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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.

Metabolic reprogramming, a crucial cancer hallmark, shifts metabolic pathways such as glycolysis, tricarboxylic acid cycle or lipogenesis, to enable the growth characteristics of cancer cells. Here, we provide evidence that transketolase-like 1 (TKTL1) orchestrates aerobic glycolysis, fatty acid and nucleic acid synthesis, glutamine metabolism, protection against oxidative stress and cell proliferation. Furthermore, silencing of TKTL1 reduced the levels of sphingolipids such as lactosylceramide (a sphingolipid regulating cell survival, proliferation and angiogenesis) and phosphatidylinositol (which activates PI3K/Akt/mTOR signaling). Thus, in addition to its well-known roles in glucose and amino acid metabolism, TKTL1 also regulates lipid metabolism. In conclusion, our study provides unprecedented evidence that TKTL1 plays central roles in major metabolic processes subject to reprogramming in cancer cells and thus identifies TKTL1 as a promising target for new anti-cancer therapies., This work was supported by grants to M.C. (Agència de Gestió d’Ajuts Universitaris i de Recerca (AGAUR) – Generalitat de Catalunya, 2014SGR1017; ICREA Academia from the ICREA foundation; and MINECO-European Commission FEDER – Una manera de hacer Europa, SAF2014-56059-R), T.M.T. (MINECO-European Commission FEDER – Una manera de hacer Europa, SAF2015-66984-C2-1-R; and Xarxa de Referència en Biotecnologia) and P.C. (Research Foundation-Flanders (FWO), Belgian Science Policy grant (IUAP P7/03); long-term structural Methusalem funding by the Flemish Government; European Research Council (ERC) Advanced Research Grant (EU-ERC269073); and AXA Research Fund).

The study examines plasma metabolic profiles of patients with chronic obstructive pulmonary disease (COPD) to prove whether the disease influences metabolism at rest and after endurance training. This is based on the hypothesis that metabolome levels should reflect impaired skeletal muscle bioenergetics in COPD. The study aims to test this hypothesis by evaluating plasma metabolic profiles in COPD patients before and after 8 weeks of endurance exercise training. We studied blood samples from 18 COPD patients and 12 healthy subjects. Pre- and post-training blood plasma samples at rest and after constant-work rate exercise (CWRE) at 70% of pre-training Watts peak were analyzed by 1H-nuclear magnetic resonance spectroscopy to assess metabolite profiles. The two groups presented training-induced physiological changes in the VO2 peak and in blood lactate levels (P < 0.01 each). Before training, the two groups also showed differences in metabolic profiles at rest (P < 0.05). Levels of valine (r = 0.51, P < 0.01), alanine (r = 0.45, P < 0.05) and isoleucine (r = 0.51, P < 0.01) were positively associated with body composition (Fat Free Mass Index). While training showed a significant impact on the metabolic profile in healthy subjects (P < 0.001), with changes in levels of amino acids, creatine, succinate, pyruvate, glucose and lactate (P < 0.05 each), no equivalent training-induced effects were seen in COPD patients in whom only lactate decreased (P < 0.05). This study shows that plasma metabolic profiling contributes to the phenotypic characterization of COPD patients.

Cell cycle regulation is dependent on multiple cellular and molecular events. Cell proliferation requires metabolic sources for the duplication of DNA and cell size. However, nucleotide reservoirs are not sufficient to support cell duplication and, therefore, biosynthetic pathways should be upregulated during cell cycle. Here, we reveal that glucose-6-phosphate dehydrogenase (G6PDH) and transketolase (TKT), the 2 key enzymes of oxidative and nonoxidative branches of the pentose phosphate pathway (PPP), respectively, which is necessary for nucleotide synthesis, are enhanced during cell cycle progression of the human colon cancer cell line HT29. These enhanced enzyme activities coincide with an increased ratio of pentose monophosphate to hexose monophosphate pool during late G1 and S phase, suggesting a potential role for pentose phosphates in proliferating signaling. Isotopomeric analysis distribution of nucleotide ribose synthesized from 1,2-(13)C(2)-glucose confirms the activation of the PPP during late G1 and S phase and reveals specific upregulation of the oxidative branch. Our data sustain the idea of a critical oxidative and nonoxidative balance in cancer cells, which is consistent with a late G1 metabolic check point. The distinctive modulation of these enzymes during cell cycle progression may represent a new strategy to inhibit proliferation in anticancer treatments.

