Importance of glucose-6-phosphate dehydrogenase activity in cell death

Metabolomics and cellular altered pathways in cancer biology: A review

Cancer is a deadly disease that affects a cell's metabolism and surrounding tissues. Understanding the fundamental mechanisms of metabolic alterations in cancer cells would assist in developing cancer treatment targets and approaches. From this perspective, metabolomics is a great analytical tool to clarify the mechanisms of cancer therapy as well as a useful tool to investigate cancer from a distinct viewpoint. It is a powerful emerging technology that detects up to thousands of molecules in tissues and biofluids. Like other "-omics" technologies, metabolomics involves the comprehensive investigation of micromolecule metabolites and can reveal important details about the cancer state that is otherwise not apparent. Recent developments in metabolomics technologies have made it possible to investigate cancer metabolism in greater depth and comprehend how cancer cells utilize metabolic pathways to make the amino acids, nucleotides, and lipids required for tumorigenesis. These new technologies have made it possible to learn more about cancer metabolism. Here, we review the cellular and systemic effects of cancer and cancer treatments on metabolism. The current study provides an overview of metabolomics, emphasizing the current technologies and their use in clinical and translational research settings.

Phoenixin-14 may ameliorate testicular damage caused by torsion-detorsion by reducing oxidative stress and inflammation in prepubertal rats

The present study aimed to investigate the effects of Phoenixin-14 (PNX-14) on oxidative damage, inflammatory response, histopathological variations, and serum testosterone levels in testicular tissues. Forty-eight Wistar albino prepubertal male rats were divided into 4 groups (Sham, TTD, TT+PNX+TD, TTD+PNX) (n=12). The torsion period was 2 hours and the detorsion period was 24 hours in the testicular torsion/detorsion (TD) groups. A single PNX-14 (50 µg/kg) dose was injected into the rats in the TT+PNX TD group on the 90th minute of torsion, and it was injected into the rats in the TTD+PNX group at the beginning of detorsion. Oxidative damage in testicular tissues was determined based on superoxide dismutase (SOD), malondialdehyde (MDA), total antioxidant status (TAS) and total oxidant status (TOS), and inflammatory damage was determined based on TNF-α and IL-6 levels. Histopathological variations were investigated with the Periodic Acid Schiff (PAS) staining method in testicular tissues and analyzed based on Johnsen scores. Spermatogonia cells were examined immunohistochemically. Serum testosterone levels were determined with the enzyme-linked immunosorbent assay (ELISA). A significant increase in oxidative stress and inflammation parameters was determined in the TTD group when compared to the other groups (p<0.05). PNX-14 treatment led to a statistically significant decrease in these parameters and significantly repaired the TD damage in testicular tissue (p<0.05). Johnsen scoring revealed significant improvement in PNX-14 groups and an increase in spermatogonia count, supporting the biochemical findings (p<0.05). PNX-14 could be a potential therapeutic agent in testicular TD damage and further studies should be conducted to elucidate the present study findings.

In vivo CRISPR screening directly targeting testicular cells

CRISPR-Cas9 short guide RNA (sgRNA) library screening is a powerful approach to understand the molecular mechanisms of biological phenomena. However, its in vivo application is currently limited. Here, we developed our previously established in vitro revival screening method into an in vivo one to identify factors involved in spermatogenesis integrity by utilizing sperm capacitation as an indicator. By introducing an sgRNA library into testicular cells, we successfully pinpointed the retinal degeneration 3 (Rd3) gene as a significant factor in spermatogenesis. Single-cell RNA sequencing (scRNA-seq) analysis highlighted the high expression of Rd3 in round spermatids, and proteomics analysis indicated that Rd3 interacts with mitochondria. To search for cell-type-specific signaling pathways based on scRNA-seq and proteomics analyses, we developed a computational tool, Hub-Explorer. Through this, we discovered that Rd3 modulates oxidative stress by regulating mitochondrial distribution upon ciliogenesis induction. Collectively, our screening system provides a valuable in vivo approach to decipher molecular mechanisms in biological processes.

Glucose-6-phosphate dehydrogenase deficiency accelerates arterial aging in diabetes

AIMS

High glucose levels and Glucose-6-Phosphate Dehydrogenase deficiency (G6PDd) have both tissue inflammatory effects. Here we determined whether G6PDd accelerates arterial aging (information linked stiffening) in diabetes.

METHODS

Plasma glucose, interleukin 6 (IL6), and arterial stiffness (indexed as carotid-femoral Pulse Wave Velocity, PWV) and red blood cell G6PD activity were assessed in a large (4448) Sardinian population.

RESULTS

Although high plasma glucose in diabetics, did not differ by G6DP status (178.2 ± 55.1 vs 169.0 ± 50.1 mg/dl) in G6DPd versus non-G6PDd subjects, respectively, IL6, and PWV (adjusted for age and glucose) were significantly increased in G6PDd vs non-G6PDd subjects (PWV, 8.0 ± 0.4 vs 7.2 ± 0.2 m/sec) and (IL6, 6.9 ± 5.0 vs 4.2 ± 3.0 pg/ml). In non-diabetics, neither fasting plasma glucose, nor IL6, nor PWV were impacted by G6PDd.

CONCLUSION

G6PDd in diabetics is associated with increased inflammatory markers and accelerated arterial aging.

G6PDH as a key immunometabolic and redox trigger in arthropods

The enzyme glucose-6-phosphate dehydrogenase (G6PDH) plays crucial roles in glucose homeostasis and the pentose phosphate pathway (PPP), being also involved in redox metabolism. The PPP is an important metabolic pathway that produces ribose and nicotinamide adenine dinucleotide phosphate (NADPH), which are essential for several physiologic and biochemical processes, such as the synthesis of fatty acids and nucleic acids. As a rate-limiting step in PPP, G6PDH is a highly conserved enzyme and its deficiency can lead to severe consequences for the organism, in particular for cell growth. Insufficient G6PDH activity can lead to cell growth arrest, impaired embryonic development, as well as a reduction in insulin sensitivity, inflammation, diabetes, and hypertension. While research on G6PDH and PPP has historically focused on mammalian models, particularly human disorders, recent studies have shed light on the regulation of this enzyme in arthropods, where new functions were discovered. This review will discuss the role of arthropod G6PDH in regulating redox homeostasis and immunometabolism and explore potential avenues for further research on this enzyme in various metabolic adaptations.

Evaluation and validation of reference genes for RT-qPCR gene expression in Naegleria gruberi

Naegleria gruberi is a free-living amoeboflagellate commonly found in freshwater and in soils around the world. It is a non-pathogenic relative of Naegleria fowleri, which is the etiologic agent of Primary Amoebic Meningoencephalitis (PAM). PAM occurs world-wide and it is considered a rare disease, but its fatality rate is high (96%) mainly because of delay in initiation of treatment due to misdiagnosis and lack of a specific treatment. The analysis of gene expression by quantitative real-time PCR in N. gruberi could be a highly efficient means to understand the pathogenicity of N. fowleri and also to find drug targets. Accurate RT-qPCR analysis requires correct normalization of gene expression data using reference genes (RG), whose expression should be constant under different experimental conditions. In this study, six genes, representing the most frequently used housekeeping genes, were selected for evaluation as reference genes in N. gruberi. The expression and stability of these genes was evaluated employing four algorithms (geNorm, NormFinder, BestKeeper and RefFinder). This work shows significant variations of the stability of RGs depending on the algorithms employed and on the experimental conditions (i.e. logarithmic, stationary, heat-shock and oxidative stress). The geNorm, NormFinder and RefFinder analysis of all the experimental conditions in combination revealed that ACT and G6PD were the most stable RGs. While BestKeeper analysis showed that 18S and TBP were the most stable RGs. Moreover, normalization of HSP90 gene expression with the most stable RGs resulted in an upregulation whereas when the normalization was done with the unstable RGs, the gene expression was not reliable. Hence, the implications of this study are relevant to gene expression studies in N. gruberi.

Anti-Aging Effects of Quercetin in Cladocera Simocephalus vetulus Using Proteomics

Quercetin is a flavonoid widely found in food and traditional herbs. In this study, we evaluated the anti-aging effects of quercetin on Simocephalus vetulus (S. vetulus) by assessing lifespan and growth parameters and analyzed the differentially expressed proteins and crucial pathways associated with quercetin activity using proteomics. The results demonstrated that, at a concentration of 1 mg/L, quercetin significantly prolonged the average and maximal lifespans of S. vetulus and increased the net reproduction rate slightly. The proteomics-based analysis revealed 156 differently expressed proteins, with 84 being significantly upregulated and 72 significantly downregulated. The protein functions were identified as being associated with glycometabolism, energy metabolism, and sphingolipid metabolism pathways, and the key enzyme activity and related gene expression, such that of AMPK, supported the importance of these pathways in the anti-aging activity of quercetin. In addition, quercetin was found to regulate the anti-aging-related proteins Lamin A and Klotho directly. Our results increased the understanding of quercetin's anti-aging effects.

