Glutaminase 1 inhibition reduces thymidine synthesis in NSCLC

The Glutaminase-1 Inhibitor [11C-carbony]BPTES: Synthesis and Positron Emission Tomography Study in Mice

Bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide (BPTES) is a selective inhibitor of glutaminase-1 (GLS1), consequently inhibiting glutaminolysis. BPTES is known for its potent antitumor activity and plays a significant role in senescent cell removal. In this study, we synthesized [¹¹C-carbonyl]BPTES ([¹¹C]BPTES) as a positron emission tomography (PET) probe for the first time and assessed its biodistribution in mice using PET. [¹¹C]BPTES was synthesized by the reaction of an amine precursor () with [¹¹C-carbonyl]phenylacetyl acid anhydride ([¹¹C]2), which was prepared from [¹¹C]CO₂ and benzyl magnesium chloride, followed by in situ treatment with isobutyl chloroformate. The decay-corrected isolated radiochemical yield of [¹¹C]BPTES was 9.5% (based on [¹¹C]CO₂) during a synthesis time of 40 min. A PET study with [¹¹C]BPTES showed high uptake levels of radioactivity in the liver, kidney, and small intestine of mice.

Glutamine metabolism in breast cancer and possible therapeutic targets

Cancer is characterized by metabolic reprogramming, which is a hot topic in tumor treatment research. Cancer cells alter metabolic pathways to promote their growth, and the common purpose of these altered metabolic pathways is to adapt the metabolic state to the uncontrolled proliferation of cancer cells. Most cancer cells in a state of nonhypoxia will increase the uptake of glucose and produce lactate, called the Warburg effect. Increased glucose consumption is used as a carbon source to support cell proliferation, including nucleotide, lipid and protein synthesis. In the Warburg effect, pyruvate dehydrogenase activity decreases, thereby disrupting the TCA cycle. In addition to glucose, glutamine is also an important nutrient for the growth and proliferation of cancer cells, an important carbon bank and nitrogen bank for the growth and proliferation of cancer cells, providing ribose, nonessential amino acids, citrate, and glycerin necessary for cancer cell growth and proliferation and compensating for the reduction in oxidative phosphorylation pathways in cancer cells caused by the Warburg effect. In human plasma, glutamine is the most abundant amino acid. Normal cells produce glutamine via glutamine synthase (GLS), but the glutamine synthesized by tumor cells is insufficient to meet their high growth needs, resulting in a "glutamine-dependent phenomenon." Most cancers have an increased glutamine demand, including breast cancer. Metabolic reprogramming not only enables tumor cells to maintain the reduction-oxidation (redox) balance and commit resources to biosynthesis but also establishes heterogeneous metabolic phenotypes of tumor cells that are distinct from those of nontumor cells. Thus, targeting the metabolic differences between tumor and nontumor cells may be a promising and novel anticancer strategy. Glutamine metabolic compartments have emerged as promising candidates, especially in TNBC and drug-resistant breast cancer. In this review, the latest discoveries of breast cancer and glutamine metabolism are discussed, novel treatment methods based on amino acid transporters and glutaminase are discussed, and the relationship between glutamine metabolism and breast cancer metastasis, drug resistance, tumor immunity and ferroptosis are explained, which provides new ideas for the clinical treatment of breast cancer.

circ_0000376 knockdown suppresses non-small cell lung cancer cell tumor properties by the miR-545-3p/PDPK1 pathway

Non-small cell lung cancer (NSCLC) accounts for 80% of total lung cancers, which are the main killer of cancer-related death worldwide. Circular RNA (circRNA) has been found to modulate NSCLC development. However, the role of circ_0000376 in NSCLC development has been underreported. The present work showed that circ_0000376 and 3-phos-phoinositide-dependent protein kinase-1 (PDPK1) expression were dramatically increased, but miR-545-3p was decreased in NSCLC tissues and cells. circ_0000376 expression was closely associated with lymph node metastasis, tumor-node-metastasis stage, and tumor size of NSCLC patients. circ_0000376 knockdown repressed NSCLC cell proliferation, migration, invasion, and glutaminolysis but induced cell apoptosis. Additionally, miR-545-3p bound to circ_0000376, and circ_0000376 regulated cell phenotypes by associating with miR-545-3p. MiR-545-3p also participated in NSCLC cell proliferation, migration, invasion, apoptosis, and glutaminolysis by targeting PDPK1. Further, circ_0000376 absence repressed tumor formation in vivo. Collectively, circ_0000376 regulated NSCLC cell tumor properties by the miR-545-3p/PDPK1 axis, suggesting that circ_0000376 could be employed as a therapeutic target for NSCLC.

