The Combined Metabolically Oriented Effect of Fucoidan from the Brown Alga Saccharina cichorioides and Its Carboxymethylated Derivative with 2-Deoxy-D-Glucose on Human Melanoma Cells

Melanoma is the most aggressive and treatment-resistant form of skin cancer. It is phenotypically characterized by aerobic glycolysis that provides higher proliferative rates and resistance to cell death. The glycolysis regulation in melanoma cells by means of effective metabolic modifiers represents a promising therapeutic opportunity. This work aimed to assess the metabolically oriented effect and mechanism of action of fucoidan from the brown alga Saccharina cichorioides (ScF) and its carboxymethylated derivative (ScFCM) in combination with 2-deoxy-D-glucose (2-DG) on the proliferation and colony formation of human melanoma cell lines SK-MEL-28, SK-MEL-5, and RPMI-7951. The metabolic profile of melanoma cells was determined by the glucose uptake and Lactate-GloTM assays. The effect of 2-DG, ScF, ScFCM, and their combination on the proliferation, colony formation, and activity of glycolytic enzymes was assessed by the MTS, soft agar, and Western blot methods, respectively. When applied separately, 2-DG (IC50 at 72 h = 8.7 mM), ScF (IC50 at 72 h > 800 µg/mL), and ScFCM (IC50 at 72 h = 573.9 μg/mL) inhibited the proliferation and colony formation of SK-MEL-28 cells to varying degrees. ScF or ScFCM enhanced the inhibiting effect of 2-DG at low, non-toxic concentrations via the downregulation of Glut 1, Hexokinase II, PKM2, LDHA, and pyruvate dehydrogenase activities. The obtained results emphasize the potential of the use of 2-DG in combination with algal fucoidan or its derivative as metabolic modifiers for inhibition of melanoma SK-MEL-28 cell proliferation.

2DG and glycolysis as therapeutic targets for status epilepticus

2-deoxy-D-glucose (2DG) is a glucose analog differing from glucose only by removal of an oxygen atom at the 2 position, which prevents the isomerization of glucose-6-phosphate to fructose-6-phosphate, and thereby reversibly inhibits glycolysis. PET studies of regional brain glucose utilization positron-emitting 18F-2DG demonstrate that brain regions generating seizures have diminished glucose utilization during interictal conditions, but rapidly transition to markedly increased glucose delivery and utilization during seizures, particularly in status epilepticus (SE). 2-deoxy-D-glucose has acute antiseizure actions in multiple in vivo and in vitro seizure models, including models of SE induced by the chemo convulsants pilocarpine and kainic acid, suggesting that focal enhanced delivery of 2DG to ictal brain circuits is a potential novel anticonvulsant intervention for the treatment of SE.

The Glycolysis Inhibitor 2-Deoxy-D-Glucose Exerts Different Neuronal Effects at Circuit and Cellular Levels, Partially Reverses Behavioral Alterations and does not Prevent NADPH Diaphorase Activity Reduction in the Intrahippocampal Kainic Acid Model of Temporal Lobe Epilepsy

Temporal lobe epilepsy is the most drug-resistant type with the highest incidence among the other focal epilepsies. Metabolic manipulations are of great interest among others, glycolysis inhibitors like 2-deoxy D-glucose (2-DG) being the most promising intervention. Here, we sought to investigate the effects of 2-DG treatment on cellular and circuit level electrophysiological properties using patch-clamp and local field potentials recordings and behavioral alterations such as depression and anxiety behaviors, and changes in nitric oxide signaling in the intrahippocampal kainic acid model. We found that epileptic animals were less anxious, more depressed, with more locomotion activity. Interestingly, by masking the effect of increased locomotor activity on the parameters of the zero-maze test, no altered anxiety behavior was noted in epileptic animals. However, 2-DG could partially reverse the behavioral changes induced by kainic acid. The findings also showed that 2-DG treatment partially suppresses cellular level alterations while failing to reverse circuit-level changes resulting from kainic acid injection. Analysis of NADPH-diaphorase positive neurons in the CA1 area of the hippocampus revealed that the number of positive neurons was significantly reduced in dorsal CA1 of the epileptic animals and 2-DG treatment did not affect the diminishing effect of kainic acid on NADPH-d+ neurons in the CA1 area. In the control group receiving 2-DG, however, an augmented NADPH-d+ cell number was noted. These data suggest that 2-DG cannot suppress epileptiform activity at the circuit-level in this model of epilepsy and therefore, may fail to control the seizures in temporal lobe epilepsy cases.

2-Deoxy-D-glucose and combined 2-Deoxy-D-glucose/albendazole exhibit therapeutic efficacy against Echinococcus granulosus protoscoleces and experimental alveolar echinococcosis

2-Deoxy-D-glucose (2-DG) is a glucose analog used as a promising anticancer agent. It exerts its effects by inhibiting the glycolytic energy metabolism to deplete cells of energy. The larval stage of Echinococcus relies on glycolysis for energy production. Therefore, in this study, we investigated the in vitro and in vivo efficacy of 2-DG against the larval stage of Echinococcus granulosus and E. multilocularis. 2-DG exhibited significant time- and dose-dependent effects against in vitro cultured E. granulosus protoscoleces and E. multilocularis metacestodes. A daily oral administration of 500 mg/kg 2-DG in E. multilocularis-infected mice effectively reduced the weight of metacestodes. Notably, the combination treatment, either 2-DG (500 mg/kg/day) + albendazole (ABZ) (200 mg/kg/day) or 2-DG (500 mg/kg/day) + half-dose of ABZ (100 mg/kg/day), exhibited a potent therapeutic effect against E. multilocularis, significantly promoting the reduction of metacestodes weight compared with the administration of 2-DG or ABZ alone. Furthermore, the combination significantly promoted apoptosis of the cells of metacestodes and inhibited glycolysis in metacestodes, compared with the administration of 2-DG or ABZ alone. In conclusion, 2-DG exerts an effective activity against the larval stage of Echinococcus. Thus, it may be a promising anti-Echinococcus drug, and its combination with ABZ may provide a new strategy for the treatment of echinococcosis in humans.

Echinococcosis is a serious but neglected helminthic zoonosis caused by the larval stage of Echinococcus granulosus and E. multilocularis. At present, clinical pharmacotherapy of echinococcosis, such as albendazole (ABZ) and mebendazole, has limited effectiveness. Thus, the development of novel therapeutic drugs for human echinococcosis is urgently needed. 2-Deoxy-D-glucose (2-DG) is a glucose analog used as a promising anticancer agent, and it exerts its effects by inhibiting the glycolytic energy metabolism to deplete cells of energy. Echinococcus in the host depends on glycolysis for energy production and glycolysis intermediates for other metabolic processes. Therefore, in this study, we investigated the efficacy of 2-DG against Echinococcus. 2-DG exerted an effective in vitro and in vivo activity against E. granulosus protoscoleces and E. multilocularis metacestodes, and the combination of this drug with ABZ further improved the therapeutic effect. Therefore, 2-DG can be developed as a promising anti-Echinococcus drug, and its combination with ABZ may provide a new strategy for the treatment of human echinococcosis in the future.

Blood-based untargeted metabolomics in relapsing-remitting multiple sclerosis revealed the testable therapeutic target

Metabolic aberrations impact the pathogenesis of multiple sclerosis (MS) and possibly can provide clues for new treatment strategies. Using untargeted metabolomics, we measured serum metabolites from 35 patients with relapsing-remitting multiple sclerosis (RRMS) and 14 healthy age-matched controls. Of 632 known metabolites detected, 60 were significantly altered in RRMS. Bioinformatics analysis identified an altered metabotype in patients with RRMS, represented by four changed metabolic pathways of glycerophospholipid, citrate cycle, sphingolipid, and pyruvate metabolism. Interestingly, the common upstream metabolic pathway feeding these four pathways is the glycolysis pathway. Real-time bioenergetic analysis of the patient-derived peripheral blood mononuclear cells showed enhanced glycolysis, supporting the altered metabolic state of immune cells. Experimental autoimmune encephalomyelitis mice treated with the glycolytic inhibitor 2-deoxy-D-glucose ameliorated the disease progression and inhibited the disease pathology significantly by promoting the antiinflammatory phenotype of monocytes/macrophage in the central nervous system. Our study provided a proof of principle for how a blood-based metabolomic approach using patient samples could lead to the identification of a therapeutic target for developing potential therapy.

