Cytoprotective and regulatory functions of glutathione S-transferases in cancer cell proliferation and cell death

The role of glutamate and glutamine metabolism and related transporters in nerve cells

BACKGROUND

Glutamate and glutamine are the most abundant amino acids in the blood and play a crucial role in cell survival in the nervous system. Various transporters found in cell and mitochondrial membranes, such as the solute carriers (SLCs) superfamily, are responsible for maintaining the balance of glutamate and glutamine in the synaptic cleft and within cells. This balance affects the metabolism of glutamate and glutamine as non-essential amino acids.

AIMS

This review aims to provide an overview of the transporters and enzymes associated with glutamate and glutamine in neuronal cells.

DISCUSSION

We delve into the function of glutamate and glutamine in the nervous system by discussing the transporters involved in the glutamate-glutamine cycle and the key enzymes responsible for their mutual conversion. Additionally, we highlight the role of glutamate and glutamine as carbon and nitrogen donors, as well as their significance as precursors for the synthesis of reduced glutathione (GSH).

CONCLUSION

Glutamate and glutamine play a crucial role in the brain due to their special effects. It is essential to focus on understanding glutamate and glutamine metabolism to comprehend the physiological behavior of nerve cells and to treat nervous system disorders and cancer.

Platinum-based targeted chemotherapies and reversal of cisplatin resistance in non-small cell lung cancer (NSCLC)

Lung cancer is the one of the most prevalent cancer in the world. It kills more people from cancer than any other cause and is especially common in underdeveloped nations. With 1.2 million instances, it is also the most prevalent cancer in men worldwide, making about 16.7% of the total cancer burden. Surgery is the main form of curative treatment for early-stage lung cancer. However, the majority of patients had incurable advanced non-small cell lung cancer (NSCLC) recurrence after curative purpose surgery, which is indicative of the aggressiveness of the illness and the dismal outlook. The gold standard of treatment for NSCLC patients includes drug targeting of specific mutated genes drive in development of lung cancer. Furthermore, patients with advanced NSCLC and those with early-stage illness needing adjuvant therapy should use cisplatin as it is the more active platinum drug. So, this review encompasses the non-small cell lung cancer microenvironment, treatment approaches, and use of cisplatin as a first-line regimen for NSCLC, its mechanism of action, cisplatin resistance in NSCLC and also the prevention strategies to revert the drug resistance.

The Role of Cytokines in Activation of Tumour-promoting Pathways and Emergence of Cancer Drug Resistance

Scientists are constantly researching and launching potential chemotherapeutic agents as an irreplaceable weapon to fight the battle against cancer. Despite remarkable advancement over the past several decades to wipe out cancer through early diagnosis, proper prevention, and timely treatment, cancer is not ready to give up and leave the battleground. It continuously tries to find some other way to give a tough fight for its survival, either by escaping from the effect of chemotherapeutic drugs or utilising its own chemical messengers like cytokines to ensure resistance. Cytokines play a significant role in cancer cell growth and progression, and the present article highlights their substantial contribution to mechanisms of resistance toward therapeutic drugs. Multiple clinical studies have even described the importance of specific cytokines released from cancer cells as well as stromal cells in conferring resistance. Herein, we discuss the different mechanism behind drug resistance and the crosstalk between tumor development and cytokines release and their contribution to showing resistance towards chemotherapeutics. As a part of this review, different approaches to cytokines profile have been identified and employed to successfully target new evolving mechanisms of resistance and their possible treatment options.

Epigenetic regulation in lung cancer

Lung cancer is indeed a major cause of cancer-related deaths worldwide. The development of tumors involves a complex interplay of genetic, epigenetic, and environmental factors. Epigenetic mechanisms, including DNA methylation (DNAm), histone modifications, and microRNA expression, play a crucial role in this process. Changes in DNAm patterns can lead to the silencing of important genes involved in cellular functions, contributing to the development and progression of lung cancer. MicroRNAs and exosomes have also emerged as reliable biomarkers for lung cancer. They can provide valuable information about early diagnosis and treatment assessment. In particular, abnormal hypermethylation of gene promoters and its effects on tumorigenesis, as well as its roles in the Wnt signaling pathway, have been extensively studied. Epigenetic drugs have shown promise in the treatment of lung cancer. These drugs target the aberrant epigenetic modifications that are involved in the development and progression of the disease. Several factors have been identified as drug targets in non-small cell lung cancer. Recently, combination therapy has been discussed as a successful strategy for overcoming drug resistance. Overall, understanding the role of epigenetic mechanisms and their targeting through drugs is an important area of research in lung cancer treatment.

Overexpression of Glutathione S-Transferases in Human Diseases: Drug Targets and Therapeutic Implications

Glutathione S-transferases (GSTs) are a major class of phase II metabolic enzymes. Besides their essential role in detoxification, GSTs also exert diverse biological activities in the occurrence and development of various diseases. In the past few decades, much research interest has been paid to exploring the mechanisms of GST overexpression in tumor drug resistance. Correspondingly, many GST inhibitors have been developed and applied, solely or in combination with chemotherapeutic drugs, for the treatment of multi-drug resistant tumors. Moreover, novel roles of GSTs in other diseases, such as pulmonary fibrosis and neurodegenerative diseases, have been recognized in recent years, although the exact regulatory mechanisms remain to be elucidated. This review, firstly summarizes the roles of GSTs and their overexpression in the above-mentioned diseases with emphasis on the modulation of cell signaling pathways and protein functions. Secondly, specific GST inhibitors currently in pre-clinical development and in clinical stages are inventoried. Lastly, applications of GST inhibitors in targeting cell signaling pathways and intracellular biological processes are discussed, and the potential for disease treatment is prospected. Taken together, this review is expected to provide new insights into the interconnection between GST overexpression and human diseases, which may assist future drug discovery targeting GSTs.

Insights on the Role of Polyphenols in Combating Cancer Drug Resistance

Chemotherapy resistance is still a serious problem in the treatment of most cancers. Many cellular and molecular mechanisms contribute to both inherent and acquired drug resistance. They include the use of unaffected growth-signaling pathways, changes in the tumor microenvironment, and the active transport of medicines out of the cell. The antioxidant capacity of polyphenols and their potential to inhibit the activation of procarcinogens, cancer cell proliferation, metastasis, and angiogenesis, as well as to promote the inhibition or downregulation of active drug efflux transporters, have been linked to a reduced risk of cancer in epidemiological studies. Polyphenols also have the ability to alter immunological responses and inflammatory cascades, as well as trigger apoptosis in cancer cells. The discovery of the relationship between abnormal growth signaling and metabolic dysfunction in cancer cells highlights the importance of further investigating the effects of dietary polyphenols, including their ability to boost the efficacy of chemotherapy and avoid multidrug resistance (MDR). Here, it is summarized what is known regarding the effectiveness of natural polyphenolic compounds in counteracting the resistance that might develop to cancer drugs as a result of a variety of different mechanisms.