The strategic roles of four enzymes in the interconnection between metabolism and oncogene activation in non-small cell lung cancer: Therapeutic implications

NSCLC is the leading cause of cancer mortality and represents a major challenge in cancer therapy. Intrinsic and acquired anticancer drug resistance are promoted by hypoxia and HIF-1α. Moreover, chemoresistance is sustained by the activation of key signaling pathways (such as RAS and its well-known downstream targets PI3K/AKT and MAPK) and several mutated oncogenes (including KRAS and EGFR among others). In this review, we highlight how these oncogenic factors are interconnected with cell metabolism (aerobic glycolysis, glutaminolysis and lipid synthesis). Also, we stress the key role of four metabolic enzymes (PFK1, dimeric-PKM2, GLS1 and ACLY), which promote the activation of these oncogenic pathways in a positive feedback loop. These four tenors orchestrating the coordination of metabolism and oncogenic pathways could be key druggable targets for specific inhibition. Since PFK1 appears as the first tenor of this orchestra, its inhibition (and/or that of its main activator PFK2/PFKFB3) could be an efficacious strategy against NSCLC. Citrate is a potent physiologic inhibitor of both PFK1 and PFKFB3, and NSCLC cells seem to maintain a low citrate level to sustain aerobic glycolysis and the PFK1/PI3K/EGFR axis. Awaiting the development of specific non-toxic inhibitors of PFK1 and PFK2/PFKFB3, we propose to test strategies increasing citrate levels in NSCLC tumors to disrupt this interconnection. This could be attempted by evaluating inhibitors of the citrate-consuming enzyme ACLY and/or by direct administration of citrate at high doses. In preclinical models, this "citrate strategy" efficiently inhibits PFK1/PFK2, HIF-1α, and IGFR/PI3K/AKT axes. It also blocks tumor growth in RAS-driven lung cancer models, reversing dedifferentiation, promoting T lymphocytes tumor infiltration, and increasing sensitivity to cytotoxic drugs.

Therapeutic Potential of Glutamine Pathway in Lung Cancer

Cancer cells tend to obtain the substances needed for their development depending on altering metabolic characteristics. Among the reorganized metabolic pathways, Glutamine pathway, reprogrammed to be involved in the physiological process including energy supply, biosynthesis and redox homeostasis, occupies an irreplaceable role in tumor cells and has become a hot topic in recent years. Lung cancer currently maintains a high morbidity and mortality rate among all types of tumors and has been a health challenge that researchers have longed to overcome. Therefore, this study aimed to clarify the essential role of glutamine pathway played in the metabolism of lung cancer and its potential therapeutic value in the interventions of lung cancer.

Establishment of live-cell-based coupled assay system for identification of compounds to modulate metabolic activities of cells

In this study, we present a live-cell-based fluorometric coupled assay system to identify the compounds that can regulate the targeted metabolic pathways in live cells. The assay is established through targeting specific metabolic pathways and using "input" and "output" metabolite pairs. The changes in the extracellular output that are generated and released into the extracellular media from the input are assessed as the activity of the pathway. The screening for the glycolytic pathway and amino acid metabolism reveals the activities of the present drugs, 6-BIO and regorafenib, that regulate the metabolic fate of tumor cells.

Mechanism of miR-455-3 in suppressing epithelial-mesenchymal transition and angiogenesis of non-small cell lung cancer cells

