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The carbohydrate metabolism of certain pathological overgrowths

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... Crabtree demonstrated that this type of metabolism is not limited to cancer cells and is a common feature of "pathological overgrowths", although he did not specify the exact mechanisms at that time. (16) He referred to Warburg and explained again that glycolytic rate (fermentation) was much higher than subsequent oxidation/respiration in the TCA-cycle. More recent studies show that high glycolytic rates serve the synthesis of cancerous tissues and the authors suggest that this may also apply in non-cancerous states, but did not further expand on this suggestion. ...
... The genes steering the glucose sparing effect of insulin resistance, may have survived through evolution because the period is prolonged during which the Cori cycle, Warburg and Crabtree effects can play an anabolic role and thereby promote survival. (16) So far, the changes in glucose, fat and protein metabolism, that were outlined in the previous paragraphs, occur in all conditions of stress, cancer and growth and require inflammation induced insulin resistance. (73) The evidence, that we have presented with respect to net substrate exchange, provides insight regarding the way in which the anaplerotic/cataplerotic effects of the Cori-cycle, the TCA-cycle, the pentose phosphate pathway and other cycles support the production of a suitable substrate mix supporting cell proliferation and matrix synthesis. ...
... Although Crabtree demonstrated that the Warburg effect was not restricted to cancer and was associated with growth, he did not specify how increased glycolytic rates contribute to growth, but merely focused on the production of lactate, ethanol and other products of fermentation. (16) J o u r n a l P r e -p r o o f ...
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In evolution, genes survived that could code for metabolic pathways, promoting long term survival during famines or fasting when suffering from trauma, disease or during physiological growth. This requires utilization of substrates, already present in some form in the body. Carbohydrate stores are limited and to survive long, their utilization is restricted to survival pathways, by inhibiting glucose oxidation and glycogen synthesis. This leads to insulin resistance and spares muscle protein, because being the main supplier of carbon for new glucose production. In these survival pathways, part of the glucose is degraded in glycolysis in peripheral (muscle) tissues to pyruvate and lactate (Warburg effect), which are partly reutilized for glucose formation in liver and kidney, completing the Cori-cycle. Another part of the glucose taken up by muscle contributes, together with muscle derived amino acids, to the production of substrates consisting of a complete amino acid mix but extra non-essential amino acids like glutamine, alanine, glycine and proline. These support cell proliferation, matrix deposition and redox regulation in tissues, specifically active in host response and during growth. In these tissues, also glucose is taken up delivering glycolytic intermediates, that branch off and act as building blocks and produce reducing equivalents. Lactate is also produced and released in the circulation, adding to the lactate released by muscle in the Cori-cycle and completing secondary glucose cycles. Increased fluxes through these cycles lead to modest hyperglycemia and hyperlactatemia in states of healthy growth and disease and are often misinterpreted as induced by hypoxia.
... The SAM effect could impact on the metabolism of neoplastic cells, characterized by active glycolysis even in aerobiosis [Warburg effect (95)]. The respiratory activity of neoplastic liver cells, comparable to that of normal cells in absence of glucose, is highly restrained after glucose addition (96)(97)(98). This mainly depends on a decreased availability of intracellular ADP, largely used for synthesis of glycolytic ATP, that limits oxygen consumption (97). ...
... MYC and AKT activate hexokinase II, MYC and HIF-1α activate glucose transport, pyruvate kinase and lactate dehydrogenase; pyruvate kinase is also activated by RAS, and AKT activates glucose transport (102)(103)(104). Moreover, HSF-1α and MYC trigger pyruvate dehydrogenase kinase that, by activating pyruvate dehydrogenase, impedes the synthesis of acetyl-CoA (102), thus contributing to maintain low the respiratory activity of cancer cells in the presence of glucose (96)(97)(98). The activation of glucose-6-phosphate dehydrogenase, by HSF-1α, provides pentose phosphates for nucleic acids synthesis (105,106). ...
... De acordo com Monot et al. (1982), o C. acetobutylicum necessitam de, no mínimo, 40 g/L de glicose inicial para existirem as fases de acidogênese e solventogênese e produzir n-butanol. Este fenômeno está em acordo com o efeito Crabtree positivo (Crabtree, 1928), no qual altas concentrações do substrato ativam uma rota metabólica. No entanto, o metabolismo desta linhagem ainda não foi totalmente elucidado. ...
... Entretanto, a produção de biomassa celular foi a mesma para os dois processos. A produção de 1-butanol foi maior no experimento em que se usou 40 g/L de glicerol inicial, reforçando a hipótese do efeito Crabtree positivo (Crabtree, 1928) neste processo, similar ao processo com a cepa C. acetobutylicum, que necessitam de, no mínimo, 40 g/L de glicose inicial para existirem as fases de acidogênese e solventogênese e produzir n-butanol, de acordo com Monot et al. (1982). No entanto, verifica-se que diferentes metabólitos em diferentes concentrações foram produzidos nos dois processos. ...
... The SAM effect could impact on the metabolism of neoplastic cells, characterized by active glycolysis even in aerobiosis [Warburg effect (95)]. The respiratory activity of neoplastic liver cells, comparable to that of normal cells in absence of glucose, is highly restrained after glucose addition (96)(97)(98). This mainly depends on a decreased availability of intracellular ADP, largely used for synthesis of glycolytic ATP, that limits oxygen consumption (97). ...
... MYC and AKT activate hexokinase II, MYC and HIF-1α activate glucose transport, pyruvate kinase and lactate dehydrogenase; pyruvate kinase is also activated by RAS, and AKT activates glucose transport (102)(103)(104). Moreover, HSF-1α and MYC trigger pyruvate dehydrogenase kinase that, by activating pyruvate dehydrogenase, impedes the synthesis of acetyl-CoA (102), thus contributing to maintain low the respiratory activity of cancer cells in the presence of glucose (96)(97)(98). The activation of glucose-6-phosphate dehydrogenase, by HSF-1α, provides pentose phosphates for nucleic acids synthesis (105,106). ...
Article
The under-regulation of liver-specific MAT1A gene codifying for S-adenosylmethionine (SAM) synthesizing isozymes MATI/III, and the up-regulation of widely expressed MAT2A, MATII isozyme occurs in hepatocellular carcinoma (HCC). MATα1:MATα2 switch strongly contributes to the fall in SAM liver content both in rodent and human liver carcinogenesis. SAM administration to carcinogen-treated animals inhibits hepatocarcinogenesis. The opposite occurs in Mat1a-KO mice, in which chronic SAM deficiency is followed by HCC development. This review focuses upon the changes, induced by the MATα1:MATα2 switch, involved in HCC development. In association with MATα1:MATα2 switch there occurs, in HCC, global DNA hypomethylation, decline of DNA repair, genomic instability, and deregulation of different signaling pathways such as overexpression of c-MYC (avian myelocytomatosis viral oncogene homolog), increase of polyamine (PA) synthesis and RAS/ERK (Harvey murine sarcoma virus oncogene homolog/extracellular signal-regulated kinase), IKK/NF-kB (I-k kinase beta/nuclear factor kB), PI3K/AKT, and LKB1/AMPK axes. Furthermore, a decrease in MATα1 expression and SAM level induces HCC cell proliferation and survival. SAM treatment in vivo and enforced MATα1 overexpression or MATα2 inhibition, in cultured HCC cells, prevent these changes. A negative correlation of MATα1:MATα2 and MATI/III:MATII ratios with cell proliferation and genomic instability and a positive correlation with apoptosis and global DNA methylation are present in human HCC. Altogether, these data suggest that the decrease of SAM level and the deregulation of MATs are potential therapeutic targets for HCC.
... Also. it is more difficult in multicellular organisms to define such a cellular objective. 7. Standard FBA was not able to explain some important phenomena related to metabolism like the Crabtree effect [45], Warburg effect [46], overflow metabolism [47], the order of different carbon source consumption, and cross-feeding [48]. ...
... One of the major strengths of FBA is that it can predict many phenotypes correctly without requiring knowledge on enzyme kinetics. However, there are a range of metabolic phenomena that cannot be modeled in this framework, such as the Warburg effect observed in many cancer cell lines [46,98] and the Crabtree effect in yeast cells grown on abundant glucose [45], or the evolution of crossfeeding in originally monoclonal bacterial populations [48]. Such phenomena are likely a result of compromises in proteome allocation due to the limited solvent capacity of the cell [99,100]; their explanation requires the inclusion of enzyme kinetics and cellular volume (or concentration) constraints into FBA. ...
