Role In Glycolysis Research Articles

Abstract 3487: Bioenergetic profiling of cancer cell lines: Quantifying the impact of glycolysis on cell proliferation

Abstract Fast proliferating cells require tight regulation to achieve a balance between the use of nutrients for ATP production (through glycolysis and oxidative phosphorylation) and the use of intermediate metabolites to sustain the increased biosynthetic activity. Cancer cells, but also high proliferative non-transformed cells exhibit high glycolytic activity during rapid proliferation even in the presence of normal oxygen concentrations in culture. However, despite the high glycolytic activity, the role of glycolysis is not necessary as a major contributor of ATP but to allow nutrient assimilation into biosynthetic precursors. Using Agilent Seahorse extracellular flux analysis, we have developed a cell-based assay which allows simultaneous measurement of the two-main cellular metabolic pathways to calculate the total rate of cellular ATP production as well as the fractional contribution from each pathway. The assay allows for real time changes in total ATP production rate to be quantified, and also the relative source of that ATP after exposure to drugs or changes in extracellular fuel supply. When we applied this new assay to a panel of 20 cancer and highly proliferative cell lines, we found that even in cell lines considered highly glycolytic, ATP production from glycolysis never represents more than 65% of total energy production and between 30-50% for most of the cell lines analyzed. The correlation between glycolytic ATP contribution to total ATP production and other cell phenotypes such as proliferation rate and motility was also analyzed. The use of this assay will allow for improved characterization of the bioenergetic profile of cancer cell variants, discrimination between normal and cancer cell types, and allow researchers to better understand the role of aerobic glycolysis in cell proliferation. Citation Format: Natalia Romero, Pamela M. Swain, Yoonseok Kam, George Rogers, Brian P. Dranka. Bioenergetic profiling of cancer cell lines: Quantifying the impact of glycolysis on cell proliferation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3487.

Abstract 1906: PFKFB4, much more than just a glycolytic gene

Abstract Glioblastoma is one of the most aggressive primary brain tumors in adults, with a dismal median overall survival of only 14 months after diagnosis. Glioblastoma stem-like cells (GSCs) are particularly resistant to current therapies, capable of self-renewal and tumour initiation and are hence thought to be major contributors to patient relapse. A kinome and phosphatome wide screen revealed glycolysis gene 6-Phosphofructo-2-Kinase/Fructose-2,6-Biphosphatase 4 (PFKFB4) as an important candidate gene for GSC survival. Notably, silencing PFKFB4 in an orthotopic xenograft mouse model of glioblastoma completely rid the mice of the tumor. Here we show a brand new function of PFKFB4, independent of its role in glycolysis - namely in the regulation of HIF1α, which is upregulated in GSCs. Gene expression profiling revealed a downregulation in HIF1α target genes in PFKFB4-silenced GSCs, and HIF1α protein levels are also dramatically reduced upon silencing. Mass spectrometric analysis of immunoprecipitated PFKFB4 protein revealed a novel interaction partner, F-box only protein 28 (FBXO28), an E3 ubiqutin ligase. Co-immunoprecipation assays show that FBXO28 forms an SCF multi-protein ubiquitin ligase complex with CUL1 and SKP1. Ubiquitylation studies of HIF1α show that PFKFB4 stabilizes this crucial protein in GSCs by preventing its targeting by FBXO28 for proteasomal degradation. These new findings, coupled with its cancer specific expression in a variety of tumor entities, makes PFKFB4 a compelling target. Citation Format: Emma L. Phillips, Frederic Bethke, Jörg Balss, Stefan Pusch, Stefan Christen, Martina Schnölzer, Antje Habel, David Capper, Andreas Von Deimling, Sarah-Maria Fendt, Peter Lichter, Violaine Goidts. PFKFB4, much more than just a glycolytic gene [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1906.

