Enzymatic features of the glucose metabolism in tumor cells

Chemical Memory with Discrete Turing Patterns Appearing in the Glycolytic Reaction

Memory is an essential element in information processing devices. We investigated a network formed by just three interacting nodes representing continuously stirred tank reactors (CSTRs) in which the glycolytic reaction proceeds as a potential realization of a chemical memory unit. Our study is based on the 2-variable computational model of the reaction. The model parameters were selected such that the system has a stable limit cycle and several distinct, discrete Turing patterns characterized by stationary concentrations at the nodes. In our interpretation, oscillations represent a blank memory unit, and Turing patterns code information. The considered memory can preserve information on one of six different symbols. The time evolution of the nodes was individually controlled by the inflow of ATP. We demonstrate that information can be written with a simple and short perturbation of the inflow. The perturbation applies to only one or two nodes, and it is symbol specific. The memory can be erased with identical inflow perturbation applied to all nodes. The presented idea of pattern-coded memory applies to other reaction networks that allow for discrete Turing patterns. Moreover, it hints at the experimental realization of memory in a simple system with the glycolytic reaction.

Glucose Metabolism in Burns-What Happens?

Severe burns represent an important challenge for patients and medical teams. They lead to profound metabolic alterations, trigger a systemic inflammatory response, crush the immune defense, impair the function of the heart, lungs, kidneys, liver, etc. The metabolism is shifted towards a hypermetabolic state, and this situation might persist for years after the burn, having deleterious consequences for the patient's health. Severely burned patients lack energy substrates and react in order to produce and maintain augmented levels of glucose, which is the fuel "ready to use" by cells. In this paper, we discuss biological substances that induce a hyperglycemic response, concur to insulin resistance, and determine cell disturbance after a severe burn. We also focus on the most effective agents that provide pharmacological modulations of the changes in glucose metabolism.

Melatonin improves cognitive behavior, oxidative stress, and metabolism in tumor-prone lethal giant larvae mutant of Drosophila melanogaster

Mutant lethal giant larvae (lgl) flies (Drosophila melanogaster) are known to develop epithelial tumors with invasive characteristics. The present study has been conducted to investigate the influence of melatonin (0.025 mM) on behavioral responses of lgl mutant flies as well as on biochemical indices (redox homeostasis, carbohydrate and lipid metabolism, transaminases, and minerals) in hemolymph, and head and intestinal tissues. Behavioral abnormalities were quantitatively observed in lgl flies but were found normalized among melatonin-treated lgl flies. Significantly decreased levels of lipid peroxidation products and antioxidants involved in redox homeostasis were observed in hemolymph and tissues of lgl flies, but had restored close to normalcy in melatonin-treated flies. Carbohydrates including glucose, trehalose, and glycogen were decreased and increased in the hemolymph and tissues of lgl and melatonin-treated lgl flies, respectively. Key enzymes of carbohydrate metabolism showed a significant increment in their levels in lgl mutants but had restored close to wild-type baseline levels in melatonin-treated flies. Variables of lipid metabolism showed significantly inverse levels in hemolymph and tissues of lgl flies, while normalization of most of these variables was observed in melatonin-treated mutants. Lipase, chitinase, transaminases, and alkaline phosphatase showed an increment in their activities and minerals exhibited decrement in lgl flies; reversal of changes was observed under melatonin treatment. The impairment of cognition, disturbance of redox homeostasis and metabolic reprogramming in lgl flies, and restoration of normalcy in all these cellular and behavioral processes indicate that melatonin could act as oncostatic and cytoprotective agents in Drosophila.

Investigation of glucose catabolism in hypoxic Mcf 7 breast cancer culture

Hypoxia plays an important role in tumor phenotype and progression and alters glycolysis, with changes in signaling pathways that develop in response to hypoxia. In this study, the effects of oxygen (normoxia/hypoxia) and of glucose levels on the glucose metabolism was investigated in MCF-7 cancer cells. Under either normoxia or hypoxia conditions, the cells were exposed to glucose at different concentrations (0, 5.5, 15 or 55 mM) for either 3, 6, 12, 24 or 48 h. In all groups, cell viability, levels of key enzymes reflecting glycolytic metabolism in cell lysates, glucose consumed in the medium and extracellular lactate levels and wound closure percentages were determined. In hypoxic cells, intracellular consumption of glucose, and extracellular lactate levels due to increased glucose concentration were observed to be higher (compared to normoxia) and as a result of prolonged exposure to hypoxia, cells were observed to develop resistance to the prolonged exposure to hypoxia. The number of glycolytic enzymes obtained at different levels proved that cells had different potential capacities and changing mechanisms for the metabolic needs of the cell depending on the glucose amount in the medium and time in adapting to the oxygen tension. This study showed that there was an important interaction between hypoxia and glucose metabolism in general, and it was concluded that metabolic processes activated by hypoxia could offer new therapeutic targets.

A New Mathematical Model for Controlling Tumor Growth Based on Microenvironment Acidity and Oxygen Concentration

Hypoxia and the pH level of the tumor microenvironment have a great impact on the treatment of tumors. Here, the tumor growth is controlled by regulating the oxygen concentration and the acidity of the tumor microenvironment by introducing a two-dimensional multiscale cellular automata model of avascular tumor growth. The spatiotemporal evolution of tumor growth and metabolic variations is modeled based on biological assumptions, physical structure, states of cells, and transition rules. Each cell is allocated to one of the following states: proliferating cancer, nonproliferating cancer, necrotic, and normal cells. According to the response of the microenvironmental conditions, each cell consumes/produces metabolic factors and updates its state based on some stochastic rules. The input parameters are compatible with cancer biology using experimental data. The effect of neighborhoods during mitosis and simulating spatial heterogeneity is studied by considering multicellular layer structure of tumor. A simple Darwinist mutation is considered by introducing a critical parameter (Nmm) that affects division probability of the proliferative tumor cells based on the microenvironmental conditions and cancer hallmarks. The results show that Nmm regulation has a significant influence on the dynamics of tumor growth, the growth fraction, necrotic fraction, and the concentration levels of the metabolic factors. The model not only is able to simulate the in vivo tumor growth quantitatively and qualitatively but also can simulate the concentration of metabolic factors, oxygen, and acidity graphically. The results show the spatial heterogeneity effects on the proliferation of cancer cells and the rest of the system. By increasing Nmm, tumor shrinkage and significant increasing in the oxygen concentration and the pH value of the tumor microenvironment are observed. The results demonstrate the model's ability, providing an essential tool for simulating different tumor evolution scenarios of a patient and reliable prediction of spatiotemporal progression of tumors for utilizing in personalized therapy.

