Polymorphisms of glutathione-S-transferase M1, T1, P1 and the risk of prostate cancer: a case-control study

Genetic variants of antioxidant and xenobiotic metabolizing enzymes and their association with prostate cancer: A meta-analysis and functional in silico analysis

The development and progression of prostate cancer (PCa) depends on complex interactions between genetic, environmental and dietary factors that modulate the carcinogenesis process. Interactions between chemical exposures and genetic polymorphisms in genes encoding xenobiotic metabolizing enzymes (XME), antioxidant enzymes and DNA repair enzymes have been reported as the main drivers of cancer. Thus, a better understanding of the causal risk factors for PCa will provide avenues to identify men at increased risk and will contribute to develop effective detection and prevention methods. We performed a meta-analysis on 17,518 cases and 42,507 controls obtained from 42 studies to determine whether seven SNPs and one CNV pertaining to oxidative stress, xenobiotic detoxification and DNA repair enzymes are associated with the risk of PCa (GPX1 (rs1050450), XRCC1 (rs25487), PON1 (rs662), SOD2 (rs4880), CAT (rs1001179), GSTP1 (rs1695) and CNV GSTM1). A significant increased risk of PCa was found for SOD2 (rs4880) ORGG+GA vs. AA 1.08; 95%CI 1.01-1.15, CAT (rs1001179) ORTT vs. TC+CC 1.39; 95%CI 1.17-1.66, PON1 (rs662) ORCT vs. CC+TT 1.17; 95%CI 1.01-1.35, GSTP1 (rs1695) ORGG vs. GA+AA 1.20; 95%CI 1.05-1.38 and GSTM1 (dual null vs. functional genotype) ORN vs. NN1+NN2 1.34; 95%CI 1.10-1.64. The meta-analysis showed that the CNV GSTM1, and the SNPs GSTP1 (rs1695) and CAT (rs1001179) are strongly associated with a greater risk of PCa and, to a lesser extent, the genetic variants SOD2 (rs4880) and PON1 (rs662). Although several antioxidant enzymes and XME play an important role in the PCa development, other risk factors such as chemical exposures should also be considered to gain insight on PCa risk. The functional in silico analysis showed that the genetic variants studied had no clinical implication regarding malignancy, except for GPX1 (rs1050450) SNP.

Polymorphism of glutathione S-transferase in the population of Polish patients with carcinoma of the prostate

The aim of the study was frequency analysis of GSTM1, GSTT1, and GSTP1 polymorphisms of glutathione S-transferase in the group of patients with prostate cancer and in a control group of healthy individuals. Genomic DNA was isolated; molecular analysis of glutathione S-transferase M1 and T2 polymorphisms was performed using multiplex PCR and RFLP methods. The products of the PCR reaction were then visualized in agarose gel, and a statistical analysis of the results was performed. No statistically significant differences were found in the frequency of glutathione S-transferase polymorphisms between 66 patients with prostate cancer and the control group (64 healthy volunteers). The GSTM1 gene deletion was found in ca. 47% of patients with prostate cancer and in ca. 55% of the controls. The GSTT1 deletion was found in approximately 17% of patients and 14% of the controls. The distribution of GSTP1 Ile/Ile, Ile/Val, and Val/Val polymorphisms was ca. 51.5%, 39%, and 9% in the group of patients and 61%, 34%, and 5% in the control group, respectively. The results indicate that there is no relationship between glutathione S-transferase polymorphisms and prostate cancer in the study group, which is a novelty when compared with the previous work on the role of these genetic variants in the etiology of cancer.

GSTM1 and GSTT1 Polymorphisms and Susceptibility to Prostate Cancer: A Case-Control Study of the Algerian Population

Objective: Prostate cancer (PCa) is a major public health problem worldwide, with high morbidity and mortality levels. Advanced age, androgen stimulation, and ethnicity have been reported to be possible risk factors. It has been suggested that particular genetic polymorphisms in glutathione S-transferases (GST), xenobiotic-metabolising enzymes, could predispose to prostate cancer through heritable deficiency in detoxification of environmental carcinogens. Conflicts in the published results and the absence of similar in depth studies in Algeria prompted us to perform the present case-control study of GSTM1 and GSTT1 polymorphisms and their possible association with PCa in an Algerian population. Methods: We determined GSTM1 and GSTT1 genotypes for 49 histologically verified prostate cancer patients and in 41 age-matched healthy controls by multiplex polymerase chain reaction (PCR) using peripheral blood DNA samples. Result: While an association between the GSTM1 null genotype and PCa risk (OR= 3.69, 95% CI= 1.30-10.44; P = 0.01) was evident, the GSTT1 null genotype (OR= 0.92, 95% IC= 0.32-2.62; P = 0.49) appeared without influence. Furthermore, no statistically significant differences between the double null genotype and PCa is detected, also no statistically significant differences between smoking status and PCa is detected. Conclusion: The GSTM1 null genotype may increase individual susceptibility to prostate cancer. On the other hand, the null-activity genotype of GSTT1 did not appear to contribute to the risk of prostate cancer in our population.