Abstract 5142: Elevated glycolysis in pre-malignant ovarian cancer

Abstract Ovarian cancer is the fifth leading cause of cancer death in women and the most lethal gynecologic malignancy. High-grade serous ovarian carcinoma (HGSC) originates mainly from the fallopian tube epithelium, and is characterized by TP53 mutation identified in all HGSCs as well as the fallopian tubal precursor of serous tubal intraepithelial carcinomas (STICs). The loss of a functional TP53 is an early event in the malignant transformation of fallopian tube epithelium. We have established 4 primary cell cultures of normal fallopian tube epithelial (FTE) cells, and further generated immortalized FTE cells using SV40 large plus small T antigens (FTE-TAg) to disrupt TP53 function. This model mimics the primary lesions of ovarian cancer and is suitable to identify biomarkers and molecular targets of ovarian cancer. Therefore, we compared the secretomes of primary FTE cells with that of their parental isogenic pairs FTE-TAg cells using mass spectrometry analysis. We identified 813 proteins, 228 of which were differentially expressed. Ingenuity Pathway Analysis (IPA) core analysis revealed glycolysis as a major canonical pathway. Overexpression of key enzymes of glycolytic pathway was confirmed by IHC in human STIC lesions. Molecular mechanisms of glycolysis regulation in premalignant lesion of ovarian cancer were determined. Role of glycolysis in the establishment of premalignant ovarian cancer microenvironment (PME) was characterized. Prevention approaches targeting glycolysis were tested in transgenic animal model of ovarian cancer. Citation Format: Anna E. Lokshin, Mounia Alaoui El Azher, Liudmila Velikokhatnaya, Denise Prosser. Elevated glycolysis in pre-malignant ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5142.

Organic Peroxide-Sensing Repressor OhrR Regulates Organic Hydroperoxide Stress Resistance and Avermectin Production in Streptomyces avermitilis.

The bacterium Streptomyces avermitilis is an industrial-scale producer of avermectins, which are important anthelmintic agents widely used in agriculture, veterinary medicine, and human medicine. During the avermectin fermentation process, S. avermitilis is exposed to organic peroxides generated by aerobic respiration. We investigated the role of MarR-family transcriptional regulator OhrR in oxidative stress response and avermectin production in S. avermitilis. The S. avermitilis genome encodes two organic hydroperoxide resistance proteins: OhrB1 and OhrB2. OhrB2 is the major resistance protein in organic peroxide stress responses. In the absence of organic peroxide, the reduced form of OhrR represses the expression of ohrB2 gene by binding to the OhrR box in the promoter region. In the presence of organic peroxide, the oxidized form of OhrR dissociates from the OhrR box and the expression of ohrB2 is increased by derepression. OhrR also acts as a repressor to regulate its own expression. An ohrR-deletion mutant (termed DohrR) displayed enhanced avermectin production. Our findings demonstrate that OhrR in S. avermitilis represses avermectin production by regulating the expression of pathway-specific regulatory gene aveR. OhrR also plays a regulatory role in glycolysis and the pentose phosphate (PP) pathway by negatively controlling the expression of pykA2 and ctaB/tkt2-tal2-zwf2-opcA2-pgl.

Cardioprotection by nicotinamide mononucleotide (NMN): Involvement of glycolysis and acidic pH

Stimulation of the cytosolic NAD+ dependent deacetylase SIRT1 is cardioprotective against ischemia-reperfusion (IR) injury. NAD+ precursors including nicotinamide mononucleotide (NMN) are thought to induce cardioprotection via SIRT1. Herein, while NMN protected perfused hearts against IR (functional recovery: NMN 42 ± 7% vs. vehicle 11 ± 3%), this protection was insensitive to the SIRT1 inhibitor splitomicin (recovery 47 ± 8%). Although NMN-induced cardioprotection was absent in Sirt3−/− hearts (recovery 9 ± 5%), this was likely due to enhanced baseline injury in Sirt3−/− (recovery 6 ± 2%), since similar injury levels in WT hearts also blunted the protective efficacy of NMN. Considering alternative cardiac effects of NMN, and the requirement of glycolysis for NAD+, we hypothesized NMN may confer protection in part via direct stimulation of cardiac glycolysis. In primary cardiomyocytes, NMN induced cytosolic and extracellular acidification and elevated lactate. In addition, [U-13C]glucose tracing in intact hearts revealed that NMN stimulated glycolytic flux. Consistent with a role for glycolysis in NMN-induced protection, hearts perfused without glucose (palmitate as fuel source), or hearts perfused with galactose (no ATP from glycolysis) exhibited no benefit from NMN (recovery 11 ± 4% and 15 ± 2% respectively). Acidosis during early reperfusion is known to be cardioprotective (i.e., acid post-conditioning), and we also found that NMN was cardioprotective when delivered acutely at reperfusion (recovery 39 ± 8%). This effect of NMN was not additive with acidosis, suggesting overlapping mechanisms. We conclude that the acute cardioprotective benefits of NMN are mediated in part via glycolytic stimulation, with the downstream protective mechanism involving enhanced ATP synthesis during ischemia and/or enhanced acidosis during reperfusion.