The tumor-suppressing role of miR-455-3p has been reported in lung cancer, but the working mechanism remains to be fully elucidated. This study aims to explore the possible mechanism of miR-455-3p in regulating epithelial-mesenchymal transition (EMT) progression and angiogenesis in non-small cell lung cancer (NSCLC) cells.The expressions of miR-455-3p, HSF1, GLS1, and EMT-related proteins (E-cadherin, N-cadherin, vimentin, and Snail-1) in both NSCLC tissues and cell lines were determined by RT-qPCR and western blot. After cell transfection, cell proliferation and angiogenesis ability on NSCLC cells were assessed by MTT and tube formation assay. The binding of miR-455-3p with HSF1 was measured by luciferase reporter gene assay, while the interaction between HSF1 and GLS1 was determined by co-immunoprecipitation assay (Co-IP).HSF1 was highly expressed in NSCLC tissues and cells. Inhibition of HSF1 expression or overexpression of miR-455-3p in NSCLC cells can suppress cell proliferation, angiogenesis ability, and EMT progression. miR-455-3p was found to negatively regulate HSF1 expression. Co-transfection of miR-455-3p overexpression and HSF1 inhibition in NSCLC cells showed that miR-455-3p can partially counteract the effect of HSF1 in NSCLC cells. HSF1 can interact with GLS1 and elevate the expression of GLS1. GLS1 can partially abolish the suppressive effect of miR-455-3p in NSCLC cells.miR-455-3p can bind HSF1 to suppress the GLS1 in NSCLC cells, therefore suppressing EMT progression and angiogenesis of NSCLC cells.

The glutaminase (CgGLS-1) mediates anti-bacterial immunity by prompting cytokine synthesis and hemocyte apoptosis in Pacific oyster Crassostrea gigas

Glutaminase, an amidohydrolase enzyme that hydrolyzes glutamine to glutamate, plays crucial roles in various immunomodulatory processes such as cell apoptosis, proliferation, migration, and secretion of cytokines. In the present study, a glutaminase homologue (designated as CgGLS-1) was identified from Pacific oyster Crassostrea gigas, whose open reading frame was of 1836 bp. CgGLS-1 exhibited high sequence identity with vertebrate kidney-type GLS, and closely clustered with their homologues from mollusc C. virginica. The enzyme activity of recombinant CgGLS-1 protein (rCgGLS-1) was estimated to be 1.705 U/mg. CgGLS-1 mRNA was constitutively expressed in all the tested tissues of oysters, with the highest expression level in hemocytes. CgGLS-1 mRNA expression in hemocytes was significantly up-regulated and peaked at 6 h (2.07-fold, p < 0.01) after lipopolysaccharide (LPS) stimulation. The CgGLS-1 protein was mainly distributed in the cytoplasm with a significant co-location with mitochondria in oyster hemocytes. The content of Glu in the oyster serum was significantly decreased after the inhibition of CgGLS-1 using specific inhibitor Bis-2- [5-(phenyl acetamido)-1,3,4-thiadiazol-2-yl] ethyl sulfide (BPTES), and the expression levels of CgmGluR6, CgAP-1, cytokines CgIL17-5 and CgTNF-1 were significantly decreased after BPTES and LPS stimulation. The transcripts of CgCaspase3 as well as the apoptosis index of hemocytes were also decreased. These results collectively suggest that CgGLS-1 is the enzyme to synthesize Glu in oyster, which can modulate anti-bacterial immunity by regulating the secretion of pro-inflammatory cytokines CgIL17-5 and CgTNF-1, as well as hemocyte apoptosis.

Glutamine Inhibition Reduces Iatrogenic Laryngotracheal Stenosis

OBJECTIVE/HYPOTHESIS

Glutamine inhibition has been demonstrated an antifibrotic effect in iatrogenic laryngotracheal stenosis (iLTS) scar fibroblasts in vitro. We hypothesize that broadly active glutamine antagonist, DON will reduce collagen formation and fibrosis-associated gene expression in iLTS mice.

STUDY DESIGN

Prospective controlled animal study.

METHODS

iLTS in mice were induced by chemomechanical injury of the trachea using a bleomycin-coated wire brush. PBS or DON (1.3 mg/kg) were administered by intraperitoneal injection (i.p.) every other day. Laryngotracheal complexes were harvested at days 7 and 14 after the initiation of DON treatment for the measurement of lamina propria thickness, trichrome stain, immunofluorescence staining of collagen 1, and fibrosis-associated gene expression.

RESULTS

The study demonstrated that DON treatment reduced lamina propria thickness (P = .025) and collagen formation in trichrome stain and immunofluorescence staining of collagen 1. In addition, DON decreased fibrosis-associated gene expression in iLTS mice. At day 7, DON inhibited Col1a1 (P < .0001), Col3a1 (P = .0046), Col5a1 (P < .0001), and Tgfβ (P = .023) expression. At day 14, DON reduced Co1a1 (P = .0076) and Tgfβ (P = .023) expression.

CONCLUSIONS

Broadly active glutamine antagonist, DON, significantly reduces fibrosis in iLTS mice. These results suggest that the concept of glutamine inhibition may be a therapeutic option to reduce fibrosis in the laryngotracheal stenosis.

