Augmented drug resistance of osteosarcoma cells within decalcified bone matrix scaffold: The role of glutamine metabolism.

Due to the lack of a precise in vitro model that can mimic the nature microenvironment in osteosarcoma, the understanding of its resistance to chemical drugs remains limited. Here, we report a novel three-dimensional model of osteosarcoma constructed by seeding tumor cells (MG-63 and MNNG/HOS Cl no. 5) within demineralized bone matrix scaffolds. Demineralized bone matrix scaffolds retain the original components of the natural bone matrix (hydroxyapatite and collagen type I), and possess good biocompatibility allowing osteosarcoma cells to proliferate and aggregate into clusters within the pores. Growing within the scaffold conferred elevated resistance to doxorubicin on MG-63 and MNNG/HOS Cl no. 5 cell lines as compared to two-dimensional cultures. Transcriptomic analysis showed an increased enrichment for drug resistance genes along with enhanced glutamine metabolism in osteosarcoma cells in demineralized bone matrix scaffolds. Inhibition of glutamine metabolism resulted in a decrease in drug resistance of osteosarcoma, which could be restored by α-ketoglutarate supplementation. Overall, our study suggests that microenvironmental cues in demineralized bone matrix scaffolds can enhance osteosarcoma drug responses and that targeting glutamine metabolism may be a strategy for treating osteosarcoma drug resistance.

TIM-3/Galectin-9 interaction and glutamine metabolism in AML cell lines, HL-60 and THP-1.

BACKGROUND: T cell immunoglobulin and mucin-domain containing-3 (TIM-3) is a cell surface molecule that was first discovered on T cells. However, recent studies revealed that it is also highly expressed in acute myeloid leukemia (AML) cells and it is related to AML progression. As, Glutamine appears to play a prominent role in malignant tumor progression, especially in their myeloid group, therefore, in this study we aimed to evaluate the relation between TIM-3/Galectin-9 axis and glutamine metabolism in two types of AML cell lines, HL-60 and THP-1. METHODS: Cell lines were cultured in RPMI 1640 which supplemented with 10% FBS and 1% antibiotics. 24, 48, and 72 h after addition of recombinant Galectin-9 (Gal-9), RT-qPCR analysis, RP-HPLC and gas chromatography techniques were performed to evaluate the expression of glutaminase (GLS), glutamate dehydrogenase (GDH) enzymes, concentration of metabolites; Glutamate (Glu) and alpha-ketoglutarate (α-KG) in glutaminolysis pathway, respectively. Western blotting and MTT assay were used to detect expression of mammalian target of rapamycin complex (mTORC) as signaling factor, GLS protein and cell proliferation rate, respectively. RESULTS: The most mRNA expression of GLS and GDH in HL-60 cells was seen at 72 h after Gal-9 treatment (p = 0.001, p = 0.0001) and in THP-1 cell line was observed at 24 h after Gal-9 addition (p = 0.001, p = 0.0001). The most mTORC and GLS protein expression in HL-60 and THP-1 cells was observed at 72 and 24 h after Gal-9 treatment (p = 0.0001), respectively. MTT assay revealed that Gal-9 could promote cell proliferation rate in both cell lines (p = 0.001). Glu concentration in HL-60 and α-KG concentration in both HL-60 (p = 0.03) and THP-1 (p = 0.0001) cell lines had a decreasing trend. But, Glu concentration had an increasing trend in THP-1 cell line (p = 0.0001). CONCLUSION: Taken together, this study suggests TIM-3/Gal-9 interaction could promote glutamine metabolism in HL-60 and THP-1 cells and resulting in AML development.

Biomimetic Nanomedicine Targeting Orchestrated Metabolism Coupled with Regulatory Factors to Disrupt the Metabolic Plasticity of Breast Cancer.