Posttranslational arginylation enzyme Ate1 is a mitochondrial‐derived master regulator that coordinates glycolysis and respiration in the Warburg effect

In the Warburg effect observed in vast majority of cancer cells, glycolysis is preferred over mitochondrial respiration. However, the role of mitochondria and its relationship with glycolysis in cancer metabolism is poorly understood. Arginyltransferase 1(Ate1) is an evolutionarily conserved enzyme that exist in most eukaryotes and a large subset of bacteria. In eukaryotes, this enzyme mediates arginylation, the posttranslational addition of one extra arginine to a protein. Recently, Ate1 was identified to be down‐regulated in many types of cancer but the significance of such observation remained unclear. Here, by examining classic glycolytic markers such glucose intake rate, sensitivity to glucose starvation, lactate generation, and the effects of glycolysis inhibitors including 2‐DG and 2‐FDG, we found that a deletion of Ate1 gene is sufficient to causes the Warburg effect on the cell level. This effect was reproduced by shRNA‐mediated knockdown of Ate1 and can be reversed by the expression of a recombinant Ate1 in the KO cells. In a screening of typical players involved in glycolysis, we found that the deletion of Ate1 increases of the protein level of hypoxia‐inducible factor 1a (HIF1a), a protein with known role in glycolysis. We found that the knockdown of HIF1a in Ate1‐KO cells was sufficient to reverse the glycolytic phenoytype in these cells, suggesting Ate1 regulates glycolysis through HIF1a. Furthermore, we found that Ate1 regulates the protein level of HIF1a through both conventional and unconventional pathways. In particularly, HIF1a appears to be a previous unknown substrate of Ate1‐mediated arginylation, which promotes the degradation of HIF1a through the N‐end rule. In addition, the deletion of Ate1 generate prominent effects on the morphology and functions of mitochondria, with significant defect on the assembly of mitochondrial complex II and a consequential accumulation of succinate, which is expected to stabilize the HIF1a protein by an inhibition of the PHD proteins. Finally, we found that eukaryotic Ate1 has significant homology to its counterpart in alpha‐proteobacteria, the ancestor of mitochondria. Also, although the majority of Ate1 is located in the cytosol, a detectable portion of Ate1 is located inside mitochondria. These evidence suggest that the Ate1 enzyme was derived from a gene transfer during the domestication of mitochondria, which further explains the previous unknown role of Ate1 as a master regulator of the balance between glycolysis and mitochondrial function.In summary, our study discovered a novel regulator of cell metabolism with a evolution root concomitant with mitochondria and our data suggest this regulator coordinates the balance between glycolysis and mitochondrial respiration in the cancer Warburg effect. Our data also reveal the existence of a non‐canonical degradation pathway of HIF1a.Support or Funding InformationNIGMS R01 GM107333This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Deregulation of Hexokinase II Is Associated with Glycolysis, Autophagy, and the Epithelial-Mesenchymal Transition in Tongue Squamous Cell Carcinoma under Hypoxia.

The glycolytic enzyme Hexokinase (HKII) participates in tumor glycolysis and the progression of various cancers, but its clinicopathological effect on the progression of tongue squamous cell carcinoma (TSCC) and its role in glycolysis, autophagy, and the epithelial-mesenchymal transition of TSCC in a hypoxic microenvironment remain unknown. Our results showed that HKII expression was dramatically increased in TSCC tissues and that its upregulation was significantly associated with the presence of pathological differentiation, lymph node metastasis, and clinical stage. The level of autophagy-specific protein LC3, EMT-related proteins, and the migration and invasion capabilities of TSCC cells all increased under hypoxia. Moreover, hypoxia increased the glucose consumption and lactate production of TSCC cells, and we demonstrated that the expression of the glycolytic key gene HKII was significantly higher than in that of the control group. Notably, the downregulation of HKII resulted in a significant decrease of TSCC cell glucose consumption lactate production and autophagic activity during hypoxia. HKII knockdown blocked the migratory and invasive capacity of TSCC cells and we specifically determined that the EMT ability decreased. Therefore, our findings revealed that the upregulation of HKII enhanced glycolysis and increased autophagy and the epithelial-mesenchymal transition of tongue squamous cell carcinoma under hypoxia.

