Protein carbonyl levels, glutathione S-transferase polymorphisms and risk of colorectal cancer

Association of glutathione S-transferase 1 (GSTP1) polymorphisms with Breast Cancer susceptibility

Hereditary and environmental variables have a role in the development of breast cancer. This study aimed to examine the links between genetic Variations in the GSTP1 gene and Predisposition to breast cancer in an Iraqi population. The research included 40 Iraqi female breast cancer patients and 20 healthy volunteers. GSTP1-1695 A/G gene polymorphisms were investigated using polymerase chain reaction in Real-time (RT-PCR). The results showed the GSTP1 frequency of the wild GG genotypes was showed significantly (P<0.01) higher in healthy women in comparison with Breast cancer women (GG, 80% vs. 32.5%, respectively; furthermore, heterozygous AG genotypes were significantly higher in Breast cancer women in comparison with healthy women 42.5% vs. 20%, respectively at (P<0.01). While the mutant AA genotype (25%) in patient women appeared significantly (P<0.01) higher compared to healthy women (0.0%). Finally, we discovered a connection between GSTP1 polymorphisms and a higher chance of developing breast cancer in an Iraqi female population sample. Keywords: glutathione S-transferase1, breast cancer, polymorphism.

Individual and combined effects of GSTM1 and GSTT1 polymorphisms on colorectal cancer risk: an updated meta-analysis

BACKGROUND

The presence or absence of glutathione S-transferase M1 gene (GSTM1) and glutathione S-transferase T1 gene (GSTT1) polymorphisms, and their combined effects have been suggested as a risk factor for colorectal cancer (CRC). However, the results are inconsistent.

OBJECTIVES

An updated meta-analysis was performed to solve the controversy.

METHODS

Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines were used.

RESULTS

Overall, the GSTM1 null genotype was associated with an increased CRC risk in Caucasians (odds ratio (OR) = 1.14, 95% confidence interval (CI): 1.05-1.23), Asians (OR = 1.19, 95% CI: 1.08-1.32), high-quality studies (OR = 1.12, 95% CI: 1.06-1.18). Moreover, the GSTM1 null genotype was also associated with an increased colon cancer risk (OR = 1.32, 95% CI: 1.16-1.51). The GSTT1 null genotype was also associated with an increased CRC risk in Asians (OR = 1.08, 95% CI: 1.02-1.15) and Caucasians (OR = 1.24, 95% CI: 1.09-1.41). Moreover, The GSTT1 null genotype was associated with an increased rectal cancer risk (OR = 1.13, 95% CI: 1.01-1.27, I2 = 8.3%) in subgroup analysis by tumor location. Last, the GSTM1 null/GSTT1 null genotype was associated with an increased CRC risk in Asians.

CONCLUSION

This meta-analysis indicates that the GSTM1 and GSTT1 null genotypes are associated with increased CRC risk in Asians and Caucasians, and the GSTM1 null/GSTT1 null genotype was associated with increased CRC risk in Asians.

Approaches and Methods to Measure Oxidative Stress in Clinical Samples: Research Applications in the Cancer Field

Reactive oxygen species (ROS) are common by-products of normal aerobic cellular metabolism and play important physiological roles in intracellular cell signaling and homeostasis. The human body is equipped with antioxidant systems to regulate the levels of these free radicals and maintain proper physiological function. However, a condition known as oxidative stress (OS) occurs, when ROS overwhelm the body's ability to readily detoxify them. Excessive amounts of free radicals generated under OS conditions cause oxidative damage to proteins, lipids, and nucleic acids, severely compromising cell health and contributing to disease development, including cancer. Biomarkers of OS can therefore be exploited as important tools in the assessment of disease status in humans. In the present review, we discuss different approaches used for the evaluation of OS in clinical samples. The described methods are limited in their ability to reflect on OS only partially, revealing the need of more integrative approaches examining both pro- and antioxidant reactions with higher sensitivity to physiological/pathological alternations. We also provide an overview of recent findings of OS in patients with different types of cancer. Identification of OS biomarkers in clinical samples of cancer patients and defining their roles in carcinogenesis hold great promise in promoting the development of targeted therapeutic approaches and diagnostic strategies assessing disease status. However, considerable data variability across laboratories makes it difficult to draw general conclusions on the significance of these OS biomarkers. To our knowledge, no adequate comparison has yet been performed between different biomarkers and the methodologies used to measure them, making it difficult to conduct a meta-analysis of findings from different groups. A critical evaluation and adaptation of proposed methodologies available in the literature should therefore be undertaken, to enable the investigators to choose the most suitable procedure for each chosen biomarker.

