scholarly journals A non-canonical convergence of carbohydrate and glutamine metabolism is required after metabolic rewiring in 3D environment

2021 ◽  
Peng Wei ◽  
Alex J Bott ◽  
Ahmad A Cluntun ◽  
Jeffrey T Morgan ◽  
Corey N Cunningham ◽  

The fate of pyruvate, which is modulated mitochondrial pyruvate carrier (MPC) activity, is a defining metabolic feature in many cancers. Diffuse large B-cell lymphomas (DLBCLs) are a genetically and metabolically heterogenous cancer. Although MPC expression and activity differed between DLBCL subgroups, mitochondrial pyruvate oxidation was uniformly minimal. Mitochondrial pyruvate was instead robustly consumed by glutamate pyruvate transaminase 2 to support α-ketoglutarate production as part of glutamine catabolism. This led us to discover that glutamine exceeds pyruvate as a carbon source for the TCA cycle, but, MPC function is required to enable GPT2-mediated glutamine catabolism. Furthermore, we found that MPC inhibition only decreased DLBCL proliferation in a solid culture environment, but not in a suspension environment. Thus, the non-canonical connection between the consumption and assimilation of carbohydrates and glutamine in DLBCLs enables their proliferation in a solid 3D environment.

1994 ◽  
Vol 72 (3) ◽  
pp. 266-274 ◽  
S. E. Fleming ◽  
C. E. Kight

The influence of aging on glucose and glutamine metabolism by isolated jejunal cells was studied using young (4 months) and aged (24 months) Fischer 344 male rats when fed ad libitum or fasted 48 h. Concentration-dependent oxidation of glucose ([14C(U)]glucose) followed Michaelis–Menten kinetics. Neither Kox nor Vmax was influenced by animal age or feeding status, but at 1 mM, glucose oxidation was significantly higher for aged than young fed animals. In all animal groups, glutamine reduced glucose oxidation by ca. 60%, glucose stimulated glutamine oxidation by ca. 25%, and succinate CO2 ratios ranged from 1.37 for 20 mM glucose to 5.46 for 20 mM glucose + glutamine. The probability that a substrate that enters the TCA cycle will either remain in the cycle for one complete turn or leave and reenter as acetyl-CoA averaged 0.85 for glucose, 0.36 for glutamine, and 0.31 for glucose + glutamine. In comparison with the young fed animals, cells from fed aged animals showed lower oxygen uptake in the absence and presence of exogenous substrate, lower glucose oxidation, lower entry of glucose and glutamine into the TCA cycle, and lower contribution of glucose and glutamine carbon to anaplerosis and subsequent synthetic compounds. Differences between the young and aged animals were more pronounced in cells from fed animals than from fasted animals.Key words: glucose, glutamine, fasting, oxidation, anaplerosis.

2021 ◽  
Imadeddin Hijazi ◽  
Emily Wang ◽  
Michelle Orozco ◽  
Sarah Pelton ◽  
Amy Chang

Endoplasmic reticulum stress (ERS) occurs when cellular demand for protein folding exceeds the capacity of the organelle. Adaptation and cell survival in response to ERS requires a critical contribution by mitochondria and peroxisomes. During ERS response, mitochondrial respiration increases to ameliorate reactive oxygen species (ROS) accumulation; we now show in yeast that peroxisome abundance also increases to promote an adaptive response. In pox1▵ cells, defective in peroxisomal ß oxidation of fatty acids, respiratory response to ERS is impaired, and ROS accrues. However, respiratory response to ERS is rescued, and ROS production is mitigated in pox1▵ cells by overexpression of Mpc1, the mitochondrial pyruvate carrier that provides another source of acetyl CoA to fuel the TCA cycle and oxidative phosphorylation. Using proteomics, select mitochondrial proteins were identified that undergo upregulation by ERS to remodel respiratory machinery. Several peroxisome-based proteins were also increased, corroborating the peroxisomal role in ERS adaptation. Finally, ERS stimulates assembly of respiratory complexes into higher order supercomplexes, underlying increased electron transfer efficiency. Our results highlight peroxisomal and mitochondrial support for ERS adaptation to favor cell survival.

