bims-glucam 2021-11-28 papers

bims-glucam

Biomed News

on Glutamine cancer metabolism

Issue of 2021–11–28
sixteen papers selected by
Sreeparna Banerjee, Middle East Technical University

Circ-CREBBP promotes cell tumroigenesis and glutamine catabolism in glioma by regulating miR-375/glutaminase axis.
Glutamine deficiency induces lipolysis in adipocytes.
Succinate receptor 1 inhibits mitochondrial respiration in cancer cells addicted to glutamine.
Circ_0000463 contributes to the progression and glutamine metabolism of non-small-cell lung cancer by targeting miR-924/SLC1A5 signaling.
Immunosuppression Induced by Glutamine Deprivation Occurs via Activating PD-L1 Transcription in Bladder Cancer.
Metabolic stress induces GD2+ cancer stem cell-like phenotype in triple-negative breast cancer.
Mitochondria-Mediated Apoptosis of HCC Cells Triggered by Knockdown of Glutamate Dehydrogenase 1: Perspective for Its Inhibition through Quercetin and Permethylated Anigopreissin A.
Metabonomics study of the effects of single copy mutant KRAS in the presence or absence of WT allele using human HCT116 isogenic cell lines.
Glutamine Homeostasis and Its Role in the Adaptive Strategies of the Blind Mole Rat, Spalax.
HIF1 and ID1 Interplay Confers Adaptive Survival to HIF1α-Inhibition.
An Asp to Strike Out Cancer? Therapeutic Possibilities Arising from Aspartate's Emerging Roles in Cell Proliferation and Survival.
Cancer Stem Cells: Metabolic Characterization for Targeted Cancer Therapy.
Discovery of GOT1 Inhibitors from a Marine-Derived Aspergillus terreus That Act against Pancreatic Ductal Adenocarcinoma.
Glyceraldehyde-3-phosphate dehydrogenase and glutamine synthetase inhibition in the presence of pro-inflammatory cytokines contribute to the metabolic imbalance of diabetic retinopathy.
Discovery of metabolomic biomarkers for discriminating platinum-sensitive and platinum-resistant ovarian cancer by using GC-MS.
Glucose metabolism and pyruvate carboxylase enhance glutathione synthesis and restrict oxidative stress in pancreatic islets.

Brain Res. 2021 Nov 20. pii: S0006-8993(21)00589-8. [Epub ahead of print] 147730

Circ-CREBBP promotes cell tumroigenesis and glutamine catabolism in glioma by regulating miR-375/glutaminase axis.

Lintao Zhang, Lin Ye, Zengliang Xu, Yanfei Jin, Dewen Song.

  Circular RNA CREB-binding protein (circ-CREBBP) has been reported to involve in the tumorigenesis of glioma. However, the role and underlying molecular mechanism of circ-CREBBP in glioma glutamine catabolism remain unclear. The expression of circ-CREBBP, microRNA (miR)-375 and glutaminase (GLS) was detected using quantitative real-time polymerase chain reaction and western blot. The 3‑(4, 5‑dimethylthiazol‑2‑y1)‑2, 5‑diphenyl tetrazolium bromide (MTT), colony formation, flow cytometry and transwell assays were used to determine the effects of them on glioma cell malignant biological behaviors in vitro. Glutamine metabolism was analyzed using assay kits. Murine xenograft model was established to investigate the role of circ-CREBBP in vivo. The binding interactions between miR-375 and circ-CREBBP or GLS were confirmed by the dual-luciferase reporter assay. Circ-CREBBP was highly expressed in glioma tissues and cells, and high expression of circ-CREBBP predicted poor prognosis. Circ-CREBBP knockdown suppressed cell proliferation, migration, invasion and glutamine metabolism while expedited cell apoptosis in glioma in vitro, as well as impeded tumor growth in vivo. Circ-CREBBP directly targeted miR-375, which was demonstrated to restrain glioma cell growth, motility and glutamine metabolism. Moreover, miR-375 inhibition reverted the anticancer effects of circ-CREBBP knockdown on glioma cells. GLS was a target of miR-375, GLS silencing or the treatment of GLS inhibitor bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide (BPTES) impaired glioma cell malignant phenotypes and glutamine metabolism. Importantly, GLS up-regulation weakened the tumor-suppressive functions of miR-375 on glioma cells. Mechanistically, circ-CREBBP indirectly regulated GLS expression through sponging miR-375. In all, circ-CREBBP expedited glioma tumorigenesis and glutamine metabolism through miR-375/GLS axis, suggesting a promising target for combined glioma therapy.

