bims-glucam Biomed News
on Glutamine cancer metabolism
Issue of 2021‒05‒23
fourteen papers selected by
Sreeparna Banerjee
Middle East Technical University

  1. Adv Exp Med Biol. 2021 ;1311 17-38
      Metabolism is a fundamental process for all cellular functions. For decades, there has been growing evidence of a relationship between metabolism and malignant cell proliferation. Unlike normal differentiated cells, cancer cells have reprogrammed metabolism in order to fulfill their energy requirements. These cells display crucial modifications in many metabolic pathways, such as glycolysis and glutaminolysis, which include the tricarboxylic acid (TCA) cycle, the electron transport chain (ETC), and the pentose phosphate pathway (PPP) [1]. Since the discovery of the Warburg effect, it has been shown that the metabolism of cancer cells plays a critical role in cancer survival and growth. More recent research suggests that the involvement of glutamine in cancer metabolism is more significant than previously thought. Glutamine, a nonessential amino acid with both amine and amide functional groups, is the most abundant amino acid circulating in the bloodstream [2]. This chapter discusses the characteristic features of glutamine metabolism in cancers and the therapeutic options to target glutamine metabolism for cancer treatment.
    Keywords:  Glutamine addiction; Glutamine metabolism; Targeting amino acid synthesis; Targeting glutamine metabolism; Transaminase upregulation
  2. Mol Oncol. 2021 May 18.
      Oncogenic KRAS mutations develop unique metabolic dependencies on nutrients to support tumor metabolism and cell proliferation. In particular, KRAS mutant cancer cells exploit amino acids (AAs) such as glutamine and leucine, to accelerate energy metabolism, redox balance through glutathione (GSH) synthesis and macromolecule biosynthesis. However, the identities of the amino acid transporters (AATs) that are prominently upregulated in KRAS mutant cancer cells, and the mechanism regulating their expression have not yet been systematically investigated. Here we report that the majority of the KRAS mutant colorectal cancer (CRC) cells upregulate selected AATs (SLC7A5/LAT1, SLC38A2/SNAT2 and SLC1A5/ASCT2), which correlates with enhanced uptake of AAs such as glutamine and leucine. Consistently, knockdown of oncogenic KRAS downregulated the expression of AATs, thereby decreasing the levels of amino acids taken up by CRC cells. Moreover, overexpression of mutant KRAS upregulated the expression of AATs (SLC7A5/LAT1, SLC38A2/SNAT2 and SLC1A5/ASCT2) in KRAS wild-type CRC cells and mouse embryonic fibroblasts (MEFs). In addition, we show that the YAP1 (Yes-associated protein 1) transcriptional coactivator accounts for increased expression of AATs and mTOR activation in KRAS mutant CRC cells. Specific knockdown of AATs by shRNAs or pharmacological blockage of AATs effectively inhibited AA uptake, mTOR activation and cell proliferation. Collectively, we conclude that oncogenic KRAS mutations enhance the expression of AATs via the hippo effector YAP1, leading to mTOR activation and CRC cell proliferation.
    Keywords:  Amino acid transporters; Oncogene; SLC1A5/ASCT2; SLC38A2/SNAT2; SLC7A5/LAT1; Solute carriers
  3. Mol Cell. 2021 May 08. pii: S1097-2765(21)00269-0. [Epub ahead of print]
      Glutaminase regulates glutaminolysis to promote cancer cell proliferation. However, the mechanism underlying glutaminase activity regulation is largely unknown. Here, we demonstrate that kidney-type glutaminase (GLS) is highly expressed in human pancreatic ductal adenocarcinoma (PDAC) specimens with correspondingly upregulated glutamine dependence for PDAC cell proliferation. Upon oxidative stress, the succinyl-coenzyme A (CoA) synthetase ADP-forming subunit β (SUCLA2) phosphorylated by p38 mitogen-activated protein kinase (MAPK) at S79 dissociates from GLS, resulting in enhanced GLS K311 succinylation, oligomerization, and activity. Activated GLS increases glutaminolysis and the production of nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione, thereby counteracting oxidative stress and promoting tumor cell survival and tumor growth in mice. In addition, the levels of SUCLA2 pS79 and GLS K311 succinylation, which were mutually correlated, were positively associated with advanced stages of PDAC and poor prognosis for patients. Our findings reveal critical regulation of GLS by SUCLA2-coupled GLS succinylation regulation and underscore the regulatory role of metabolites in glutaminolysis and PDAC development.