Cholinergic anti-inflammatory pathway ameliorates murine experimental Th2-type colitis by suppressing the migration of plasmacytoid dendritic cells

Ulcerative colitis (UC) is a chronic inflammatory bowel disease. Several studies have demonstrated that α7 nicotinic acetylcholine receptors (α7nAChRs) exert anti-inflammatory effects on immune cells and nicotine suppress UC onset and relapse. Plasmacytoid dendritic cells (pDCs) reportedly accumulate in the colon of UC patients. Therefore, we investigated the pathophysiological roles of α7nAChRs on pDCs in the pathology of UC using oxazolone (OXZ)-induced Th2-type colitis with BALB/c mice. 2-deoxy-D-glucose, a central vagal stimulant suppressed OXZ colitis, and nicotine also ameliorated OXZ colitis with suppressing Th2 cytokines, which was reversed by α7nAChR antagonist methyllycaconitine. Additionally, α7nAChRs were expressed on pDCs, which were located very close to cholinergic nerve fibers in the colon of OXZ mice. Furthermore, nicotine suppressed CCL21-induced bone marrow-derived pDC migration due to Rac 1 inactivation, which was reversed by methyllycaconitine, a JAK2 inhibitor AG490 or caspase-3 inhibitor AZ-10417808. CCL21 was mainly expressed in the isolated lymphoid follicles (ILFs) of the colon during OXZ colitis. The therapeutic effect of cholinergic pathway on OXZ colitis probably through α7nAChRs on pDCs were attributed to the suppression of pDC migration toward the ILFs. Therefore, the activation of α7nAChRs has innovative therapeutic potential for the treatment of UC.

Inhibition of AXL enhances chemosensitivity of human ovarian cancer cells to cisplatin via decreasing glycolysis

Anexelekto (AXL), a member of the TYRO3-AXL-MER (TAM) family of receptor tyrosine kinases (RTK), is overexpressed in varieties of tumor tissues and promotes tumor development by regulating cell proliferation, migration and invasion. In this study, we investigated the role of AXL in regulating glycolysis in human ovarian cancer (OvCa) cells. We showed that the expression of AXL mRNA and protein was significantly higher in OvCa tissue than that in normal ovarian epithelial tissue. In human OvCa cell lines suppression of AXL significantly inhibited cell proliferation, and increased the sensitivity of OvCa cells to cisplatin, which also proved by nude mice tumor formation experiment. KEGG analysis showed that AXL was significantly enriched in the glycolysis pathways of cancer. Changes in AXL expression in OvCa cells affect tumor glycolysis. We demonstrated that the promotion effect of AXL on glycolysis was mediated by phosphorylating the M2 isoform of pyruvate kinase (PKM2) at Y105. AXL expression was significantly higher in cisplatin-resistant OvCa cells A2780/DDP compared with the parental A2780 cells. Inhibition of AXL decreased the level of glycolysis in A2780/DDP cells, and increased the cytotoxicity of cisplatin against A2780/DDP cells, suggesting that AXL-mediated glycolysis was associated with cisplatin resistance in OvCa. In conclusion, this study demonstrates for the first time that AXL is involved in the regulation of the Warburg effect. Our results not only highlight the clinical value of targeting AXL, but also provide theoretical basis for the combination of AXL inhibitor and cisplatin in the treatment of OvCa.

Activation of unfolded protein response overcomes Ibrutinib resistance in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most widespread type of non-Hodgkin lymphoma (NHL). As the most aggressive form of the DLBCL, the activated B-cell-like (ABC) subtype is often resistant to standard chemotherapies. Bruton's tyrosine kinase (BTK) inhibitor ibrutinib provides a potential therapeutic approach for the DLBCL but fails to improve the outcome in the phase III trial. In the current study, we investigated the molecular mechanisms underlying ibrutinib resistance and explored new combination therapy with ibrutinib. We generated an ibrutinib-resistant ABC-DLBCL cell line (OCI-ly10-IR) through continuous exposure to ibrutinib. Transcriptome analysis of the parental and ibrutinib-resistant cell lines revealed that the ibrutinib-resistant cells had significantly lower expression of the unfolded protein response (UPR) marker genes. Overexpression of one UPR branch-XBP1s greatly potentiated ibrutinib-induced apoptosis in both sensitive and resistant cells. The UPR inhibitor tauroursodeoxycholic acid (TUDCA) partially reduced the apoptotic rate induced by the ibrutinib in sensitive cells. The UPR activator 2-deoxy-D-glucose (2-DG) in combination with the ibrutinib triggered even greater cell growth inhibition, apoptosis, and stronger calcium (Ca2+) flux inhibition than either of the agents alone. A combination treatment of ibrutinib (15 mg·kg-1·d-1, po.) and 2-DG (500 mg/kg, po, b.i.d.) synergistically retarded tumor growth in NOD/SCID mice bearing OCI-ly10-IR xenograft. In addition, ibrutinib induced the UPR in the sensitive cell lines but not in the resistant cell lines of the DLBCL. There was also a combined synergistic effect in the primary resistant DLBCL cell lines. Overall, our results suggest that targeting the UPR could be a potential combination strategy to overcome ibrutinib resistance in the DLBCL.

Inhibiting glycolysis rescues memory impairment in an intellectual disability Gdi1-null mouse

OBJECTIVES

GDI1 gene encodes for αGDI, a protein controlling the cycling of small GTPases, reputed to orchestrate vesicle trafficking. Mutations in human GDI1 are responsible for intellectual disability (ID). In mice with ablated Gdi1, a model of ID, impaired working and associative short-term memory was recorded. This cognitive phenotype worsens if the deletion of αGDI expression is restricted to neurons. However, whether astrocytes, key homeostasis providing neuroglial cells, supporting neurons via aerobic glycolysis, contribute to this cognitive impairment is unclear.

METHODS

We carried out proteomic analysis and monitored [¹⁸F]-fluoro-2-deoxy-d-glucose uptake into brain slices of Gdi1 knockout and wild type control mice. d-Glucose utilization at single astrocyte level was measured by the Förster Resonance Energy Transfer (FRET)-based measurements of cytosolic cyclic AMP, d-glucose and L-lactate, evoked by agonists selective for noradrenaline and L-lactate receptors. To test the role of astrocyte-resident processes in disease phenotype, we generated an inducible Gdi1 knockout mouse carrying the Gdi1 deletion only in adult astrocytes and conducted behavioural tests.

RESULTS

Proteomic analysis revealed significant changes in astrocyte-resident glycolytic enzymes. Imaging [¹⁸F]-fluoro-2-deoxy-d-glucose revealed an increased d-glucose uptake in Gdi1 knockout tissue versus wild type control mice, consistent with the facilitated d-glucose uptake determined by FRET measurements. In mice with Gdi1 deletion restricted to astrocytes, a selective and significant impairment in working memory was recorded, which was rescued by inhibiting glycolysis by 2-deoxy-d-glucose injection.

CONCLUSIONS

These results reveal a new astrocyte-based mechanism in neurodevelopmental disorders and open a novel therapeutic opportunity of targeting aerobic glycolysis, advocating a change in clinical practice.

One-stop radiotherapeutic targeting of primary and distant osteosarcoma to inhibit cancer progression and metastasis using 2DG-grafted graphene quantum dots

The application of radiotherapy (RT) to treat osteosarcoma (OS) has been limited, but this is starting to change as the ability to target radiation energy to niches improves. Furthermore, lung cancer from highly metastatic OS is a major cause of death, so it is critical to explore new strategies to tackle metastasis. In this study, we designed a nanoscale radiosensitizer by grafting 2-deoxy-d-glucose (2DG) onto graphene quantum dots (GQD) to achieve OS targeting and boost RT efficacy. Combining the use of 2DG-grafted GQDs (2DG-g-GQD) with RT produced a significant increase in oxidative stress response and DNA damage in the 143B OS cell line compared with RT alone. Moreover, 2DG-g-GQDs selectively associated with 143B cells, and demonstrated the inhibition of migration in a scratch assay. We also demonstrated remarkable improvement in their ability to inhibit tumour progression and lung metastasis in an OS xenograft mouse model. Our results show that the use of 2DG-g-GQDs as OS-targeting radiosensitizers improves their therapeutic outcome and exhibits potential for use in low-dose precision RT for OS.

The Combination of Glycolytic Inhibitor 2-Deoxyglucose and Microbubbles Increases the Effect of 5-Aminolevulinic Acid-Sonodynamic Therapy in Liver Cancer Cells

Sonodynamic therapy (SDT) overcomes the shortcoming of photodynamic therapy in the treatment of cancer. Previous studies indicated that the glycolysis inhibitor 2-deoxyglucose (2-DG) potentiated photodynamic therapy induced tumor cell death and microbubbles (MBs) improved the SDT performance. We hypothesized that the combination of 2-DG and MBs will increase the effect of 5-aminolevulinic acid (ALA)-SDT in HepG2 liver cancer cells. When cells were treated with 5-min ALA-SDT and 2-mmol/L 2-DG, the cell survival rate decreased to 73.0 ± 7.1% and 75.2 ± 7.9%, respectively. Furthermore, 2 mmol/L 2-DG increased 5-min ALA-SDT induced growth inhibition and augmented ALA-SDT induced cell apoptotic rate from 9.8 ± 0.7% to 17.4 ± 2.2%. In the combination group (2-DG and ALA-SDT group), HepG2 cells possessed typical apoptotic characters. 2-DG also increased ALA-SDT associated intracellular reactive oxygen species generation and loss of mitochondrial membrane potential. Moreover, SonoVue MBs had stimulatory function on cell viability inhibition, apoptosis, reactive oxygen species production and mitochondrial membrane potential loss for combination treatment. This study suggests a promising therapeutic strategy using a combination of 2-DG, MBs and ALA-SDT for treating liver cancer.