PKM2 in carcinogenesis and oncotherapy.

Tumor cell metabolism is characterized by abundant glucose consumption and aerobic glycolysis. And pyruvate kinase M2 (PKM2) plays a decisive role in glycolysis, significantly contributing to the Warburg effect, tumor growth, angiogenesis, cell division, metastasis and apoptosis. To date, researchers have unraveled the potential of pyruvate kinase M2 as an antitumor target, which suggests a new orientation for oncotherapy. Herein, we focus on the role of pyruvate kinase M2 in tumor cell development and its function as a potential new therapeutic target for tumor treatment. Besides, research actuality on pyruvate kinase M2-dependent glycometabolism and signaling pathway in tumors is also summarized, providing valuable suggestions for further study in this field.

Glucose 6-phosphate isomerase (Pgi) is required for extracellular polysaccharide biosynthesis, DSF signals production and full virulence of Xanthomonas oryzae pv. oryzicola in rice

Xanthomonas oryzae pv. oryzicola (Xoc), the causal agent of bacterial leaf streak (BLS), recruits five carbohydrate catabolic pathways (glycolysis, ED, PPP, gluconeogenesis and TCA cycle) to acquire nutrients from host rice for parasitism and pathopoiesis. Glucose 6-phosphate isomerase (Pgi), which reversibly converts glucose 6-phosphate to fructose 6-phosphate, plays an important role in glycolysis and gluconeogenesis. In this study, we found that Pgi was essential for the pathogenicity of Xoc in rice. The mutagenesis in pgi caused the pathogen unable to effectively utilize fructose, sucrose, mannose and pyruvate for growth, but did not affect bacterial growth when glucose or galactose used as the sole carbon source. The expression of hrpX and hrpG was repressed and the transcription of hrpE, hpa3 and hrcU were enhanced when pgi or clp (encoding cAMP-regulatory protein) was mutated. Intriguingly, the mutation in pgi resulted in the transcription alteration of key genes, rpfF, rpfC, rpfG and clp, in the quorum-sensing (QS) signaling pathway mediated by diffusible signal factor (DSF) signals and significantly reduced DSF signals production compared with the wild-type. Additionally, the pgi deletion not only impaired bacterial growth and virulence in rice, but also reduced bacterial extracellular polysaccharide (EPS) biosynthesis and cell motility. The lost properties mentioned above in RΔpgi were completely restored to the wild-type levels by the presence of pgi in trans. Taken together, these findings exhibited functional roles of Pgi coordinating with the hrp system and the QS system mediated by DSF signals in carbon metabolic pathways.

Stabilization of phosphofructokinase 1 platelet isoform by AKT promotes tumorigenesis

Phosphofructokinase 1 (PFK1) plays a critical role in glycolysis; however, its role and regulation in tumorigenesis are not well understood. Here, we demonstrate that PFK1 platelet isoform (PFKP) is the predominant PFK1 isoform in human glioblastoma cells and its expression correlates with total PFK activity. We show that PFKP is overexpressed in human glioblastoma specimens due to an increased stability, which is induced by AKT activation resulting from phosphatase and tensin homologue (PTEN) loss and EGFR-dependent PI3K activation. AKT binds to and phosphorylates PFKP at S386, and this phosphorylation inhibits the binding of TRIM21 E3 ligase to PFKP and the subsequent TRIM21-mediated polyubiquitylation and degradation of PFKP. PFKP S386 phosphorylation increases PFKP expression and promotes aerobic glycolysis, cell proliferation, and brain tumor growth. In addition, S386 phosphorylation in human glioblastoma specimens positively correlates with PFKP expression, AKT S473 phosphorylation, and poor prognosis. These findings underscore the potential role and regulation of PFKP in human glioblastoma development.