Molecular biological investigation of temozolomide and KC7F2 combination in U87MG glioma cell line

Glioblastom Multiforme (GBM) is the most invasive and malignant member of the IV grade of the subclass Astrocytoma according to the last assessment of the 2016 WHO report. Due to the resistance to treatment and weak response, as well as the topographical structure of the blood brain barrier, the treatment is also difficult due to the severe clinical manifestation, and new treatment methods and new therapeutic agents are needed. Temozolomide (TMZ) is widely used in the treatment of glioblastoma and is considered as the primary treatment modality. TMZ, a member of the class of cognitive agents, is currently considered the most effective drug because it can easily pass through the blood brain barrier. Glucose metabolism is a complex energy producing machine that, a glucose molecule produces 38 molecules of ATP after full glycolytic catabolism. According to Otto Warburg's numerous studies cancer cells perform the first glycolytic step without entering the mitochondrial step. These cells produce lactic acid and make the micro-media more acidic even in aerobic conditions. This phenomenon is attributed to the Warburg hypothesis and either as aerobic glycolysis. Although glycolysis enzymes are the primary actors of this phenotypic expression, some genetic and epigenetic factors are no exception. We experimentally used KC7F2 active ingredient to target cancer metabolism. In our study, we evaluated cancer metabolism in combination with the effect of TMZ chemotherapeutic agent, examining the effect of two different agents separately and in combination to observe the effects of cancer cell proliferation, survival, apoptosis and expression of metabolism genes on expression. We observed that the combined effect of reduced the effective dose of the TMZ alkylating agent and that the effect was increased and the effect of the combined teraphy is assessed from a metabolic point of view and that it suppresses aerobic glycolysis.

Glycolytic competence in gastric adenocarcinomas negatively impacts survival outcomes of patients treated with salvage paclitaxel-ramucirumab

INTRODUCTION

For energy production, cancer cells maintain a high rate of glycolysis instead of oxidative phosphorylation converting glucose into lactic acid. This metabolic shift is useful to survive in unfavorable microenvironments. We investigated whether a positive glycolytic profile (PGP) in gastric adenocarcinomas may be associated with unfavorable outcomes under an anticancer systemic therapy, including the anti-angiogenic ramucirumab.

MATERIALS AND METHODS

Normal mucosa (NM) and primary tumor (PT) of 40 metastatic gastric adenocarcinomas patients who received second-line paclitaxel-ramucirumab (PR) were analyzed for mRNA expression of the following genes: HK-1, HK-2, PKM-2, LDH-A, and GLUT-1. Patients were categorized with PGP when at least a doubling of mRNA expression (PT vs. NM) in all glycolytic core enzymes (HK-1 or HK-2, PKM-2, LDH-A) was observed. PGP was also related to TP53 mutational status.

RESULTS

Mean LDH-A, HK-2, PKM-2 mRNA expression levels were significantly higher in PT compared with NM. 18 patients were classified as PGP, which was associated with significantly worse progression-free and overall survival times. No significant association was observed between PGP and clinical-pathologic features, including TP53 positive mutational status, in 28 samples.

CONCLUSIONS

Glycolytic proficiency may negatively affect survival outcomes of metastatic gastric cancer patients treated with PR systemic therapy. TP53 mutational status alone does not seem to explain such a metabolic shift.

Metabolic heterogeneity of human hepatocellular carcinoma: implications for personalized pharmacological treatment

Metabolic reprogramming is a characteristic feature of cancer cells, but there is no unique metabolic program for all tumors. Genetic and gene expression studies have revealed heterogeneous inter- and intratumor patterns of metabolic enzymes and membrane transporters. The functional implications of this heterogeneity remain often elusive. Here, we applied a systems biology approach to gain a comprehensive and quantitative picture of metabolic changes in individual hepatocellular carcinoma (HCC). We used protein intensity profiles determined by mass spectrometry in samples of 10 human HCCs and the adjacent noncancerous tissue to calibrate Hepatokin1, a complex mathematical model of liver metabolism. We computed the 24-h profile of 18 metabolic functions related to carbohydrate, lipid, and nitrogen metabolism. There was a general tendency among the tumors toward downregulated glucose uptake and glucose release albeit with large intertumor variability. This finding calls into question that the Warburg effect dictates the metabolic phenotype of HCC. All tumors comprised elevated β-oxidation rates. Urea synthesis was found to be consistently downregulated but without compromising the tumor's capacity for ammonia detoxification owing to increased glutamine synthesis. The largest intertumor heterogeneity was found for the uptake and release of lactate and the size of the cellular glycogen content. In line with the observed metabolic heterogeneity, the individual HCCs differed largely in their vulnerability against pharmacological treatment with metformin. Taken together, our approach provided a comprehensive and quantitative characterization of HCC metabolism that may pave the way for a computational a priori assessment of pharmacological therapies targeting metabolic processes of HCC.

Modulating the function of ABCB1: in vitro and in vivo characterization of sitravatinib, a tyrosine kinase inhibitor

BACKGROUND

Overexpression of ATP-binding cassette (ABC) transporter is a major contributor to multidrug resistance (MDR), in which cancer cells acquire resistance to a wide spectrum of chemotherapeutic drugs. In this work, we evaluated the sensitizing effect of sitravatinib, a broad-spectrum tyrosine kinase inhibitor (TKI), on ATP-binding cassette subfamily B member 1 (ABCB1)- and ATP-binding cassette subfamily C member 10 (ABCC10)-mediated MDR.