    Keywords:  GLS; GSH; NADPH; SUCLA2; glutaminolysis; p38; phosphorylation; succinyl-CoA; succinylation; tumorigenesis
  4. J Cell Sci. 2020 Jan 01. pii: jcs.251645. [Epub ahead of print]
      Osteoblasts are the principal bone forming cells. As such, osteoblasts have enhanced demand for amino acids to sustain high rates of matrix synthesis associated with bone formation. The precise systems utilized by osteoblasts to meet these synthetic demands are not well understood. WNT signaling is known to rapidly stimulate glutamine uptake during osteoblast differentiation. Using a cell biology approach, we identified two amino acid transporters, Slc7a7 and Slc1a5, as the primary transporters of glutamine in response to WNT. Slc1a5 mediates the majority of glutamine uptake, whereas Slc7a7 mediates the rapid increase in glutamine uptake in response to WNT. Mechanistically, WNT signals through the canonical/β-catenin dependent pathway to rapidly induce Slc7a7 expression. Conversely, Slc1a5 expression is regulated by the transcription factor ATF4 downstream of the mTORC1 pathway. Targeting either Slc1a5 or Slc7a7 using shRNA reduced WNT induced glutamine uptake and prevented osteoblast differentiation. Collectively these data highlight the critical nature of glutamine transport for WNT induced osteoblast differentiation.
    Keywords:  Glutamine; Osteoblast; Slc1a5; Slc7a7; WNT; β-catenin
  5. Dis Model Mech. 2020 Jan 01. pii: dmm.047134. [Epub ahead of print]
      Astrocyte dysfunction is a primary factor in hepatic encephalopathy (HE) impairing neuronal activity under hyperammonemia. In particular the early events causing ammonia-induced toxicity to astrocytes are not well understood. Using established cellular HE models, we show that mitochondria rapidly undergo fragmentation in a reversible manner upon hyperammonemia. Further, within a timescale of minutes mitochondrial respiration and glycolysis were hampered which occurred in a pH-independent manner. Using metabolomics an accumulation of numerous amino acids, including branched chain amino acids and glucose was observed. Metabolomic tracking of 15N-labeled ammonia showed rapid incorporation of 15N into glutamate and glutamate-derived amino acids. Downregulating human GLUD2, encoding mitochondrial glutamate dehydrogenase 2 (GDH2), inhibiting GDH2 activity by SIRT4 overexpression, and supplementing cells with glutamate or glutamine alleviated ammonia-induced inhibition of mitochondrial respiration. Metabolomic tracking of 13C-glutamine showed that hyperammonemia can inhibit anaplerosis of TCA-cycle intermediates. Contrary to its classical anaplerotic role, we show that under hyperammonemia GDH2 rather catalyzes the removal of ammonia by reductive amination of α-ketoglutarate which efficiently and rapidly inhibits the TCA-cycle. Overall, we propose a critical GDH2-dependent mechanism in HE models that on the one hand helps to remove ammonia but on the other hand impairs energy metabolism in mitochondria rapidly.
