Genetic polymorphism of glutathione S-transferase T1 and the risk of colorectal cancer: A meta-analysis

Background: Studies investigating the association between genetic polymorphism of glutathione S-transferase T1 (GSTT1) and risk of colorectal cancer have reported conflicting results. In order to clarify the effect of GSTT1 polymorphism on the risk of developing colorectal cancer, we carried out a meta-analysis using published data to obtain more precise estimates of risk. Methods: Electronic searches of PubMed and EMBASE were conducted to select studies for this meta-analysis. Papers were included if they were observational studies investigating the association between GSTT1 polymorphism and colorectal cancer risk. The principal outcome measure was the odds ratio (OR) with 95% confidence interval (CI) for the risk of colorectal cancer associated with GSTT1 null genotype. Results: We identified 30 eligible studies, which included 7635 cases and 12,911 controls. The combined results based on all studies showed that there was a statistically significant link between GSTT1 null genotype and colorectal cancer risk (OR = 1.20, 95% CI = 1.03–1.40). In the analysis of ethnic groups, we observed distinct differences associated with GSTT1 null genotype, the pooled odds ratios for the GSTT1 polymorphism were 1.32 in Caucasians (95% CI = 1.09–1.58) and 1.03 in Asians (95% CI = 0.81–1.32). As far as concerned the interaction between GSTT1 genotype and colorectal cancer risk in relation to smoking history, there was no increase in risk for smokers or nonsmokers with the GSTT1 null genotype (smokers: OR = 1.13, 95% CI = 0.80–1.60, nonsmokers: OR = 0.99, 95% CI = 0.71–1.38). When stratifying by the location of colorectal cancer, we found that there was a statistically significant link in rectal cancer (OR = 1.50, 95% CI = 1.09–2.07), but not in colon cancer (OR = 1.33, 95% CI = 0.94–1.88). No associations could be detected between null GSTT1 polymorphism and age, sex, tumor stage and differentiation. Conclusion: Our current study demonstrates that GSTT1 null genotype is associated with an increased risk of colorectal cancer, specifically, among Caucasians.     

Glutathione S-transferase M1, T1, and P1 polymorphisms and thyroid cancer risk: A meta-analysis

Glutathione S-transferases (GSTs) genetic variants have been explored extensively as a predictive factor for cancer etiology. This meta-analysis aimed to examine the associations GSTM1, GSTT1, and GSTP1 genetic polymorphisms with thyroid cancer risk. PubMed, EMBASE, Cochrane Library, and HuGNet database were searched up to November 2011 using the appropriate terms. Twelve studies regarding GSTM1 null polymorphism (1569 cases and 2907 controls), 11 studies concerning GSTT1 null polymorphism (1515 cases and 2863 controls), and 8 studies on GSTP1 Ile105Val (965 cases and 1604 controls) were included in the meta-analysis. The random effects odds ratio was 1.07 (95% CI: 0.88–1.31; I² = 54.1%, P for heterogeneity = 0.013) for the GSTM1 null vs. present genotype and 1.08 (95% CI: 0.75–1.57; I² = 81.4%, P for heterogeneity < 0.001) for the GSTT1 null vs. present genotype, and 1.02 (95% CI: 0.70–1.49; I² = 74.6%, P for heterogeneity < 0.001) for the GSTP1 Val/Val + Val/Ile vs. Ile/Ile genotype. Similarly, no significant associations were demonstrated for subgroup analyses performed by ethnicity and histological type. In conclusion, these three polymorphisms are unlikely to be major determinants of susceptibility to thyroid cancer. Reasons for potential heterogeneity of effects, which could include true biologic heterogeneity, publication bias, or chance, deserve further investigation. The relationship between these three genes and thyroid carcinoma must be evaluated further with gene–gene and gene–environment interactions.     