Thesis
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Constraint-based metabolic modeling methods such as Flux Balance Analysis (FBA) are routinely used to predict metabolic phenotypes, e.g., growth rates, ATP yield, or the fitness of gene knockouts. While powerful, FBA has some important limitations. For example, FBA solutions are not unique and can contain thermodynamically infeasible cycles. FBA ignores gene regulation, and thus FBA solutions may not be compatible with experimentally determined gene expression states. Crucially, FBA ignores important biological constraints, such as limits imposed by the finite cell volume on protein counts, a phenomenon often termed molecular crowding. In this thesis, I introduce three different ways to improve Flux Balance Analysis predictions. The first improvement eliminates thermodynamically infeasible cycles. It is based on a fast postprocessing step for constraint-based solutions. The algorithm, termed CycleFreeFlux, removes internal cycles from any given flux distribution v(0) without disturbing other fluxes not involved in the cycles. It works by minimizing the sum of absolute fluxes ||v||1 while (i) conserving the exchange fluxes and (ii) using the fluxes of the original solution to bound the new flux distribution. This strategy reduces internal fluxes until at least one reaction of every possible internal cycle is inactive, a necessary and sufficient condition for the thermodynamic feasibility of a flux distribution. If alternative representations of the input flux distribution in terms of elementary flux modes exist that differ in their inclusion of internal cycles, then CycleFreeFlux is biased towards solutions that maintain the direction given by v(0) and towards solutions with lower total flux ||v||1. My method requires only one additional linear optimization, making it computationally very efficient compared to alternative strategies. The second improvement of FBA, termed ccFBA (for capacity-constrained flux balance analysis), provides a framework to convert any complete FBA model into a model for metabolic modeling with enzyme kinetics (MOMENT) that accounts for molecular crowding. I provide an improved implementation of a molecular crowding model for E. coli and the first such implementation for the yeast Saccharomyces cerevisiae. ccFBA is an extension to sybil, a library for efficient constraint-based modeling in the R environment for statistical computing. ccFBA improves the original implementation of MOMENT by partitioning multifunctional enzymes between the different reactions that they catalyze. Although the improved E. coli implementation includes kinetic constants for 117 additional reactions, predicted E. coli growth rates across different carbon sources still show much less variation than observed experimentally; this discrepancy is likely due to the condition-dependent expression of proteins in preparation for environmental changes, an important but as yet poorly understood element of microbial metabolism. Finally, I introduce three novel methods that use transcriptomic and/or proteomic data to predict metabolic fluxes on a genome scale. The first of these methods is called FECorr. FECorr fits piecewise linear functions to the experimentally observed relationship between gene expression and possible flux ranges determined from simulations. To do this, it utilizes gene expression from multiple experiments. The flux distributions predicted from these functions show better agreement with measured metabolic fluxes than all other gene expression methods compared in a previous benchmark study. The second method I introduce in the final part of the thesis is called ATM-FBA. It automatically identifies optimal thresholds to distinguish active from non-active genes and reactions. ATM-FBA also performs slightly better than previously published gene expression methods. The third new method is termed eFBA-gene. Similar to other methods, it uses a constant threshold as input and formulates a mixed-integer linear programming (MILP) problem with the objective to minimize the discrepancy between expression data and predicted flux distributions. However, in contrast to other expression-based methods, eFBA-gene scores the agreement between simulated fluxes and expression data not on a per-reaction basis, but on a per-gene basis. For some combinations of gene expression threshold and flux threshold, eFBA-gene also outperforms other gene expression methods.
... It is well known that the high glucose consumption by cancer cells is associated with a restraint of oxygen consumption and lactic acid production in aerobiosis [136][137][138]. This does not seem to depend on functional alterations of tumor mitochondria. ...
Article
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Several researchers have analyzed the alterations of the methionine cycle associated with liver disease to clarify the pathogenesis of human hepatocellular carcinoma (HCC) and improve the preventive and the therapeutic approaches to this tumor. Different alterations of the methionine cycle leading to a decrease of S-adenosylmethionine (SAM) occur in hepatitis, liver steatosis, liver cirrhosis, and HCC. The reproduction of these changes in MAT1A-KO mice, prone to develop hepatitis and HCC, demonstrates the pathogenetic role of MAT1A gene under-regulation associated with up-regulation of the MAT2A gene (MAT1A:MAT2A switch), encoding the SAM synthesizing enzymes, methyladenosyltransferase I/III (MATI/III) and methyladenosyltransferase II (MATII), respectively. This leads to a rise of MATII, inhibited by the reaction product, with a consequent decrease of SAM synthesis. Attempts to increase the SAM pool by injecting exogenous SAM have beneficial effects in experimental alcoholic and non-alcoholic steatohepatitis and hepatocarcinogenesis. Mechanisms involved in hepatocarcinogenesis inhibition by SAM include: (1) antioxidative effects due to inhibition of nitric oxide (NO•) production, a rise in reduced glutathione (GSH) synthesis, stabilization of the DNA repair protein Apurinic/Apyrimidinic Endonuclease 1 (APEX1); (2) inhibition of c-myc, H-ras, and K-ras expression, prevention of NF-kB activation, and induction of overexpression of the oncosuppressor PP2A gene; (3) an increase in expression of the ERK inhibitor DUSP1; (4) inhibition of PI3K/AKT expression and down-regulation of C/EBPα and UCA1 gene transcripts; (5) blocking LKB1/AMPK activation; (6) DNA and protein methylation. Different clinical trials have documented curative effects of SAM in alcoholic liver disease. Furthermore, SAM enhances the IFN-α antiviral activity and protects against hepatic ischemia-reperfusion injury during hepatectomy in HCC patients with chronic hepatitis B virus (HBV) infection. However, although SAM prevents experimental tumors, it is not curative against already established experimental and human HCCs. The recent observation that the inhibition of MAT2A and MAT2B expression by miRNAs leads to a rise of endogenous SAM and strong inhibition of cancer cell growth could open new perspectives to the treatment of HCC.
... Carbon overflow is a metabolic response to diverse stimuli and, in the most prominent example, is described by the Warburg effect where respiring healthy mammalian cells shift metabolism to fermentation in cancer cells (Warburg, 1956). However, a different mechanism results carbon overflow in the Crabtree effect wherein presence of excess glucose represses respiration allowing aerobic glycolysis to be the main source of energy supply in several species of yeast (Crabtree, 1928;De Deken, 1966). Besides biomass and carbon dioxide (CO 2 ) carbon overflow result in formation of metabolic byproducts such as organic acids in bacteria, ethanol in yeast and lactate in cancer cells (Vander Heiden et al., 2009). ...
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Central carbon metabolism produces energy and precursor metabolites for biomass in heterotrophs. Carbon overflow yields metabolic byproducts and, here, we examined its dependency on nutrient and growth using the unicellular eukaryotic model organism Saccharomyces cerevisiae. We performed quantitative proteomics analysis together with metabolic modeling and found that proteome overabundance enabled respiration, and variation in energy efficiency caused distinct composition of biomass at different carbon to nitrogen ratio and growth rate. Our results showed that ceullar resource allocation for ribosomes was determinative of growth rate, but energy constrains on protein synthesis incepted carbon overflow by prioritizing abundance of ribosomes and glycolysis over mitochondria. We proved that glycolytic efficiency affected energy metabolism by making a trade-off between low and high energy production pathways. Finally, we summarized cellular energy budget underlying nutrient-responsive and growth rate-dependent carbon overflow, and suggested implications of results for bioprocesses and pathways relevant in cancer metabolism in humans.
... In this study, using the colon cancer cells, we attempted to understand how high rates of OxPhos coincide with elevated glycolysis. Simultaneous glycolysis and OxPhos other than in tumor cells (Greenhouse & Lehninger, 1976;Spencer & Lehninger, 1976), have been described in embryos (Krisher & Prather, 2012;Lane & Gardner, 2005), heart (Safer, Smith, & Williamson, 1971), muscles and neurons (Gellerich et al., 2012;Schantz & Henriksson, 1987), beta cells (Rubi, del Arco, Bartley, Satrustegui, & Maechler, 2004), and warts (Crabtree, 1928), all conditions with high demand for energy equivalents and anabolic precursors for proliferation. The dependency of activity of both glycolysis and OxPhos on NAD + / NADH homeostasis suggests that the malate-aspartate shuttle (MAS) is important in synchronizing the cytosolic glycolytic pathway and mitochondrial OxPhos. ...