Keywords:  circ-CREBBP; glioma; glutaminase; glutamine catabolism; miR-375

DOI:  https://doi.org/10.1016/j.brainres.2021.147730
Biochem Biophys Res Commun. 2021 Nov 13. pii: S0006-291X(21)01554-0. [Epub ahead of print]585 155-161

Glutamine deficiency induces lipolysis in adipocytes.

Kenta Okuro, Atsunori Fukuhara, Tomomi Minemura, Tomoaki Hayakawa, Shigeki Nishitani, Yosuke Okuno, Michio Otsuki, Iichiro Shimomura.

  Glutamine is the most abundant amino acid in the body, and adipose tissue is one of the glutamine-producing organs. Glutamine has important and unique metabolic functions; however, its effects in adipocytes are still unclear. 3T3-L1 adipocytes produced and secreted glutamine dependent on glutamine synthetase, but preadipocytes did not. The inhibition of glutamine synthetase by l-methionine sulfoximine (MSO) impaired the differentiation of preadipocytes to mature adipocytes, and this inhibitory effect of MSO was rescued by exogenous glutamine supplementation. Glutamine concentrations were low, and Atgl gene expression was high in epididymal white adipose tissues of fasting mice in vivo. In 3T3-L1 adipocytes, glutamine deprivation induced Atgl expression and increased glycerol concentration in culture medium. Atgl expression is regulated by FoxO1, and glutamine deprivation reduced FoxO1 phosphorylation (Ser256), indicating the activation of FoxO1. These results demonstrate that glutamine is necessary for the differentiation of preadipocytes and regulates lipolysis through FoxO1 in mature adipocytes.

Keywords:  Adipocyte; Atgl; FoxO1; Glutamine; Lipolysis

DOI:  https://doi.org/10.1016/j.bbrc.2021.11.043
Cancer Lett. 2021 Nov 20. pii: S0304-3835(21)00591-7. [Epub ahead of print]

Succinate receptor 1 inhibits mitochondrial respiration in cancer cells addicted to glutamine.

Philipp Rabe, Aenne-Dorothea Liebing, Petra Krumbholz, Robert Kraft, Claudia Stäubert.

  Cancer cells display metabolic alterations to meet the bioenergetic demands for their high proliferation rates. Succinate is a central metabolite of the tricarboxylic acid (TCA) cycle, but was also shown to act as an oncometabolite and to specifically activate the succinate receptor 1 (SUCNR1), which is expressed in several types of cancer. However, functional studies focusing on the connection between SUCNR1 and cancer cell metabolism are still lacking. In the present study, we analyzed the role of SUCNR1 for cancer cell metabolism and survival applying different signal transduction, metabolic and imaging analyses. We chose a gastric, a lung and a pancreatic cancer cell line for which our data revealed functional expression of SUCNR1. Further, presence of glutamine (Gln) caused high respiratory rates and elevated expression of SUCNR1. Knockdown of SUCNR1 resulted in a significant increase of mitochondrial respiration and superoxide production accompanied by an increase in TCA cycle throughput and a reduction of cancer cell survival in the analyzed cancer cell lines. Combination of SUCNR1 knockdown and treatment with the chemotherapeutics cisplatin and gemcitabine further increased cancer cell death. In summary, our data implicates that SUCNR1 is crucial for Gln-addicted cancer cells by limiting TCA cycle throughput, mitochondrial respiration and the production of reactive oxygen species, highlighting its potential as a pharmacological target for cancer treatment.

Keywords:  Cancer metabolism; GPR91; Glutaminolysis; Metabolite-sensing GPCR; SUCNR1

DOI:  https://doi.org/10.1016/j.canlet.2021.11.024
J Clin Lab Anal. 2021 Nov 22. e24116

Circ_0000463 contributes to the progression and glutamine metabolism of non-small-cell lung cancer by targeting miR-924/SLC1A5 signaling.

Yunzhong Liu, Shujun Wang, Songli Pan, Qingfeng Yan, Yueping Li, Ying Zhao.

