bims-glucam Biomed News
on Glutamine cancer metabolism
Issue of 2021‒03‒21
fifteen papers selected by
Sreeparna Banerjee
Middle East Technical University

  1. Onco Targets Ther. 2021 ;14 1807-1819
      Background: Circular RNA (circRNA) is a key regulator of cancer, and it has been proved to be involved in the regulation of cancer progression including non-small cell lung cancer (NSCLC). Circ-PITX1 was found to be a significantly upregulated circRNA in NSCLC, and its role and potential mechanism in NSCLC progression deserve further investigation.Methods: The expression levels of circ-PITX1, microRNA (miR)-1248 and cyclin D2 (CCND2) were examined by quantitative real-time PCR (qRT-PCR). Cell proliferation, apoptosis, cell cycle process, migration and invasion were determined using cell counting kit 8 (CCK8) assay, colony formation assay, flow cytometry, wound healing assay and transwell assay. Xenograft models were built to explore the role of circ-PITX1 in NSCLC tumor growth in vivo. The glycolysis and glutamine metabolism of cells were assessed by detecting the consumptions of glucose and glutamine, cell extracellular acidification rate (ECAR), and the productions of lactate, α-ketoglutaric acid (α-KG) and ATP. The protein levels of hexokinase 2 (HK-2), glutaminase 1 (GLS1) and CCND2 were tested by Western blot (WB) analysis. Dual-luciferase reporter assay and RIP assay were employed to verify the interaction between miR-1248 and circ-PITX1 or CCND2.
    Results: Circ-PITX1 was upregulated in NSCLC and its silencing could inhibit the proliferation, migration, invasion, cell cycle process, glycolysis, glutamine metabolism, and promote the apoptosis of NSCLC cells in vitro, as well as reduced tumor growth in vivo. In the terms of mechanism, we found that circ-PITX1 could act as a sponge of miR-1248, and miR-1248 could target CCND2. In addition, miR-1248 inhibitor reversed the inhibitory effect of circ-PITX1 knockdown on NSCLC progression. Similarly, CCND2 overexpression also reversed the suppressive effect of miR-1248 on NSCLC progression. Moreover, circ-PITX1 positively regulated CCND2 expression by sponging miR-1248.
    Conclusion: Circ-PITX1 served as a sponge of miR-1248 to promote NSCLC progression by upregulating CCND2.
    Keywords:  CCND2; circ-PITX1; miR-1248; non-small cell lung cancer
  2. Biochim Biophys Acta Bioenerg. 2021 Mar 12. pii: S0005-2728(21)00043-8. [Epub ahead of print] 148410
      In post-mitotic cells, mitochondrial ATP/ADP exchange occurs by the adenine nucleotide translocator (ANT). Driven by membrane potential (ΔΨ), ANT catalyzes electrogenic exchange of ATP4- for ADP3-, leading to higher ATP/ADP ratios in the cytosol than mitochondria. In cancer cells, ATP/ADP exchange occurs not by ANT but likely via the non-electrogenic ATP-Mg/phosphate carrier. Consequences of non-electrogenic exchange are: 1) Cytosolic ATP/ADP decreases to stimulate aerobic glycolysis. 2) Without proton utilization for exchange, ATP/O increases by 35% for complete glucose oxidation. 3) Decreased cytosolic ATP/ADP•Pi increases NAD(P)H/NAD(P)+. Increased NADH increases lactate/pyruvate, and increased NADPH promotes anabolic metabolism. Fourth, increased mitochondrial NADH/NAD+ magnifies the redox span across Complexes I and III, which increases ΔΨ, reactive oxygen species generation, and susceptibility to ferroptosis. 5) Increased mitochondrial NADPH/NADP+ favors a reverse isocitrate dehydrogenase-2 reaction with citrate accumulation and export for biomass formation. Consequently, 2-oxoglutarate formation occurs largely via oxidation of glutamine, the preferred respiratory substrate of cancer cells. Overall, non-electrogenic ATP/ADP exchange promotes aerobic glycolysis (Warburg effect) and confers growth advantages to cancer cells.