Cancers ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 68 ◽  
Simona Todisco ◽  
Paolo Convertini ◽  
Vito Iacobazzi ◽  
Vittoria Infantino

Hepatocellular carcinoma (HCC) is a common malignancy. Despite progress in treatment, HCC is still one of the most lethal cancers. Therefore, deepening molecular mechanisms underlying HCC pathogenesis and development is required to uncover new therapeutic strategies. Metabolic reprogramming is emerging as a critical player in promoting tumor survival and proliferation to sustain increased metabolic needs of cancer cells. Among the metabolic pathways, the tricarboxylic acid (TCA) cycle is a primary route for bioenergetic, biosynthetic, and redox balance requirements of cells. In recent years, a large amount of evidence has highlighted the relevance of the TCA cycle rewiring in a variety of cancers. Indeed, aberrant gene expression of several key enzymes and changes in levels of critical metabolites have been observed in many solid human tumors. In this review, we summarize the role of the TCA cycle rewiring in HCC by reporting gene expression and activity dysregulation of enzymes relating not only to the TCA cycle but also to glutamine metabolism, malate/aspartate, and citrate/pyruvate shuttles. Regarding the transcriptional regulation, we focus on the link between NF-κB-HIF1 transcriptional factors and TCA cycle reprogramming. Finally, the potential of metabolic targets for new HCC treatments has been explored.

2021 ◽  
Shawn K Milano ◽  
Qingqiu Huang ◽  
Thuy-Tien T Nguyen ◽  
Sekar Ramachandran ◽  
Aaron Finke ◽  

Many cancer cells become dependent on glutamine metabolism to compensate for glycolysis being uncoupled from the TCA cycle. The mitochondrial enzyme Glutaminase C (GAC) satisfies this "glutamine addiction" by catalyzing the first step in glutamine metabolism, making it an attractive drug target. Despite one of the allosteric inhibitors (CB-839) being in clinical trials, none of the drugs targeting GAC are approved for cancer treatment and their mechanism of action is not well understood. A major challenge has been the rational design of better drug candidates: standard cryo-cooled X-ray crystal structures of GAC bound to CB-839 and its analogs fail to explain their potency differences. Here, we address this problem by using an emerging technique, serial room temperature crystallography, which enabled us to observe clear differences between the binding conformations of inhibitors with significantly different potencies. A computational model was developed to further elucidate the molecular basis of inhibitor potency. We then corroborated the results from our modeling efforts by using recently established fluorescence assays that directly read-out inhibitor binding to GAC. Together, these findings provide new insights into the mechanisms used by a major class of allosteric GAC inhibitors and for the future rational design of more potent drug candidates.

2021 ◽  
Linyu Ran ◽  
Song Zhang ◽  
Pei Zhao ◽  
Jiaqi Zhou ◽  
Haiyun Gan ◽  

Abstract Glycolysis is essential for the classical activation of macrophages (M1), but how glycolytic pathway metabolites engage in this process remains to be elucidated. Glycolysis culminates in the production of pyruvate, which can be transported into the mitochondria by the mitochondrial pyruvate carrier (MPC) followed by conversion to citrate and utilization in the TCA cycle. Alternatively, pyruvate can be metabolized to lactate under aerobic conditions, which had been considered to be the dominant route in the setting of classical macrophage activation. However, based on studies that used UK5099 as a MPC inhibitor and showed reduction in key inflammatory cytokines, the mitochondrial route has been considered to be of significance for M1 activation as well. Herein, using a genetic depletion model, we found that MPC is dispensable for metabolic reprogramming and the activation of M1. While UK5099 reaches maximal MPC inhibitory capacity at approximately 2–5µM, higher concentrations are required to inhibit inflammatory cytokine production in M1 and this is independent of MPC expression. Apart from MPC inhibition, UK5099 at high doses impairs glutamate oxidation, mitochondrial membrane potential and HIF-1α stabilization. Taken together, UK5099 inhibits inflammatory responses in M1 macrophages due to effects other than MPC inhibition.

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 25-26
Lingzhi Li ◽  
Changying Jiang ◽  
Lucy Jayne Navsaria ◽  
Yang Liu ◽  
Angela Leeming ◽  