CYP1AI, glutathione S-transferase gene polymorphisms and risk of Polycythemia vera

Background: Associations between polymorphisms for gene encoding enzymes involved in biotransformation of xenobiotics and susceptibility to several cancers have been shown in several studies. The aim of the present study was to evaluate the association of polymorphisms of cytochrome P450 (CYP1A1) and GST deletions with the incidence of Polycythemia vera (PV) among the Jordanian population. Methods: The study included 61 PV patients and 70 cancer-free healthy controls. CYP1A1 (m1, m2, m3, m4) and GST (T1, M1) genotypes were determined by polymerase chain reaction and restriction fragment length polymorphism. The risk of cancer associated with gene polymorphisms was estimated by calculations of odds ratio (ORs) and confidence intervals (95% CIs) using Mantel–Haenszel statistics. Results: A statistically significant difference between the PV group and the control group was observed in the case of GSTM1 null genotype with 3.38 fold increase in risk of developing PV (95% CI = 1.63–7.01, p = 0.001) while GSTT1 null genotype showed no significance (OR = 1.11; 95% CI = 0.50–2.44, p = 0.38). No significant association was found between the CYP1A1 mutant genotypes (m1, m2, m4) and PV. The m3 genotype was absent in both patients and controls. Interestingly, a substantial significant increase of PV risk for the combination of GSTM1 null genotype and CYP1A1 m1 (T6235C) genotype was observed (OR = 4.38; 95% CI = 1.15–16.73, p = .02). Furthermore, the present case–control study showed that the studied Jordanian population generally resembles Caucasian populations with respect to the frequencies of CYP1A1 polymorphisms. Conclusion: Our data suggests that GSTM1 null genotype alone and in combination with CYP1A1 m1 genotype may be predisposing risk factors for PV in the Jordanian population.     

A meta-analysis of the relationship between glutathione S-transferase T1 null/presence gene polymorphism and the risk of lung cancer including 31802 subjects

The relationship between glutathione S-transferase T1 (GSTT1) null/presence gene polymorphism and the risk of lung cancer from the published reports are still conflicting. This study was conducted to evaluate the relationship between GSTT1 null/presence gene polymorphism and the risk of lung cancer using meta-analysis method. The association studies were identified from PubMed, and Cochrane Library on July 1, 2012, and eligible investigations were included and synthesized using meta-analysis method. 51 reports were recruited into this meta-analysis for the association of null genotype of GSTT1 with lung cancer susceptibility, consisting of 15,140 patients with lung cancer and 16,662 controls. There was a marked association between GSTT1 null genotype and lung cancer risk in overall populations (OR = 1.15, 95 % CI 1.04–1.27, P = 0.007). Furthermore, GSTT1 null genotype was associated with the lung cancer risk in Asians (OR = 1.47, 95 % CI 1.23–1.76, P < 0.0001). However, GSTT1 null genotype was not associated with the risk of lung cancer in Caucasians, Brazilian population and Africans. In conclusion, GSTT1 null genotype is associated with the lung cancer in overall populations and in Asians.     

Ethnic differences in the association of the glutathione S-transferase T1 (GSTT1) null genotype and risk of gastric carcinoma: a systematic review and meta-analysis

We performed a systematic review and meta-analysis of the association between the glutathione S-transferase T1 (GSTT1) deletion polymorphism and gastric cancer risk in populations from different ethnic backgrounds, based on a comprehensive literature search of the MEDLINE, EMBASE, and COCHRANE libraries. Thirty-six individual case–control studies comprising 7,689 gastric cancer cases and 12,445 controls were included in our meta-analysis. Overall, the GSTT1 null genotype appeared to increase gastric cancer risk (OR 1.17, 95 % CI 1.06–1.31, p = 0.003). While Caucasian populations showed an association between the GSTT1 deletion polymorphism and gastric cancer risk (OR 1.27, 95 % CI 1.05–1.52, p = 0.01), Asian populations did not show such an association (p = 0.11). When stratified by quality assessment scores, a significant association between the GSTT1 deletion polymorphism and gastric cancer risk was observed only in the Caucasian high quality subgroup (OR 1.27 95 % CI 1.01–1.60, p = 0.05). Null genotypes for both GSTT1 and GSTM1 deletion polymorphisms also increased gastric cancer risk (OR 1.37, 95 % CI 1.04–1.80, p = 0.03). Our study suggests that the GSTT1 null genotype is associated with a significant increase in gastric cancer risk in Caucasians, but not in Asians. Further well-designed studies are required to confirm the association between GSTT1 polymorphisms and gastric cancer risk in relation to various clinicopathological factors in different ethnic groups, especially Caucasians.     