Gene Expression, Oxidative Stress, and Senescence of Primary Coronary Endothelial Cells Exposed to Postprandial Serum of Healthy Adult and Elderly Volunteers after Oven-Cooked Meat Meals

Epidemiological studies have linked high consumption of meat with major age-related diseases including cardiovascular diseases. Abnormal postprandial increases in plasma lipids after a meat meal have been hypothesized among the pathogenetic mechanisms. However, it is still unknown if the postprandial serum derived after a normal meat meal is able to affect endothelial function, and if the type of meat and the age of the donors are critical factors. Here, we show the effects of postprandial sera derived from healthy adults and elderly volunteers who consumed meat meals on human coronary artery endothelial cell (HCAEC) oxidative stress, gene expression, DNA damage, and cellular senescence. We observed that a single exposure to postprandial serum induces a slight increase in ROS that is associated with modulation of gene expression pathways related to oxidative stress response and metabolism. The postprandial-induced increase in ROS is not associated with a measurable DNA oxidative damage. However, repeated exposure to postprandial serum induces an acceleration of cellular senescence. Taking into account the deleterious role of cellular senescence in age-related vascular diseases, the results suggest a new mechanism by which excessive meat consumption and time spent in postprandial state may affect health status during aging.

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.

Proteomic indicators of oxidation and hydration state in colorectal cancer

New integrative approaches are needed to harness the potential of rapidly growing datasets of protein expression and microbial community composition in colorectal cancer. Chemical and thermodynamic models offer theoretical tools to describe populations of biomacromolecules and their relative potential for formation in different microenvironmental conditions. The average oxidation state of carbon (Z_C) can be calculated as an elemental ratio from the chemical formulas of proteins, and water demand per residue (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}${\overline{n}}_{{\mathrm{H}}_{2}\mathrm{O}}$\end{document}n¯H2O) is computed by writing the overall formation reactions of proteins from basis species. Using results reported in proteomic studies of clinical samples, many datasets exhibit higher mean Z_C or \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}${\overline{n}}_{{\mathrm{H}}_{2}\mathrm{O}}$\end{document}n¯H2O of proteins in carcinoma or adenoma compared to normal tissue. In contrast, average protein compositions in bacterial genomes often have lower Z_C for bacteria enriched in fecal samples from cancer patients compared to healthy donors. In thermodynamic calculations, the potential for formation of the cancer-related proteins is energetically favored by changes in the chemical activity of H₂O and fugacity of O₂ that reflect the compositional differences. The compositional analysis suggests that a systematic change in chemical composition is an essential feature of cancer proteomes, and the thermodynamic descriptions show that the observed proteomic transformations in host tissue could be promoted by relatively high microenvironmental oxidation and hydration states.

Oxidative Stress and Carbonyl Lesions in Ulcerative Colitis and Associated Colorectal Cancer

Oxidative stress has long been known as a pathogenic factor of ulcerative colitis (UC) and colitis-associated colorectal cancer (CAC), but the effects of secondary carbonyl lesions receive less emphasis. In inflammatory conditions, reactive oxygen species (ROS), such as superoxide anion free radical (O2 (∙-)), hydrogen peroxide (H2O2), and hydroxyl radical (HO(∙)), are produced at high levels and accumulated to cause oxidative stress (OS). In oxidative status, accumulated ROS can cause protein dysfunction and DNA damage, leading to gene mutations and cell death. Accumulated ROS could also act as chemical messengers to activate signaling pathways, such as NF-κB and p38 MAPK, to affect cell proliferation, differentiation, and apoptosis. More importantly, electrophilic carbonyl compounds produced by lipid peroxidation may function as secondary pathogenic factors, causing further protein and membrane lesions. This may in turn exaggerate oxidative stress, forming a vicious cycle. Electrophilic carbonyls could also cause DNA mutations and breaks, driving malignant progression of UC. The secondary lesions caused by carbonyl compounds may be exceptionally important in the case of host carbonyl defensive system deficit, such as aldo-keto reductase 1B10 deficiency. This review article updates the current understanding of oxidative stress and carbonyl lesions in the development and progression of UC and CAC.

