A meta-analysis of the association of glutathione S-transferase P1 gene polymorphism with the susceptibility of breast cancer

The importance of polymorphisms in the genes encoding glutathione S-transferase isoenzymes in development of selected cancers and cardiovascular diseases

Glutathione S-transferases are a family of enzymes, whose main role is to detoxify cells from many exogenous factors, such as xenobiotics or carcinogens. It has also been proven that changes in the genes encoding these enzymes may affect the incidence of selected cancers and cardiovascular diseases. The aim of this study was to review the most important reports related to the role of glutathione S-transferases in the pathophysiology of two of the most common diseases in modern society - cancers and cardiovascular diseases. It was shown that polymorphisms in the genes encoding glutathione S-transferases are associated with the development of these diseases. However, depending on the ethnic group, the researchers obtained divergent results related to this field. In the case of the GSTP1 A/G gene polymorphism was shown an increased incidence of breast cancer in Asian women, while this relationship in European and African women was not found. Similarly. In the case of cardiovascular diseases, the differences in the influence of GSTM1, GSTT1, GSTP1 and GSTA1 polymorphisms on their development or lack of it depending on the continent were shown. These examples show that the development of the above-mentioned diseases is not only influenced by genetic changes, but their pathophysiology is more complex. The mere presence of a specific genotype within a studied polymorphism may not predispose to cancer, but in combination with environmental factors, which often depend on the place of residence, it may elevate the chance of developing the selected disease.

Association of GSTP1 p.Ile105Val (rs1695, c.313A > G) Variant with the Risk of Breast Carcinoma among Egyptian Women

Several reports examined the association of the GSTP1 p.Ile105Val (rs1695, c.313A > G) variant with the elevated risk of multiple cancerous diseases involving breast carcinoma, but with inconclusive findings. The primary purpose of this study is to test the association of this essential variant with the risk of breast carcinoma among Egyptian females. This case-control study was conducted based on 200 participants involving 100 women diagnosed with breast carcinoma and 100 unrelated cancer-free controls from the same district. The genomic DNA for all participants was genotyped utilizing T-ARMS-PCR procedure. The frequencies of the GSTP1 p.Ile105Val (rs1695, c.313A > G) variant indicated a statistically significant with the elevated risk of breast carcinoma under various genetic models, including allelic (OR = 2.48, P-value < 0.001) and dominant (OR = 2.36, P-value = 0.003) models. In conclusion, the GSTP1 p.Ile105Val (rs1695, c.313A > G) variant was considered as an independent risk factor for breast carcinoma among Egyptian women.

Association analysis of rs1695 and rs1138272 variations in GSTP1 gene and breast cancer susceptibility

Background:

The glutathione S transferases P1 (GSTP1) is one of the common type of the GSTs family. This gene has several genetic polymorphisms that the rs1695 and rs1138272 are the most common variations in this gene. This study aimed to examine the association of these genetic variations with breast cancer risk which was followed by bioinformatics analysis.

Materials and Methods:

In a case-control study, 200 participants including 100 women with breast cancer and 100 healthy women were enrolled. After blood sample collection and DNA extraction, the total genomic DNA was extracted from this sample. The SNPeffects online software was employed to evaluate the effects of rs1695 genetic variation on the GSTP1 protein structure.

Results:

Our data revealed that there is a significant association between rs1695 genetic variation and the risk of breast cancer in homozygote (OR= 3.1532, 95%CI= 1.1072 to 8.9798, p= 0.0315) and allelic (OR= 1.6098, 95%CI= 1.0577 to 2.4500, p= 0.0263) genetic comparisons. This despite the fact that the rs1138272 polymorphism was not associated with breast cancer risk. Our bioinformatics analysis based on WALTZ output showed that the rs1695 polymorphism reduces the amyloid propensity of the GSTP1 enzyme (dWALTZ= -228.00).

Conclusions:

Based on our findings, the rs1695 genetic variation is a genetic risk factor for breast cancer and it could be considered as a biomarker for screening of susceptible women.