Article
Metabolism in cancer cells is rewired to generate sufficient energy equivalents and anabolic precursors to support high proliferative activity. Within the context of these competing drives aerobic glycolysis is inefficient for the cancer cellular energy economy. Therefore, many cancer types, including colon cancer, reprogram mitochondria‐dependent processes to fulfill their elevated energy demands. Elevated glycolysis underlying the Warburg effect is an established signature of cancer metabolism. However, there are a growing number of studies that show that mitochondria remain highly oxidative under glycolytic conditions. We hypothesized that activities of glycolysis and oxidative phosphorylation are coordinated to maintain redox compartmentalization. We investigated the role of mitochondria‐associated malate–aspartate and lactate shuttles in colon cancer cells as potential regulators that couple aerobic glycolysis and oxidative phosphorylation. We demonstrated that the malate–aspartate shuttle exerts control over NAD+/NADH homeostasis to maintain activity of mitochondrial lactate dehydrogenase and to enable aerobic oxidation of glycolytic l‐lactate in mitochondria. The elevated glycolysis in cancer cells is proposed to be one of the mechanisms acquired to accelerate oxidative phosphorylation. The elevated glycolysis in cancer cells is proposed to be one of the mechanisms acquired to accelerate oxidative phosphorylation. The mitochondrial malate–aspartate and lactate shuttles cooperate to enable aerobic oxidation of glycolytic l‐lactate in mitochondria.
... It prefers to ferment when glucose concentrations are high regardless of the presence of oxygen. This phenomenon is called the Crabtree effect, after the English biochemist Herbert Grace Crabtree [77]. Interestingly, it is a very similar phenomenon to the Warburg effect in cancer cells, where cancer cells tend to ferment glucose instead of respire in the presence of oxygen [78]. ...
Thesis
The natural environment of yeast is often a community of cells but researchers prefer to study them in simpler homogeneous environments like single cell or bulk liquid cultures, losing insight into complex spatiotemporal growth, differentiation and self-organization and how those features are intertwined and shaped through evolution and ecology. I developed a multi-layered microfluidic device that allows us to grow yeast colonies in spatially controlled dynamically structured changing environments from a monolayer of single yeast cells to a multi-layered colony. Colony growth, as a whole and at specific locations, is a result of the nutrient gradient formation within a colony through interplay of nutrient diffusion rates, nutrient uptake rates by the cells and starting nutrient concentrations. Once a limiting nutrient (e.g. glucose or amino acids) is depleted at a specific distance from the nutrients source the cells within a colony stop to grow. I was able to modulate this specific distance by changing the starting nutrient concentrations and uptake rates of cells. Colony gene expression patterns gave us information on specific micro environments formation and consequential development, differentiation and self-organization. I quantified the patterns of expression of seven glucose transporter genes (HXT1-7), each of them specifically expressed depending on the glucose concentration. This enabled us to reconstruct glucose gradients formation in a colony. I further followed the expression of fermentation and respiration specific genes and observed differentiation between two subpopulations. We also mapped other genes specific for different parts of carbohydrate metabolism, followed and quantified the spatiotemporal dynamics of growth and gene expression, and finally modelled the colony growth and nutrient gradient formation. For the first time, we were able to observe growth, differentiation and self-organization of S. cerevisiae colony with such an unprecedented spatiotemporal resolution
... As a result, partially oxidized molecules, rather than CO 2 , are excreted to the environment. This phenomenon was already observed for yeasts by Louis Pasteur in 1861 [1] and later on in muscle cells [2], carcinoma cells [3] and normal tissues after viral infection [4]. Traditionally referred to as the "Pasteur", "Warburg" and "Crabtree" effect, such a metabolic state is collectively known as overflow metabolism [5]. ...
Article
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Overflow metabolism is a phenomenon extended in nature, ranging from microbial to cancer cells. Accumulation of overflow metabolites pose a challenge for large-scale bioprocesses. Yet, the causes of overflow metabolism are not fully clarified. In this work, the underlying mechanisms, reasons and consequences of overflow metabolism in different organisms have been summarized. The reported effect of aerobic expression of Vitreoscilla haemoglobin (VHb) in different organisms are revised. The use of VHb to reduce overflow metabolism is proposed and studied through flux balance analysis in E. coli at a fixed maximum substrate and oxygen uptake rates. Simulations showed that the presence of VHb increases the growth rate, while decreasing acetate production, in line with the experimental measurements. Therefore, aerobic VHb expression is considered a potential tool to reduce overflow metabolism in cells.
... To examine the growth inhibitory effects of BAY 87-2243 treatment in the context of CHCHD4 loss, we used U2OS cells stably expressing either control shRNA or CHCHD4 shRNA (Fig. 5). We found that CHCHD4 (shRNA) knockdown led to significantly reduced tumour cell growth when cells were cultured in glucose-free (galactose-containing) media (Fig. 5a) which forces them to utilise the respiratory chain and produce ATP via OXPHOS [36]. Importantly, we found that CHCHD4 (shRNA) knockdown cells were significantly less sensitive to BAY 87-2243 treatment compared to control shRNA cells (Fig. 5b). ...
Article
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Background: Tumour cells rely on glycolysis and mitochondrial oxidative phosphorylation (OXPHOS) to survive. Thus, mitochondrial OXPHOS has become an increasingly attractive area for therapeutic exploitation in cancer. However, mitochondria are required for intracellular oxygenation and normal physiological processes, and it remains unclear which mitochondrial molecular mechanisms might provide therapeutic benefit. Previously, we discovered that coiled-coil-helix-coiled-coil-helix domain-containing protein 4 (CHCHD4) is critical for regulating intracellular oxygenation and required for the cellular response to hypoxia (low oxygenation) in tumour cells through molecular mechanisms that we do not yet fully understand. Overexpression of CHCHD4 in human cancers correlates with increased tumour progression and poor patient survival. Results: Here, we show that elevated CHCHD4 expression provides a proliferative and metabolic advantage to tumour cells in normoxia and hypoxia. Using stable isotope labelling with amino acids in cell culture (SILAC) and analysis of the whole mitochondrial proteome, we show that CHCHD4 dynamically affects the expression of a broad range of mitochondrial respiratory chain subunits from complex I-V, including multiple subunits of complex I (CI) required for complex assembly that are essential for cell survival. We found that loss of CHCHD4 protects tumour cells from respiratory chain inhibition at CI, while elevated CHCHD4 expression in tumour cells leads to significantly increased sensitivity to CI inhibition, in part through the production of mitochondrial reactive oxygen species (ROS). Conclusions: Our study highlights an important role for CHCHD4 in regulating tumour cell metabolism and reveals that CHCHD4 confers metabolic vulnerabilities to tumour cells through its control of the mitochondrial respiratory chain and CI biology.
... Tumor cells upregulate glucose metabolism and oxidative phosphorylation (OXPHOS) to support their enhanced anabolic demands [1,2]. Apart from glycolysis, glucose is also utilized by the pentose phosphate pathway, the hexosamine pathway, and the one-carbon metabolism pathway to generate building blocks and reducing power for the cell [1]. ...
Article
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Tumor cells utilize glucose to fuel their anabolic needs, including rapid proliferation. However, due to defective vasculature and increased glucose uptake, tumor cells must overcome glucose deprivation. Accordingly, tumor cells depend on cellular pathways promoting survival under such conditions. Targeting these survival mechanisms can thus serve as a new therapeutic strategy in oncology. As such, we sought to identify small-molecule inhibitors which sensitize tumor cells to glucose starvation by high-throughput drug screening in vitro. Specifically, we searched for inhibitors that selectively killed tumor cells growing in glucose-free but not in normal medium. This phenotypic drug screen of 7000 agents with MCF7 cells led to the identification of 67 potential candidates, 31 of which were validated individually. Among the identified compounds, we found a high number of compounds known to target mitochondria. The efficacies of two of the identified compounds, QNZ (EVP4593) and papaverine, were validated in four different tumor cell lines. We found that these agents inhibited the mTOR(Mechamistic\Mammilian Target of Rapamycin) pathway in tumor cells growing under glucose starvation, but not under normal conditions. The results were validated and confirmed in vivo, with QNZ and papaverine exhibiting superior antitumor activity in a tumor xenograft model when combined with the VEGF inhibitor bevacizumab (avastin). Administering these drug combinations (i.e., avastin and papaverine, and avastin and QNZ) led to significant reductions in proliferation and mTOR activity of the aggressive DLD1 colon cell line in mice. Given our findings, we propose that compounds targeting metabolically challenged tumors, such as inhibitors of mitochondrial activity, be considered as a therapeutic strategy in cancer.