GSTM1 polymorphism contribute to colorectal cancer in Asian populations: a prospective meta-analysis

Glutathione S-transferases (GSTs) are enzymes which expressed in many tissues and play important roles in neutralization of toxic compounds, and protecting hosts against cancer. Among several GSTs, Glutathione S-transferases mu (GSTM) has been drawn attention upon the association with the genetic risk for many types of cancers. But whether the GSTM1 polymorphisms confer the susceptibility to colorectal cancer in Asians has not been well established. We searched the PubMed database with GSTM1, polymorphism and colorectal cancer, attempting to identify the eligible studies. In total, 33 case-control studies in Asian populations with 8502 colorectal cancer patients and 13699 controls were included in the current meta-analysis. The association between the polymorphism and susceptibility to colorectal cancer was evaluated by the odds ratio (OR) and 95% confidence intervals (CI). The pooled meta-analysis suggested that GSTM1 null variant was correlated to the colorectal cancer risk in Asians. There was a marginal heterogeneity among these eligible studies. Nevertheless, cumulative meta-analysis observed a trend of an obvious association between the GSTM1 null genotype and colorectal cancer risk in Asians. In summary, the meta-analysis suggested that GSTM1 null polymorphism confer the susceptibility to colorectal cancer in Asians, especially in Chinese populations.

A systemic review of glutathione S-transferase P1 Ile105Val polymorphism and colorectal cancer risk

OBJECTIVES

To investigate the correlation between glutathione S-transferase P1 (GSTP1) Ile105Val polymorphism and colorectal cancer (CRC) risk.

METHODS

Studies were identified to investigate the association between GSTP1 Ile105Val polymorphism and CRC risk. Systematic computerized searches of the PubMed, Chinese National Knowledge Infrastructure, WANFANG and SinoMed were performed. Summary odds ratios (OR) and 95% confidence intervals (95% CI) were used to measure GSTP1 Ile105Val polymorphisms and CRC risk.

RESULTS

A total of 23 retrospective studies were included in the meta-analysis. During all studies including 6,981 cases and 8,977 controls, sample sizes ranged from 146 to 2,144. Overall, the pooled results revealed that Ile105Val polymorphism was not associated with CRC risk and confused results were found in subgroup analyses. Further meta-analyses were conducted after excluding low-quality studies. GSTP1 Ile105Val is associated with increased risk of CRC limited in studies with matched control. There was no significant heterogeneity in all genetic comparisons, but heterogeneity existed in subgroup analyses of heterozygous and dominant comparisons. The meta-regression analyses indicated that matched controls were the significant factor influencing between-study heterogeneity in all possible influential factors including published year, ethnicity, source of control, sample size, Hardy-Weinberg equilibrium (HWE) in control and matched controls. Sensitivity analysis revealed the pooled ORs were not changed before and after removal of each single study in all genetic comparisons, indicating the robustness of the results.

CONCLUSIONS

GSTP1 Ile105Val might be associated with increased risk of CRC. However, more high-quality case-control studies should be performed to confirm the authenticity of our conclusion.

Fat content and nitrite-curing influence the formation of oxidation products and NOC-specific DNA adducts during in vitro digestion of meat

The effects of fat content and nitrite-curing of pork were investigated on the formation of cytotoxic and genotoxic lipid oxidation products (malondialdehyde, 4-hydroxy-2-nonenal, volatile simple aldehydes), protein oxidation products (protein carbonyl compounds) and NOC-specific DNA adducts (O⁶-carboxy-methylguanine) during invitro digestion. The formation of these products during digestion is suggested to be responsible for the association between red meat and processed meat consumption and colorectal cancer risk. Digestion of uncured pork to which fat was added (total fat content 5 or 20%), resulted in significantly higher lipid and protein oxidation in the mimicked duodenal and colonic fluids, compared to digestion of pork without added fat (1% fat). A higher fat content also significantly favored the formation of O⁶-carboxy-methylguanine in the colon. Nitrite-curing of meat resulted in significantly lower lipid and protein oxidation before and after digestion, while an inconsistent effect on the formation of O⁶-carboxy-methylguanine was observed. The presented results demonstrate that haem-Fe is not solely responsible for oxidation and nitrosation reactions throughout an invitro digestion approach but its effect is promoted by a higher fat content in meat.