Targeting nutrient metabolism has been proposed as an effective therapeutic strategy to combat breast cancer because of its high nutrient requirements. However, metabolic plasticity enables breast cancer cells to survive under unfavorable starvation conditions. The key mammalian target regulators rapamycin (mTOR) and hypoxia-inducible-factor-1 (HIF-1) tightly link the dynamic metabolism of glutamine and glucose to maintain nutrient flux. Blocking nutrient flow also induces autophagy to recycle nutrients in the autophagosome, which exacerbates metastasis and tumor progression. Compared to other common cancers, breast cancer is even more dependent on mTOR and HIF-1 to orchestrate the metabolic network. Therefore, we develop a cascade-boosting integrated nanomedicine to reprogram complementary metabolism coupled with regulators in breast cancer. Glucose oxidase efficiently consumes glucose, while the delivery of rapamycin inside limits the metabolic flux of glutamine and uncouples the feedback regulation of mTOR and HIF-1. The hydroxyl radical generated in a cascade blocks the later phase of autophagy without nutrient recycling. This nanomedicine targeting orchestrated metabolism can disrupt the coordination of glucose, amino acids, nucleotides, lipids, and other metabolic pathways in breast cancer tissues, effectively improving the durable antitumor effect and prognosis of breast cancer. Overall, the cascade-boosting integrated system provides a viable strategy to address cellular plasticity and efficient enzyme delivery.

Sijunzi Tang improves gefitinib resistance by regulating glutamine metabolism.

Lung cancer is a major health concern and significant barrier to human well-being and social development. Although targeted therapy has shown remarkable progress in the treatment of lung cancer, the emergence of drug resistance has limited its clinical efficacy. Sijunzi Tang (SJZ) is a classical Chinese herbal formula known for tonifying qi and nourishing the lungs, has been recognized for its potential in lung cancer management. However, the underlying mechanism of its combined use with anti-cancer drugs remains unclear. Here, we investigated the anti-lung cancer efficacy and underlying mechanisms of the combination of gefitinib and SJZ in gefitinib-resistant human lung adenocarcinoma cells (PC-9/GR). We conducted in vitro and in vivo experiments using histopathology and targeted metabolomics approaches. Our results demonstrated that the combination of SJZ and gefitinib exhibited synergistic effects on tumor growth inhibition in PC-9/GR-bearing nude mice. Notably, the co-administration of SJZ and gefitinib synergistically promoted tumor cell apoptosis, potentially through the regulation of BAX and BCL-2 expression. Immunohistochemistry and western blot analysis found down-regulation of GLS, GS, and SLC1A5 expression in the co-administration group compared to the control and the individual treatment groups. Targeted metabolomics revealed significant alterations in the plasma glutamine metabolic markers glutamine, alanine, succinate, glutamate, and pyruvate. Of the glutamine metabolism markers measured in tumor tissues, glutamine and pyruvate demonstrated significant differences across the treatment groups. These findings suggest that administration of SJZ improves gefitinib resistance in the treatment of lung cancer without toxic effects. Moreover, SJZ may affect glutamine metabolism by regulating key targets involved in glutamine metabolism (SLC1A5, GLS, and GS) and modulating the levels of related metabolic markers, ultimately reducing gefitinib resistance.

Targeting CXCR1 alleviates hyperoxia-induced lung injury through promoting glutamine metabolism.

Although increasing evidence suggests potential iatrogenic injury from supplemental oxygen therapy, significant exposure to hyperoxia in critically ill patients is inevitable. This study shows that hyperoxia causes lung injury in a time- and dose-dependent manner. In addition, prolonged inspiration of oxygen at concentrations higher than 80% is found to cause redox imbalance and impair alveolar microvascular structure. Knockout of C-X-C motif chemokine receptor 1 (Cxcr1) inhibits the release of reactive oxygen species (ROS) from neutrophils and synergistically enhances the ability of endothelial cells to eliminate ROS. We also combine transcriptome, proteome, and metabolome analysis and find that CXCR1 knockdown promotes glutamine metabolism and leads to reduced glutathione by upregulating the expression of malic enzyme 1. This preclinical evidence suggests that a conservative oxygen strategy should be recommended and indicates that targeting CXCR1 has the potential to restore redox homeostasis by reducing oxygen toxicity when inspiratory hyperoxia treatment is necessary.

Mitochondria-anchoring self-assembled nanoparticles for multi-path energy depletion: A "nano bomb" in chemo-co-starvation therapy.

