bims-glucam 2020-12-20 papers

bims-glucam

Biomed News

on Glutamine cancer metabolism

Issue of 2020–12–20
twenty papers selected by
Sreeparna Banerjee, Middle East Technical University

Downregulation of Glutamine Synthetase, not glutaminolysis, is responsible for glutamine addiction in Notch1-driven acute lymphoblastic leukemia.
In vivo assessment of glutamine anaplerosis into the TCA cycle in human pre-malignant and malignant clonal plasma cells.
De novo synthesis and salvage pathway coordinately regulate polyamine homeostasis and determine T cell proliferation and function.
Characterization of Kinetic Isotope Effects and Label Loss in Deuterium-Based Isotopic Labeling Studies.
Metabolic substrate utilization in stress-induced immune cells.
Lactate Limits T Cell Proliferation via the NAD(H) Redox State.
Metabolic Regulation of Epigenetic Modifications and Cell Differentiation in Cancer.
FXR mediates T cell-intrinsic responses to reduced feeding during infection.
Structural and Kinetic Analyses Reveal the Dual Inhibition Modes of Ornithine Aminotransferase by (1S,3S)-3-Amino-4-(hexafluoropropan-2-ylidenyl)-cyclopentane-1-carboxylic Acid (BCF3).
Is nuclear sirtuin SIRT6 a master regulator of immune function?
Nrf2 Mediates Metabolic Reprogramming in Non-Small Cell Lung Cancer.
Structural Insight into the Contributions of the N-Terminus and Key Active-Site Residues to the Catalytic Efficiency of Glutamine Synthetase 2.
Tumor Reliance on Cytosolic versus Mitochondrial One-Carbon Flux Depends on Folate Availability.
Redox regulation of immunometabolism.
From Glucose to Lactate and Transiting Intermediates Through Mitochondria, Bypassing Pyruvate Kinase: Considerations for Cells Exhibiting Dimeric PKM2 or Otherwise Inhibited Kinase Activity.
Upregulation of PI3K/AKT/PTEN pathway is correlated with glucose and glutamine metabolic dysfunction during tamoxifen resistance development in MCF-7 cells.
A Novel Biomarker of Neuronal Glutamate Metabolism in Nonhuman Primates Using Localized 1H-Magnetic Resonance Spectroscopy: Development and Effects of BNC375, an α7 Nicotinic Acetylcholine Receptor Positive Allosteric Modulator.
Transarterial chemoembolization enhances programmed death 1 and programmed death-ligand 1 expression in hepatocellular carcinoma.
Effects of intestinal trefoil factor on intestinal mucus barrier in burned mice.
Metabolomic and quality data for early and late passages of an antibody-producing industrial CHO cell line.

Mol Oncol. 2020 Dec 12.

Downregulation of Glutamine Synthetase, not glutaminolysis, is responsible for glutamine addiction in Notch1-driven acute lymphoblastic leukemia.

Tra Ly Nguyen, Marie-Julie Nokin, Silvia Terés, Mercedes Tomé, Clément Bodineau, Oriane Galmar, Jean-Max Pasquet, Benoit Rousseau, Sebastian van Liempd, Juan Manuel Falcon-Perez, Elodie Richard, Elodie Muzotte, Hamid-Reza Rezvani, Muriel Priault, Marion Bouchecareilh, Isabelle Redonnet-Vernhet, Julien Calvo, Benjamin Uzan, Françoise Pflumio, Patricia Fuentes, Maria L Toribio, Abdel-Majid Khatib, Pierre Soubeyran, Piedad Del Socorro Murdoch, Raúl V Durán.

  The cellular receptor Notch1 is a central regulator of T-cell development, and as a consequence, Notch1 pathway appears upregulated in >65% of the cases of T-cell acute lymphoblastic leukemia (T-ALL). However, strategies targeting Notch1 signaling render only modest results in the clinic due to treatment resistance and severe side effects. While many investigations reported the different aspects of tumor cell growth and leukemia progression controlled by Notch1, less is known regarding the modifications of cellular metabolism induced by Notch1 upregulation in T-ALL. Previously, glutaminolysis inhibition has been proposed to synergise with anti-Notch therapies in T-ALL models. In this work, we report that Notch1 upregulation in T-ALL induced a change in the metabolism of the important amino acid glutamine, preventing glutamine synthesis through the downregulation of glutamine synthetase. Downregulation of glutamine synthetase was responsible for glutamine addiction in Notch1-driven T-ALL both in vitro and in vivo. Our results also confirmed an increase in glutaminolysis mediated by Notch1. Increased glutaminolysis resulted in the activation of the mTORC1 pathway, a central controller of cell growth. However, glutaminolysis did not play any role in Notch1-induced glutamine addiction. Finally, the combined treatment targeting mTORC1 and limiting glutamine availability had a synergistic effect to induce apoptosis and to prevent Notch1-driven leukemia progression. Our results placed glutamine limitation and mTORC1 inhibition as a potential therapy against Notch1-driven leukemia.