Effect of therapeutic plasma exchange on plasma levels of oxidative biomarkers in a patient with thrombotic thrombocytopenic purpura

BACKGROUND

The role of oxidative stress in the initiation and progression of endothelial damage in thrombotic thrombocytopenic purpura (TTP) syndrome has been the subject of much speculation in the recent past.

OBJECTIVES

The aim of this study was to measure the concentration of plasma advanced oxidation protein products (AOPPs), advanced glycation end products (AGEs), and carbonyl groups (CG) as markers of oxidative stress in plasma of a patient with TTP during the course of the disease until recovery and to evaluate the effect of plasmapheresis (PE) on these biomarkers.

MATERIALS AND METHODS

The study consisted of plasma analysis of the patient, and 23 healthy subjects served as controls. In the patient with TTP, AOPP, AGE, and CG analysis was performed before and after each PE at the days +1 (Tα), +2, +4, +6, +10, +9, and +17 after the last plasmapheresis (Tω).

RESULTS

Plasma concentrations of AOPPs were increased in the acute phase of TTP, and at Tα, the patient had AOPPs levels higher than 99°‰ of controls. AOPPs decreased in the recovery phase, and at Tω, their values were between 84° and 85°‰ of controls. No significant difference was found in AOPP levels before and after each PE. No significant differences for AGEs or CG concentrations were found at Tα with respect to the control group, while only a trend was observed for reduction of plasma AGEs after each plasmapheresis.

CONCLUSION

Our data seem to confirm the hypothesis that oxidative stress is a critical component of the pathogenesis of TTP.

Nitrite curing of chicken, pork, and beef inhibits oxidation but does not affect N-nitroso compound (NOC)-specific DNA adduct formation during in vitro digestion

Uncured and nitrite-cured chicken, pork, and beef were used as low, medium, and high sources of heme-Fe, respectively, and exposed to an in vitro digestion model simulating the mouth, stomach, duodenum, and colon. With increasing content of iron compounds, up to 25-fold higher concentrations of the toxic lipid oxidation products malondialdehyde, 4-hydroxy-2-nonenal, and other volatile aldehydes were formed during digestion, together with increased protein carbonyl compounds as measurement of protein oxidation. Nitrite curing of all meats lowered lipid and protein oxidation to the level of oxidation in uncured chicken. Strongly depending on the individual fecal inoculum, colonic digestion of beef resulted in significantly higher concentrations of the NOC-specific DNA adduct O(6)-carboxymethyl-guanine compared to chicken and pork, whereas nitrite curing had no significant effect. This study confirms previously reported evidence that heme-Fe is involved in the epidemiological association between red meat consumption and colorectal cancer, but questions the role of nitrite curing in this association.

Glutathione S-transferase T1 gene polymorphism and colorectal cancer risk: an updated analysis

BACKGROUND AND OBJECTIVE

The association between glutathione S-transferase T1 (GSTT1) gene polymorphisms and colorectal cancer (CRC) susceptibility is still controversial. In order to clarify the effect of GSTT1 genotype on the CRC risk, we carried out an updated meta-analysis of published case-control studies to provide more precise evidence.

METHODS

Two investigators independently searched the databases of Pubmed, EMBASE and China National Knowledge Infrastructure (CNKI) up to October 15, 2012. Crude odds ratios (OR) and 95% confidence intervals (CI) were calculated to investigate the strength of the association in a fixed- or random-effects model depending on statistical heterogeneity.