A meta-analysis of the relationship between glutathione S-transferases gene polymorphism and hepatocellular carcinoma in Asian population

The results from the published studies on the association between glutathione S-transferases (GST) gene polymorphism and hepatocellular carcinoma (HCC) in Asian population are still conflicting. GSTM1, GSTT1 and GSTP1 are the mainly mutant sites reported at present. This meta-analysis was performed to evaluate the relationship between GST gene polymorphism and HCC risk in Asians. Association studies were identified from the databases of PubMed, Embase, Cochrane Library and CBM-disc (China Biological Medicine Database) on February 1, 2012, and eligible investigations were synthesized using meta-analysis method. Results were expressed with odds ratios (OR) for dichotomous data, and 95?% confidence intervals (CI) were also calculated. Twenty-five investigations were identified for the analysis of association between polymorphic deletion of GSTM1 and HCC, consisting of 3,547 patients with HCC and 6,132 controls. There was a marked association between GSTM1 null genotype and HCC susceptibility (OR 1.48, 95?% CI 1.19–1.85, P?=?0.0004). GSTM1 null genotype was associated with HCC risk in Chinese. Furthermore, null genotype of GSTT1 was associated with HCC susceptibility in Asians. For the GSTM1–GSTT1 interaction analysis, the dual null genotype of GSTM1/GSTT1 was significantly associated with HCC susceptibility in Asian population. However, GSTP1 ile105?val gene polymorphism was not associated with HCC risk in Asian population. In conclusion, GSTM1/GSTT1 null genotype is associated with the HCC susceptibility. However, GSTP1 gene polymorphism is not associated with HCC risk.     

Polymorphisms of glutathione-S-transferase M1 and T1 and prostate cancer risk in a Tunisian population

Several genes involved in the metabolism of carcinogenesis have been found to be polymorphic in the human population, and specific alleles are associated with increase risk of cancer of various sites. This study is focused on the polymorphic enzymes glutathione-S-transferase M1 (GSTM1) and T1 (GSTT1) that involved in the detoxification of many xenobiotics involved in the etiology of prostate cancer. Objective. To evaluate whether GSTM1 and/or GSTT1 contribute to prostate cancer (CaP) etiology, we studied 110 incident CaP cases and 122 controls. Results. The probability of having CaP was increased in men who had homozygous deleted (non-functional) genotypes at GSTT1 (OR = 2.17; 95% CI = 1–3.79) but not GSTM1 (OR = 0.89; 95% CI = 0.66–1.88). Hence, individuals lacking the GSTT1 gene are at approximately twofold higher risk of developing prostate cancer in comparison with individuals with at least one active allele in the GSTT1 locus. Conclusion. These results suggest that GSTT1 is associated with CaP risk. The effect of smoking associated with the GSTT10/0 genotype was not found to affect the risk of prostate cancer.     

The Associations between Two Vital GSTs Genetic Polymorphisms and Lung Cancer Risk in the Chinese Population: Evidence from 71 Studies

Background

The genetic polymorphisms of glutathione S-transferase (GSTs) have been suspected to be related to the development of lung cancer while the current results are conflicting, especially in the Chinese population.

Methods

Data on genetic polymorphisms of glutathione S-transferase Mu 1 (GSTM1) from 68 studies, glutathione S-transferase theta 1 (GSTT1) from 17 studies and GSTM1-GSTT1 from 8 studies in the Chinese population were reanalyzed on their association with lung cancer risk. Odds ratios (OR) were pooled using forest plots. 9 subgroups were all or partly performed in the subgroup analyses. The Galbraith plot was used to identify the heterogeneous records. Potential publication biases were detected by Begg''s and Egger''s tests.