Organic Semiconducting Nanoparticles for Biosensor: A Review

Highly bio-compatible organic semiconductors are widely used as biosensors, but their long-term stability can be compromised due to photo-degradation and structural instability. To address this issue, scientists have developed organic semiconductor nanoparticles (OSNs) by incorporating organic semiconductors into a stable framework or self-assembled structure. OSNs have shown excellent performance and can be used as high-resolution biosensors in modern medical and biological research. They have been used for a wide range of applications, such as detecting small biological molecules, nucleic acids, and enzyme levels, as well as vascular imaging, tumor localization, and more. In particular, OSNs can simulate fine particulate matters (PM_2.5, indicating particulate matter with an aerodynamic diameter less than or equal to 2.5 μm) and can be used to study the biodistribution, clearance pathways, and health effects of such particles. However, there are still some problems that need to be solved, such as toxicity, metabolic mechanism, and fluorescence intensity. In this review, based on the structure and design strategies of OSNs, we introduce various types of OSNs-based biosensors with functional groups used as biosensors and discuss their applications in both in vitro and in vivo tracking. Finally, we also discuss the design strategies and potential future trends of OSNs-based biosensors. This review provides a theoretical scaffold for the design of high-performance OSNs-based biosensors and highlights important trends and future directions for their development and application.

Age-related cataract: GSTP1 ubiquitination and degradation by Parkin inhibits its anti-apoptosis in lens epithelial cells

PURPOSE

Oxidative stress-induced apoptosis of lens epithelial cells (LECs) contributes to the pathogenesis of age-related cataract (ARC). The purpose of this research is to underlie the potential mechanism of E3 ligase Parkin and its oxidative stress-associated substrate in cataractogenesis.

METHODS

The central anterior capsules were obtained from patients with ARC, Emory mice, and corresponding controls. SRA01/04 cells were exposed to H₂O₂ combined with cycloheximide (a translational inhibitor), MG-132 (a proteasome inhibitor), chloroquine (an autophagy inhibitor), Mdivi-1 (a mitochondrial division inhibitor), respectively. Co-immunoprecipitation was employed to detect protein-protein interactions and ubiquitin-tagged protein products. Levels of proteins and mRNA were evaluated by western blotting and quantitative RT-PCR assays.

RESULTS

Glutathione-S-transferase P1 (GSTP1) was identified as a novel Parkin substrate. Compared with corresponding controls, GSTP1 was significantly decreased in the anterior lens capsules obtained from human cataracts and Emory mice. Similarly, GSTP1 was declined in H₂O₂-stimulated SRA01/04 cells. Ectopic expression of GSTP1 mitigated H₂O₂-induced apoptosis, whereas silencing GSTP1 aggregated apoptosis. In addition, H₂O₂ stimulation and Parkin overexpression could promote the degradation of GSTP1 through the ubiquitin-proteasome system, autophagy-lysosome pathway, and mitophagy. After co-transfection with Parkin, the non-ubiquitinatable GSTP1 mutant maintained its anti-apoptotic function, while wildtype GSTP1 failed. Mechanistically, GSTP1 might promote mitochondrial fusion through upregulating Mitofusins 1/2 (MFN1/2).

CONCLUSION

Oxidative stress induces LECs apoptosis via Parkin-regulated degradation of GSTP1, which may provide potential targets for ARC therapy.

Association of Clinical Aspects and Genetic Variants with the Severity of Cisplatin-Induced Ototoxicity in Head and Neck Squamous Cell Carcinoma: A Prospective Cohort Study

Background: Cisplatin (CDDP) is a major ototoxic chemotherapy agent for head and neck squamous cell carcinoma (HNSCC) treatment. Clinicopathological features and genotypes encode different stages of CDDP metabolism, as their coexistence may influence the prevalence and severity of hearing loss. Methods: HNSCC patients under CDDP chemoradiation were prospectively provided with baseline and post-treatment audiometry. Clinicopathological features and genetic variants encoding glutathione S-transferases (GSTT1, GSTM1, GSTP1), nucleotide excision repair (XPC, XPD, XPF, ERCC1), mismatch repair (MLH1, MSH2, MSH3, EXO1), and apoptosis (P53, CASP8, CASP9, CASP3, FAS, FASL)-related proteins were analyzed regarding ototoxicity. Results: Eighty-nine patients were included, with a cumulative CDDP dose of 260 mg/m2. Moderate/severe ototoxicity occurred in 26 (29%) patients, particularly related to hearing loss at frequencies over 3000 Hertz. Race, body-mass index, and cumulative CDDP were independent risk factors. Patients with specific isolated and combined genotypes of GSTM1, GSTP1 c.313A>G, XPC c.2815A>C, XPD c.934G>A, EXO1 c.1762G>A, MSH3 c.3133A>G, FASL c.-844A>T, and P53 c.215G>C SNVs had up to 32.22 higher odds of presenting moderate/severe ototoxicity. Conclusions: Our data present, for the first time, the association of combined inherited nucleotide variants involved in CDDP efflux, DNA repair, and apoptosis with ototoxicity, which could be potential predictors in future clinical and genomic models.

A Review of the GSTM1 Null Genotype Modifies the Association between Air Pollutant Exposure and Health Problems

Air pollution is one of the significant environmental risks known as the cause of premature deaths. It has deleterious effects on human health, including deteriorating respiratory, cardiovascular, nervous, and endocrine functions. Exposure to air pollution stimulates reactive oxygen species (ROS) production in the body, which can further cause oxidative stress. Antioxidant enzymes, such as glutathione S-transferase mu 1 (GSTM1), are essential to prevent oxidative stress development by neutralizing excess oxidants. When the antioxidant enzyme function is lacking, ROS can accumulate and, thus, cause oxidative stress. Genetic variation studies from different countries show that GSTM1 null genotype dominates the GSTM1 genotype in the population. However, the impact of the GSTM1 null genotype in modifying the association between air pollution and health problem is not yet clear. This study will elaborate on GSTM1's null genotype role in modifying the relationship between air pollution and health problems.

Myricetin as a Potential Adjuvant in Chemotherapy: Studies on the Inhibition of Human Glutathione Transferase A1–1

Glutathione transferases (GSTs) are a family of Phase II detoxification enzymes that are involved in the development of multi-drug resistance (MDR) phenomena toward chemotherapeutic agents. GST inhibitors are considered candidate compounds able to chemomodulate and reverse MDR. The natural flavonoid myricetin (MYR) has been shown to exhibit a wide range of pharmacological functions, including antitumor activity. In the present work, the interaction of MYR with human glutathione transferase A1–1 (hGSTA1–1) was investigated by kinetics inhibition analysis and molecular modeling studies. The results showed that MYR binds with high affinity to hGSTA1–1 (IC50 2.1 ± 0.2 μΜ). It functions as a non-competitive inhibitor towards the electrophile substrate 1-chloro−2,4-dinitrobenzene (CDNB) and as a competitive inhibitor towards glutathione (GSH). Chemical modification studies with the irreversible inhibitor phenethyl isothiocyanate (PEITC), in combination with in silico molecular docking studies allowed the prediction of the MYR binding site. MYR appears to bind at a distinct location, partially overlapping the GSH binding site (G-site). The results of the present study show that MYR is a potent inhibitor of hGSTA1–1 that can be further exploited towards the development of natural, safe, and effective GST-targeted cancer chemosensitizers.

Antioxidant and pro-oxidant phytochemicals in ultrasound and microwave assisted extracts from hop cones: a statistical modelling approach

The present study investigated the relationships between different green extracts from hop cones (HGEs) and their cytoprotective/cytotoxic effects on human cultured colonocytes, using a multivariate statistical approach. HGEs were obtained by ultrasound (US) and microwave (MW) assisted extraction, using food grade solvents (ethanol and ethanol : water = 50 : 50 mixture). Their chemical fingerprinting showed the presence of 21 bioactive compounds belonging to the classes of polyphenols, prenylcalcones and floroacylglucinols, which were more abundant in MW ethanolic extracts. All the extracts, except for the US hydroalcoholic one, exerted a cytotoxic effect in a dose-dependent manner. HGEs did not alter the cellular redox status at low doses, while at the highest concentrations considered they displayed a pro-oxidant or antioxidant activity. Chemometric analysis revealed the compounds most correlated with cellular toxicity and/or ROS production and that the differences observed in Caco2 cells could be adequately explained by 2D statistical models including inhibitor-promoting agent pairs.