    Keywords:  Brain energy metabolism; Glutamate dehydrogenase; Hepatic encephalopathy; Hyperammonemia; Mitochondria; TCA-cycle
  6. Adv Exp Med Biol. 2021 ;1311 229-248
      Despite the many recent breakthroughs in cancer research, oncology has traditionally been seen as a distinct field from other diseases. Recently, more attention has been paid to repurposing established therapeutic strategies and targets of other diseases towards cancer treatment, with some of these attempts generating promising outcomes [1, 2]. Recent studies using advanced metabolomics technologies [3] have shown evidence of close metabolic similarities between cancer and neurological diseases. These studies have unveiled several metabolic characteristics shared by these two categories of diseases, including metabolism of glutamine, gamma-aminobutyric acid (GABA), and N-acetyl-aspartyl-glutamate (NAAG) [4-6]. The striking metabolic overlap between cancer and neurological diseases sheds light on novel therapeutic strategies for cancer treatment. For example, 2-(phosphonomethyl) pentanedioic acid (2-PMPA), one of the glutamate carboxypeptidase II (GCP II) inhibitors that prevent the conversion of NAAG to glutamate, has been shown to suppress cancer growth [6, 7]. These promising results have led to an increased interest in integrating this metabolic overlap between cancer and neurological diseases into the study of cancer metabolism. The advantages of studying this metabolic overlap include not only drug repurposing but also translating existing knowledge from neurological diseases to the field of cancer research. This chapter discusses the specific overlapping metabolic features between cancer and neurological diseases, focusing on glutamine, GABA, and NAAG metabolisms. Understanding the interconnections between cancer and neurological diseases will guide researchers and clinicians to find more effective cancer treatments.
    Keywords:  Cancer; GABA; GCP II; Glutamate; Glutamine; NAAG; Neurological diseases
  7. Adv Exp Med Biol. 2021 ;1311 77-88
      Currently, approximately 95% of pancreatic cancers are pancreatic ductal adenocarcinomas (PDAC), which are the most aggressive form and the fourth leading cause of cancer death with extremely poor prognosis [1]. Poor prognosis is primarily attributed to the late diagnosis of the disease when patients are no longer candidates for surgical resection [2]. Cancer cells are dependent on the oncogenes that allow them to proliferate limitlessly. Thus, targeting the expression of known oncogenes in pancreatic cancer has been shown to lead to more effective treatment [3]. This chapter discusses the complexity of metabolic features in pancreatic cancers. In order to comprehend the heterogeneous nature of cancer metabolism fully, we need to take into account the close relationship between cancer metabolism and genetics. Gene expression varies tremendously, not only among different types of cancers but also within the same type of cancer among different patients. Cancer metabolism heterogeneity is often prompted and perpetuated not only by mutations in oncogenes and tumor-suppressor genes but also by the innate diversity of the tumor microenvironment. Much effort has been focused on elucidating the genetic alterations that correlate with disease progression and treatment response [4, 5]. However, the precise mechanisms by which tumor metabolism contributes to cancer growth, survival, mobility, and aggressiveness represent a functional readout of tumor progression (Fig. 1).
    Keywords:  Combined therapy; Glucose metabolism; Glutamine metabolism; KRAS mutation; Pancreatic ductal adenocarcinoma
  8. Trends Cancer. 2021 May 18. pii: S2405-8033(21)00083-2. [Epub ahead of print]
      Glutamine metabolism is reprogrammed during tumorigenesis and has been investigated as a promising target for cancer therapy. However, efforts to drug this process are confounded by the intrinsic metabolic heterogeneity and flexibility of tumors, as well as the risk of adverse effects on the anticancer immune response. Recent research has yielded important insights into the mechanisms that determine the tumor and the host immune responses to pharmacological perturbation of glutamine metabolism. Here, we discuss these findings and suggest that, collectively, they point toward patient stratification and drug combination strategies to maximize the efficacy of glutamine metabolism inhibitors as cancer therapeutics.
    Keywords:  CB-839; JHU083; cancer metabolism; glutaminase; glutamine; immunometabolism
  9. Adv Exp Med Biol. 2021 ;1311 117-126
      According to data from the American Cancer Society, cancer is one of the deadliest health problems globally. Annually, renal cell carcinoma (RCC) causes more than 100,000 deaths worldwide [1-4], posing an urgent need to develop effective treatments to increase patient survival outcomes. New therapies are expected to address a major factor contributing to cancer's resistance to standard therapies: oncogenic heterogeneity. Gene expression can vary tremendously among different types of cancers, different patients of the same tumor type, and even within individual tumors; various metabolic phenotypes can emerge, making singletherapy approaches insufficient. Novel strategies targeting the diverse metabolism of cancers aim to overcome this obstacle. Though some have yielded positive results, it remains a challenge to uncover all of the distinct metabolic profiles of RCC. In the quest to overcome this obstacle, the metabolic oriented research focusing on these cancers has offered freshly new perspectives, which are expected to contribute heavily to the development of new treatments.