Keywords:  Notch1; T-cell acute lymphoblastic leukemia; glutamine; glutamine synthetase; mTORC1; metabolic addiction

DOI:  https://doi.org/10.1002/1878-0261.12877
Cancer Metab. 2020 Dec 11. 8(1): 29

In vivo assessment of glutamine anaplerosis into the TCA cycle in human pre-malignant and malignant clonal plasma cells.

Wilson I Gonsalves, Jin Sung Jang, Erik Jessen, Taro Hitosugi, Laura A Evans, Dragan Jevremovic, Xuan-Mai Pettersson, Alexander Graham Bush, Jaimee Gransee, Emilie I Anderson, Shaji K Kumar, K Sreekumaran Nair.

   BACKGROUND: Overexpression of c-Myc is required for the progression of pre-malignant plasma cells in monoclonal gammopathy of undetermined significance (MGUS) to malignant plasma cells in multiple myeloma (MM). c-Myc also increases glutamine anaplerosis into the tricarboxylic acid (TCA) cycle within cancer cells. Whether increased glutamine anaplerosis is associated with the progression of pre-malignant to malignant plasma cells is unknown.
METHODS: Human volunteers (N = 7) and patients with MGUS (N = 11) and MM (N = 12) were prospectively recruited to undergo an intravenous infusion of 13C-labeled glutamine followed by a bone marrow aspiration to obtain bone marrow cells and plasma.
RESULTS: Despite notable heterogeneity, stable isotope-resolved metabolomics (SIRM) revealed that the mean 13C-labeled glutamine anaplerosis into the TCA cycle was higher in malignant compared to pre-malignant bone marrow plasma cells relative to the remainder of their paired bone marrow mononuclear cells. RNA sequencing demonstrated a higher relative mRNA expression of c-Myc and glutamine transporters such as ASCT2 and SN2 in malignant compared to pre-malignant bone marrow plasma cells. Finally, higher quantitative levels of TCA cycle intermediates in the bone marrow plasma differentiated MM from MGUS patients.
CONCLUSION: Measurement of the in vivo activity of glutamine anaplerosis into the TCA cycle provides novel insight into the metabolic changes associated with the transformation of pre-malignant plasma cells in MGUS to malignant plasma cells in MM.
TRIAL REGISTRATION: NCT03384108 and NCT03119883.

Keywords:  Glutamine; Myeloma; Plasma cell malignancies; Stable isotope metabolomics

DOI:  https://doi.org/10.1186/s40170-020-00235-4
Sci Adv. 2020 Dec;pii: eabc4275. [Epub ahead of print]6(51):

De novo synthesis and salvage pathway coordinately regulate polyamine homeostasis and determine T cell proliferation and function.

Ruohan Wu, Xuyong Chen, Siwen Kang, Tingting Wang, Jn Rashida Gnanaprakasam, Yufeng Yao, Lingling Liu, Gaofeng Fan, Mark R Burns, Ruoning Wang.

Robust and effective T cell-mediated immune responses require proper allocation of metabolic resources through metabolic pathways to sustain the energetically costly immune response. As an essential class of polycationic metabolites ubiquitously present in all living organisms, the polyamine pool is tightly regulated by biosynthesis and salvage pathway. We demonstrated that arginine is a major carbon donor and glutamine is a minor carbon donor for polyamine biosynthesis in T cells. Accordingly, the dependence of T cells can be partially relieved by replenishing the polyamine pool. In response to the blockage of biosynthesis, T cells can rapidly restore the polyamine pool through a compensatory increase in extracellular polyamine uptake, indicating a layer of metabolic plasticity. Simultaneously blocking synthesis and uptake depletes the intracellular polyamine pool, inhibits T cell proliferation, and suppresses T cell inflammation, indicating the potential therapeutic value of targeting the polyamine pool for managing inflammatory and autoimmune diseases.

DOI: https://doi.org/10.1126/sciadv.abc4275
ACS Chem Neurosci. 2020 Dec 15.

Characterization of Kinetic Isotope Effects and Label Loss in Deuterium-Based Isotopic Labeling Studies.

Robin A de Graaf, Monique A Thomas, Kevin L Behar, Henk M De Feyter.