Association Between the Individual and Combined Effects of the GSTM1 and GSTT1 Polymorphisms and Risk of Leukemia: A Meta-Analysis

Background: Fourteen meta-analyses reported the individual effects of the GSTM1 and GSTT1 polymorphisms on leukemia risk. However, over 40 studies were not included in previously published meta-analyses. Moreover, one key aspect was that previous meta-analyses did not conduct the false-positive test on the aforementioned issues. Furthermore, previous meta-analyses did not observe the combined effects of GSTM1 present/null and GSTT1 present/null polymorphism with leukemia risk. Therefore, we conducted the current study to further analyze these associations.

Objectives: This study aimed to investigate the association between the individual and combined effects of the GSTM1 present/null and GSTT1 present/null polymorphisms and the risk of leukemia.

Methods: A meta-analysis was performed applying Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines. Moreover, false-positive report probability (FPRP) and Bayesian false discovery probability (BFDP) were applied to investigate the false-positive results.

Results: The individual GSTM1 and GSTT1 null genotypes and combined effects of the two genes were associated with a significantly increased leukemia risk in overall and several subgroup analyses, such as Asians, Caucasians, and so on. Then, further analysis was conducted using FPRP and BFDP. Significant associations were considered as “positive” results on the GSTM1 null genotype with leukemia risk in overall populations (FPRP < 0.001 and BFDP = 0.006), Asians (FPRP < 0.001 and BFDP < 0.001), and East Asian population (FPRP < 0.001 and BFDP = 0.002). For the GSTT1 null genotype, significant associations were regarded “positive” results in overall populations, acute myeloid leukemia (AML), Asians, and East Asian population. For the combined effects of the GSTM1 and GSTT1 polymorphisms, significant associations were also considered “positive” results in the overall analysis of Asians, Indians, and East Asian population.

Conclusion: This study strongly indicates that the individual GSTM1 and GSTT1 null genotypes and combined effects of the two genes are associated with increased leukemia risk in Asians, especially in the East Asian population; the GSTT1 null genotype is associated with increased AML risk; the combined effects of the two genes are associated with increased leukemia risk in Indians.

Curzerene suppresses progression of human glioblastoma through inhibition of glutathione S-transferase A4

Aims

Glioblastoma is the central nervous system tumor with the highest mortality rate, and the clinical effectiveness of chemotherapy is low. Curzerene can inhibit the progression of non‐small‐cell lung cancer, but its role in glioma has not been reported. The purpose of this study was to clarify the effect of curzerene on glioma progression and further explore its potential mechanism.

Methods

The expression of glutathione S‐transferase A4 (GSTA4) in glioblastoma and the effect of curzerene on the expression of GSTA4 and matrix metalloproteinase 9 and the activation of the mTOR pathway were detected by Western blotting and RT‐PCR, and the effects of curzerene treatment on glioma malignant character were detected by cell biological assays. The in vivo antitumor effects of curzerene were analyzed in a nude mouse xenograft model.

Results

Curzerene was found to inhibit the expression of GSTA4 mRNA and protein in U251 and U87 glioma cells, and this effect correlated with a downregulation of the proliferation of these cells in a time‐ and dose‐dependent manner. Invasion and migration were also inhibited, and curzerene treatment correlated with induction of apoptosis. Curzerene inhibited the activation of the mTOR pathway and the expression of matrix metalloproteinase 9, and it correlated with increased 4‐hydroxynonenal levels. In vivo, curzerene was found to significantly inhibit tumor growth in nude mice and to prolong the survival time of tumor‐bearing nude mice.

Conclusion

In conclusion, inhibition of GSTA4 correlates with positive outcomes in glioma models, and thus, this molecule is a candidate drug for the treatment of glioma.

GSTP1 and GSTM3 Variant Alleles Affect Susceptibility and Severity of COVID-19

Based on the premise that oxidative stress plays an important role in severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection, we speculated that variations in the antioxidant activities of different members of the glutathione S-transferase family of enzymes might modulate individual susceptibility towards development of clinical manifestations in COVID-19. The distribution of polymorphisms in cytosolic glutathione S-transferases GSTA1, GSTM1, GSTM3, GSTP1 (rs1695 and rs1138272), and GSTT1 were assessed in 207 COVID-19 patients and 252 matched healthy individuals, emphasizing their individual and cumulative effect in disease development and severity. GST polymorphisms were determined by appropriate PCR methods. Among six GST polymorphisms analyzed in this study, GSTP1 rs1695 and GSTM3 were found to be associated with COVID-19. Indeed, the data obtained showed that individuals carrying variant GSTP1-Val allele exhibit lower odds of COVID-19 development (p = 0.002), contrary to carriers of variant GSTM3-CC genotype which have higher odds for COVID-19 (p = 0.024). Moreover, combined GSTP1 (rs1138272 and rs1695) and GSTM3 genotype exhibited cumulative risk regarding both COVID-19 occurrence and COVID-19 severity (p = 0.001 and p = 0.025, respectively). Further studies are needed to clarify the exact roles of specific glutathione S-transferases once the SARS-CoV-2 infection is initiated in the host cell.

Implications of glutathione-S transferase P1 in MAPK signaling as a CRAF chaperone: In memory of Dr. Irving Listowsky

Glutathione-S transferase P1 (GSTP1) is one of the glutathione-S transferase isozymes that belong to a family of phase II metabolic isozymes. The unique feature of GSTP1 compared with other GST isozymes is its relatively high expression in malignant tissues. Thus, clinically, GSTP1 serves as a tumor marker and as a refractory factor against certain types of anticancer drugs through its primary function as a detoxifying enzyme. Additionally, recent studies have identified a chaperone activity of GSTP1 involved in the regulation the function of various intracellular proteins, including factors of the growth signaling pathway. In this review, we will first describe the function of GSTP1 and then extend the details onto its role in the mitogen-activated protein kinase signal pathway, referring to the results of our recent study that proposed a novel autocrine signal loop formed by the CRAF/GSTP1 complex in mutated KRAS and BRAF cancers. Finally, the possibilities of new therapeutic approaches for these cancers by targeting this complex will be discussed.

Still no Rest for the Reductases: Ribonucleotide Reductase (RNR) Structure and Function: An Update

Herein we present a multidisciplinary discussion of ribonucleotide reductase (RNR), the essential enzyme uniquely responsible for conversion of ribonucleotides to deoxyribonucleotides. This chapter primarily presents an overview of this multifaceted and complex enzyme, covering RNR's role in enzymology, biochemistry, medicinal chemistry, and cell biology. It further focuses on RNR from mammals, whose interesting and often conflicting roles in health and disease are coming more into focus. We present pitfalls that we think have not always been dealt with by researchers in each area and further seek to unite some of the field-specific observations surrounding this enzyme. Our work is thus not intended to cover any one topic in extreme detail, but rather give what we consider to be the necessary broad grounding to understand this critical enzyme holistically. Although this is an approach we have advocated in many different areas of scientific research, there is arguably no other single enzyme that embodies the need for such broad study than RNR. Thus, we submit that RNR itself is a paradigm of interdisciplinary research that is of interest from the perspective of the generalist and the specialist alike. We hope that the discussions herein will thus be helpful to not only those wanting to tackle RNR-specific problems, but also those working on similar interdisciplinary projects centering around other enzymes.