METHODS

MTT assay was conducted to examine cytotoxicity and evaluate the sensitizing effect of sitravatinib at non-toxic concentrations. Tritium-labeled paclitaxel transportation, Western blotting, immunofluorescence analysis, and ATPase assay were carried out to elucidate the mechanism of sitravatinib-induced chemosensitization. The in vitro findings were translated into preclinical evaluation with the establishment of xenograft models.

RESULTS

Sitravatinib considerably reversed MDR mediated by ABCB1 and partially antagonized ABCC10-mediated MDR. Our in silico docking simulation analysis indicated that sitravatinib strongly and stably bound to the transmembrane domain of ABCB1 human-mouse chimeric model. Furthermore, sitravatinib inhibited hydrolysis of ATP and synchronously decreased the efflux function of ABCB1. Thus, sitravatinib could considerably enhance the intracellular concentration of anticancer drugs. Interestingly, no significant alterations of both expression level and localization of ABCB1 were observed. More importantly, sitravatinib could remarkably restore the antitumor activity of vincristine in ABCB1-mediated xenograft model without observable toxic effect.

CONCLUSIONS

The findings in this study suggest that the combination of sitrvatinib and substrate antineoplastic drugs of ABCB1 could attenuate the MDR mediated by the overexpression of ABCB1.

2-Deoxy-d-Glucose and Its Analogs: From Diagnostic to Therapeutic Agents

The ability of 2-deoxy-d-glucose (2-DG) to interfere with d-glucose metabolism demonstrates that nutrient and energy deprivation is an efficient tool to suppress cancer cell growth and survival. Acting as a d-glucose mimic, 2-DG inhibits glycolysis due to formation and intracellular accumulation of 2-deoxy-d-glucose-6-phosphate (2-DG6P), inhibiting the function of hexokinase and glucose-6-phosphate isomerase, and inducing cell death. In addition to glycolysis inhibition, other molecular processes are also affected by 2-DG. Attempts to improve 2-DG’s drug-like properties, its role as a potential adjuvant for other chemotherapeutics, and novel 2-DG analogs as promising new anticancer agents are discussed in this review.

Genotoxicity and glucose tolerance induction by acetyltriethylcitrate, substitute plasticizer compared to di(2-ethylhexyl)phthalate

As di(2-ethylhexyl) phthalate (DEHP), one of phthalates, is classified as probable human carcinogens in EPA, acetyltriethyl citrate(ATEC), one of aliphatic esters, could be applied to DEHP substitute. ATEC is used as plasticizers in cosmetics and nail products. Here, we studied whether ATEC might have genotoxic potential and induce glucose tolerance as compared to DEHP. Genotoxicity was determined by Ames test with histidine-requiring Salmonella typhimurium (TA98, TA100, TA1535 and TA1537) and tryptophan-requiring Escherichia coli (WP2uvrA(pKM101)) strains, chromosomal aberration assay with Chinese hamster lung(CHL/IU) cells, and micronucleus test with bone marrow cells of CD-1 mice. The number of revertants was not significantly changed in Ames test. The frequency of cells with chromosome aberrations was less than 5% in ATEC- or DEHP-treated cells for 6 or 24 h. In addition, no statistically significant increase was observed for the incidence of micronucleated polychromatic erythrocytes (MNPCE) in polychromatic erythrocytes (PCE) and for the ratio of PCE among total erythrocytes at 24 or 48 h after the treatment of mice with ATEC or DEHP. In the meanwhile, blood glucose level (BGL) was increased by the treatment of mice with DEHP or ATEC for 5 consecutive days. Additional 7 days later, BGL by DEHP was recovered to normal level, but not that by ATEC. Then, taken together, our results suggest that ATEC could disrupt glucose metabolism under our experimental conditions. Therefore, although DEHP and ATEC may not be genotoxic, our data should be helpful for persons with the problem in glucose metabolism to choose products containing DEHP or ATEC.

Cellular Gene Expression during Hepatitis C Virus Replication as Revealed by Ribosome Profiling

Background: Hepatitis C virus (HCV) infects human liver hepatocytes, often leading to liver cirrhosis and hepatocellular carcinoma (HCC). It is believed that chronic infection alters host gene expression and favors HCC development. In particular, HCV replication in Endoplasmic Reticulum (ER) derived membranes induces chronic ER stress. How HCV replication affects host mRNA translation and transcription at a genome wide level is not yet known. Methods: We used Riboseq (Ribosome Profiling) to analyze transcriptome and translatome changes in the Huh-7.5 hepatocarcinoma cell line replicating HCV for 6 days. Results: Established viral replication does not cause global changes in host gene expression—only around 30 genes are significantly differentially expressed. Upregulated genes are related to ER stress and HCV replication, and several regulated genes are known to be involved in HCC development. Some mRNAs (PPP1R15A/GADD34, DDIT3/CHOP, and TRIB3) may be subject to upstream open reading frame (uORF) mediated translation control. Transcriptional downregulation mainly affects mitochondrial respiratory chain complex core subunit genes. Conclusion: After establishing HCV replication, the lack of global changes in cellular gene expression indicates an adaptation to chronic infection, while the downregulation of mitochondrial respiratory chain genes indicates how a virus may further contribute to cancer cell-like metabolic reprogramming (“Warburg effect”) even in the hepatocellular carcinoma cells used here.

