Inhibition Of Glucose-6-phosphate Dehydrogenase Research Articles

In Silico Approach for Assessment of the Anti-tumor Potential of Cannabinoid Compounds by Targeting Glucose-6-phosphate Dehydrogenase Enzyme.

Glucose-6-phosphate dehydrogenase (G6PD) is a pentose phosphate pathway (PPP) enzyme that generates NADPH, which is required for cellular redox equilibrium and reductive biosynthesis. It has been demonstrated that abnormal G6PD activation promotes cancer cell proliferation and metastasis. To date, no G6PD inhibitor has passed clinical testing successfully enough to be launched as a medicine. As a result, in this investigation, cannabinoids were chosen to evaluate their anticancer potential by targeting G6PD. Molecular docking indicated that three molecules, Tetrahydrocannabinolic acid (THCA), Cannabichromenic acid (CBCA), and tetrahydrocannabivarin (THCV), have the highest binding affinities for G6PD of -8.61, - 8.39, and 8.01 Kcal/mol. ADMET analysis found that all of them were safe prospective drug candidates. Molecular dynamics (MD) simulation and MM-PBSA analysis confirm the structural compactness and lower conformational variation of protein-ligand complexes, thereby maintaining structural stability and rigidity. Thus, our in silico investigation exhibited all three cannabinoids as potential competitive inhibitors of G6PD.

Deficiency of betaine-homocysteine methyltransferase activates glucose-6-phosphate dehydrogenase (G6PD) by decreasing arginine methylation of G6PD in hepatocellular carcinogenesis.

Betaine-homocysteine methyltransferase (BHMT) regulates protein methylation and is correlated with tumorigenesis; however, the effects and regulation of BHMT in hepatocarcinogenesis remain largely unexplored. Here, we determined the clinical significance of BHMT in the occurrence and progression of hepatocellular carcinoma (HCC) using tissue samples from 198 patients. BHMT was to be frequently found (86.6%) expressed at relatively low levels in HCC tissues and was positively correlated with the overall survival of patients with HCC. Bhmt overexpression effectively suppressed several malignant phenotypes in hepatoma cells in vitro and in vivo, whereas complete knockout of Bhmt (Bhmt-/-) produced the opposite effect. We combined proteomics, metabolomics, and molecular biological strategies and detected that Bhmt-/- promoted hepatocarcinogenesis and tumor progression by enhancing the activity of glucose-6-phosphate dehydrogenase (G6PD) and PPP metabolism in DEN-induced HCC mouse and subcutaneous tumor-bearing models. In contrast, restoration of Bhmt with an AAV8-Bhmt injection or pharmacological inhibition of G6PD attenuated hepatocarcinogenesis. Additionally, coimmunoprecipitation identified monomethylated modifications of the G6PD, and BHMT regulated the methylation of G6PD. Protein sequence analysis, generation and application of specific antibodies, and site-directed mutagenesis indicated G6PD methylation at the arginine residue 246. Furthermore, we established bidirectionally regulated BHMT cellular models combined with methylation-deficient G6PD mutants to demonstrate that BHMT potentiated arginine methylation of G6PD, thereby inhibiting G6PD activity, which in turn suppressed hepatocarcinogenesis. Taken together, this study reveals a new methylation-regulatory mechanism in hepatocarcinogenesis owing to BHMT deficiency, suggesting a potential therapeutic strategy for HCC treatment.

Abstract 4333: Identification of glucose-6-phosphate dehydrogenase dependency in IDH1 mutant glioma cells using functional genomics