    Keywords:  Glucose metabolism; Glutamine metabolism; Metabolic phenotypes; Oncogenic heterogeneity—intratumoral heterogeneity; Renal cell carcinoma
  10. Adv Exp Med Biol. 2021 ;1311 249-263
      According to data from the World Health Organization, cardiovascular diseases and cancer are the two leading causes of mortality in the world [1]. Despite the immense effort to study these diseases and the constant innovation in treatment modalities, the number of deaths associated with cardiovascular diseases and cancer is predicted to increase in the coming decades [1]. From 2008 to 2030, due to population growth and population aging in many parts of the world, the number of deaths caused by cancer globally is projected to increase by 45%, corresponding to an annual increase of around four million people [1]. For cardiovascular diseases, this number is six million people [1]. In the United States, treatments for these two diseases are among the most costly and result in a disproportionate impact on low- and middleincome people. As the fight against these fatal diseases continues, it is crucial that we continue our investigation and broaden our understanding of cancer and cardiovascular diseases to innovate our prognostic and treatment approaches. Even though cardiovascular diseases and cancer are usually studied independently [2-12], there are some striking overlaps between their metabolic behaviors and therapeutic targets, suggesting the potential application of cardiovascular disease treatments for cancer therapy. More specifically, both cancer and many cardiovascular diseases have an upregulated glutaminolysis pathway, resulting in low glutamine and high glutamate circulating levels. Similar treatment modalities, such as glutaminase (GLS) inhibition and glutamine supplementation, have been identified to target glutamine metabolism in both cancer and some cardiovascular diseases. Studies have also found similarities in lipid metabolism, specifically fatty acid oxidation (FAO) and synthesis. Pharmacological inhibition of FAO and fatty acid synthesis have proven effective against many cancer types as well as specific cardiovascular conditions. Many of these treatments have been tested in clinical trials, and some have been medically prescribed to patients to treat certain diseases, such as angina pectoris [13, 14]. Other metabolic pathways, such as tryptophan catabolism and pyruvate metabolism, were also dysregulated in both diseases, making them promising treatment targets. Understanding the overlapping traits exhibited by both cancer metabolism and cardiovascular disease metabolism can give us a more holistic view of how important metabolic dysregulation is in the progression of diseases. Using established links between these illnesses, researchers can take advantage of the discoveries from one field and potentially apply them to the other. In this chapter, we highlight some promising therapeutic discoveries that can support our fight against cancer, based on common metabolic traits displayed in both cancer and cardiovascular diseases.
    Keywords:  Cancer; Cardiovascular diseases; Fatty acid oxidation; Glutamine metabolism; Pyruvate dehydrogenase complex; Tryptophan catabolism
  11. Methods Mol Biol. 2021 ;2318 231-239
      The MYC gene regulates normal cell growth and is deregulated in many human cancers, contributing to tumor growth and progression. The MYC transcription factor activates RNA polymerases I, II, and III target genes that are considered housekeeping genes. These target genes are largely involved in ribosome biogenesis, fatty acid, protein and nucleotide synthesis, nutrient influx or metabolic waste efflux, glycolysis, and glutamine metabolism. MYC's function as a driver of cell growth has been revealed through RNA sequencing, genome-wide chromatin immunoprecipitation, proteomics, and importantly metabolomics, which is highlighted in this chapter.