AMP-activated protein kinase: An energy sensor and survival mechanism in the reinstatement of metabolic homeostasis

Cells are programmed to favorably respond towards the nutrient availability by adapting their metabolism to meet energy demands. AMP-activated protein kinase (AMPK) is a highly conserved serine/threonine energy-sensing kinase. It gets activated upon a decrease in the cellular energy status as reflected by an increased AMP/ATP ratio, ADP, and also during the conditions of glucose starvation without change in the adenine nucelotide ratio. AMPK functions as a centralized regulator of metabolism, acting at cellular and physiological levels to circumvent the metabolic stress by restoring energy balance. This review intricately highlights the integrated signaling pathways by which AMPK gets activated allosterically or by multiple non-canonical upstream kinases. AMPK activates the ATP generating processes (e.g., fatty acid oxidation) and inhibits the ATP consuming processes that are non-critical for survival (e.g., cell proliferation, protein and triglyceride synthesis). An integrated signaling network with AMPK as the central effector regulates all the aspects of enhanced stress resistance, qualified cellular housekeeping, and energy metabolic homeostasis. Importantly, the AMPK mediated amelioration of cellular stress and inflammatory responses are mediated by stimulation of transcription factors such as Nrf2, SIRT1, FoxO and inhibition of NF-κB serving as main downstream effectors. Moreover, many lines of evidence have demonstrated that AMPK controls autophagy through mTOR and ULK1 signaling to fine-tune the metabolic pathways in response to different cellular signals. This review also highlights the critical involvement of AMPK in promoting mitochondrial health, and homeostasis, including mitophagy. Loss of AMPK or ULK1 activity leads to aberrant accumulation of autophagy-related proteins and defective mitophagy thus, connecting cellular energy sensing to autophagy and mitophagy.

Dual inhibition of CPT1A and G6PD suppresses glioblastoma tumorspheres

PURPOSE

Limited treatment options are currently available for glioblastoma (GBM), an extremely lethal type of brain cancer. For a variety of tumor types, bioenergetic deprivation through inhibition of cancer-specific metabolic pathways has proven to be an effective therapeutic strategy. Here, we evaluated the therapeutic effects and underlying mechanisms of dual inhibition of carnitine palmitoyltransferase 1A (CPT1A) and glucose-6-phosphate dehydrogenase (G6PD) critical for fatty acid oxidation (FAO) and the pentose phosphate pathway (PPP), respectively, against GBM tumorspheres (TSs).

METHODS

Therapeutic efficacy against GBM TSs was determined by assessing cell viability, neurosphere formation, and 3D invasion. Liquid chromatography-mass spectrometry (LC-MS) and RNA sequencing were employed for metabolite and gene expression profiling, respectively. Anticancer efficacy in vivo was examined using an orthotopic xenograft model.

RESULTS

CPT1A and G6PD were highly expressed in GBM tumor tissues. Notably, siRNA-mediated knockdown of both genes led to reduced viability, ATP levels, and expression of genes associated with stemness and invasiveness. Similar results were obtained upon combined treatment with etomoxir and dehydroepiandrosterone (DHEA). Transcriptome analyses further confirmed these results. Data from LC-MS analysis showed that this treatment regimen induced a considerable reduction in the levels of metabolites associated with the TCA cycle and PPP. Additionally, the combination of etomoxir and DHEA inhibited tumor growth and extended survival in orthotopic xenograft model mice.

CONCLUSION

Our collective findings support the utility of dual suppression of CPT1A and G6PD with selective inhibitors, etomoxir and DHEA, as an efficacious therapeutic approach for GBM.

Enhancing intracellular NADPH bioavailability through improving pentose phosphate pathway flux and its application in biocatalysis asymmetric reduction reaction

The intracellular NAD(P)H insufficiency is the key factor which limits the reduced product (such as chiral alcohols) synthesis by whole cell biocatalysis or microbial cell factory. In this paper, we reported a novel solution to increase NADPH supply through strengthening the pentose phosphate pathway (PPP) flux with overexpression of extra zwf (gene for glucose 6-phosphatedehydrogenase) and glk (gene for glucokinase) by recombinant Escherichia coli BL21(DE3)/pETDuet-1-glk-zwf and pET28a-bccr containing a carbonyl reductase gene bccr. The amount of intracellular NADPH was significantly increased from 150.3 μmol/L to 681.8 μmol/L after strengthening the PPP flux, which was 4.5-fold to that of the control. It was applied to improve the asymmetric reduction of 4-chloroacetoacetate to ethyl S-4-chloro-3-hydroxybutylate catalyzed by the BcCR, which increased the reaction yield 2.8-fold to the control. This strategy provides a new way to increase NADPH supply in E. coli cell factories.

Glucose 6-P Dehydrogenase—An Antioxidant Enzyme with Regulatory Functions in Skeletal Muscle during Exercise

Hypomorphic Glucose 6-P dehydrogenase (G6PD) alleles, which cause G6PD deficiency, affect around one in twenty people worldwide. The high incidence of G6PD deficiency may reflect an evolutionary adaptation to the widespread prevalence of malaria, as G6PD-deficient red blood cells (RBCs) are hostile to the malaria parasites that infect humans. Although medical interest in this enzyme deficiency has been mainly focused on RBCs, more recent evidence suggests that there are broader implications for G6PD deficiency in health, including in skeletal muscle diseases. G6PD catalyzes the rate-limiting step in the pentose phosphate pathway (PPP), which provides the precursors of nucleotide synthesis for DNA replication as well as reduced nicotinamide adenine dinucleotide phosphate (NADPH). NADPH is involved in the detoxification of cellular reactive oxygen species (ROS) and de novo lipid synthesis. An association between increased PPP activity and the stimulation of cell growth has been reported in different tissues including the skeletal muscle, liver, and kidney. PPP activity is increased in skeletal muscle during embryogenesis, denervation, ischemia, mechanical overload, the injection of myonecrotic agents, and physical exercise. In fact, the highest relative increase in the activity of skeletal muscle enzymes after one bout of exhaustive exercise is that of G6PD, suggesting that the activation of the PPP occurs in skeletal muscle to provide substrates for muscle repair. The age-associated loss in muscle mass and strength leads to a decrease in G6PD activity and protein content in skeletal muscle. G6PD overexpression in Drosophila Melanogaster and mice protects against metabolic stress, oxidative damage, and age-associated functional decline, and results in an extended median lifespan. This review discusses whether the well-known positive effects of exercise training in skeletal muscle are mediated through an increase in G6PD.

Reduced nicotinamide adenine dinucleotide phosphate in redox balance and diseases: a friend or foe?

The nicotinamide adenine dinucleotide (NAD⁺/NADH) and nicotinamide adenine dinucleotide phosphate (NADP⁺/NADPH) redox couples function as cofactors or/and substrates for numerous enzymes to retain cellular redox balance and energy metabolism. Thus, maintaining cellular NADH and NADPH balance is critical for sustaining cellular homeostasis. The sources of NADPH generation might determine its biological effects. Newly-recognized biosynthetic enzymes and genetically encoded biosensors help us better understand how cells maintain biosynthesis and distribution of compartmentalized NAD(H) and NADP(H) pools. It is essential but challenging to distinguish how cells sustain redox couple pools to perform their integral functions and escape redox stress. However, it is still obscure whether NADPH is detrimental or beneficial as either deficiency or excess in cellular NADPH levels disturbs cellular redox state and metabolic homeostasis leading to redox stress, energy stress, and eventually, to the disease state. Additional study of the pathways and regulatory mechanisms of NADPH generation in different compartments, and the means by which NADPH plays a role in various diseases, will provide innovative insights into its roles in human health and may find a value of NADPH for the treatment of certain diseases including aging, Alzheimer's disease, Parkinson's disease, cardiovascular diseases, ischemic stroke, diabetes, obesity, cancer, etc.

Metabolic Analysis of Schizochytrium Mutants With High DHA Content Achieved With ARTP Mutagenesis Combined With Iodoacetic Acid and Dehydroepiandrosterone Screening

High DHA production cost caused by low DHA titer and productivity of the current Schizochytrium strains is a bottleneck for its application in competition with traditional fish-oil based approach. In this study, atmospheric and room-temperature plasma with iodoacetic acid and dehydroepiandrosterone screening led to three mutants, 6–8, 6–16 and 6–23 all with increased growth and DHA accumulations. A LC/MS metabolomic analysis revealed the increased metabolism in PPP and EMP as well as the decreased TCA cycle might be relevant to the increased growth and DHA biosynthesis in the mutants. Finally, the mutant 6–23, which achieved the highest growth and DHA accumulation among all mutants, was evaluated in a 5 L fermentor. The results showed that the DHA concentration and productivity in mutant 6–23 were 41.4 g/L and 430.7 mg/L/h in fermentation for 96 h, respectively, which is the highest reported so far in literature. The study provides a novel strain improvement strategy for DHA-producing Schizochytrium.