Results

71 eligible studies were identified after screening of 1608 articles. The increased association between two vital GSTs genetic polymorphisms and lung cancer risk was detected by random-effects model based on a comparable heterogeneity. Subgroup analysis showed a significant relationship between squamous carcinoma (SC), adenocarcinoma (AC) or small cell lung carcinoma (SCLC) and GSTM1 null genotype, as well as SC or AC and GSTT1 null genotype. Additionally, smokers with GSTM1 null genotype had a higher lung cancer risk than non-smokers. Our cumulative meta-analysis demonstrated a stable and reliable result of the relationship between GSTM1 null genotype and lung cancer risk. After the possible heterogeneous articles were omitted, the adjusted risk of GSTs and lung cancer susceptibility increased (fixed-effects model: OR_GSTM1 = 1.23, 95% CI: 1.19 to 1.27, P<0.001; OR_GSTT1 = 1.18, 95% CI: 1.10 to 1.26, P<0.001; OR_GSTM1-GSTT1 = 1.33, 95% CI: 1.10 to 1.61, P = 0.004).

Conclusions

An increased risk of lung cancer with GSTM1 and GSTT1 null genotype, especially with dual null genotype, was found in the Chinese population. In addition, special histopathological classification of lung cancers and a wide range of gene-environment and gene-gene interaction analysis should be taken into consideration in future studies.     

IκBα polymorphisms were associated with increased risk of gastric cancer in a southern Chinese population: a case-control study

AimNuclear factor-kappa B inhibitor alpha (IκBα) polymorphisms were found to be associated with inflammatory diseases. However, the association between IκBα polymorphisms with gastric cancer is still unknown. We aim to investigate the association between IκBα polymorphisms and gastric cancer risk in a large population-based case–control study among southern Chinese.Main methodsA population-based case–control study was conducted between 1999 and 2006 in Guangdong Province, China. A total of 1010 gastric cancer patients and 1500 healthy controls were enrolled in this study. IκBα polymorphisms were identified by sequencing of IκBα gene ranging from the 2 kb promoter region to the 3.5 kb genomic region. Polymorphisms in IκBα were analyzed by TaqMan SNP genotyping assay.Key findingsrs17103265 deletion homozygote (?/?) had significantly increased gastric cancer risk (OR = 2.11, 95% CI = 1.17–3.83, P = 0.01), compared with rs17103265 T homozygote (TT). rs17103265 (?/?) genotype was significantly associated with increased risk of intestinal-type gastric cancer with (OR = 2.21, 95% CI = 1.19–4.08, P = 0.01), but not with the diffuse or mix type of gastric cancer. rs17103265 (?/?) was associated with poorly differentiated gastric cancer (OR = 2.05, 95% CI = 1.07–3.94, P = 0.03), but not with moderately or well differentiated gastric cancer. A significant decrease in luciferase activity was observed in rs17103265 deletion allele as compared with the vector containing the rs17103265 T allele (P < 0.0001). rs17103265 polymorphism was not associated with the prognosis of gastric cancer patients.SignificanceIκBα rs17103265 deletion homozygote is a novel genetic risk factor for gastric carcinogenesis, especially for the development of certain subtypes of gastric cancer in southern Chinese population.     

Investigation of glutathione S-transferase M1 and T1 deletions in lung cancer

Glutathione S-transferases (GSTs) M1 and T1 are known to be polymorphic in humans. Both polymorphisms are due to gene deletions which are responsible for the existence of null genotypes. Previous studies have suggested that GST genotypes may play a role in determining susceptibility to a number of unrelated cancers, including lung cancer. The GSTM1 and GSTT1 polymorphisms were determined by PCR-based analysis in 75 lung cancer patients and 55 controls. The unconditional logistic regression analysis was used to calculate ORs and 95% CI. The frequencies of GSTM1 and GSTT1 null genotypes were 37.3 and 22.7% in lung cancer patients and 27.3 and 16.4% in controls, respectively. When analyzed by histology the GSTM1 null genotype was more prevalent in squamous-cell carcinoma and adenocarcinoma patients. Whereas, GSTT1 null genotype frequency was lower in small-cell lung cancer patients than controls. But these differences were not statistically significant. According to smoking status, null genotype for both gene are associated with an increase in risk for lung cancer. Our results suggest that GSTM1 and GSTT1 polymorphisms may play a role in the development of lung cancer for some histological subtypes and modifies the risk of smoking-related lung cancer.     