Glutathione S-transferase M1 and T1 polymorphisms, and their interactions with smoking on risk of low birth weight: a meta-analysis

Background: Published data regarding the association between glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) gene polymorphisms and risk of low birth weight (LBW) remains inconclusive, and data on the interactions between the two gene polymorphisms and smoking for LBW susceptibility is lacking. To clarify these associations, a meta-analysis was conducted.Methods: A comprehensive literature search was conducted in multiple databases until 11 January 2018. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using fixed or random effects model.Results: Thirty-eight studies from 17 articles concerning maternal and neonatal GSTM1 and GSTT1 gene polymorphism with LBW risk were included in this meta-analysis, and nine studies from five articles provided data of maternal tobacco exposure status during pregnancy. Maternal GSTM1 null genotype was associated with increased LBW risk (OR = 1.27, 95% CI: 1.12-1.45). There was a nonsignificant but positive association (OR = 1.19, 95% CI: 0.97-1.46) between the maternal GSTT1 null genotype and the LBW risk in the overall analysis. There was a null association between neonatal GSTM1 or GSTT1 polymorphism and LBW risk. There were significant associations between the maternal GSTM1 null and GSTT1 null genotype and LBW risk (for the former, OR = 3.85, 95% CI: 1.68-8.81; for the later, OR = 1.88, 95% CI: 1.01-3.50) in individuals with active smoking, respectively.Conclusion: Maternal GSTM1 and GSTT1 null genotypes, but not neonatal genotypes, are suggested to increase LBW susceptibility, and there are interactions between active smoking and these polymorphisms in the development of LBW.

CYP1A1 and GSTP1 gene variations in breast cancer: a systematic review and case-control study

In first part of this study, a systematic review was designed to explore the involvement of CYP1A1 and GSTP1 genes in breast cancerogenesis. Based on systematic review, we designed a study to screen CYP1A1 and GSTP1 genes for mutation and their possible association with breast carcinogenesis. A total of 400 individuals were collected and analyzed by PCR-SSCP. After sequence analysis of coding region of CYP1A1 we identified eleven mutations in different exons of respective gene. Among these eleven mutations, ~3 folds increased breast cancer risk was found associated with Asp82Glu mutation (OR 2.99; 95% CI 1.26-7.09), with Ser83Thr mutation (OR 2.99; 95% CI 1.26-7.09) and with Glu86Ala mutation (OR 3.18; 95% CI 1.27-7.93) in cancer patients compared to controls. Furthermore, ~4 folds increase in breast cancer risk was found associated with Asp347Glu, Phe398Tyr and 5178delT mutations (OR 3.92; 95% CI 1.35-11.3) in patients compared to controls. The sequence analysis of GSTP1 resulted in identification of total five mutations. Among these five mutations, ~3 folds increase in breast cancer risk was observed associated with 1860G>A mutation, with 1861-1876delCAGCCCTCTGGAGTGG mutation (OR 2.70; 95% CI 1.10-6.62) and with 1861C>A mutation (OR 2.97; 95% CI 1.01-8.45) in cancer patients compared to controls. Furthermore, ~5 folds increase in breast cancer risk was associated with 1883G>T mutation (OR 4.75; 95% CI 1.46-15.3) and ~6 folds increase in breast cancer risk was found associated with Iso105Val mutation (OR 6.43; 95% CI 1.41-29.3) in cancer patients compared to controls. Our finding, based on systematic review and experimental data suggest that the polymorphic CYP1A1 and GSTP1 genes may contribute to risk of developing breast cancer.

GSTP1, GSTM1, and GSTT1 polymorphisms as predictors of response to chemotherapy in patients with breast cancer: a meta-analysis

Several studies have investigated the effects of polymorphisms in the GSTP1, GSTT1, and GSTM1 genes on responsiveness to chemotherapy in breast cancer, but the results have been inconsistent. The aim of this study was to determine the association between polymorphisms of GSTP1, GSTT1, and GSTM1 genes and response to chemotherapy in patients with breast cancer. The relevant studies were retrieved from PubMed, Embase, ISI Web of Knowledge, China National Knowledge Infrastructure, and Wanfang databases. The articles evaluating the correlations between response to chemotherapy and GSTP1, GSTT1, and GSTM1 polymorphisms in breast cancer patients were comprehensively reviewed. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated to measure the strength of the associations. These associations were assessed with the χ ² test in this meta-analysis. Subgroup analysis by chemotherapy protocol and ethnicity were conducted to explore the source of heterogeneity among studies. A total of 14 articles with 31 studies involving GSTP1, GSTT1, and GSTM1 polymorphisms with response to chemotherapy were identified in the final meta-analysis. In the overall analysis, a significant association of GSTM1-present/GSTM1-null polymorphism with responsiveness to chemotherapy was observed in breast cancer patients (OR 0.74, CI 0.60-0.92, P = 0.006), whereas the GSTT1-present/GSTT1-null and GSTP1rs1695 polymorphisms were not significantly associated with clinical response to chemotherapy. The subgroup analysis by chemotherapy protocol indicated that the patients who harboring GSTP1rs1695 AA or AG variant had a higher response rate to anthracycline-based chemotherapy than those carrying GSTP1rs1695 GG variant [AA vs. GG: OR 0.48, CI 0.29-0.80, P < 0.05; AA vs. AG: OR 0.60, CI 0.43-0.83, P < 0.05; A vs. G: OR 0.60, CI 0.47-0.77, P < 0.05; AA vs. (AG + GG): OR 0.56, CI 0.42-0.76, P < 0.05; (AA + AG) vs. GG: OR 0.57, CI 0.34-0.94, P < 0.05]. In addition, the heterogeneity existed among studies for GSTP1 polymorphism, while no obvious heterogeneity was detected for GSTT1 and GSTM1 polymorphisms. And the heterogeneity present in different studies, evaluating the association of GSTP1 polymorphism with response to anthracycline-based chemotherapy, disappeared in breast cancer patients after subgroup analysis by chemotherapy regimen was performed. In conclusion, this meta-analysis suggested that GSTP1rs1695 and GSTM1-present/GSTM1-null polymorphisms could be considered as reliable predictors of response to anthracycline-based chemotherapy in patients with breast cancer.