Efficiency of Combined Use of Fullerene C60 and Bovine Serum Albumin for Rehabilitation of Vitrified Fragments of Rat Immature Seminiferous Tubules

Background. Today, cryopreserved reproductive tissues are used to treat some forms of male infertility. However, after long-term preservation of fragments of seminiferous tubules of testes (FSTT) in a low-temperature bank (-196 °С) their morphological and functional characteristics decrease reversibly. To solve this problem after freezing-thawing, the use of rehabilitation media with special additives is promising. Due to the fact that serum albumin and fullerene C60 have powerful protective and antioxidant properties, their use allows to stabilize the plasma membrane, osmotic pressure, and reduce free radicals that make them promising candidates to use in the development of rehabilitation media for biological objects after cryopreservation. Objective. The efficacy of fullerene C60, bovine serum albumin (BSA), and their combination as components of rehabilitation medium of vitrified FSTT of immature rats was studied. Methods. Vitrified-thawed samples of FSTT were incubated (22 °C) for 30 minutes in Leibovitz's medium with addition of 15 mg/mL C60, 5 g/L BSA or their combination. Control samples were incubated in the medium without C60 or BSA addition. Metabolic activity (MTT test), histomorphological data, total antioxidant status (TAS), reactive oxygen species (ROS) production, activity of g-glutamyltransferase (gGGT), and glucose-6-phosphate dehydrogenase were determined in the samples after rehabilitation in the investigated media. Results. The use of C60 led to the increase of metabolic (by 1.26 times) and TAS (by 1.74 times) activities, to the decrease in the number of ROS+ cells (by 1.35 times) and to the improvement of the spermatogenic epithelium binding to the basement membrane versus control sample. Application of BSA did not significantly affect the studied biochemical indices but decreased the number of tubules with desquamation of spermatogenic epithelium in histological sections. The combined use of BSA and C60 had the best effect among investigated rehabilitation media that led to the increase of metabolic activity (by 1.51 times), TAS activity (by 1.78 times), gGGT activity (by 1.59 times), histostructure restoration and the decrease in the number of ROS+ cells (by 1.45 times) compared to the control samples. Conclusions. The use of C60 and BSA combination increases the metabolic and antioxidant activity of vitrified FSTT and also has a positive effect on their histostructural characteristics compared to control samples. It should be noted that the effect of С60 and BSA addition to rehabilitation medium exceeds the results of using the investigated additives separately (by the metabolic and gGGT activity as well as architectonics of vitrified FSTT). These data relate to reproductive medicine and can be used to develop an effective rehabilitation protocol for vitrified FSTT.

Boron Oxide Nanoparticles Exhibit Minor, Species-Specific Acute Toxicity to North-Temperate and Amazonian Freshwater Fishes

Boron oxide nanoparticles (nB₂O₃) are manufactured for structural, propellant, and clinical applications and also form spontaneously through the degradation of bulk boron compounds. Bulk boron is not toxic to vertebrates but the distinctive properties of its nanostructured equivalent may alter its biocompatibility. Few studies have addressed this possibility, thus our goal was to gain an initial understanding of the potential acute toxicity of nB₂O₃ to freshwater fish and we used a variety of model systems to achieve this. Bioactivity was investigated in rainbow trout (Oncorhynchus mykiss) hepatocytes and at the whole animal level in three other North and South American fish species using indicators of aerobic metabolism, behavior, oxidative stress, neurotoxicity, and ionoregulation. nB₂O₃ reduced O. mykiss hepatocyte oxygen consumption (ṀO₂) by 35% at high doses but whole animal ṀO₂ was not affected in any species. Spontaneous activity was assessed using ṀO₂ frequency distribution plots from live fish. nB₂O₃ increased the frequency of high ṀO₂ events in the Amazonian fish Paracheirodon axelrodi, suggesting exposure enhanced spontaneous aerobic activity. ṀO₂ frequency distributions were not affected in the other species examined. Liver lactate accumulation and significant changes in cardiac acetylcholinesterase and gill Na⁺/K⁺-ATPase activity were noted in the north-temperate Fundulus diaphanus exposed to nB₂O₃, but not in the Amazonian Apistogramma agassizii or P. axelrodi. nB₂O₃ did not induce oxidative stress in any of the species studied. Overall, nB₂O₃ exhibited modest, species-specific bioactivity but only at doses exceeding predicted environmental relevance. Chronic, low dose exposure studies are required for confirmation, but our data suggest that, like bulk boron, nB₂O₃ is relatively non-toxic to aquatic vertebrates and thus represents a promising formulation for further development.

Possible inhibition mechanism of dobutamine hydrochloride as potent inhibitor for human glucose-6-phosphate dehydrogenase enzyme

Glucose-6-phosphate dehydrogenase (G6PD) is the first rate-limiting enzyme in the pentose phosphate pathway. One of the enzyme's most important functions is the production of a reducing agent that is essential for preserving the level of reduced glutathione (GSH). However, some chemicals, such as industrial waste and the active ingredients of several drugs, can cause reduction or blockage in this enzyme's activity. This case causes the occurrence of anemia by damaging erythrocytes. In this study, the G6PD enzyme was purified 21,981 fold with affinity chromatography and the effects of the active ingredients of some antiarrhythmic drugs on enzyme activity were investigated with in vitro and in silico methods. We found that dobutamine hydrochloride significantly decreased enzyme activity and its inhibitory constant (K_i) value was calculated as 19.02 ± 4.83 mM. The in vitro study results also show that dobutamine hydrochloride is a potent inhibitor of enzyme activity. We also found that dobutamine hydrochloride inhibits the hG6PD enzyme's activity by causing structural alterations in substrate and coenzyme binding sites.Communicated by Ramaswamy H. Sarma.

Ascorbate sensitizes human osteosarcoma cells to the cytostatic effects of cisplatin

Osteosarcoma (OS) is the most common malignant bone tumor and a leading cause of cancer-related deaths in children and adolescents. Current standard treatments for OS are a combination of preoperative chemotherapy, surgical resection, and adjuvant chemotherapy. Cisplatin is used as the standard chemotherapeutic for OS treatment, but it induces various adverse effects, limiting its clinical application. Improving treatment efficacy without increasing the cisplatin dosage is desirable. In the present study, we assessed the combined effect of ascorbate on cisplatin treatment using cultured human OS cells. Co-treatment with ascorbate induced greater suppression of OS cell but not nonmalignant cell proliferation. The chemosensitizing effect of ascorbate on cisplatin treatment was tightly linked to ROS production. Altered cellular redox state due to increased ROS production modified glycolysis and mitochondrial function in OS cells. In addition, OS cell sphere formation was markedly decreased, suggesting that ascorbate increased the treatment efficacy of cisplatin against stem-like cells in the cancer cell population. We also found that enhanced MYC signaling, ribosomal biogenesis, glycolysis, and mitochondrial respiration are key signatures in OS cells with cisplatin resistance. Furthermore, cisplatin resistance was reversed by ascorbate. Taken together, our findings provide a rationale for combining cisplatin with ascorbate in therapeutic strategies against OS.

Di(2-ethylhexyl) phthalate inhibits glutathione regeneration and dehydrogenases of the pentose phosphate pathway on human colon carcinoma cells

Phthalates, particularly di(2-ethylhexyl) phthalate (DEHP), are compounds widely used as plasticizers and have become serious global contaminants. Because of the bioaccumulation of such substances, the food chain is at risk. The food contamination by some phthalates has been linked to different side effects in experimental animals. That is why we have chosen the intestinal system's cells which represent the primary targets of these compounds to test their toxic effects. Human colon carcinoma cells (HCT 116) were chosen to elucidate whether DEHP triggers oxidative stress and apoptosis. Our results indicated that DEHP is cytotoxic; it induces the overexpression of Hsp70 protein and causes oxidative damage through the generation of free radicals leading to lipid peroxidation induction and the increase of superoxide dismutase (SOD) and catalase (CAT) activities. In addition, cell treatment with DEHP resulted in a glutathione (GSH) content decrease and a decrease in the glutathione reductase (GR) activity. As new evidence provided in this study, we demonstrated that the DEHP affected the two enzymes' activities of the oxidative phase of the pentose phosphate pathway: Glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD). This leads to a decrease in the level of NADPH used by the GR to maintain the regeneration of the reduced GSH. We also demonstrated that such effects can be responsible for DEHP-induced apoptosis.

Epigenetic modification of the pentose phosphate pathway and the IGF-axis in women with gestational diabetes mellitus

Aim: Gestational diabetes mellitus (GDM) has been linked with adverse long-term health outcomes for the fetus and mother. These effects may be mediated by epigenetic modifications. Materials & methods: Genome-wide RNA sequencing was performed in placental tissue and maternal blood in six GDM and six non-GDM pregnancies. Promoter region DNA methylation was examined for selected genes and correlated with gene expression to examine an epigenetic modulator mechanism. Results: Reductions of mRNA expression and increases in promoter methylation were observed for G6PD in GDM women, and for genes encoding IGF-binding proteins in GDM-exposed placenta. Conclusion: GDM involves epigenetic attenuation of G6PD, which may lead to hyperglycemia and oxidative stress, and the IGF-axis, which may modulate fetal macrosomia.