Abstract Astrocytoma and oligodendroglioma are most commonly initiated by missense mutations at the arginine 132 codon of isocitrate dehydrogenase 1 (IDH1). Biochemically the mutant IDH1 protein acquires neomorphic activity: reductive NADPH-dependent catalysis of α-ketoglutarate (αKG) to (R)-2-hydroxyglutarate [(R)-2-HG]. (R)-2-HG interferes with the function of αKG-dependent epigenetic modifiers, resulting in extensive epigenetic remodeling that impairs cellular differentiation and promotes gliomagenesis. Strategies for selectively targeting IDH1-mutant cells offer promise for improved treatment over the standard modalities of surgery, chemotherapy and radiotherapy. Whole-genome CRISPR/Cas9 knockout screens were conducted to identify gene dependencies in isogenic IDH1-mutant and wild-type (WT) U-87 MG cells. Cells were transduced with the Brunello single guide RNA (sgRNA) library, grown for 21 days, then sgRNA distributions were assessed by amplicon sequencing. Gene dependencies were identified using CRISPRcleanR and BAGELR pipelines. We discovered that glucose-6-phosphate dehydrogenase (G6PD), a pentose phosphate pathway (PPP) enzyme, was needed for viability of IDH1-mutant cells, but was dispensable for U-87 MG WT cells. The PPP is the main producer of cytosolic NADPH that is required for de novo lipogenesis, maintenance of antioxidants and production of (R)-2-HG by mutant IDH1. Previous reports demonstrated that IDH1-mutant cells increase PPP flux to support these processes. We have validated this dependency using G6PDi-1, a cell-active inhibitor of G6PD. Growth inhibition (IC50) assays demonstrated that IDH1-mutant U-87 MG cells were threefold more sensitive to G6PDi-1 with IC50 of 23 μM and enhanced cell death (increased propidium iodide uptake), compared with WT U-87 MG cells with IC50 of 67 μM. G6PD knockout was then conducted to further validate this dependency. Nucleofection of IDH1 WT U-87 MG cells with G6PD multi guide RNA-Cas9 ribonucleoproteins resulted in highly efficient knockout of G6PD at day 5 (99-100%), which was maintained at day 21 (96-98%). In contrast, efficient G6PD knockout in IDH1-mutant U-87 MG cells at day 5 (98-100%) was lost following 21 days culture (0-5%), indicating death of almost all edited cells within the culture. Finally, Kaplan-Meier analysis of IDH1-mutant patients in the TCGA lower grade glioma dataset demonstrated that higher G6PD expression correlated with worse median overall survival (7.3 versus 9.5 years; log-rank p=0.01), but was not prognostic in the IDH1 WT TCGA glioblastoma multiforme dataset. These findings demonstrate that a cell line model of IDH1-mutant glioma is highly dependent on G6PD for survival. This observation builds on the recognized importance of the PPP in the metabolic biology of IDH1-mutant malignancy by establishing G6PD as a targetable dependency in this disease. Citation Format: Kim M. Paras, Pooja Patel, Paul Choi, William R. Wilson, Tet-Woo Lee, Stephen M. Jamieson, Dean C. Singleton. Identification of glucose-6-phosphate dehydrogenase dependency in IDH1 mutant glioma cells using functional genomics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4333.

Analysis of the Effects of Pentose Phosphate Pathway Inhibition on the Generation of Reactive Oxygen Species and Epileptiform Activity in Hippocampal Slices.

The pentose phosphate pathway (PPP) is one of three major pathways involved in glucose metabolism, which is regulated by glucose-6-phosphate dehydrogenase (G6PD) controls NADPH formation. NADPH, in turn, regulates the balance of oxidative stress and reactive oxygen species (ROS) levels. G6PD dysfunction, affecting the PPP, is implicated in neurological disorders, including epilepsy. However, PPP's role in epileptogenesis and ROS production during epileptic activity remains unclear. To clarify these points, we conducted electrophysiological and imaging analyses on mouse hippocampal brain slices. Using the specific G6PD inhibitor G6PDi-1, we assessed its effects on mouse hippocampal slices, examining intracellular ROS, glucose/oxygen consumption, the NAD(P)H level and ROS production during synaptic stimulation and in the 4AP epilepsy model. G6PDi-1 increased basal intracellular ROS levels and reduced synaptically induced glucose consumption but had no impact on baselevel of NAD(P)H and ROS production from synaptic stimulation. In the 4AP model, G6PDi-1 did not significantly alter spontaneous seizure frequency or H2O2 release amplitude but increased the frequency and peak amplitude of interictal events. These findings suggest that short-term PPP inhibition has a minimal impact on synaptic circuit activity.

Biochanin A – A G6PD inhibitor: In silico and in vitro studies in non-small cell lung cancer cells (A549)

Secondary metabolites from medicinal plants have a well-established therapeutic potential, with many of these chemicals having specialized medical uses. Isoflavonoids, a type of secondary metabolite, have little cytotoxicity against healthy human cells, making them interesting candidates for cancer treatment. Extensive research has been conducted to investigate the chemo-preventive benefits of flavonoids in treating various cancers. Biochanin A (BA), an isoflavonoid abundant in plants such as red clover, soy, peanuts, and chickpeas, was the subject of our present study. This study aimed to determine how BA affected glucose-6-phosphate dehydrogenase (G6PD) in human lung cancer cells. The study provides meaningful insight and a significant impact of BA on the association between metastasis, inflammation, and G6PD inhibition in A549 cells. Comprehensive in vitro tests revealed that BA has anti-inflammatory effects. Molecular docking experiments shed light on BA's high binding affinity for the G6PD receptor. BA substantially decreased the expression of G6PD and other inflammatory and metastasis-related markers. In conclusion, our findings highlight the potential of BA as a therapeutic agent in cancer treatment, specifically by targeting G6PD and related pathways. BA's varied effects, which range from anti-inflammatory capabilities to metastasis reduction, make it an appealing option for future investigation in the development of new cancer therapeutics.