... Tumor cells upregulate glucose metabolism and oxidative phosphorylation (OXPHOS) to support their enhanced anabolic demands [1,2]. Apart from glycolysis, glucose is also utilized by the pentose phosphate pathway, the hexosamine pathway, and the one-carbon metabolism pathway to generate building blocks and reducing power for the cell [1]. ...
... S. cerevisiae yeasts are characterized by their high capability to ferment simple sugars into ethanol even in the presence of oxygen, known as Crabtree effect (Crabtree, 1928). Although, alcohol fermentation is energetically much less efficient than aerobic respiration, it provides with a selective advantage to these yeasts to outcompete other microorganisms: sugar resources are consumed faster and the ethanol produced during fermentation (Goddard, 2008), as well as higher levels of heat and CO 2 , can be harmful or less tolerated by their competitors (Piskur and Langkjaer, 2004;Piškur et al., 2006;Conant and Wolfe, 2007;Merico et al., 2007;Hagman et al., 2013;Williams et al., 2015). ...
Article
Grape must is a sugar‐rich habitat for a complex microbiota which is replaced by Saccharomyces cerevisiae strains during the first fermentation stages. Interest on yeast competitive interactions has recently been propelled due to the use of alternative yeasts in the wine industry to respond to new market demands. The main issue resides in the persistence of these yeasts due to the specific competitive activity of S. cerevisiae. To gather deeper knowledge of the molecular mechanisms involved, we performed a comparative transcriptomic analysis during fermentation carried out by a wine S. cerevisiae strain and a strain representative of the cryophilic S. kudriavzevii, which exhibits high genetic and physiological similarities to S. cerevisiae, but also differences of biotechnological interest. In this study, we report that transcriptomic response to the presence of a competitor is stronger in S. cerevisiae than in S. kudriavzevii. Our results demonstrate that a wine S. cerevisiae industrial strain accelerates nutrient uptake and utilization to outcompete the co‐inoculated yeast, and that this process requires cell‐to‐cell contact to occur. Finally, we propose that this competitive phenotype evolved recently, during the adaptation of S. cerevisiae to man‐manipulated fermentative environments, since a non‐wine S. cerevisiae strain, isolated from a North American oak, showed a remarkable low response to competition. This article is protected by copyright. All rights reserved.
... S. cerevisiae and Sz. pombe readily ferment sugars and produce ethanol in the presence of oxygen, a process known as Crabtree effect (Crabtree, 1928;Dashko et al., 2014;Snoek and Steensma, 2006), and are also promptly able to sustained anaerobic growth despite higher energetic costs (Dashko et al., 2014;Lai et al., 2006). Therefore, these yeast species are adapted to current oxygen atmospheric levels conditions (21%) and hypoxic environments, where oxygen concentrations are lower than atmospheric levels (Postmus et al., 2011a(Postmus et al., ). ...
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The evolution of mitochondrial genomes is essential for the adaptation of yeasts to the variation of environmental levels of oxygen. Although Saccharomyces cerevisiae mitochondrial DNA lacks all complex I genes, respiration is possible because alternative NADH dehydrogenases are encoded by NDE1 and NDI1 nuclear genes. The proposed whole genome duplication (WGD) in the yeast ancestor at 150-100 million years ago caused nuclear gene duplications and secondary losses, although its relation to the loss of complex I mitocondrial is unknown. Here we present phylogenomic supertrees and supermatrix tree of 46 mitochondrial genomes showing that the loss of complex I predates WGD and occurred independently in the S. cerevisiae group and the fission yeast Schizosaccharomyces pombe. We also show that the branching patterns do not differ dramatically in supertrees and supermatrix phylogenies. Our inferences indicated consistent relations between conserved mitochondrial chromosomal gene order (synteny) in closely related yeasts. Correlation of mitochondrial molecular clock estimates and atmospheric oxygen variation in the Phanerozoic suggests that the Saccharomyces lineage might have lost the complex I during hypoxic periods near Perminian-Triassic or Triassic-Jurassic mass extinction events, while the Schizosaccharomyces lineage possibly lost the complex I during hypoxic environment periods during Middle Cambrian until Lower Devonian. The loss of mitochondrial complex I during low oxygen might not affect yeast metabolism due to fermentative switch. The return to increased oxygen periods might have favored adaptations to aerobic metabolism. Additionally, we also showed that NDE1 and NDI1 phylogenies indicate evolutionary convergence in yeasts where mitochondrial complex I is absent.
... He cerevisiae. This repression of respiration by glucose was first described by Herbert Crabtree in 1928 and was therefore called the "Crabtree effect" (47). It was later shown that several other yeasts show a similar tendency toward fermentation and thus are also Crabtree positive (14,48). ...
Article
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The lag phase is arguably one of the prime characteristics of microbial growth. Longer lag phases result in lower competitive fitness in variable environments, and the duration of the lag phase is also important in many industrial processes where long lag phases lead to sluggish, less efficient fermentations. Despite the immense importance of the lag phase, surprisingly little is known about the exact molecular processes that determine its duration. Our study uses the molecular toolbox of S. cerevisiae combined with detailed growth experiments to reveal how the transition from fermentative to respirative metabolism is a key bottleneck for cells to overcome the lag phase. Together, our findings not only yield insight into the key molecular processes and genes that influence lag duration but also open routes to increase the efficiency of industrial fermentations and offer an experimental framework to study other types of lag behavior.
... Culturing tumor cells in glucose-free (galactose-containing) media forces them to utilize the respiratory chain and produce ATP via oxidative phosphorylation (34). Thus to evaluate the contribution of HIF-2α to respiration in the presence and absence of glucose, we measured basal OCR in 786O cells in the context of HIF-2α knockdown ( Figure 3E). ...
Article
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Dysregulated mitochondrial function is associated with the pathology of a wide range of diseases including renal disease and cancer. Thus, investigating regulators of mitochondrial function is of particular interest. Previous work has shown that the von Hippel-Lindau tumor suppressor protein (pVHL) regulates mitochondrial biogenesis and respiratory chain function. pVHL is best known as an E3-ubiquitin ligase for the α-subunit of the hypoxia inducible factor (HIF) family of dimeric transcription factors. In normoxia, pVHL recognizes and binds hydroxylated HIF-α (HIF-1α and HIF-2α), targeting it for ubiquitination and proteasomal degradation. In this way, HIF transcriptional activity is tightly controlled at the level of HIF-α protein stability. At least 80% of clear cell renal carcinomas exhibit inactivation of the VHL gene, which leads to HIF-α protein stabilization and constitutive HIF activation. Constitutive HIF activation in renal carcinoma drives tumor progression and metastasis. Reconstitution of wild-type VHL protein (pVHL) in pVHL-defective renal carcinoma cells not only suppresses HIF activation and tumor growth, but also enhances mitochondrial respiratory chain function via mechanisms that are not fully elucidated. Here, we show that pVHL regulates mitochondrial function when re-expressed in pVHL-defective 786O and RCC10 renal carcinoma cells distinct from its regulation of HIF-α. Expression of CHCHD4, a key component of the disulphide relay system (DRS) involved in mitochondrial protein import within the intermembrane space (IMS) was elevated by pVHL re-expression alongside enhanced expression of respiratory chain subunits of complex I (NDUFB10) and complex IV (mtCO-2 and COX IV). These changes correlated with increased oxygen consumption rate (OCR) and dynamic changes in glucose and glutamine metabolism. Knockdown of HIF-2α also led to increased OCR, and elevated expression of CHCHD4, NDUFB10, and COXIV in 786O cells. Expression of pVHL mutant proteins (R200W, N78S, D126N, and S183L) that constitutively stabilize HIF-α but differentially promote glycolytic metabolism, were also found to differentially promote the pVHL-mediated mitochondrial phenotype. Parallel changes in mitochondrial morphology and the mitochondrial network were observed. Our study reveals a new role for pVHL in regulating CHCHD4 and mitochondrial function in renal carcinoma cells.
... Our previous experiments showing that TCS is a mitochondrial uncoupler were performed in the absence of glucose. Glucose was omitted from those experiments because, in the presence of glucose, cells (both immortalized (Crabtree 1928;Ibsen 1961) and primary (Wang et al. 1976)) rely on glycolysis to generate ATP and, therefore, bypass mitochondrial oxidative phosphorylation (the "Crabtree effect"). Thus, in order to probe effects of mitochondrial toxicants on oxidative phosphorylation (Marroquin et al. 2007), cells must be forced to undergo oxidative phosphorylation; this effect is accomplished experimentally by omitting glucose, which is replaced by glutamine plus galactose ("galactose media"). ...