The role of miR-122 in the dysregulation of glucose-6-phosphate dehydrogenase (G6PD) expression in hepatocellular cancer

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths worldwide. Thus, a better understanding of molecular aberrations involved in HCC pathogenesis is necessary for developing effective therapy. It is well established that cancer cells metabolize energy sources differently to rapidly generate biomass. Glucose-6-phosphate-dehydrogenase (G6PD), the rate-limiting enzyme of the Pentose Phosphate Pathway (PPP), is often activated in human malignancies to generate precursors for nucleotide and lipid synthesis. Here, we determined the clinical significance of G6PD in primary human HCC by analyzing RNA-seq and clinical data in The Cancer Genome Atlas. We found that the upregulation of G6PD correlates with higher tumor grade, increased tumor recurrence, and poor patient survival. Notably, liver-specific miR-122, which is essential for metabolic homeostasis, suppresses G6PD expression by directly interacting with its 3'UTR. Luciferase reporter assay confirmed two conserved functional miR-122 binding sites located in the 3'-UTR of G6PD. Furthermore, we show that ectopic expression of miR-122 and miR-1, a known regulator of G6PD expression coordinately repress G6PD expression in HCC cells. These miRNAs also reduced G6PD activity in HepG2 cells that express relatively high activity of this enzyme. Collectively, this study provides evidence that anti-HCC efficacy of miR122 and miR-1 could be mediated, at least in part, through inhibition of PPP by suppressing the expression of G6PD.

p53 and metabolism: from mechanism to therapeutics

The tumor cell changes itself and its microenvironment to adapt to different situations, including action of drugs and other agents targeting tumor control. Therefore, metabolism plays an important role in the activation of survival mechanisms to keep the cell proliferative potential. The Warburg effect directs the cellular metabolism towards an aerobic glycolytic pathway, despite the fact that it generates less adenosine triphosphate than oxidative phosphorylation; because it creates the building blocks necessary for cell proliferation. The transcription factor p53 is the master tumor suppressor; it binds to more than 4,000 sites in the genome and regulates the expression of more than 500 genes. Among these genes are important regulators of metabolism, affecting glucose, lipids and amino acids metabolism, oxidative phosphorylation, reactive oxygen species (ROS) generation and growth factors signaling. Wild-type and mutant p53 may have opposing effects in the expression of these metabolic genes. Therefore, depending on the p53 status of the cell, drugs that target metabolism may have different outcomes and metabolism may modulate drug resistance. Conversely, induction of p53 expression may regulate differently the tumor cell metabolism, inducing senescence, autophagy and apoptosis, which are dependent on the regulation of the PI3K/AKT/mTOR pathway and/or ROS induction. The interplay between p53 and metabolism is essential in the decision of cell fate and for cancer therapeutics.

Glucose 6-phosphate dehydrogenase and the kidney

PURPOSE OF REVIEW

Glucose 6-phosphate dehydrogenase (G6PD) is the rate-limiting enzyme of the pentose phosphate pathway. G6PD is the main source of the essential cellular reductant, NADPH. The purpose of this review is to describe the biochemistry of G6PD and NADPH, cellular factors that regulate G6PD, normal physiologic roles of G6PD, and the pathogenic role altered G6PD/NADPH plays in kidney disease.

RECENT FINDINGS

NADPH is required for many essential cellular processes such as the antioxidant system, nitric oxide synthase, cytochrome p450 enzymes, and NADPH oxidase. Decreased G6PD activity and, as a result, decreased NADPH level have been associated with diabetic kidney disease, altered nitric oxide production, aldosterone-mediated endothelial dysfunction, and dialysis-associated anemia. Increased G6PD activity is associated with all cancers including kidney cancer. Inherited G6PD deficiency is the most common mutation in the world that is thought to be a relatively mild disorder primarily associated with anemia. Yet, intriguing studies have shown an increased prevalence of diabetes mellitus in G6PD-deficient people. It is not known if G6PD-deficient people are at more risk for other diseases.

SUMMARY

Much more research needs to be done to determine the role of altered G6PD activity (inherited or acquired) in the pathogenesis of kidney disease.

Redox Status, Procoagulant Activity, and Metabolome of Fresh Frozen Plasma in Glucose 6-Phosphate Dehydrogenase Deficiency

OBJECTIVE

Transfusion of fresh frozen plasma (FFP) helps in maintaining the coagulation parameters in patients with acquired multiple coagulation factor deficiencies and severe bleeding. However, along with coagulation factors and procoagulant extracellular vesicles (EVs), numerous bioactive and probably donor-related factors (metabolites, oxidized components, etc.) are also carried to the recipient. The X-linked glucose 6-phosphate dehydrogenase deficiency (G6PD-), the most common human enzyme genetic defect, mainly affects males. By undermining the redox metabolism, the G6PD- cells are susceptible to the deleterious effects of oxidants. Considering the preferential transfusion of FFP from male donors, this study aimed at the assessment of FFP units derived from G6PD- males compared with control, to show whether they are comparable at physiological, metabolic and redox homeostasis levels.

METHODS

The quality of n = 12 G6PD- and control FFP units was tested after 12 months of storage, by using hemolysis, redox, and procoagulant activity-targeted biochemical assays, flow cytometry for EV enumeration and phenotyping, untargeted metabolomics, in addition to statistical and bioinformatics tools.

RESULTS

Higher procoagulant activity, phosphatidylserine positive EVs, RBC-vesiculation, and antioxidant capacity but lower oxidative modifications in lipids and proteins were detected in G6PD- FFP compared with controls. The FFP EVs varied in number, cell origin, and lipid/protein composition. Pathway analysis highlighted the riboflavin, purine, and glycerolipid/glycerophospholipid metabolisms as the most altered pathways with high impact in G6PD-. Multivariate and univariate analysis of FFP metabolomes showed excess of diacylglycerols, glycerophosphoinositol, aconitate, and ornithine but a deficiency in riboflavin, flavin mononucleotide, adenine, and arginine, among others, levels in G6PD- FFPs compared with control.

CONCLUSION

Our results point toward a different redox, lipid metabolism, and EV profile in the G6PD- FFP units. Certain FFP-needed patients may be at greatest benefit of receiving FFP intrinsically endowed by both procoagulant and antioxidant activities. However, the clinical outcome of G6PD- FFP transfusion would likely be affected by various other factors, including the signaling potential of the differentially expressed metabolites and EVs, the degree of G6PD-, the redox status in the recipient, the amount of FFP units transfused, and probably, the storage interval of the FFP, which deserve further investigation by future studies.

ID1 promotes hepatocellular carcinoma proliferation and confers chemoresistance to oxaliplatin by activating pentose phosphate pathway

Background

Drug resistance is one of the major concerns in the treatment of hepatocellular carcinoma (HCC). The aim of the present study was to determine whether aberrant high expression of the inhibitor of differentiation 1(ID1) confers oxaliplatin-resistance to HCC by activating the pentose phosphate pathway (PPP).

Methods

Aberrant high expression of ID1 was detected in two oxaliplatin-resistant cell lines MHCC97H–OXA(97H–OXA) and Hep3B–OXA(3B–OXA). The lentiviral shRNA or control shRNA was introduced into the two oxaliplatin-resistant cell lines. The effects of ID1 on cell proliferation, apoptosis and chemoresistance were evaluated in vitro and vivo. The molecular signaling mechanism underlying the induction of HCC proliferation and oxaliplatin resistance by ID1 was explored. The prognostic value of ID1/G6PD signaling in HCC patients was assessed using the Cancer Genome Atlas (TCGA) database.

Results

ID1 was upregulated in oxaliplaitin-resistant HCC cells and promoted HCC cell proliferation and oxaliplatin resistance. Silencing ID1 expression in oxaliplaitin-resistant HCC cell lines inhibited cell proliferation and sensitized oxaliplaitin-resistant cells to death. ID1 knockdown significantly decreased the expression of glucose-6-phosphate dehydrogenase (G6PD), a key enzyme of the PPP. Silencing ID1 expression blocked the activation of G6PD, decreased the production of PPP NADPH, and augmented reactive oxygen and species (ROS), thus inducing cell apoptosis. Study of the molecular mechanism showed that ID1 induced G6PD promoter transcription and activated PPP through Wnt/β-catenin/c-MYC signaling. In addition, ID1/G6PD signaling predicted unfavorable prognosis of HCC patients on the basis of TCGA.

Conclusions

Our study provided the first evidence that ID1 conferred oxaliplatin resistance in HCC by activating the PPP. This newly defined pathway may have important implications in the research and development of new more effective anti-cancer drugs.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0637-7) contains supplementary material, which is available to authorized users.