   BACKGROUND: Circular RNAs (circRNAs) have shown pivotal regulatory roles in the pathology of non-small cell lung cancer (NSCLC). However, the role of circ_0000463 in NSCLC progression and its associated molecular mechanism remain to be illustrated.
METHODS: Cell proliferation ability was analyzed by colony formation assay and 5-ethynyl-2'-deoxyuridine (EdU) assay. Cell migration and invasion abilities were assessed by scratch test and transwell invasion assay. Flow cytometry was employed to analyze cell apoptotic rate. The interaction between microRNA-924 (miR-924) and circ_0000463 or solute carrier family 1 member 5 (SLC1A5) was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. The uptake of glutamine and the production of glutamate and α-ketoglutarate were analyzed using their corresponding kits. Xenograft model in vivo was established to analyze the role of circ_0000463 in tumor growth.
RESULTS: Circ_0000463 expression was elevated in NSCLC tissues and cell lines. Circ_0000463 knockdown suppressed the proliferation, migration, and invasion and promoted the apoptosis of NSCLC cells. Circ_0000463 acted as a molecular sponge for miR-924, and circ_0000463 interference-mediated anti-tumor effects were largely reversed by the silence of miR-924 in NSCLC cells. miR-924 interacted with the 3' untranslated region (3'UTR) of SLC1A5, and SLC1A5 overexpression largely overturned miR-924 overexpression-mediated anti-tumor effects in NSCLC cells. Moreover, circ_0000463 absence suppressed the glutamine metabolism of NSCLC cells by targeting miR-924/SLC1A5 axis. Circ_0000463 knockdown suppressed xenograft tumor growth in vivo.
CONCLUSION: Circ_0000463 absence suppressed the malignant behaviors and glutamine metabolism of NSCLC cells through mediating miR-924/SLC1A5 axis.

Keywords:  SLC1A5; circ_0000463; glutamine metabolism; miR-924; non-small-cell lung cancer

DOI:  https://doi.org/10.1002/jcla.24116
Front Mol Biosci. 2021 ;8 687305

Immunosuppression Induced by Glutamine Deprivation Occurs via Activating PD-L1 Transcription in Bladder Cancer.

Liping Wang, Ting Xu, Xuecheng Yang, Zhijuan Liang, Jisheng Zhang, Dan Li, Yuanbin Chen, Guofeng Ma, Yonghua Wang, Ye Liang, Haitao Niu.

  Few studies have reported whether nutrients in the tumor microenvironment can regulate the expression of PD-L1. Since tumor cells are often situated in a low-glutamine environment, we investigated PD-L1 expression under glutamine deprivation in bladder cancer cells. PD-L1 expression and the activation of the EGFR/MEK/ERK/c-Jun signaling pathway under glutamine deprivation were investigated by qPCR, Western blot, and immunofluorescence analyses. C-Jun-mediated transcriptional regulation of the PD-L1 gene was assessed by ChIP. PD-L1 expression and activation of the EGFR/MEK/ERK/c-Jun signaling pathway were assessed in T24 cells, TCCSUP cells and BALB/c mice with or without glutamine supplementation. Additionally, the impact of PD-L1 expression under glutamine deprivation on the function of T cells was investigated by ELISA. The expression of PD-L1 and EGFR/MEK/ERK/c-Jun pathway activation were elevated by glutamine deprivation, and c-Jun was enriched in the enhancer region of PD-L1. The expression of PD-L1 was considerably impaired by inhibiting the EGFR/MEK/ERK/c-Jun pathway and was elevated by activating this signaling pathway. In addition, the elevated PD-L1 expression and MEK/ERK/c-Jun signaling pathway activation were reduced by glutamine supplementation in vitro and in vivo. PD-L1 upregulation by glutamine deprivation in bladder cancer cells could reduce IFN-γ production by T cells. The expression of PD-L1 was upregulated under glutamine deprivation through the EGFR/MEK/ERK/c-Jun pathway to impair T cell function.

Keywords:  MEK/ERK/c-Jun signaling pathway; PD-L1; T cells; bladder cancer; glutamine deprivation

DOI:  https://doi.org/10.3389/fmolb.2021.687305
Br J Cancer. 2021 Nov 22.

Metabolic stress induces GD2+ cancer stem cell-like phenotype in triple-negative breast cancer.

Appalaraju Jaggupilli, Stanley Ly, Khoa Nguyen, Vivek Anand, Bin Yuan, Fouad El-Dana, Yuanqing Yan, Zoe Arvanitis, Danthasinghe Waduge Badrajee Piyarathna, Nagireddy Putluri, Helen Piwnica-Worms, Henry Charles Manning, Michael Andreeff, V Lokesh Battula.