The Emerging Roles of the Metabolic Regulator G6PD in Human Cancers.

Metabolic reprogramming, especially reprogrammed glucose metabolism, is a well-known cancer hallmark related to various characteristics of tumor cells, including proliferation, survival, metastasis, and drug resistance. Glucose-6-phosphate dehydrogenase (G6PD) is the first and rate-limiting enzyme of the pentose phosphate pathway (PPP), a branch of glycolysis, that converts glucose-6-phosphate (G6P) into 6-phosphogluconolactone (6PGL). Furthermore, PPP produces ribose-5-phosphate (R5P), which provides sugar-phosphate backbones for nucleotide synthesis as well as nicotinamide adenine dinucleotide phosphate (NADPH), an important cellular reductant. Several studies have shown enhanced G6PD expression and PPP flux in various tumor cells, as well as their correlation with tumor progression through cancer hallmark regulation, especially reprogramming cellular metabolism, sustaining proliferative signaling, resisting cell death, and activating invasion and metastasis. Inhibiting G6PD could suppress tumor cell proliferation, promote cell death, reverse chemoresistance, and inhibit metastasis, suggesting the potential of G6PD as a target for anti-tumor therapeutic strategies. Indeed, while challenges-including side effects-still remain, small-molecule G6PD inhibitors showing potential anti-tumor effect either when used alone or in combination with other anti-tumor drugs have been developed. This review provides an overview of the structural significance of G6PD, its role in and regulation of tumor development and progression, and the strategies explored in relation to G6PD-targeted therapy.

Inhibition of non-small cell lung cancer (NSCLC) proliferation through targeting G6PD

Background Mounting evidence has linked cancer metabolic reprogramming with altered redox homeostasis. The pentose phosphate pathway (PPP) is one of the key metabolism-related pathways that has been enhanced to promote cancer growth. The glucose 6-phosphate dehydrogenase (G6PD) of this pathway generates reduced nicotinamide adenine dinucleotide phosphate (NADPH), which is essential for controlling cellular redox homeostasis. Objective This research aimed to investigate the growth-promoting effects of G6PD in non-small cell lung cancer (NSCLC). Methods Clinical characteristics and G6PD expression levels in lung tissues of 64 patients diagnosed with lung cancer at the King Chulalongkorn Memorial Hospital (Bangkok, Thailand) during 2009-2014 were analyzed. G6PD activity in NSCLC cell lines, including NCI-H1975 and NCI-H292, was experimentally inhibited using DHEA and siG6PD to study cancer cell proliferation and migration. Results The positive expression of G6PD in NSCLC tissues was detected by immunohistochemical staining and was found to be associated with squamous cells. G6PD expression levels and activity also coincided with the proliferation rate of NSCLC cell lines. Suppression of G6PD-induced apoptosis in NSCLC cell lines by increasing Bax/Bcl-2 ratio expression. The addition of D-(-)-ribose, which is an end-product of the PPP, increased the survival of G6PD-deficient NSCLC cell lines. Conclusion Collectively, these findings demonstrated that G6PD might play an important role in the carcinogenesis of NSCLC. Inhibition of G6PD might provide a therapeutic strategy for the treatment of NSCLC.

Metabolic classification suggests the GLUT1/ALDOB/G6PD axis as a therapeutic target in chemotherapy-resistant pancreatic cancer

Metabolic reprogramming is known as an emerging mechanism of chemotherapy resistance, but the metabolic signatures of pancreatic ductal adenocarcinomas (PDACs) remain unclear. Here, we characterize the metabolomic profile of PDAC organoids and classify them into glucomet-PDAC (high glucose metabolism levels) and lipomet-PDAC (high lipid metabolism levels). Glucomet-PDACs are more resistant to chemotherapy than lipomet-PDACs, and patients with glucomet-PDAC have a worse prognosis. Integrated analyses reveal that the GLUT1/aldolase B (ALDOB)/glucose-6-phosphate dehydrogenase (G6PD) axis induces chemotherapy resistance by remodeling glucose metabolism in glucomet-PDAC. Increased glycolytic flux, G6PD activity, and pyrimidine biosynthesis are identified in glucomet-PDAC with high GLUT1 and low ALDOB expression, and these phenotypes could be reversed by inhibiting GLUT1 expression or by increasing ALDOB expression. Pharmacological inhibition of GLUT1 or G6PD enhances the chemotherapy response of glucomet-PDAC. Our findings uncover potential metabolic heterogeneity related to differences in chemotherapy sensitivity in PDAC and develop a promising pharmacological strategy for patients with chemotherapy-resistant glucomet-PDAC through the combination of chemotherapy and GLUT1/ALDOB/G6PD axis inhibitors.