G6PD plays a neuroprotective role in brain ischemia through promoting pentose phosphate pathway

TIGAR-regulated pentose phosphate pathway (PPP) plays a critical role in the neuronal survival during cerebral ischemia/reperfusion. Glucose-6-phosphate dehydrogenase (G6PD) is a rate-limiting enzyme in PPP and thus, we hypothesized that it plays an essential role in anti-oxidative defense through producing NADPH. The present study investigated the regulation and the role of G6PD in ischemia/reperfusion-induced neuronal injury with in vivo and in vitro models of ischemic stroke. The results showed that the levels of G6PD mRNA and protein were increased after ischemia/reperfusion. In vivo, lentivirus-mediated G6PD overexpression in mice markedly reduced neuronal damage after ischemia/reperfusion insult, while lentivirus-mediated G6PD knockdown exacerbated it. In vitro, overexpression of G6PD in cultured primary neurons decreased neuronal injury under oxygen and glucose deprivation/reoxygenation (OGD/R) condition, whereas knockdown of G6PD aggravated it. Overexpression of G6PD increased levels of NADPH and reduced form of glutathione (rGSH), and ameliorated ROS-induced macromolecular damage. On the contrary, knockdown of G6PD executed the opposite effects in mice and in primary neurons. Supplementation of exogenous NADPH alleviated the detrimental effects of G6PD knockdown, whereas further enhanced the beneficial effects of G6PD overexpression in ischemic injury. Therefore, our results suggest that G6PD protects ischemic brain injury through increasing PPP. Thus G6PD may be considered as potential therapeutic target for treatment of ischemic brain injury.

Melatonin Decreases Glucose Metabolism in Prostate Cancer Cells: A 13C Stable Isotope-Resolved Metabolomic Study

The pineal neuroindole melatonin exerts an exceptional variety of systemic functions. Some of them are exerted through its specific membrane receptors type 1 and type 2 (MT1 and MT2) while others are mediated by receptor-independent mechanisms. A potential transport of melatonin through facilitative glucose transporters (GLUT/SLC2A) was proposed in prostate cancer cells. The prostate cells have a particular metabolism that changes during tumor progression. During the first steps of carcinogenesis, oxidative phosphorylation is reactivated while the switch to the “Warburg effect” only occurs in advanced tumors and in the metastatic stage. Here, we investigated whether melatonin might change prostate cancer cell metabolism. To do so, ¹³C stable isotope-resolved metabolomics in androgen sensitive LNCaP and insensitive PC-3 prostate cancer cells were employed. In addition to metabolite ¹³C-labeling, ATP/AMP levels, and lactate dehydrogenase or pentose phosphate pathway activity were measured. Melatonin reduces lactate labeling in androgen-sensitive cells and it also lowers ¹³C-labeling of tricarboxylic acid cycle metabolites and ATP production. In addition, melatonin reduces lactate ¹³C-labeling in androgen insensitive prostate cancer cells. Results demonstrated that melatonin limits glycolysis as well as the tricarboxylic acid cycle and pentose phosphate pathway in prostate cancer cells, suggesting that the reduction of glucose uptake is a major target of the indole in this tumor type.

Anti-inflammatory and antioxidant role of resveratrol on nicotine-induced lung changes in male rats

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Nicotine decreased the antioxidant capacities in male rats.

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The lung of nicotine-treated rats showed severe congestion of the alveolar lung tissues.

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Resveratrol exerts its protective effect by alleviating the extent of oxidative status induced by nicotine.

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Resveratrol improve the enzymatic/non-enzymatic antioxidant defense system in rats treated with combination of nicotine and resveratrol.

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Resveratrol decreases the pathological changes in animals against the lung damage caused by nicotine.

Male albino rats of Wistar strain were injected intraperitoneally with nicotine or/and resveratrol for 4 weeks. Serum Interleukin-2, Interleukin-6, alpha-fetoprotein and tumor necrosis-alpha, as well as plasma 8-hydroxydeoxyguanosine of nicotine-treated rats were increased significantly. Myeloperoxidase, xanthine oxidase, nitric oxide, lipid peroxidation and total oxidative status of the lung in nicotine-treated rats were increased significantly, which were brought down to normal in resveratrol co-treated group. Endogenous antioxidant status as the activity of superoxide dismutase, catalase, glutathione peroxidase, and glucose-6-phosphate dehydrogenases were found to be decreased significantly in the lung of the nicotine-treated group, which were significantly raised in resveratrol-administered groups. The non-enzymatic antioxidants as total antioxidant and thiol levels were decreased significantly as the effect of nicotine that was effectively enhanced by resveratrol treatment. The lung of nicotine-treated rats showed severe congestion of the alveolar lung tissues with scattered congestion per bronchiolar and perivascular cells, as well as, inflammatory cells were observed. The data suggested that resveratrol exerts its protective effect by modulating the extent of oxidative status and improving the enzymatic/non-enzymatic antioxidant defense system, moreover, decreases the pathological changes in animals against the lung damage caused by nicotine.

Data mining and pathway analysis of glucose-6-phosphate dehydrogenase with natural language processing

Human glucose-6-phosphate dehydrogenase (G6PD) is a crucial enzyme in the pentose phosphate pathway, and serves an important role in biosynthesis and the redox balance. G6PD deficiency is a major cause of neonatal jaundice and acute hemolyticanemia, and recently, G6PD has been associated with diseases including inflammation and cancer. The aim of the present study was to conduct a search of the National Center for Biotechnology Information PubMed library for articles discussing G6PD. Genes that were identified to be associated with G6PD were recorded, and the frequency at which each gene appeared was calculated. Gene ontology (GO), pathway and network analyses were then performed. A total of 98 G6PD‑associated genes and 33 microRNAs (miRNAs) that potentially regulate G6PD were identified. The 98 G6PD‑associated genes were then sub‑classified into three functional groups by GO analysis, followed by analysis of function, pathway, network, and disease association. Out of the 47 signaling pathways identified, seven were significantly correlated with G6PD‑associated genes. At least two out of four independent programs identified the 33 miRNAs that were predicted to target G6PD. miR‑1207‑5P, miR‑1 and miR‑125a‑5p were predicted by all four software programs to target G6PD. The results of the present study revealed that dysregulation of G6PD was associated with cancer, autoimmune diseases, and oxidative stress‑induced disorders. These results revealed the potential roles of G6PD‑regulated signaling and metabolic pathways in the etiology of these diseases.

Induction of metastasis, cancer stem cell phenotype, and oncogenic metabolism in cancer cells by ionizing radiation

Radiation therapy is one of the major tools of cancer treatment, and is widely used for a variety of malignant tumours. Radiotherapy causes DNA damage directly by ionization or indirectly via the generation of reactive oxygen species (ROS), thereby destroying cancer cells. However, ionizing radiation (IR) paradoxically promotes metastasis and invasion of cancer cells by inducing the epithelial-mesenchymal transition (EMT). Metastasis is a major obstacle to successful cancer therapy, and is closely linked to the rates of morbidity and mortality of many cancers. ROS have been shown to play important roles in mediating the biological effects of IR. ROS have been implicated in IR-induced EMT, via activation of several EMT transcription factors—including Snail, HIF-1, ZEB1, and STAT3—that are activated by signalling pathways, including those of TGF-β, Wnt, Hedgehog, Notch, G-CSF, EGFR/PI3K/Akt, and MAPK. Cancer cells that undergo EMT have been shown to acquire stemness and undergo metabolic changes, although these points are debated. IR is known to induce cancer stem cell (CSC) properties, including dedifferentiation and self-renewal, and to promote oncogenic metabolism by activating these EMT-inducing pathways. Much accumulated evidence has shown that metabolic alterations in cancer cells are closely associated with the EMT and CSC phenotypes; specifically, the IR-induced oncogenic metabolism seems to be required for acquisition of the EMT and CSC phenotypes. IR can also elicit various changes in the tumour microenvironment (TME) that may affect invasion and metastasis. EMT, CSC, and oncogenic metabolism are involved in radioresistance; targeting them may improve the efficacy of radiotherapy, preventing tumour recurrence and metastasis. This study focuses on the molecular mechanisms of IR-induced EMT, CSCs, oncogenic metabolism, and alterations in the TME. We discuss how IR-induced EMT/CSC/oncogenic metabolism may promote resistance to radiotherapy; we also review efforts to develop therapeutic approaches to eliminate these IR-induced adverse effects.

Glucose-6-phosphate dehydrogenase deficiency does not increase the susceptibility of sperm to oxidative stress induced by H2O2

Objective

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common human enzyme defect. G6PD plays a key role in the pentose phosphate pathway, which is a major source of nicotinamide adenine dinucleotide phosphate (NADPH). NADPH provides the reducing equivalents for oxidation-reduction reductions involved in protecting against the toxicity of reactive oxygen species such as H₂O₂. We hypothesized that G6PD deficiency may reduce the amount of NADPH in sperms, thereby inhibiting the detoxification of H₂O₂, which could potentially affect their motility and viability, resulting in an increased susceptibility to infertility.

Methods

Semen samples were obtained from four males with G6PD deficiency and eight healthy males as a control. In both groups, motile sperms were isolated from the seminal fluid and incubated with 0, 10, 20, 40, 60, 80, and 120 µM concentrations of H₂O₂. After 1 hour incubation at 37℃, sperms were evaluated for motility and viability.