RESULTS

Forty-six case-control studies with 15,373 colorectal cancer cases and 21,238 controls were included. Overall, the pooled results indicated that GSTT1 null genotype was significantly associated with increased CRC risk (OR=1.21, 95% CI=1.10-1.33). When stratifying for ethnicity and control sources, we also observed positive association between GSTT1 null genotype and increased risk of CRC. When stratifying by the location, we found there was a statistically significant association in the rectal cancer (OR=1.28, 95% CI=1.01-1.64), but not in colon cancer (OR=1.27, 95% CI=0.94-1.73). Subgroup analyses for Dukes stage, histological differentiation of CRC and smoking habit did not reveal any significant differences in genotype distribution. In addition, we observed a strong correlation between increased CRC risk and the combined GSTM1 and GSTT1 null genotype.

CONCLUSIONS

This meta-analysis suggests that the GSTT1 null genotype may contribute to increased risk of colorectal cancer. More well-designed studies based on larger population are needed to confirm our results.

Molecular forms of the insulin-like growth factor-binding protein-2 in patients with colorectal cancer

The components of the insulin-like growth factor (IGF) system and molecules with which they interact are associated with the neoplastic transformation of cells in colorectal cancer. The IGF-binding protein-2 (IGFBP-2) plays a significant role in mitotic stimulation of the cancer cells and its concentration is significantly elevated in tumor states. Little is known about IGFBP-2 at the molecular level and the purpose of this study was to examine the interactions between IGFBP-2 and some other proteins, the fragmentation pattern and posttranslational modifications that might have occurred due to a disease. Results have shown that the amount of monomer IGFBP-2 was 20-30% greater in patients with cancer and the amount of fragmented IGFBP-2 was doubled compared to healthy people, whereas the portion of IGFBP-2 in complex with α2 macroglobulin (α2M) was 2.5 times lower in cancer patients. According to this distribution, IGFBP-2 was not only increasingly synthetized in patients with cancer, but also the amount involved in complexes with α2M was reduced favoring the existence of binary IGFBP-2/IGF complexes, free to leave the circulation. Both IGFBP-2 and α2M were significantly more oxidized in patients with colon cancer than in healthy individuals and α2M was additionally sialylated. It can be speculated that the formation of IGFBP-2/α2M complexes is part of the control mechanism involved in the regulation of IGFBP-2 and, consequently, IGF availability. It also seems that posttranslational modifications are more important factors in determining the amount of IGFBP-2/α2M complexes than the actual quantity of these two proteins.

Glutathione S-transferase M1 polymorphism and colorectal cancer risk in Chinese population

Glutathione S-transferase M1 (GSTM1) polymorphism has been proven to be associated with risks of several cancers. However, previous studies on the association between GSTM1 polymorphism and colorectal cancer risk in Chinese population reported controversial results. We performed a meta-analysis of 13 studies which were identified through the literature search in PubMed and Wanfang databases. The strength of the association between GSTM1 polymorphism and colorectal cancer risk was measured by odds ratio (OR) with corresponding 95% confidence interval (95% CI). Overall, GSTM1 null mutation was significantly associated with a risk of colorectal cancer in Chinese population (OR = 1.37, 95% CI 1.12 to 1.68, P = 0.002). Sensitivity analyses by omitting those studies in turns did not materially alter the overall pooled ORs. The cumulative meta-analyses further showed a trend of an obvious association between GSTM1 null mutation and risk of colorectal cancer in Chinese population as information accumulated by year. The findings from our meta-analysis suggest that GSTM1 null mutation is significantly associated with a risk of colorectal cancer in Chinese population.

The effect of oxoguanine glycosylase 1 rs1052133 polymorphism on colorectal cancer risk in Caucasian population