Individual and combined effects of GSTM1, GSTT1, and GSTP1 polymorphisms on breast cancer risk: A meta-analysis and re-analysis of systematic meta-analyses

Background

Fourteen previous meta-analyses have been published to analyze the polymorphisms of individual GSTM1 present/null, GSTT1 present/null, and GSTP1 IIe105Val on breast cancer (BC) risk. However, their meta-analyses did not explore the combined effects of the three genetic polymorphisms on BC risk. In addition, they did not evaluate the credibility of statistically significant associations. Furthermore, a multitude of new articles have been published on these themes, and therefore a meta-analysis and re-analysis of systematic previous meta-analyses were performed to further explore these issues.

Objectives

To determine the association between the individual and combined effects of GSTM1, GSTT1, and GSTP1 polymorphisms on breast cancer risk.

Methods

Crude odds ratios (ORs) and their 95% confidence intervals (CIs) were applied to estimate the association between individual and combined effects of GSTM1, GSTT1, and GSTP1 polymorphisms on BC risk. To evaluate the credibility of statistically significant associations in the current and previous meta-analyses, we applied the the false-positive report probabilities (FPRP) test and the Venice criteria.

Results

101 publications were selected to evaluate the individual and combined effects of GSTM1, GSTT1 and GSTP1 polymorphisms on BC risk. Overall, statistically significant elevated BC risk was found in any individual and combined effects of GSTM1 present/null, GSTT1 present/null, and GSTP1 IIe105Val polymorphisms. However, when we restricted studies only involving with high-quality, matching, HWE, and genotyping examination performed blindly or with quality control, significantly increased BC risk was only found in overall population for GSTM1 null genotype, among all populations, Caucasians, and postmenopausal women for the combined effects of GSTM1 and GSTT1 polymorphisms, and in overall analysis for the combined effects of GSTM1, GSTT1, and GSTP1 IIe105Val polymorphisms. Further, less-credible positive results were identified when we evaluated the credibility of positive results of the current and previous meta-analyses.

Conclusions

This meta-analysis indicates that the individual and combined effects of GSTM1, GSTT1 and GSTP1 polymorphisms may be not associated with increased BC risk.

Association of glutathione S-transferase T1, M1, and P1 polymorphisms in the breast cancer risk: a meta-analysis

BACKGROUND

Several case-control studies investigating the relationship between genetic polymorphisms of glutathione S-transferase (GST) M1, GSTT1, and GSTP1 (rs1695) and the risk of breast cancer have reported contradictory results. We therefore performed a meta-analysis to clarify this issue.

MATERIALS AND METHODS

An updated meta-analysis using PubMed and Web of Knowledge databases for the eligible case-control studies was performed. Random- or fixed-effects model was used.

RESULTS

A total of 10,067 cancer cases and 12,276 controls in 41 independent case-control studies from 19 articles were included in this meta-analysis. Significant increase in risk of breast cancer for Asians was found in GSTM1-null genotype (P=0.012, odds ratio [OR] =1.17, 95% confidence interval [CI] =1.04-1.32) and GSTT1-null genotype (P=0.039, OR =1.19, 95% CI =1.01-1.41). In addition, our results showed that the GSTP1 (rs1695) polymorphisms can significantly increase the risk among Caucasians (P=0.042, OR =1.16, 95% CI =1.01-1.34). Sensitivity analysis and publication bias further confirmed the dependability of the results in this meta-analysis.

CONCLUSION

Our results demonstrate that both GSTM1- and GSTT1-null polymorphisms are associated with an increased risk of breast cancer in Asians and that GSTP1 Val105Ile (rs1695) polymorphism is associated with an increased breast cancer risk in Caucasians.

The synergistic effect between the Mediterranean diet and GSTP1 or NAT2 SNPs decreases breast cancer risk in Greek-Cypriot women

PURPOSE

Xenobiotic metabolism is related to the interplay between diet and breast cancer (BC) risk. This involves detoxification enzymes, which are polymorphic and metabolise various dietary metabolites. An important characteristic of this pathway is that chemoprotective micronutrients can act not only as substrates but also as inducers for these enzymes. We investigated whether functional GSTP1 (p.Ile105Val-rs1695), NAT2 (590G>A-rs1799930) SNPs and GSTM1 and GSTT1 deletion polymorphisms could modulate the effect of the Mediterranean diet (MD) on BC risk, in Greek-Cypriot women.