Manipulating Glucose Metabolism during Different Stages of Viral Pathogenesis Can Have either Detrimental or Beneficial Effects

This report deals with physiological changes and their implication following ocular infection with HSV. This infection usually results in a blinding inflammatory reaction in the cornea, orchestrated mainly by proinflammatory CD4 T cells and constrained in severity by regulatory T cells. In the present report, we make the unexpected finding that blood glucose levels change significantly during the course of infection. Whereas levels remained normal during the early phase of infection when the virus was actively replicating in the cornea, they increased around 2-fold during the time when inflammatory responses to the virus was occurring. We could show that glucose levels influenced the extent of induction of the inflammatory T cell subset in vitro that mainly drives lesions, but not regulatory T cells. Additionally, if glucose utilization was limited in vivo as a consequence of therapy in the inflammatory phase with the drug 2-deoxy-glucose (2DG), lesions were diminished compared with untreated infected controls. In addition, lesions in 2DG-treated animals contained less proinflammatory effectors. Glucose metabolism also influenced the acute phase of infection when the replicating virus was present in the eye. Thus, therapy with 2DG to limit glucose utilization caused mice to become susceptible to the lethal effects of HSV infection, with the virus spreading to the brain causing encephalitis. Taken together, our results indicate that glucose metabolism changed during the course of HSV infection and that modulating glucose levels can influence the outcome of infection, being detrimental or beneficial according to the stage of viral pathogenesis.

Defective glycolysis and the use of 2-deoxy-D-glucose in polycystic kidney disease: from animal models to humans

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited renal disease characterized by bilateral renal cyst formation. ADPKD is one of the most common rare disorders, accounting for ~10% of all patients with end-stage renal disease (ESRD). ADPKD is a chronic disorder in which the gradual expansion of cysts that form in a minority of nephrons eventually causes loss of renal function due to the compression and degeneration of the surrounding normal parenchyma. Numerous deranged pathways have been identified in the cyst-lining epithelia, prompting the design of potential therapies. Several of these potential treatments have proved effective in slowing down disease progression in pre-clinical animal studies, while only one has subsequently been proven to effectively slow down disease progression in patients, and it has recently been approved for therapy in Europe, Canada and Japan. Among the affected cellular functions and pathways, recent investigations have described metabolic derangement in ADPKD as a major trait offering additional opportunities for targeted therapies. In particular, increased aerobic glycolysis (the Warburg effect) has been described as a prominent feature of ADPKD kidneys and its inhibition using the glucose analogue 2-deoxy-D-glucose (2DG) proved effective in slowing down disease progression in preclinical models of the disease. At the same time, previous clinical experiences have been reported with 2DG, showing that this compound is well tolerated in humans with minimal and reversible side effects. In this work, we review the literature and speculate that 2DG could be a good candidate for a clinical trial in humans affected by ADPKD.

2-Deoxy-D-glucose enhances dichloroacetate antitumor action against Lewis lung carcinoma

Aerobic glycolysis that supports high proliferation rate and survival of tumor cells in unfavorable conditions is among fundamental features of tumor metabolism. The search for active modulators of energetic metabolism capable of suppressing tumor growth and metastasis could result in higher effectiveness of anticancer therapy.

AIM

To study antitumor and antimetastatic activity of the modulators of energetic metabolism dichloroacetate (DCA) and 2-deoxy-D-glucose (2DG) used in combination treatment of Lewis lung carcinoma (LLC).

MATERIALS AND METHODS

As experimental tumor model, LLC/R9 variant was used. DCA and 2DG were administered per os to С57Bl/6 mice 5 times per week for 3 weeks at a total dose of 1.5 and 0.98 g/kg, respectively, as single agents or in combination starting from the following day after tumor cell transplantation. Growth of primary tumor and number and volume of lung metastases were registered. Lactate and pyruvate content was determined by enzymatic methods using lactate dehydrogenase. Electron paramagnetic resonance was used for analyzing the functional state of the components of mitochondrial respiratory chain. Engulfing activity and reactive oxygen species (ROS) production in tumor-associated CD14(+) cells was analyzed by flow cytometer with the use of FITC-labeled staphylococcus, and by spectrofluorometry with the use of 2.7-dichlorofluorescein diacetate, respectively.

RESULTS

DCA administered as a single agent did not affect primary tumor growth but decreased the number and volume of lung metastases by 60% (p < 0.05) and 90% (p < 0.05), respectively. In mice treated with 2DG only, primary tumor volume as well as the number and volume of lung metastases were not affected. Combination treatment with DCA and 2DG resulted in the decrease of primary tumor volume, the number and volumes of lung metastases by 70; 46, and 90%, respectively (p < 0.05). High antitumor activity of DCA + 2DG was associated with 31% decrease (p < 0.05) of lactate content in tumor tissue and 120% increase (p < 0.01) of ROS production in CD14(+) cells recruited to the region of tumor growth.

CONCLUSION

2DG that possesses neither antitumor nor antimetastatic activity against LLC/R9 significantly enhanced antitumor activity of DCA with accompanying inhibition of glycolysis and increase of cytotoxic activity of CD14(+) cells infiltrating tumor tissue. Taking into account significant antimetastatic activity of DCA this substance could be considered as a promising antimetastatic agent.

mTORC1-Dependent Metabolic Reprogramming Underlies Escape from Glycolysis Addiction in Cancer Cells

Although glycolysis is substantially elevated in many tumors, therapeutic targeting of glycolysis in cancer patients has not yet been successful, potentially reflecting the metabolic plasticity of tumor cells. In various cancer cells exposed to a continuous glycolytic block, we identified a recurrent reprogramming mechanism involving sustained mTORC1 signaling that underlies escape from glycolytic addiction. Active mTORC1 directs increased glucose flux via the pentose phosphate pathway back into glycolysis, thereby circumventing a glycolysis block and ensuring adequate ATP and biomass production. Combined inhibition of glycolysis and mTORC1 signaling disrupted metabolic reprogramming in tumor cells and inhibited their growth in vitro and in vivo. These findings reveal novel combinatorial therapeutic strategies to realize the potential benefit from targeting the Warburg effect.

Preventing Allograft Rejection by Targeting Immune Metabolism

Upon antigen recognition and co-stimulation, T lymphocytes upregulate the metabolic machinery necessary to proliferate and sustain effector function. This metabolic reprogramming in T cells regulates T cell activation and differentiation but is not just a consequence of antigen recognition. Although such metabolic reprogramming promotes the differentiation and function of T effector cells, the differentiation of regulatory T cells employs different metabolic reprogramming. Therefore, we hypothesized that inhibition of glycolysis and glutamine metabolism might prevent graft rejection by inhibiting effector generation and function and promoting regulatory T cell generation. We devised an anti-rejection regimen involving the glycolytic inhibitor 2-deoxyglucose (2-DG), the anti-type II diabetes drug metformin, and the inhibitor of glutamine metabolism 6-diazo-5-oxo-L-norleucine (DON). Using this triple-drug regimen, we were able to prevent or delay graft rejection in fully mismatched skin and heart allograft transplantation models.

Chronic Dietary Administration of the Glycolytic Inhibitor 2-Deoxy-D-Glucose (2-DG) Inhibits the Growth of Implanted Ehrlich's Ascites Tumor in Mice

Background

Dietary energy restriction (DER) has been well established as a potent anticancer strategy. Non-adoption of restricted diet for an extended period has limited its practical implementation in humans with a compelling need to develop agents that mimic effects similar to DER, without reduction in actual dietary intake. Glycolytic inhibitor, 2-deoxy-D-glucose (2-DG), has recently been shown to possess potential as an energy restriction mimetic agent (ERMA). In the present study we evaluated the effect of dietary 2-DG administration on a mouse tumor model, with a focus on several potential mechanisms that may account for the inhibition of tumorigenesis.

Methodology/Principal Findings

Swiss albino strain ‘A’ mice were administered with 0.2% and 0.4% w/v 2-DG in drinking water for 3 months prior to tumor implantation (Ehrlich’s ascites carcinoma; EAC) and continued till the termination of the study with no adverse effects on general physiology and animal growth. Dietary 2-DG significantly reduced the tumor incidence, delayed the onset, and compromised the tumor growth along with enhanced survival. We observed reduced blood glucose and serum insulin levels along with decreased proliferating cell nuclear antigen (PCNA) and bromodeoxyuridine positive (BrdU⁺) tumor cells in 2-DG fed mice. Also, reduced levels of certain key players of metabolic pathways such as phosphatidylinositol 3-kinase (PI3K), phosphorylated-Akt and hypoxia inducible factor-1 alpha (HIF-1α) were also noted in tumors of 2-DG fed mice. Further, decrease in CD4⁺/CD8⁺ ratio and T-regulatory cells observed in 2-DG fed mice suggested enhanced antitumor immunity and T cell effector function.