Article
The antimicrobial agent triclosan (TCS) is used in products such as toothpaste and surgical soaps and is readily absorbed into oral mucosa and human skin. These and many other tissues contain mast cells, which are involved in numerous physiologies and diseases. Mast cells release chemical mediators through a process termed degranulation, which is inhibited by TCS. Investigation into the underlying mechanisms led to the finding that TCS is a mitochondrial uncoupler at non-cytotoxic, low-micromolar doses in several cell types and live zebrafish. Our aim was to determine the mechanisms underlying TCS disruption of mitochondrial function and of mast cell signaling. We combined super-resolution (fluorescence photoactivation localization) microscopy and multiple fluorescence-based assays to detail triclosan's effects in living mast cells, fibroblasts, and primary human keratinocytes. TCS disrupts mitochondrial nanostructure, causing mitochondria to undergo fission and to form a toroidal, "donut" shape. TCS increases reactive oxygen species production, decreases mitochondrial membrane potential, and disrupts ER and mitochondrial Ca2+levels, processes that cause mitochondrial fission. TCS is 60 × more potent than the banned uncoupler 2,4-dinitrophenol. TCS inhibits mast cell degranulation by decreasing mitochondrial membrane potential, disrupting microtubule polymerization, and inhibiting mitochondrial translocation, which reduces Ca2+influx into the cell. Our findings provide mechanisms for both triclosan's inhibition of mast cell signaling and its universal disruption of mitochondria. These mechanisms provide partial explanations for triclosan's adverse effects on human reproduction, immunology, and development. This study is the first to utilize super-resolution microscopy in the field of toxicology.
... This 'aerobic glycolysis' phenomenon has been referred to as the' Warburg effect' (Warburg et al. 1927;Diaz-Ruiz et al. 2011;Liberti and Locasale 2016). Also, early efforts by Crabtree, a contemporary of Warburg, demonstrated that glucose inhibited tumor cell respiration by a process linked to diminished oxidative phosphorylation (Crabtree 1928(Crabtree , 1929. This phenomenon has come to be called the 'Crabtree effect' and is considered a short-term adaptation to glucose elevation (Diaz-Ruiz et al. 2011;Dell' Antone 2012;Hammad et al. 2016). ...
Article
Cancer cells exhibit unregulated growth, altered metabolism, enhanced metastatic potential and altered cell surface glycans. Fueledby oncometabolism and elevated uptake of glucose and glutamine, the hexosamine biosynthetic pathway (HBP) sustains glyco-sylation in the endomembrane system. In addition, the elevated pools of UDP-GlcNAc drives the O-GlcNAc modification of keytargets in the cytoplasm, nucleus and mitochondrion. These targets include transcription factors, kinases, key cytoplasmic enzymesof intermediary metabolism, and electron transport chain complexes. O-GlcNAcylation can thereby alter epigenetics, transcription,signaling, proteostasis, and bioenergetics, key ‘hallmarks of cancer’. In this review, we summarize accumulating evidence thatmany cancer hallmarks are linked to dysregulation of O-GlcNAc cycling on cancer-relevant targets. We argue that onconutrientand oncometabolite-fueled elevation increases HBP flux and triggers O-GlcNAcylation of key regulatory enzymes in glycolysis,Kreb’s cycle, pentose-phosphate pathway, and the HBP itself. The resulting rerouting of glucose metabolites leads to elevated O-GlcNAcylation of oncogenes and tumor suppressors further escalating elevation in HBP flux creating a ‘vicious cycle’.Downstream, elevated O-GlcNAcylation alters DNA repair and cellular stress pathways which influence oncogenesis. Theelevated steady-state levels of O-GlcNAcylated targets found in many cancers may also provide these cells with a selectiveadvantage for sustained growth, enhanced metastatic potential, and immune evasion in the tumor microenvironment.
... Warburg hypothesized that cancer cells have defective mitochondria and consequently require higher rates of glycolysis to sustain the energy demand of tumour growth [5]. Working with normal tissues subject to viral infections, Crabtree demonstrated that aerobic glycolysis is not unique to cancer cells and he postulated a repression of respiration by glycolysis [6], the Crabtree effect. Today it is well established that aerobic glycolysis is an ubiquitous phenotype of cells from all life kingdoms [7] and cancer cells as well [8,9]. ...
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The Pasteur effect dictates that oxygen induces respiration and represses fermentation. However, we have shown that oxygen stimulates mitochondrial formate production and excess formate production induces glycolysis in mammalian cells. Our observations suggest the hypothesis that increased respiration induces an increase, rather than a decrease, of fermentation, the reverse Pasteur effect. Using a mathematical model we show that, in the absence of mitochondrial formate production, we should always observe the Pasteur effect, a reduction in fermentation with increasing respiration. However, in cells with active mitochondrial formate production, the rate of fermentation first increases with increasing the rate of respiration, indicating a metabolic sweet spot at moderate oxygen availability that is within the range of tissue oxygen tensions. We provide experimental evidence for the manifestation of the reverse Pasteur effect at such oxygen tension.
... Interestingly, different morphological tumors, such as oral squamous cell carcinoma [89], lung [90], breast [91], pancreatic carcinomas [92], and hepatocarcinoma [93], show various alterations in carbohydrate metabolic pathways. In normal cells, a high glycolysis rate is linked to a reduction in OXPHOS, known as the Crabtree effect [94]. Unless tumor cells become hypoxic, they maintain high glycolysis and OXPHOS rates to meet the high energy demand of anabolic processes. ...
Article
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A comprehensive view of cell metabolism provides a new vision of cancer, conceptualized as tissue with cellular-altered metabolism and energetic dysfunction, which can shed light on pathophysiological mechanisms. Cancer is now considered a heterogeneous ecosystem, formed by tumor cells and the microenvironment, which is molecularly, phenotypically, and metabolically reprogrammable. A wealth of evidence confirms metabolic reprogramming activity as the minimum common denominator of cancer, grouping together a wide variety of aberrations that can affect any of the different metabolic pathways involved in cell physiology. This forms the basis for a new proposed classification of cancer according to the altered metabolic pathway(s) and degree of energy dysfunction. Enhanced understanding of the metabolic reprogramming pathways of fatty acids, amino acids, carbohydrates, hypoxia, and acidosis can bring about new therapeutic intervention possibilities from a metabolic perspective of cancer.
... Due to limited oxygen supply, this leads to high levels of lactate production. This phenomenon is known since the 1920s and named after his discoverer "Warburg" (Crabtree, 1928). Tumor suppressors and oncogenes are able to modulate the aerobic glycolysis of tumor cells and are thereby regulating tumor growth. ...
Article
Full-text available
Cardiovascular diseases have multifactorial causes. Classical cardiovascular risk factors, such as arterial hypertension, smoking, hyperlipidemia, and diabetes associate with the development of vascular stenoses and coronary heart disease. Further comorbidities and its impact on cardiovascular metabolism have gotten more attention recently. Thus, also cancer biology may affect the heart, apart from cardiotoxic side effects of chemotherapies. Cancer is a systemic disease which primarily leads to metabolic alterations within the tumor. An emerging number of preclinical and clinical studies focuses on the interaction between cancer and a maladaptive crosstalk to the heart. Cachexia and sarcopenia can have dramatic consequences for many organ functions, including cardiac wasting and heart failure. These complications significantly increase mortality and morbidity of heart failure and cancer patients. There are concurrent metabolic changes in fatty acid oxidation (FAO) and glucose utilization in heart failure as well as in cancer, involving central molecular regulators, such as PGC-1α. Further, specific inflammatory cytokines (IL-1β, IL-6, TNF-α, INF-β), non-inflammatory cytokines (myostatin, SerpinA3, Ataxin-10) and circulating metabolites (D2-HG) may mediate a direct and maladaptive crosstalk of both diseases. Additionally, cancer therapies, such as anthracyclines and angiogenesis inhibitors target common metabolic mechanisms in cardiomyocytes and malignant cells. This review focuses on cardiovascular, cancerous, and cancer therapy-associated alterations on the systemic and cardiac metabolic state.
... While aerobic glycolysis is a universal phenotype of tumour cells, it is now clearly established that tumour cells need not necessarily be defective in mitochondrial respiratory function (Fantin et al. 2006;Le et al. 2010;Schell et al. 2014;Senyilmaz and Teleman 2015). Following Warburg's observation, Crabtree proposed that glucose inhibits mitochondrial function in tumour cells (Crabtree 1928). Since then, studies carried out to understand Crabtree effect in tumours (Ibsen 1961;Guppy et al. 1993;Marin-Hernandez et al. 2006;Suchorolski et al. 2013) have revealed a plethora of different mechanisms. ...