Reconstructed ancestral enzymes reveal that negative selection drove the evolution of substrate specificity in ADP-dependent kinases

One central goal in molecular evolution is to pinpoint the mechanisms and evolutionary forces that cause an enzyme to change its substrate specificity; however, these processes remain largely unexplored. Using the glycolytic ADP-dependent kinases of archaea, including the orders Thermococcales, Methanosarcinales, and Methanococcales, as a model and employing an approach involving paleoenzymology, evolutionary statistics, and protein structural analysis, we could track changes in substrate specificity during ADP-dependent kinase evolution along with the structural determinants of these changes. To do so, we studied five key resurrected ancestral enzymes as well as their extant counterparts. We found that a major shift in function from a bifunctional ancestor that could phosphorylate either glucose or fructose 6-phosphate (fructose-6-P) as a substrate to a fructose 6-P-specific enzyme was started by a single amino acid substitution resulting in negative selection with a ground-state mode against glucose and a subsequent 1,600-fold change in specificity of the ancestral protein. This change rendered the residual phosphorylation of glucose a promiscuous and physiologically irrelevant activity, highlighting how promiscuity may be an evolutionary vestige of ancestral enzyme activities, which have been eliminated over time. We also could reconstruct the evolutionary history of substrate utilization by using an evolutionary model of discrete binary characters, indicating that substrate uses can be discretely lost or acquired during enzyme evolution. These findings exemplify how negative selection and subtle enzyme changes can lead to major evolutionary shifts in function, which can subsequently generate important adaptive advantages, for example, in improving glycolytic efficiency in Thermococcales.

Hif-1\u03b1 Knockdown Reduces Glycolytic Metabolism and Induces Cell Death of Human Synovial Fibroblasts Under Normoxic Conditions

Increased glycolysis and HIF-1α activity are characteristics of cells under hypoxic or inflammatory conditions. Besides, in normal O2 environments, elevated rates of glycolysis support critical cellular mechanisms such as cell survival. The purpose of this study was to analyze the contribution of HIF-1α to the energy metabolism and survival of human synovial fibroblasts (SF) under normoxic conditions. HIF-1α was silenced using lentiviral vectors or small-interfering RNA (siRNA) duplexes. Expression analysis by qRT-PCR and western blot of known HIF-1α target genes in hypoxia demonstrated the presence of functional HIF-1α in normoxic SF and confirmed the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a HIF-1α target even in normoxia. HIF-1α silencing induced apoptotic cell death in cultured SF and, similarly, treatment with glycolytic, but not with OXPHOS inhibitors, induced SF death. Finally, in vivo HIF-1α targeting by siRNA showed a significant reduction in the viability of human SF engrafted into a murine air pouch. Our results demonstrate that SF are highly dependent on glycolytic metabolism and that HIF-1α plays a regulatory role in glycolysis even under aerobic conditions. Local targeting of HIF-1α provides a feasible strategy to reduce SF hyperplasia in chronic arthritic diseases.

18F-fluorodeoxyglucose uptake predicts PKM2 expression in lung adenocarcinoma.

Positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) is widely used in the management of lung adenocarcinoma. Pyruvate kinase M2 (PKM2) plays a key role in glycolysis. We therefore investigated whether PKM2 expression affects 18F-FDG uptake in a retrospective analysis of 76 patients who underwent 18F-FDG PET/computed tomography (CT) scans for staging before surgical resection. We found that PKM2 expression was higher in tumors than peritumoral tissue (p < 0.05). Patients with high PKM2 expression had reduced overall (p < 0.05) and disease-free (p < 0.05) survival as compared to those with low PKM2 expression. Comparison of the primary tumor maximum standardized uptake value (SUVmax) between patients with high and low PKM2 expression revealed that the SUVmax was higher in primary tumors with high PKM2 expression than low PKM2 expression (p < 0.05). Multivariate analysis confirmed the association between SUVmax and PKM2 expression (p < 0.05). PKM2 status was predicted with 81.6% accuracy when the SUVmax cutoff value of 6.4. Thus,18F-FDG PET/CT is predictive of the PKM2 status in lung adenocarcinoma patients and could aid in determining therapeutic strategies.