MRNA level of antioxidant genes and activity of NADPH-generating enzymes in rotenone-induced parkinsonism in rats

Aim. To analyze the mRNA level of genes encoding antioxidant enzymes and the transcription factors Nrf2 and Foxo1 regulating their expression and the activity of glucose-6-phosphate dehydrogenase (G6PDH) and NADPdependent isocitrate dehydrogenase (NADP-IDH) and assess the correlation between these parameters, oxidative status, and motor coordination parameters in rats with rotenone-induced parkinsonism.Materials and methods. The study was performed on male Wistar rats aged 4–6 months and weighing 200–250 g. Parkinsonism was modeled by subcutaneous administration of rotenone for 10 days at a dose of 2.5 mg / kg. To confirm the development of the pathology, motor coordination tests and histological staining of the cerebral cortex and striatum with hematoxylin and eosin were used. The oxidative status was analyzed based on the levels of conjugated dienes, carbonyl amino acid residues in proteins, and α-tocopherol. The enzyme activity was studied spectrophotometrically by the formation of NADPH. Real-time PCR was used to analyze the level of gene mRNA.Results. During the study, an increase in serum and brain concentrations of conjugated dienes, carbonyl amino acid residues, and α-tocopherol was observed in the experimental group of rats compared to the controls. It could be associated with the redistribution of this compound between tissues during pathology development. The animals with experimental parkinsonism, in addition, were characterized by a decrease in the mRNA level of the Sod1, Gpx1, Gsr, Gsta2, Nfe2l2, and Foxo1 genes, as well as the activity of G6PDH and NADP-IDH. In the rats with experimental parkinsonism, a negative correlation of NADPH-IDH activity in the brain with serum α-tocopherol level and a positive correlation with Gpx1 and Foxo1 mRNA levels in the striatum were found. The level of oxidatively modified proteins in the brain of the animals with PD was negatively correlated with the concentration of Gsta2 mRNA in the striatum, while the specific activity of G6PDH in the serum was characterized by the positive relationship with grip strength.Conclusion. The data obtained indicate that the inhibition of transcription of the genes encoding antioxidant enzymes and regulatory factors Nrf2 and Foxo1 contributed significantly to the development of oxidative stress in PD. A decrease in the activity of G6PDH and NADP-IDH led to a decrease in the availability of NADPH, which is a limiting factor in the functioning of the glutathione antioxidant system. Obviously, the inhibition of G6PDH and NADP-IDH was also an important pathogenic factor in the progression of the pathology. Along with a decrease in the content of antioxidant gene mRNA in the brain tissues, the level of α-tocopherol increased in the rats with parkinsonism, which could be the result of an imbalance in the functioning of antioxidant system.

G6PDi-1 is a Potent Inhibitor of G6PDH and of Pentose Phosphate pathway-dependent Metabolic Processes in Cultured Primary Astrocytes

Glucose-6-phosphate dehydrogenase (G6PDH) catalyses the rate limiting first step of the oxidative part of the pentose phosphate pathway (PPP), which has a crucial function in providing NADPH for antioxidative defence and reductive biosyntheses. To explore the potential of the new G6PDH inhibitor G6PDi-1 to affect astrocytic metabolism, we investigated the consequences of an application of G6PDi-1 to cultured primary rat astrocytes. G6PDi-1 efficiently inhibited G6PDH activity in lysates of astrocyte cultures. Half-maximal inhibition was observed for 100 nM G6PDi-1, while presence of almost 10 µM of the frequently used G6PDH inhibitor dehydroepiandrosterone was needed to inhibit G6PDH in cell lysates by 50%. Application of G6PDi-1 in concentrations of up to 100 µM to astrocytes in culture for up to 6 h did not affect cell viability nor cellular glucose consumption, lactate production, basal glutathione (GSH) export or the high basal cellular ratio of GSH to glutathione disulfide (GSSG). In contrast, G6PDi-1 drastically affected astrocytic pathways that depend on the PPP-mediated supply of NADPH, such as the NAD(P)H quinone oxidoreductase (NQO1)-mediated WST1 reduction and the glutathione reductase-mediated regeneration of GSH from GSSG. These metabolic pathways were lowered by G6PDi-1 in a concentration-dependent manner in viable astrocytes with half-maximal effects observed for concentrations between 3 and 6 µM. The data presented demonstrate that G6PDi-1 efficiently inhibits the activity of astrocytic G6PDH and impairs specifically those metabolic processes that depend on the PPP-mediated regeneration of NADPH in cultured astrocytes.