BACKGROUND: Metabolic stress resulting from nutrient deficiency is one of the hallmarks of a growing tumour. Here, we tested the hypothesis that metabolic stress induces breast cancer stem-like cell (BCSC) phenotype in triple-negative breast cancer (TNBC).
METHODS: Flow cytometry for GD2 expression, mass spectrometry and Ingenuity Pathway Analysis for metabolomics, bioinformatics, in vitro tumorigenesis and in vivo models were used.
RESULTS: Serum/glucose deprivation not only increased stress markers but also enhanced GD2+ BCSC phenotype and function in TNBC cells. Global metabolomics profiling identified upregulation of glutathione biosynthesis in GD2high cells, suggesting a role of glutamine in the BCSC phenotype. Cueing from the upregulation of the glutamine transporters in primary breast tumours, inhibition of glutamine uptake using small-molecule inhibitor V9302 reduced GD2+ cells by 70-80% and BCSC characteristics in TNBC cells. Mechanistic studies revealed inhibition of the mTOR pathway and induction of ferroptosis by V9302 in TNBC cells. Finally, inhibition of glutamine uptake significantly reduced in vivo tumour growth in a TNBC patient-derived xenograft model using NSG (non-obese diabetic/severe combined immunodeficiency with a complete null allele of the IL-2 receptor common gamma chain) mice.
CONCLUSION: Here, we show metabolic stress results in GD2+ BCSC phenotype in TNBC and glutamine contributes to GD2+ phenotype, and targeting the glutamine transporters could complement conventional chemotherapy in TNBC.

DOI: https://doi.org/10.1038/s41416-021-01636-y
Biomedicines. 2021 Nov 11. pii: 1664. [Epub ahead of print]9(11):

Mitochondria-Mediated Apoptosis of HCC Cells Triggered by Knockdown of Glutamate Dehydrogenase 1: Perspective for Its Inhibition through Quercetin and Permethylated Anigopreissin A.

Michela Marsico, Anna Santarsiero, Ilaria Pappalardo, Paolo Convertini, Lucia Chiummiento, Alessandra Sardone, Maria Antonietta Di Noia, Vittoria Infantino, Simona Todisco.

  Metabolic reprogramming is a hallmark of cancer cells required to ensure high energy needs and the maintenance of redox balance. A relevant metabolic change of cancer cell bioenergetics is the increase in glutamine metabolism. Hepatocellular carcinoma (HCC), one of the most lethal cancer and which requires the continuous development of new therapeutic strategies, shows an up-regulation of human glutamate dehydrogenase 1 (hGDH1). GDH1 function may be relevant in cancer cells (or HCC) to drive the glutamine catabolism from L-glutamate towards the synthesis of α-ketoglutarate (α-KG), thus supplying key tricarboxylic acid cycle (TCA cycle) metabolites. Here, the effects of hGLUD1 gene silencing (siGLUD1) and GDH1 inhibition were evaluated. Our results demonstrate that siGLUD1 in HepG2 cells induces a significant reduction in cell proliferation (58.8% ± 10.63%), a decrease in BCL2 expression levels, mitochondrial mass (75% ± 5.89%), mitochondrial membrane potential (30% ± 7.06%), and a significant increase in mitochondrial superoxide anion (25% ± 6.55%) compared to control/untreated cells. The inhibition strategy leads us to identify two possible inhibitors of hGDH1: quercetin and Permethylated Anigopreissin A (PAA). These findings suggest that hGDH1 could be a potential candidate target to impair the metabolic reprogramming of HCC cells.

Keywords:  GLUD1; HCC; Permethylated Anigopreissin A (PAA); apoptosis; hGDH1; inhibition; mitochondrial mass; quercetin; redox homeostasis

DOI:  https://doi.org/10.3390/biomedicines9111664
Metabolomics. 2021 Nov 25. 17(12): 104

Metabonomics study of the effects of single copy mutant KRAS in the presence or absence of WT allele using human HCT116 isogenic cell lines.

Dorna Varshavi, Dorsa Varshavi, Nicola McCarthy, Kirill Veselkov, Hector C Keun, Jeremy R Everett.