Immuno-oncology agent IPI-549 is a modulator of P-glycoprotein (P-gp, MDR1, ABCB1)-mediated multidrug resistance (MDR) in cancer: In vitro and in vivo

Phosphoinositide 3-kinase gamma isoform (PI3Kγ) plays a critical role in myeloid-derived cells of the immunosuppressive tumor microenvironment. IPI-549, a recently discovered small molecule selective PI3Kγ inhibitor, is currently under immuno-oncology clinical trials in combination with nivolumab, an anti-PD-1 monoclonal antibody immune checkpoint blocker. The purpose of this study is to investigate whether IPI-549 could reverse P-glycoprotein (P-gp)-mediated MDR when combined with chemotherapeutic substrates of P-gp. Cytotoxicity assays showed that IPI-549 reverses P-gp-mediated MDR in SW620/Ad300 and LLC-PK-MDR1 cells. IPI-549 increases the amount of intracellular paclitaxel and inhibits the efflux of paclitaxel out of SW620/Ad300 cells. ABCB1-ATPase assay showed that IPI-549 stimulates the activity of ABCB1-ATPase. IPI-549 does not alter the expression and does not affect the subcellular localization of P-gp in SW620/Ad300 cells. The combination of IPI-549 with paclitaxel showed that IPI-549 potentiates the anti-tumor effects of paclitaxel in P-gp-overexpressing MDR SW620/Ad300 xenograft tumors. With clinical trials beginning to add newly approved immune checkpoint-based immunotherapy into standard-of-care immunogenic chemotherapy to improve patient outcomes, our findings support the rationale of adding IPI-549 to both the chemotherapeutic and immunotherapeutic aspects of cancer combination treatment strategies.

Regorafenib antagonizes BCRP-mediated multidrug resistance in colon cancer

Overexpression of breast cancer resistance protein (BCRP) has been shown to produce multidrug resistance (MDR) in colon cancer, leading to major obstacles for chemotherapy. In this study, we evaluated the effect of regorafenib, an oral multi-kinase inhibitor, in inhibiting BCRP-mediated MDR in silico, in vitro and in vivo. We found that regorafenib significantly sensitized MDR colon cancer cells to BCRP substrates by increasing their intracellular accumulation. There are no significant changes in the expression level or the subcellular distribution of BCRP in the cells exposed to regorafenib. Investigation of the mechanism revealed that regorafenib stimulated BCRP ATPase activity. Our induced-fit docking and molecular dynamics simulations suggested the existence of a strong and stable interaction between regorafenib and the transmembrane domain of human crystalized BCRP. In vivo tumor xenograft study revealed that the combination of regorafenib and topotecan exhibited synergistic effects on mitoxantrone-resistant S1-M1-80 xenograft tumors. In conclusion, our studies indicate that regorafenib would be beneficial in combating MDR in colon cancer.

Targeting Strategies for Glucose Metabolic Pathways and T Cells in Colorectal Cancer

Colorectal cancer is a heterogeneous group of diseases that result from the accumulation of different sets of genomic alterations, together with epigenomic alterations, and it is influenced by tumor-host interactions, leading to tumor cell growth and glycolytic imbalances. This review summarizes recent findings that involve multiple signaling molecules and downstream genes in the dysregulated glycolytic pathway. This paper further discusses the role of the dysregulated glycolytic pathway in the tumor initiation, progression and the concomitant systemic immunosuppression commonly observed in colorectal cancer patients. Moreover, the relationship between colorectal cancer cells and T cells, especially CD8+ T cells, is discussed, while different aspects of metabolic pathway regulation in cancer cell proliferation are comprehensively defined. Furthermore, this study elaborates on metabolism in colorectal cancer, specifically key metabolic modulators together with regulators, glycolytic enzymes, and glucose deprivation induced by tumor cells and how they inhibit T-cell glycolysis and immunogenic functions. Moreover, metabolic pathways that are integral to T cell function, differentiation, and activation are described. Selective metabolic inhibitors or immunemodulation agents targeting these pathways may be clinically useful to increase effector T cell responses for colorectal cancer treatment. However, there is a need to identify specific antigens using a cancer patient-personalized approach and combination strategies with other therapeutic agents to effectively target tumor metabolic pathways.

Amino Acid Signature in Human Melanoma Cell Lines from Different Disease Stages

Cancer cells rewire metabolism to sustain high proliferation rates. Beside glycolysis and glutaminolysis, amino acids substitute as energy source, feed fatty acid biosynthesis and represent part of the secretome of transformed cells, including melanoma. We have therefore investigated acetate, pyruvate and the amino acid composition of the secretome of human melanoma cells representing the early slow (WM35, WM278, WM793b and VM21) and metastatic fast (A375, 518a2, 6F and WM8) growth phase in order to identify possible signalling components within these profiles. Proliferation assays and a principle component analysis revealed a stringent difference between the fast and slow growing melanoma cells. Moreover, upon inhibition of the mevalonate pathway, glutamic acid and alanine were identified as the central difference in the conditional media. A supplementation of the media with glutamic acid and the combination with alanine significantly accelerated the proliferation, migration and invasion of early stage melanoma cells, but not metastatic cells. Finally, the inhibition of the mevalonate pathway abolished the growth advantage of the melanoma cells in a time dependent manner. Taken together, these data corroborate a stage specific response in growth and aggressiveness to extracellular glutamic acid and alanine, indicative for microenvironmental signalling of individual amino acids.

Metabolic Profile of Oral Squamous Carcinoma Cell Lines Relies on a Higher Demand of Lipid Metabolism in Metastatic Cells

Tumor cells are subjected to a broad range of selective pressures. As a result of the imposed stress, subpopulations of surviving cells exhibit individual biochemical phenotypes that reflect metabolic reprograming. The present work aimed at investigating metabolic parameters of cells displaying increasing degrees of metastatic potential. The metabolites present in cell extracts fraction of tongue fibroblasts and of cell lines derived from human tongue squamous cell carcinoma lineages displaying increasing metastatic potential (SCC9 ZsG, LN1 and LN2) were analyzed by ¹H NMR (nuclear magnetic resonance) spectroscopy. Living, intact cells were also examined by the non-invasive method of fluorescence lifetime imaging microscopy (FLIM) based on the auto fluorescence of endogenous NADH. The cell lines reproducibly exhibited distinct metabolic profiles confirmed by Partial Least-Square Discriminant Analysis (PLS-DA) of the spectra. Measurement of endogenous free and bound NAD(P)H relative concentrations in the intact cell lines showed that ZsG and LN1 cells displayed high heterogeneity in the energy metabolism, indicating that the cells would oscillate between glycolysis and oxidative metabolism depending on the microenvironment’s composition. However, LN2 cells appeared to have more contributions to the oxidative status, displaying a lower NAD(P)H free/bound ratio. Functional experiments of energy metabolism, mitochondrial physiology, and proliferation assays revealed that all lineages exhibited similar energy features, although resorting to different bioenergetics strategies to face metabolic demands. These differentiated functions may also promote metastasis. We propose that lipid metabolism is related to the increased invasiveness as a result of the accumulation of malonate, methyl malonic acid, n-acetyl and unsaturated fatty acids (CH₂)_n in parallel with the metastatic potential progression, thus suggesting that the NAD(P)H reflected the lipid catabolic/anabolic pathways.