Pan-cancer analysis of G6PD carcinogenesis in human tumors.

Glucose-6-phosphate dehydrogenase (G6PD) is involved in the catalytic pentose phosphate pathway (PPP), which is closely related to energy metabolism. G6PD plays a crucial role in many types of cancer, but the specific molecular mechanisms of G6PD in cancer remain unclear. Therefore, we investigated the potential oncogenic role of G6PD in various tumors based on The Cancer Genome Atlas (TCGA), the cBioPortal datasets, the University of California Santa Cruz (UCSC) Xena browser and the UALCAN-based online tool. G6PD was highly expressed in several cancer tissues (hepatocellular carcinoma, glioma, and breast cancer) compared with normal tissues and was significantly associated with poor prognosis of hepatocellular carcinoma, clear cell renal cell carcinoma, and breast cancer. Promoter methylation levels of G6PD were lower in Bladder Urothelial Carcinoma (BLCA) (P = 2.77e-02), breast invasive carcinoma (BRCA) (P = 1.62e-12), kidney renal clear cell carcinoma (KIRC) (P = 4.23e-02), kidney renal papillary cell carcinoma (KIRP) (P = 2.64e-03), liver hepatocellular carcinoma (LIHC) (P = 1.76e-02), stomach adenocarcinoma (STAD) (P = 3.50e-02), and testicular germ cell tumors (TGCT) (P = 1.62e-12) and higher in prostate adenocarcinoma (PRAD) (P = 1.81e-09) and uterine corpus endometrial carcinoma (UCEC) (P = 2.96e-04) compared with corresponding normal tissue samples. G6PD expression was positively correlated with the infiltration level of immune cells in most tumors, suggesting that G6PD may be involved in tumor immune infiltration. In addition, the functional mechanism of G6PD also involves "Carbon metabolism", "Glycolysis/Gluconeogenesis", "Pentose phosphate pathway", and "Central carbon pathway metabolism in cancer signaling pathway". This pan-cancer study provides a relatively broad understanding of the oncogenic role of G6PD in various tumors and presents a theoretical basis for the development of G6PD inhibitors as therapeutic drugs for multiple cancers.

G6PD activation in TNBC cells induces macrophage recruitment and M2 polarization to promote tumor progression.

Glucose-6-phosphate dehydrogenase (G6PD) is involved in triple-negative breast cancer (TNBC) progression. Metabolic crosstalk between cancer cells and tumor-associated macrophages mediates tumor progression in TNBC. Molecular biological methods were applied to clarify the mechanism of the crosstalk between TNBC cells and M2 macrophages. In the present study, we verified that G6PD overexpression drives M2 macrophage polarization by directly combining with phospho-STAT1 and upregulating CCL2 and TGF-β1 secretion in TNBC cells. In turn, M2-like TAMs activated TNBC cells through IL-10 secretion, providing feedback to upregulate G6PD and promote TNBC cell migration and proliferation in vitro. Furthermore, we found that 6-AN (a specific inhibitor of G6PD) not only suppressed the cancer-driven polarization of macrophages toward the M2 phenotype but also inhibited the inherent M2 polarization of macrophages. Targeting the G6PD-regulated pentose phosphate pathway restrained TNBC progression and M2-type polarization of macrophages in vitro and in vivo.

Metformin attenuates sevoflurane-induced neurogenesis damage and cognitive impairment: involvement of the Nrf2/G6PD pathway.