   INTRODUCTION: KRAS was one of the earliest human oncogenes to be described and is one of the most commonly mutated genes in different human cancers, including colorectal cancer. Despite KRAS mutants being known driver mutations, KRAS has proved difficult to target therapeutically, necessitating a comprehensive understanding of the molecular mechanisms underlying KRAS-driven cellular transformation.
OBJECTIVES: To investigate the metabolic signatures associated with single copy mutant KRAS in isogenic human colorectal cancer cells and to determine what metabolic pathways are affected.
METHODS: Using NMR-based metabonomics, we compared wildtype (WT)-KRAS and mutant KRAS effects on cancer cell metabolism using metabolic profiling of the parental KRAS G13D/+ HCT116 cell line and its isogenic, derivative cell lines KRAS +/- and KRAS G13D/-.
RESULTS: Mutation in the KRAS oncogene leads to a general metabolic remodelling to sustain growth and counter stress, including alterations in the metabolism of amino acids and enhanced glutathione biosynthesis. Additionally, we show that KRASG13D/+ and KRASG13D/- cells have a distinct metabolic profile characterized by dysregulation of TCA cycle, up-regulation of glycolysis and glutathione metabolism pathway as well as increased glutamine uptake and acetate utilization.
CONCLUSIONS: Our study showed the effect of a single point mutation in one KRAS allele and KRAS allele loss in an isogenic genetic background, hence avoiding confounding genetic factors. Metabolic differences among different KRAS mutations might play a role in their different responses to anticancer treatments and hence could be exploited as novel metabolic vulnerabilities to develop more effective therapies against oncogenic KRAS.

Keywords:  Cells; Colorectal cancer; HCT116; KRAS; Metabolic profiling; Metabolomics; Metabonomics; Mutations; NMR

DOI:  https://doi.org/10.1007/s11306-021-01852-w
Metabolites. 2021 Oct 31. pii: 755. [Epub ahead of print]11(11):

Glutamine Homeostasis and Its Role in the Adaptive Strategies of the Blind Mole Rat, Spalax.

Dmitry Miskevich, Anastasia Chaban, Maria Dronina, Ifat Abramovich, Eyal Gottlieb, Imad Shams.

  Oxidative metabolism is fine-tuned machinery that combines two tightly coupled fluxes of glucose and glutamine-derived carbons. Hypoxia interrupts the coordination between the metabolism of these two nutrients and leads to a decrease of the system efficacy and may eventually cause cell death. The subterranean blind mole rat, Spalax, is an underexplored, underground, hypoxia-tolerant mammalian group which spends its life under sharply fluctuating oxygen levels. Primary Spalax cells are an exceptional model to study the metabolic strategies that have evolved in mammals inhabiting low-oxygen niches. In this study we explored the metabolic frame of glutamine (Gln) homeostasis in Spalax skin cells under normoxic and hypoxic conditions and their impacts on the metabolism of rat cells. Targeted metabolomics employing liquid chromatography and mass spectrometry (LC-MS) was used to track the fate of heavy glutamine carbons (13C5 Gln) after 24 h under normoxia or hypoxia (1% O2). Our results indicated that large amounts of glutamine-originated carbons were detected as proline (Pro) and hydroxyproline (HPro) in normoxic Spalax cells with a further increase under hypoxia, suggesting a strategy for reduced Gln carbons storage in proteins. The intensity of the flux and the presence of HPro suggests collagen as a candidate protein that is most abundant in animals, and as the primary source of HPro. An increased conversion of αKG to 2 HG that was indicated in hypoxic Spalax cells prevents the degradation of hypoxia-inducible factor 1α (HIF-1α) and, consequently, maintains cytosolic and mitochondrial carbons fluxes that were uncoupled via inhibition of the pyruvate dehydrogenase complex. A strong antioxidant defense in Spalax cells can be attributed, at least in part, to the massive usage of glutamine-derived glutamate for glutathione (GSH) production. The present study uncovers additional strategies that have evolved in this unique mammal to support its hypoxia tolerance, and probably contribute to its cancer resistance, longevity, and healthy aging.

Keywords:  GSH; adaptation; bioenergetics; glutamine; hypoxia; metabolome; proline cycle

DOI:  https://doi.org/10.3390/metabo11110755
Front Cell Dev Biol. 2021 ;9 724059

HIF1 and ID1 Interplay Confers Adaptive Survival to HIF1α-Inhibition.

