Individual and combined effects of the GSTM1, GSTT1, and GSTP1 polymorphisms on type 2 diabetes mellitus risk: A systematic review and meta-analysis

Risk of Cardiovascular Complications Among Type 2 Diabetes Mellitus Patients with GSTP1 Genetic Polymorphism: A Nested Case-Control Study and Docking Studies

The genetic alteration in the antioxidant gene Glutathione-S-Transferases Pi 1 (GSTP1) namely GSTP1*IIe105Val (rs1695) and GSTP1*Ala114Val (rs1138272) changes the individual susceptibility to cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM) by altering the substrate binding and catalytic activity. This study aims to investigate the association of GSTP1 rs1695 and rs1138272 polymorphism with CVD development in T2DM patients. Genotyping was performed with 400 study participants-group I: control; group II: T2DM; group III: CVD; and group IV: T2DM/CVD [n = 100 each] by PCR-RFLP. The rs1695 and rs1138272 polymorphism were docked against NPACT and NUBBE database and virtually screened using glide. The study reported that rs1695 polymorphism was associated with T2DM risk under dominant and allelic genetic models [OR = 1.97(1.08-3.59) p = 0.02 and OR = 1.79(1.20-2.66) p = 0.003, respectively]. The val/val genotype, dominant, recessive model, and T allelic genetic model were associated with increased CVD risk [OR = 4.15(1.97-8.73) p =  < 0.01; OR = 3.16(1.65-6.04) p =  < 0.01; OR = 3.47(1.91-6.31) p =  < 0.01; and OR = 2.94(1.95-4.43) p =  < 0.01, respectively]. In contrast, rs1695 polymorphism was not associated with CVD development among patients with T2DM. In rs1138272, the wild genotype was only detected and neither heterozygous nor val/val genotype was observed. The docking analysis revealed that the Ile105Val mutation plays a significant role in altering the GSTP1 capacity compared to the Ala115Val mutation. This suggests that the Ile105Val mutation has a greater impact on the protein's structure, function, or susceptibility to diseases compared to the Ala115Val mutation. In summary, genetic alteration in GSTP1 rs1695 potentially contributes to an increased risk of T2DM and CVD.

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.

Polygenic Variants Linked to Oxidative Stress and the Antioxidant System Are Associated with Type 2 Diabetes Risk and Interact with Lifestyle Factors

Oxidative stress is associated with insulin resistance and secretion, and antioxidant systems are essential for preventing and managing type 2 diabetes (T2DM). This study aimed to explore the polygenic variants linked to oxidative stress and the antioxidant system among those associated with T2DM and the interaction of their polygenic risk scores (PRSs) with lifestyle factors in a large hospital-based cohort (n = 58,701). Genotyping, anthropometric, biochemical, and dietary assessments were conducted for all participants with an average body mass index of 23.9 kg/m². Genetic variants associated with T2DM were searched through genome-wide association studies in participants with T2DM (n = 5383) and without T2DM (n = 53,318). The Gene Ontology database was searched for the antioxidant systems and oxidative stress-related genes among the genetic variants associated with T2DM risk, and the PRS was generated by summing the risk alleles of selected ones. Gene expression according to the genetic variant alleles was determined on the FUMA website. Food components with low binding energy to the GSTA5 protein generated from the wildtype and mutated GSTA5_rs7739421 (missense mutation) genes were selected using in silico analysis. Glutathione metabolism-related genes, including glutathione peroxidase (GPX)1 and GPX3, glutathione disulfide reductase (GSR), peroxiredoxin-6 (PRDX6), glutamate-cysteine ligase catalytic subunit (GCLC), glutathione S-transferase alpha-5 (GSTA5), and gamma-glutamyltransferase-1 (GGT1), were predominantly selected with a relevance score of >7. The PRS related to the antioxidant system was positively associated with T2DM (ORs = 1.423, 95% CI = 1.22-1.66). The active site of the GASTA proteins having valine or leucine at 55 due to the missense mutation (rs7739421) had a low binding energy (<-10 kcal/mol) similarly or differently to some flavonoids and anthocyanins. The PRS interacted with the intake of bioactive components (specifically dietary antioxidants, vitamin C, vitamin D, and coffee) and smoking status (p < 0.05). In conclusion, individuals with a higher PRS related to the antioxidant system may have an increased risk of T2DM, and there is a potential indication that exogenous antioxidant intake may alleviate this risk, providing insights for personalized strategies in T2DM prevention.

Glutathione S-Transferase P1 Genetic Variant's Influence on the HbA1c Level in Type Two Diabetic Patients

GST (glutathione S-transferases) are capable of influencing glucose homeostasis, probably through regulation of the response to oxidant stress. The aim of our study was to investigate the relationship between GSTP1 gene polymorphism and glycated hemoglobin (HbA1c) levels in type two diabetic (T2D) patients. A total of 307 T2D patients were included. Analysis of the GSTP1 gene polymorphism (rs1695) was conducted using the TaqMan qPCR method endpoint genotyping. HbA1c was determined using a COBAS 6000 autoanalyzer. A univariable linear regression and multivariable linear regression model were used to investigate the association between mean HbA1c level and GSTP1 gene polymorphism, age at T2D diagnosis, T2D duration, therapy with insulin, gender, BMI, smoking status. GSTP1 Val/Val genotype, age at T2D diagnosis, T2D duration and therapy with insulin were statistically significant contributors to HbA1c levels (p < 0.05). Multivariable regression analysis revealed that GSTP1 (Val/Val vs. Ile/Ile) was associated with higher HbA1c even after adjustment for variables that showed a statistically significant relationship with HbA1c in univariable analyses (p = 0.024). The results suggest that GSTP polymorphism may be one of the risk factors for higher HbA1c in T2D patients. Our study is limited by the relatively small sample size, cross-sectional design, and lack of inclusion of other oxidative stress-related genetic variants.