Anesthetics such as sevoflurane are commonly administered to infants and children. However, the possible neurotoxicity caused by prolonged or repetitive exposure to it should be a concern. The neuroprotective effects of metformin are observed in many models of neurological disorders. In this study, we investigated whether metformin could reduce the developmental neurotoxicity induced by sevoflurane exposure in neonatal rats and the potential mechanism. Postnatal day 7 (PND 7) Sprague-Dawley rats and neural stem cells (NSCs) were treated with normal saline or metformin before sevoflurane exposure. The Morris water maze (MWM) was used to observe spatial memory and learning at PND 35-42. Immunofluorescence staining was used to detect neurogenesis in the subventricular zone (SVZ) of the lateral ventricle and the subgranular zone (SGZ) of the dentate gyrus at PND 14. MTT assays, immunofluorescence staining, and TUNEL staining were used to assess the viability, proliferation, differentiation, and apoptosis of NSCs. Western blotting and ELISA were used to assess the protein expression of cleaved caspase-3, nuclear factor erythroid 2-related factor 2 (Nrf2), and glucose-6-phosphate dehydrogenase (G6PD) pathway-related molecules. Exposure to sevoflurane resulted in late cognitive defects, impaired neurogenesis in both the SVZ and SGZ, reduced NSC viability and proliferation, increased NSC apoptosis, and decreased protein expression of G6PD in vitro. Metformin pretreatment attenuated sevoflurane-induced cognitive functional decline and neurogenesis inhibition. Metformin pretreatment also increased the protein expression of Nrf2 and G6PD. However, treatment with the Nrf2 inhibitor, ML385 or the G6PD inhibitor, dehydroepiandrosterone (DHEA) reversed the protective effect of metformin on sevoflurane-induced NSC damage in vitro. Our findings suggested that metformin could reduce sevoflurane-induced neurogenesis damage and neurocognitive defects in the developing rat brain by influencing the Nrf2/G6PD signaling pathways.

Glutamine promotes O-GlcNAcylation of G6PD and inhibits AGR2 S-glutathionylation to maintain the intestinal mucus barrier in burned septic mice

Mucus forms the first line of defence of the intestinal mucosa barrier, and mucin is its core component. Glutamine is a vital energy substance for goblet cells; it can promote mucus synthesis and alleviate damage to the intestinal mucus barrier after burn injury, but its mechanism is not fully understood. This study focused on the molecular mechanisms underlying the effects of glutamine on the synthesis and modification of mucin 2 (MUC2) by using animal and cellular models of burn sepsis. We found that anterior gradient-2 (AGR2) plays a key role in the posttranslational modification of MUC2. Oxidative stress induced by burn sepsis enhanced the S-glutathionylation of AGR2, interfered with the processing and modification of MUC2 precursors by AGR2 and blocked the synthesis of mature MUC2. Further studies revealed that NADPH, catalysed by glucose-6-phosphate dehydrogenase (G6PD), is a key molecule in inhibiting oxidative stress and regulating AGR2 activity. Glutamine promotes O-linked N-acetylglucosamine (O-GlcNAc) modification of G6PD via the hexosamine pathway, which facilitates G6PD homodimer formation and increases NADPH synthesis, thereby inhibiting AGR2 S-glutathionylation and promoting MUC2 maturation, ultimately reducing damage to the intestinal mucus barrier after burn sepsis. Overall, we have demonstrated that the central mechanisms of glutamine in promoting MUC2 maturation and maintaining the intestinal mucus barrier are the enhancement of G6PD glycosylation and inhibition of AGR2 S-glutathionylation.

Dual inhibition of CPT1A and G6PD suppresses glioblastoma tumorspheres.

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). 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. 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. 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.

New Inhibitors of Glucose-6-Phosphate Dehydrogenase Discovered by Molecular Docking

The aim of this study is to in silico screen new glucose-6-phosphate dehydrogenase (G6PD) inhibitors. glucose-6-phosphate dehydrogenase is the first and regulator of pentose phosphate pathway providing NADPH and ribose-5-phosphate required for various syntheses from fatty acids to DNA. G6PD is linked to oxidative stress and hence, to inflammation as well. Therefore, G6PD inhibition is a useful target against inflammation, cancer and some infections. Virtual screening of 15 ligands in the NADP-binding site in comparison with the standard inhibitor 6-aminonicotinamide using iGEMDOCK. Besides, ADME properties of the selected compounds were performed via SWISSADME webserver. All the tested ligands were better than reference inhibitor in terms of binding energy as well as pharmacokinetic and ADME parameters. Moreover, of all tested compounds, ligand 15 showed best docking fitness (-115 Kcal/mole total energy). Novel compounds were screened to be lead inhibitors of G6PD enzyme and ligand 15 ranked first.