Hao Geng, Hyun-Kyung Ko, Janet Pittsenbarger, Christopher T Harvey, Changhui Xue, Qiong Liu, Sadie Wiens, Sushant K Kachhap, Tomasz M Beer, David Z Qian.

  Hypoxia is a universal pathological feature of solid tumors. Hypoxic tumor cells acquire metastatic and lethal phenotypes primarily through the activities of hypoxia-inducible factor 1 alpha (HIF1α). Therefore, HIF1α is considered as a promising therapeutic target. However, HIF inhibitors have not proven to be effective in clinical testing. The underlying mechanism is unclear. We report that oncogenic protein ID1 is upregulated in hypoxia by HIF1α shRNA or pharmacological inhibitors. In turn, ID1 supports tumor growth in hypoxia in vitro and in xenografts in vivo, conferring adaptive survival response and resistance. Mechanistically, ID1 proteins interfere HIF1-mediated gene transcription activation, thus ID1 protein degradation is accelerated by HIF1α-dependent mechanisms in hypoxia. Inhibitions of HIF1α rescues ID1, which compensates the loss of HIF1α by the upregulation of GLS2 and glutamine metabolism, thereby switching the metabolic dependency of HIF1α -inhibited cells from glucose to glutamine.

Keywords:  HIF1; ID1; hypoxia; resistance; targeted-treatment

DOI:  https://doi.org/10.3389/fcell.2021.724059
Biomolecules. 2021 Nov 10. pii: 1666. [Epub ahead of print]11(11):

An Asp to Strike Out Cancer? Therapeutic Possibilities Arising from Aspartate's Emerging Roles in Cell Proliferation and Survival.

Iiro Taneli Helenius, Hanumantha Rao Madala, Jing-Ruey Joanna Yeh.

  A better understanding of the metabolic constraints of a tumor may lead to more effective anticancer treatments. Evidence has emerged in recent years shedding light on a crucial aspartate dependency of many tumor types. As a precursor for nucleotide synthesis, aspartate is indispensable for cell proliferation. Moreover, the malate-aspartate shuttle plays a key role in redox balance, and a deficit in aspartate can lead to oxidative stress. It is now recognized that aspartate biosynthesis is largely governed by mitochondrial metabolism, including respiration and glutaminolysis in cancer cells. Therefore, under conditions that suppress mitochondrial metabolism, including mutations, hypoxia, or chemical inhibitors, aspartate can become a limiting factor for tumor growth and cancer cell survival. Notably, aspartate availability has been associated with sensitivity or resistance to various therapeutics that are presently in the clinic or in clinical trials, arguing for a critical need for more effective aspartate-targeting approaches. In this review, we present current knowledge of the metabolic roles of aspartate in cancer cells and describe how cancer cells maintain aspartate levels under different metabolic states. We also highlight several promising aspartate level-modulating agents that are currently under investigation.

Keywords:  GOT1; alpha-ketoglutarate; asparagine; aspartate; cancer metabolism; glutaminase; hypoxia; mitochondrial DNA mutation; mitochondrial respiration; oxidative phosphorylation

DOI:  https://doi.org/10.3390/biom11111666
Front Oncol. 2021 ;11 756888

Cancer Stem Cells: Metabolic Characterization for Targeted Cancer Therapy.

Jasmeet Kaur, Shalmoli Bhattacharyya.

  The subpopulation of cancer stem cells (CSCs) within tumor bulk are known for tumor recurrence and metastasis. CSCs show intrinsic resistance to conventional therapies and phenotypic plasticity within the tumor, which make these a difficult target for conventional therapies. CSCs have different metabolic phenotypes based on their needs as compared to the bulk cancer cells. CSCs show metabolic plasticity and constantly alter their metabolic state between glycolysis and oxidative metabolism (OXPHOS) to adapt to scarcity of nutrients and therapeutic stress. The metabolic characteristics of CSCs are distinct compared to non-CSCs and thus provide an opportunity to devise more effective strategies to target CSCs. Mechanism for metabolic switch in CSCs is still unravelled, however existing evidence suggests that tumor microenvironment affects the metabolic phenotype of cancer cells. Understanding CSCs metabolism may help in discovering new and effective clinical targets to prevent cancer relapse and metastasis. This review summarises the current knowledge of CSCs metabolism and highlights the potential targeted treatment strategies.