Evaluation of Glutathione-S-Transferase P1 Polymorphism and its Relation to Bone Mineral Density in Egyptian Children and Adolescents with Beta-Thalassemia Major

BACKGROUND

Osteoporosis is a major complication of beta thalassemia major (TM). Increased oxidative stress and its controlling genes were linked to osteoporosis. Ile105 Val variant is a functional polymorphism of Glutathione S-transferase P1 (GSTP1), with reduced anti-oxidative property. No data are available about this variant or its association with osteoporosis among thalassemia patients yet.

OBJECTIVES

To investigate Ile105Val polymorphism and its possible association with bone mineral density (BMD) values in a group of TM children.

METHODS

Thirty five TM children and 30 age and sex matched healthy controls were included. Liver and renal functions, serum ferritin, calcium, phosphorous, alkaline phosphatase and osteocalcin were assayed. BMD was determined by DXA with calculation of Z-scores at lumbar spine (LS) and femoral neck (FN). Height for age Z- score (HAZ) adjusted BMD Z-scores were calculated. GSTP1 Ile105Val polymorphism was studied by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The relative frequency of 105 Val allele was significantly higher in TM patients than the controls (p<0.0001). Significant association between genotype subgroups and BMD parameters was detected. Compared to wild homozygotes, polymorphic homozygotes had lower LS-BMD (p =0.029), LS-BMD Z -score (p=0.008 ), LS- BMD haz - Z-score (p=0.011), FN- BMD (p= 0.001), FN- BMD Z -score (p=0.02) and FN-BMD haz - Z-score (p=0.001). They exhibited higher osteocalcin levels compared to heterozygotes and wild homozygotes (p=0.012, p=0.013, respectively).

CONCLUSION

Ile105Val polymorphism was frequent among TM patients and could increase their susceptibility to reduced BMD. Large sample studies are required to confirm these findings.

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.

GSTM1 Gene Polymorphism is Implicated in Increased Susceptibility to Prostate Cancer in Caucasians and Asians

Published reports on the relationship between GSTM1 gene polymorphisms and prostate cancer risk are heterogeneous in their conclusions, and the significance of these polymorphisms is still debated. This meta-analysis was performed to attempt to combine comparable studies, thereby increasing sample size and statistical significance in order to obtain a better evaluation of the association between GSTM1 polymorphisms and prostate cancer risk. The association investigations were identified from PubMed, Cochrane Library, and China Biological Medicine Database on March 1, 2014. Forty-three reports were recruited into this meta-analysis that contained data from 6741 patients and 9053 controls. There was a marked association between the GSTM1 null genotype and prostate cancer risk in the overall population (odds ratio = 1.39, 95% confidence interval: 1.21-1.60, P <00001), caucasians (odds ratio = 1.48, 95% confidence interval: 1.23-1.79, P <0001) and Asians (odds ratio = 1.62, 95% confidence interval: 1.16-2.27, P = .005). However, the GSTM1 null genotype was not associated with prostate cancer risk in Africans (odds ratio = 0.77, 95% confidence interval: 0.53-1.13, P = 0.19) and African Americans (odds ratio = 1.00, 95% confidence interval: 0.69-1.45, P = 0.99). In conclusion, GSTM1 null genotype was a risk factor to predict the prostate cancer risk in the overall population, Caucasians, and Asians. Although compelling, limitations inherent to meta-analysis, study design of the individual studies, and most importantly, possible gene-gene and gene-environment interactions, as well as the potential involvement of glutathione S-transferases in multiple cellular processes make drawing definite conclusions difficult.

Human glutathione S-transferase polymorphisms associated with prostate cancer in the Brazilian population

OBJECTIVE

To evaluate the influence of polymorphisms in GSTA1, GSTM1, GSTT1, and GSTP1 in the risk of developing Prostate Cancer (PCa) in a population of Rio de Janeiro and compare the distribution of allele and genotype frequencies of the polymorphisms analyzed in the present study population with other regions in the country and different ethnic groups.

MATERIALS AND METHODS

We analyzed a sample of the Brazilian population, comprising 196 patients with PCa treated by the urology services of the Brazilian National Cancer Institute (INCA) and Mario Kroeff Hospital (HMK), and 208 male blood donors from the Clementino Fraga Filho Hospital, Federal University of Rio de Janeiro (UFRJ). The polymorphisms were determined in DNA, extracted from peripheral blood leucocytes using the Polymerase Chain Reaction and Restriction Fragment Length Polymorphism (PCR-RFLP).

RESULTS

Our results showed that the distribution of polymorphisms can vary significantly according to the Brazilian region and ethnic groups. The distribution of allele and genotype frequencies of the polymorphism GSTA1 was statistically different between cases and controls. Genotypes (A / B + B / B) were associated with protection (OR = 0.61, 95% CI = 0.40-0.92) for PCa in comparison to genotype A / A.

CONCLUSION

The distribution of genotype frequencies of the polymorphism GSTA1 was statistically different between the case and control groups (p = 0.023), and the presence of genotypes A / B and B / B suggests a protective role against the risk of PCa compared to genotype A / A. This is the first study that reports the genotypic frequency of this polymorphism and its association with PCa in a Brazilian population sample.

Genetic polymorphisms and gene-dosage effect in ovarian cancer risk and response to paclitaxel/cisplatin chemotherapy

Background

Ovarian malignancies are often diagnosed in advanced stage and at the same time resistance to treatment, both intrinsic and developed during treatment, is sometimes observed. These facts underscore the need for new markers of ovarian cancer risk, as well as markers of treatment effectiveness.