Human oxoguanine glycosylase 1 (OGG1) is an important part of the base excision repair pathway in the DNA repair. Numerous epidemiological studies have evaluated the association between OGG1 rs1052133 polymorphism and the risk of colorectal cancer, but the results of these studies from the Caucasian population were conflicting. To derive a more precise assessment on the association between OGG1 rs1052133 polymorphism and risk of colorectal cancer in Caucasian population, we performed a meta-analysis. The odds ratios (OR) with 95% confidence intervals (CI) were used to assess the strength of the association. Thirteen case-control studies with a total of 4,103 cases and 5,400 controls were finally included into the meta-analysis. Meta-analysis of all 13 studies showed that OGG1 rs1052133 polymorphism was significantly associated with the risk of colorectal cancer in Caucasian population (Cys versus Ser OR = 1.20, 95% CI = 1.03-1.39, P = 0.02; CysCys versus SerSer OR = 1.44, 95% CI = 1.04-2.00, P = 0.03; CysCys versus SerSer/SerCys OR = 1.39, 95% CI = 1.15-1.67, P = 0.0005). In the sensitivity analysis, omitting each study one at a time had no obvious influence on the pooled OR, which confirmed the stability of meta-analysis. The meta-analysis suggests that OGG1 rs1052133 polymorphism is significantly associated with the risk of colorectal cancer in Caucasian population.

Tumor site- and stage-specific associations between allelic variants of glutathione S-transferase and DNA-repair genes and overall survival in colorectal cancer patients receiving 5-fluorouracil-based chemotherapy

Introduction

Our retrospective cohort study investigated the effect of tumor site and stage on the associations between the allelic variants of glutathione S-transferase (GST) and DNA-repair genes and overall survival (OS) in CRC patients treated with 5-fluorouracil (5-FU)-based adjuvant chemotherapy.

Material and Methods

We genotyped GSTM1, GSTT1, GSTP1 Ile105Val, XRCC1 Arg399Gln, XRCC3 Thr241Met, and XPD Lys751Gln in 491 CRC patients between 1995 and 2001. A Cox proportional-hazards model was used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) for the relationships between the allelic variants and OS. Survival analyses were performed for each allelic variant by using the log-rank test and Kaplan-Meier analysis.

Results

The CRC patients with the XPD Gln allelic variants had poorer survival than patients with the Lys/Lys genotype (HR  = 1.38, 95% CI  = 1.02–1.87), and rectal cancer patients had the poorest survival among them (HR  = 1.87, 95% CI  = 1.18–2.95). A significantly shorter OS was observed among stage II/III colon cancer patients with the XRCC1 Gln allelic variants (HR  = 1.69, 95% CI  = 1.06–2.71), compared to those with XRCC1 Arg/Arg genotype. In the combined analysis of the XRCC1 and XPD genes patients with stage II/III tumors, the poorest OS occurred in colon cancer patients with the XRCC1 Gln and XPD Gln allelic variants (HR  = 2.60, 95% CI  = 1.19–5.71) and rectal cancer patients with the XRCC1 Arg/Arg and XPD Gln allelic variants (HR  = 2.77, 95% CI  = 1.25–6.17).

Conclusion

The XPD and XRCC1 allelic variants may be prognostic markers for CRC patients receiving 5-FU based chemotherapy. The contributions of the XPD and XRCC1 allelic variants to OS are tumor site- and/or stage-dependent.

Clinical and research markers of oxidative stress in chronic kidney disease

CONTEXT

Kidney-related pathologies have increasing prevalence rates, produce a considerable financial burden, and are characterized by elevated levels of oxidative stress (OS).

OBJECTIVE

This review examines relationships between chronic kidney disease (CKD) and markers of OS and antioxidant status (AS).

METHODS

A systematic review of MEDLINE-indexed clinical trials, randomized controlled trials and comparative studies that examined OS and AS was performed.

RESULTS AND CONCLUSION

Several markers emerged as well-suited indicators of OS and AS in CKD: malondialdehyde, F2-isoprostanes, lipid hydroperoxides, asymmetric dimethylarginine, 8-oxo-7,8-dihydro-2'-deoxyguanosine, protein carbonyls, advanced oxidation protein products and glutathione-related activity.