LEVEL OF EVIDENCE

N/A Laryngoscope, 131:E2125-E2130, 2021.

Thiadiazole derivatives as anticancer agents

In spite of substantial progress made toward understanding cancer pathogenesis, this disease remains one of the leading causes of mortality. Thus, there is an urgent need to develop novel, more effective anticancer therapeutics. Thiadiazole ring is a versatile scaffold widely studied in medicinal chemistry. Mesoionic character of this ring allows thiadiazole-containing compounds to cross cellular membrane and interact strongly with biological targets. Consequently, these compounds exert a broad spectrum of biological activities. This review presents the current state of knowledge on thiadiazole derivatives that demonstrate in vitro and/or in vivo efficacy across the cancer models with an emphasis on targets of action. The influence of the substituent on the compounds' activity is depicted. Furthermore, the results from clinical trials assessing thiadiazole-containing drugs in cancer patients are summarized.

ATP Production Relies on Fatty Acid Oxidation Rather than Glycolysis in Pancreatic Ductal Adenocarcinoma

Glycolysis is known as the main pathway for ATP production in cancer cells. However, in cancer cells, glucose deprivation for 24 h does not reduce ATP levels, whereas it does suppress lactate production. In this study, metabolic pathways were blocked to identify the main pathway of ATP production in pancreatic ductal adenocarcinoma (PDAC). Blocking fatty acid oxidation (FAO) decreased ATP production by 40% in cancer cells with no effect on normal cells. The effects of calorie balanced high- or low-fat diets were tested to determine whether cancer growth is modulated by fatty acids instead of calories. A low-fat diet caused a 70% decrease in pancreatic preneoplastic lesions compared with the control, whereas a high-fat diet caused a two-fold increase in preneoplastic lesions accompanied with increase of ATP production in the Kras (G12D)/Pdx1-cre PDAC model. The present results suggest that ATP production in cancer cells is dependent on FAO rather than on glycolysis, which can be a therapeutic approach by targeting cancer energy metabolism.

Loss of SLC25A11 causes suppression of NSCLC and melanoma tumor formation

Background

Fast growing cancer cells require greater amounts of ATP than normal cells. Although glycolysis was suggested as a source of anabolic metabolism based on lactate production, the main source of ATP to support cancer cell metabolism remains unidentified.

Methods

We have proposed that the oxoglutarate carrier SLC25A11 is important for ATP production in cancer by NADH transportation from the cytosol to mitochondria as a malate. We have examined not only changes of ATP and NADH but also changes of metabolites after SLC25A11 knock down in cancer cells.

Findings

The mitochondrial electron transport chain was functionally active in cancer cells. The cytosolic to mitochondrial NADH ratio was higher in non-small cell lung cancer (NSCLC) and melanoma cells than in normal cells. This was consistent with higher levels of the oxoglutarate carrier SLC25A11. Blocking malate transport by knockdown of SLC25A11 significantly impaired ATP production and inhibited the growth of cancer cells, which was not observed in normal cells. In in vivo experiments, heterozygote of SLC25A11 knock out mice suppressed KRAS^LA2 lung tumor formation by cross breeding.

Interpretation

Cancer cells critically depended on the oxoglutarate carrier SLC25A11 for transporting NADH from cytosol to mitochondria as a malate form for the purpose of ATP production. Therefore blocking SLC25A11 may have an advantage in stopping cancer growth by reducing ATP production.

Fund

The Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Science and ICT to SYK (NRF-2017R1A2B2003428).

Cancer Energy Metabolism: Shutting Power off Cancer Factory

In 1923, Dr. Warburg had observed that tumors acidified the Ringer solution when 13 mM glucose was added, which was identified as being due to lactate. When glucose is the only source of nutrient, it can serve for both biosynthesis and energy production. However, a series of studies revealed that the cancer cell consumes glucose for biosynthesis through fermentation, not for energy supply, under physiological conditions. Recently, a new observation was made that there is a metabolic symbiosis in which glycolytic and oxidative tumor cells mutually regulate their energy metabolism. Hypoxic cancer cells use glucose for glycolytic metabolism and release lactate which is used by oxygenated cancer cells. This study challenged the Warburg effect, because Warburg claimed that fermentation by irreversible damaging of mitochondria is a fundamental cause of cancer. However, recent studies revealed that mitochondria in cancer cell show active function of oxidative phosphorylation although TCA cycle is stalled. It was also shown that blocking cytosolic NADH production by aldehyde dehydrogenase inhibition, combined with oxidative phosphorylation inhibition, resulted in up to 80% decrease of ATP production, which resulted in a significant regression of tumor growth in the NSCLC model. This suggests a new theory that NADH production in the cytosol plays a key role of ATP production through the mitochondrial electron transport chain in cancer cells, while NADH production is mostly occupied inside mitochondria in normal cells.