    Keywords:  ATP/ADP exchange; Aerobic glycolysis; Cancer; Glutamine; Mitochondria; Warburg effect
  3. Curr Opin Chem Biol. 2021 Mar 12. pii: S1367-5931(21)00006-5. [Epub ahead of print]62 64-81
      Targeting glutamine catabolism has been attracting more research attention on the development of successful cancer therapy. Catalytic enzymes such as glutaminase (GLS) in glutaminolysis, a series of biochemical reactions by which glutamine is converted to glutamate and then alpha-ketoglutarate, an intermediate of the tricarboxylic acid (TCA) cycle, can be targeted by small molecule inhibitors, some of which are undergoing early phase clinical trials and exhibiting promising safety profiles. However, resistance to glutaminolysis targeting treatments has been observed, necessitating the development of treatments to combat this resistance. One option is to use synergy drug combinations, which improve tumor chemotherapy's effectiveness and diminish drug resistance and side effects. This review will focus on studies involving the glutaminolysis pathway and diverse combination therapies with therapeutic implications.
    Keywords:  Combination therapy; Glutaminase; Glutaminolysis; Metabolic reprogramming; Therapeutic resistance
  4. Cell Death Dis. 2021 Mar 17. 12(4): 283
      Inhibition of the eukaryotic initiation factor 5A activation by the spermidine analogue GC7 has been shown to protect proximal cells and whole kidneys against an acute episode of ischaemia. The highlighted mechanism involves a metabolic switch from oxidative phosphorylation toward glycolysis allowing cells to be transiently independent of oxygen supply. Here we show that GC7 decreases protein expression of the renal GLUT1 glucose transporter leading to a decrease in transcellular glucose flux. At the same time, GC7 modifies the native energy source of the proximal cells from glutamine toward glucose use. Thus, GC7 acutely and reversibly reprogrammes function and metabolism of kidney cells to make glucose its single substrate, and thus allowing cells to be oxygen independent through anaerobic glycolysis. The physiological consequences are an increase in the renal excretion of glucose and lactate reflecting a decrease in glucose reabsorption and an increased glycolysis. Such a reversible reprogramming of glucose handling and oxygen dependence of kidney cells by GC7 represents a pharmacological opportunity in ischaemic as well as hyperglycaemia-associated pathologies from renal origin.
  5. Cancer Lett. 2021 Mar 10. pii: S0304-3835(21)00093-8. [Epub ahead of print]507 13-25
      Proteasome inhibitors (PIs), used in the treatment of plasma cell myeloma (PCM), interfere with the degradation of misfolded proteins leading to activation of unfolded protein response (UPR) and cell death. However, despite initial strong antimyeloma effects, PCM cells eventually develop acquired resistance to PIs. The pleiotropic role of ʟ-glutamine (Gln) in cellular functions makes inhibition of Gln metabolism a potentially good candidate for combination therapy. Here, we show that PCM cells, both sensitive and resistant to PIs, express membrane Gln transporter (ASCT2), require extracellular Gln for survival, and are sensitive to ASCT2 inhibitors (ASCT2i). ASCT2i synergistically potentiate the cytotoxic activity of PIs by inducing apoptosis and modulating autophagy. Combination of ASCT2 inhibitor V9302 and proteasome inhibitor carfilzomib upregulates the intracellular levels of ROS and oxidative stress markers and triggers catastrophic UPR as shown by upregulated spliced Xbp1 mRNA, ATF3 and CHOP levels. Moreover, analysis of RNA sequencing revealed that the PI in combination with ASCT2i reduced the levels of Gln metabolism regulators such as MYC and NRAS. Analysis of PCM patients' data revealed that upregulated ASCT2 and other Gln metabolism regulators are associated with advanced disease stage and with PIs resistance. Altogether, we identified a potent therapeutic approach that may prevent acquired resistance to PIs and may contribute to the improvement of treatment of patients suffering from PCM.