Protective Effects of Antioxidant Chlorophyllin in Chemically Induced Breast Cancer Model In vivo

Glutathione-related enzymes belong to the protection mechanism of the cells against harmful oxidative damage and chemicals. Glutathione S-transferase (GST) is frequently over-expressed in various cancer cells and is involved in drug resistance. Chlorophyllin is an antioxidant molecule interfering with the GST P1-1 activity. The purpose of this study is to evaluate the short- and long-term protective effects of chlorophyllin as an antioxidant molecule on DNA damage, antioxidant enzyme activities, trace elements, and minerals in chemically induced breast cancer model in vivo. In our study, N-methyl-N-nitrosourea (MNU) was used for inducing breast carcinogenesis in female Sprague-Dawley rats. A total of 36 rats were divided into groups as short term and long term. Each group was divided into four sub-groups as control group received physiological saline solution (n = 3), Chl group (n = 5) received chlorophyllin, MNU group (n = 5) was administered MNU, and Chl + MNU group (n = 5) was treated with both chlorophyllin and MNU. Results illustrated that chlorophyllin had a significant anti-genotoxic effect in the short term, and glutathione-related enzyme activities were protected by chlorophyllin treatment in MNU-induced breast cancer model. Additionally, MNU administration impaired mineral and trace element levels including Na, Mg, K, Fe, Zn, and Co in the liver, kidney, spleen, heart, and tumor tissues; however, adverse effects of MNU were recovered upon chlorophyllin treatment in the indicated tissues of the rats. In conclusion, chlorophyllin can be used as an antioxidant molecule to ameliorate adverse effects of MNU by enhancing antioxidant enzyme activities and regulating trace element and mineral balance in several organs and tumor tissue in the breast cancer model.

The Cytotoxic Effect of Copper (II) Complexes with Halogenated 1,3-Disubstituted Arylthioureas on Cancer and Bacterial Cells

A series of eight copper (II) complexes with 3-(4-chloro-3-nitrophenyl)thiourea were designed and synthesized. The cytotoxic activity of all compounds was assessed in three human cancer cell lines (SW480, SW620, PC3) and human normal keratinocytes (HaCaT). The complexes 1, 3, 5, 7 and 8 were cytotoxic to the studied tumor cells in the low micromolar range, without affecting the normal cells. The complexes 1, 3, 7 and 8 induced lactate dehydrogenase (LDH) release in all cancer cell lines, but not in the HaCaT cells. They provoked early apoptosis in pathological cells, especially in SW480 and PC3 cells. The ability of compounds 1, 3, 7 and 8 to diminish interleukin-6 (IL-6) concentration in a cell was established. For the first time, the influence of the most promising Cu (II) complexes on intensities of detoxifying and reactive oxygen species (ROS) scavenging the enzymes of tumor cells was studied. The cytotoxic effect of all copper (II) conjugates against standard and hospital bacterial strains was also proved.

New Advances in the Research of Resistance to Neoadjuvant Chemotherapy in Breast Cancer

Breast cancer has an extremely high incidence in women, and its morbidity and mortality rank first among female tumors. With the increasing development of medicine today, the clinical application of neoadjuvant chemotherapy has brought new hope to the treatment of breast cancer. Although the efficacy of neoadjuvant chemotherapy has been confirmed, drug resistance is one of the main reasons for its treatment failure, contributing to the difficulty in the treatment of breast cancer. This article focuses on multiple mechanisms of action and expounds a series of recent research advances that mediate drug resistance in breast cancer cells. Drug metabolizing enzymes can mediate a catalytic reaction to inactivate chemotherapeutic drugs and develop drug resistance. The drug efflux system can reduce the drug concentration in breast cancer cells. The combination of glutathione detoxification system and platinum drugs can cause breast cancer cells to be insensitive to drugs. Changes in drug targets have led to poorer efficacy of HER2 receptor inhibitors. Moreover, autophagy, epithelial–mesenchymal transition, and tumor microenvironment can all contribute to the development of resistance in breast cancer cells. Based on the relevant research on the existing drug resistance mechanism, the current treatment plan for reversing the resistance of breast cancer to neoadjuvant chemotherapy is explored, and the potential drug targets are analyzed, aiming to provide a new idea and strategy to reverse the resistance of neoadjuvant chemotherapy drugs in breast cancer.

Synthesis and evaluation of a novel class of ethacrynic acid derivatives containing triazoles as potent anticancer agents

For unmet clinical needs, a novel class of ethacrynic acid (EA) derivatives containing triazole moieties (3a-i and 8) were designed, synthesized and evaluated as new anticancer agents. The in vitro anti-proliferative activities were assessed first on HL60 cell line and in a second stage, the two selected compounds 3a and 3c were tested on a panel of human cancer cell lines (A549, MCF7, PC3, U87-MG, SKOV3 and HCT116) and on a normal cell line (MCR5). Compound3c exhibited very good antitumor activities with IC₅₀ values of 20.2, 56.5 and 76.8 nM against A549, PC3 and U87-MG cell lines respectively, which is 2.8- and 1.3-fold more active than doxorubicin on A549 and U87-MG cancer cells, respectively. In addition, compound 3c displays a very good safety index (SI) of 82 fold for A549. Compound 3a showed also good IC₅₀ values of 50 nM on both A549 and PC3 cells and lower selectivity compared to 3c for A549 and PC3 vs. MCR5 with SI of 33 and 18 fold, respectively. The measurement of mitochondrial membrane potential on HCT116 cells after treatments by either 3a or 3c showed that both compounds induced mitochondrial dysfunctions causing thus caspase-induced apoptosis.

The Mechanisms of Yu Ping Feng San in Tracking the Cisplatin-Resistance by Regulating ATP-Binding Cassette Transporter and Glutathione S-Transferase in Lung Cancer Cells

Cisplatin is one of the first line anti-cancer drugs prescribed for treatment of solid tumors; however, the chemotherapeutic drug resistance is still a major obstacle of cisplatin in treating cancers. Yu Ping Feng San (YPFS), a well-known ancient Chinese herbal combination formula consisting of Astragali Radix, Atractylodis Macrocephalae Rhizoma and Saposhnikoviae Radix, is prescribed as a herbal decoction to treat immune disorders in clinic. To understand the fast-onset action of YPFS as an anti-cancer drug to fight against the drug resistance of cisplatin, we provided detailed analyses of intracellular cisplatin accumulation, cell viability, and expressions and activities of ATP-binding cassette transporters and glutathione S-transferases (GSTs) in YPFS-treated lung cancer cell lines. In cultured A549 or its cisplatin-resistance A549/DDP cells, application of YPFS increased accumulation of intracellular cisplatin, resulting in lower cell viability. In parallel, the activities and expressions of ATP-binding cassette transporters and GSTs were down-regulated in the presence of YPFS. The expression of p65 subunit of NF-κB complex was reduced by treating the cultures with YPFS, leading to a high ratio of Bax/Bcl-2, i.e. increasing the rate of cell death. Prim-O-glucosylcimifugin, one of the abundant ingredients in YPFS, modulated the activity of GSTs, and then elevated cisplatin accumulation, resulting in increased cell apoptosis. The present result supports the notion of YPFS in reversing drug resistance of cisplatin in lung cancer cells by elevating of intracellular cisplatin, and the underlying mechanism may be down regulating the activities and expressions of ATP-binding cassette transporters and GSTs.