A Metabolic Therapy for Malignant Glioma Requires a Clinical Measure

Cancers are "reprogrammed" to use a much higher rate of glycolysis (GLY) relative to oxidative phosphorylation (OXPHOS), even in the presence of adequate amounts of oxygenation. Originally identified by Nobel Laureate Otto Warburg, this hallmark of cancer has recently been termed metabolic reprogramming and represents a way for the cancer tissue to divert carbon skeletons to produce biomass. Understanding the mechanisms that underlie this metabolic shift should lead to better strategies for cancer treatments. Malignant gliomas, cancers that are very resistant to conventional treatments, are highly glycolytic and seem particularly suited to approaches that can subvert this phenotype.

Fructose-1,6-bisphosphate couples glycolytic flux to activation of Ras

Yeast and cancer cells share the unusual characteristic of favoring fermentation of sugar over respiration. We now reveal an evolutionary conserved mechanism linking fermentation to activation of Ras, a major regulator of cell proliferation in yeast and mammalian cells, and prime proto-oncogene product. A yeast mutant (tps1∆) with overactive influx of glucose into glycolysis and hyperaccumulation of Fru1,6bisP, shows hyperactivation of Ras, which causes its glucose growth defect by triggering apoptosis. Fru1,6bisP is a potent activator of Ras in permeabilized yeast cells, likely acting through Cdc25. As in yeast, glucose triggers activation of Ras and its downstream targets MEK and ERK in mammalian cells. Biolayer interferometry measurements show that physiological concentrations of Fru1,6bisP stimulate dissociation of the pure Sos1/H-Ras complex. Thermal shift assay confirms direct binding to Sos1, the mammalian ortholog of Cdc25. Our results suggest that the Warburg effect creates a vicious cycle through Fru1,6bisP activation of Ras, by which enhanced fermentation stimulates oncogenic potency.

Yeast and cancer cells both favor sugar fermentation in aerobic conditions. Here the authors describe a conserved mechanism from yeast to mammals where the glycolysis intermediate fructose-1,6-bisphosphate binds Cdc25/Sos1 and couples increased glycolytic flux to increased Ras proto-oncoprotein activity.

Lactate-An Integrative Mirror of Cancer Metabolism

The technique of induced metabolic bioluminescence imaging (imBI) has been developed to obtain a "snapshot" of the momentary metabolic status of biological tissues. Using cryosections of snap-frozen tissue specimens, imBI combines highly specific and sensitive in situ detection of metabolites with a spatial resolution on a microscopic level and with metabolic imaging in relation to tissue histology. Here, we present the application of imBI in human colorectal cancer. Comparing the metabolic information of one biopsy with that of 2 or 3 biopsies per individual cancer, the classification into high versus low lactate tumors, reflecting different glycolytic activities, based on a single biopsy was in agreement with the result from multiple biopsies in 83 % of all cases. We further demonstrate that the metabolic status of tumor tissue can be preserved at least over 10 years by storage in liquid nitrogen, but not by storage at -80 °C. This means that tissue banking with long-term preservation of the metabolic status is possible at -180 °C, which may be relevant for studies on long-term survival of cancer patients. As with other tumor entities, tissue lactate concentration was shown to be correlated with tumor development and progression in colorectal cancer. At first-time diagnosis, lactate values were low in rectal normal tissue and adenomas, were significantly elevated to intermediate levels in non-metastatic adenocarcinomas, and were very high in carcinomas with distant metastasis. There was an inverse behavior of tissue glucose concentration under corresponding conditions. The expression level of monocarboxylate transporter-4 (MCT4) was positively correlated with the tumor lactate concentration and may thus contribute to high lactate tumors being associated with a high degree of malignancy.

Selective reversal of BCRP-mediated MDR by VEGFR-2 inhibitor ZM323881

The expression of breast cancer resistant protein (BCRP) in lung cancer is correlated with development of multidrug resistance (MDR) and therefore leads to lower response to chemotherapy. ZM323881, a previously developed selective VEGFR-2 inhibitor, was found to have inhibitory effects on BCRP-mediated MDR in this investigation. ZM323881 significantly decreased the cytotoxic doses of mitoxantrone and SN-38 in BCRP-overexpressing NCI-H460/MX20 cells. Mechanistic studies revealed that ZM323881 effected by inhibiting BCRP-mediated drug efflux, leading to intracellular accumulation of BCRP substrates. No significant alteration in the expression levels and localization pattern of BCRP was observed when BCRP-overexpressing cells were exposed to ZM323881. Stimulated bell-shaped ATPase activities were observed. Molecular docking suggested that ZM323881 binds to the modulator site of BCRP and the binding pose is stable validated by 100ns molecular dynamic simulation. Overall, our results indicated that ZM323881 reversed BCRP-related MDR by inhibiting its efflux function. These findings might be useful in developing combination chemotherapy for MDR cancer treatment.