  Deuterium metabolic imaging (DMI) is a novel, 3D, magnetic resonance (MR)-based method to map metabolism of deuterated substrates in vivo. The replacement of protons with deuterons could potentially lead to kinetic isotope effects (KIEs) in which metabolic rates of deuterated substrates are reduced due to the presence of a heavier isotope. Knowledge of the extent of KIE in vivo and 2H label loss due to exchange reactions is required for DMI-based measurements of absolute metabolic rates. Here the deuterium KIE and label loss in vivo are investigated for glucose and acetate using a double substrate/double labeling strategy and 1H-decoupled 13C NMR in rat glioma cells and rat brain tissue metabolite extracts. The unique spectral patterns due to extensive 2H-13C and 13C-13C scalar couplings allow the identification of all possible metabolic products. The 2H label loss observed in lactate, glutamate, and glutamine of rat brain was 15.7 ± 2.6, 37.9 ± 1.1, and 41.5 ± 5.2% when using [6,6-2H2]-glucose as the metabolic substrate. For [2-2H3]-acetate, the 2H label loss in glutamate and glutamine was 14.4 ± 3.4 and 13.6 ± 2.2%, respectively, in excellent agreement with predicted values. Steady-state 2H label accumulation in the C4 position of glutamate and glutamine was contrasted by the absence of label accumulation in the C2 or C3 positions, indicating that during a full turn of the tricarboxylic acid cycle all 2H label is lost. The measured KIE was relatively small (4-6%) for both substrates and all measured metabolic products. These results pave the way for further development of quantitative DMI studies to generate metabolic flux maps in vivo.

Keywords:  Deuterium; acetate; glucose; kinetic isotope effect; label loss

DOI:  https://doi.org/10.1021/acschemneuro.0c00711
Intensive Care Med Exp. 2020 Dec 18. 8(Suppl 1): 28

Metabolic substrate utilization in stress-induced immune cells.

Xiaomin Zhang, Fabian Zink, Felix Hezel, Josef Vogt, Ulrich Wachter, Martin Wepler, Maurizio Loconte, Christine Kranz, Andreas Hellmann, Boris Mizaikoff, Peter Radermacher, Clair Hartmann.

  Immune cell activation leads to the acquisition of new functions, such as proliferation, chemotaxis, and cytokine production. These functional changes require continuous metabolic adaption in order to sustain ATP homeostasis for sufficient host defense. The bioenergetic demands are usually met by the interconnected metabolic pathways glycolysis, TCA cycle, and oxidative phosphorylation. Apart from glucose, other sources, such as fatty acids and glutamine, are able to fuel the TCA cycle.Rising evidence has shown that cellular metabolism has a direct effect on the regulation of immune cell functions. Thus, quiescent immune cells maintain a basal metabolic state, which shifts to an accelerated metabolic level upon immune cell activation in order to promote key effector functions.This review article summarizes distinct metabolic signatures of key immune cell subsets from quiescence to activation and demonstrates a methodical concept of how to assess cellular metabolic pathways. It further discusses why metabolic functions are of rising interest for translational research and how they can be affected by the underlying pathophysiological condition and/or therapeutic interventions.

Keywords:  Catecholamines; Glycolysis; Immunometabolism; Oxidative phosphorylation; Pentose phosphate pathway; Reactive oxygen species; Tricarboxylic acid cycle

DOI:  https://doi.org/10.1186/s40635-020-00316-0
Cell Rep. 2020 Dec 15. pii: S2211-1247(20)31489-3. [Epub ahead of print]33(11): 108500

Lactate Limits T Cell Proliferation via the NAD(H) Redox State.

William J Quinn, Jing Jiao, Tara TeSlaa, Jason Stadanlick, Zhonglin Wang, Liqing Wang, Tatiana Akimova, Alessia Angelin, Patrick M Schäfer, Michelle D Cully, Caroline Perry, Piotr K Kopinski, Lili Guo, Ian A Blair, Louis R Ghanem, Michael S Leibowitz, Wayne W Hancock, Edmund K Moon, Matthew H Levine, Evgeniy B Eruslanov, Douglas C Wallace, Joseph A Baur, Ulf H Beier.

  Immune cell function is influenced by metabolic conditions. Low-glucose, high-lactate environments, such as the placenta, gastrointestinal tract, and the tumor microenvironment, are immunosuppressive, especially for glycolysis-dependent effector T cells. We report that nicotinamide adenine dinucleotide (NAD+), which is reduced to NADH by lactate dehydrogenase in lactate-rich conditions, is a key point of metabolic control in T cells. Reduced NADH is not available for NAD+-dependent enzymatic reactions involving glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and 3-phosphoglycerate dehydrogenase (PGDH). We show that increased lactate leads to a block at GAPDH and PGDH, leading to the depletion of post-GAPDH glycolytic intermediates, as well as the 3-phosphoglycerate derivative serine that is known to be important for T cell proliferation. Supplementing serine rescues the ability of T cells to proliferate in the presence of lactate-induced reductive stress. Directly targeting the redox state may be a useful approach for developing novel immunotherapies in cancer and therapeutic immunosuppression.

Keywords:  3-phosphoglycerate; T cell metabolism; glycolysis; immunometabolism; lactate metabolism; nicotinamide adenine dinucleotide; redox metabolism; serine

DOI:  https://doi.org/10.1016/j.celrep.2020.108500
Cancers (Basel). 2020 Dec 16. pii: E3788. [Epub ahead of print]12(12):

Metabolic Regulation of Epigenetic Modifications and Cell Differentiation in Cancer.