Plastidic G6PDH and root structure regulation are essential for high nitrogen use efficiency in highland barley adaptation to low nitrogen

Nitrogen (N) use efficiency (NUE) is a major factor determining crop growth and productivity. It is closely related to N acquisition and assimilation efficiency. In this study, the respective responses and mechanisms of highland barley (Kunlun14) and barley (Ganpi6) were investigated under low N condition. The root length, plant height, root/shoot ratio, and relative root growth rate in Kunlun14 were greater than those in Ganpi6 under low N stress, suggesting Kunlun14 has stronger tolerance to low N. The contents of nitrate and amino acids were decreased more in Ganpi6 than in Kunlun14 under low N stress. Moreover, Kunlun14 maintained higher nitrate uptake, translocation and assimilation capacity than Ganpi6. Glucose-6-phosphate dehydrogenase (G6PDH) activity, especially the plastidic G6PDH (Pla-G6PDH) activity, was markedly induced by low N in Kunlun14. Glucosamine, a G6PDH inhibitor, reduced nitrate uptake and assimilation capacity under low N stress. qRT-PCR and RNA-Seq analysis showed that the expression of HvG6PDH3 , encoding Pla-G6PDH3, was markedly induced by low N in barley roots. In addition, the differentially expressed genes in barley roots involved in hormones, transcription factors and cell wall biosynthesis play key roles under low N by regulating root development and N metabolism. Overexpression of HvG6PDH3 in Arabidopsis up-regulated the expression of AtNRT1.5 and AtNRT2.1 and increased the nitrate uptake and translocation capacity, which resulted in higher seed yield in HvG6PDH3 -overexpressors under low N stress. Taken together, HvG6PDH3 and the genes involved in regulating root architecture play essential roles in Kunlun14 tolerance to low N, which is conductive to maintaining high N uptake and assimilation efficiency. • Highland barley (Kunlun14) has higher NUE than barley (Ganpi6) under low N stress. • HvG6PDH3 is involved in the tolerance of highland barley to low N by positively regulating N uptake and assimilation. • DEGs involved in plant hormones, transcription factors and cell wall biosynthesis play key roles under low N stress.

Adaptations of key metabolic pathways in primary and metastatic epithelial ovarian cancer (253)

Objectives: Patients with ovarian cancer (OC) often present with advanced-stage disease at diagnosis; however, the molecular mechanisms which drive the aggressive nature of OC metastases have not been well characterized. Metastasizing cancer cells undergo metabolic reprogramming to utilize available lipids in the metastatic niche of the omentum. This study aimed to understand the compensatory metabolic mechanisms that enable this OC metastasis. Our work focused on understanding the contributions of the pentose phosphate pathway (PPP)—a key mechanism responsible for redox homeostasis—in enabling this evolution. Methods: Using gene expression data of matched human primary and omental tumor samples (n=30), we performed targeted analysis of metabolic gene expression changes, which revealed upregulation of the PPP in omental metastases. We then performed in vitro and in vivo experiments using pre-clinical ovarian cancer models (SKOV3, IGROV, HEYA8). Given the canonical role of the PPP in maintaining redox homeostasis, we assessed oxidative stress in organoid cultures from omental metastases harvested at mouse necropsy and in cultures grown in omental conditioned media. Inhibition of the rate-limiting enzyme of the PPP, glucose-6-phosphate dehydrogenase (G6PD), was performed via shRNA knockdowns and treated with a pharmacological inhibitor. HeyA8 tumor-bearing mice were treated with the G6PD inhibitor, and the metastatic burden was evaluated using IVIS during treatment and in peritoneal organs following the sacrifice. Statistical significance was established using unpaired two-tailed Student’s t-tests. Results: Differential analysis of metabolic gene expression and pathway analysis revealed upregulation of the PPP in omental metastases compared to primary ovarian tumors (p<0.05, EnrichR Score = 800). Primary tumors and omental metastases were harvested from SKOV3, HeyA8, and IGROV1 tumor-bearing mice at necropsy and used to establish organoids. DCFH-DA, a fluorogenic probe for ROS, measured higher levels of oxidative stress in metastatic organoids than primary tumors (normalized F525= 11.3623, p<0.0005). SKOV3 organoids expressing HyPer, a ratiometric biosensor of intracellular H2O2, exhibited higher oxidative stress when grown in omental conditioned media versus basal organoid media (normalized F420/F500=1.27, p<0.05). Pharmacological and shRNA inhibition of G6PD sensitized cells to oxidative stress, reducing cell viability in vitro (p<0.05). Treatment with a G6PD inhibitor in vivo significantly decreased tumor growth and metastases compared to vehicle treatment (p<0.005). Objectives: Patients with ovarian cancer (OC) often present with advanced-stage disease at diagnosis; however, the molecular mechanisms which drive the aggressive nature of OC metastases have not been well characterized. Metastasizing cancer cells undergo metabolic reprogramming to utilize available lipids in the metastatic niche of the omentum. This study aimed to understand the compensatory metabolic mechanisms that enable this OC metastasis. Our work focused on understanding the contributions of the pentose phosphate pathway (PPP)—a key mechanism responsible for redox homeostasis—in enabling this evolution. Methods: Using gene expression data of matched human primary and omental tumor samples (n=30), we performed targeted analysis of metabolic gene expression changes, which revealed upregulation of the PPP in omental metastases. We then performed in vitro and in vivo experiments using pre-clinical ovarian cancer models (SKOV3, IGROV, HEYA8). Given the canonical role of the PPP in maintaining redox homeostasis, we assessed oxidative stress in organoid cultures from omental metastases harvested at mouse necropsy and in cultures grown in omental conditioned media. Inhibition of the rate-limiting enzyme of the PPP, glucose-6-phosphate dehydrogenase (G6PD), was performed via shRNA knockdowns and treated with a pharmacological inhibitor. HeyA8 tumor-bearing mice were treated with the G6PD inhibitor, and the metastatic burden was evaluated using IVIS during treatment and in peritoneal organs following the sacrifice. Statistical significance was established using unpaired two-tailed Student’s t-tests. Results: Differential analysis of metabolic gene expression and pathway analysis revealed upregulation of the PPP in omental metastases compared to primary ovarian tumors (p<0.05, EnrichR Score = 800). Primary tumors and omental metastases were harvested from SKOV3, HeyA8, and IGROV1 tumor-bearing mice at necropsy and used to establish organoids. DCFH-DA, a fluorogenic probe for ROS, measured higher levels of oxidative stress in metastatic organoids than primary tumors (normalized F525= 11.3623, p<0.0005). SKOV3 organoids expressing HyPer, a ratiometric biosensor of intracellular H2O2, exhibited higher oxidative stress when grown in omental conditioned media versus basal organoid media (normalized F420/F500=1.27, p<0.05). Pharmacological and shRNA inhibition of G6PD sensitized cells to oxidative stress, reducing cell viability in vitro (p<0.05). Treatment with a G6PD inhibitor in vivo significantly decreased tumor growth and metastases compared to vehicle treatment (p<0.005).