Methods

In this study we genotyped 225 ovarian cancer patients, 64 breast and ovarian cancer patients and 348 healthy controls. In total, 12 polymorphic variants and 2 deletions in PGR, ABCB1, ABCG2, GSTT1, GSTM1, GSTP1, ATM, TP53 and ATP7B genes were analyzed using ASA-PCR, RFLP-PCR, multiplex-PCR and sequencing.

Results

Ten genetic polymorphisms were significantly associated with the risk of developing ovarian carcinoma in at least one of the groups under study. Impact of PGR gene polymorphisms on ovarian cancer risk was specific only for the group of the BRCA1 mutation carriers (in presence of p.Val660Leu variant- OR 2,82; p = 0,010), which confirms the difference in modulation of ovarian cancer risk between sporadic and hereditary malignancies, including the breast-ovarian cancer group (as a cancer-prone group). The analyses showed also the importance of ATP7B gene in ovarian carcinogenesis, both studied variants of which significantly modulated the ovarian cancer risk in all groups excluding the group with BRCA1 mutation. Cumulative risk analysis revealed 3 unfavorable variants that increased significantly the risk of developing ovarian cancer (p.Ile1145 = ABCB1+ p.Asp1853Asn ATM+ p.Ser406Ala ATP7B- OR 7,47; p = 0,002) and significantly modified the progression free survival (PFS) of the patients, and also two favorable genotypes which protected against ovarian cancer (p.Arg952Lys ATP7B+ p.Arg72Pro TP53- OR 0,50; p = 0,008). PFS analysis for carriers of favorable versus unfavorable genotypes emphasized the impact of the regulation of cell cycle (p.Asp1853Asn ATM) and active transport of xenobiotics (p.Ser894Ala/Thr ABCB1) on the risk of disease progression (HR 3,81; p = 0,010) after paclitaxel/cisplatin chemotherapy.

Conclusions

The unfavorable genetic variants could facilitate carcinogenic process and once their carriers developed malignancy, their chances of survival were smaller. Our analyses also showed a strong gene-dosage effect with the decrease of progression-free survival for the carriers of two unfavorable genetic factors.

GSTT1 polymorphism and the risk of developing prostate cancer

A possible association between glutathione S-transferase theta 1 gene (GSTT1) polymorphism and the risk of developing prostate cancer is currently hotly debated, but evidence from various epidemiologic studies remains unclear. This investigation was performed to assess whether an association between GSTT1 polymorphism and prostate cancer risk exists by using meta-analysis to combine comparable studies, thereby increasing sample size and statistical significance, as well as to identify patterns in various studies. The association reports were identified from the PubMed database and the Cochrane Library on March 1, 2013, and data from eligible studies (from 1999-2012) were synthesized. Thirty-eight reports were included in this meta-analysis on the association of the null genotype of GSTT1 with prostate cancer risk. No solid association between the GSTT1 null genotype and prostate cancer risk could be established for the overall population (odds ratio = 1.11, 95% confidence interval: 0.97, 1.27; P = 0.13). However, the GSTT1 null genotype was distinctly associated with prostate cancer risk in Caucasians (odds ratio = 1.24, 95% confidence interval: 1.03, 1.48, P = 0.02). In conclusion, the GSTT1 null genotype is associated with prostate cancer risk in Caucasians, but not in the overall population.

Glutathione S-transferase T1 and M1 polymorphisms and risk of uterine cervical lesions in women from central Serbia

The aim of this study was to investigate the frequencies of GSTT1 and GSTM1 deletion polymorphisms in newly-diagnosed patients with uterine cervical lesions from central Serbia. Polymorphisms of GST genes were genotyped in 97 patients with cervical lesions and 50 healthy women using a multiplex polymerase chain reaction (PCR). The GSTM1 null genotype was significantly more prominent among the patients than in controls (74.2% vs 56.0%), the risk associated with lesions being almost 2.3-fold increased (OR=2.26, 95%CI=1.10-4.65, p=0.03) and 3.17-fold higher in patients above >45 years old (95%CI=1.02-9.79, p=0.04). The analysis of the two genotypes demonstrated that GSTM1 null genotype significantly increased risk only for low grade squamous intraepithelial lesion-LSIL (OR=2.81, 95%CI=1.03-7.68, p=0.04). GSTT1 null genotype or different genotype combinations were not found to be risk factors, irrespective to lesion stages, age or smoking. We found that the risk of cervical lesions might be significantly related to the GSTM1 null genotype, especially in women aged above 45 years. Furthermore, the GSTM1 polymorphism might have greater role in development of early stage lesions.

Distribution of genetic polymorphisms of genes encoding drug metabolizing enzymes & drug transporters - a review with Indian perspective

Phase I and II drug metabolizing enzymes (DME) and drug transporters are involved in the absorption, distribution, metabolism as well as elimination of many therapeutic agents, toxins and various pollutants. Presence of genetic polymorphisms in genes encoding these proteins has been associated with marked inter-individual variability in their activity that could result in variation in drug response, toxicity as well as in disease predisposition. The emergent field pharmacogenetics and pharmacogenomics (PGx) is a promising discipline, as it predicts disease risk, selection of proper medication with regard to response and toxicity, and appropriate drug dosage guidance based on an individual's genetic make-up. Consequently, genetic variations are essential to understand the ethnic differences in disease occurrence, development, prognosis, therapeutic response and toxicity. For that reason, it is necessary to establish the normative frequency of these genes in a particular population before unraveling the genotype-phenotype associations. Although a fair amount of allele frequency data are available in Indian populations, the existing pharmacogenetic data have not been compiled into a database. This review was intended to compile the normative frequency distribution of the variants of genes encoding DMEs (CYP450s, TPMT, GSTs, COMT, SULT1A1, NAT2 and UGTs) and transporter proteins (MDR1, OCT1 and SLCO1B1) with Indian perspective.