Conclusion/Significance

These results strongly suggest that dietary 2-DG administration in mice, at doses easily achievable in humans, suitably modulates several pleotrophic factors mimicking DER and inhibits tumorigenesis, emphasizing the use of ERMAs as a promising cancer preventive strategy.

mTORC1 and mTORC2 selectively regulate CD8⁺ T cell differentiation

Activation of mTOR-dependent pathways regulates the specification and differentiation of CD4+ T effector cell subsets. Herein, we show that mTOR complex 1 (mTORC1) and mTORC2 have distinct roles in the generation of CD8+ T cell effector and memory populations. Evaluation of mice with a T cell-specific deletion of the gene encoding the negative regulator of mTORC1, tuberous sclerosis complex 2 (TSC2), resulted in the generation of highly glycolytic and potent effector CD8+ T cells; however, due to constitutive mTORC1 activation, these cells retained a terminally differentiated effector phenotype and were incapable of transitioning into a memory state. In contrast, CD8+ T cells deficient in mTORC1 activity due to loss of RAS homolog enriched in brain (RHEB) failed to differentiate into effector cells but retained memory characteristics, such as surface marker expression, a lower metabolic rate, and increased longevity. However, these RHEB-deficient memory-like T cells failed to generate recall responses as the result of metabolic defects. While mTORC1 influenced CD8+ T cell effector responses, mTORC2 activity regulated CD8+ T cell memory. mTORC2 inhibition resulted in metabolic reprogramming, which enhanced the generation of CD8+ memory cells. Overall, these results define specific roles for mTORC1 and mTORC2 that link metabolism and CD8+ T cell effector and memory generation and suggest that these functions have the potential to be targeted for enhancing vaccine efficacy and antitumor immunity.

Normalization of CD4+ T cell metabolism reverses lupus

Systemic lupus erythematosus (SLE) is an autoimmune disease in which autoreactive CD4(+) T cells play an essential role. CD4(+) T cells rely on glycolysis for inflammatory effector functions, but recent studies have shown that mitochondrial metabolism supports their chronic activation. How these processes contribute to lupus is unclear. We show that both glycolysis and mitochondrial oxidative metabolism are elevated in CD4(+) T cells from lupus-prone B6.Sle1.Sle2.Sle3 (TC) mice as compared to non-autoimmune controls. In vitro, both the mitochondrial metabolism inhibitor metformin and the glucose metabolism inhibitor 2-deoxy-d-glucose (2DG) reduced interferon-γ (IFN-γ) production, although at different stages of activation. Metformin also restored the defective interleukin-2 (IL-2) production by TC CD4(+) T cells. In vivo, treatment of TC mice and other lupus models with a combination of metformin and 2DG normalized T cell metabolism and reversed disease biomarkers. Further, CD4(+) T cells from SLE patients also exhibited enhanced glycolysis and mitochondrial metabolism that correlated with their activation status, and their excessive IFN-γ production was significantly reduced by metformin in vitro. These results suggest that normalization of T cell metabolism through the dual inhibition of glycolysis and mitochondrial metabolism is a promising therapeutic venue for SLE.

Enhanced antitumor immunity contributes to the radio-sensitization of ehrlich ascites tumor by the glycolytic inhibitor 2-deoxy-D-glucose in mice

Two-deoxy-D-glucose (2-DG), an inhibitor of glycolysis differentially enhances the radiation and chemotherapeutic drug induced cell death in cancer cells in vitro, while the local tumor control (tumor regression) following systemic administration of 2-DG and focal irradiation of the tumor results in both complete (cure) and partial response in a fraction of the tumor bearing mice. In the present studies, we investigated the effects of systemically administered 2-DG and focal irradiation of the tumor on the immune system in Ehrlich ascites tumor (EAT) bearing Strain "A" mice. Markers of different immune cells were analyzed by immune-flow cytometry and secretary cytokines by ELISA, besides monitoring tumor growth. Increase in the expression of innate (NK and monocytes) and adaptive CD4+cells, and a decrease in B cells (CD19) have been observed after the combined treatment, suggestive of activation of anti-tumor immune response. Interestingly, immature dendritic cells were found to be down regulated, while their functional markers CD86 and MHC II were up regulated in the remaining dendritic cells following the combination treatment. Similarly, decrease in the CD4(+) naïve cells with concomitant increase in activated CD4+ cells corroborated the immune activation. Further, a shift from Th2 and Th17 to Th1 besides a decrease in inflammatory cytokines was also observed in the animals showing complete response (cure; tumor free survival). This shift was also complimented by respective antibody class switching followed by the combined treatment. The immune activation or alteration in the homeostasis favoring antitumor immune response may be due to depletion in T regulatory cells (CD4(+)CD25(+)FoxP3(+)). Altogether, these results suggest that early differential immune activation is responsible for the heterogenous response to the combined treatment. Taken together, these studies for the first time provided insight into the additional mechanisms underlying radio-sensitization by 2-DG in vivo by unraveling its potential as an immune-modulator besides direct effects on the tumor.

[2-Deoxy-D-glucose combined with Taxol inhibits VEGF expression and induces apoptosis in orthotopically transplanted breast cancer in C3H mice]

OBJECTIVE

To investigate the antineoplastic effects of 2-Deoxy-D-glucose (2-DG) combined with Taxol on orthotopically transplanted breast cancer in C3H mice and explore the mechanism.

METHODS

C3H mice bearing orthotopically transplanted breast cancer xenograft were randomly divided into 4 groups, namely the control group, 2-DG group, Taxol group, and 2-DG+Taxol group. The corresponding drugs were administered intraperitoneally every 3 days for 18 consecutive days, and the tumor volume was measured every 3 days to draw the tumor growth curve. The mice were then sacrificed to measure the tumor weight on day 19 and examine tumor cell apoptosis with TUNEL assay and VEGF expression using immunohistochemistry.

RESULTS

2-DG combined with Taxol obviously suppressed the tumor growth with a tumor inhibition rate of 66.06% as compared to the rate of 36.97% in Taxol group. The combined treatment also caused more obvious cell apoptosis and significantly reduced VEGF expression in the tumor cells as compared with the other groups.

CONCLUSION

2-DG can enhance the inhibitory effect of Taxol on orthotopically transplanted breast cancer xenograft in C3H mice probably by inducing tumor cell apoptosis and lowering VEGF expressions.

Pharmacokinetic and toxicological evaluation of multi-functional thiol-6-fluoro-6-deoxy-D-glucose gold nanoparticles in vivo

We synthesized a novel, multi-functional, radiosensitizing agent by covalently linking 6-fluoro-6-deoxy-D-glucose (6-FDG) to gold nanoparticles (6-FDG-GNPs) via a thiol functional group. We then assessed the bio-distribution and pharmacokinetic properties of 6-FDG-GNPs in vivo using a murine model. At 2 h, following intravenous injection of 6-FDG-GNPs into the murine model, approximately 30% of the 6-FDG-GNPs were distributed to three major organs: the liver, the spleen and the kidney. PEGylation of the 6-FDG-GNPs was found to significantly improve the bio-distribution of 6-FDG-GNPs by avoiding unintentional uptake into these organs, while simultaneously doubling the cellular uptake of GNPs in implanted breast MCF-7 adenocarcinoma. When combined with radiation, PEG-6-FDG-GNPs were found to increase the apoptosis of the MCF-7 breast adenocarinoma cells by radiation both in vitro and in vivo. Pharmacokinetic data indicate that GNPs reach their maximal concentrations at a time window of two to four hours post-injection, during which optimal radiation efficiency can be achieved. PEG-6-FDG-GNPs are thus novel nanoparticles that preferentially accumulate in targeted cancer cells where they act as potent radiosensitizing agents. Future research will aim to substitute the (18)F atom into the 6-FDG molecule so that the PEG-6-FDG-GNPs can also function as radiotracers for use in positron emission tomography scanning to aid cancer diagnosis and image guided radiation therapy planning.

Potential for use of 1,5-anhydroglucitol when initiating insulin therapy in people with type 2 diabetes and suboptimal control with oral antidiabetic drugs

Endpoint HbA(1c) <7.0% was achieved by 80 (73.4%) lispro mix 25 (LM25)-treated patients and 67 (60.9%) glargine-treated patients (p=0.027) with baseline 1,5 anhydroglucitol (1,5AG) below median and 75 (70.8%) LM25-treated patients and 72 (63.7%) glargine-treated patients (p=0.238) with 1,5AG≥median, suggesting, 1,5AG may offer therapeutic insight when starting insulin therapy.