Results

Incubation of sperms with 10 and 20 µM H₂O₂ led to very little decrease in motility and viability, but motility decreased notably in both groups in 40, 60, and 80 µM H₂O₂, and viability decreased in both groups in 40, 60, 80, and 120 µM H₂O₂. However, no statistically significant differences were found between the G6PD-deficient group and controls.

Conclusion

G6PD deficiency does not increase the susceptibility of sperm to oxidative stress induced by H₂O₂, and the reducing equivalents necessary for protection against H₂O₂ are most likely produced by other pathways. Therefore, G6PD deficiency cannot be considered as major risk factor for male infertility.

Effect of Deep Intramuscular Stimulation and Transcranial Magnetic Stimulation on Neurophysiological Biomarkers in Chronic Myofascial Pain Syndrome

OBJECTIVE

The aim was to assess the neuromodulation techniques effects (repetitive transcranial magnetic stimulation [rTMS] and deep intramuscular stimulation therapy [DIMST]) on pain intensity, peripheral, and neurophysiological biomarkers chronic myofascial pain syndrome (MPS) patients.

DESIGN

Randomized, double blind, factorial design, and controlled placebo-sham clinical trial.

SETTING

Clinical trial in the Laboratory of Pain and Neuromodulation at Hospital de Clínicas de Porto Alegre (NCT02381171).

SUBJECTS

We recruited women aged between 19- and 75-year old, with MPS diagnosis.

METHODS

Patients were randomized into four groups: rTMS + DIMST, rTMS + sham-DIMST, sham-rTMS + DIMST, sham-rTMS + sham-DIMST; and received 10 sessions for 20 minutes each one (rTMS and DIMST). Pain was assessed by visual analogue scale (VAS); neurophysiological parameters were assessed by transcranial magnetic stimulation; biochemical parameters were: BDNF, S100β, lactate dehydrogenase, inflammatory (TNF-α, IL6, and IL10), and oxidative stress parameters.

RESULTS

We observed the pain relief assessed by VAS immediately assessed before and after the intervention (P < 0.05, F(1,3)= 3.494 and F(1,3)= 4.656, respectively); in the sham-rTMS + DIMST group and both three active groups in relation to sham-rTMS + sham-DIMST group, respectively. There was an increase in the MEP after rTMS + sham-DIMST (P < 0.05). However, there was no change in all-peripheral parameters analyzed across the treatment (P > 0.05).

CONCLUSION

Our findings add additional evidence about rTMS and DIMST in relieving pain in MPS patients without synergistic effect. No peripheral biomarkers reflected the analgesic effect of both techniques; including those related to cellular damage. Additionally, one neurophysiological parameter (increased MEP amplitude) needs to be investigated.

Cell-derived microparticles after exercise in individuals with G6PD Viangchan

Glucose-6-phospate dehydrogenase (G6PD) deficient cells are sensitive to oxidative damage leading to the formation of microparticles (MPs). Therefore, we examined the concentration of MPs and changes in the antioxidant balance after an acute strenuous exercise (SEx) and moderate-intensity exercise (MEx). Eighteen healthy females (18-24 years) with G6PD normal and eighteen age-matched females with G6PD Viangchan (871G>A) were tested by running on a treadmill at their maximal oxygen uptake for SEx and at 75% of their maximal heart rate for MEx. It was found that SEx triggered the release of total microparticles (TTMPs) above baseline levels and remained significantly higher 45 minutes after the exercise in G6PD normal individuals. However, SEx-induced increase in TTMPs was significantly higher in G6PD Viangchan as compared to G6PD normal. In contrast, MEx did not to alter the release of TTMPs in both G6PD normal and Viangchan. Moreover, TTMPs concentrations were inversely correlated with G6PD activity (r =-0.82, P <  0.05) but positively correlated with MDA concentrations (r = 0.74, P <  0.05). Using cell specific antibodies, we determined that MPs were mainly derived from platelets and erythrocytes. Altogether, the present study indicates that G6PD Viangchan may participate in MEx without higher MPs concentration and oxidative stress compared with G6PD normal.

Understanding central carbon metabolism of rapidly proliferating mammalian cells based on analysis of key enzymatic activities in GS-CHO cell lines

The central carbon metabolism (glycolysis, the pentose phosphate pathway [PPP], and the tricarboxylic acid [TCA] cycle) plays an essential role in the supply of biosynthetic precursors and energy. How the central carbon metabolism changes with the varying growth rates in the in vitro cultivation of rapidly proliferating mammalian cells, such as cancer cells and continuous cell lines for recombinant protein production, remains elusive. Based on relationships between the growth rate and the activity of seven key enzymes from six cell clones, this work reports finding an important metabolic characteristic in rapidly proliferating glutamine synthetase-Chinese hamster ovary cells. The key enzymatic activity involved in the TCA cycle that is responsible for the supply of energy became elevated as the growth rate exhibited increases, while the activity of key enzymes in metabolic pathways (glycolysis and the PPP), responsible for the supply of biosynthetic precursors, tended to decrease-suggesting that rapidly proliferating cells still depended predominantly on the TCA cycle rather than on aerobic glycolysis for their energetic demands. Meanwhile, the growth-limiting resource was most likely biosynthetic substrates rather than energy provision. In addition, the multifaceted role of glucose-6-phosphate isomerase (PGI) was confirmed, based on a significant correlation between PGI activity and the percentage of G2/M-phase cells.

Identification of targets of miRNA-221 and miRNA-222 in fulvestrant-resistant breast cancer

The present study aimed to identify the differentially expressed genes (DEGs) regulated by microRNA (miRNA)-221 and miRNA-222 that are associated with the resistance of breast cancer to fulvestrant. The GSE19777 transcription profile was downloaded from the Gene Expression Omnibus database, and includes data from three samples of antisense miRNA-221-transfected fulvestrant-resistant MCF7-FR breast cancer cells, three samples of antisense miRNA-222-transfected fulvestrant-resistant MCF7-FR cells and three samples of control inhibitor (green fluorescent protein)-treated fulvestrant-resistant MCF7-FR cells. The linear models for microarray data package in R/Bioconductor was employed to screen for DEGs in the miRNA-transfected cells, and the pheatmap package in R was used to perform two-way clustering. Pathway enrichment was conducted using the Gene Set Enrichment Analysis tool. Furthermore, a miRNA-messenger (m) RNA regulatory network depicting interactions between miRNA-targeted upregulated DEGs was constructed and visualized using Cytoscape. In total, 492 and 404 DEGs were identified for the antisense miRNA-221-transfected MCF7-FR cells and the antisense miRNA-222-transfected MCF7-FR cells, respectively. Genes of the pentose phosphate pathway (PPP) were significantly enriched in the antisense miRNA-221-transfected MCF7-FR cells. In addition, components of the Wnt signaling pathway and cell adhesion molecules (CAMs) were significantly enriched in the antisense miRNA-222-transfected MCF7-FR cells. In the miRNA-mRNA regulatory network, miRNA-222 was demonstrated to target protocadherin 10 (PCDH10). The results of the present study suggested that the PPP and Wnt signaling pathways, as well as CAMs and PCDH10, may be associated with the resistance of breast cancer to fulvestrant.

Geissoschizine methyl ether protects oxidative stress-mediated cytotoxicity in neurons through the 'Neuronal Warburg Effect'

ETHNOPHARMACOLOGICAL RELEVANCE

The rate of production of reactive oxygen species (ROS) is determined by mitochondrial metabolic rate. In turn, excessive ROS damage mitochondrial function, which is linked to aging and neurodegenerative conditions. One possible path to prevent oxidative stress could be achieved by reducing mitochondrial respiration in favor of less efficient ATP production via glycolysis. Such a shift in energy metabolism is known as the 'Warburg effect'. Geissoschizine methyl ether (GM) is one of the active components responsible for the psychotropic effects of Yokukansan, an herbal preparation widely used in China and Japan.

AIM OF THE STUDY

GM protects neurons from glutamate-induced oxidative cytotoxicity through regulating mitochondrial function and suppressing ROS generation. We investigated the protective mechanism of GM against glutamate-induced oxidative stress in neuronal cells.

MATERIALS AND METHODS

The current study was performed on primary neurons and HT22 cells, a hippocampus neuronal cell line. Cell viability was measured by Calcein AM assay. H2DCFDA staining was used for intracellular ROS measurement. GSH level was measured using the GSH-Glo™ luminescence-based assay. Mitochondrial respiration and glycolysis were measured by the Seahorse Bioscience XFe 96 Extracellular Flux Analyzer. Protein levels were analyzed by western blot analysis.

RESULTS

GM prevented glutamate-induced cytotoxicity in an HT-22 neuronal cell line even with a 9-hour exposure delay. GM blocked glutamate-induced intracellular ROS accumulation through suppressing mitochondrial respiration. Further, we found that GM up-regulated glycolysis and the pentose-phosphate pathway, which is involved in the production of intracellular reducing agent, NADPH. In addition, GM protected primary cortical neurons from both glutamate and buthioninesulfoximine toxicity.