    Keywords:  Plasma cell myeloma; Proteasome inhibitors; Unfolded protein response; ʟ-glutamine
  6. Commun Biol. 2021 Mar 19. 4(1): 371
      Metabolic plasticity enables cancer cells to switch between glycolysis and oxidative phosphorylation to adapt to changing conditions during cancer progression, whereas metabolic dependencies limit plasticity. To understand a role for the architectural environment in these processes we examined metabolic dependencies of cancer cells cultured in flat (2D) and organotypic (3D) environments. Here we show that cancer cells in flat cultures exist in a high energy state (oxidative phosphorylation), are glycolytic, and depend on glucose and glutamine for growth. In contrast, cells in organotypic culture exhibit lower energy and glycolysis, with extensive metabolic plasticity to maintain growth during glucose or amino acid deprivation. Expression of KRASG12V in organotypic cells drives glucose dependence, however cells retain metabolic plasticity to glutamine deprivation. Finally, our data reveal that mechanical properties control metabolic plasticity, which correlates with canonical Wnt signaling. In summary, our work highlights that the architectural and mechanical properties influence cells to permit or restrict metabolic plasticity.
  7. Cell Death Dis. 2021 Mar 15. 12(3): 277
      Glioma stem cells (GSCs) contribute to therapy resistance and poor outcomes for glioma patients. A significant feature of GSCs is their ability to grow in an acidic microenvironment. However, the mechanism underlying the rewiring of their metabolism in low pH remains elusive. Here, using metabolomics and metabolic flux approaches, we cultured GSCs at pH 6.8 and pH 7.4 and found that cells cultured in low pH exhibited increased de novo purine nucleotide biosynthesis activity. The overexpression of glucose-6-phosphate dehydrogenase, encoded by G6PD or H6PD, supports the metabolic dependency of GSCs on nucleotides when cultured under acidic conditions, by enhancing the pentose phosphate pathway (PPP). The high level of reduced glutathione (GSH) under acidic conditions also causes demand for the PPP to provide NADPH. Taken together, upregulation of G6PD/H6PD in the PPP plays an important role in acidic-driven purine metabolic reprogramming and confers a predilection toward glioma progression. Our findings indicate that targeting G6PD/H6PD, which are closely related to glioma patient survival, may serve as a promising therapeutic target for improved glioblastoma therapeutics. An integrated metabolomics and metabolic flux analysis, as well as considering microenvironment and cancer stem cells, provide a precise insight into understanding cancer metabolic reprogramming.
    Keywords:  Acidic microenvironment; Glioma stem cells; Glucose-6-phosphate dehydrogenase; Metabolomics; Purine metabolism
  8. Heliyon. 2021 Feb;7(2): e06352
      Glioblastoma is a severe cancer with extremely poor survival. Its treatment typically involves a combination of surgery, chemotherapy, and radiation therapy. However, glioma stem-like cells (GSCs)-a subpopulation of tumor-propagating glioblastoma cells-cause post-treatment recurrence and are a major factor in the poor prognosis of the disease. GSCs have higher proliferation than non-GSCs and are more resistant to invasive chemotherapy and radiotherapy. In this study, we subjected GSCs to nutrient starvation (deprived of glucose, glutamine, and calcium) to determine whether cell death can be triggered as a potential strategy to improve treatment outcomes. Flow cytometry revealed that 35.1%, 96.1%, and 99.9% of starved GSCs underwent apoptosis on days 1, 3, and 5, respectively, along with nearly 100% autophagy on all three days. Western blots detected cleaved caspase-3 (an apoptosis marker) and phospho-beclin 1, LC 3B-I, LC 3B-II (autophagy markers) in C6 GSCs after nutrient starvation for 1, 3, 4, and 5 days. Transmission electron microscopic observation of GSC ultrastructure after starvation treatment revealed that compared with control GSCs, starved cells had more pyknotic nuclei, membrane bleb, swollen endoplasmic reticulum, degenerative mitochondria, lipid droplets, and microvilli loss. Thus, nutrient starvation stresses cells by increasing free radicals. Cell stress opens more channels between mitochondria and endoplasmic reticulum. This study demonstrated that nutrient starvation decreases proliferation by approximately 81%, while increasing apoptosis (99.9%) and autophagy (94.6%) in C6 GSCs by the fifth day. Nutrient starvation of GSCs may, therefore, be an effective therapeutic strategy that can trigger apoptotic and autophagic metabolic reprogramming in cancer cells.