Article
Tumour cells distinguish from normal cells by fermenting glucose to lactate in presence of sufficient oxygen and functional mitochondria (Warburg effect). Crabtree effect was invoked to explain the biochemical basis of Warburg effect by suggesting that excess glucose suppresses mitochondrial respiration. It is known that the Warburg effect and Crabtree effect are displayed by Saccharomyces cerevisiae, during growth on abundant glucose. Beyond this similarity, it was also demonstrated that expression of human pro-apoptotic proteins in S. cerevisiae such as Bax and p53 caused apoptosis. Here, we demonstrate that p53 expression in S. cerevisiae (Crabtree-positive yeast) causes increase in ROS levels and apoptosis when cells are growing on non-fermentable carbon sources but not on fermentable carbon sources, a feature similar to tumour cells. In contrast, in Kluyveromyces lactis (Crabtree-negative yeast) p53 causes increase in ROS levels and apoptosis regardless of the carbon source. Interestingly, the increased ROS levels and apoptosis are correlated to increased oxygen uptake in both S. cerevisiae and K. lactis. Based on these results, we suggest that at least in yeast, fermentation per se does not prevent the escape from apoptosis. Rather, the Crabtree effect plays a crucial role in determining whether the cells should undergo apoptosis or not.
... The use of Saccharomyces cerevisiae in the wine, brewing and baking industry is a mature technology [10], whereas opportunity remains for non-Saccharomyces yeast production and inclusion as seed cultures for wine fermentation. The unique metabolic characteristics of S. cerevisiae, notably the Crabtree effect, are exploited during application in winemaking [11,12], where a decrease in the biomass yield from ethanol production could result at (i) high growth rates under carbon limitation, i.e. the long-term Crabtree effect, or (ii) elevated residual sugar concentrations, the short-term Crabtree effect [13][14][15]. Blank et al. [16] concluded that the Crabtree effect is not absolute, but differs in intensity between different yeasts (including non-Saccharomyces yeast), which implies that sensitivity to glucose is strain and species-related, and where S. cerevisiae exhibits the strongest Crabtree response [17]. ...
Article
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Non-Saccharomyces wine yeasts are of increasing importance due to their influence on the organoleptic properties of wine and thus the factors influencing the biomass production of these yeasts, as starter cultures, are of commercial value. Therefore, the effects of growth rates on the biomass yield (Yx/s) and fermentation performance of non-Saccharomyces yeasts at bench and pilot scale were examined. The fermentative performance and (Yx/s) were optimised, in aerobic fed-batch cultivations, to produce commercial wine seed cultures of Lachancea thermotolerans Y1240, Issatchenkia orientalis Y1161 and Metschnikowia pulcherrima Y1337. Saccharomyces cerevisiae (Lalvin EC1118) was used as a benchmark. A Crabtree positive response was shown by L. thermotolerans in a molasses-based industrial medium, at growth rates exceeding 0.21 h−1 (µcrit), resulting in a Yx/s of 0.76 g/g at 0.21 h−1 (46% of µmax) in the aerobic bioreactor-grown fed-batch culture at bench scale. At pilot scale and 0.133 h−1 (36% of µmax), this yeast exhibited ethanol concentrations reaching 10.61 g/l, as a possible result of substrate gradients. Crabtree negative responses were observed for I. orientalis and M. pulcherrima resulting in Yx/s of 0.83 g/g and 0.68 g/g, respectively, below 32% of µmax. The Yx/s of M. pulcherrima, I. orientalis and L. thermotolerans was maximised at growth rates between 0.10 and 0.12 h−1 and the fermentative capacity of these yeasts was maximised at these lower growth rates.
... Saccharomyces cerevisiae and Sz. pombe readily ferment sugars and produce ethanol in the presence of oxygen, a process known as the Crabtree effect (Crabtree, 1928;Snoek and Steensma, 2006;Dashko et al., 2014), and are also promptly able to sustain anaerobic growth despite higher energetic costs (Lai et al., 2006;Dashko et al., 2014). Therefore, these yeast species are adapted to current oxygen atmospheric levels conditions (21%) and hypoxic environments, in which oxygen concentrations are lower than current atmospheric levels (Postmus et al., 2011a). ...
Article
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Evolution of mitochondrial genomes is essential for the adaptation of yeasts to changes in environmental oxygen levels. Although Saccharomyces cerevisiae mitochondrial DNA lacks all complex I genes, respiration is possible because alternative NADH dehydrogenases are encoded by NDE1 and NDI1 nuclear genes. The apparent whole genome duplication (WGD) in the yeast ancestor 100-150 million years ago caused nuclear gene duplications and secondary losses, although its relation to the loss of mitochondrial complex I is unknown. We produced phylogenomic supertrees and a supermatrix tree of 46 mitochondrial genomes, showing that the loss of complex I predates WGD and occurred independently in the S. cerevisiae group and the fission yeast Schizosaccharomyces pombe. The branching patterns did not differ substantially in supertrees and supermatrix phylogenies. We found consistent relations between conserved mitochondrial chromosomal gene order (synteny) in closely related yeasts. Correlation of mitochondrial molecular clock estimates and atmospheric oxygen variation in the Phanerozoic suggests that the Saccharomyces lineage might have lost complex I during hypoxic periods near Permian-Triassic or Triassic-Jurassic mass extinction events, while the Schizosaccharomyces lineage possibly lost complex I during hypoxic environment periods during the Middle Cambrian until the Lower Devonian. The loss of mitochondrial complex I, as a result of low oxygen levels, might not affect yeast metabolism due to a fermentative switch. The return to increased oxygen periods could have favored adaptations to aerobic metabolism. Additionally, we also show that NDE1 and NDI1 phylogenies indicate evolutionary convergence in yeasts in which mitochondrial complex I is absent.
... Shortly after the discovery of aerobic glycolysis in cancer cells, Herbert Crabtree provided the first evidence of glycolytic heterogeneity in cancer by demonstrating that glycolysis was not uniformly elevated in tumors, even within tumors of the same type (Crabtree, 1929). Further studies revealed that aerobic glycolysis was not restricted to tumor cells but was found in other various neoplastic and normal tissues (Murphy and Hawkins, 1925;Crabtree, 1928). Crabtree attributed this glycolytic heterogeneity to various genetic and environmental influences, but it was not until after the discovery of oncogenes that the genetic foundation of cancer metabolism was uncovered. ...
Article
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Tumors are dynamic metabolic systems which highly augmented metabolic fluxes and nutrient needs to support cellular proliferation and physiological function. For many years, a central hallmark of tumor metabolism has emphasized a uniformly elevated aerobic glycolysis as a critical feature of tumorigenecity. This led to extensive efforts of targeting glycolysis in human cancers. However, clinical attempts to target glycolysis and glucose metabolism have proven to be challenging. Recent advancements revealing a high degree of metabolic heterogeneity and plasticity embedded among various human cancers may paint a new picture of metabolic targeting for cancer therapies with a renewed interest in glucose metabolism. In this review, we will discuss diverse oncogenic and molecular alterations that drive distinct and heterogeneous glucose metabolism in cancers. We will also discuss a new perspective on how aberrantly altered glycolysis in response to oncogenic signaling is further influenced and remodeled by dynamic metabolic interaction with surrounding tumor-associated stromal cells.
... At the same time as Otto Warburg, Herbert G. Crabtree studied the heterogeneity of glycolysis in tumors, describing that the magnitude and relationships between respiratory and glycolytic processes were a common feature of uncontrolled proliferation and not specific to malignant tissues (12). He observed considerable variability between respiratory and glycolytic metabolism among different tumors (13). ...