Association between polymorphisms of glutathione S-transferase genes (GSTM1, GSTP1 and GSTT1) and breast cancer risk in a sample Iranian population

Aim: Genetic and environmental factors are risk factors for breast cancer. Our aim was to investigate the associations between genetic polymorphism of GST genes (GSTM1, GSTT1 and GSTP1) and susceptibility to breast cancer in an Iranian population. Materials & methods: This case–control study was carried out on 134 patients with breast cancer and 152 healthy, cancer-free women. GSTP1 polymorphism was determined using tetra-primer amplification refractory mutation system PCR assay and GSTM1 and GSTT1 were genotyped by a multiplex PCR. Results: We found that the GSTM1 null genotype is a risk factor for predisposition to breast cancer (odds ratio [OR] = 2.01; 95% CI = 1.78–3.45; p = 0.010). No significant difference was found between the groups regarding GSTT1 null genotype (p > 0.05). The GSTP1 Ile/Val and Val/Val genotypes were associated with breast cancer risk (OR = 3.29; 95% CI = 1.84–5.91; p < 0.0001 and OR = 20.68; 95% CI = 5.66–75.60; p < 0.0001, respectively). Conclusion: In summary, GSTM1 and GSTP1, but not GSTT1 genetic polymorphisms are associated with increased risk of breast cancer in our population.

Oxidative protein damage with carbonyl levels and nitrotyrosine expression after chemotherapy in bone marrow transplantation patients

Protein oxidation is defined as the covalent modification ofa protein, induced either directly by reactive oxygen species/reactive nitrogen species or indirectly by reaction with secondary by-products of oxidative stress. Protein carbonyls are the most commonly measured products of protein oxidation. Additionally, nitrotyrosine is a product of tyrosine nitration mediated by reactive nitrogen species such as peroxynitrite anion and nitrogen dioxide. Samples were collected before the preparative regimen (10 days before transplantation; day –10), on transplantation day (day 0), and after transplantation (days 7, 14, and 28) from 16 pediatric allogeneic hematopoietic stem cell transplantation (HSCT) patients.The erythrocyte 3-nitrotyrosine expression was shown to be significantly increased after chemotherapy. In accordance, the mean plasma carbonyl levels on days 14 and 28 were significantly higher than on the other days. High dose chemotherapy applied in the preparative regimen of HSCT may be responsible for this long-term oxidation of plasma proteins. These results show that high-dose chemotherapy resulted in protein oxidation both in plasma and in erythrocytes in HSCT patients.

Peripheral oxidative damage in early-stage mood disorders: a nested population-based case-control study

Systemic toxicity is a relevant dimension of pathophysiology in bipolar disorder, and oxidative damage is one potential link between central and peripheral pathology. Although there is mounting evidence that chronic bipolar disorder is associated with oxidative stress, studies in the early stages of bipolar disorder are scarce, and heavily reliant on clinical in lieu of population studies. The objective of this study was to confirm leading hypotheses about the role of oxidative damage in bipolar disorder. To that end, we nested a case-control study in a population-based study of young adults aged 18-24 yr. After an initial psychopathology screen, all people with a lifetime history of (hypo)mania and matched controls underwent a structured diagnostic interview. This yielded a sample of 231 participants, in whom we measured serum protein carbonyl content (PCC) and thiobarbituric acid reactive substances (TBARS). People with bipolar disorder had higher PCC levels than healthy subjects. Those with major depression were not different from control subjects in either PCC or TBARS levels. Both bipolar disorder and major depression were associated with higher PCC levels in the a priori regression model controlling for possible confounders. These findings indicate that protein oxidative damage is present from early stages and can be seen as a sign of early illness activity in mood disorders.

Prolonged depletion of antioxidant capacity after ultraendurance exercise

PURPOSE

The purpose of this study was to examine the short- and long-term (up to 1 month) effects of an ultraendurance running event on redox homeostasis.

METHODS

Markers of oxidative stress and antioxidant capacity in peripheral blood were assessed after a single-stage 233-km (143 miles) running event. Samples were collected from nine men (mean±SD: age=46.1±5.3 yr, body mass index=24.9±2.3 kg·m⁻², maximal oxygen uptake=56.3±3.3 mL·kg⁻¹·min⁻¹). Peripheral blood mononuclear cells were assayed for nonspecific DNA damage (frank strand breaks) and damage to DNA caused specifically by oxidative stress (formamidopyrimidine DNA glycosylase-dependent damage). Protein carbonylation and lipid peroxidation were assessed in plasma. Reduced glutathione (GSH) was measured in whole blood.