    Keywords:  Apoptosis; Autophagy; C6 glioma stem cells; Nutrient starvation
  9. Front Oncol. 2021 ;11 612778
      Most of the cancer related deaths are caused mainly by metastasis. Therefore, it is highly important to unfold the major mechanisms governing metastasis process in cancer. Throughout the metastatic cascade, cells need the ability to survive without attachment to neighboring cells and the original Extra Cellular Matrix (ECM). Recent reports showed that loss of ECM attachment shifts cancer cell metabolism towards glycolysis mostly through hypoxia. However, AMPK, a master metabolic regulator was also found to be upregulated under ECM detached conditions. Therefore, in this work we aimed to understand the consequences of targeting AMPK and other metabolic kinases by a broad kinase inhibitor namely Compound C in ECM detached cancer cells. Results showed that Compound C impacts glycolysis as evident by increased levels of pyruvate, but reduces its conversion to lactate thereby negatively regulating the Warburg effect. Simultaneously, Compound C induces block at multiple levels in TCA cycle as evident from accumulation of various TCA metabolites. Interestingly Compound C significantly reduces glutamine and reduced glutathione levels, suggesting loss of antioxidant potential of ECM detached cancer cells. Further, we found increased in metabolites associated with nucleotide synthesis, one carbon metabolism and PPP pathway during Compound C treatment of ECM detached cells. Finally, we also found induction in metabolites associated with DNA damage in ECM detached cancer cells during Compound C treatment, suggesting DNA damage regulatory role of metabolic kinases. Overall, our results showed that Compound C represses pyruvate to lactate conversion, reduces antioxidant potential and invokes DNA damage in ECM detached cancer cells. Our data provides a comprehensive metabolic map of ECM detached cancer cells that can be targeted with a broad kinase inhibitor, is Compound C. The data can be used for designing new combinational therapies to eradicate ECM detached cancer cells.
    Keywords:  AMP-activated protein kinase; compound C; extra cellular matrix detachment; metabolomic analysis; oxidative phosphorylation
  10. Sci Adv. 2021 Mar;pii: eabe3588. [Epub ahead of print]7(12):
      Tumor microenvironment-responsive therapy has enormous application potential in the diagnosis and treatment of cancer. The glutathione (GSH) level has been shown to be significantly increased in tumor tissues. Thus, GSH can be used as an effective endogenous molecule for diagnosis and tumor microenvironment-activated therapy. In this study, we prepared a tumor microenvironment-induced, absorption spectrum red-shifted, iron-copper co-doped polyaniline nanoparticle (Fe-Cu@PANI). The Cu(II) in this nanoparticle can undergo a redox reaction with GSH in tumors. The redox reaction induces a red shift in the absorption spectrum of the Fe-Cu@PANI nanoparticles from the visible to the near-infrared region accompanying with the etching of this nanoparticle, which simultaneously activates tumor photoacoustic imaging and photothermal therapy, thereby improving the accuracy of in vivo tumor imaging and the efficiency of photothermal therapy. The nanoparticle prepared in this study has broad application prospects in the diagnosis and treatment of cancer.