2-Deoxy-D-glucose treatment induces ketogenesis, sustains mitochondrial function, and reduces pathology in female mouse model of Alzheimer's disease

Previously, we demonstrated that mitochondrial bioenergetic deficits preceded Alzheimer's disease (AD) pathology in the female triple-transgenic AD (3xTgAD) mouse model. In parallel, 3xTgAD mice exhibited elevated expression of ketogenic markers, indicating a compensatory mechanism for energy production in brain. This compensatory response to generate an alternative fuel source was temporary and diminished with disease progression. To determine whether this compensatory alternative fuel system could be sustained, we investigated the impact of 2-deoxy-D-glucose (2-DG), a compound known to induce ketogenesis, on bioenergetic function and AD pathology burden in brain. 6-month-old female 3xTgAD mice were fed either a regular diet (AIN-93G) or a diet containing 0.04% 2-DG for 7 weeks. 2-DG diet significantly increased serum ketone body level and brain expression of enzymes required for ketone body metabolism. The 2-DG-induced maintenance of mitochondrial bioenergetics was paralleled by simultaneous reduction in oxidative stress. Further, 2-DG treated mice exhibited a significant reduction of both amyloid precursor protein (APP) and amyloid beta (Aβ) oligomers, which was paralleled by significantly increased α-secretase and decreased γ-secretase expression, indicating that 2-DG induced a shift towards a non-amyloidogenic pathway. In addition, 2-DG increased expression of genes involved in Aβ clearance pathways, degradation, sequestering, and transport. Concomitant with increased bioenergetic capacity and reduced β-amyloid burden, 2-DG significantly increased expression of neurotrophic growth factors, BDNF and NGF. Results of these analyses demonstrate that dietary 2-DG treatment increased ketogenesis and ketone metabolism, enhanced mitochondrial bioenergetic capacity, reduced β-amyloid generation and increased mechanisms of β-amyloid clearance. Further, these data link bioenergetic capacity with β-amyloid generation and demonstrate that β-amyloid burden was dynamic and reversible, as 2-DG reduced activation of the amyloidogenic pathway and increased mechanisms of β-amyloid clearance. Collectively, these data provide preclinical evidence for dietary 2-DG as a disease-modifying intervention to delay progression of bioenergetic deficits in brain and associated β-amyloid burden.

2-Deoxy-D-glucose reverses the Indian red scorpion venom-induced cardiopulmonary abnormalities in anesthetized rats

Role of 2-Deoxy-D-glucose (2-DG) in reversing the Indian red scorpion (Mesobuthus tamulus concanesis Pocock, MBT) venom-induced toxicity was examined. Femoral arterial pressure, ECG and respiratory movements were recorded in urethane anesthetized rats. Plasma glucose and serum insulin levels were also estimated. Intravenous injection of 5 mg/kg MBT venom produced immediate decrease in mean arterial pressure, heart rate and respiratory frequency followed by an increase and subsequent progressive decrease. ECG pattern exhibited ischaemic changes. There was hyperinsulinemia after venom without corresponding decrease in plasma glucose. The animals died within 37 +/- 9 min and demonstrated significant increase in pulmonary water content. 2-DG pretreatment (0.5 g/kg, iv) improved the cardiopulmonary abnormalities induced by venom and the animals survived for nearly 120 min. There was no hyperinsulinemia and increased pulmonary water content in these animals. In insulin (2 IU/kg) treated rats, the MBT venom-induced cardiopulmonary abnormalities were attenuated and ECG abnormalities were reversed. The pulmonary water content in these animals exhibited a decreasing trend and the animals survived for 120 min. Repaglinide (10 microg/kg, iv) pretreatment failed to reverse the venom-induced cardiopulmonary changes including the increased pulmonary water content. The survival time was similar to venom only group. The present results reveal that 2-DG reverses the venom-induced cardiopulmonary toxicity probably by restoring insulin sensitivity.

Targeting tumor metabolism with 2-deoxyglucose in patients with castrate-resistant prostate cancer and advanced malignancies

BACKGROUND

A profound difference between cancer and normal tissues is the preferential utilization of glycolysis by cancer cells. To translate this paradigm in the clinic, we completed a phase I study of 2-deoxyglucose (2DG), and assessed 2DG uptake with fluorodeoxyglucose (FDG) positron emission tomography (PET) and the autophagy substrate p62 as a marker of 2DG resistance.

METHODS

Patients received 2DG orally on days 1-14 of a 21-day cycle in cohorts of three in a dose-escalating manner. Correlative assessments included PET scans at baseline and day 2 and p62 protein in peripheral blood mononuclear cells as a potential marker of 2DG resistance.

RESULTS

The dose of 45 mg/kg was defined as the recommended phase II dose, secondary to dose-limiting toxicity of grade 3 asymptomatic QTc prolongation at a dose of 60 mg/kg. PK evaluation of 2DG revealed linear pharmacokinetics with C(max) 45 microg/ml (277 microM), 73.7 microg/ml (449 microM), and 122 microg/ml (744 microM) in dose levels 30, 45, and 60 mg/kg, respectively. Five of eight patients assessed with FDG-PET scanning demonstrated decreased FDG uptake by day 2 of therapy, suggesting competition of 2DG with FDG. Five of six patients assessed for p62 had a decrease in p62 at 24 hr.

CONCLUSIONS

These data support the safety of 2DG, defined 2DG PK, demonstrated the effect of 2DG on FDG-PET imaging, and demonstrated the feasibility of assessment of p62 as an autophagic resistance marker. These data support future studies of 2DG alone or in combination with approaches to abrogate autophagy.

From delocalized lipophilic cations to hypoxia: blocking tumor cell mitochondrial function leads to therapeutic gain with glycolytic inhibitors

An unexpected similarity between cancer and cardiac muscle cells in their sensitivity to anthracyclines and delocalized lipophilic cations (DLC) prompted a series of studies in which it was shown that the positive charge of these compounds is central to their selective accumulation and toxicity in these two distinct cell types. An initial finding to explain this phenomenon was that cancer and cardiac muscle cells exhibit high negative plasma membrane potentials resulting in increased uptake of these agents. However, the p-glycoprotein efflux pump was shown to be another factor underlying differential accumulation of these compounds, since it recognizes positively charged drugs and thereby actively reduces their intracellular concentrations. The delocalized positive charge and lipophilicity of DLCs leads to their retention and inhibition of ATP synthesis in mitochondria. Years later it was realized that cancer cells in the hypoxic portions of solid tumors were similar to those treated with DLCs in relying mainly on anaerobic metabolism for survival and could thus be targeted with a glycolytic inhibitor, 2-deoxy-D-glucose (2-DG). This hypothesis has lead to a Phase I clinical trial in which 2-DG is used to selectively kill the hypoxic tumor cell population which are resistant to standard chemotherapy or radiation.

2-Deoxyglucose combined with wild-type p53 overexpression enhances cytotoxicity in human prostate cancer cells via oxidative stress

Overexpression of the tumor suppressor gene, wild-type p53 (wtp53), using adenoviral vectors (Adp53) has been suggested to kill cancer cells by hydroperoxide-mediated oxidative stress [1,2] and nutrient distress induced by the glucose analog, 2-deoxyglucose (2DG), has been suggested to enhance tumor cell killing by agents that induce oxidative stress via disrupting hydroperoxide metabolism [3,4]. In the current study clonogenic cell killing of PC-3 and DU-145 human prostate cancer cells (lacking functional p53) mediated by 4 h exposure to 50 plaque forming units (pfus)/cell of Adp53 (that caused the enforced overexpression of wtp53) was significantly enhanced by treatment with 2DG. Accumulation of glutathione disulfide was found to be significantly greater in both cell lines treated with 2DG+Adp53 and both cell lines treated with 2DG+Adp53 showed a approximately 2-fold increases in dihydroethidine (DHE) and 5-(and-6)-carboxy-2',7'-dichlorodihydrofluorescein diacetate (CDCFH(2)) oxidation, indicative of increased steady-state levels of O(2)(.-) and hydroperoxides, respectively. Finally, overexpression of catalase or glutathione peroxidase using adenoviral vectors partially, but significantly, protected DU-145 cells from the toxicity induced by 2DG+Adp53 treatment. These results show that treatment of human prostate cancer cells with the combination of 2DG (a nutrient stress) and overexpression of the tumor suppressor gene, wtp53, enhances clonogenic cell killing by a mechanism that involves oxidative stress as well as allowing for the speculation that inhibitors of glucose and hydroperoxide metabolism can be used in combination with Adp53 gene therapy to enhance therapeutic responses.

Combining radioimmunotherapy with antihypoxia therapy 2-deoxy-D-glucose results in reduction of therapeutic efficacy

PURPOSE

The efficacy of solid tumor radioimmunotherapy is reduced by heterogeneous tumor distribution of the radionuclide, with dose mainly deposited in the normoxic region and by the relative radioresistance of hypoxic tumor cells. In an attempt to overcome these challenges, radioimmunotherapy was combined with 2-deoxy-d-glucose (2DG), a hypoxia-selective cytotoxic inhibitor of glucose metabolism.

EXPERIMENTAL DESIGN

In vitro toxicity of 2DG in LS174T cultures was tested using a colony-forming assay. The effect of combining 2DG with radioimmunotherapy in vivo was tested by administering radiolabeled anti-carcinoembryonic antigen antibody ([(131)I]A5B7 IgG1 whole monoclonal) to nude mice bearing s.c. LS174T tumors, followed by 10 daily injections of 2DG (2.0 g/kg). Tumors were measured to assess therapeutic efficacy.

RESULTS

Data from in vitro studies confirmed 2DG cytotoxicity in this cell line. Greater toxicity was observed under standard laboratory conditions and in hypoxic cultures than at intermediate, physiologically relevant levels of glucose and oxygen. Alone, 2DG had no effect on in vivo tumor growth (P = 0.377 compared with saline-treated controls). Combination of radioimmunotherapy with 2DG reduced the therapeutic effect of radioimmunotherapy (e.g., 150 microCi (131)I alone mean survival time, 48.33 +/- 16.83 days; combined with 2DG, 30.67 +/- 5.62 days, P = 0.038).