Association between GSTP1 CpG methylation and the early phase of lead exposure

CONTEXT

GSTP1 is induced by lead, and thus serves as a biomarker of lead exposure. Lead exposure changes DNA methylation status.

OBJECTIVE

We attempted to prove that the methylation of the GSTP1 promoter plays an important role in lead toxicity.

MATERIALS AND METHODS

We conducted a case-control study of 53 workers from a battery plant and 53 age and sex matched healthy volunteers to determine whether the methylation level of the GSTP1 promoter is associated with the risk of lead poisoning. We employed methylation-specific PCR (MSP) in cell models to determine the relationship between the GSTP1 methylation level and lead exposure.

RESULTS

We found no association between GSTP1 methylation and lead exposure. The difference in methylation frequencies between the exposure group and the controls was not statistically significant (p = 0.401), and individuals with the methylated GSTP1 gene was not associated with the risk of lead poisoning (adjusted OR = 1.36, 95% CI, 0.22-8.24).

CONCLUSION

This study suggests that GSTP1 methylation is not involved in the early phase of lead toxicity. Further studies should be performed to detect the association between GSTP1 methylation and the risk of lead poisoning in later phases.

GSTP1 Ile105Val polymorphism and prostate cancer risk: evidence from a meta-analysis

BACKGROUND

Glutathione S-transferase P1 (GSTP1) is thought to be involved in the detoxification of reactive carcinogen metabolites. Numerous epidemiological studies have evaluated the association of GSTP1 Ile105Val polymorphism with the risk of prostate cancer. However, the results remain inconclusive. To derive a more precise estimation, a meta-analysis was performed.

METHODOLOGY/PRINCIPAL FINDINGS

A comprehensive search was conducted to identify the eligible studies. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the relationship. The overall association was not significant (Val/Val vs. Ile/Ile OR = 1.06, 95% CI = 0.90-1.25, P = 0.50; Val/Val vs. Val/Ile+Ile/Ile: OR = 1.07, 95% CI = 0.91-1.25, P = 0.44). In subgroup analyses by ethnicity and prostate cancer grade, the similar results were observed. However, in stratified analysis by clinical stage, we found a significant association with low-stage prostate cancer (Val/Val vs. Ile/Ile: OR = 2.70, 95% CI = 1.73-4.22, P<0.001; Val/Val vs. Val/Ile+Ile/Ile: OR = 2.14, 95% CI = 1.38-3.33, P = 0.001). Moreover, there was no statistically significant evidence of multiplicative interactions neither between the GSTP1 Ile105Val polymorphism and GSTM1, nor between smoking status and GSTP1 on prostate cancer risk.

CONCLUSIONS

This meta-analysis showed that GSTP1 Ile105Val polymorphism might not be significantly associated with overall prostate cancer risk. Further stratified analyses showed a significant association with low-stage prostate cancer.

Genetic polymorphisms in glutathione S-transferases P1 (GSTP1) Ile105Val and prostate cancer risk: a systematic review and meta-analysis

Numerous epidemiological studies have evaluated the association between the glutathione S-transferases P1 (GSTP1) Ile105Val polymorphisms and prostate cancer (PCa) risk. However, these studies have yielded conflicting results. A comprehensive search was conducted through researching MEDLINE, PubMed, Web of Science, and EMBASE, and a total of 13 studies including 3,227 cases and 3,945 controls were identified. A meta-analysis was performed to obtain a summary of estimated odds ratios (ORs) and 95% confidence intervals (CIs) of GSTP1 polymorphisms for PCa, with attention to study quality and publication bias. The GSTP1 Ile158Val variant genotypes are less associated with increased risk of PCa for the homozygote model (Val/Val vs Ile/Ile: OR = 1.42; I(2) = 63.7%; 95% CI = 1.02-1.97) and the recessive model (OR = 1.41; I(2) = 45.5%; 95% CI = 1.10-1.80). However, no associations were detected for other genetic models. In the stratified analysis by ethnicity, significant associations between GSTP1 Ile105Val polymorphism and PCa risk were also found among Caucasians for Val/Val vs Ile/Ile comparison (OR = 1.22; I(2) = 0.0 %; 95 % CI = 1.02-1.47) and for the recessive model (OR = 1.26; I(2) = 0.0%; 95% CI = 1.06-1.49), while there were no associations found for other genetic models. However, no associations were found in Asians and African-Americans for all genetic models when stratified by ethnicity. In conclusion, our meta-analysis provides evidence that GSTP1 Ile105Val gene polymorphisms contributed to PCa susceptibility.