An updated meta-analysis on the association of TGF-β1 gene promoter -509C/T polymorphism with colorectal cancer risk

AimPublished data on the association between transforming growth factor-β1 (TGF-β1) gene promoter-509C/T polymorphism and colorectal cancer (CRC) risk are inconsistent and inconclusive. To derive a more precise estimation of this association, a meta-analysis was carried out.MethodsMeta-analysis was performed to evaluate reported studies of the relationship between TGF-β1 gene promoter-509C/T polymorphism and colorectal cancer risk using fixed-effects model and random-effects model.ResultsWe observed an increased colorectal cancer risk among subjects carrying TGF-β1 gene promoter-509CC + CT genotype (odds ratio (OR) = 1.18%, 95% confidence interval (95% CI): 1.06–1.32) using 4440/6785 cases/controls in total population. We observed an increased risk of the TGF-β1 gene promoter -509CC, CT and CC + CT polymorphisms for colorectal cancer in population-based study (OR = 1.36, 95% CI: 1.19–1.56, OR = 1.18, 95% CI: 1.03–1.34 and OR = 1.26, 95% CI: 1.12–1.43, respectively) in stratified analysis. We observed an increased colorectal risk among CC and CC + CT carriers in European and American population (OR = 1.22, 95% CI: 1.04–1.43 and OR = 1.18, 95% CI: 1.02–1.38, respectively). We also observed an increased risk of colon cancer among subjects carrying CC + CT genotype (OR = 1.31, 95% CI: 1.05–1.63).ConclusionsThe present meta-analysis results suggest that TGF-β1 gene promoter -509C allele variant is a possible risk factor for developing colorectal cancer. Recommendations for further studies include pooling of individual data to verify results from the study and to facilitate evaluation of multigenic effects and detailed analysis of effect modification by environmental and lifestyle factors.     

Genetic variation in a miR-335 binding site in BIRC5 alters susceptibility to lung cancer in Chinese Han populations

Polymorphisms in 3′ untranslated region (UTR) of cancer-related genes might affect their regulation by microRNAs (miRNAs) and thereby contribute to carcinogenesis. In this study, we screened single nucleotide polymorphisms (SNPs) in 3′ UTR of cancer-related genes and investigated their effects on risk of lung cancer. First, we genotyped seven SNPs in a Chinese Han population with 600 lung cancer patients and 600 matched healthy controls and found that compared with the TT genotype of rs2239680 in 3′ UTR of baculoviral IAP repeat containing 5 (BIRC5), C allele was associated with a significantly increased risk of lung cancer and advanced pathologic stage, with the odds ratio for participants carrying the CT or CC genotype being 1.50 [95% confidence interval (CI) 1.20–1.89, P < 0.01] and 2.29 (95% CI 1.64–3.18, P < 0.01), respectively. These results were further replicated and confirmed in another independent population with 1000 lung cancer cases and 1000 matched healthy controls. In support of the postulation that the 3′ UTR SNP may directly affect miRNA-binding site, reporter gene assays indicated BIRC5 was a direct target of miR-335, and the rs2239680 T > C change resulted in altered regulation of BIRC5 expression. Moreover, BIRC5 was over expressed in lung cancer tissues compared with the normal lung tissues, and the protein levels of BIRC5 correlated with SNP genotypes in normal lung tissues. Our findings defined a 3′ UTR SNP in human BIRC5 oncogene that may increase individual susceptibility to lung cancer probably by attenuating the interaction between miR-335 and BIRC5.     