RESULTS

Peripheral blood mononuclear cell frank strand breaks were elevated above baseline at 24 h after the race (P<0.001). Formamidopyrimidine DNA glycosylase-dependent oxidative DNA damage was increased immediately after the race (P<0.05). Protein carbonylation remained elevated for 7 d after the race (P<0.04), whereas lipid peroxidation was increased for 24 h (P<0.05) and fell below baseline 28 d later (P<0.05). GSH, a measure of antioxidant capacity, also showed a biphasic response, increasing by one-third after the race (P<0.01) and falling to two-thirds of baseline levels 24 h later (P<0.001). GSH remained depleted to approximately one-third of prerace values 28 d after the race (P<0.01).

CONCLUSIONS

Ultraendurance exercise causes oxidative stress, which persists for one calendar month depending on the specific biomarker examined. These results suggest that ultraendurance events are associated with a prolonged period of reduced protection against oxidative stress.

GSTM1 and GSTT1 polymorphisms and colorectal cancer risk in Chinese population: a meta-analysis

PURPOSE

Studies investigating the associations between GSTM1 and GSTT1 polymorphisms and colorectal cancer (CRC) risk in Chinese population have reported controversial results. Thus, a meta-analysis was performed.

METHODS

Four hundred and seven relevant records were identified through a literature search up to September 7, 2011, and 19 studies were finally included, involving a total of 3,130 CRC cases and 6,423 controls. Subgroup analyses were performed by language and study design. Statistical analysis was performed with the software programs Review Manager (version 5.1.2) and STATA (version 11.0).

RESULTS

For the GSTM1 polymorphism, the null genotype of GSTM1 was not associated with CRC risk in Chinese population (OR = 1.12, 95% CI = 0.97-1.28). Similar associations were found for GSTT1 polymorphism (OR = 1.10, 95% CI = 0.94-1.29) and the dual null genotype of GSTM1/GSTT1 (OR = 1.26, 95% CI = 0.93-1.71). For subgroup analyses, studies published in English and population-based studies further identified these associations for the three aspects above in Chinese population.

CONCLUSIONS

This meta-analysis suggests that the null genotypes of GSTM1 and GSTT1 and the dual null genotype of GSTM1/GSTT1 were all not risk factors in CRC in Chinese population.

Null genotype of glutathione S-transferase Tl contributes to colorectal cancer risk in the Asian population: a meta-analysis

BACKGROUND AND AIM

Previous studies investigating the association between the glutathione S-transferase Tl (GSTT1) null genotype and colorectal cancer (CRC) risk in the Asian population have reported controversial results. Thus, a meta-analysis was performed to clarify the effect of the GSTT1 null genotype on CRC risk in the Asian population.

METHODS

A comprehensive study was conducted, and 12 case-control studies were finally included, involving a total of 4517 CRC cases and 6607 controls. Subgroup analyses were performed by the sample size.

RESULTS

A meta-analysis of all 12 studies showed that the GSTT1 null genotype was significantly associated with an increased CRC risk in the Asian population (odds ratio [OR] = 1.10, 95% confidence interval [CI] = 1.02-1.19, the P-value of the OR [P(OR)] = 0.02, the value of the heterogeneity analysis [I(2)] = 42%). A more obvious association was observed after the heterogeneity was eliminated by excluding one study (OR = 1.15, 95% CI: 1.06-1.25, P(OR) = 0.001, I(2) = 0%). This association was further identified by both subgroup analyses and a sensitivity analysis.

CONCLUSIONS

This meta-analysis suggests that the GSTT1 null genotype contributes to an increased colorectal cancer risk in the Asian population.

Carbonyl group serum levels are associated with CD38 expression in patients with B chronic lymphocytic leukemia

OBJECTIVES

To evaluate carbonyl groups (CG) serum levels in B-chronic lymphocytic leukemia (B-CLL) patients.

DESIGN AND METHODS

CG serum levels were assessed in 48 B-CLL patients and in 30 control subjects.

RESULTS

CG were increased in B-CLL patients. We found a positive correlation between CG with CD38 expression and a negative correlation with ZAP 70 expression.

CONCLUSIONS

B-CLL patients displayed an unbalance of the oxidative stress. CG serum levels could be considered as a prognostic factor in B-CLL.