Combinatorial high-throughput experimental and bioinformatic approach identifies molecular pathways linked with the sensitivity to anticancer target drugs

Effective choice of anticancer drugs is important problem of modern medicine. We developed a method termed OncoFinder for the analysis of new type of biomarkers reflecting activation of intracellular signaling and metabolic molecular pathways. These biomarkers may be linked with the sensitivity to anticancer drugs. In this study, we compared the experimental data obtained in our laboratory and in the Genomics of Drug Sensitivity in Cancer (GDS) project for testing response to anticancer drugs and transcriptomes of various human cell lines. The microarray-based profiling of transcriptomes was performed for the cell lines before the addition of drugs to the medium, and experimental growth inhibition curves were built for each drug, featuring characteristic IC₅₀ values. We assayed here four target drugs - Pazopanib, Sorafenib, Sunitinib and Temsirolimus, and 238 different cell lines, of which 11 were profiled in our laboratory and 227 - in GDS project. Using the OncoFinder-processed transcriptomic data on ∼600 molecular pathways, we identified pathways showing significant correlation between pathway activation strength (PAS) and IC₅₀ values for these drugs. Correlations reflect relationships between response to drug and pathway activation features. We intersected the results and found molecular pathways significantly correlated in both our assay and GDS project. For most of these pathways, we generated molecular models of their interaction with known molecular target(s) of the respective drugs. For the first time, our study uncovered mechanisms underlying cancer cell response to drugs at the high-throughput molecular interactomic level.

Modulatory Role of Shorea robusta Bark on Glucose-metabolizing Enzymes in Diethylnitrosamine Induced Hepatocellular Carcinoma in Rats

Introduction:

The modulations of glucose-metabolizing enzyme activities play a vital rolein the depletion of energy metabolism and leads to inhibition of cancer growth.

Objective:

To find the effect of shorearobusta bark extract on glucose-metbolizing enzymes in diethylnitrosamine (DEN) induced hepatocellular carcinoma rats.

Materials and Methods:

Biochemical evaluation of glucose metabolizing enzyme were done in before and after shorearobusta bark extract (500mg/kg) treatment in DEN induced rats.

Results:

A significant increasein the activities of the key glycolytic enzymes viz., hexokinase and phosphoglucoisomerase, with a significant decrease in the gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-bisphosphatasewere observed in HCC bearing rats, when compared with the control. Administration of shorearobusta extract caused a significant decrease in theactivities of glycolytic enzymes and an increase in the gluconeogenic enzymes activities to near normal values.

Conclusion:

The current findings suggest that the S. robusta extract has a definite modulating role on the key enzymes ofglucose-metabolism in HCC. The modulatory effect may be due to the phytoactive constituents present in the extract of S. robusta.

SUMMARY

Administration of shorea robusta bark extract caused a significant decrease in the activities of glycolytic enzymes and an increase in the gluconeogenic enzymes activities to near normal values. The S. robusta extract has modulatory activity on the carbohydrate metabolism in DEN-induced HCC bearing rats through a mechanism that which does not provoke any acute biochemical disturbances in the metabolic pathways of glycolysis and gluconeogenesis. The modulatory effect of S. robusta extract may be attributed to the presence of active compounds such as polyphenols and flavonoids.

Abbreviations used: HCC: Hepatocellular Carcinoma, SRBE: Shorearobusta bark extract; HEX: Hexokinase; PGI: Phosphoglucoisomerase; DEN: Diethylnitrosamine.

Facilitative glucose transporters: Implications for cancer detection, prognosis and treatment

It is long recognized that cancer cells display increased glucose uptake and metabolism. In a rate-limiting step for glucose metabolism, the glucose transporter (GLUT) proteins facilitate glucose uptake across the plasma membrane. Fourteen members of the GLUT protein family have been identified in humans. This review describes the major characteristics of each member of the GLUT family and highlights evidence of abnormal expression in tumors and cancer cells. The regulation of GLUTs by key proliferation and pro-survival pathways including the phosphatidylinositol 3-kinase (PI3K)-Akt, hypoxia-inducible factor-1 (HIF-1), Ras, c-Myc and p53 pathways is discussed. The clinical utility of GLUT expression in cancer has been recognized and evidence regarding the use of GLUTs as prognostic or predictive biomarkers is presented. GLUTs represent attractive targets for cancer therapy and this review summarizes recent studies in which GLUT1, GLUT3, GLUT5 and others are inhibited to decrease cancer growth.

Infection with Mycobacterium tuberculosis induces the Warburg effect in mouse lungs

To elucidate the little-known bioenergetic pathways of host immune cells in tuberculosis, a granulomatous disease caused by the intracellular pathogen Mycobacterium tuberculosis, we characterized infected murine lung tissue by transcriptomic profiling and confocal imaging. Transcriptomic analysis revealed changes of host energy metabolism during the course of infection that are characterized by upregulation of key glycolytic enzymes and transporters for glucose uptake, and downregulation of enzymes participating in the tricarboxylic acid cycle and oxidative phosphorylation. Consistent with elevated glycolysis, we also observed upregulation of a transporter for lactate secretion and a V type H(+) -ATPase involved in cytosolic pH homeostasis. Transcription profiling results were corroborated by immunofluorescence microscopy showing increased expression of key glycolytic enzymes in macrophages and T cells in granulomatous lesions. Moreover, we found increased mRNA and protein levels in macrophages and T cells of hypoxia inducible factor 1 alpha (HIF-1α), the regulatory subunit of HIF-1, a master transcriptional regulator. Thus, our findings suggest that immune cells predominantly utilize aerobic glycolysis in response to M. tuberculosis infection. This bioenergetic shift is similar to the Warburg effect, the metabolic signature of cancer cells. Finding immunometabolic changes during M. tuberculosis infection opens the way to new strategies for immunotherapy against tuberculosis.

Manipulation of tumor metabolism for therapeutic approaches: ovarian cancer-derived cell lines as a model system

BACKGROUND

Malignant transformation of cells is often accompanied by up-regulation of glycolysis-related enzymes and transporters, as well as a distortion of mitochondrial respiration. As a consequence, most malignant tumors utilize high amounts of glucose and produce and accumulate high concentrations of lactate, even in the presence of oxygen. This phenomenon has been termed 'Warburg Effect'. Here, we aimed at resolving the interrelation between tumor metabolism, reactive oxygen species, double strand DNA breaks and radio-resistance in ovarian cancer-derived cells.