As the main systemic treatment for triple-negative breast cancer (TNBC), the bleak medical prognosis of chemotherapy resulted in impaired life quality by tumor recurrence and metastasis. The feasible cancer starvation therapy could inhibit tumor progression by blocking energy supplements, however, the mono-therapeutic modality showed limited curing efficacy due to heterogeneity and abnormal energy metabolism of TNBC. Thus, the development of a synergistic nano-therapeutic modality involving different anti-tumor mechanisms to simultaneously transport medicines to the organelle where metabolism took place, might remarkably improve curing efficacy, targeting ability, and bio-safety. Herein, the hybrid BLG@TPGS NPs were prepared by doping multi-path energy inhibitors Berberine (BBR) and Lonidamine (LND) as well as the chemotherapeutic agent Gambogic acid (GA). Our research indicated that Nanobomb-BLG@TPGS NPs inherited the mitochondria targeting ability from BBR to accumulate precisely at the "energy factory" mitochondria, and then induce starvation therapy to efficiently eradicated cancer cells by coordinately powered off tumor cells via a "three-prone strategy" to cut off mitochondrial respiration, glycolysis, and glutamine metabolism. The inhibition of tumor proliferation and migration was enlarged by the synergistic combination with chemotherapy. Besides, apoptosis via mitochondria pathway and mitochondria fragmentation supported the hypothesis that NPs eliminated MDA-MB-231 cells by violently attacking MDA-MB-231 cells and especially the mitochondria. In summary, this synergistic chemo-co-starvation nanomedicine proposed an innovative site-specific targeting strategy for improved tumor treatment and decreased toxicity to normal tissues, which provided an option for clinical TNBC-sensitive treatment.

An active glutamine/α-ketoglutarate/HIF-1α axis prevents pregnancy loss by triggering decidual IGF1+GDF15+NK cell differentiation.

Deficiency of decidual NK (dNK) cell number and function has been widely regarded as an important cause of spontaneous abortion. However, the metabolic mechanism underlying the crosstalk between dNK cells and embryonic trophoblasts during early pregnancy remains largely unknown. Here, we observed that enriched glutamine and activated glutaminolysis in dNK cells contribute to trophoblast invasion and embryo growth by insulin-like growth factor-1 (IGF-1) and growth differentiation factor-15 (GDF-15) secretion. Mechanistically, these processes are dependent on the downregulation of EGLN1-HIF-1α mediated by α-ketoglutarate (α-KG). Blocking glutaminolysis with the GLS inhibitor BPTES or the glutamate dehydrogenase inhibitor EGCG leads to early embryo implantation failure, spontaneous abortion and/or fetal growth restriction in pregnant mice with impaired trophoblast invasion. Additionally, α-KG supplementation significantly alleviated pregnancy loss mediated by defective glutaminolysis in vivo, suggesting that inactivated glutamine/α-ketoglutarate metabolism in dNK cells impaired trophoblast invasion and induced pregnancy loss.

Combined exploration of the mechanism of Sang Xing Decoction in the treatment of smoke-induced acute bronchitis from protein and metabolic levels.

Sang Xing decoction (SXD) is a typical prescription for treating "warm dryness" in traditional Chinese medicine (TCM), which is equivalent to respiratory diseases such as acute bronchitis in modern medicine. However, its mechanism of action remains unclear. In this study, the representative components of SXD were characterized using liquid chromatography-tandem mass spectrometry (LC-MS). The key targets, signaling pathways, and metabolic pathways associated with SXD in the treatment of acute bronchitis were identified via network prediction and metabolomics. A rat model of acute bronchitis was also established using mixed smoke, systematic in vivo experiments such as histopathological analyses, enzyme-linked immunosorbent assay (ELISA), immunofluorescence, immunohistochemistry and western blotting were conducted to evaluate the network prediction results. An in-depth analysis of the targeted quantitative results was performed using the SIMCA software and MetaboAnalyst website. The results revealed that 50 active compounds and 45 key targets were screened and clustered with 20 approved drugs. The NF-κB signaling pathway, oxidative stress, and glutamine metabolism were associated with the therapeutic mechanism of SXD in acute bronchitis. In vivo experiments showed that SXD may maintain the production of inflammatory factors by regulating the PI3K/Akt/NF-κB signaling pathway, improving the metabolism of glutamine and glutamate to reduce oxidative stress, and inhibiting apoptosis. Simultaneously, the possibility of using SXD as an adjuvant drug for COVID-19 treatment was also revealed. This research will lay the foundation for the modern clinical application of SXD and promote the promotion and innovation of TCM.

Osmundacetone modulates mitochondrial metabolism in non-small cell lung cancer cells by hijacking the glutamine/glutamate/α-KG metabolic axis.