Article
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For a long time, pioneers in the field of cancer cell metabolism, such as Otto Warburg, have focused on the idea that tumor cells maintain high glycolytic rates even with adequate oxygen supply, in what is known as aerobic glycolysis or the Warburg effect. Recent studies have reported a more complex situation, where the tumor ecosystem plays a more critical role in cancer progression. Cancer cells display extraordinary plasticity in adapting to changes in their tumor microenvironment, developing strategies to survive and proliferate. The proliferation of cancer cells needs a high rate of energy and metabolic substrates for biosynthesis of biomolecules. These requirements are met by the metabolic reprogramming of cancer cells and others present in the tumor microenvironment, which is essential for tumor survival and spread. Metabolic reprogramming involves a complex interplay between oncogenes, tumor suppressors, growth factors and local factors in the tumor microenvironment. These factors can induce overexpression and increased activity of glycolytic isoenzymes and proteins in stromal and cancer cells which are different from those expressed in normal cells. The fructose-6-phosphate/fructose-1,6-bisphosphate cycle, catalyzed by 6-phosphofructo-1-kinase/fructose 1,6-bisphosphatase (PFK1/FBPase1) isoenzymes, plays a key role in controlling glycolytic rates. PFK1/FBpase1 activities are allosterically regulated by fructose-2,6-bisphosphate, the product of the enzymatic activity of the dual kinase/phosphatase family of enzymes: 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase (PFKFB1-4) and TP53-induced glycolysis and apoptosis regulator (TIGAR), which show increased expression in a significant number of tumor types. In this review, the function of these isoenzymes in the regulation of metabolism, as well as the regulatory factors modulating their expression and activity in the tumor ecosystem are discussed. Targeting these isoenzymes, either directly or by inhibiting their activating factors, could be a promising approach for treating cancers.
... Cela l'amena à considérer que la respiration cellulaire, au travers du processus de phosphorylation oxydative (OXPHO), était altérée (Warburg, 1931(Warburg, , 1956Warburg et al., 1927), ce qui fût contredit par les travaux de Sydney Weinhouse qui montra que l'OXPHO avait bien lieu dans la cellule tumorale (Weinhouse, 1951(Weinhouse, , 1955(Weinhouse, , 1972. La cellule tumorale maintient donc à la fois de haut taux de glycolyse mais aussi d'OXPHO afin de répondre aux importants besoins énergétiques (Crabtree, 1928). ...
Thesis
Le cancer du sein est le cancer le plus fréquent et le plus meurtrier chez la femme. L’indice de masse corporelle (IMC), l’imprégnation œstrogènique et la densité mammaire (DM), facteurs connus pour influencer l’adiposité mammaire représentent également des facteurs de risque. Notre objectif est d’étudier l’influence de l’adiposité dans les mécanismes d’initiation et de progression tumorale mammaire. Nous avons comparé les effets des sécrétions des adipocytes différenciés à partir d’ASCs mammaires normaux ou isolés à partir de tissu adipeux mammaires adjacent à la tumeur. Les deux types de milieux conditionnés se sont montrés équivalents dans leurs effets sur l’augmentation de l’expression de CD36 dans les cellules tumorales, la captation d’AGs ainsi que la prolifération. En revanche les milieux conditionnés d’adipocytes normaux ont montré un pouvoir chemoattractant plus important sur la migration et l’invasion des cellules tumorales agressives. A l’inverse les milieux conditionnés d’adipocytes différenciés à partir d’ASC péritumoraux ont montré un effet supérieur sur la migration des cellules mammaires normales. Ces effets observés sont dépendants du phénotype des cellules tumorales mammaires mais indépendamment du niveau d’adiposité. Ces données sont particulièrement intéressantes dans les stratégies de reconstruction mammaire après tumorectomie ou mastectomie.
... Cependant, cette voie peut aussiêtre utilisée par la cellule en présence de dioxygène. Nous pouvons par exemple citer l'effet Crabtree [22] : la levure Saccharomyces cerevisiae produit de l'éthanol lorsqu'il y a beaucoup de glucose dans le milieu, même en présence de dioxygène. On peut aussi citer l'effet Warburg [23] du nom du Docteur Otto Warburg qui a découvert dans les années 1930 que les cellules cancéreuses produisaient leurénergie en utilisant la glycolyse et la production de lactate plutôt qu'en utilisant la glycolyse et le cycle de Krebs, même en présence de dioxygène. ...
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L’objectif de cette thèse est d’étudier comment la cellule mammifère adapte son métabolisme aux étapes du cycle cellulaire. Le cycle cellulaire est l’ensemble des étapes menant une cellule à se diviser. Le rôle du métabolisme est de fournir à la cellule les éléments et l’énergie dont elle a besoin pour fonctionner. En particulier, à chaque étape du cycle cellulaire, la cellule a besoin de différents éléments pour pouvoir, à terme, se diviser correctement. Il est donc crucial pour la cellule de coordonner le métabolisme et le cycle cellulaire et en particulier de contrôler ce que le métabolisme produit au cours du cycle cellulaire. Pour mieux comprendre ce lien entre ces deux processus, nous avons étudié comment un modèle mathématique du métabolisme répondait à différentes variations imposées par le cycle cellulaire et nous avons comparé ces réponses à la littérature. Satisfaits des résultats obtenus, nous avons alors construit un modèle hybride représentant l’évolution du métabolisme au cours du cycle cellulaire. Nous retrouvons dans ce modèle hybride les grandes variations connues des voies métaboliques au cours des phases du cycle cellulaire ainsi que des variations expérimentales des métabolites énergétiques et redox. Encouragés par ces résultats, nous avons finalement perturbé notre modèle hybride pour retrouver des tendances du métabolisme dues au cancer, un ensemble de maladies touchant à la fois le cycle cellulaire et le métabolisme.
... By the end of the 1920 s, Warburg's claims were already being severely criticized by other researchers, including the English biochemist Herbert G. Crabtree (1892Crabtree ( -1966, who tested Warburg's findings against a far more diverse sample of tissues. 11 While partly confirming Warburg's work, Crabtree also found high levels of metabolic heterogeneity in cancer tissues, including wide variation in the use of oxidation and glycolysis, even in single cell lineages. He also identified noncancerous tissues that, in the presence of oxygen, extensively used glycolysis in energy production; and, conversely, malignant tissues that in the same conditions showed profuse signs of oxidation. ...
Article
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One century ago (1920), Otto Warburg (1883–1970) discovered that in liquid cultures of unicellular green algae (Chlorella sp.) molecular oxygen (O2) exerts an inhibitory effect on photosynthesis. Decades later, O2 dependent suppression of photosynthetic carbon dioxide (CO2) assimilation (the “green” Warbur geffect) was confirmed on the leaves of seed plants. Here, we summarize the history of this discovery and elucidate the consequences of the photorespiratory pathway in land plants with reference to unpublished CO2 exchange data measured on the leaves of sunflower (Helianthus annuus) plants. In addition, we discuss the inefficiency of the key enzyme Rubisco and analyze data concerning the productivity of C3 vs. C4 crop species (sunflower vs. maize, Zea mays). Warburg’s discovery inaugurated a research agenda in the biochemistry of photosynthetic CO2 assimilation that continues to the present. In addition, we briefly discuss Warburg’s model of metabolic processes in cancer, net primary production (global photosynthesis) with respect to climate change, trees and other land plants as CO2 removers, and potential climate mitigators in the Anthropocene.
... Especially in in vitro studies, the susceptibility of different cells lines to acute toxic effects of PAs was low (Field et al., 2015), which further complicates those kind of studies. This could be due to the fact that some cell lines switch their metabolism according to the so-called Crabtree effect (Crabtree, 1928). This effect describes that in presence of low-glucose concentrations cells in culture derive all their energy from anaerobic glycolysis rather than via mitochondrial oxidative phosphorylation (OXPHOS) despite of aerobic conditions. ...
Article
Ethnopharmacological relevance: Pyrrolizidine alkaloids (PAs) are secondary plant ingredients formed in many plant species to protect against predators. PAs are generally considered acutely hepatotoxic, genotoxic and carcinogenic. Up to now, only few in vitro and in vivo investigations were performed to evaluate their relative toxic potential. Aim of the study: The aim was to develop an in vitro screening method of their cytotoxicity. Materials and methods: Human and rodent hepatocyte cell lines (HepG2 and H-4-II-E) were used to assess cytotoxicity of the PA lasiocarpine. At concentrations of 25µM up to even 2400µM, no toxic effects in neither cell line was observed with standard cell culture media. Therefore, different approaches were investigated to enhance the susceptibility of cells to PA toxicity (using high-glucose or galactose-based media, induction of toxifying cytochromes, inhibition of metabolic carboxylesterase, and inhibition of glutathione-mediated detoxification). Results: Galactose-based culture medium (11.1mM) increased cell susceptibility in both cell-lines. Cytochrome P450-induction by rifampicin showed no effect. Inhibition of carboxylesterase-mediated PA detoxification by specific carboxylesterase 2 inhibitor loperamide (2.5µM) enhanced lasiocarpine toxicity, whereas the unspecific carboxylesterase inhibitor bis(4-nitrophenyl)phosphate (BNPP, 100µM)) had a weaker effect. Finally, the inhibition of glutathione-mediated detoxification by buthionine sulphoximine (BSO, 100µM) strongly enhanced lasiocarpine toxicity in H-4-II-E cells in low and medium, but not in high concentrations. Conclusions: If no toxicity is observed under standard conditions, susceptibility enhancement by using galactose-based media, loperamide, and BSO may be useful to assess relative acute cytotoxicity of PAs in different cell lines.