Pasquale Saggese, Assunta Sellitto, Cesar A Martinez, Giorgio Giurato, Giovanni Nassa, Francesca Rizzo, Roberta Tarallo, Claudio Scafoglio.

  Metabolic reprogramming is a hallmark of cancer, with consistent rewiring of glucose, glutamine, and mitochondrial metabolism. While these metabolic alterations are adequate to meet the metabolic needs of cell growth and proliferation, the changes in critical metabolites have also consequences for the regulation of the cell differentiation state. Cancer evolution is characterized by progression towards a poorly differentiated, stem-like phenotype, and epigenetic modulation of the chromatin structure is an important prerequisite for the maintenance of an undifferentiated state by repression of lineage-specific genes. Epigenetic modifiers depend on intermediates of cellular metabolism both as substrates and as co-factors. Therefore, the metabolic reprogramming that occurs in cancer likely plays an important role in the process of the de-differentiation characteristic of the neoplastic process. Here, we review the epigenetic consequences of metabolic reprogramming in cancer, with particular focus on the role of mitochondrial intermediates and hypoxia in the regulation of cellular de-differentiation. We also discuss therapeutic implications.

Keywords:  cancer epigenetics; cancer metabolism; cell differentiation in cancer; mitochondrial metabolism

DOI:  https://doi.org/10.3390/cancers12123788
Proc Natl Acad Sci U S A. 2020 Dec 14. pii: 202020619. [Epub ahead of print]

FXR mediates T cell-intrinsic responses to reduced feeding during infection.

Clarissa Campbell, Francois Marchildon, Anthony J Michaels, Naofumi Takemoto, Joris van der Veeken, Michail Schizas, Yuri Pritykin, Christina S Leslie, Andrew M Intlekofer, Paul Cohen, Alexander Y Rudensky.

  Reduced nutrient intake is a widely conserved manifestation of sickness behavior with poorly characterized effects on adaptive immune responses. During infectious challenges, naive T cells encountering their cognate antigen become activated and differentiate into highly proliferative effector T cells. Despite their evident metabolic shift upon activation, it remains unclear how effector T cells respond to changes in nutrient availability in vivo. Here, we show that spontaneous or imposed feeding reduction during infection decreases the numbers of splenic lymphocytes. Effector T cells showed cell-intrinsic responses dependent on the nuclear receptor Farnesoid X Receptor (FXR). Deletion of FXR in T cells prevented starvation-induced loss of lymphocytes and increased effector T cell fitness in nutrient-limiting conditions, but imparted greater weight loss to the host. FXR deficiency increased the contribution of glutamine and fatty acids toward respiration and enhanced cell survival under low-glucose conditions. Provision of glucose during anorexia of infection rescued effector T cells, suggesting that this sugar is a limiting nutrient for activated lymphocytes and that alternative fuel usage may affect cell survival in starved animals. Altogether, we identified a mechanism by which the host scales immune responses according to food intake, featuring FXR as a T cell-intrinsic sensor.

Keywords:  FXR; T cells; anorexia; infection

DOI:  https://doi.org/10.1073/pnas.2020619117
ACS Chem Biol. 2020 Dec 14.

Structural and Kinetic Analyses Reveal the Dual Inhibition Modes of Ornithine Aminotransferase by (1S,3S)-3-Amino-4-(hexafluoropropan-2-ylidenyl)-cyclopentane-1-carboxylic Acid (BCF3).

Arseniy Butrin, Brett A Beaupre, Noel Kadamandla, Peidong Zhao, Sida Shen, Richard B Silverman, Graham R Moran, Dali Liu.

Hepatocellular carcinoma (HCC) is the most common form of liver cancer and the leading cause of death among people with cirrhosis. HCC is typically diagnosed in advanced stages when tumors are resistant to both radio- and chemotherapy. Human ornithine aminotransferase (hOAT) is a pyridoxal-5'-phosphate (PLP)-dependent enzyme involved in glutamine and proline metabolism. Because hOAT is overexpressed in HCC cells and a contributing factor for the uncontrolled cellular division that propagates malignant tumors (Ueno et al. J. Hepatol. 2014, 61, 1080-1087), it is a potential drug target for the treatment of HCC. (1S,3S)-3-Amino-4-(hexafluoropropan-2-ylidenyl)-cyclopentane-1-carboxylic acid (BCF3) has been shown in animal models to slow the progression of HCC by acting as a selective and potent mechanism-based inactivator of OAT (Zigmond et al. ACS Med. Chem. Lett. 2015, 6, 840-844). Previous studies have shown that the BCF3-hOAT reaction has a bifurcation in which only 8% of the inhibitor inactivates the enzyme while the remaining 92% ultimately acts as a substrate and undergoes hydrolysis to regenerate the active PLP form of the enzyme. In this manuscript, the rate-limiting step of the inactivation mechanism was determined by stopped-flow spectrophotometry and time-dependent 19F NMR experiments to be the decay of a long-lived external aldimine species. A crystal structure of this transient complex revealed both the structural basis for fractional irreversible inhibition and the principal mode of inhibition of hOAT by BCF3, which is to trap the enzyme in this transient but quasi-stable external aldimine form.