Background: Mantle cell lymphoma (MCL) is an incurable B cell non-Hodgkin's lymphoma characterized by high refractory occurrence following drug treatment. Despite the encouraging initial MCL tumor response to ibrutinib (IBN), relapse occurs only after few months of treatment due to multiple resistance mechanisms. Thus, the novel therapeutic strategies targeting resistant mechanisms are crucial. Our group has recently shown that among the highly proliferative MCL population, a subpopulation of IBN-R cells exhibits increased OXPHOS activity that is fueled by increased glutaminolysis and rely more on mitochondrial respiration for their grow and survival. The aim of this work was to uncover potential targets responsible for the upregulation of OXPHOS pathway in the refractory/relapsed (R/R) MCL by using multiple biochemical and biological strategies. We focused the present study on glutaminase (GLS), the enzyme that converts glutamine to glutamate, a precursor of α-ketoglutarate (α-KG) that links glutamate to the TCA cycle. Incorporation of α-KG into the TCA cycle is a major anaplerotic step in proliferating cells and is critical for the maintenance of TCA cycle function. To further demonstrate the reliance of OXPHOS on glutamine anaplerosis, we have further tested the combinatory effects of targeting GLS and OXPHOS using their respective inhibitors, CB-839 and IACS-010759, on tumor killing activity in R/R MCL. Methods:Primary MCL cells from patient leukapheresis or whole blood specimens, as well as established MCL cell lines were used as experimental models of MCL. Metabolomic profiling was used to determine intracellular metabolite fluxes and levels. Cell Titer Glo assay was used to measure cell proliferation/viability after treatment with inhibitors. Annexin V and propidium iodide were used to measure cell apoptosis and cell cycle arrestviaflow cytometry analysis. Magnetic microbeads-based B-cell isolation method were used for the purification of malignant B cells from patient samples. Western blot analysis was used to evaluate protein level expression. Patient-derived Xenograft (PDX) mouse model created from patients with MCL was used to evaluate the in vivo anti-tumor activity and potential clinical value of GLS and OXPHOS inhibitors. Results:Our recent metabolomic profiling studies have demonstrated that glutaminolysis and OXPHOS are upregulated in IBN-R MCL, manifested by increased glutamine uptake in the ibrutinib-resistant MCL cell lines (p=0.03).Inhibition of glutamine metabolism with the allosteric GLS1-selective inhibitor BPTES resulted in inhibition of cell viability (0.2381uM-9.98uM), indicating that MCL cells are dependent on glutamine metabolism for their proliferation. To corroborate with the above finding, we also presented evidence that GLS1 is highly increased in IBN-R and CART-R MCL patient samples and cell lines confirmed by immunoblotting. Inhibiting of GLS would lead to significant reduction in OXPHOS, mitochondria membrane potential and ATP production, as either single drug or in combination with other targeting agents. To identify a clinical actionable GLS inhibitor for the treatment of MCL, we chose a GLS1 specific inhibitor CB-839 (Selleckchem), currently under several phase II and III clinical trials investigation on solid tumors. Inhibiting GLS1 with CB-839 leads to the decreased cell viability in MCL (0.5626nM-308.4nM). Of note, the treatment with CB-839 to MCL cell lines induces S phase reduction in both Jeko-1 (17.23%) and Z-138 (14.01%), as well as induces significant apoptosis (p=0.013 and p=0.002 in Jeko-1 and Z-138 cells). GLS inhibition will be further explored in the context of mitochondria defect or hypoxia, where OXPHOS maybe deficient. Importantly, while CB-839 is continuing its validation in several solid tumor models, this is the first study providing data on its efficacy in preclinical models of MCL. Conclusion:In conclusion, we report that glutaminolysis and OXPHOS are upregulated in IBN-R MCL that could be partially due to high expression of GLS1. Our preliminary results revealed that the new GLS inhibitor, GCB-839, may present a clinical potential for a new indication and warrants more in-depth investigation. Deciphering the mechanisms involved in MCL metabolic heterogeneity and adaptability during drug resistance development would be crucial to identify key actors enabling MCL cells to escape from therapy. Disclosures Wang: Acerta Pharma:Research Funding;Molecular Templates:Research Funding;InnoCare:Consultancy;Oncternal:Consultancy, Research Funding;Celgene:Consultancy, Other: Travel, accommodation, expenses, Research Funding;Targeted Oncology:Honoraria;MoreHealth:Consultancy;Kite Pharma:Consultancy, Other: Travel, accommodation, expenses, Research Funding;Lu Daopei Medical Group:Honoraria;OMI:Honoraria, Other: Travel, accommodation, expenses;Verastem:Research Funding;Nobel Insights:Consultancy;BioInvent:Research Funding;Guidepoint Global:Consultancy;AstraZeneca:Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding;Pharmacyclics:Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding;Janssen:Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding;Juno:Consultancy, Research Funding;Dava Oncology:Honoraria;Loxo Oncology:Consultancy, Research Funding;Pulse Biosciences:Consultancy;OncLive:Honoraria;Beijing Medical Award Foundation:Honoraria;VelosBio:Research Funding.