Smilax china root extract as a novel Glucose- 6-phosphate dehydrogenase inhibitor for the treatment of hepatocellular carcinoma

A novel therapeutic strategy for cancer treatment is to target altered tumor metabolism. Glucose- 6-phosphate dehydrogenase (G6PD) has been recently discovered to be implicated in apoptosis and angiogenesis, making it an excellent target in cancer treatment. The current study aimed to screen the plant extracts library to find potent hits against G6PD through enzymatic assay. Protein expression was induced by IPTG and purified using Ni-NTA columns after transformation of the pET-24a-HmG6PD plasmid into E. coli BL21-DE3 strain. An enzymatic assay was established by using purified rG6PD protein, for the screening of G6PD inhibitors. Out of 46 plant extracts screened, the sixteen plant extracts have shown inhibitory activity against the G6PD enzyme. At doses from 1 to 4 µg/ml, this extract demonstrated concentration-dependent inhibition of G6PD with an IC50 value of I.397 µg/ml. Moreover, the anticancer activity evaluation against HepG2 cells determined Smilax china as a potent inhibitor of cancer cells (IC50 value of 16.017 μg/ml). The acute and subacute toxicities were not observed in mice with various concentrations (50, 100, 200 and 2000 mg/kg). Furthermore, to identify the compounds from Smilax china as G6PD inhibitors, a literature-based phytochemical investigation of Smilax china was conducted, and sixty compounds were docked against the NADP+ and G6P binding sites of G6PD. The results of this study showed that three compounds were Scirpusin A, Smilachinin and Daucosterol with MolDock Score of −156.832, −148.215, and −145.733 respectively, against NADP+ binding site of G6PD. Conclusively, Smilax china root extract could be a safer drug candidate for the treatment of hepatocellular carcinoma.

G6PD inhibition sensitizes ovarian cancer cells to oxidative stress in the metastatic omental microenvironment.

SUMMARYOvarian cancer (OC) is the most lethal gynecological malignancy, with aggressive metastatic disease responsible for the majority of OC-related deaths. In particular, OC tumors preferentially metastasize to and proliferate rapidly in the omentum. Here, we show that metastatic OC cells experience increased oxidative stress in the omental microenvironment. Metabolic reprogramming, including upregulation of the pentose phosphate pathway (PPP), a key cellular redox homeostasis mechanism, allows OC cells to compensate for this challenge. Inhibition of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the PPP, reduces tumor burden in pre-clinical models of OC, suggesting that this adaptive metabolic dependency is important for OC omental metastasis.