Proteomics signature of autoimmune atrophic gastritis: towards a link with gastric cancer

BACKGROUND

Autoimmune atrophic gastritis (AAG) is a chronic disease that can progress to gastric cancer (GC). To better understand AAG pathology, this proteomics study investigated gastric proteins whose expression levels are altered in this disease and also in GC.

METHODS

Using two-dimensional difference gel electrophoresis (2D-DIGE), we compared protein maps of gastric corpus biopsies from AAG patients and controls. Differentially abundant spots (|fold change|≥ 1.5, P < 0.01) were selected and identified by LC-MS/MS. The spots were further assessed in gastric antrum biopsies from AAG patients (without and with Helicobacter pylori infection) and from GC patients and unaffected first-degree relatives of GC patients.

RESULTS

2D-DIGE identified 67 differentially abundant spots, with 28 more and 39 less abundant in AAG-corpus than controls. LC-MS/MS identified these as 53 distinct proteins. The most significant (adjusted P < 0.01) biological process associated with the less abundant proteins was "tricarboxylic acid cycle". Of the 67 spots, 57 were similarly differentially abundant in AAG-antrum biopsies irrespective of H. pylori infection status. The differential abundance was also observed in GC biopsies for 14 of 28 more abundant and 35 of 39 less abundant spots, and in normal gastric biopsies of relatives of GC patients for 6 and 25 spots, respectively. Immunoblotting confirmed the different expression levels of two more abundant proteins (PDIA3, GSTP gene products) and four less abundant proteins (ATP5F1A, PGA3, SDHB, PGC).

CONCLUSION

This study identified a proteomics signature of AAG. Many differential proteins were shared by GC and may be involved in the progression of AAG to GC.

Deciphering of The Effect of Chemotherapeutic Agents on Human Glutathione S-Transferase Enzyme and MCF-7 Cell Line

BACKGROUND

Cancer is the disease that causes the most death after cardiovascular diseases all over the world these days. Breast cancer is the most common type of cancer among women and ranks the second among cancer-related deaths after lung cancer. Chemotherapeutics act by killing cancer cells, preventing their spread and slowing their growth. Recent studies focus on the effects of chemotherapeutics on cancer cells and new chemotherapy approaches that targeting enzymes that catalyze important metabolic reactions in the cell.

OBJECTIVE

The aim of this study was to investigate the effects of chemotherapeutic agents, Tamoxifen and 5-FU, on MCF-7 cell line and human erythrocyte GST, an important enzyme of intracellular antioxidant metabolism.

METHODS

In this study, it was investigated that the effect of chemotherapeutic agents, Tamoxifen and 5-FU, on MCF-7 breast cancer cell line and performed ROS analyzes. In addition, it was purified glutathione S-transferase (GST), one of the important enzymes of intracellular antioxidant mechanism, from human erythrocytes by using ammonium sulfate precipitation and glutathione agarose affinity chromatography, and investigated in vitro effects of chemotherapeutic agents, 5 - FU and Tamoxifen, on the activity of this enzyme for the first time.

RESULTS

it was determined that Tamoxifen and 5-FU inhibited cellular viability and 5-FU increased intracellular levels of ROS, whereas Tamoxifen reduced intracellular levels of ROS. In addition, human erythrocyte GST enzyme with 16.2 EU/mg specific activity was purified 265.97-fold with a yield of 35% using ammonium sulfate precipitation and glutathione agarose affinity chromatography. The purity of the enzyme was checked by the SDS-PAGE method. In vitro effects of chemotherapeutics, 5-FU and Tamoxifen, on GST activity purified from human erythrocytes were investigated. The results showed that 5-FU increased the activity of GST in the concentration range of 77 to 1155 μM and that Tamoxifen increased the activity of GST in the concentration range of 0.54 to 2.70 μM.

CONCLUSION

In this study, the effects of tamoxifen and 5-FU chemotherapeutic agents on both MCF-7 cell line and human GST enzyme were examined together for the first time. Our study showed that chemotherapeutic agents (5-FU and Tamoxifen) inhibited cellular viability and Tamoxifen reduced intracellular levels of ROS whereas 5-FU increased intracellular levels of ROS. In addition, 5-FU and Tamoxifen were found to increase the activity of GST enzyme purified from the human erythrocyte.

Mitochondria-related core genes and TF-miRNA-hub mrDEGs network in breast cancer

Background: Mitochondria-nuclear cross-talk and mitochondrial retrograde regulation are involved in the genesis and development of breast cancer (BC). Therefore, mitochondria can be regarded as a promising target for BC therapeutic strategies. The present study aimed to construct regulatory network and seek the potential biomarkers of BC diagnosis and prognosis as well as the molecular therapeutic targets from the perspective of mitochondrial dysfunction. Methods: The microarray data of mitochondria-related encoding genes in BC cell lines were downloaded from GEO including GSE128610 and GSE72319. GSE128610 was treated as test set and validation sets consisted of GSE72319 and TCGA tissue samples, intending to identify mitochondria-related differentially expressed genes (mrDEGs). We performed enrichment analysis, PPI network, hub mrDEGs and overall survival analysis and constructed transcription factor (TF)-miRNA-hub mrDEGs network. Results: A total of 23 up-regulated and 71 down-regulated mrDEGs were identified and validated in BC cell lines and tissues. Enrichment analyses indicated that mrDEGs were associated with several cancer-related biological processes. Moreover, 9 hub mrDEGs were identified and validated in BC cell lines and tissues. Finally, 5 hub coregulated mrDEGs, 21 miRNAs and 117 TFs were used to construct TF-miRNA-hub mrDEGs network. MYC associated zinc finger protein (MAZ), heparin binding growth factor (HDGF) and Sp2 transcription factor (SP2) regulated 3 hub mrDEGs. Hsa-mir-21-5p, hsa-mir-1-3p, hsa-mir-218-5p, hsa-mir-26a-5p and hsa-mir-335-5p regulated 2 hub mrDEGs. Overall survival analysis suggested that the up-regulation of fibronectin 1 (FN1), as well as the down-regulation of discoidin domain receptor tyrosine kinase 2 (DDR2) correlated with unfavorable prognosis in BC. Conclusion: TF-miRNA-hub mrDEGs had instruction significance for the exploration of BC etiology. The hub mrDEGs such as FN1 and DDR2 were likely to regulate mitochondrial function and be novel biomarkers for BC diagnosis and prognosis as well as the therapeutic targets.

Metabolic pathways in sporadic colorectal carcinogenesis: A new proposal

Given the reports made about geographical differences in Colorectal Cancer (CRC) occurrence, suggesting a link between dietary habits, genes and cancer risk, we hypothesise that there are four fundamental metabolic pathways involved in diet-genes interactions, directly implicated in colorectal carcinogenesis: folate metabolism; lipid metabolism; oxidative stress response; and inflammatory response. Supporting this hypothesis are the evidence given by the significant associations between several diet-genes polymorphisms and CRC, namely: MTHFR, MTR, MTRR and TS (involved in folate metabolism); NPY, APOA1, APOB, APOC3, APOE, CETP, LPL and PON1 (involved in lipid metabolism); MNSOD, SOD3, CAT, GSTP1, GSTT1 and GSTM1 (involved in oxidative stress response); and IL-1, IL-6, TNF-α, and TGF-β (involved in inflammatory response). We also highlight the association between some foods/nutrients/nutraceuticals that are important in CRC prevention or treatment and the four metabolic pathways proposed, and the recent results of genome-wide association studies, both assisting our hypothesis. Finally, we propose a new line of investigation with larger studies, using accurate dietary biomarkers and investigating the four metabolic pathways genes simultaneously. This line of investigation will be essential to understand the full complexity of the association between nature and nurture in CRC and perhaps in other types of cancers. Only with this in-depth knowledge will it be possible to make personalised nutrition recommendations for disease prevention and management.