Significant association between GSTT1 null genotype and susceptibility to pancreatic cancer

Many studies have investigated the association between glutathione S-transferase T1 (GSTT1) polymorphism and risk for pancreatic cancer, but those studies have yielded contradictory findings on the association. We performed a comprehensive search in the PubMed, EMBASE, and the Chinese National Knowledge Infrastructure databases to identify relevant studies. A meta-analysis was performed to examine the association between GSTT1 polymorphism and susceptibility to pancreatic cancer by calculating the pooled odds ratios (ORs) and corresponding 95 % confidence intervals (95 % CIs). Eight studies involving a total of 4,437 individuals were included. Overall, significantly increased pancreatic cancer risk was associated with GSTT1 null genotype when all studies were pooled into the meta-analysis (random effects OR = 1.61, 95 % CI 1.06–2.44; P = 0.025). Significantly increased risk of pancreatic cancer was also found for GSTT1 null genotype in Asians when stratified by ethnicity (fixed effects OR = 2.67, 95 % CI 1.74–4.09; P < 0.001). The findings demonstrate that GSTT1 null genotype have a modest effect on the genetic susceptibility to pancreatic cancer, and GSTT1 null genotype is associated with increased risk of pancreatic cancer.     

Significant association of glutathione S-transferase T1 null genotype with esophageal cancer risk: a meta-analysis

Recent studies on the association between glutathione S-transferase T1 (GSTT1) polymorphism and risk of esophageal cancer showed inconclusive results. To clarify this possible association, we conducted a meta-analysis of published studies. 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 this association. We summarized the data on the association between GSTT1 null genotype and risk of esophageal cancer in the overall population, and performed subgroup analyses by ethnicity. Finally, a total of 24 independent studies including a total of 7,801 subjects (2,965 cases and 4,836 controls) were eligible for meta-analysis. In the overall analysis, there was no significant association between GSTT1 null genotype and esophageal cancer risk (OR = 1.15, 95 % CI 0.99–1.33, P = 0.067). However, meta-analysis of adjusted ORs showed a significant association between GSTT1 null genotype and increased risk of esophageal cancer (OR = 1.30, 95 % CI 1.08–1.56, P = 0.005). Subgroup analyses by ethnicity showed there was an obvious association between GSTT1 null genotype and increased risk of esophageal cancer in East Asians (OR = 1.24, 95 % CI 1.10–1.39, P < 0.001), but not in Caucasians (OR = 0.89, 95 % CI 0.71–1.11, P = 0.300). There was no obvious risk of publication bias in this meta-analysis (Egger’s test, P = 0.784). This meta-analysis demonstrates that GSTT1 null genotype is independently associated with increased risk of esophageal cancer, and a race-specific effect may exist in this association.     

Effects of polymorphisms in translesion DNA synthesis genes on lung cancer risk and prognosis in Chinese men

PurposeTranslesion DNA synthesis (TLS) plays an important role in promoting replication through DNA lesions. Genetic polymorphisms in TLS genes may have potential roles in lung cancer development in humans.MethodsWe evaluated the association between genetic variants in six TLS genes and the risk and survival of lung cancer in a case–control study in China. Included in the study are 224 lung cancer patients and 448 healthy controls.ResultsCarriers of the G allele of POLκ rs5744724 had significantly reduced risk of lung cancer (odds ratio (OR) = 0.62, 95% confidence interval (CI): 0.44–0.89), comparing with those carrying the C allele, and the AA genotype of PCNA rs25406 was also associated with significantly decreased cancer risk compared with the major homozygote alleles (OR = 0.47, 95% CI: 0.25–0.86). Haplotype analysis showed that subjects with the POLκ C-G (rs5744533–rs5744724) haplotype had decreased risk of lung cancer (OR = 0.69, 95% CI: 0.49–0.98), comparing with those carrying the C-C haplotype. Besides, the heterozygote of REV1 rs3087386 and rs3792136 were independent prognostic factors for lung cancer survival with hazard radio (HR) 1.54 (95% CI: 1.12–2.12) and 1.44 (95% CI: 1.06–1.97) respectively.ConclusionsOur findings suggested that genetic variants in POLκ and PCNA genes may play roles in the susceptibility of lung cancer, and REV1 gene may have roles in lung cancer survival in Chinese men.     