METHODS

Genotyping was performed on women from the MASTOS case-control study of BC in Cyprus. A 32-item food-frequency questionnaire was used to obtain dietary intake information. A dietary pattern, which closely resembles the MD (high loadings of vegetables, fruit, legumes and fish), was previously derived with principal component analysis and was used as our dietary variable.

RESULTS

GSTT1 null genotype increased BC risk compared with the homozygous non-null GSTT1 genotype (OR 1.21, 95 % CI 1.01-1.45). Increasing adherence to the MD reduced BC risk in women with at least one GSTP1 Ile allele (OR for Ile/Ile = 0.84, 95 % CI 0.74-0.95, for Ile/Val = 0.73, 95 % CI 0.62-0.85) or one NAT2 590G allele (OR for 590 GG = 0.73, 95 % CI 0.63-0.83, for 590 GA = 0.81, 95 % CI 0.70-0.94). p interaction values were not, however, statistically significant.

CONCLUSION

The homozygous null GSTT1 genotype could be a risk allele for BC among Greek-Cypriot women. The anticarcinogenic effects of the high adherence to MD against BC risk could also be further enhanced when combined with the wild-type alleles of the detoxification GSTP1 or NAT2 SNPs.

Association between glutathione S-transferases P1 Ile105Val polymorphism and susceptibility to esophageal cancer: evidence from 20 case-control studies

Available epidemiological studies had estimated the correlation between glutathione S-transferases P1 (GSTP1) Ile105Val polymorphism and esophageal cancer (EC) risk. However, the conclusions were controversial and inconclusive. An updated meta-analysis was conducted to explore whether GSTP1 polymorphism could be contributed to the EC risk. Ultimately, a total of 2,992 cases and 4,758 controls from 20 previous studies were included. Crude odds ratios (ORs) with 95 % confidence intervals (95 % CIs) were used to assess the strength of the associations. Pooled results suggested that GSTP1 Ile105Val polymorphism significantly increased the risk of developing EC in Caucasians under three genetic models (G vs. A, OR 1.146, 95 % CI 1.031-1.275, P = 0.012, I(2) = 30.40 %; GA vs. AA, OR 1.208, 95 % CI 1.036-1.408, P = 0.016, I(2) = 50.30 %; GG+GA vs. AA, OR 1.219, 95 % CI 1.053-1.410, P = 0.008, I(2) = 44.50 %). However, no significant correlation was found in Asians, African and mixed ethnicities analyses. Moreover, similar results were detected for any genetic model in esophageal squamous cell carcinoma and esophageal adenocarcinoma when stratifying for pathologic types. This meta-analysis provides new evidences that GSTP1 Ile105Val gene polymorphism contributes to EC susceptibility in Caucasians.

Association between vitamin D receptor gene Cdx2 polymorphism and breast cancer susceptibility

Vitamin D receptor (VDR) gene polymorphisms have been reported to influence susceptibility to breast cancer. However, published findings on the association between VDR Cdx2 polymorphism and breast cancer susceptibility are conflicting. To get a precise estimation of the association between VDR Cdx2 polymorphism and breast cancer susceptibility, we conducted a meta-analysis of four case-control studies with a total of 8,880 subjects (3,841 cases and 5,039 controls). The results showed that VDR Cdx2 polymorphism was not associated with risk of breast cancer (A versus G: OR = 0.96, 95% CI 0.84-1.09; AA versus GG: OR = 0.97, 95% CI 0.64-1.45; AA/GA versus GG: OR = 0.94, 95% CI 0.80-1.10; AA versus GG/GA: OR = 0.99, 95% CI 0.65-1.51). Subgroup analysis in Caucasians also showed that VDR Cdx2 polymorphism was not associated with risk of breast cancer in Caucasians. However, there was a significant association in Africans (A versus G: OR = 0.75, 95% CI 0.60-0.94; AA versus GG: OR = 0.53, 95% CI 0.29-0.99; AA/GA versus GG: OR = 0.75, 95% CI 0.57-0.97). Therefore, the association between VDR Cdx2 polymorphism and breast cancer susceptibility is only found in Africans. More studies are needed to further assess the association in Asians or Africans.