Dose and Sequence Dependent Synergism from the Combination of Oxaliplatin with Emetine and Patulin Against Colorectal Cancer

BACKGROUND

Colorectal cancer is the third most commonly diagnosed cancer in the world, causing many deaths every year. Combined chemotherapy has opened a new horizon in treating colorectal cancer. The objective of the present study is to investigate the activity of oxaliplatin in combination with emetine and patulin against colorectal cancer models.

METHODS

IC50 values of oxaliplatin, emetine and patulin were determined against human colorectal cancer cell lines (HT-29 and Caco-2) using MTT reduction assay. Synergistic, antagonistic and additive effects from the selected binary combinations were determined as a factor of sequence of administration and added concentrations. Proteomics was carried out to identify the proteins which were accountable for combined drug action applying to the selected drug combination.

RESULTS

Oxaliplatin in combination with patulin produced synergism against human colorectal cancer models depending on dose and sequence of drug administration. Bolus administration of oxaliplatin with patulin proved to be the best in terms of synergistic outcome. Altered expressions of nine proteins (ACTG, PROF1, PPIA, PDIA3, COF1, GSTP1, ALDOA, TBA1C and TBB5) were considered for combined drug actions of oxaliplatin with patulin.

CONCLUSION

Bolus administration of oxaliplatin with patulin has the potential to be used in the treatment of colorectal cancer, and would warrant further evaluation using suitable animal model.

In Vitro and in Vivo Efficacy of NBDHEX on Gefitinib-resistant Human Non-small Cell Lung Cancer

Gefitinib, a first-generation EGFR tyrosine kinase inhibitor (EGFR-TKI), is recommended for treatment of non-small cell lung cancer (NSCLC) patients who harbor activating EGFR mutations. However, the tumors of most patients initially sensitive to gefitinib will develop resistance within several months of therapy. Drug resistance is a major obstacle to NSCLC treatment. The novel glutathione transferase P1 (GSTPi) inhibitor 6-(7-nitro-2, 1, 3-benzoxadiazol-4-ylthio) hexanol (NBDHEX) has recently been shown to be active against tumors. In this study, we investigated the in vitro and in vivo efficacy of NBDHEX against NSCLC. Treatment with NBDHEX inhibited GSTpi enzymatic activity and promoted apoptosis of gefinitb-resistant NSCLC cells. Moreover, NBDHEX reduced tumor growth in mice. These findings indicated that NBDHEX is a good candidate for treatment of NSCLC patients, and that NBDHEX offers a new approach to cancer therapy.

Effects of GST null genotypes on individual susceptibility to atherosclerotic cardiovascular diseases: a meta-analysis

Some genetic association studies tried to investigate potential associations between glutathione S-transferase (GST) null genotypes and atherosclerotic cardiovascular diseases (ASCVD). However, the results of these studies were not consistent. Thus, we performed the present meta-analysis to explore associations between GST null genotypes and ASCVD in a larger pooled population. Systematic literature research was performed in PubMed, Web of Science, and Embase to identify eligible studies. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) to estimate the strength of associations. Totally 47 studies were included for analyses. Pooled analyses suggested that GSTM1 (p = .007, OR = 1.29, 95%CI 1.07-1.56) and GSTP1 (p = .01, OR = 1.28, 95%CI 1.06-1.55) null genotypes were significantly associated with individual susceptibility to ASCVD in overall population. Further subgroup analyses revealed similar positive results for GSTM1 null genotype in South Asians and patients with coronary artery disease (CAD). No other significant results were observed for GST null genotypes in overall and subgroup analyses. In conclusion, our meta-analysis suggested that GSTM1 and GSTP1 null genotypes could impact individual susceptibility to ASCVD. These results suggested that these variations could be used to identify individuals at higher susceptibility to ASCVD.

GST null polymorphisms may affect the risk of coronary artery disease: evidence from a meta-analysis

Background

Whether glutathione S-transferase (GST) null polymorphisms, namely GSTM1 null, GSTP1 null and GSTT1 null polymorphisms, influence the risk of coronary artery disease (CAD) or not remains unclear. Thus, the authors performed a meta-analysis to more robustly estimate associations between GST null polymorphisms and the risk of CAD by integrating the results of previous publications.

Methods

Medline, Embase, Wanfang, VIP and CNKI were searched comprehensively for eligible studies, and 45 genetic association studies were finally selected to be included in this meta-analysis.

Results

We found that GSTM1 null polymorphism was significantly associated with the risk of CAD in overall population (OR = 1.37, p = 0.003) and mixed population (OR = 1.61, p = 0.004), GSTP1 null polymorphism was significantly associated with the risk of CAD in overall population (OR = 1.23, p = 0.03), whereas GSTT1 null polymorphism was significantly associated with the risk of CAD in overall population (OR = 1.23, p = 0.02), Caucasians (OR = 1.23, p = 0.02) and East Asians (OR = 1.38, p < 0.0001).

Conclusions

This meta-analysis demonstrated that GSTM1 null, GSTP1 null and GSTT1 null polymorphisms were all significantly associated with an increased risk of CAD.

The glutathione S-transferase genes in marine rotifers and copepods: Identification of GSTs and applications for ecotoxicological studies

Various xenobiotics are constantly being released and accumulated into the aquatic environments and consequently, the aquatic organisms are continuously being exposed to exogenous stressors. Among various xenobiotic detoxifying enzymes, Glutathione S-transferase (GST) is one of the major xenobiotic detoxifying enzyme which is widely distributed among living organisms and thus, understanding of the nature of GSTs is crucial. Previous studies have shown GST activity in response to various xenobiotics yet, full identification of GSTs in marine invertebrates is still limited. This review covers information on the importance of GSTs as a biomarker for emerging chemicals and their response to wide ranges of environmental pollutants as well as in-depth phylogenetic analysis of marine invertebrates, including recently identified GSTs belonging to rotifers (Brachionus spp.) and copepods (Tigriopus japonicus and Paracyclopina nana), with unique class-specific features of GSTs, as well as a new suggestion of GST evolutionary pathway.

Glutathione S-transferase: a versatile protein family

Glutathione-S transferase (GST) is a most ancient protein superfamily of multipurpose roles and evolved principally from gene duplication of an ancestral GSH binding protein. They have implemented in diverse plant functions such as detoxification of xenobiotic, secondary metabolism, growth and development, and majorly against biotic and abiotic stresses. The vital structural features of GSTs like highly divergent functional topographies, conserved integrated architecture with separate binding pockets for substrates and ligand, the stringent structural fidelity with high Tm values (50º-60º), and stress-responsive cis-regulatory elements in the promoter region offer this protein as most flexible plant protein for plant breeding approaches, biotechnological applications, etc. This review article summarizes the recent information of GST evolution, and their distribution and structural features with emphasis on the assorted roles of Ser and Cys GSTs with the signature motifs in their active sites, alongside their recent biotechnological application in the area of agriculture, environment, and nanotechnology have been highlighted.