DOI: https://doi.org/10.1021/acschembio.0c00728
Am J Physiol Endocrinol Metab. 2020 Dec 14.

Is nuclear sirtuin SIRT6 a master regulator of immune function?

Vinodkumar B Pillai, Mahesh P Gupta.

  The ability to ward off pathogens with minimal damage to the host determines the immune system's robustness. Multiple factors, including pathogen processing, identification, secretion of mediator and effector molecules, and immune cell proliferation and differentiation into various subsets, constitute the success of mounting an effective immune response. Cellular metabolism controls all of these intricate processes. Cells utilize diverse fuel sources and switch back and forth between different metabolic pathways depending on their energy needs. The three most critical metabolic pathways on which immune cells depend to meet their energy needs are oxidative metabolism, glycolysis, and glutaminolysis. Dynamic switching between these metabolic pathways is needed for optimal function of the immune cells. Moreover, switching between these metabolic pathways needs to be tightly regulated to achieve the best results. Immune cells depend on the Warburg effect for their growth, proliferation, secretory, and effector functions. Here, we hypothesize that the sirtuin, SIRT6, could be a negative regulator of the Warburg effect. We also postulate that SIRT6 could act as a master regulator of immune cell metabolism and function by regulating critical signaling pathways.

Keywords:  Cell-Signaling; Immune cells; Metabolism; SIRT6; Warburg effect

DOI:  https://doi.org/10.1152/ajpendo.00483.2020
Front Oncol. 2020 ;10 578315

Nrf2 Mediates Metabolic Reprogramming in Non-Small Cell Lung Cancer.

Jiangang Zhao, Xu Lin, Di Meng, Liping Zeng, Runzhou Zhuang, Sha Huang, Wang Lv, Jian Hu.

  Nuclear factor erythroid-2-related factor-2 (NFE2L2/Nrf2) is a transcription factor that regulates the expression of antioxidant genes. Both Kelch-like ECH-associated protein 1 (Keap1) mutations and Nrf2 mutations contribute to the activation of Nrf2 in non-small cell lung cancer (NSCLC). Nrf2 activity is associated with poor prognosis in NSCLC. Metabolic reprogramming represents a cancer hallmark. Increasing studies reveal that Nrf2 activation promotes metabolic reprogramming in cancer. In this review, we discuss the underlying mechanisms of Nrf2-mediated metabolic reprogramming and elucidate its role in NSCLC. Inhibition of Nrf2 can alter metabolic processes, thus suppress tumor growth, prevent metastasis, and increase sensitivity to chemotherapy in NSCLC. In conclusion, Nrf2 may serve as a therapeutic target for the treatment of NSCLC.

Keywords:  Kelch-like ECH-associated protein 1; metabolic reprogramming; non-small cell lung cancer; nuclear factor erythroid-2–related factor-2; reduction-oxidation balance

DOI:  https://doi.org/10.3389/fonc.2020.578315
Biomolecules. 2020 Dec 14. pii: E1671. [Epub ahead of print]10(12):

Structural Insight into the Contributions of the N-Terminus and Key Active-Site Residues to the Catalytic Efficiency of Glutamine Synthetase 2.

Wen-Ting Chen, Hsin-Yu Yang, Chih-Yu Lin, Yi-Zong Lee, Szu-Chin Ma, Wei-Cheng Chen, Hsien-Sheng Yin.

  Glutamine synthetase (GS) catalyzes the condensation of ammonia and glutamate, along with ATP, to form glutamine. Despite extensive studies on GSs from eukaryotes and prokaryotes, the roles of the N-terminus and other structural features in catalysis remain unclear. Here we report the decameric structure of Drosophila melanogaster GS 2 (DmGS2). The N-terminal short helices, α1 and α2, constitute a meander region, and form hydrogen bonds with residues 3-5 in the N-terminal loop, which are not present in the GSs of other species. Deletion of α1 or α1-α2 inactivates DmGS2. Notably, the Arg4 in each monomer of one pentamer forms hydrogen bonds with Glu7, and Asp8 in the adjacent monomer of the other pentamer. Replacement of Arg4 with Asp (R4D) abolishes activity. Analytical ultracentrifugation revealed that Arg4 is crucial for oligomerization. Circular dichroism spectra revealed that R4D may alter the secondary structure. We mutated key residues to identify the substrate-binding site. As Glu140 binds glutamate and Glu311 binds ammonia, mutants E140A and E311A have little activity. Conversely, mutant P214A (P contributes to ATP binding) has higher activity than wild-type DmGS2. These findings expand the understanding of the structural and functional features of the N-terminal meander region of DmGS2 and the residues important for catalytic efficiency.