CONCLUSION

GM prevents glutamate-induced oxidative damage through reducing mitochondrial respiration, which further suppresses ROS generation. In addition, GM up-regulates glycolysis which compensate for the energy depletion induced by mitochondrial respiration inhibition. Overall, our study is the first to report that GM protects neurons from oxidative toxicity by shifting energy metabolism from mitochondrial respiration to glycolysis.

Muscle wasting and aging: Experimental models, fatty infiltrations, and prevention

Identification of cost-effective interventions to maintain muscle mass, muscle strength, and physical performance during muscle wasting and aging is an important public health challenge. It requires understanding of the cellular and molecular mechanisms involved. Muscle-deconditioning processes have been deciphered by means of several experimental models, bringing together the opportunities to devise comprehensive analysis of muscle wasting. Studies have increasingly recognized the importance of fatty infiltrations or intermuscular adipose tissue for the age-mediated loss of skeletal-muscle function and emphasized that this new important factor is closely linked to inactivity. The present review aims to address three main points. We first mainly focus on available experimental models involving cell, animal, or human experiments on muscle wasting. We next point out the role of intermuscular adipose tissue in muscle wasting and aging and try to highlight new findings concerning aging and muscle-resident mesenchymal stem cells called fibro/adipogenic progenitors by linking some cellular players implicated in both FAP fate modulation and advancing age. In the last part, we review the main data on the efficiency and molecular and cellular mechanisms by which exercise, replacement hormone therapies, and β-hydroxy-β-methylbutyrate prevent muscle wasting and sarcopenia. Finally, we will discuss a potential therapeutic target of sarcopenia: glucose 6-phosphate dehydrogenase.

Purification of glucose-6-phosphate dehydrogenase and glutathione reductase enzymes from the gill tissue of Lake Van fish and analyzing the effects of some chalcone derivatives on enzyme activities

Glucose-6-phosphate dehydrogenase (G6PD) and glutathione reductase (GR) are metabolically quite important enzymes. Within this study, these two enzymes were purified for the first time from the gills of Lake Van fish. In the purifying process, ammonium sulfate precipitation and 2',5'-ADP Sepharose 4B affinity column chromatography techniques for glucose-6-phosphate dehydrogenase, temperature degradation and 2',5'-ADP Sepharose 4B affinity column chromatography for glutathione reductase enzyme were used. The control of the enzyme purity and determination of molecular weight were done with sodium dodecyl sulfate polyacrylamide gel electrophoresis. K(M) and V(max) values were determined with Lineweaver-Burk plot. Besides, the effects of some chalcone derivatives on the purified enzymes were analyzed. For the ones showing inhibition effect, % activity-[I] figures were drawn and IC50 values were determined. K(i) value was calculated by using Cheng-Prusoff equation.

Succinate dehydrogenase activity regulates PCB3-quinone-induced metabolic oxidative stress and toxicity in HaCaT human keratinocytes

Polychlorinated biphenyls (PCBs) and their metabolites are environmental pollutants that are known to have adverse health effects. 1-(4-Chlorophenyl)-benzo-2,5-quinone (4-ClBQ), a quinone metabolite of 4-monochlorobiphenyl (PCB3, present in the environment and human blood) is toxic to human skin keratinocytes, and breast and prostate epithelial cells. This study investigates the hypothesis that 4-ClBQ-induced metabolic oxidative stress regulates toxicity in human keratinocytes. Results from Seahorse XF96 Analyzer showed that the 4-ClBQ treatment increased extracellular acidification rate, proton production rate, oxygen consumption rate and ATP content, indicative of metabolic oxidative stress. Results from a q-RT-PCR assay showed significant increases in the mRNA levels of hexokinase 2 (hk2), pyruvate kinase M2 (pkm2) and glucose-6-phosphate dehydrogenase (g6pd), and decreases in the mRNA levels of succinate dehydrogenase (complex II) subunit C and D (sdhc and sdhd). Pharmacological inhibition of G6PD-activity enhanced the toxicity of 4-ClBQ, suggesting that the protective function of the pentose phosphate pathway is functional in 4-ClBQ-treated cells. The decrease in sdhc and sdhd expression was associated with a significant decrease in complex II activity and increase in mitochondrial levels of ROS. Overexpression of sdhc and sdhd suppressed 4-ClBQ-induced inhibition of complex II activity, increase in mitochondrial levels of ROS, and toxicity. These results suggest that the 4-ClBQ treatment induces metabolic oxidative stress in HaCaT cells, and while the protective function of the pentose phosphate pathway is active, inhibition of complex II activity sensitizes HaCaT cells to 4-ClBQ-induced toxicity.

6-Phosphogluconate dehydrogenase links oxidative PPP, lipogenesis and tumour growth by inhibiting LKB1-AMPK signalling

The oxidative pentose phosphate pathway (PPP) contributes to tumor growth, but the precise contribution of 6-phosphogluconate dehydrogenase (6PGD), the third enzyme in this pathway, to tumorigenesis remains unclear. We found that suppression of 6PGD decreased lipogenesis and RNA biosynthesis and elevated ROS levels in cancer cells, attenuating cell proliferation and tumor growth. 6PGD-mediated production of ribulose-5-phosphate (Ru-5-P) inhibits AMPK activation by disrupting the active LKB1 complex, thereby activating acetyl-CoA carboxylase 1 and lipogenesis. Ru-5-P and NADPH are thought to be precursors in RNA biosynthesis and lipogenesis, respectively; thus, our findings provide an additional link between oxidative PPP and lipogenesis through Ru-5-P-dependent inhibition of LKB1-AMPK signaling. Moreover, we identified and developed 6PGD inhibitors, Physcion and its derivative S3, that effectively inhibited 6PGD, cancer cell proliferation and tumor growth in nude mice xenografts without obvious toxicity, suggesting that 6PGD could be an anticancer target.

Cross-omics comparison of stress responses in mesothelial cells exposed to heat- versus filter-sterilized peritoneal dialysis fluids

Recent research suggests that cytoprotective responses, such as expression of heat-shock proteins, might be inadequately induced in mesothelial cells by heat-sterilized peritoneal dialysis (PD) fluids. This study compares transcriptome data and multiple protein expression profiles for providing new insight into regulatory mechanisms. Two-dimensional difference gel electrophoresis (2D-DIGE) based proteomics and topic defined gene expression microarray-based transcriptomics techniques were used to evaluate stress responses in human omental peritoneal mesothelial cells in response to heat- or filter-sterilized PD fluids. Data from selected heat-shock proteins were validated by 2D western-blot analysis. Comparison of proteomics and transcriptomics data discriminated differentially regulated protein abundance into groups depending on correlating or noncorrelating transcripts. Inadequate abundance of several heat-shock proteins following exposure to heat-sterilized PD fluids is not reflected on the mRNA level indicating interference beyond transcriptional regulation. For the first time, this study describes evidence for posttranscriptional inadequacy of heat-shock protein expression by heat-sterilized PD fluids as a novel cytotoxic property. Cross-omics technologies introduce a novel way of understanding PDF bioincompatibility and searching for new interventions to reestablish adequate cytoprotective responses.

Hypoxia, cancer metabolism and the therapeutic benefit of targeting lactate/H(+) symporters

Since Otto Warburg reported the 'addiction' of cancer cells to fermentative glycolysis, a metabolic pathway that provides energy and building blocks, thousands of studies have shed new light on the molecular mechanisms contributing to altered cancer metabolism. Hypoxia, through hypoxia-inducible factors (HIFs), in addition to oncogenes activation and loss of tumour suppressors constitute major regulators of not only the "Warburg effect" but also many other metabolic pathways such as glutaminolysis. Enhanced glucose and glutamine catabolism has become a recognised feature of cancer cells, leading to accumulation of metabolites in the tumour microenvironment, which offers growth advantages to tumours. Among these metabolites, lactic acid, besides imposing an acidic stress, is emerging as a key signalling molecule that plays a pivotal role in cancer cell migration, angiogenesis, immune escape and metastasis. Although interest in lactate for cancer development only appeared recently, pharmacological molecules blocking its metabolism are already in phase I/II clinical trials. Here, we review the metabolic pathways generating lactate, and we discuss the rationale for targeting lactic acid transporter complexes for the development of efficient and selective anticancer therapies.

Oxidant and antioxidant status in experimental rat testis after testicular torsion/detorsion

BACKGROUND

The aim of this study was to determine oxidative stress (OS) parameters after testicular torsion/detorsion in adult rats.

MATERIALS AND METHODS

In this experimental study, male adult Wistar rats were divided into four groups, each consisting of seven animals: group I-one hour right testicular torsion with subsequent orchiectomy, group II-one hour right testicular torsion followed by detorsion, group III-unilateral right-sided orchiectomy without previous torsion and group IV-control. After 30 days, bilateral orchiectomies were performed in rats with both testes and unilateral orchiectomies in rats with single testicles. Parameters of OS were determined in testicular tissue and in plasma.