  11. Life Sci. 2021 Mar 16. pii: S0024-3205(21)00350-7. [Epub ahead of print] 119365
      AIMS: Vascular smooth muscle cells (VSMCs) are involved in the pathogenesis of many human cardiovascular diseases. They modulate their phenotype from "contractile" to "synthetic" in response to changes in local environmental cues. How glutamine regulates the differentiation of VSMCs and the underlying mechanisms remain largely unknown.MAIN METHODS: Here, we explored the effects of various doses of glutamine (0 mM, 1 mM, 2 mM, and 4 mM) on the proliferation, migration, and phenotypic switch of human VSMCs in vitro. Glutamine dose-dependently enhanced VSMC proliferation, and markedly increased VSMC migration.
    KEY FINDINGS: Notably, glutamine promoted the phenotypic switch of VSMCs towards a synthetic phenotype, as evidenced by significantly decreased expression of contractile markers myosin heavy chain 11 (MYH11) and calponin while increased expression of synthetic markers collagen I and vimentin. Importantly, these changes upon glutamine treatments were attenuated after additional treatments with glutamine metabolism inhibitor BPTES. Additionally, glutamine downregulated miR-143 expression, and miR-143 inactivation alone resulted in enhanced proliferation, migration, and promoted the synthetic phenotype of VSMCs. Moreover, Thy-1 cell surface antigen (THY1) was validated as a downstream target of miR-143, and THY1 expression was upregulated by glutamine in VSMCs. Furthermore, either miR-143 overexpression or THY1 silencing abolished the effect of glutamine on proliferation, migration, and phenotypic switch of VSMCs, supporting a novel glutamine-miR-143-THY1 pathway in modulating VSMC functions.
    SIGNIFICANCE: This study demonstrated a novel mechanism of glutamine in modulation of VSMC phenotypic switch by targeting miR-143 and THY1, and provides significant insight on targeted therapy of patients with cardiovascular diseases.
    Keywords:  Glutamine; Phenotypic switch; Synthetic phenotype; THY1; Vascular smooth muscle cells; miR-143
  12. Nat Rev Gastroenterol Hepatol. 2021 Mar 19.
      Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive disease with a 5-year survival rate of <10%. The tumour microenvironment (TME) of PDAC is characterized by excessive fibrosis and deposition of extracellular matrix, termed desmoplasia. This unique TME leads to high interstitial pressure, vascular collapse and low nutrient and oxygen diffusion. Together, these factors contribute to the unique biology and therapeutic resistance of this deadly tumour. To thrive in this hostile environment, PDAC cells adapt by using non-canonical metabolic pathways and rely on metabolic scavenging pathways such as autophagy and macropinocytosis. Here, we review the metabolic pathways that PDAC use to support their growth in the setting of an austere TME. Understanding how PDAC tumours rewire their metabolism and use scavenging pathways under environmental stressors might enable the identification of novel therapeutic approaches.
  13. Adv Exp Med Biol. 2021 ;1286 15-48
      Several studies have exploited the metabolic hallmarks that distinguish between normal and cancer cells, aiming at identifying specific targets of anti-cancer drugs. It has become apparent that metabolic flexibility allows cancer cells to survive during high anabolic demand or the depletion of nutrients and oxygen. Cancers can reprogram their metabolism to the microenvironments by increasing aerobic glycolysis to maximize ATP production, increasing glutaminolysis and anabolic pathways to support bioenergetic and biosynthetic demand during rapid proliferation. The increased key regulatory enzymes that support the relevant pathways allow us to design small molecules which can specifically block activities of these enzymes, preventing growth and metastasis of tumors. In this review, we discuss metabolic adaptation in cancers and highlight the crucial metabolic enzymes involved, specifically those involved in aerobic glycolysis, glutaminolysis, de novo fatty acid synthesis, and bioenergetic pathways. Furthermore, we also review the success and the pitfalls of the current anti-cancer drugs which have been applied in pre-clinical and clinical studies.