CONCLUSIONS

The combination investigated had a detrimental effect on survival. It is suggested that a cellular metabolic response to more aggressive therapy, previously reported in vitro, caused this. The results of this study have implications for the clinical application of combined cancer therapies with an antimetabolic modality component.

2-Deoxyglucose: An anticancer and antiviral therapeutic, but not any more a low glucose mimetic

2-Deoxyglucose (2-DG), a non-metabolizable glucose analogue, blocks glycolysis and inhibits protein glycosylation. It has been tested in multiple studies for possible application as an anticancer or antiviral therapeutic. The inhibitory effect of 2-DG on ATP generation made it a good candidate molecule as a calorie restriction mimetic as well. Furthermore, 2-DG has been utilized in numerous studies to simulate a condition of glucose starvation. Because 2-DG disrupts glucose metabolism, protein glycosylation, and ER quality control at the same time, a cellular or pathologic outcome could be easily misinterpreted without clear understanding of 2-DG's effect on each of these aspects. However, the effect of 2-DG on protein glycosylation has rarely been investigated. A recent study suggested that 2-DG causes hyperGlcNAcylation of proteins, while low glucose supply causes hypoGlcNAcylation. In certain aspects of cellular physiology, this difference could be disregarded, but in others, this may possibly cause totally different outcomes.

Redox ratio of mitochondria as an indicator for the response of photodynamic therapy

The effect of photodynamic therapy (PDT) treatment on the metabolic state of tumor mitochondria is investigated by imaging of tumor redox status. PDT is performed using the photosensitizer pyropheophorbide-2-deoxyglucosamide (Pyro-2DG), which utilizes the glucose import pathway. It is found that Pyro-2DG-induced PDT resulting in a highly oxidized state of tumor mitochondria. This is determined from the redox ratio changes derived from the intrinsic oxidized flavoprotein (Fp) and reduced pyridine nucleotide (PN) [i.e., reduced nicotinamide adenine dinucleotide (NADH)] fluorescence signals observed using a cryoimager. Thus, the redox ratio is a sensitive indicator for providing reliable and informative measurements of PDT-induced tissue damage. In the PDT treated region of the tumor, highly oxidized flavoprotein and diminishing NADH fluorescence is detected, suggesting that flavoprotein and NADH are oxidized by singlet oxygen produced in the photosensitization process.

Caloric restriction in primates and relevance to humans

Dietary caloric restriction (CR) is the only intervention conclusively and reproducibly shown to slow aging and maintain health and vitality in mammals. Although this paradigm has been known for over 60 years, its precise biological mechanisms and applicability to humans remain unknown. We began addressing the latter question in 1987 with the first controlled study of CR in primates (rhesus and squirrel monkeys, which are evolutionarily much closer to humans than the rodents most frequently employed in CR studies). To date, our results strongly suggest that the same beneficial "antiaging" and/or "antidisease" effects observed in CR rodents also occur in primates. These include lower plasma insulin levels and greater sensitivity; lower body temperatures; reduced cholesterol, triglycerides, blood pressure, and arterial stiffness; elevated HDL; and slower age-related decline in circulating levels of DHEAS. Collectively, these biomarkers suggest that CR primates will be less likely to incur diabetes, cardiovascular problems, and other age-related diseases and may in fact be aging more slowly than fully fed counterparts. Despite these very encouraging results, it is unlikely that most humans would be willing to maintain a 30% reduced diet for the bulk of their adult life span, even if it meant more healthy years. For this reason, we have begun to explore CR mimetics, agents that might elicit the same beneficial effects as CR, without the necessity of dieting. Our initial studies have focused on 2-deoxyglucose (2DG), a sugar analogue with a limited metabolism that actually reduces glucose/energy flux without decreasing food intake in rats. In a six-month pilot study, 2DG lowered plasma insulin and body temperature in a manner analagous to that of CR. Thus, metabolic effects that mediate the CR mechanism can be attained pharmacologically. Doses were titrated to eliminate toxicity; a long-term longevity study is now under way. In addition, data from other laboratories suggest that at least some of the same physiological/metabolic end points that are associated with the beneficial effects of underfeeding may be obtained from other potential CR mimetic agents, some naturally occurring in food products. Much work remains to be done, but taken together, our successful results with CR in primates and 2DG administration to rats suggest that it may indeed be possible to obtain the health- and longevity-promoting effects of the former intervention without actually decreasing food intake.

2-deoxyglucose enhances epileptic tolerance evoked by transient incomplete brain ischemia in mice

The aim of the study was to assess the influence of chronic treatment with a non-metabolisable glucose analogue, 2-deoxyglucose (2-DG) at a 150 mg/kg dose on long-term epileptic tolerance (ET) evoked by 30 min bilateral carotid artery clamping (BCCA) in mice. The effects of protein synthesis inhibition with cycloheximide (CHX), given in three daily doses of 2.5 mg/kg starting either 1 day before (peri-insult regimen) or 1 day after the priming insult (post-insult regimen), on ET development was also studied. Seizures were induced 14 days after BCCA with 3.5 mg/kg of bicuculline; this dose (CD97) evokes convulsions in 97% of normal untreated mice. BCCA resulted in decreased mortality, prolonged latency to the onset of generalised convulsions and decreased overall seizure score. CHX given in the post-insult regimen did not influence, while the peri-insult regimen abolished, all signs of BCCA-evoked ET. 2-DG treatment of sham-operated animals resulted in a moderate but significant decrease in mortality rate and a tendency toward a lower seizure score. BCCA combined with 2-DG treatment resulted in a marked decrease in mortality rate, as well as reduction in all indicators of seizure susceptibility. CHX abolished the antiepileptic effects of BCCA alone, as well as BCCA combined with 2-DG, while it did not influence the 2-DG-related decrease in mortality. We conclude that the development of BCCA-induced epileptic tolerance, as well as unmasking antiepileptic effects of 2-DG by BCCA, is dependent on protein synthesis.

In vivo 2-deoxyglucose administration preserves glucose and glutamate transport and mitochondrial function in cortical synaptic terminals after exposure to amyloid beta-peptide and iron: evidence for a stress response

Mild metabolic stress can increase resistance of neurons in the brain to subsequent more severe insults, as exemplified by the beneficial effects of heat shock and ischemic preconditioning. Studies of Alzheimer's disease and other age-related neurodegenerative disorders indicate that dysfunction and degeneration of synapses occur early in the cell death process, and that oxidative stress and mitochondrial dysfunction are central events in this pathological process. It was recently shown that administration of 2-deoxy-d-glucose (2DG), a nonmetabolizable glucose analog that induces metabolic stress, to rats and mice can increase resistance of neurons in the brain to excitotoxic, ischemic, and oxidative injury. We now report that administration of 2DG to adult rats (daily i.p. injections of 100 mg/kg body weight) increases resistance of synaptic terminals to dysfunction and degeneration induced by amyloid beta-peptide and ferrous iron, an oxidative insult. The magnitude of impairment of glucose and glutamate transport induced by amyloid beta-peptide and iron was significantly reduced in cortical synaptosomes from 2DG-treated rats compared to saline-treated control rats. Mitochondrial dysfunction, as indicated by increased levels of reactive oxygen species and decreased transmembrane potential, was significantly attenuated after exposure to amyloid beta-peptide and iron in synaptosomes from 2DG-treated rats. Levels of the stress proteins HSP-70 and GRP-78 were increased in synaptosomes from 2DG-treated rats, suggesting a mechanism whereby 2DG protects synaptic terminals. We conclude that 2DG bolsters cytoprotective mechanisms within synaptic terminals, suggesting novel preventative and therapeutic approaches for neurodegenerative disorders.

Dietary restriction and 2-deoxyglucose administration reduce focal ischemic brain damage and improve behavioral outcome: evidence for a preconditioning mechanism

Stroke, an age-related disorder involving degeneration of neurons resulting from cerebral ischemia, is a major cause of disability and mortality. Although dietary restriction (DR) extends lifespan and reduces levels of cellular oxidative stress in several different organ systems including the brain, the impact of DR on ischemic brain injury is unknown. We report that maintenance of adult rats on a DR regimen resulted in reduced brain damage and improved behavioral outcome in a middle cerebral artery occlusion-reperfusion (MCAO-R) stroke model. Administration of 2-deoxyglucose (2-DG), a nonmetabolizable analogue of glucose, to rats fed ad libitum resulted in reduced ischemic brain damage and improved behavioral outcome following MCAO-R. 2-DG protected cultured hippocampal neurons against chemical hypoxia, demonstrating a direct protective action on neurons. DR and 2-DG administration resulted in an increase in the level of the stress protein heat-shock protein 70 (HSP-70) in striatal cells in vivo, and 2-DG treatment induced HSP-70 in cultured neurons suggesting involvement of a preconditioning stress response in the neuroprotective actions of DR and 2-DG. The neuroprotective effect of DR and 2-DG in this focal cerebral ischemia model suggests that outcome following stroke may be improved in individuals who follow a regimen of reduced food intake.