BACKGROUND: Osmundacetone (OSC) is a bioactive phenolic compound isolated from Phellinus igniarius and that was shown to exert cytotoxic effects on cancer cells in our previous work. The antiproliferative impact of OSC on non-small cell lung cancer (NSCLC) and the underlying mechanisms, however, have not been studied. PURPOSE: This study aimed to explore the antiproliferative effect of OSC on NSCLC cells and the mechanisms involved. METHODS: Cell viability, colony formation and cell cycle distribution were measured following exposure to OSC in vitro. The anticancer activity of OSC was also examined using a xenograft growth assay in vivo. Furthermore, serum metabolomics analysis by GC-MS was done to detect alterations in the metabolic profile. Next, expression of GLS1 and GLUD1, the key enzymes in glutamine metabolism, was evaluated using RT-PCR and western blot. α-KG and NADH metabolites were assessed by ELISA. Mitochondrial functions and morphology were evaluated using the JC-1 probe and transmission electron microscopy, respectively. The ATP production rate in mitochondria of cells with OSC treatment was determined using a Seahorse XFe24 Analyzer. RESULTS: OSC selectively reduced the proliferation of A549 and H460 cells. OSC triggered G2/M cell cycle arrest and decreased the cell clone formation. A mouse xenograft model revealed that OSC inhibited tumor growth in vivo. Findings of serum metabolomics analyses indicated that the anticancer function of OSC was related to disorders of glutamine metabolism. Such a speculation was further verified by the expression level of GLUD1, which was downregulated by OSC treatment. Concentrations of the related metabolites α-KG and NADH were reduced in response to OSC treatment. Moreover, OSC led to disorganization of the mitochondrial ultrastructure and a decrease in mitochondrial membrane potential. OSC also decreased ATP production via oxidative phosphorylation (OXPHOS) but did not affect glycolysis in NSCLC cells. CONCLUSION: The key role of OSC in mitochondrial energy metabolism in NSCLC cells is to suppress tumor development and cell proliferation downregulating GLUD1 to inhibit the glutamine/glutamate/α-KG metabolic axis and OXPHOS. It indicats that OSC might be a potential natural agent for personalized medicine and an anticancer metabolic modulator in NSCLC chemotherapy.

Filamentous GLS1 promotes ROS-induced apoptosis upon glutamine deprivation via insufficient asparagine synthesis.

GLS1 orchestrates glutaminolysis and promotes cell proliferation when glutamine is abundant by regenerating TCA cycle intermediates and supporting redox homeostasis. CB-839, an inhibitor of GLS1, is currently under clinical investigation for a variety of cancer types. Here, we show that GLS1 facilitates apoptosis when glutamine is deprived. Mechanistically, the absence of exogenous glutamine sufficiently reduces glutamate levels to convert dimeric GLS1 to a self-assembled, extremely low-Km filamentous polymer. GLS1 filaments possess an enhanced catalytic activity, which further depletes intracellular glutamine. Functionally, filamentous GLS1-dependent glutamine scarcity leads to inadequate synthesis of asparagine and mitogenome-encoded proteins, resulting in ROS-induced apoptosis that can be rescued by asparagine supplementation. Physiologically, we observed GLS1 filaments in solid tumors and validated the tumor-suppressive role of constitutively active, filamentous GLS1 mutants K320A and S482C in xenograft models. Our results change our understanding of GLS1 in cancer metabolism and suggest the therapeutic potential of promoting GLS1 filament formation.

Inhibition of lncRNA NEAT1 sensitizes medulloblastoma cells to cisplatin through modulating the miR-23a-3p-glutaminase (GLS) axis.