Keywords:  Drosophila melanogaster; circular dichroism; crystal structure; enzyme kinetics; glutamine synthetase

DOI:  https://doi.org/10.3390/biom10121671
Cell Metab. 2020 Dec 10. pii: S1550-4131(20)30657-4. [Epub ahead of print]

Tumor Reliance on Cytosolic versus Mitochondrial One-Carbon Flux Depends on Folate Availability.

Won Dong Lee, Anna Chiara Pirona, Boris Sarvin, Alon Stern, Keren Nevo-Dinur, Elazar Besser, Nikita Sarvin, Shoval Lagziel, Dzmitry Mukha, Shachar Raz, Elina Aizenshtein, Tomer Shlomi.

  Folate metabolism supplies one-carbon (1C) units for biosynthesis and methylation and has long been a target for cancer chemotherapy. Mitochondrial serine catabolism is considered the sole contributor of folate-mediated 1C units in proliferating cancer cells. Here, we show that under physiological folate levels in the cell environment, cytosolic serine-hydroxymethyltransferase (SHMT1) is the predominant source of 1C units in a variety of cancers, while mitochondrial 1C flux is overly repressed. Tumor-specific reliance on cytosolic 1C flux is associated with poor capacity to retain intracellular folates, which is determined by the expression of SLC19A1, which encodes the reduced folate carrier (RFC). We show that silencing SHMT1 in cells with low RFC expression impairs pyrimidine biosynthesis and tumor growth in vivo. Overall, our findings reveal major diversity in cancer cell utilization of the cytosolic versus mitochondrial folate cycle across tumors and SLC19A1 expression as a marker for increased reliance on SHMT1.

Keywords:  SHMT; cancer metabolism; folate cycle; in vivo; isotope tracing; metabolomics; mitochondria; one-carbon flux; physiologic medium; reduced folate carrier; serine hydroxymethyltransferase

DOI:  https://doi.org/10.1016/j.cmet.2020.12.002
Nat Rev Immunol. 2020 Dec 18.

Redox regulation of immunometabolism.

Jonathan Muri, Manfred Kopf.

Metabolic pathways and redox reactions are at the core of life. In the past decade(s), numerous discoveries have shed light on how metabolic pathways determine the cellular fate and function of lymphoid and myeloid cells, giving rise to an area of research referred to as immunometabolism. Upon activation, however, immune cells not only engage specific metabolic pathways but also rearrange their oxidation-reduction (redox) system, which in turn supports metabolic reprogramming. In fact, studies addressing the redox metabolism of immune cells are an emerging field in immunology. Here, we summarize recent insights revealing the role of reactive oxygen species (ROS) and the differential requirement of the main cellular antioxidant pathways, including the components of the thioredoxin (TRX) and glutathione (GSH) pathways, as well as their transcriptional regulator NF-E2-related factor 2 (NRF2), for proliferation, survival and function of T cells, B cells and macrophages.

DOI: https://doi.org/10.1038/s41577-020-00478-8
Front Physiol. 2020 ;11 543564

From Glucose to Lactate and Transiting Intermediates Through Mitochondria, Bypassing Pyruvate Kinase: Considerations for Cells Exhibiting Dimeric PKM2 or Otherwise Inhibited Kinase Activity.

Christos Chinopoulos.

  A metabolic hallmark of many cancers is the increase in glucose consumption coupled to excessive lactate production. Mindful that L-lactate originates only from pyruvate, the question arises as to how can this be sustained in those tissues where pyruvate kinase activity is reduced due to dimerization of PKM2 isoform or inhibited by oxidative/nitrosative stress, posttranslational modifications or mutations, all widely reported findings in the very same cells. Hereby 17 pathways connecting glucose to lactate bypassing pyruvate kinase are reviewed, some of which transit through the mitochondrial matrix. An additional 69 converging pathways leading to pyruvate and lactate, but not commencing from glucose, are also examined. The minor production of pyruvate and lactate by glutaminolysis is scrutinized separately. The present review aims to highlight the ways through which L-lactate can still be produced from pyruvate using carbon atoms originating from glucose or other substrates in cells with kinetically impaired pyruvate kinase and underscore the importance of mitochondria in cancer metabolism irrespective of oxidative phosphorylation.

Keywords:  Warburg effect; cancer; glycolysis; lactate dehydrogenase; metabolomics; mitochondria; oncometabolism

DOI:  https://doi.org/10.3389/fphys.2020.543564
Sci Rep. 2020 Dec 14. 10(1): 21933

Upregulation of PI3K/AKT/PTEN pathway is correlated with glucose and glutamine metabolic dysfunction during tamoxifen resistance development in MCF-7 cells.