Targeting the Redox Landscape in Cancer Therapy

Reactive oxygen species (ROS) are produced predominantly by the mitochondrial electron transport chain and by NADPH oxidases in peroxisomes and in the endoplasmic reticulum. The antioxidative defense counters overproduction of ROS with detoxifying enzymes and molecular scavengers, for instance, superoxide dismutase and glutathione, in order to restore redox homeostasis. Mutations in the redox landscape can induce carcinogenesis, whereas increased ROS production can perpetuate cancer development. Moreover, cancer cells can increase production of antioxidants, leading to resistance against chemo- or radiotherapy. Research has been developing pharmaceuticals to target the redox landscape in cancer. For instance, inhibition of key players in the redox landscape aims to modulate ROS production in order to prevent tumor development or to sensitize cancer cells in radiotherapy. Besides the redox landscape of a single cell, alternative strategies take aim at the multi-cellular level. Extracellular vesicles, such as exosomes, are crucial for the development of the hypoxic tumor microenvironment, and hence are explored as target and as drug delivery systems in cancer therapy. This review summarizes the current pharmaceutical and experimental interventions of the cancer redox landscape.

Glutathione S-transferase M1 and T1 genes deletion polymorphisms and risk of developing essential hypertension: a case-control study in Burkina Faso population (West Africa)

BACKGROUND

Glutathione S-transferases play a key role in the detoxification of persistent oxidative stress products which are one of several risks factors that may be associated with many types of disease processes such as cancer, diabetes, and hypertension. In the present study, we characterize the null genotypes of GSTM1 and GSTT1 in order to investigate the association between them and the risk of developing essential hypertension.

METHODS

We conducted a case-control study in Burkina Faso, including 245 subjects with essential hypertension as case and 269 control subjects with normal blood pressure. Presence of the GSTT1 and GSTM1 was determined using conventional multiplex polymerase chain reaction followed by gel electrophoresis analysis. Biochemical parameters were measured using chemistry analyzer CYANExpert 130.

RESULTS

Chi-squared test shows that GSTT1-null (OR = 1.82; p = 0.001) and GSTM1-active/GSTT1-null genotypes (OR = 2.33; p <  0.001) were significantly higher in cases than controls; the differences were not significant for GSTM1-null, GSTM1-null/GSTT1-active and GSTM1-null/GSTT1-null (p > 0.05). Multinomial logistic regression revealed that age ≥ 50 years, central obesity, family history of hypertension, obesity, alcohol intake and GSTT1 deletion were in decreasing order independent risk factors for essential hypertension. Analysis by gender, BMI and alcohol showed that association of GSTT1-null with risk of essential hypertension seems to be significant when BMI < 30 Kg/m², in non-smokers and in alcohol users (all OR ≥ 1.77; p ≤ 0.008). Concerning GSTT1, GSTM1 and cardiovascular risk markers levels in hypertensive group, we found that subjects with GSTT1-null genotype had higher waist circumference and higher HDL cholesterol level than those with GSTT1-active (all p <  0.005), subjects with GSTM1-null genotype had lower triglyceride than those with GSTM1-active (p = 0.02) and subjects with the double deletion GSTM1-null/GSTT1-null had higher body mass index, higher waist circumference and higher HDL cholesterol than those with GSTM1-active/GSTT1-active genotype (all p = 0.01).

CONCLUSION

Our results confirm that GSTT1-null genotype is significantly associated with risk of developing essential hypertension in Burkinabe, especially when BMI < 30 Kg/m², in non-smokers and in alcohol users, and it showed that the double deletion GSTM1-null/GSTT1-null genotypes may influence body lipids repartition.

GSTP1 rs1138272 Polymorphism Affects Prostate Cancer Risk

Background and Objectives: One of the most frequent genetic alterations reported to date in prostate cancer (PC) is aberrant methylation of glutathione transferase P1 (GSTP1). Taking into consideration the involvement of oxidative stress in PC pathogenesis and recent advances in scientific understanding of the role of GSTP1*Ala114Val rs1138272 polymorphism in carcinogenesis, we hypothesized that this single-nucleotide polymorphism (SNP) influences the risk of PC independently of, or in combination with, other GST polymorphisms, including GSTP1*IIe105Val rs1695 or GSTM1 and GSTT1 deletion polymorphisms. Materials and Methods: Genotyping was performed in 237 PC cases and in 236 age-matched controls by multiplex polymerase chain reaction (PCR) for deletion of GST polymorphisms and by quantitative PCR for SNPs. Results: We found that carriers of either GSTP1*Val (rs1138272) or GSTP1*Val (rs1695) variant alleles had a PC risk compared to individuals with both referent alleles (OR = 4.93, 95%CI: 2.89–8.40, p < 0.001 and OR = 1.8, 95%CI: 1.19–2.73, p = 0.006, respectively). Additionally, in a haplotype analysis we found that individuals with GSTP1*C haplotype, represented by both variant alleles (GSTP1*Val rs1695 + GSTP1*Val rs1138272), had a 5.46 times higher risk of PC development compared to individuals with the most frequent haplotype (95%CI = 2.56–11.65, p < 0.001), suggesting a potential role of those variants in PC susceptibility. A regression analysis on the number of risk-associated alleles per individual (GSTM1*active, GSTT1*null, GSTP1*Val rs1695 and GSTP1*Val rs1138272) showed a significant increase in the risk of developing PC, from 3.65-fold in carriers of two risk alleles (95%CI = 1.55–8.61, p = 0.003) to an approximately 12-fold increase in carriers of all four risk alleles (95%CI = 3.05–44.93, p < 0.001). Conclusion: Prostate cancer may be influenced by multiple glutathione transferase (GST) polymorphic genes, especially GSTP1, highlighting the role of gene–gene interactions in human susceptibility to this cancer.

Glutathione transferase genotypes may serve as determinants of risk and prognosis in renal cell carcinoma

Renal cell carcinoma (RCC) represents a group of histologically similar neoplasms with significant intratumor and intertumor genetic heterogeneity. Recognized risk factors for RCC development include smoking, hypertension, obesity, as well as von Hippel-Lindau (VHL) disease. Inactivation of VHL, deregulated nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway, and altered redox homeostasis, together with changes in glutathione transferase (GST) profile, are considered as important contributing factors in RCC development and progression. Although the available results of both gene-gene and gene-environment analysis are quite heterogeneous, they clearly indicate that certain GST genotypes may play a role as risk modifiers, either individually or in combination with other Phase I or Phase II gene polymorphisms, as well as in subjects exposed to relevant substrates. Seemingly, GST genotyping could identify individuals with impaired detoxification in renal parenchyma that are at higher risk of developing RCC. In addition to well established roles of GSTs in conjugation and biotransformation of xenobiotics, GSTs have emerged as significant regulators of pathways determining cell proliferation and survival. Indeed, there are evidence in favor of GST significance, not only in terms of risk for RCC development, but also with respect to progression and prognosis. So far, GSTM1-active genotype was confirmed to be an independent predictor of higher risk of overall mortality. Therefore, it is reasonable to assume that certain GST variants may assist in individual RCC risk assessment, as well as postoperative prognosis. Even more, GST profiling might contribute to development of personalized targeted therapy in RCC patients.

GSTP1 and cancer: Expression, methylation, polymorphisms and signaling (Review)

Glutathione S‑transferase Pi (GSTP1) is an isozyme encoded by the GST pi gene that plays an important regulatory role in detoxification, anti‑oxidative damage, and the occurrence of various diseases. The aim of the present study was to review the association between the expression of GSTP1 and the development and treatment of various cancers, and discuss GSTP1 methylation in several malignant tumors, such as prostate, breast and lung cancer, as well as hepatocellular carcinoma; to review the association between polymorphism of the GSTP1 gene and various diseases; and to review the effects of GSTP1 on electrophilic oxidative stress, cell signal transduction, and the regulation of carcinogenic factors. Collectively, GSTP1 plays a major role in the development of various diseases.