Keywords:  OxPhos; cancer stem cell; glucose; glutamine; metabolism

DOI:  https://doi.org/10.3389/fonc.2021.756888
Mar Drugs. 2021 Oct 20. pii: 588. [Epub ahead of print]19(11):

Discovery of GOT1 Inhibitors from a Marine-Derived Aspergillus terreus That Act against Pancreatic Ductal Adenocarcinoma.

Shan Yan, Changxing Qi, Wei Song, Qianqian Xu, Lianghu Gu, Weiguang Sun, Yonghui Zhang.

  Pancreatic ductal adenocarcinoma (PDAC) is a devastating digestive system carcinoma with high incidence and death rates. PDAC cells are dependent on the Gln metabolism, which can preferentially utilize glutamic oxaloacetate transaminase 1 (GOT1) to maintain the redox homeostasis of cancer cells. Therefore, small molecule inhibitors targeting GOT1 can be used as a new strategy for developing cancer therapies. In this study, 18 butyrolactone derivatives (1-18) were isolated from a marine-derived Aspergillus terreus, and asperteretone B (5), aspulvinone H (AH, 6), and (+)-3',3'-di-(dimethylallyl)-butyrolactone II (12) were discovered to possess significant GOT1-inhibitory activities in vitro, with IC50 values of (19.16 ± 0.15), (5.91 ± 0.04), and (26.38 ± 0.1) µM, respectively. Significantly, the molecular mechanism of the crystal structure of GOT1-AH was elucidated, wherein AH and the cofactor pyrido-aldehyde 5-phosphate competitively bound to the active sites of GOT1. More importantly, although the crystal structure of GOT1 has been discovered, the complex structure of GOT1 and its inhibitors has never been obtained, and the crystal structure of GOT1-AH is the first reported complex structure of GOT1/inhibitor. Further in vitro biological study indicated that AH could suppress glutamine metabolism, making PDAC cells sensitive to oxidative stress and inhibiting cell proliferation. More significantly, AH exhibited potent in vivo antitumor activity in an SW1990-cell-induced xenograft model. These findings suggest that AH could be considered as a promising lead molecule for the development of anti-PDAC agents.

Keywords:  GOT1 enzyme; X-ray crystallography; glutamine metabolism; natural products; pancreatic ductal adenocarcinoma cells

DOI:  https://doi.org/10.3390/md19110588
Exp Eye Res. 2021 Nov 17. pii: S0014-4835(21)00411-5. [Epub ahead of print]213 108845

Glyceraldehyde-3-phosphate dehydrogenase and glutamine synthetase inhibition in the presence of pro-inflammatory cytokines contribute to the metabolic imbalance of diabetic retinopathy.

Gaganashree Shivashankar, Julie C Lim, Monica L Acosta.

  Diabetic retinopathy (DR) is the leading cause of vision impairment in working age adults. In addition to hyperglycemia, retinal inflammation is an important driving factor for DR development. Although DR is clinically described as diabetes-induced damage to the retinal blood vessels, several studies have reported that metabolic dysregulation occurs in the retina prior to the development of microvascular damage. The two most commonly affected metabolic pathways in diabetic conditions are glycolysis and the glutamate pathway. We investigated the role of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and glutamine synthetase (GS) in an in-vitro model of DR incorporating high glucose and pro-inflammatory cytokines. We found that GAPDH and GS enzyme activity were not significantly affected in hyperglycemic conditions or after exposure to cytokines alone, but were significantly decreased in the DR model. This confirmed that pro-inflammatory cytokines IL-1β and TNFα enhance the hyperglycemic metabolic deficit. We further investigated metabolite and amino acid levels after specific pharmacological inhibition of GAPDH or GS in the absence/presence of pro-inflammatory cytokines. The results indicate that GAPDH inhibition increased glucose and addition of cytokines increased lactate and ATP levels and reduced glutamate levels. GS inhibition did not alter retinal metabolite levels but the addition of cytokines increased ATP levels and caused glutamate accumulation in Müller cells. We conclude that it is the action of pro-inflammatory cytokines concomitantly with the inhibition of the glycolytic or GS mediated glutamate recycling that contribute to metabolic dysregulation in DR. Therefore, in the absence of good glycemic control, therapeutic interventions aimed at regulating inflammation may prevent the onset of early metabolic imbalance in DR.