D-Glyceraldehyde-3-Phosphate Dehydrogenase Structure and Function.

Aside from its well-established role in glycolysis, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been shown to possess many key functions in cells. These functions are regulated by protein oligomerization , biomolecular interactions, post-translational modifications , and variations in subcellular localization . Several GAPDH functions and regulatory mechanisms overlap with one another and converge around its role in intermediary metabolism. Several structural determinants of the protein dictate its function and regulation. GAPDH is ubiquitously expressed and is found in all domains of life. GAPDH has been implicated in many diseases, including those of pathogenic, cardiovascular, degenerative, diabetic, and tumorigenic origins. Understanding the mechanisms by which GAPDH can switch between its functions and how these functions are regulated can provide insights into ways the protein can be modulated for therapeutic outcomes.

Molecular And 3D-Structural Characterization Of Fructose-1,6-Bisphosphate Aldolase Derived From Metroxylon Sagu

Fructose-1,6-bisphosphate aldolase (FBAld) is an enzyme that catalyzes the cleavage of D-fructose-1,6-phosphate (FBP) to D-glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP), and plays vital role in glycolysis and gluconeogenesis. However, molecular characterization and functional roles of FBAld remain unknown in sago palm. Here we report a modified CTAB-RNA extraction method was developed for the isolation of good quality RNA (RIN>8) from sago leaves and the isolation of FBAld cDNA from sago palm. The isolated sago FBAld (msFBAld) cDNA has total length of 1288 bp with an open reading frame of 1020 bp and a predicted to encode for a protein of 340 amino acid resides. The predicted protein shared a high degree of homology with Class-I FBAld from other plants. Meanwhile, the msFBAld gene spanned 2322 bp and consisted of five exons. Conserved domain search identified fifteen catalytically important amino acids at the active site and phylogenetic tree revealed localization of msFBAld in the chloroplast. A molecular 3D-structure of msFBAld was generated by homology modeling and a Ramachandran plot with 86.7% of the residues in the core region, 13.4% in the allowed region with no residues in the disallowed region. The modeled structure is a homotetramer containing an /-TIM-barrel at the center. Superimposition of the model with Class-I aldolases identified a catalytic dyad, Lys209-Glu167, which could be involved in the Schiff's base formation and aldol condensation. Apart from that, overproduction of the recombinant msFBAld in Escherichia coli resulted in increased tolerance towards salinity.

Abstract 14: A switch in metabolic phenotype in vemurafenib-resistant melanoma cells to increased amino acid dependence serves as an alternate mechanism for survival

Abstract Despite considerable progress in the understanding of melanoma, and an increase in overall survival, resistance ultimately develops in most patients treated with BRAF inhibitors. To study the molecular mechanism(s) involved in acquired resistance, we generated a Vemurafenib-resistant A2-1b cell line in the BRAFV600E mutated SK-Mel28 melanoma cell background. Viability assays established IC50 of parental SK-Mel28 cells as 0.2 μM, while IC50&amp;gt;12 μM was noted for Vemurafenib-resistant A2-1b cells. Utilizing a quantitative proteomic strategy, profiling of A2-1b versus SK-Mel28 cells resulted in positive identification of 1720 proteins (≤1% FDR). Analysis of this data set identified a subset of 13 proteins, including Enolase 2, Triose-phosphate isomerase and Glyceraldehyde-3-phosphate dehydrogenase with a role in glycolysis, gluconeogenesis and NADH repair, to be differentially regulated in resistant cells. Additional studies validated significantly decreased Enolase 1 and 2 protein expression, suppressed glucose uptake and reduced lactic acid levels in resistant A2-1b cells. The pentose phosphate pathway, in contrast to citric acid cycle intermediates, was unaffected while the latter was significantly suppressed in resistant cells. The energy status of cells was similar as evidenced by equivalent total adenylate, guanylate, NADH, NADP+ and NADPH levels. Flux experiments measuring extracelluar acidification and oxygen consumption rates demonstrated that resistant A2-1b cells are unable to efficiently utilize intrinsic or exogenous fatty acids to meet energy demands. However, A2-1b cells maintained in media deprived of arginine and lysine exhibited increased basal and maximal respiration indicative of an energy reserve that relies on amino acid metabolism. Finally, metabolomics studies showing an overall increase in the absolute concentrations of gluconeogenic and ketogenic amino acids along with significantly elevated S6Kinase expression signify a shift from glucose to amino acids as the major energy source, in resistant A2-1b cells. Our data are consistent with a model of prolonged treatment response in which de-repression of ERK-MAPK pathway activity upon emergence of resistance to Vemurafenib is associated with adaptive changes in cellular metabolism. Sensitivity to BRAF inhibitors in the context of melanoma may not be defined by a reliance on glycolysis for survival, and that switch in metabolic phenotype can serve as an alternate mechanism for cell survival. Citation Format: Deeba N. Syed, Rahul K. Lall, Yong Wei Soon, Ahmed Aljohani, Changan Guo, Feng Liu, Frank L. Meyskens, James M. Ntambi, Hasan Mukhtar. A switch in metabolic phenotype in vemurafenib-resistant melanoma cells to increased amino acid dependence serves as an alternate mechanism for survival. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 14.