Medulloblastoma (MB) is a commonly occurring brain malignancy in adolescence. Currently, the combination of chemotherapy with subsequent irradiation is a regular therapeutic strategy. However, high dosage of chemotherapy is associated with drug resistance and side effects. The long non-coding RNA nuclear paraspeckle assembly transcript 1 (NEAT1), which is frequently overexpressed in diverse human tumors, is correlated with worse survival rate in cancer patients. Currently, the precise roles of NEAT1 in MB and chemoresistance remain unclear. Our study aimed to investigate the biological functions of NEAT1 in cisplatin-resistant medulloblastoma. We report that NEAT1 was significantly upregulated in medulloblastoma patient specimens. Silencing NEAT1 significantly suppressed MB cell proliferation and sensitized MB cells to cisplatin. In cisplatin-resistant MB cell line, DAOY Cis R, NEAT1 expression, and glutamine metabolism were remarkably upregulated in cisplatin-resistant cells. Under low glutamine supply, cisplatin-resistant cells displayed increased cisplatin sensitivity. Bioinformatical analysis and luciferase assay uncovered that NEAT1 functions as a ceRNA of miR-23a-3p to downregulate its expressions in MB cells. Moreover, miR-23a-3p was apparently downregulated in MB patient tissues and cisplatin resistant MB cells. We identified GLS (glutaminase), a glutamine metabolism enzyme, was directly targeted by miR-23a-3p in MB cells. Rescue experiments demonstrated restoration of miR-23a-3p in NEAT1-overexpressing DAOY cisplatin resistant cells successfully overcame the NEAT1-promoted cisplatin resistance by targeting GLS. In general, our results revealed new molecular mechanisms for the lncRNA-NEAT1-mediated cisplatin sensitivity of MB.

Distinct Roles of Glutamine Metabolism in Benign and Malignant Cartilage Tumors With IDH Mutations.

Enchondromas and chondrosarcomas are common cartilage neoplasms that are either benign or malignant, respectively. The majority of these tumors harbor mutations in either IDH1 or IDH2. Glutamine metabolism has been implicated as a critical regulator of tumors with IDH mutations. Using genetic and pharmacological approaches, we demonstrated that glutaminase-mediated glutamine metabolism played distinct roles in enchondromas and chondrosarcomas with IDH1 or IDH2 mutations. Glutamine affected cell differentiation and viability in these tumors differently through different downstream metabolites. During murine enchondroma-like lesion development, glutamine-derived α-ketoglutarate promoted hypertrophic chondrocyte differentiation and regulated chondrocyte proliferation. Deletion of glutaminase in chondrocytes with Idh1 mutation increased the number and size of enchondroma-like lesions. In contrast, pharmacological inhibition of glutaminase in chondrosarcoma xenografts reduced overall tumor burden partially because glutamine-derived non-essential amino acids played an important role in preventing cell apoptosis. This study demonstrates that glutamine metabolism plays different roles in tumor initiation and cancer maintenance. Supplementation of α-ketoglutarate and inhibiting GLS may provide a therapeutic approach to suppress enchondroma and chondrosarcoma tumor growth, respectively. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Rapid metabolic and bioenergetic adaptations of astrocytes under hyperammonemia - a novel perspective on hepatic encephalopathy.

Hepatic encephalopathy (HE) is a well-studied, neurological syndrome caused by liver dysfunctions. Ammonia, the major toxin during HE pathogenesis, impairs many cellular processes within astrocytes. Yet, the molecular mechanisms causing HE are not fully understood. Here we will recapitulate possible underlying mechanisms with a clear focus on studies revealing a link between altered energy metabolism and HE in cellular models and in vivo. The role of the mitochondrial glutamate dehydrogenase and its role in metabolic rewiring of the TCA cycle will be discussed. We propose an updated model of ammonia-induced toxicity that may also be exploited for therapeutic strategies in the future.

The pathways related to glutamine metabolism, glutamine inhibitors and their implication for improving the efficiency of chemotherapy in triple-negative breast cancer.

Breast cancer (BC) is a heterogeneous cancer with multiple subtypes affecting women worldwide. Triple-negative breast cancer (TNBC) is a prominent subtype of BC with poor prognosis and an aggressive phenotype. Recent understanding of metabolic reprogramming supports its role in the growth of cancer cells and their adaptation to their microenvironment. The Warburg effect is characterized by the shift from oxidative to reductive metabolism and external secretion of lactate. The Warburg effect prevents the use of the required pyruvate in the tricarboxylic acid (TCA) cycle progressing through pyruvate dehydrogenase inactivation. Therefore, it is a major regulatory mechanism to promote glycolysis and disrupt the TCA cycle. Glutamine (Gln) can supply the complementary energy for cancer cells. Additionally, it is the main substrate to support bioenergetics and biosynthetic activities in cancer cells and plays a vital role in a wide array of other processes such as ferroptosis. Thus, the switching of glucose to Gln in the TCA cycle toward reductive Gln metabolism is carried out by hypoxia-inducible factors (HIFs) conducted through the Warburg effect. The literature suggests that the addiction of TNBC to Gln could facilitate the proliferation and invasiveness of these cancers. Thus, Gln metabolism inhibitors, such as CB-839, could be applied to manage the carcinogenic properties of TNBC. Such inhibitors, along with conventional chemotherapy agents, can potentially improve the efficiency and efficacy of TNBC treatment. In this review, we discuss the associations between glucose and Gln metabolism and control of cancer cell growth from the perspective that Gln metabolism inhibitors could improve the current chemotherapy drug effects.