The quantitative understanding of the role of sugar phosphates in regulating tumor energetic metabolism at the proteomic and genomic level is a prerequisite for an efficient rational design in combined drug chemotherapy. Therefore, it is necessary to determine accurately the concentration of the main sugar phosphate pools at the lower concentrations present in the often-limited volume of tumor cell samples. Taking as an example the human adenocarcinoma cell line HT29, we here report a fast and reliable quantitative method based on the use of liquid nitrogen, a weak acid extraction, and liquid chromatography-electrospray ionization tandem mass spectrometry to quantify simultaneously the intracellular concentration of sugar phosphate pools. The method was set up using standard addition curves. Thus, it is possible to identify and quantify hexose phosphate, pentose phosphate, and triose phosphate pools up to 0.02-0.10 ng x microL(-1), depending on the analyte. The method developed was here used for the quantitative study of changes in phosphorylated carbohydrates of central carbon metabolism when high or low glucose concentration conditions are induced in vitro in the HT29 human colon adenocarcinoma cell line.

The pentose phosphate pathway plays a pivotal role in cellular physiology. It synthesizes the nucleotide precursor ribose-5-phosphate and NADPH, required for redox homeostasis maintenance and lipogenesis. Cancer cells undergo metabolic reprogramming required to sustain proliferation and fully achieve malignant capabilities. Such metabolic reprogramming involves multiple metabolic pathways, and the pentose phosphate pathway becomes essential in tumour metabolism and biology. According to that, many changes occur in this metabolic pathway over the tumorigenic process, and the enzymes in this pathway become directly involved in the metabolism of cancer cells as well as in other important features of tumours. Also, a greater reliance on this pathway has been detected in some types of tumours. In this chapter, a detailed view of the role of the pentose phosphate pathway and its enzymes in tumour metabolism is provided. In addition, the potentiality of this pathway as therapeutic target in cancer treatment is discussed.

Glucose-6-phosphate dehydrogenase (G6PDH) is an essential enzyme involved in the first reaction of the oxidative branch of the pentose phosphate pathway (PPP). Recently, G6PDH was suggested as a novel target protein for cancer therapy as one of the final products of the PPP, ribose-5-phosphate, is necessary for nucleic acid synthesis and tumor progression. After analyzing the protein–protein interface of the crystal structure of human G6PDH by means of molecular dynamics simulations, we designed six interface peptides based on the natural sequence of the protein. The three most promising peptides, as predicted by binding free energy calculations, were synthesized and one of them was confirmed as a novel inhibitor of human G6PDH in experimental assays. Together, the active peptide found and its suggested binding mode proposes a new strategy for inhibiting this enzyme and should aid the further design of novel, potent and non-peptidic G6PDH inhibitors.

Glioblastoma (GBM) is associated with infiltration of peritumoral (PT) parenchyma by isolated tumor cells that leads to tumor regrowth. Recently, GBM stem-like or initiating cells (GICs) have been identified in the PT area, but whether these GICs have enhanced migratory and invasive capabilities compared with GICs from the tumor mass (TM) is presently unknown. We isolated GICs from the infiltrated PT tissue and the TM of three patients and found that PT cells have an advantage over TM cells in two-dimensional and three-dimensional migration and invasion assays. Interestingly, PT cells display a high plasticity in protrusion formation and cell shape and their migration is insensitive to substrate stiffness, which represent advantages to infiltrate microenvironments of different rigidity. Furthermore, mouse and chicken embryo xenografts revealed that only PT cells showed a dispersed distribution pattern, closely associated to blood vessels. Consistent with cellular plasticity, simultaneous Rac and RhoA activation are required for the enhanced invasive capacity of PT cells. Moreover, Rho GTPase signaling modulators αVβ3 and p27 play key roles in GIC invasiveness. Of note, p27 is upregulated in TM cells and inhibits RhoA activity. Gene silencing of p27 increased the invasive capacity of TM GICs. Additionally, β3 integrin is upregulated in PT cells. Blockade of dimeric integrin αVβ3, a Rac activator, reduced the invasive capacity of PT GICs in vitro and abrogated the spreading of PT cells into chicken embryos. Thus, our results describe the invasive features acquired by a unique subpopulation of GICs that infiltrate neighboring tissue.