Meta-analysis of the association of glutathione S-transferase T1 null/presence gene polymorphism with the risk of gastric carcinoma

A possible association of glutathione S-transferase T1 (GSTT1) null/presence gene polymorphism and an increased risk of developing gastric carcinoma is still unclear and hotly debated. This investigation was performed to assess the association of the GSTT1 null/presence gene polymorphism with the risk of gastric carcinoma via a meta-analysis to increase sample size and statistical significance. PubMed, Cochrane Library and CBM-disc (China Biological Medicine Database) were searched on March 1, 2013, association reports were identified, and eligible studies were recruited and synthesized. Fifty-two reports were found to be suitable for this meta-analysis for the association of the GSTT1 null genotype with gastric carcinoma risk. The results showed that there was a significantly increased gastric carcinoma risk when the GSTT1 null genotype was present in the overall population (OR 1.21, 95 % CI 1.11–1.32, P < 0.0001), Caucasians (OR 1.25, 95 % CI 1.05–1.48, P = 0.01), East-Asians (OR 1.18, 95 % CI 1.06–1.31, P = 0.003), and Chinese (OR 1.24, 95 % CI 1.07–1.44, P = 0.005). However, no statistically relevant association could be established for the Indian ethnic group (OR 1.33, 95 % CI 0.94–1.90, P = 0.11). In conclusion, the GSTT1 null genotype is associated with an increased gastric carcinoma risk in the overall population, Caucasians, East-Asians, and Chinese.     

Lack of association between glutathione S-transferase T1 gene polymorphism and laryngeal cancer susceptibility: a meta-analysis based on 2,124 cases and 2,059 controls

Studies investigating the association between glutathione S-transferase T1 (GSTT1) gene polymorphism and laryngeal cancer susceptibility have reported conflicting results. The aim of the present study was to conduct a meta-analysis assessing the possible association of GSTT1 gene polymorphism with laryngeal cancer risk. The relevant studies were identified through a search of PubMed, Embase, ISI Web of Knowledge and Chinese National Knowledge Infrastructure until May 2011. Twelve studies were included in the present meta-analysis, which described a total of 2124 laryngeal cancer cases and 2059 controls. The overall odds ratio (OR) for GSTT1 null genotype was 1.40 (95% CI = 0.90-2.16). When stratifying for race, the pooled ORs for GSTT1 null genotype were 1.07 (95% CI = 0.81-1.41) in Caucasians and 5.63 (95% CI = 1.00-31.83) in Asians. The pooled ORs for GSTT1 null genotype were 1.03 (95% CI = 0.71-1.49) in population-based studies and 2.39 (95% CI = 0.73-7.86) in hospital-based studies, stratifying for study design. This meta-analysis suggested that there was lack of association between GSTT1 gene polymorphism and laryngeal cancer risk. However, larger scale primary studies are still required to further evaluate the interaction of GSTT1 gene polymorphism with laryngeal cancer risk.     

A functional polymorphism of lymphotoxin-alpha (LTA) gene rs909253 is associated with gastric cancer risk in an Asian population

BackgroundThe potentially functional polymorphism, rs909253 (+252 G>A), in the intron region of the LT-α (TNF-β) gene has been implicated in the risk of gastric cancer (GC) in some individually published studies, but others have shown inconsistent and inconclusive results.MethodsWe conducted a meta-analysis to assess the association between the lymphotoxin-α gene (LTA) + 252 (G>A) polymorphism and gastric cancer susceptibility.ResultsWe demonstrate that there were no significant associations in single-locus analysis between the polymorphism of LTA and gastric cancer risk in all subjects; however, when studies were stratified by ethnicity, these polymorphisms of LTA were found to be associated with a significant cancer risk in different genetic models in an Asian population (heterozygote [GA genotype] comparison: odds ratio [OR] = 1.29, 95% confidence interval [CI]: 1.01–1.65, P = 0.038) in which the risk in the subjects was more than 70% (12 studies with 2074 cases and 3690 controls). Moreover, the susceptibility to gastric carcinogenesis has a substantial influence on the population-attributable risk by modulating the effects of environmental risk factors such as Helicobacter pylori infection (OR = 1.77, 95%CI: 1.05–2.99, P = 0.032).ConclusionsThe present meta-analysis results suggest that the LTA rs909253 GA genotype is a possible risk factor for developing gastric cancer in the Asian population, especially those with H. pylori infection.     