Predictive Value of Pin1 in Cervical Low-Grade Squamous Intraepithelial Lesions and Inhibition of Pin1 Exerts Potent Anticancer Activity against Human Cervical Cancer

Many oncogenes are involved in the progression from low-grade squamous intraepithelial lesions (LSILs) to high-grade squamous intraepithelial lesions (HSILs); which greatly increases the risk of cervical cancer (CC). Thus, a reliable biomarker for risk classification of LSILs is urgently needed. The prolyl isomerase Pin1 is overexpressed in many cancers and contributes significantly to tumour initiation and progression. Therefore, it is important to assess the effects of cancer therapies that target Pin1. In our study, we demonstrated that Pin1 may serve as a biomarker for LSIL disease progression and may constitute a novel therapeutic target for CC. We used a the novel Pin1 inhibitor KPT-6566, which is able to covalently bind to Pin1 and selectively target it for degradation. The results of our investigation revealed that the downregulation of Pin1 by shRNA or KPT-6566 inhibited the growth of human cervical cancer cells (CCCs). We also discovered that the use of KPT-6566 is a novel approach to enhance the therapeutic efficacy of cisplatin (DDP) against CCCs in vitro and in vivo. We showed that KPT-6566-mediated inhibition of Pin1 blocked multiple cancer-driving pathways simultaneously in CCCs. Furthermore, targeted Pin1 treatment suppressed the metastasis and invasion of human CCCs, and downregulation of Pin1 reversed the epithelial-mesenchymal transition (EMT) of CCCs via the c-Jun/slug pathway. Collectively, we showed that Pin1 may be a marker for the risk of progression to HSIL and that inhibition of Pin1 has anticancer effects against CC.

The mercapturic acid pathway

The mercapturic acid pathway is a major route for the biotransformation of xenobiotic and endobiotic electrophilic compounds and their metabolites. Mercapturic acids (N-acetyl-l-cysteine S-conjugates) are formed by the sequential action of the glutathione transferases, γ-glutamyltransferases, dipeptidases, and cysteine S-conjugate N-acetyltransferase to yield glutathione S-conjugates, l-cysteinylglycine S-conjugates, l-cysteine S-conjugates, and mercapturic acids; these metabolites constitute a "mercapturomic" profile. Aminoacylases catalyze the hydrolysis of mercapturic acids to form cysteine S-conjugates. Several renal transport systems facilitate the urinary elimination of mercapturic acids; urinary mercapturic acids may serve as biomarkers for exposure to chemicals. Although mercapturic acid formation and elimination is a detoxication reaction, l-cysteine S-conjugates may undergo bioactivation by cysteine S-conjugate β-lyase. Moreover, some l-cysteine S-conjugates, particularly l-cysteinyl-leukotrienes, exert significant pathophysiological effects. Finally, some enzymes of the mercapturic acid pathway are described as the so-called "moonlighting proteins," catalytic proteins that exert multiple biochemical or biophysical functions apart from catalysis.

Dual roles of glutathione S-transferase mu 1 in the development and metastasis of hepatocellular carcinoma

PURPOSE

Reactive oxygen species (ROS) are implicated in carcinogenesis, and cellular antioxidant systems are important for detoxifying ROS and reversing oxidant-mediated modifications. Glutathione S-transferase mu (GSTM) belongs to a family of phase II detoxification enzymes that catalyze the conjugation of reduced glutathione (GSH) to a wide range of endogenous and exogenous electrophilic compounds. The genotype of GSTM1 was associated with the risk and prognosis of cancer in several meta-analyses. This study explored the function of GSTM1 in hepatocellular carcinoma (HCC).

METHODS

Polymerase chain reaction (PCR) and western blotting (WB) were used to detect the levels of gene and protein expression. MTS assays, Transwell assays, and flow cytometry were used to explore the function of GSTM1 in vitro. The xenograft assay and tail vein injection model were used to explore the function of GSTM1 in vivo.

RESULTS

The mRNA and protein expression of GSTM1 was downregulated in HCC, but the expression levels of GSTM1 were not correlated with patient survival time. In vitro, Transwell and doxorubicin (DOX)-induced apoptosis assays revealed that GSTM1 showed opposite functions in different HCC cell lines with varied TP53 genotype statuses. The overexpression of GSTM1 in the above cell lines led to a significant decrease in ROS and an increase in GSH concentration and TP53 levels, suggesting that the controversial role of GSTM1 resulted from the TP53 genotype of HCC cells. The overexpression of GSTM1 promoted cell migration and inhibited apoptosis in the MHCC-97H cell line (TP53, R249S), but inhibited cell migration and increased apoptosis in the SMMC-7721 cell line (TP53 wildtype).

CONCLUSION

GSTM1 down-regulation may partially account for ROS-mediated oxidative damage and HCC carcinogenesis. GSTM1 also regulates tumor progression by disrupting the ROS-TP53 axis in HCC cells with different genetic backgrounds.

A three-gene DNA methylation biomarker accurately classifies early stage prostate cancer

BACKGROUND

We identify and validate accurate diagnostic biomarkers for prostate cancer through a systematic evaluation of DNA methylation alterations.

MATERIALS AND METHODS

We assembled three early prostate cancer cohorts (total patients = 699) from which we collected and processed over 1300 prostatectomy tissue samples for DNA extraction. Using real-time methylation-specific PCR, we measured normalized methylation levels at 15 frequently methylated loci. After partitioning sample sets into independent training and validation cohorts, classifiers were developed using logistic regression, analyzed, and validated.

RESULTS

In the training dataset, DNA methylation levels at 7 of 15 genomic loci (glutathione S-transferase Pi 1 [GSTP1], CCDC181, hyaluronan, and proteoglycan link protein 3 [HAPLN3], GSTM2, growth arrest-specific 6 [GAS6], RASSF1, and APC) showed large differences between cancer and benign samples. The best binary classifier was the GAS6/GSTP1/HAPLN3 logistic regression model, with an area under these curves of 0.97, which showed a sensitivity of 94%, and a specificity of 93% after external validation.

CONCLUSION

We created and validated a multigene model for the classification of benign and malignant prostate tissue. With false positive and negative rates below 7%, this three-gene biomarker represents a promising basis for more accurate prostate cancer diagnosis.

Identification of Catechol-Type Diphenylbutadiene as a Tyrosinase-Activated Pro-oxidative Chemosensitizer against Melanoma A375 Cells via Glutathione S-Transferase Inhibition

Glutathione S-transferases (GSTs) play an active role in the development of drug resistance by numerous cancer cells, including melanoma cells, which is a major cause of chemotherapy failure. As part of our continuous effort to explore why dietary polyphenols bearing the catechol moiety (dietary catechols) show usually anticancer activity, catechol-type diphenylbutadiene (3,4-DHB) was selected as a model of dietary catechols to probe whether they work as pro-oxidative chemosensitizers via GST inhibition in melanoma cells. It was found that, in human melanoma A375 cells, 3,4-DHB is easily converted to its ortho-quinone via copper-containing tyrosinase-mediated two-electron oxidation along with generation of reactive oxygen species (ROS) derived from the oxidation; the resulting ortho-quinone and ROS are responsible for its ability to sensitize the cisplatin-resistant cells by inhibiting GST, followed by induction of apoptosis in an ASK1-JNK/p38 signaling cascade and mitochondria-dependent pathway. This work provides further evidence to support that dietary catechols exhibit antimelanoma activity by virtue of their tyrosinase-dependent pro-oxidative role and gives useful information for designing polyphenol-inspired GST inhibitors and sensitizers in chemotherapy against melanoma.