The GSTP1 105Val allele increases breast cancer risk and aggressiveness but enhances response to cyclophosphamide chemotherapy in North China

The glutathione-S-transferase (GST) family contributes to the inactivation of various toxic compounds formed as secondary metabolites during oxidative stress. GSTP1 accounts for the majority of the GST family enzymatic activity, and the activity of GSTP1 enzyme can be altered by the presence of the Ile105Val polymorphism. In this study, we examined the polymorphic frequency of GSTP1 Ile105Val genotype in 920 breast cancer patients and 783 healthy controls in women of North China. Results showed that GSTP1 105Val allele (Ile/Val and Val/Val) was associated with a higher breast cancer risk (OR = 1.38, 95% CI: 1.14–1.69; P = 0.001) and more aggressive tumors with histological grade III (OR = 1.15, 95% CI: 1.05–1.26; P = 0.001), lymph node metastases (OR = 2.35, 95% CI: 1.72–3.21; P < 0.001), as well as ER negative (OR = 1.77, 95% CI: 1.31–2.39; P < 0.001) than those carrying the Ile/Ile allele. However, the patients with the GSTP1 105Val genotype had a better disease free survival after cyclophosphamide (CTX)-based chemotherapy than those with Ile/Ile (HR = 0.77, 95% CI: 0.45–0.91; P < 0.001). Furthermore, in vitro cellular experiments demonstrated that breast cancer cells with the GSTP1 105Val allele were significantly more sensitive to CTX-induced proliferation inhibition. Thus, we conclude that the GSTP1 105Val allele increases breast cancer risk and aggressiveness and enhance response to CTX-based chemotherapy in women of North China. Detection of the GSTP1 Ile105Val genotype may help screen for high-risk populations and direct individualized therapy.

Association between the GSTP1 Ile105Val polymorphism and prostate cancer risk: a systematic review and meta-analysis

Many studies have reported the role of glutathione S-transferase P1 (GSTP1) Ile105Val polymorphism with prostate cancer (PCa) risk. However, these studies have yielded conflicting results. Hence, we performed this meta-analysis to investigate the association between GSTP1 Ile105Val polymorphism and PCa in different inheritance models. A total of 13 eligible studies were pooled into this meta-analysis. There was significant association between the GSTP1 Ile158Val variant genotypes and PCa for Ile/Ile vs Val/Val comparison [odds ratio (OR) =0.705; I (2) =63.7 %; 95 % confidence interval (95 % CI) = 0.508-0.977], Ile/Val vs Val/Val comparison (OR=0.736; I (2) =8.0 %; 95 % CI=0.613-0.883), and dominant model (OR=0.712; I (2) =45.5 %; 95 % CI=0.555-0.913). However, no associations were detected for other genetic models. In the stratified analysis by ethnicity, significant associations between GSTP1 Ile105Val polymorphism and PCa risk were also found among Caucasians (Ile/Ile vs Val/Val comparison OR=0.818, I (2) =0.0 %, 95 % CI=0.681-0.982; Ile/Val vs Val/Val comparison OR=0.779, I (2) =0.0 %, 95 % CI=0.651-0.933; and dominant model OR=0.794, I (2) =0.0 %, 95 % CI=0.670-0.941), while there were no associations found for other genetic models. However, no associations were found in Asians and African-Americans for all genetic models when stratified by ethnicity. In conclusion, our meta-analysis indicates that GSTP1 Ile105Val polymorphisms contributed to the PCa susceptibility. However, a study with the larger sample size is needed to further evaluate gene-environment interaction on GSTP1 Ile105Val polymorphisms and PCa risk.

Association of GSTT1 gene polymorphisms with the risk of prostate cancer: an updating meta-analysis

It has been demonstrated that the glutathione S-transferase (GST) superfamily helps remove carcinogens from the body and thus might be associated with prostate cancer risk. In recent years, GSTT1 polymorphism has been extensively studied as a potential prostate cancer risk factor; however, the results are inconsistent. To investigate the association between GSTT1 and prostate cancer, we conducted a meta-analysis of 33 studies with 6,697 prostate patients and 7,643 controls. For GSTM1 null versus present genotype, the random effects odds ratio was 0.98 (95 % confidence interval (CI) 0.83-1.16) based on a wide population. Subgroup analyses in the different ethnic groups and different controls were performed. The OR was 1.01 (95 % CI 0.86-1.19) in Caucasians, 1.01 (95 % CI 0.70-1.47) in Asians, and 0.77 (95 % CI 0.42-1.42) in Africans. The OR was 0.98 (95 % CI 0.82-1.16) in non-benign prostate hyperplasia (BPH) controls and 1.09 (95 % CI 0.66-1.79) in BPH controls. In conclusion, our present meta-analysis demonstrates that there is no association between GSTT1 polymorphism and prostate cancer, even in the sub-analysis concerning different races and control sources. The direction of further research should focus not only on the simple relationship of GSTT1 and prostate cancer but also on gene-environment interaction and distinctions of different GSTs.

GSTT1 null genotype is associated with an increased risk of prostate cancer in caucasians: a meta-analysis

BACKGROUND

Many studies have investigated the association between glutathione S-transferase T1 (GSTT1) null genotype and the risk of prostate cancer (PCa), but the impact of GSTT1 null genotype on PCa risk in Caucasians is still unclear owing to the inconsistency of such studies. The present study aimed to quantify the strength of association between GSTT1 null genotype and the risk of PCa in Caucasians.

METHODS

We searched the PubMed, Embase and Web of Science databases for studies assessing the association between GSTT1 null genotype and the risk of PCa in Caucasians. We estimated the summary odds ratio (OR) with the corresponding 95% confidence interval (95% CI) to assess the association.

RESULTS

16 case-control studies with 11,648 subjects were included in this meta-analysis. Meta-analysis of a total of 16 studies showed GSTT1 null genotype was significantly associated with an increased risk of PCa in Caucasians (random-effects OR 1.30, 95% CI 1.10-1.53, p = 0.002). After adjustment for heterogeneity, GSTT1 null genotype was still associated with an increased risk of PCa in Caucasians (fixed-effects OR 1.33, 95% CI 1.17-1.52, p < 0.001). The cumulative meta-analyses of all 16 studies showed a trend of more obvious association as information accumulated by year.