2019 ◽  
Vol 9 (1) ◽  
Yiqing Zhao ◽  
Xuan Zhao ◽  
Vanessa Chen ◽  
Ying Feng ◽  
Lan Wang ◽  

AbstractCancer cells in culture rely on glutamine as an anaplerotic substrate to replenish tricarboxylic acid (TCA) cycle intermediates that have been consumed. but it is uncertain whether cancers in vivo depend on glutamine for anaplerosis. Here, following in vivo infusions of [13C5]-glutamine in mice bearing subcutaneous colon cancer xenografts, we showed substantial amounts of infused [13C5]-glutamine enters the TCA cycle in the tumors. Consistent with our prior observation that colorectal cancers (CRCs) with oncogenic mutations in the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic (PIK3CA) subunit are more dependent on glutamine than CRCs with wild type PIK3CA, labeling from glutamine to most TCA cycle intermediates was higher in PIK3CA-mutant subcutaneous xenograft tumors than in wild type PIK3CA tumors. Moreover, using orthotopic mouse colon tumors estalished from human CRC cells or patient-derived xenografts, we demonstrated substantial amounts of infused [13C5]-glutamine enters the TCA cycle in the tumors and tumors utilize anaplerotic glutamine to a greater extent than adjacent normal colon tissues. Similar results were seen in spontaneous colon tumors arising in genetically engineered mice. Our studies provide compelling evidence CRCs utilizes glutamine to replenish the TCA cycle in vivo, suggesting that targeting glutamine metabolism could be a therapeutic approach for CRCs, especially for PIK3CA-mutant CRCs.

2021 ◽  
Xuyen H. Le ◽  
Chun-Pong Lee ◽  
A. Harvey Millar

AbstractMalate oxidation by plant mitochondria enables the generation of both oxaloacetate (OAA) and pyruvate for tricarboxylic acid (TCA) cycle function, potentially eliminating the need for pyruvate transport into mitochondria in plants. Here we show that the absence of the mitochondrial pyruvate carrier 1 (MPC1) causes the co-commitment loss of its orthologs, MPC3/MPC4, and eliminates pyruvate transport into Arabidopsis mitochondria, proving it is essential for MPC complex function. While the loss of either MPC or mitochondrial pyruvate-generating NAD-malic enzyme (NAD-ME) did not cause vegetative phenotypes, the lack of both reduced plant growth and caused an increase in cellular pyruvate levels, indicating a block in respiratory metabolism, and elevated the levels of branched-chain amino acids at night, a sign of alterative substrate provision for respiration. 13C-pyruvate feeding of leaves lacking MPC showed metabolic homeostasis were largely maintained except for alanine and glutamate, indicating that transamination contributes to restoration of the metabolic network to an operating equilibrium by delivering pyruvate independently of MPC into the matrix. Inhibition of alanine aminotransferases (AlaAT) when MPC1 is absent resulted in extremely retarded phenotypes in Arabidopsis, suggesting all pyruvate-supplying enzymes work synergistically to support the TCA cycle for sustained plant growth.

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. SCI-27-SCI-27
Chi Van Dang

Abstract Abstract SCI-27 The MYC oncogene plays a pivotal role in human lymphoid neoplasias, specifically in lymphomas and acute leukemias, which are characterized by altered glucose metabolism, termed the Warburg effect. The Warburg effect or elevated conversion glucose to lactate by cancer cells has been a prevailing model of cancer metabolism. Since the 1980’s, genetic alterations of oncogenes and tumor suppressors have provided insights into tumorigenesis. However, whether metabolism contributes to tumorigenesis was highly debated. In 1997, we reported that the MYC oncogene product, the Myc transcription factor, regulates the lactate dehydrogenase A (LDHA)gene. Myc also activates many glycolytic enzymes, mitochondrial biogenesis, and glutamine metabolism by inducing glutaminase (GLS) and glutamine transporters, thereby providing not only ATP through the TCA cycle but also anapleurotic building blocks. Myc also induces biomass accumulation by stimulating ribosomal biogenesis. It stimulates the cell cycle machinery and DNA replication. Deregulated MYC in cancer results in enforced biomass accumulation, such that cell death occurs when bioenergetic demands exceed nutrient availability. In this regard, we have exploited this conceptual framework and targeted LDHA and GLS with small molecular inhibitors as proof-of- concept that altered cancer metabolism could be targeted for cancer therapy. Specifically, we documented that a drug-like inhibitor of LDHA could decreased tumor xenograft growth, providing evidence that metabolic therapy is feasible. We further found in a human Burkitt lymphoma model that Myc induces a genetic program that drives glutamine metabolism both under aerobic and hypoxic conditions. Inhibition of glutaminase, which converts glutamine to glutamate for its catabolism by the TCA cycle, by a drug-like molecule also diminished lymphoma xenograft growth in vivo. These studies indicate that targeting cancer cell metabolism could constitute a novel strategy to treat lymphoid neoplasias. Disclosures: Dang: Agios Pharmaceuticals, Inc.: Consultancy, Honoraria.

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