    Keywords:  Bioenergetic; Cancer; Drug target; Enzymes; Metabolism
  14. Front Chem. 2021 ;9 640994
      Glutamine 5'-phosphoribosylpyrophosphate amidotransferase (GPATase) catalyzes the synthesis of phosphoribosylamine, pyrophosphate, and glutamate from phosphoribosylpyrophosphate, as well as glutamine at two sites (i.e., glutaminase and phosphoribosylpyrophosphate sites), through a 20 Å NH3 channel. In this study, conventional molecular dynamics (cMD) simulations and enhanced sampling accelerated molecular dynamics (aMD) simulations were integrated to characterize the mechanism for coordination catalysis at two separate active sites in the enzyme. Results of cMD simulations illustrated the mechanism by which two substrate analogues, namely, DON and cPRPP, affect the structural stability of GPATase from the perspective of dynamic behavior. aMD simulations obtained several key findings. First, a comparison of protein conformational changes in the complexes of GPATase-DON and GPATase-DON-cPRPP showed that binding cPRPP to the PRTase flexible loop (K326 to L350) substantially effected the formation of the R73-DON salt bridge. Moreover, only the PRTase flexible loop in the GPATase-DON-cPRPP complex could remain closed and had sufficient space for cPRPP binding, indicating that binding of DON to the glutamine loop had an impact on the PRTase flexible loop. Finally, both DON and cPRPP tightly bonded to the two domains, thereby inducing the glutamine loop and the PRTase flexible loop to move close to each other. This movement facilitated the transfer of NH3 via the NH3 channel. These theoretical results are useful to the ongoing research on efficient inhibitors related to GPATase.
    Keywords:  5′-phosphoribosylpyrophosphate amidotransferase; accelerated molecular dynamics simulations; conformational changes; molecular dynamics simulations; substrates analogue
  15. Medicine (Baltimore). 2021 Mar 12. 100(10): e25098
      BACKGROUND: Irritable bowel syndrome (IBS) is one the common medical condition of functional GI disorder (FGD) characterized by bowel-related symptoms without other organic gastrointestinal (GI) disease. Compound Glutamine Entersoluble Capsules(CGEC),a compound preparation in which each capsule contains 120 mg L-glutamine, 50 mg ginseng, 50 mg licorice, 50 mg Atractylodes macrocephala and 50 mg Poria cocos, have been reported the efficacy of CGEC for patients with IBS in improving the clinical symptoms and quality of patients' life. However, there is no a systematic review related to CGEC for IBS to this day. In this study, we will systematically evaluate the effectiveness and safety of CGEC in the treatment of IBS-D with a meta-analysis method, so as to provide a solid evidence for clinical practice.METHODS: In this study, a literature search was performed by using the Chinese and English databases, which include PubMed, Embase, MEDLINE, Cochrane Library Central Register of Controlled Trials, China National Knowledge Infrastructure (CNKI) database, Wanfang Data Knowledge Service Platform, the VIP information resource integration service platform (cqvip), China Biology Medicine Disc (Sino Med),and the Chinese Clinical Trial Registry (ChiCTR), to find the related literature of CGEC in the treatment of IBS published from the inception date of each predefined database upto January 2021. The evaluation of the risk of bias for eligible studies will be performed by two investigators. Data synthesis will be performed by RevMan 5.4 software. Heterogeneity between studies can be assessed by a heterogeneity X2 test. The degree of heterogeneity among multiple included studies can be measured by I2. The stability of systematic review or meta-analysis outcomes will be evaluated by Sensitivity analysis. Reporting bias will be evaluated by funnel plot. Finally, The Grading of Recommendations Assessment, Development and Evaluation (GRADE) will be used to assess the quality of evidence obtained.
    RESULTS: The results of this study will be published in a peer-reviewed journal.
    CONCLUSION: Whether it is the effectiveness and safety of CGEC in the treatment of IBS will be judged in the result of this systematic review.