Optimizing radiation therapy of brain tumours by combination of 5-bromo-2-deoxy-uridine & 2-deoxy-D-glucose

The effects of 5-bromo-2-deoxy-uridine (BrdU) and 2-deoxy-D-glucose (2-DG) on 60Co-gamma ray induced damage were studied in a human glioma cell line grown as monolayer. Radiation induced micronuclei formation was used as an index of cytogenetic damage. Exponentially growing cells (doubling time 16-20 h) were incubated in the presence of BrdU (0.8 microM, in dark) for 24 h. After removing BrdU, cells were irradiated (1-4 Gy), incubated with or without 2-DG (2-3 h), and grown further (for 18, 24, 30 or 45 h) for assay of damage. It was observed that (i) BrdU and 2-DG treatments did not induce micronuclei formation in unirradiated cultures; (ii) pre-irradiation presence of BrdU increased the gamma-ray induced micronuclei formation; (iii) incubation of irradiated cells under sub-optimal growth conditions [Dulbecco's modified minimal essential medium (DMEM) + 1% serum, or DMEM alone] instead of growth medium (DMEM + 5% serum) progressively decreased micronuclei formation; and (iv) post-irradiation presence of 2-DG (1.25, 2.5, 5 mM, 2-3 h in DMEM + 1% serum) enhanced the radiation damage with and without BrdU treatment at all the time points studied. These observations suggest that (i) radiation induced lesions leading to micronuclei formation in proliferating cells are, at least, partly repairable; (ii) the presence of 2-DG (2DG/glucose > or = 0.25) for short intervals (approximately 2 h), could enhance radiation damage in proliferating brain tumour cells, in the absence as well as presence of BrdU incorporation; and (iii) the combination of 2-DG could reduce BrdU doses required for radiosensitization of brain tumours, reducing, thereby, its toxic side effects.

Cytotoxic action of 2-deoxy-D-glucose tetraacetate in tumoral pancreatic islet cells

Tumoral insulin-producing cells of the RINm5F line were cultured for 8-96 h in the absence or presence of 2-deoxy-D-glucose (0.15-0.80 mM) or its tetraacetate ester (0.08-0.80 mM). Despite the fact that over a short incubation of 120 min the utilization of D-[5-3H]glucose and oxidation of D-[U-14C]glucose were not more markedly decreased by 2-deoxy-D-glucose tetraacetate than by the unesterified glucose analogue, the growth of the tumoral cells, as assessed by either the generation of formazan from 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide or direct cell counting, was more severely affected by the ester than by 2-deoxy-D-glucose. At a high concentration (0.80 mM), the ester even decreased the cell number below its initial value. No restoration of cell growth was observed when the cells were exposed for only 8 h to 2-deoxy-D-glucose tetraacetate (0.80 mM) and then further cultured for 64 h in the absence of the ester. These findings indicate that such an ester acts as a powerful cytostatic and cytotoxic agent in this tumoral cell line.

Role of nuclear magnetic resonance spectroscopy (MRS) in cancer diagnosis and treatment: 31P, 23Na, and 1H MRS studies of three models of pancreatic cancer

The role of nuclear magnetic resonance spectroscopy (MRS) in pancreatic cancer diagnosis and its treatment were assessed in three models of pancreatic neoplasms. Perfused MIA PaCa-2 human pancreatic cancer cells, s.c. implanted pancreatic tumors in hamsters, and pancreatic tumors induced in situ in rats by direct application of the carcinogen 7,12-dimethyl benzanthracene, were studied by phosphorous ((31)P), sodium ((23)Na), and proton ((1)H) MRS. (31)P spectra of pancreatic cancer were qualitatively similar to those of intact organs. There were, however, variations in peak intensities and ratios. Phosphomonoester signals were prominent in both normal pancreases and tumors, but their levels depended on the proliferation rate and on environmental conditions. Thus, the phosphomonoester:beta-nucleoside triphosphate ratio was 1.15 +/- 0.32 in 90% confluency and 1.31 +/- 0.43 in 70% confluency, and this ratio increased upon lowering the perfusion rate. Total (intra- and extracellular) sodium concentrations, measured in the solid tumors, were 39-40 micromol/g wet weight in normal pancreases. Contrary to a previous hypothesis that malignant transformation is associated with increased sodium content, our (23)Na MRS data showed that there were no significant differences between pancreatic tumors and intact organs. Proton spectra of perchloric acid extracts revealed several differences between tumors and control pancreases. The principal findings were elevated levels of the amino acid taurine, from 1.17 +/- 0.39 micromol/g wet weight in healthy pancreases, to 2.79 +/- 0.71 micromol/g wet weight in pancreatic carcinoma in rats, and lactate levels that increased from 0.92 +/- 0.2 to 6.19 +/- 1.93 micromol/g wet weight, respectively. On the other hand, creatine and glutamate were higher in the normal pancreases. Pancreatic cancer is usually resistant to chemotherapy, and we evaluated the effects of the metabolic inhibitors 2-deoxyglucose and lonidamine on the human pancreatic cancer cells by MRS and cytotoxicity studies. The IC50 of Adriamycin and 2-deoxyglucose were 1.49 +/- 0.18 x 10(6) and 136 +/- 17 microg/ml, respectively. These results were similar to data obtained previously in multidrug-resistant human breast cancer cells, which were highly resistant (33-fold) to Adriamycin but were more susceptible (9-fold) to 2-deoxyglucose than their parental cells.

Perchloroethylene-induced alterations in glucose metabolism and their prevention by 2-deoxy-D-glucose and vitamin E in mice

The effect of 2-deoxy-D-glucose (2DG) and vitamin E on the alterations in glucose metabolism induced by perchloroethylene (PER) was studied in mice. Oral administration of PER (3 g kg-1 body wt. day-1) in sesame oil for 15 days caused a significant increase in liver weight, degeneration/necrosis of hepatocytes and increase in kidney weight, glomerular nephrosis and degeneration. These changes occurred concurrently with a significant decrease in blood glucose level, elevated activities of hexokinase, aldolase and phosphoglucoisomerase and decreased activity of gluconeogenic enzymes (glucose-6-phosphatase and fructose-1,6-diphosphatase), indicating the sensitivity of liver and kidney as target tissues in PER toxicity. Evidence is presented that both 2DG (500 mg kg-1 body wt. day-1 i.p.) and vitamin E (400 mg kg-1 body wt. day-1 by oral gavage) during concomitant administration prevented most of the above PER-induced biochemical and pathological alterations. These results suggest that early metabolic and pathological perturbations following exposure of PER in mice can provide the basis for its documented potential for chronic effects like cytotoxicity and may be involved in modulation of carcinogenicity.

Improving cancer radiotherapy with 2-deoxy-D-glucose: phase I/II clinical trials on human cerebral gliomas

PURPOSE

Evaluation of tolerance, toxicity, and feasibility of combining large fraction (5 Gy) radiotherapy with 2-deoxy-D-glucose (2DG), an inhibitor of glucose transport and glycolysis, which has been shown to differentially inhibit repair of radiation damage in cancer cells.

METHODS AND MATERIALS

Twenty patients with supratentorial glioma (Grade 3/4), following surgery were treated with four weekly fractions of oral 2DG (200 mg/kg body weight) followed by whole brain irradiation (5 Gy). Two weeks later, supplement focal radiation to the tumor (14 Gy/7 fractions) was given. Routine clinical evaluation, x-ray computerized tomography (CT), and magnetic resonance (MR) imaging were carried out to study the acute and late radiation effects.

RESULTS

All the 20 patients completed the treatment without any interruption. The vital parameters were within normal limits during the treatment. None reported headache during the treatment. Mild to moderate nausea and vomiting were observed during the days of combined therapy (2DG + RT) in 10 patients. No significant deterioration of the neurological status was observed during the treatment period. Seven patients were alive at 63, 43, 36, 28, 27, 19, and 18 months of follow-up. In these patients, the clinical and MR imaging studies did not reveal any late radiation effects.

CONCLUSIONS

Feasibility of administering the treatment (2DG + 5 Gy) is demonstrated by the excellent tolerance observed in all 20 patients. Further, the clinical and MR studies also show the absence of any brain parenchymal damage.

The role of glutamine and glucose analogues in metabolic inhibition of human myeloid leukaemia in vitro

1. Glutamine analogues L-[alpha S,5S]-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (acivicin) and 6-diazo-5-oxo-L-norleucine (DON) have been shown to possess cytotoxic activity against a wide variety of animal and human xenografted solid tumours, however their potential in man has been limited by toxicity. 2. We have analysed the effects of acivicin and DON on glutamine utilization to determine whether the reason for the disappointing therapeutic profile is solely due to the inefficient inhibition of glutamine metabolism. 3. Human myeloid leukaemic cells treated with acivicin inhibited ribonucleotide biosynthesis but not energy production via glutaminolysis and had little effect on viability, whereas treatment with DON inhibited both ribonucleotide biosynthesis and glutamine oxidation and resulted in reduced viability. 4. Treatment of the myeloid leukaemic cells with the glucose analogue 2-deoxy-D-glucose in addition to DON potentiated the inhibition of de novo nucleotide biosynthesis, glutaminolysis and glycolysis, and caused a further reduction in cell viability. 5. These results provide further support for the essential role of glutamine in cellular metabolism, and indicate that use of the glutamine analogue DON in the treatment of acute myeloid leukaemia may be more clinically effective if used in combination with 2-deoxy-D-glucose.