RESULTS

Plasma concentrations of advanced oxidation protein products (AOPP) and thiobarbituric acid reactive substances (TBARS) were higher (p<0.05 and p<0.01, respectively), whilst the plasma concentration of the total sulfhydryl (T-SH)-groups was lower (p<0.05) in group I compared to the control group. Group II had higher plasma concentrations of AOPP compared to group IV (p<0.05), as well as significantly increased TBARS and decreased T-SH-group levels compared to groups III (p<0.05 and p<0.01, respectively) and IV (p<0.01, for both parameters). There were significant differences in OS markers between the ipsilateral and contralateral testis, as well as significant correlations among levels of both plasma and tissue markers of OS.

CONCLUSION

The increase in TBARS levels seen throughout the experimental period indicated that OS development was caused by ischemia/reperfusion in the testicular tissue. The oxidant-antioxidant system of the testicular tissue was altered during torsion as well as detorsion.

Comparison of the anti-diabetic effects of resveratrol, gliclazide and losartan in streptozotocin-induced experimental diabetes

AIM

The aim of this study was to compare the effect of the resveratrol with gliclazide and losartan in streptozotocin induced diabetic rats.

MATERIALS AND METHODS

Adult male Wistar albino rats were divided into five groups of seven rats each. Diabetes was induced with a single intraperitoneal (i.p.) injection of streptozotocin (55 mg/kg). Rats with blood glucose levels above 250 mg/dl after 48 h of streptozotocin injection were included in the diabetic group. Gliclazide and resveratrol were administered for 3 weeks at 5 mg/kg per day and losartan was administered for 3 weeks at 30 mg/kg per day in an oral aqueous suspension. At the end of the third week all rats were euthanized and fasting blood glucose, HbA1c and the metabolic activity of the hepatic enzymes hexokinase and glucose-6 phosphate dehydrogenase were measured in tail blood and liver specimens. All parameters were quantified using an ELISA plate reader.

RESULTS

Resveratrol and gliclazide significantly reduced both blood glucose levels and HbA1c levels in diabetic rats (p < 0.001). However, losartan did not exhibit the same effects (p < 0.05). The enzymatic activity of the liver enzymes hexokinase, glucose-6 phosphate dehydrogenase, fructose 1,6-biphosphatase, pyruvate kinase and glucose-6 phosphatase were enhanced by resveratrol and gliclazide, while losartan treatment was not associated with significant changes in liver carbohydrate metabolism.

CONCLUSION

Resveratrol was not effective in improving liver carbohydrate metabolism relative to gliclazide, a drug widely used to treat diabetes. Dose-response profile of resveratrol remains indeterminate and additional studies may be necessary to determine effective dosing in diabetes.

TP53-induced glycolysis and apoptosis regulator promotes proliferation and invasiveness of nasopharyngeal carcinoma cells

The TP53-induced glycolysis and apoptosis regulator (TIGAR) is the protein product of the p53 target gene, C12orf5. TIGAR blocks glycolysis and promotes cellular metabolism via the pentose phosphate pathway; it promotes the production of cellular nicotinamide adenine dinucleotide phosphate (NADPH), which leads to enhanced scavenging of intracellular reactive oxygen species, and inhibition of oxidative stress-induced apoptosis in normal cells. Our previous study identified a novel nucleoside analog that inhibited cellular growth and induced apoptosis in nasopharyngeal carcinoma (NPC) cell lines via downregulation of TIGAR expression. Furthermore, the growth inhibitory effects of c-Met tyrosine kinase inhibitors were ameliorated by the overexpression of TIGAR in the NPC cell lines. These results indicate a significant role for TIGAR expression in the survival of NPCs. The present study aimed to further define the function of TIGAR expression in NPC cells. In total, 36 formalin-fixed, paraffin-embedded NPC tissue samples were obtained for the immunohistochemical determination of TIGAR expression. The effects of TIGAR expression on cell proliferation, NADPH production and cellular invasiveness were also assessed in NPC cell lines. Overall, TIGAR was overexpressed in 27/36 (75%) of the NPC tissues compared with the adjacent non-cancer epithelial cells. Similarly, TIGAR overexpression was also observed in a panel of six NPC cell lines compared with normal NP460 hTert and Het1A cell lines. TIGAR overexpression led to increased cellular growth, NADPH production and invasiveness of the NPC cell lines, whereas a knockdown of TIGAR expression resulted in significant inhibition of cellular growth and invasiveness. The expression of the two mesenchymal markers, fibronectin and vimentin, was increased by TIGAR overexpression, but reduced following TIGAR-knockdown. The present study revealed that TIGAR overexpression led to increased cellular growth, NADPH production and invasiveness, and the maintenance of a mesenchymal phenotype, in NPC tissues.

Combined inhibition of glycolysis, the pentose cycle, and thioredoxin metabolism selectively increases cytotoxicity and oxidative stress in human breast and prostate cancer

Inhibition of glycolysis using 2-deoxy-d-glucose (2DG, 20 mM, 24–48 h) combined with inhibition of the pentose cycle using dehydroepiandrosterone (DHEA, 300 µM, 24–48 h) increased clonogenic cell killing in both human prostate (PC-3 and DU145) and human breast (MDA-MB231) cancer cells via a mechanism involving thiol-mediated oxidative stress. Surprisingly, when 2DG+DHEA treatment was combined with an inhibitor of glutathione (GSH) synthesis (l-buthionine sulfoximine; BSO, 1 mM) that depleted GSH>90% of control, no further increase in cell killing was observed during 48 h exposures. In contrast, when an inhibitor of thioredoxin reductase (TrxR) activity (Auranofin; Au, 1 µM), was combined with 2DG+DHEA or DHEA-alone for 24 h, clonogenic cell killing was significantly increased in all three human cancer cell lines. Furthermore, enhanced clonogenic cell killing seen with the combination of DHEA+Au was nearly completely inhibited using the thiol antioxidant, N-acetylcysteine (NAC, 20 mM). Redox Western blot analysis of PC-3 cells also supported the conclusion that thioredoxin-1 (Trx-1) oxidation was enhanced by treatment DHEA+Au and inhibited by NAC. Importantly, normal human mammary epithelial cells (HMEC) were not as sensitive to 2DG, DHEA, and Au combinations as their cancer cell counterparts (MDA-MB-231). Overall, these results support the hypothesis that inhibition of glycolysis and pentose cycle activity, combined with inhibition of Trx metabolism, may provide a promising strategy for selectively sensitizing human cancer cells to oxidative stress-induced cell killing.

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Inhibition of both glycolysis and pentose cycle causes oxidative stress in human breast and prostate cancer cells.

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Combining inhibition of glycolysis and pentose cycle with inhibition of thioredoxin reductase enhances cell killing of these human cancer cells.

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The toxicity and oxidative stress is selective for cancer vs. normal cells.

The Warburg effect revisited--lesson from the Sertoli cell

Otto Warburg observed that cancerous cells prefer fermentative instead of oxidative metabolism of glucose, although the former is in theory less efficient. Since Warburg's pioneering works, special attention has been given to this difference in cell metabolism. The Warburg effect has been implicated in cell transformation, immortalization, and proliferation during tumorigenesis. Cancer cells display enhanced glycolytic activity, which is correlated with high proliferation, and thus, glycolysis appears to be an excellent candidate to target cancer cells. Nevertheless, little attention has been given to noncancerous cells that exhibit a "Warburg-like" metabolism with slight, but perhaps crucial, alterations that may provide new directions to develop new and effective anticancer therapies. Within the testis, the somatic Sertoli cell (SC) presents several common metabolic features analogous to cancer cells, and a clear "Warburg-like" metabolism. Nevertheless, SCs actively proliferate only during a specific time period, ceasing to divide in most species after puberty, when they become terminally differentiated. The special metabolic features of SC, as well as progression from the immature but proliferative state, to the mature nonproliferative state, where a high glycolytic activity is maintained, make these cells unique and a good model to discuss new perspectives on the Warburg effect. Herein we provide new insight on how the somatic SC may be a source of new and exciting information concerning the Warburg effect and cell proliferation.

Expression of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in oxidative stress induced by long-term iron toxicity in rat liver

Reactive oxygen species (ROS) are highly reactive and oxygen-containing molecules that are derived by metabolic activities or from environmental sources. Toxicity of heavy metals including iron has the ability to generate ROS in all living organisms. The pentose phosphate pathway enzymes, which are glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, produce nicotinamide adenine dinucleotide phosphate (NADPH) that enables cells to counterbalance the oxidative stress via the action of the glutathione system. The results presented here have shown that toxic and nontoxic levels of iron have a strong effect on the expression of both genes. While toxic levels of iron exhibited significant changes in enzyme activity, nontoxic levels had no effect on enzymes in rat liver. Our results are the first evidence to elucidate how oxidative stress induced by long-term iron toxicity affects both enzymes at the enzymatic and molecular level and also to determine any possible correlation between the enzymatic and molecular levels.