    Keywords:  Cancer metabolism; MYC; Mass spectrometry; Metabolomics; Transcription
  12. J Cell Sci. 2020 Jan 01. pii: jcs.236661. [Epub ahead of print]
      Epithelial cells such as liver-resident hepatocytes rely heavily on the Rab family of small GTPases to perform membrane trafficking events that dictate cell physiology and metabolism. Not surprisingly, disruption of several Rabs can manifest in metabolic diseases or cancer. Rab32 is expressed in many secretory epithelial cells but its role in cellular metabolism is virtually unknown. In this study, we find that Rab32 associates with lysosomes and regulates proliferation and cell size of Hep3B hepatoma and HeLa cells. Specifically, we identify that Rab32 supports mTORC1 signaling under basal and amino acid stimulated conditions. Consistent with inhibited mTORC1, an increase in nuclear TFEB localization and lysosome biogenesis is also observed in Rab32-depleted cells. Finally, we find that Rab32 interacts with mTOR kinase and that loss of Rab32 reduces the association of mTOR and mTORC1 pathway proteins with lysosomes, suggesting that Rab32 regulates lysosomal mTOR trafficking. In summary, these findings suggest that Rab32 functions as a novel regulator of cellular metabolism through supporting mTORC1 signaling.
    Keywords:  Lysosome; MTORC1; S6K; Small Rab GTPase; TFEB
  13. J Cell Sci. 2020 Jan 01. pii: jcs.239277. [Epub ahead of print]
      Oncogenes can create metabolic vulnerabilities in cancer cells. We tested how AKT and MYC affect the ability of cells to shift between respiration and glycolysis. Using immortalized mammary epithelial cells, we discovered that constitutively active AKT but not MYC induced cell death in galactose culture, where cells rely on oxidative phosphorylation for energy generation. However, the negative effects of AKT were temporary, and AKT-expressing cells recommenced growth after ∼15 days in galactose. To identify the mechanisms regulating AKT-mediated cell death, we used metabolomics and found that AKT cells dying in galactose upregulated glutathione metabolism. Proteomic profiling revealed that AKT cells dying in galactose also upregulated nonsense-mediated mRNA decay, a marker of sensitivity to oxidative stress. We therefore measured levels of reactive oxygen species (ROS) and discovered that galactose induced ROS exclusively in cells expressing AKT. Furthermore, ROS were required for galactose-induced death of AKT-expressing cells. We then confirmed that galactose induced ROS-mediated cell death in breast cancer cells with upregulated AKT signaling. These results demonstrate that AKT but not MYC restricts the flexibility of cancer cells to use oxidative phosphorylation.
    Keywords:  MYC; Metabolomics; Oncogene; PI3K/AKT signaling; Proteomics; Reactive Oxygen Species
  14. Cell Death Dis. 2021 May 19. 12(6): 511
      MYCN amplification is tightly associated with the poor prognosis of pediatric neuroblastoma (NB). The regulation of NB cell death by MYCN represents an important aspect, as it directly contributes to tumor progression and therapeutic resistance. However, the relationship between MYCN and cell death remains elusive. Ferroptosis is a newly identified cell death mode featured by lipid peroxide accumulation that can be attenuated by GPX4, yet whether and how MYCN regulates ferroptosis are not fully understood. Here, we report that MYCN-amplified NB cells are sensitive to GPX4-targeting ferroptosis inducers. Mechanically, MYCN expression reprograms the cellular iron metabolism by upregulating the expression of TFRC, which encodes transferrin receptor 1 as a key iron transporter on the cell membrane. Further, the increased iron uptake promotes the accumulation of labile iron pool, leading to enhanced lipid peroxide production. Consistently, TFRC overexpression in NB cells also induces selective sensitivity to GPX4 inhibition and ferroptosis. Moreover, we found that MYCN fails to alter the general lipid metabolism and the amount of cystine imported by System Xc(-) for glutathione synthesis, both of which contribute to ferroptosis in alternative contexts. In conclusion, NB cells harboring MYCN amplification are prone to undergo ferroptosis conferred by TFRC upregulation, suggesting that GPX4-targeting ferroptosis inducers or TFRC agonists can be potential strategies in treating MYCN-amplified NB.