Potentiation of radiation effects in plateau phase human glioma cells by combination of metabolic inhibitors

Effects of glycolytic inhibitor 2-deoxy-D-glucose (2-DG) on radiation damage were studied in a human glioma cell line (BMG-1), grown to confluence in monolayer. After irradiation (60Co-gamma-rays, 2 Gy) and incubation with low concentrations of 2-DG (0.5, 1.25 mM; 2-DG/glucose = 0.1, 0.25; 2 hr), in the absence or presence of respiratory inhibitor KCN (0.5-2 mM), cells were trypsinized and plated to assay radiation induced cytogenetic damage (micronuclei formation). The observations made were: (1) 2-DG and/or KCN treatments did not induce damage in unirradiated cells. (2) Either of these treatments did not increase radiation induced micronuclei formation. (3) Presence of 2-DG along with KCN (1,2 mM) significantly enhanced the radiation induced micronuclei formation. (4) Preliminary experiments by macrocolony assay showed that radiation induced cell death was also significantly increased by the combined treatment. These observations suggest that presence of clinically feasible, low concentrations of 2-DG (2-DG/glucose < 0.5) for short intervals of time after radiation could increase radiation damage in non-cycling, hypoxic tumour cells with impaired oxidative and increased glycolytic energy metabolism.

Repair inhibition in tumours irradiated with fast protons and negative pions

Solid Ehrlich mouse tumours were irradiated in the 80 MeV proton beam of the Paul-Scherrer-Institute. The tumour volume was measured as a function of time after irradiation and two experimental endpoints were determined: local tumour control and minimal tumour volume after irradiation. The application of 2-deoxy-D-glucose (2-DG; 2 mg/kg) increased the radiation effect of protons by a factor of 1.4. The same tumour system was used with negative pions. Human tumours are usually irradiated with a mixed radiation produced by the "spot-scan-technique". This radiation quality was simulated in the mouse experiment by two successive irradiations with a spot of densely ionizing peak pions and a spot of sparsely ionizing plateau pions. Application of 2-DG raised the radiation effect due to the sparsely ionizing component again by a factor of 1.4. This indicates that clinical results in radiotherapy might be improved by application of 2-DG during the treatment.

Anticarcinoma activity of rhodamine 123 against a murine renal adenocarcinoma

The mitochondria of carcinoma cells retain the permeant cationic compound rhodamine 123 longer than the mitochondria of normal epithelial cells. The possibility of exploiting this difference in the chemotherapy of a murine renal adenocarcinoma was investigated. Rhodamine 123 exhibited anticarcinoma activity in mice and this activity was potentiated by 2-deoxyglucose and methylglyoxal bis(guanylhydrazone), a chemotherapeutic agent that is toxic to mitochondria. Prolonged retention of rhodamine 123 by renal tumor cells compared with normal renal epithelial cells was demonstrated by flow cytometry, perhaps explaining its antitumor activity. A combination of both mitochondrial toxins, rhodamine 123 and methylglyoxal bis(guanylhydrazone) produced the longest survival and had the greatest antitumor effect.

Inhibition of established rat fibrosarcoma growth by the glucose antagonist 2-deoxy-D-glucose

Sarcoma cells exhibit higher rates of glycolysis than normal tissues and may be dependent on glucose utilization for growth. Accordingly, we tested the ability of the glucose antimetabolite 2-deoxy-D-glucose (2-DG) to inhibit the growth of an established methylcholanthrene-induced rat fibrosarcoma in three groups of F344 rats with increasing subcutaneous inoculations of tumor (2 X 10(6) cells, 1 X 10(7) cells, and 1 mm tumor fragments). Rats were randomized to receive 2-DG or saline solution at doses of 0.75 gm/kg, 1.5 gm/kg, or 1.75 gm/kg, beginning 3 days after tumor implantation and continuing for 10 days. Tumors were removed and weighed on day 14. We measured tissue [14C]-2-DG levels in tumor, brain, liver, and muscle after intraperitoneal injection of radiolabeled 2-DG. In these same tissues we determined the activity of glucose-6-phosphatase (G-6-Pase), an enzyme which dephosphorylates the intracellular glycolytic inhibitor 2-DG-6-phosphate, thus reversing the antitumor effect of 2-DG. All groups treated with 2-DG had a significant reduction in tumor weight of 50% to 70% when compared with saline solution-treated controls. Toxicity was substantial at the highest dose of 2-DG, but minimal toxicity was noted at intermediate and low doses. Tumor had the greatest uptake of [14C]-2-DG, with low levels of G-6-Pase leading to prolonged retention and highest tissue levels of radiolabeled 2-DG. Use of 2-DG inhibits established sarcoma growth because it is rapidly transported into tumors, cannot be metabolized after phosphorylation, and is dephosphorylated and released slowly from tumor cells. Rat sarcoma growth is dependent on glucose utilization and can be effectively inhibited by glucose antagonism.

Efficacy of glycoprotein inhibitors alone and in combination with trifluridine in the treatment of murine herpetic keratitis

The present study examined the anti-herpetic effect of the glycoprotein inhibitors, hydroxynorvaline and 2-deoxyglucose, alone and in combination with trifluridine on murine ocular herpes. Following ocular inoculation with a large dose of HSV-1 RE strain (10(6) pfu), ICR mice were treated during the acute infection with different therapeutic regimens, and their efficacy was evaluated by ocular virus titers, clinical grading of blepharo-conjunctivitis and histological evaluation of stromal keratitis and iridocyclitis. The results following a large dose HSV-1 inoculum demonstrated that trifluridine was the best single therapeutic agent. Hydroxynorvaline and 2-deoxyglucose had no effect at all. Combination therapy of the glycoprotein inhibitors with trifluridine was no better than trifluridine alone. The mouse HSV-1 keratitis model proved to be an effective, economical alternative to the rabbit model for the evaluation of new antiviral agents.

Hyperthermia and radiation in vivo: effect of 2-deoxy-D-glucose

Since hypoxic cells rely heavily on glucose metabolism for energy, 2-deoxy-D-glucose (2-DG), an inhibitor of anaerobic glycolysis, would be expected to increase tumor cell killing by heat and thus enhance the effect of concurrent radiation. In order to test this hypothesis two types of BALB/c mouse tumors, one induced by subcutaneous injection of 10(6) herpes virus Type 2-transformed (H238) cells and the other by injection of 1.6 X 10(5) 1,2-dimethylhydrazine-transformed (#51) cells in the right thigh, were subjected to radiation, 2-DG, and heat used singly and in various combinations. Control mice were injected with saline. Three to four weeks after inoculation the mice were assigned to one of eight treatment groups (28 mice/group) so that average tumor volume/group before treatment would be equivalent. A single 2000 rad dose of radiation 3 hr prior to heat and 2-DG injected intraperitoneally at 1 g/kg 30 min before heating were given to some of the groups. Localized heat at 43.5 +/- 0.1 degrees C for 30 min, when used, was administered by means of a water bath. Rectal temperatures were kept below 39 degrees C, whereas intratumor temperatures reached a maximum of 42 degrees C. After treatment, tumor volume, mouse weight, and mortality were noted twice a week for four weeks. In both tumor models, mice receiving radiation plus heat, and radiation plus heat plus 2-DG, had significantly smaller tumors over the entire 4 to 28 day range after treatment than saline-injected control mice. In addition, in the H238 tumor model, addition of 2-DG to treatment with radiation and heat resulted in significantly smaller tumors at 25 days. 2-DG alone or in combination with heat (without radiation) resulted in significantly smaller H238 cell-induced tumors at day 28 post-treatment when compared to the saline controls. The H238 tumor-bearing mice experienced a significant (4.7%) loss in total body weight after heating. It could be that heating trauma produced dehydration and possibly also decreased caloric intake to an extent which could be measured in weight loss. This observation, however, was not made in the heated mice in the #51 tumor model.

Mouse neoplasia and immunity: effects of radiation, hyperthermia, 2-deoxy-D-glucose, and Corynebacterium parvum

Radiation (XRT), hyperthermia, 2-deoxy-D-glucose (2DG), and Corynebacterium parvum were given in various combinations to BALB/c mice injected with herpes virus type 2-transformed (H238) cells. Addition of heat significantly increased the antitumor effects of XRT, and the combination of XRT + 2DG + heat resulted in the highest incidence of complete tumor regression. Enhanced activity of phytohemagglutinin-responsive T lymphocytes and natural killer cells capable of killing YAC-1 tumor cells was noted in some of the treatment groups while tumor volume was similar for all of the groups. This enhancement was most likely to be achieved when heat was included as part of the treatment protocol.