Lama Hamadneh, Rama Abuarqoub, Ala Alhusban, Mohamad Bahader.

Tamoxifen resistance is emerging as a big challenge in endocrine therapy of luminal A breast cancer patients. In this study, we aimed to determine the molecular changes of PI3K/AKT/PTEN signaling pathway during tamoxifen-resistance development using gradually increased doses of tamoxifen in one model, while fixing tamoxifen treatment dose at 35 μM for several times in the second model. An upregulation of AKT/PI3K genes was noticed at 30 μM tamoxifen concentration in cells treated with a gradual increase of tamoxifen doses. In the second model, significant upregulation of AKT1 was seen in cells treated with 35 μM tamoxifen for three times. All genes studied showed a significant increase in expression in resistant cells treated with 50 µM and 35 µM six times tamoxifen. These genes' upregulation was accompanied by PTEN and GSK3 ß genes' down-regulation, and it was in correlation to the changes in the metabolic rate of glucose in tamoxifen-resistant models. A significant increase in glucose consumption rate from culture media was observed in tamoxifen resistant cells with the highest consumption rate reported in the first day of culturing. Increased glucose consumption rates were also correlated with GLUL significant gene expression and non-significant change in c-MYC gene expression that may lead to increased endogenous glutamine synthesis. As a result, several molecular and metabolic changes precede acquired tamoxifen resistance could be used as resistance biomarkers or targets to reverse tamoxifen resistance.

DOI: https://doi.org/10.1038/s41598-020-78833-x
Biol Psychiatry Cogn Neurosci Neuroimaging. 2020 Sep 29. pii: S2451-9022(20)30283-4. [Epub ahead of print]

A Novel Biomarker of Neuronal Glutamate Metabolism in Nonhuman Primates Using Localized 1H-Magnetic Resonance Spectroscopy: Development and Effects of BNC375, an α7 Nicotinic Acetylcholine Receptor Positive Allosteric Modulator.

Corin O Miller, Liza T Gantert, Stephen F Previs, Ying Chen, Kenneth D Anderson, Justina M Thomas, Gerard Sanacora, Jason M Uslaner, Douglas L Rothman, Graeme F Mason.

   BACKGROUND: The development of treatments for cognitive deficits associated with central nervous system disorders is currently a significant medical need. Despite the great need for such therapeutics, a significant challenge in the drug development process is the paucity of robust biomarkers to assess target modulation and guide clinical decisions. We developed a novel, translatable biomarker of neuronal glutamate metabolism, the 13C-glutamate+glutamine (Glx) H3:H4 labeling ratio, in nonhuman primates using localized 1H-magnetic resonance spectroscopy combined with 13C-glucose infusions.
METHODS: We began with numerical simulations in an established model of brain glutamate metabolism, showing that the 13C-Glx H3:H4 ratio should be a sensitive biomarker of neuronal tricarboxylic acid cycle activity, a key measure of overall neuronal metabolism. We showed that this biomarker can be measured reliably using a standard 1H-magnetic resonance spectroscopy method (point-resolved spectroscopy sequence/echo time = 20 ms), obviating the need for specialized hardware and pulse sequences typically used with 13C-magnetic resonance spectroscopy, thus improving overall clinical translatability. Finally, we used this biomarker in 8 male rhesus macaques before and after administration of the compound BNC375, a positive allosteric modulator of the α7 nicotinic acetylcholine receptor that enhances glutamate signaling ex vivo and elicits procognitive effects in preclinical species.
RESULTS: The 13C-Glx H3:H4 ratios in the monkeys showed that BNC375 increases neuronal metabolism in nonhuman primates in vivo, detectable on an individual basis.
CONCLUSIONS: This study demonstrates that the ratio of 13C-Glx H3:H4 labeling is a biomarker that may provide an objective readout of compounds affecting glutamatergic neurotransmission and could improve decision making for the development of therapeutic agents.

Keywords:  Biomarker; Glutamate; Imaging; MRS; Nicotinic acetylcholine receptor; Positive allosteric modulator

DOI:  https://doi.org/10.1016/j.bpsc.2020.09.014
Histopathology. 2020 Dec 16.

Transarterial chemoembolization enhances programmed death 1 and programmed death-ligand 1 expression in hepatocellular carcinoma.

Ahmed Montasser, Aurélie Beaufrère, François Cauchy, Mohamed Bouattour, Olivier Soubrane, Miguel Albuquerque, Valérie Paradis.