... This 'aerobic glycolysis' phenomenon has been referred to as the' Warburg effect' (Warburg et al. 1927;Diaz-Ruiz et al. 2011;Liberti and Locasale 2016). Also, early efforts by Crabtree, a contemporary of Warburg, demonstrated that glucose inhibited tumor cell respiration by a process linked to diminished oxidative phosphorylation (Crabtree 1928(Crabtree , 1929. This phenomenon has come to be called the 'Crabtree effect' and is considered a short-term adaptation to glucose elevation (Diaz-Ruiz et al. 2011;Dell' Antone 2012;Hammad et al. 2016). ...
Article
Full-text available
Cancer cells exhibit unregulated growth, altered metabolism, enhanced metastatic potential and altered cell surface glycans. Fueledby oncometabolism and elevated uptake of glucose and glutamine, the hexosamine biosynthetic pathway (HBP) sustains glyco-sylation in the endomembrane system. In addition, the elevated pools of UDP-GlcNAc drives the O-GlcNAc modification of keytargets in the cytoplasm, nucleus and mitochondrion. These targets include transcription factors, kinases, key cytoplasmic enzymesof intermediary metabolism, and electron transport chain complexes. O-GlcNAcylation can thereby alter epigenetics, transcription,signaling, proteostasis, and bioenergetics, key ‘hallmarks of cancer’. In this review, we summarize accumulating evidence thatmany cancer hallmarks are linked to dysregulation of O-GlcNAc cycling on cancer-relevant targets. We argue that onconutrientand oncometabolite-fueled elevation increases HBP flux and triggers O-GlcNAcylation of key regulatory enzymes in glycolysis,Kreb’s cycle, pentose-phosphate pathway, and the HBP itself. The resulting rerouting of glucose metabolites leads to elevated O-GlcNAcylation of oncogenes and tumor suppressors further escalating elevation in HBP flux creating a ‘vicious cycle’.Downstream, elevated O-GlcNAcylation alters DNA repair and cellular stress pathways which influence oncogenesis. Theelevated steady-state levels of O-GlcNAcylated targets found in many cancers may also provide these cells with a selectiveadvantage for sustained growth, enhanced metastatic potential, and immune evasion in the tumor microenvironment
Chapter
Microbial culture collections (including yeast cultures) focus at collecting, maintaining and distributing microbial strains amongst microbiologists, brewers and distillers. They are means of preserving microbial diversity. The importance of selecting optimal yeast strains for research and/or industrial applications is often underestimated. Yeast cultures stored in a yeast collection are usually (but not always) purified cultures. Today, it is possible for brewers, both home brewers and professionals, to obtain yeast strains from culture collections and have then been shipped worldwide. Prior to yeast propagation, it is imperative that no change in the character of the yeast strain occurs. Today, many breweries store their strains (or contract store them) at −70 °C. The yeast propagation process is not fully understood. Brewer’s yeast cultures do not live forever and must be replaced with fresh yeast on a regular basis. Yeast propagation was pioneered with lager strains in the late nineteenth century. However, the value of regular ale strain propagation is still questioned. With the advent of high-gravity wort fermentation, its use in ale propagation procedures (as well as lager) has become an accepted brewing procedure.
Article
The Saccharomyces cerevisiae and Candida albicans yeasts have evolved to differentially use glucose for fermentation versus respiration. S. cerevisiae is Crabtree positive, where glucose represses respiration and promotes fermentation, while the opportunistic fungal pathogen C. albicans is Crabtree negative and does not repress respiration with glucose. We have previously shown that glucose control in S. cerevisiae involves the antioxidant enzyme Cu/Zn superoxide dismutase (SOD1), where H2O2 generated by SOD1 stabilizes the casein kinase YCK1 for glucose sensing. We now demonstrate that C. albicans SODs also participate in glucose regulation. C. albicans expresses two cytosolic SODs, Cu/Zn SOD1 and Mn containing SOD3, and both complemented a S. cerevisiae sod1Δ mutant in stabilizing YCK1. Moreover, in C. albicans cells, both SODs functioned to repress glucose transporter genes in response to glucose. However, the action of SODs in glucose control has diverged in the two yeasts. In S. cerevisiae, SOD1 specifically functions in the glucose sensing pathway involving YCK1 and the RGT1 repressor, but the analogous YCK/RGT1 pathway in C. albicans shows no control by SOD enzymes. Instead C. albicans SODs work in the glucose repression pathway involving the MIG1 transcriptional repressor. In C. albicans, the SODs repress glucose uptake, while in S. cerevisiae, SOD1 activates glucose uptake, in accordance with the divergent modes for glucose utilization in these two distantly related yeasts.
Chapter
The overall process between brewing fermentations is collectively described as yeast management (this process does not apply to distilling because the yeast culture is normally only used once). Brewing yeast management includes strain storage (in a culture collection), propagation, cropping (also discussed in Chap. 13), culture storage and acid washing, and this leads to wort fermentation itself. This critical latter procedure is usually not regarded as yeast management and is discussed in Chaps. 6, 7, 13, 14 and 15. Distiller’s yeast can be purchased from manufacturers of baking and distilling yeasts. Today there are a number of specialized strains available depending on the particular fermentation and organoleptic profile desired in the fermented wort. Manufacturers of yeast for bakeries and distilleries aim for minimal alcohol production during the production process.
Article
The Crabtree effect in the yeast, Saccharomyces cerevisiae, has been extensively studied, but only few studies have analyzed the dynamic conditions across the critical specific growth rate where the Crabtree effect sets in. Here, we carried out a multi-omics analysis of S. cerevisiae undergoing a specific growth rate transition from 0.2 h-1 to 0.35 h-1. The extracellular metabolome, the transcriptome and the proteome were analyzed in an 8-hour transition period after the specific growth rate shifted from 0.2 h-1 to 0.35 h-1. The changing trends of both the transcriptome and proteome were analyzed using principal component analysis, which showed that the transcriptome clustered together after 60 min, while the proteome reached steady-state much later. Focusing on central carbon metabolism, we analyzed both the changes in the transcriptome and proteome, and observed an interesting changing pattern in the tricarboxylic acid (TCA) pathway, which indicates an important role for citric acid shuttling across the mitochondrial membrane for α-ketoglutarate accumulation during the transition from respiratory to respiro-fermentative metabolism. This was supported by a change in the oxaloacetate and malate shuttle. Together, our findings shed new light into the onset of the Crabtree effect in S. cerevisiae.
Article
At genome scale, it is not yet possible to devise detailed kinetic models for metabolism because data on the in vivo biochemistry are too sparse. Predictive large-scale models for metabolism most commonly use the constraint-based framework, in which network structures constrain possible metabolic phenotypes at steady state. However, these models commonly leave many possibilities open, making them less predictive than desired. With increasingly available -omics data, it is appealing to increase the predictive power of constraint-based models (CBMs) through data integration. Many corresponding methods have been developed, but data integration is still a challenge and existing methods perform less well than expected. Here, we review main approaches for the integration of different types of -omics data into CBMs focussing on the methods' assumptions and limitations. We argue that key assumptions - often derived from single-enzyme kinetics - do not generally apply in the context of networks, thereby explaining current limitations. Emerging methods bridging CBMs and biochemical kinetics may allow for -omics data integration in a common framework to provide more accurate predictions.
Thesis
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Significance The dominant view in both molecular and evolutionary biology is that genotype controls the adaptation to new environments. We propose an alternate hypothesis, in which the phenotype and genotype both play important roles in metabolic adaptation in the lifetime of the organism and in the evolutionary selection of adaptive metabolic traits. When studying the Crabtree effect in yeast, we found that homeostatic mechanisms in the starting phenotype, primarily the glycogen/trehalose shunt, allow adaptation to high glucose. Subsequent gene expression, rather than creating a new phenotype, optimizes the initial adaptation by expression of new homeostatic mechanisms. Metabolic homeostatic mechanisms, by allowing increased phenotypic plasticity, could also have played an important role in guiding the evolution of the Crabtree phenotype.
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