Environmental cystine drives glutamine anaplerosis and sensitizes cancer cells to glutaminase inhibition

Many mammalian cancer cell lines depend on glutamine as a major tri-carboxylic acid (TCA) cycle anaplerotic substrate to support proliferation. However, some cell lines that depend on glutamine anaplerosis in culture rely less on glutamine catabolism to proliferate in vivo. We sought to understand the environmental differences that cause differential dependence on glutamine for anaplerosis. We find that cells cultured in adult bovine serum, which better reflects nutrients available to cells in vivo, exhibit decreased glutamine catabolism and reduced reliance on glutamine anaplerosis compared to cells cultured in standard tissue culture conditions. We find that levels of a single nutrient, cystine, accounts for the differential dependence on glutamine in these different environmental contexts. Further, we show that cystine levels dictate glutamine dependence via the cystine/glutamate antiporter xCT/SLC7A11. Thus, xCT/SLC7A11 expression, in conjunction with environmental cystine, is necessary and sufficient to increase glutamine catabolism, defining important determinants of glutamine anaplerosis and glutaminase dependence in cancer.

Cancer cells need to consume certain nutrients in order to grow, and some cancer drugs work by affecting the ability of the cells to use these nutrients. For decades researchers have grown cancer cells in petri dishes with standard nutrient formulations (also known as tissue culture), but the nutrients available to cancer cells in tissue culture are not the same as those found in the body.

Cancer cells growing in tissue culture consume large amounts of a nutrient called glutamine. These cells die when exposed to a class of drugs called glutaminase inhibitors that prevent them from processing glutamine. However, when these same cancer cells grow as tumors in animals, they process less glutamine and are not affected by glutaminase inhibitors. So what differences are there between growing cancer cells in tumors and tissue culture that explain this different reliance on glutamine?

Muir et al. reasoned that changing the levels of nutrients available to cancer cells might change what these cells consume, and so grew human cancer cells in cow serum (which has a similar nutrient content to blood in humans and other mammals). Indeed, these cells consumed less glutamine and responded to glutaminase inhibitors in a way that is similar to how tumors in the body respond to these drugs. Comparing the nutrient content of cow serum and typical tissue culture formulations revealed that high levels of the nutrient cystine cause the cells to rely more on glutamine.

The results presented by Muir et al. suggest that cancer cells in tumors could be made to consume more glutamine and that this would make them sensitive to glutaminase inhibitors – a possibility that will be studied in future work. Exposing cultured cancer cells to nutrient levels closer to those found in the body may also better predict how tumor cells use nutrients and respond to some treatments.

Dual targeting of glutaminase 1 and thymidylate synthase elicits death synergistically in NSCLC

Glutaminase 1 (GLS1) expression is increased in non-small cell lung cancer (NSCLC). GLS1 knockdown using siRNA or inhibition using bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide (BPTES) induced cell cycle arrest with significant reduction of ATP level while levels of reactive oxygen species or glutathione were not affected in NSCLC cell lines. Recently we found that NSCLC significantly depends on cytosol NADH for ATP production. GLS1 remarkably contributes to ATP production through transferring cytosolic NADH into mitochondria via malate-aspartate shuttle by supply of glutamate in NSCLC. Regulation of malate-aspartate shuttle by knockdown or inhibition of glutamic-oxaloacetic transaminase 2 or malate dehydrogenase 2 mimicked GLS1 knockdown, which induced cell death with ATP reduction in NSCLC. Therefore, GLS1 inhibition induced cell cycle arrest with ATP depletion by glutamate reduction. Dual inhibition with BPTES and thymidylate synthase inhibitor, 5-fluorouracil (5-FU), elicits cell death synergistically through cell cycle arrest in NSCLC. A preclinical xenograft model of NSCLC showed remarkable anti-tumour effect synergistically in the BPTES and 5-FU dual therapy group.