CONCLUSIONS

Meta-analysis of available data suggests the GSTT1 null genotype is significantly associated with an increased risk of PCa in Caucasians.

Significant association of Glutathione S-transferase T1 null genotype with prostate cancer risk: a meta-analysis of 26,393 subjects

Background

Recent studies on the association between Glutathione S-transferase T1 (GSTT1) polymorphism and risk of prostate cancer showed inconclusive results. To clarify this possible association, we conducted a meta-analysis of published studies.

Methods

Data were collected from the following electronic databases: Pubmed, Embase, and Chinese Biomedical Database (CBM). The odds ratio (OR) and its 95% confidence interval (95%CI) was used to assess the strength of the association. We summarized the data on the association between GSTT1 null genotype and risk of prostate cancer in the overall population, and performed subgroup analyses by ethnicity, adjusted ORs, and types of controls.

Results

Ultimately, a total of 43 studies with a total of 26,393 subjects (9,934 cases and 16,459 controls) were eligible for meta-analysis. Overall, there was a significant association between GSTT1 null genotype and increased risk of prostate cancer (OR = 1.14, 95%CI 1.01–1.29, P = 0.034). Meta-analysis of adjusted ORs also showed a significant association between GSTT1 null genotype and increased risk of prostate cancer (OR = 1.34, 95%CI 1.09–1.64, P = 0.006). Similar results were found in the subgroup analyses by ethnicity and types of controls.

Conclusion

This meta-analysis demonstrates that GSTT1 null genotype is associated with prostate cancer susceptibility, and GSTT1 null genotype contributes to increased risk of prostate cancer.

The role of p21 3'UTR gene polymorphism in the risk of prostate cancer: a pilot study

The cell cycle regulator p21 plays an important role in regulating critical cell activities including cell cycle control, DNA repair and apoptosis. Consequently, it may affect the efficacy of the response to DNA damage and tumor development. The aim of our study was to evaluate the frequencies of the p21 C70T polymorphism, the association between this genetic variant and smoking status, and the serum prostate-specific antigen (PSA) levels and Gleason score in 118 prostate cancer patients and 130 males routinely screened for prostate cancer in the Slovak population. Blood samples were collected from all individuals for DNA isolation, used for subsequent genotyping assays via PCR-RFLP methods. Overall, we did not observe any significant association between this polymorphism and prostate cancer risk. An analysis of the association between the p21 genotypes and smoking was then conducted. Among smokers, CC and CT genotypes were associated with a non‑significant increased risk (OR=1.48; 95% CI, 0.80-2.76 and OR=1.15; 95% CI, 0.27‑4.77, respectively; p>0.05) in comparison to non-smokers with the CC genotype. Patients with a CT genotype and serum PSA levels≥10 ng/ml had an 84% decrease in prostate cancer risk (OR=0.16; 95% CI, 0.03-0.75; p<0.05) compared to cases with serum PSA levels <10 ng/ml and the CC genotype. No significant association was detected between Gleason score and prostate cancer risk. Based on these results, we concluded that the p21 C70T polymorphism is associated with decreased risk of prostate cancer in Slovak men. To confirm these findings, a systematic approach is required to identify sequence variants in this and other related genes, and subsequently, to test for an association between such variants, smoking status and tumor-specific clinicopathological characteristics in large samples.

Genetic polymorphisms of GSTM1, GSTT1, and GSTP1 with prostate cancer risk: a meta-analysis of 57 studies

Background and Objectives

The GSTM1, GSTT1 and GSTP1 polymorphisms might be involved in inactivation of procarcinogens that contribute to the genesis and progression of cancers. However, studies investigating the association between GSTM1, GSTT1 or GSTP1 polymorphisms and prostate cancer (PCa) risk report conflicting results, therefore, we conducted a meta-analysis to re-examine the controversy.

Methods

Published literature from PubMed, Embase, Google Scholar and China National Knowledge Infrastructure (CNKI) were searched (updated to June 2, 2012). According to our inclusion criteria, studies that observed the association between GSTM1, GSTT1 or GSTP1 polymorphisms and PCa risk were included. The principal outcome measure was the odds ratio (OR) with 95% confidence interval (CI) for the risk of PCa associated with GSTM1, GSTT1 and GSTP1 polymorphisms.

Results

Fifty-seven studies involving 11313 cases and 12934 controls were recruited. The overall OR, which was 1.2854 (95% CI = 1.1405–1.4487), revealed a significant risk of PCa and GSTM1 null genotype, and the similar results were observed when stratified by ethnicity and control source. Further, the more important is that the present study first reported the high risks of PCa for people who with dual null genotype of GSTM1 and GSTT1 (OR = 1.4353, 95% CI = 1.0345–1.9913), or who with GSTT1 null genotype and GSTP1 A131G polymorphism (OR = 1.7335, 95% CI = 1.1067–2.7152). But no association was determined between GSTT1 null genotype (OR = 1.102, 95% CI = 0.9596–1.2655) or GSTP1 A131G polymorphism (OR = 1.0845, 95% CI = 0.96–1.2251) and the PCa risk.

Conclusions

Our meta-analysis suggested that the people with GSTM1 null genotype, with dual null genotype of GSTM1 and GSTT1, or with GSTT1 null genotype and GSTP1 A131G polymorphism are associated with high risks of PCa, but no association was found between GSTT1 null genotype or GSTP1 A131G polymorphism and the risk of PCa. Further rigorous analytical studies are highly expected to confirm our conclusions and assess gene-environment interactions with PCa risk.