   AIMS: Immunotherapies represent a new alternative therapeutic approach in hepatocellular carcinomas (HCC), with promising results when used in combination therapy. The aim of the study was to evaluate the potential of transarterial chemoembolization (TACE) to modulate PD-1 and PD-L1 expression profiles in a cohort of surgically treated HCC.
METHODS: A total of 82 surgically treated HCCs with (n=32) and without (n=50) preoperative TACE were included in the study. Immunohistochemical expression of PD-1 and PD-L1 was analyzed and compared according to TACE treatment. Pretreatment biopsies, available in 30 cases (20 with TACE and 10 without), were similarly analyzed. Follow-up data were retrieved from patients' charts.
RESULTS: Expression of PD-1 (≥1%) in intratumoral inflammatory cells (ICs) was observed in 46% of HCC while expressions of PD-L1(≥1%) in ICs and in tumor cells (TCs) were observed in 46% and 16%, respectively. A low expression of PD-1 (<1%) was associated with strong and diffuse glutamine synthetase overexpression (8% vs 27%, p=0.024). HCCs with TACE pretreatment showed significantly higher PD-L1 expression in TCs than those without TACE (2% vs 0.4%, p=0.027). Expression of PD-1 in ICs and PD-L1in both ICs and in TCs was higher in TACE-resected tumors than in corresponding pre-TACE biopsies (1.8% vs 8.1%, p=0.034, 0.8% vs 7.1%, p=0.032 and 0% vs 2.4%, p=0.043, respectively).
CONCLUSION: Our results, showing an increase in PD-1 and PD-L1 expression in HCC following TACE, support the use of TACE in combination with immunotherapy in selected cases to optimize tumor response.

Keywords:  Hepatocellular carcinoma; PD-1; PD-L1; immunotherapy; transarterial chemoembolization

DOI:  https://doi.org/10.1111/his.14317
Am J Transl Res. 2020 ;12(11): 7187-7198

Effects of intestinal trefoil factor on intestinal mucus barrier in burned mice.

Zi-En Wang, Jing Peng, Dan Wu, Jian-Jun Zheng, Xi Peng.

Severe burns might cause intense inflammatory response and tissue ischemia and hypoxia, and these effects result in intestinal mucosal barrier damage. In this study, we evaluated the effects of recombinant human intestinal trefoil factor (rhITF) on the intestinal mucus barrier after burn injury. The results showed that rhITF could improve the intestinal mucosal damage index, decrease diamine oxidase (DAO) activity, reduce intestinal damage, and thereby alleviate intestinal mucous permeability. Severe burns were associated with subsequent decreases in the mucus thickness and the levels of hexose, and mucin, and rhITF administration might partially reverse these changes. Additional experiments showed that supplementation with rhITF markedly increased the mitochondrial respiratory control rate (RCR) and phosphorus-oxygen ratio (P/O) in intestinal tissue. Moreover, rhITF improved the intestinal mucosal blood flow (IMBF) and the levels of oxygen extraction (Oext), nitric oxide (NO) and ATP. These results suggest that ITF can improve the blood perfusion of the intestinal mucosa after severe burns, promote the transport of glutamine in the intestinal mucosa, improve the energy metabolism of goblet cells, stimulate goblet cell differentiation and maturation, promote the synthesis and secretion of intestinal mucus, and maintain the barrier function of intestinal mucus.

Keywords: ITF; burn; intestine; mucus barrier
Data Brief. 2020 Dec;33 106591

Metabolomic and quality data for early and late passages of an antibody-producing industrial CHO cell line.

Steven W Sowa, Yueming Qian, Kathryn L Aron, Ping Xu, Erik Langsdorf, Bethanne Warrack, Nelly Aranibar, Gabi Tremml, Jianlin Xu, Duncan McVey, Michael Reily, Anurag Khetan, Michael C Borys, Zheng Jian Li.

  In this article, we provide four data sets for an industrial Chinese Hamster Ovary (CHO) cell line producing antibodies during a 14-day bioreactor run. This cell line was selected for further evaluation because of its significant titer loss as the cells were passaged over time. Four conditions that differed in cell bank ages were run for this dataset. Specifically, cells were passaged to passage 12, 21, 25, and 37 and then used in this experiment. Once the run commenced the following datasets were gathered: 1). Glycosylation data for each reactor 2). Size Exclusion Chromatography (SEC) data for the antibodies produced which allowed for the identification of high and low molecular weight species in the samples (N-Glycan and SEC data was taken on day 14 only). 3/4). Metabolites levels measured using Nuclear Magnetic Resonance (NMR) and liquid chromatography-mass spectroscopy (LC-MS) for all reactors over the time course of days 1, 4, 6, 8, 12, and 14. We also provide a graph of the glutamine levels for cells of different ages as an example of the utility of the data. These metabolomics data provide relative amounts for 36 metabolites (NMR) and 109 metabolites (LC-MS) over the 14-day time course. These data were collected in connection with a co-submitted paper [1].

Keywords:  Antibody Production; CHO cells; Cell aging; Genetic instability; Glycosylation; Metabolomics; Product quality

DOI:  https://doi.org/10.1016/j.dib.2020.106591