Keywords:  Diabetic retinopathy; Glutamate recycling; Glutamine synthetase; Glyceraldehyde 3-phosphate dehydrogenase; Glycolysis; Inflammation; Metabolic dysregulation; Retina

DOI:  https://doi.org/10.1016/j.exer.2021.108845
Eur J Mass Spectrom (Chichester). 2021 Nov 22. 14690667211057996

Discovery of metabolomic biomarkers for discriminating platinum-sensitive and platinum-resistant ovarian cancer by using GC-MS.

Evren C Eroglu, Sule Tunug, Omer Faruk Geckil, Umran Kucukgoz Gulec, Mehmet Ali Vardar, Semra Paydas.

  This study aims to determine ovarian cancer (OC) patients with platinum resistance for alternative treatment protocols by using metabolomic methodologies. Urine and serum samples of platinum-resistant and platinum-sensitive OC were analyzed using GC-MS. After data processing of GC-MS raw data, multivariate analyses were performed to interpret complex data for biologically meaningful information and to identify the biomarkers that cause differences between two groups. The biomarkers were verified after univariate, multivariate, and ROC analysis. Finally, metabolomic pathways related to group separations were specified. The results of biomarker analysis showed that 3,4-dihydroxyphenylacetic acid, 4-hydroxybutyric acid, L-threonine, D- mannose, and sorbitol metabolites were potential biomarkers in urine samples. In serum samples, L-arginine, linoleic acid, L-glutamine, and hypoxanthine were identified as important biomarkers. R2Y, Q2, AUC, sensitivity and specificity values of platinum-resistant and sensitive OC patients' urine and serum samples were 0.85, 0.545, 0.844, 91.30%, 81.08 and 0.570, 0.206, 0.743, 77.78%, 74.28%, respectively. In metabolic pathway analysis of urine samples, tyrosine metabolism and fructose and mannose metabolism were found to be statistically significant (p < 0.05) for the discrimination of the two groups. While 3,4-dihydroxyphenylacetic acid, L-tyrosine, and fumaric acid metabolites were effective in tyrosine metabolism. D-sorbitol and D-mannose metabolites were significantly important in fructose and mannose metabolism. However, seven metabolomic pathways were significant (p < 0.05) in serum samples. In terms of p-value, L-glutamine in the nitrogen metabolic pathway from the first three pathways; L-glutamine and pyroglutamic acid metabolites in D-glutamine and D-glutamate metabolism. In the arginine and proline metabolic pathway, L-arginine, L-proline, and L-ornithine metabolites differed significantly between the two groups.

Keywords:  GC-MS; OPLS-DA; ROC analysis; metabolomics; ovarian cancer; pathway analysis; platinum-resistant; platinum-sensitive; serum; urine

DOI:  https://doi.org/10.1177/14690667211057996
Cell Rep. 2021 Nov 23. pii: S2211-1247(21)01519-9. [Epub ahead of print]37(8): 110037

Glucose metabolism and pyruvate carboxylase enhance glutathione synthesis and restrict oxidative stress in pancreatic islets.

Accalia Fu, Lara van Rooyen, Lindsay Evans, Nina Armstrong, Daina Avizonis, Tatsuya Kin, Gregory H Bird, Anita Reddy, Edward T Chouchani, Marc Liesa-Roig, Loren D Walensky, A M James Shapiro, Nika N Danial.

  Glucose metabolism modulates the islet β cell responses to diabetogenic stress, including inflammation. Here, we probed the metabolic mechanisms that underlie the protective effect of glucose in inflammation by interrogating the metabolite profiles of primary islets from human donors and identified de novo glutathione synthesis as a prominent glucose-driven pro-survival pathway. We find that pyruvate carboxylase is required for glutathione synthesis in islets and promotes their antioxidant capacity to counter inflammation and nitrosative stress. Loss- and gain-of-function studies indicate that pyruvate carboxylase is necessary and sufficient to mediate the metabolic input from glucose into glutathione synthesis and the oxidative stress response. Altered redox metabolism and cellular capacity to replenish glutathione pools are relevant in multiple pathologies beyond obesity and diabetes. Our findings reveal a direct interplay between glucose metabolism and glutathione biosynthesis via pyruvate carboxylase. This metabolic axis may also have implications in other settings where sustaining glutathione is essential.

Keywords:  ROS; glucose; glutathione; inflammation; nitrosative stress; oxidative stress; pancreatic islets; pyruvate carboxylase

DOI:  https://doi.org/10.1016/j.celrep.2021.110037