Interactions between Glutathione-S-Transferase M1, T1 and P1 polymorphisms and smoking,and increased susceptibility to esophageal squamous cell carcinoma

Background: A complex of genetic and environmental factors is involved in carcinogenesis of the esophageal squamous cell carcinoma (ESCC). Glutathione-S-Transferases (GSTs) are phase-II enzymes playing role in detoxification of carcinogen electrophiles. Genetic polymorphisms of GSTM1, GSTT1 and GSTP1 in association with some environmental factors and their impact on esophageal cancer susceptibility were assessed in the Iranian population. Methods: Genomic DNA of peripheral blood leukocytes from 148 confirmed esophageal cancer cases and 137 healthy individuals as control group was assayed for restriction fragment length polymorphisms in the GSTP1 loci by PCR amplification followed by digestion with Alw26I. Deletion of the GSTM1 and GSTT1 genes was detected by multiplex PCR. A data-mining method based on decision trees was applied to produce a predictive model of interactions between genotypes. Results: Smoking was independently associated with ESCC (p < 0.05, OR: 2.286, 95% CI = 1.311–3.983). Smoking along with GSTP1 Val/Val genotype was associated to ESCC (p < 0.001, OR: 3.886, 95% CI = 1.830–8.251), while non-smokers with GSTP1 Val/Val were significantly more frequent in non-cancerous group. (p = 0.007, OR: 0.507, 95% CI = 0.309–0.830). Conclusions: Data-mining methods are useful tools to map out a scheme for predicting complex relations and combinations of different genotypes. Genotyping analysis of GSTP1 together with assessment of smoking seems to be important in determining the risk of ESCC in the Iranian population.     

The association between UGT1A7 polymorphism and cancer risk: a meta-analysis

Background: studies investigating the associations between UDP-glucuronosyltransferase 1A7 (UGT1A7) gene polymorphisms and various carcinomas risk reported conflicting results. To derive a more precise estimation of the association, we have conducted a meta-analysis. Methods: data were collected from the following electronic databases: PubMed, Medline and Chinese Biomedical Literature Database, with the last report up to September 2011. Case–control studies containing available genotype frequencies of UGT1A7 were chose. The odds ratio (OR) and its 95% confidence interval (95%CI) were used to assess the strength of association. Results: a total of 22 separate case–control studies including 3852 cases and 5604 controls based on the search criteria were involved in this meta-analysis. The combined results based on all studies showed that there was a statistically significant link between UGT1A7*3 allele and cancer risk (OR = 1.31, 95%CI = 1.14–1.50, P = 0.0001). In the stratified analysis by racial descent, significant increased risk was found in Asian population for UGT1A7*3 allele (OR = 1.41, 95%CI = 1.22–1.63, P < 0.00001). No significant associations were found between the UGT1A7 polymorphism and cancer susceptibility among Caucasians and African-Americans. In the subgroup analysis by cancer types, significant associations were found in UGT1A7*2 allele (OR = 1.23, 95%CI = 1.06–1.43, P = 0.006) and *3 allele (OR = 1.51, 95%CI = 1.11–2.06, P = 0.009) for hepatocellular carcinoma, *3 allele for lung cancer (OR = 1.36, 95%CI = 1.11–1.68, P = 0.004) and for bladder cancer (OR = 1.50, 95%CI = 1.09–2.07, P = 0.01). Conclusions: This meta-analysis suggests that the UGT1A7*3 allele is a risk factor for cancer among Asians, especially for hepatocellular carcinoma.