Abstract 1009: Metabolic reprogramming discriminates aggressive vs. slowly growing preneoplastic lesions at early stages of HCC development

Abstract Introduction and aim: Among the several changes underlying metabolic reprogramming of cancer cells, increased glucose utilization and its uncoupling from oxygen availability is a well-established phenomenon and has been recognized as a hallmark of cancer. To what extent these metabolic changes are important for the progression of slow growing tumors and whether a metabolic rewiring occurs in the very early stages of neoplastic progression represent key questions on the significance of these metabolic alterations in cancer. Here, we compared the metabolic features of preneoplastic hepatic lesions with those of advanced hepatocellular carcinomas (HCCs) and of proliferating liver, following partial hepatectomy (PH). Materials and Methods: Expression levels, activity and modulation of several enzymes with key roles in glycolysis, pentose phosphate pathway (PPP) and oxidative phosphorylation (OXPHOS) were assessed in preneoplastic hepatic lesions and HCC, induced in rats exposed to the Resistant-Hepatocyte (R-H) model. In vitro experiments were performed on HCC cells obtained by perfusion of HCC-bearing rats. Expression of metabolic genes was also investigated in two different cohorts of human patients carrying HCC. Results and discussion: A switch from OXPHOS to PPP was observed in very early preneoplastic lesions generated 10 weeks after the treatment with DENA. Notably, this metabolic reprogramming was observed only in the most aggressive preneoplastic lesions, characterized by positivity for cytokeratin 19 (CK-19+). PPP induction, shown by a strong increase in the expression and activity of glucose 6-phosphate dehydrogenase (G6PD) was supported both by inhibition of pyruvate kinase activity and by TP53-inducible glycolysis and apoptosis regulator (TIGAR) induction. Importantly, such metabolic rewiring was not observed in normal hepatocytes, undergoing proliferation following 2/3 partial hepatectomy (PH). Activation of the NRF2/KEAP1 pathway and down-regulation of miR-1 accompanied the metabolic reprogramming in CK-19+ preneoplastic lesions. Accordingly, NRF2 silencing decreased G6PD and increased miR-1 expression, consequently inhibiting PPP, while forced expression of miR-1 downregulated G6PD expression in HCC cells. Finally, an inverse correlation between miR-1 and its target gene G6PD was found in human HCC patients. Conclusion: These results demonstrate that metabolic reprogramming takes place at early stages of hepatocarcinogenesis and is likely the consequence of the concomitant activation of the NRF2-KEAP1 pathway. Citation Format: Marta A. Kowalik, Giulia Guzzo, Andrea Morandi, Andrea Perra, Silvia Menegon, Ionica Masgras, Elena Trevisan, Maria M. Angioni, Francesca Fornari, Luca Quagliata, Giovanna M. Ledda-Columbano, Laura Gramantieri, Luigi Terracciano, Silvia Giordano, Paola Chiarugi, Andrea Rasola, Amedeo Columbano. Metabolic reprogramming discriminates aggressive vs. slowly growing preneoplastic lesions at early stages of HCC development. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1009.