Association of GSTM1 null allele with prostate cancer risk: evidence from 36 case-control studies

BACKGROUND

Glutathione S-transferase M1 (GSTM1) is thought to be involved in detoxifying several carcinogens and may play a vital role in tumorigenesis. Numerous studies have evaluated the association between GSTM1 null/present polymorphism and risk of prostate cancer (PCa). However, the results remain inconsistent. To derive a more precise estimation, we performed a meta-analysis.

METHODOLOGY/PRINCIPAL FINDINGS

A comprehensive search was conducted to identify all eligible case-control studies. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. The overall association was significant (OR = 1.28, 95% CI: 1.11-1.48, P = 0.001). Moreover, subgroup analyses showed GSTM1 null genotype significantly associated with PCa risk among Asians (OR = 1.35, 95% CI: 1.03-1.78, P = 0.03) but not among Caucasians (OR = 1.12, 95% CI: 0.96-1.31, P = 0.16). In addition, we did not find that smoking modified the genotype effect on the risk of PCa.

CONCLUSIONS/SIGNIFICANCE

The present meta-analysis suggested that GSTM1 null allele was a low-penetrant risk factor for PCa among Asians.

Genetic factors in the pathogenesis of gastroesophageal reflux disease

Multiple factors play a role in the pathogenesis of gastroesophageal reflux disease (GERD). Two landmark studies showing higher concordance of disease in monozygotic than dizygotic twin pairs suggested the role of host genetic factors in its pathogenesis. Recent studies have shown that genetic polymorphism in genes influencing host's inflammatory response, drug metabolism, cell cycle regulation, xenobiotic pathways, DNA repair, mutagenesis, esophageal sensory function and gene silencing are associated with risk of GERD and its sequelae-Barrett's esophagus and esophageal adenocarcinoma. However, more studies on larger sample size are needed before reaching a definite conclusion on the role of an individual gene.

Glutathione S-transferase gene polymorphisms (GSTM1, GSTT1, GSTP1) and prostate cancer: a case-control study in Tehran, Iran

We evaluated the relationship between polymorphisms in the glutathione S-transferases (GSTs) GSTM1, GSTT1 and GSTP1 genes and prostate cancer (PCa). PCR-restriction fragment length polymorphism assay was used to genotype the GSTM1, GSTT1, and GSTP1 polymorphisms in 168 PCa cases and 336 frequency matched controls. The GSTM1 null, and GSTT1 null genotypes were associated with an increased odds ratio (OR) for PCa (OR=3.28, 95% confidence interval (CI): 2.47-5.64; P=0.005, and OR=3.21, 95% CI: 2.52-5.64; P=0.005, respectively) (Pcorrected=0.0062). The frequency of GSTP1 Val/Val genotype was 14.3% in cases compared with 2.4% in controls, this polymorphism thus being associated with a significantly increased risk of PCa (OR=3.72, 95% CI: 1.67-5.65; P=0.002). The risk associated with the concurrent absence of both of the genes (OR=4.8, 95% CI: 2.34-6.78) was greater than the product of risk in men with either null (OR=1.52, 95% CI: 0.82-2.31) genotype combinations (P=0.001, Pcorrected=0.0045). The combination of GSTP1 Ile/Val or Val/Val polymorphism with the GSTT1 null and GSTM1 null type resulted in an OR of 6.21 (95% CI: 4.83-16.87) (P=0.0001, Pcorrected=0.0062). A higher frequency of the GSTM1 null genotype and GSTT1 null genotype was observed in patients with Gleason score >7, with an OR for GSTM1 null 4.67 (95% CI: 3.64-7.62; P=0.001) and with an OR for GSTT1 null 3.62 (95% CI: 2.31-5.74; P=0.004). The results obtained demonstrated that simultaneous presence of three potentially risk alleles (GSTM1 null, GSTT1 null and GSTP1 Val) lead to a significant OR increase for PCa.

Proteomic profiling of potential molecular targets of methyl-selenium compounds in the transgenic adenocarcinoma of mouse prostate model

Because the Selenium (Se) and Vitamin E Cancer Prevention Trial (SELECT) failed to show the efficacy of selenomethionine for prostate cancer prevention, there is a critical need to identify safe and efficacious Se forms for future trials. We have recently shown significant preventive benefit of methylseleninic acid (MSeA) and Se-methylselenocysteine (MSeC) in the transgenic adenocarcinoma mouse prostate (TRAMP) model by oral administration. The present work applied iTRAQ proteomic approach to profile protein changes of the TRAMP prostate and to characterize their modulation by MSeA and MSeC to identify their potential molecular targets. Dorsolateral prostates from wild-type mice at 18 weeks of age and TRAMP mice treated with water (control), MSeA, or MSeC (3 mg Se/kg) from 8 to 18 weeks of age were pooled (9-10 mice per group) and subjected to protein extraction, followed by protein denaturation, reduction, and alkylation. After tryptic digestion, the peptides were labeled with iTRAQ reagents, mixed together, and analyzed by two-dimensional liquid chromatography/tandem mass spectrometry. Of 342 proteins identified with >95% confidence, the expression of 75 proteins was significantly different between TRAMP and wild-type mice. MSeA mainly affected proteins related to prostate functional differentiation, androgen receptor signaling, protein (mis)folding, and endoplasmic reticulum-stress responses, whereas MSeC affected proteins involved in phase II detoxification or cytoprotection, and in stromal cells. Although MSeA and MSeC are presumed precursors of methylselenol and were equally effective against the TRAMP model, their distinct affected protein profiles suggest biological differences in their molecular targets outweigh similarities.