide polymorphism in a genome-wide association study, and statistical power to detect an OR of 1.5, 4 associations were considered noteworthy as denoted by an FPRP value <0.2: GSTM1 null and bladder cancer (OR, 1.5; 95% CI, 1.3-1.6; P = 1.9 x 10(-14)), NAT2 slow acetylator and bladder cancer (OR, 1.46; 95% CI, 1.26-1.68; P = 2.5 x 10(-7)), MTHFR C677T and gastric cancer (OR, 1.52; 95% CI, 1.31-1.77; P = 4.9 x 10(-8)), and GSTM1 null and acute leukemia (OR, 1.20; 95% CI, 1.14-1.25; P = 8.6 x 10(-15)). When the OR used to determine statistical power was lowered to 1.2, 2 of the 4 noteworthy associations remained so: GSTM1 null with bladder cancer and acute leukemia.

CONCLUSION

In this review of candidate gene association studies, nearly one-third of gene-variant cancer associations were statistically significant, with variants in genes encoding for metabolizing enzymes among the most consistent and highly significant associations.