Metabolic Intersection of Cancer and Cardiovascular Diseases: Opportunities for Cancer Therapy.

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.

A novel tumor suppressor CECR2 down regulation links glutamine metabolism contributes tumor growth in laryngeal squamous cell carcinoma.

PURPOSE: Glutamine plays an important role in tumor metabolism and progression. This research aimed to find out how Gln exert their effects on laryngeal squamous cell carcinoma (LSCC). METHODS: Cell proliferation was measured by CCK8 and EdU assay, mitochondrial bioenergetic activity was measured by mitochondrial stress tests. Gene expression profiling was revealed by RNA sequencing and validated by RT-qPCR. In LSCC patients, protein expression in tumor and adjacent tissues was examined and scored by IHC staining. RNAi was performed by stably expressed shRNA in TU177 cells. In vivo tumor growth analysis was performed using a nude mouse tumorigenicity model. RESULTS: Gln deprivation suppressed TU177 cell proliferation, which was restored by αKG supplementation. By transcriptomic analysis, we identified CECR2, which encodes a histone acetyl-lysine reader, as the downstream target gene for Gln and αKG. In LSCC patients, the expression of CECR2 in tumors was lower than adjacent tissues. Furthermore, deficiency of CECR2 promoted tumor cell growth both in vitro and in vivo, suggesting it has tumor suppressor effects. Besides, cell proliferation inhibited by Gln withdrawal could be restored by CECR2 depletion, and the proliferation boosted by αKG supplementation could be magnified either, suggested that CECR2 feedback suppressed Gln and αKG's effect on tumor growth. Transcriptomic profiling revealed CECR2 regulated the expression of a series of genes involved in tumor progression. CONCLUSION: We confirmed the Gln-αKG-CECR2 axis contributes to tumor growth in LSCC. This finding provided a potential therapeutic opportunity for the use of associated metabolites as a potential treatment for LSCC.

The glutamine antagonist prodrug JHU-083 slows malignant glioma growth and disrupts mTOR signaling.

BACKGROUND: Metabolic reprogramming is a common feature in cancer, and it is critical to facilitate cancer cell growth. Isocitrate Dehydrogenase 1/2 (IDH1 and IDH2) mutations (IDHmut) are the most common genetic alteration in glioma grade II and III and secondary glioblastoma and these mutations increase reliance on glutamine metabolism, suggesting a potential vulnerability. In this study, we tested the hypothesis that the brain penetrant glutamine antagonist prodrug JHU-083 reduces glioma cell growth. MATERIAL AND METHODS: We performed cell growth, cell cycle, and protein expression in glutamine deprived or Glutaminase (GLS) gene silenced glioma cells. We tested the effect of JHU-083 on cell proliferation, metabolism, and mTOR signaling in cancer cell lines. An orthotopic IDH1R132H glioma model was used to test the efficacy of JHU-083 in vivo. RESULTS: Glutamine deprivation and GLS gene silencing reduced glioma cell proliferation in vitro in glioma cells. JHU-083 reduced glioma cell growth in vitro, modulated cell metabolism, and disrupted mTOR signaling and downregulated Cyclin D1 protein expression, through a mechanism independent of TSC2 modulation and glutaminolysis. IDH1R132H isogenic cells preferentially reduced cell growth and mTOR signaling downregulation. In addition, guanine supplementation partially rescued IDHmut glioma cell growth, mTOR signaling, and Cyclin D1 protein expression in vitro. Finally, JHU-083 extended survival in an intracranial IDH1 mut glioma model and reduced intracranial pS6 protein expression. CONCLUSION: Targeting glutamine metabolism with JHU-083 showed efficacy in preclinical models of IDHmut glioma and measurably decreased mTOR signaling.

Anticancer Properties of Lobetyolin, an Essential Component of Radix Codonopsis (Dangshen).