METHODS

As a model system two ovarian cancer-derived cell lines, OC316 and IGROV-1, and its corresponding xenografts were used. First, the metabolic properties of the xenografts were tested to ensure that initial in vitro data might later be transferred to in vivo data. In parallel, three inhibitors of tumor cell metabolism, 2-deoxy-D-glucose, an inhibitor of glycolysis, oxamate, a pyruvate analogue and inhibitor of lactate dehydrogenase, and rotenone, a specific inhibitor of mitochondrial electron complex I, were tested for their effect on the metabolism and radio-sensitivity of the respective ovarian cancer-derived cell lines.

RESULTS

We found that all three inhibitors tested led to significant changes in the tumor cell energy metabolism at non-cytotoxic concentrations. Furthermore, we found that inhibition of tumor glycolysis by 2-deoxy-D-glucose in combination with rotenone decreased the radio-resistance at a clinically relevant radiation dose. This apparent radio-sensitizing effect appears to be based on an increased level of double strand DNA breaks 1 h and 24 h after gamma irradiation. Both cancer-derived cell lines maintained their metabolic properties, as well as their protein expression profiles and levels of reactive oxygen species in xenografts, thus providing a suitable model system for further in vivo investigations.

CONCLUSION

A combination of metabolic inhibitors and reactive oxygen species-generating therapies, such as irradiation, may effectively enhance the therapeutic response in particularly metabolically highly active (ovarian) tumors.

Role of pharmacogenetics of drug-metabolizing enzymes in treating osteosarcoma

INTRODUCTION

Drug-metabolizing enzymes (DMEs) biotransform several toxins and xenobiotics in both tumor and normal cells, resulting in either their detoxification or their activation. Since DMEs also metabolize several chemotherapeutic drugs, they can significantly influence tumor response to chemotherapy and susceptibility of normal tissues to collateral toxicity of anticancer treatments.

AREAS COVERED

This review discusses the pharmacogenetics of DMEs involved in the metabolism of drugs which constitute the backbone of osteosarcoma (OS) chemotherapy, highlighting what is presently known for this tumor and their possible impact on the modulation of future treatment approaches.

EXPERT OPINION

Achieving further insight into pharmacogenetic markers and biological determinants related to treatment response in OS may ultimately lead to individualized treatment regimens, based on a combination of genotype and tumor characteristics of each patient.

In vitro effects of some flavones on human pyruvate kinase isoenzyme M2

PKM2 is an important target for designing anticancer drug. Inhibitors and activators of this enzyme are suitable molecules for use in treating cancer. The aim of the present study was to investigate the effect of certain flavones on PKM2. Apigenin, wogonin, flavone, 3-hydroxyflavone, 5-hydroxyflavone, 6-hydroxyflavone, and 7-hydroxyflavone effectively inhibited PKM2, with IC50 in the range of 0.99-2.120 μM. The kinetic study indicated that these compounds acted as noncompetitive with Ki values of 3.53-5.67 μM toward phosphoenolpyruvate. Scutellarin and tangeritin demonstrated strong activation effect with AC50 values < 2 μM. Diosmetin, baicalin, baicalein, and luteolin showed an intermediate-level activator effect. These results demonstrate that flavone and their analogs could serve as leading compounds to develop new potent and selective inhibitor and activator for PKM2.

The function of the respiratory supercomplexes: the plasticity model

Mitochondria are important organelles not only as efficient ATP generators but also in controlling and regulating many cellular processes. Mitochondria are dynamic compartments that rearrange under stress response and changes in food availability or oxygen concentrations. The mitochondrial electron transport chain parallels these rearrangements to achieve an optimum performance and therefore requires a plastic organization within the inner mitochondrial membrane. This consists in a balanced distribution between free respiratory complexes and supercomplexes. The mechanisms by which the distribution and organization of supercomplexes can be adjusted to the needs of the cells are still poorly understood. The aim of this review is to focus on the functional role of the respiratory supercomplexes and its relevance in physiology. This article is part of a Special Issue entitled: Dynamic and ultrastructure of bioenergetic membranes and their components.

TIGAR is correlated with maximal standardized uptake value on FDG-PET and survival in non-small cell lung cancer

OBJECTIVE

Evaluation of (18)F-FDG uptake value via PET is central to current methods of diagnosis and staging of non-small cell lung cancer (NSCLC) due to its ability to evaluate expression levels of key regulators associated with glucose metabolism in tumor cells. Tp53-induced glycolysis and apoptosis regulator (TIGAR) is an important P53-induced protein that can inhibit glycolysis; however, there have been few clinical studies on its mechanism. Here we have investigated the relationship between TIGAR expression and (18)F-FDG PET in tumors, along with its relationship with the clinical characteristics of NSCLC.

METHODS

We analyzed SUVmax in 79 patients with NSCLC through immunohistochemical staining of TIGAR and five other biological markers associated with tumor cell glycolysis, in order to evaluate the correlation between their expression and SUVmax. We also plotted Kaplan-Meier survival curves to assess TIGAR expression with the prognosis and survival of patients with NSCLC.

RESULTS

The key findings were as follows: SUVmax was negatively correlated with the expression of TIGAR (r = -0.31, p<0.01); TIGAR expression was correlated with tumor size (p = 0.01), histological type (p<0.01), differentiation degree (p<0.01) and lymph node metastasis(p<0.01) in patients with NSCLC; and the survival time of patients whose TIGAR was negatively expressed was significantly shorter than for those whose TIGAR was positively expressed (P = 0.023).

CONCLUSIONS

The expression of TIGAR in primary tumors is significantly correlated with SUVmax, and low expression of TIGAR may predict a worse clinical outcome in patients with NSCLC.