Carbohydrate response element-binding protein (ChREBP) is a transcription factor that mediates glucose signaling in mammalian liver, leading to the expression of different glycolytic and lipogenic genes, such as pyruvate kinase (L-PK) and fatty acid synthase (FAS). The current model for ChREBP activation in response to sugar phosphates holds that glucose metabolization to xylulose 5-phosphate (X-5-P) triggers the activation of protein phosphatase 2A, which dephosphorylates ChREBP and leads to its nuclear translocation and activation. However, evidence indicates that glucose 6-phosphate (G-6-P) is the most likely signal metabolite for the glucose-induced transcription of these genes. The glucose derivative that is responsible for carbohydrate-dependent gene expression remains to be identified. The difficulties in measuring G-6-P and X-5-P concentrations simultaneously and in changing them independently have hindered such identification. To discriminate between these possibilities, we adapted a liquid chromatography mass spectrometry method to identify and quantify sugar phosphates in human hepatocarcinoma cells (Hep G2) and rat hepatocytes in response to different carbon sources and in the presence/absence of a glucose-6-phosphate dehydrogenase inhibitor. We also used this method to demonstrate that these cells could not metabolize 2-deoxyglucose beyond 2-deoxyglucose-6-phosphate. The simultaneous quantification of sugar phosphates and FAS and L-PK expression levels demonstrated that both X-5-P and G-6-P play a role in the modulation of gene expression. In conclusion, this report presents for the first time a single mechanism that incorporates the effects of X-5-P and G-6-P on the enhancement of the expression of carbohydrate-responsive genes. © 2012 the American Physiological Society., This study was supported by the projects SAF2009-12602 and SAF2011-25726 and by RD06/0020/0046 and RD06/0014/0025 from Red Temática de Investigación Cooperativa en Cáncer and Red de Centros FIS-RECAVA, respectively, from the Instituto de Salud Carlos III, both funded by the Ministerio de Ciencia e Innovación-Spanish government and European Regional Development Funds “Una manera de hacer Europa.” It has also received financial support from the European Union-funded project ETHERPATHS (FP7-KBBE-222639) (http://www.etherpaths.org/) and from the Agència de Gestió d'Ajuts Universitaris i de Recerca-Generalitat de Catalunya (2009SGR01308, 2006ITT-10007, and 2009CTP-00026).

Strategies targeting pathological angiogenesis have focused primarily on blocking vascular endothelial growth factor (VEGF), but resistance and insufficient efficacy limit their success, mandating alternative antiangiogenic strategies. We recently provided genetic evidence that the glycolytic activator phosphofructokinase-2/fructose-2,6-bisphosphatase 3 (PFKFB3) promotes vessel formation but did not explore the antiangiogenic therapeutic potential of PFKFB3 blockade. Here, we show that blockade of PFKFB3 by the small molecule 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO) reduced vessel sprouting in endothelial cell (EC) spheroids, zebrafish embryos, and the postnatal mouse retina by inhibiting EC proliferation and migration. 3PO also suppressed vascular hyperbranching induced by inhibition of Notch or VEGF receptor 1 (VEGFR1) and amplified the antiangiogenic effect of VEGF blockade. Although 3PO reduced glycolysis only partially and transiently in vivo, this sufficed to decrease pathological neovascularization in ocular and inflammatory models. These insights may offer therapeutic antiangiogenic opportunities. publisher: Elsevier articletitle: Partial and Transient Reduction of Glycolysis by PFKFB3 Blockade Reduces Pathological Angiogenesis journaltitle: Cell Metabolism articlelink: http://dx.doi.org/10.1016/j.cmet.2013.11.008 content_type: article copyright: Copyright © 2014 Elsevier Inc. All rights reserved. ispartof: CELL METABOLISM vol:19 issue:1 pages:37-48 ispartof: location:United States status: published