Lobetyolin (LBT) is a polyacetylene glycoside found in diverse medicinal plants but mainly isolated from the roots of Codonopsis pilosula, known as Radix Codonopsis or Dangshen. Twelve traditional Chinese medicinal preparations containing Radix Codonopsis were identified; they are generally used to tonify spleen and lung Qi and occasionally to treat cancer. Here we have reviewed the anticancer properties of Codonopsis extracts, LBT and structural analogs. Lobetyolin and lobetyolinin are the mono- and bis-glucosylated forms of the polyacetylenic compound lobetyol. Lobetyol and LBT have shown activities against several types of cancer (notably gastric cancer) and we examined the molecular basis of their activity. A down-regulation of glutamine metabolism by LBT has been evidenced, contributing to drug-induced apoptosis and tumor growth inhibition. LBT markedly reduces both mRNA and protein expression of the amino acid transporter Alanine-Serine-Cysteine Transporter 2 (ASCT2). Other potential targets are proposed here, based on the structural analogy with other anticancer compounds. LBT and related polyacetylene glycosides should be further considered as potential anticancer agents, but more work is needed to evaluate their efficacy, toxicity, and risk-benefit ratio.

Endogenous production of glutamine and plasma glutamine concentration in critically ill patients.

BACKGROUND: Glutamine plasma concentrations outside the normal range at intensive care unit (ICU) admission are associated with unfavorable outcomes. Based on the hypothesis that hypoglutaminemia in the ICU is the result of an increased utilization of glutamine which cannot be fully met by endogenous production, extra glutamine supplementation has been advocated to ICU patients with hypoglutaminemia. However, it is still unclear whether there is a causal relation between hypo- and hyperglutaminemia and outcomes. Present guidelines advise against supplementation, although there is no evidence available for patients with hypoglutaminemia. The pathophysiology of abnormal glutamine levels and whether glutamine production or glutamine utilization is compromised is largely unknown. Therefore, the aim of this study was to elucidate the relationship between plasma glutamine levels and the endogenous glutamine production in ICU patients. METHOD: In this observational study, a technique using a small bolus of intravenous glutamine with an isotopic label was used to measure glutamine production. RESULTS: There was a statistically significant correlation between de novo endogenous production of glutamine (not emanating directly from protein breakdown) and plasma glutamine concentrations in the low and normal range in circulatory stabilized ICU patients (n = 19), R2 = 0.35 (P ≤ 0.01). CONCLUSION: The predictive value of a low plasma glutamine concentration at ICU admission on outcomes may thus be related to a low endogenous production, which may need to be supplemented in the best interest of this cohort of patients.

Aspulvinone O, a natural inhibitor of GOT1 suppresses pancreatic ductal adenocarcinoma cells growth by interfering glutamine metabolism.

BACKGROUND: Distinctive from their normal counterparts, cancer cells exhibit unique metabolic dependencies on glutamine to fuel anabolic processes. Specifically, pancreatic ductal adenocarcinoma (PDAC) cells rely on an unconventional metabolic pathway catalyzed by aspartate transaminase 1 (GOT1) to rewire glutamine metabolism and support nicotinamide adenine dinucleotide phosphate (NADPH) production. Thus, the important role of GOT1 in energy metabolism and Reactive Oxygen Species (ROS) balance demonstrates that targeting GOT1 may serve as an important therapeutic target in PDAC. METHODS: To assay the binding affinity between Aspulvinone O (AO) and GOT1 proteins, the virtual docking, microscale thermophoresis (MST), cellular thermal shift assay (CETSA) and drug affinity responsive target stability (DARTS) methods were employed. GOT1 was silenced in several PDAC cell lines. The level of OCR and ECR were assayed by seahorse. To evaluate the in vivo anti-tumor efficacy of AO, the xenograft model was built in CB17/scid mouse. RESULTS: Screening of an in-house natural compound library identified the AO as a novel inhibitor of GOT1 and repressed glutamine metabolism, which sensitizes PDAC cells to oxidative stress and suppresses cell proliferation. Virtual docking analysis suggested that AO could bind to the active site of GOT1 and form obvious hydrophobic interaction with Trp141 together with hydrogen bonds with Thr110 and Ser256. Further in vitro validation, including MST, CETSA and DARTS, further demonstrated the specific combining capacity of AO. We also show that the selective inhibition of GOT1 by AO significantly reduces proliferation of PDAC in vitro and in vivo. CONCLUSIONS: Taken together, our findings identify AO as a potent bioactive inhibitor of GOT1 and a novel anti-tumour agent for PDAC therapy.