Abstract 704: Hyperglycemia stimulates glycolysis and enhances migratory/invasive potential in tongue squamous cell carcinoma

Abstract Objective: The aim of this study was to investigate the role of glycolysis (HK2/PKM2) in the development of tongue squamous cell carcinoma (TSCC) and elucidate how hyperglycaemia stimulate HK2 and PKM2 and enhance migration/invasion potential in TSCC. Methods: A total of 501 patients which diagnosed as TSCC between 1998 and 2004 were enrolled in the retrospective study. The expression of HK2/PKM2 was examined by IHC and the relationship between TSCC and diabetes mellitus (DM) was investigated. We then investigated the role of HK2/PKM2 in the migration and invasion of TSCC and relevant pathways (the SOD2-H2O2 pathway and miR-138 pathway). Finally, we investigated whether hyperglycaemia enhance migratory/invasive potential of TSCC through stimulating glycolysis. Results: The prevalent rate of TSCC patients with diabetes was 13.97%, which was significantly higher than the incidence rate of DM (11.6%) in China. Cox analysis revealed that the HR for patients with DM vs without DM was 1.32. IHC results confirmed that the up-regulation of PKM2/HK2 expression was correlated with tumor stage, clinical stages, diabetes, lymph node metastasis and associated with reduced overall survival. PKM2/HK2/AKT1 overexpression increased cell migration and invasion, SOD2 activities and intracellular H2O2. The siRNA-based PKM2/HK2 knockdown inhibited cell migration and invasion, reduced activities of SOD2 and intracellular H2O2, and also inhibited tumor growth and lung metastasis in vivo. Luciferase assays revealed that PKM2/AKT1 was directly targeted by miR-138 and miR-138 can reduce the expression of the PKM2/AKT1 gene. High glucose enhanced the migration/invasion ability, miR-138/PKM2/HK2 expression and increased SOD2 activities and intracellular H2O2. Conclusions: Our results confirm that DM may be a risk factor in the development of TSCC. PKM2/HK2 plays an important role in the progression of TSCC, and may serve as a biomarker or therapeutic target for patients with TSCC. High glucose stimulates glycolysis (PKM2/HK2) and enhances migration/invasion potential in TSCC. Citation Format: Anxun Wang, Wei Wang, Luodan Zhao, Qianting He, Jingjing Sun, Zhonghua Liu, Zujian Chen, Xiaofeng Zhou. Hyperglycemia stimulates glycolysis and enhances migratory/invasive potential in tongue squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 704.

Purification and characterization of glyceraldehyde-3-phosphate-dehydrogenase (GAPDH) from pea seeds

Glyceraldehyde-3-phosphate dehydrogenase [GAPDH, NAD + oxidoreductase (phosphorylating) 1.2.1.12] catalyzes the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate coupled with the reduction of NAD+ to NADH. In addition to its role in glycolysis, this enzyme has numerous alternate functions, in both prokaryotes and eukaryotes. In plants, additional functions have been reported from multiple species including Pisum sativum. A recent study has identified that GAPDH may play an important role in seed ageing and programmed cell death. Despite this the existing purification protocols are almost 40 years old, and only partial characterization of the enzyme has been reported. In the current study, we report a modified method for purification of enzymatically active pea seed GAPDH along with the characterization of the enzyme. Using 2D gel electrophoresis our study also demonstrates that pea seeds contain four isoforms of NAD+ dependent GAPDH.

Comprehensive structural analysis of the open and closed conformations of Theileria annulata enolase by molecular modelling and docking

Theileria annulata is an apicomplexan parasite which is responsible for tropical theileriosis in cattle. Due to resistance of T. annulata against commonly used antitheilerial drug, new drug candidates should be identified urgently. Enolase might be a druggable protein candidate which has an important role in glycolysis, and could also be related to several cellular functions as a moonlight protein. In this study; we have described three-dimensional models of open and closed conformations of T. annulata enolase by homology modeling method for the first time with the comprehensive domain, active site and docking analyses. Our results show that the enolase has similar folding patterns within enolase superfamily with conserved catalytic loops and active site residues. We have described specific insertions, possible plasminogen binding sites, electrostatic potential surfaces and positively charged pockets as druggable regions in T. annulata enolase.