Genome-scale modeling of human metabolism - a systems biology approach

Altered metabolism is linked to the appearance of various human diseases and a better understanding of disease-associated metabolic changes may lead to the identification of novel prognostic biomarkers and the development of new therapies. Genome-scale metabolic models (GEMs) have been employed for studying human metabolism in a systematic manner, as well as for understanding complex human diseases. In the past decade, such metabolic models - one of the fundamental aspects of systems biology - have started contributing to the understanding of the mechanistic relationship between genotype and phenotype. In this review, we focus on the construction of the Human Metabolic Reaction database, the generation of healthy cell type- and cancer-specific GEMs using different procedures, and the potential applications of these developments in the study of human metabolism and in the identification of metabolic changes associated with various disorders. We further examine how in silico genome-scale reconstructions can be employed to simulate metabolic flux distributions and how high-throughput omics data can be analyzed in a context-dependent fashion. Insights yielded from this mechanistic modeling approach can be used for identifying new therapeutic agents and drug targets as well as for the discovery of novel biomarkers. Finally, recent advancements in genome-scale modeling and the future challenge of developing a model of whole-body metabolism are presented. The emergent contribution of GEMs to personalized and translational medicine is also discussed.

Targeting cell cycle regulation in cancer therapy

Cell proliferation is an essential mechanism for growth, development and regeneration of eukaryotic organisms; however, it is also the cause of one of the most devastating diseases of our era: cancer. Given the relevance of the processes in which cell proliferation is involved, its regulation is of paramount importance for multicellular organisms. Cell division is orchestrated by a complex network of interactions between proteins, metabolism and microenvironment including several signaling pathways and mechanisms of control aiming to enable cell proliferation only in response to specific stimuli and under adequate conditions. Three main players have been identified in the coordinated variation of the many molecules that play a role in cell cycle: i) The cell cycle protein machinery including cyclin-dependent kinases (CDK)-cyclin complexes and related kinases, ii) The metabolic enzymes and related metabolites and iii) The reactive-oxygen species (ROS) and cellular redox status. The role of these key players and the interaction between oscillatory and non-oscillatory species have proved essential for driving the cell cycle. Moreover, cancer development has been associated to defects in all of them. Here, we provide an overview on the role of CDK-cyclin complexes, metabolic adaptations and oxidative stress in regulating progression through each cell cycle phase and transitions between them. Thus, new approaches for the design of innovative cancer therapies targeting crosstalk between cell cycle simultaneous events are proposed.

Kinetic modeling of hyperpolarized (13)C pyruvate metabolism in tumors using a measured arterial input function

Mathematical models are required to estimate kinetic parameters of [1-(13)C] pyruvate-lactate interconversion from magnetic resonance spectroscopy data. One- or two-way exchange models utilizing a hypothetical approximation to the true arterial input function (AIF), (e.g. an ideal 'box-car' function) have been used previously. We present a method for direct measurement of the AIF in the rat. The hyperpolarized [1-(13)C] pyruvate signal was measured in arterial blood as it was continuously withdrawn through a small chamber. The measured signal was corrected for T1 relaxation of pyruvate, RF pulses and dispersion of blood in the chamber to allow for the estimation of the direct AIF. Using direct AIF, rather than the commonly used box-car AIF, provided realistic estimates of the rate constant of conversion of pyruvate to lactate, kpl, the rate constant of conversion of lactate to pyruvate klp, the clearance rate constant of pyruvate from blood to tissue, Kip, and the relaxation rate of lactate T1la. Since no lactate signal was present in blood, it was possible to use a simple precursor-product relationship, with the tumor tissue pyruvate time-course as the input for the lactate time-course. This provided a robust estimate of kpl, similar to that obtained using a directly measured AIF.

Obesity, type 2 diabetes, and cancer: the insulin and IGF connection

Epidemiological studies suggest a positive association between obesity and type 2 diabetes mellitus (T2D) with the risk of cancer and cancer-related mortality. Insulin resistance, hyperinsulinemia, increased levels of IGF, elevated levels of steroid and peptide hormones, and inflammatory markers appear to play a role in the connection between these different diseases. Medications, such as metformin and exogenous insulin, used to treat T2D may affect the risk of cancer and cancer-related mortality. Newer therapies targeting the insulin and IGF1 systems are being developed for use in cancer therapy.

Energy metabolism, proteotoxic stress and age-related dysfunction - protection by carnosine

This review will discuss the relationship between energy metabolism, protein dysfunction and the causation and modulation of age-related proteotoxicity and disease. It is proposed that excessive glycolysis, rather than aerobic (mitochondrial) activity, could be causal to proteotoxic stress and age-related pathology, due to the generation of endogenous glycating metabolites: the deleterious role of methylglyoxal (MG) is emphasized. It is suggested that TOR inhibition, exercise, fasting and increased mitochondrial activity suppress formation of MG (and other deleterious low molecular weight carbonyl compounds) which could control onset and progression of proteostatic dysfunction. Possible mechanisms by which the endogenous dipeptide, carnosine, which, by way of its putative aldehyde-scavenging activity, may control age-related proteotoxicity, cellular dysfunction and pathology, including cancer, are also considered. Whether carnosine could be regarded as a rapamycin mimic is briefly discussed.

The Amazing Power of Cancer Cells to Recapitulate Extraembryonic Functions: The Cuckoo's Tricks

Inflammation is implicated in tumor development, invasion, and metastasis. Hence, it has been suggested that common cellular and molecular mechanisms are activated in wound repair and in cancer development. In addition, it has been previously proposed that the inflammatory response, which is associated with the wound healing process, could recapitulate ontogeny through the reexpression of the extraembryonic, that is, amniotic and vitelline, functions in the interstitial space of the injured tissue. If so, the use of inflammation by the cancer-initiating cell can also be supported in the ability to reacquire extraembryonic functional axes for tumor development, invasion, and metastasis. Thus, the diverse components of the tumor microenvironment could represent the overlapping reexpression of amniotic and vitelline functions. These functions would favor a gastrulation-like process, that is, the creation of a reactive stroma in which fibrogenesis and angiogenesis stand out.