Metabolism strikes back: metabolic flux regulates cell signaling

Lectin binding to pectoral fin of neonate little skates reared under ambient and projected-end-of-century temperature regimes

The glycosylation of macromolecules can vary both among tissue structural components and by adverse conditions, potentially providing an alternative marker of stress in organisms. Lectins are proteins that bind carbohydrate moieties and lectin histochemistry is a common method to visualize microstructures in biological specimens and diagnose pathophysiological states in human tissues known to alter glycan profiles. However, this technique is not commonly used to assess broad-spectrum changes in cellular glycosylation in response to environmental stressors. In addition, the binding of various lectins has not been studied in elasmobranchs (sharks, skates, and rays). We surveyed the binding tissue structure specificity of 14 plant-derived lectins, using both immunoblotting and immunofluorescence, in the pectoral fins of neonate little skates (Leucoraja erinacea). Skates were reared under present-day or elevated (+5°C above ambient) temperature regimes and evaluated for lectin binding as an indicator of changing cellular glycosylation and tissue structure. Lectin labeling was highly tissue and microstructure specific. Dot blots revealed no significant changes in lectin binding between temperature regimes. In addition, lectins only detected in the elevated temperature treatment were Canavalia ensiformis lectin (Concanavalin A) in spindle cells of muscle and Ricinus communis agglutinin in muscle capillaries. These results provide a reference for lectin labeling in elasmobranch tissue that may aid future investigations.

Use of single analytic tool to quantify both absolute N-glycosylation and glycan distribution in monoclonal antibodies

Recombinant proteins represent almost half of the top selling therapeutics-with over a hundred billion dollars in global sales-and their efficacy and safety strongly depend on glycosylation. In this study, we showcase a simple method to simultaneously analyze N-glycan micro- and macroheterogeneity of an immunoglobulin G (IgG) by quantifying glycan occupancy and distribution. Our approach is linear over a wide range of glycan and glycoprotein concentrations down to 25 ng/mL. Additionally, we present a case study demonstrating the effect of small molecule metabolic regulators on glycan heterogeneity using this approach. In particular, sodium oxamate (SOD) decreased Chinese hamster ovary (CHO) glucose metabolism and reduced IgG glycosylation by 40% through upregulating reactive oxygen species (ROS) and reducing the UDP-GlcNAc pool, while maintaining a similar glycan profile to control cultures. Here, we suggest glycan macroheterogeneity as an attribute should be included in bioprocess screening to identify process parameters that optimize culture performance without compromising antibody quality.

Amino acid metabolic reprogramming in tumor metastatic colonization

Metastasis is considered as the major cause of cancer death. Cancer cells can be released from primary tumors into the circulation and then colonize in distant organs. How cancer cells acquire the ability to colonize in distant organs has always been the focus of tumor biology. To enable survival and growth in the new environment, metastases commonly reprogram their metabolic states and therefore display different metabolic properties and preferences compared with the primary lesions. For different microenvironments in various colonization sites, cancer cells must transfer to specific metabolic states to colonize in different distant organs, which provides the possibility of evaluating metastasis tendency by tumor metabolic states. Amino acids provide crucial precursors for many biosynthesis and play an essential role in cancer metastasis. Evidence has proved the hyperactivation of several amino acid biosynthetic pathways in metastatic cancer cells, including glutamine, serine, glycine, branched chain amino acids (BCAAs), proline, and asparagine metabolism. The reprogramming of amino acid metabolism can orchestrate energy supply, redox homeostasis, and other metabolism-associated pathways during cancer metastasis. Here, we review the role and function of amino acid metabolic reprogramming in cancer cells colonizing in common metastatic organs, including lung, liver, brain, peritoneum, and bone. In addition, we summarize the current biomarker identification and drug development of cancer metastasis under the amino acid metabolism reprogramming, and discuss the possibility and prospect of targeting organ-specific metastasis for cancer treatment.

O-GlcNAc transferase modulates the cellular endocytosis machinery by controlling the formation of clathrin-coated pits

Clathrin-mediated endocytosis (CME) controls the internalization and function of a wide range of cell surface proteins. CME occurs by the assembly of clathrin and many other proteins on the inner leaflet of the plasma membrane into clathrin-coated pits (CCPs). These structures recruit specific cargo destined for internalization, generate membrane curvature, and in many cases undergo scission from the plasma membrane to yield intracellular vesicles. The diversity of functions of cell surface proteins controlled via internalization by CME may suggest that regulation of CCP formation could be effective to allow cellular adaptation under different contexts. Of interest is how cues derived from cellular metabolism may regulate CME, given the reciprocal role of CME in controlling cellular metabolism. The modification of proteins with O-linked β-GlcNAc (O-GlcNAc) is sensitive to nutrient availability and may allow cellular adaptation to different metabolic conditions. Here, we examined how the modification of proteins with O-GlcNAc may control CCP formation and thus CME. We used perturbation of key enzymes responsible for protein O-GlcNAc modification, as well as specific mutants of the endocytic regulator AAK1 predicted to be impaired for O-GlcNAc modification. We identify that CCP initiation and the assembly of clathrin and other proteins within CCPs are controlled by O-GlcNAc protein modification. This reveals a new dimension of regulation of CME and highlights the important reciprocal regulation of cellular metabolism and endocytosis.

PVT1/miR-145-5p/HK2 modulates vascular smooth muscle cells phenotype switch via glycolysis: The new perspective on the spiral artery remodeling

INTRODUCTION

Vascular smooth muscle cells (VSMC) switched from a contractile phenotype to a synthetic phenotype during the decidual spiral artery (SPAs) remodeling process. The lncRNA plasmacytoma variant translocation 1 (PVT1) and glucose metabolism have been found to regulate the VSMC phenotype switch. This study aimed to analyze the dynamic expression of PVT1 and glycolytic key enzymes hexokinase2 (HK2) at different remodeling stages in early human pregnancy and elucidate the underlying mechanism of the PVT1/miR-145-5p/HK2 axis involved in the spiral artery remodeling.

METHODS

qRT-PCR, Western blot (WB) analysis, Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) were used to detect the expression and localization of PVT1 and HK2 in decidual tissue. HA-VSMCs were transfected with specific siRNA, shRNA and plasmids to regulate corresponding genes. Extracellular lactate, cellular ATP, ROS, and intracellular NADPH levels were measured using the corresponding assay kits. Migration was measured by wound-healing and Transwell assays. Contractile phenotypic markers α-SMA, MYH11 with calponin and synthetic phenotypic markers OPN and vimentin were detected by WB. The PDC model was used to detect the degree of spiral arterial remodeling.

RESULTS

PVT1 and HK2 were upregulated with gestational age (GA) increasing in decidual tissue during the early pregnancy. HK2 regulated the glycolytic activity and VSMC phenotype switch in vitro. PVT1 regulated the glycolytic activity and VSMC phenotype switch through HK2. PVT1 played a ceRNA role in regulating HK2 expression by sponging miR-145-5p. PVT1 and HK2 influenced spiral artery remodeling in the PDC model.

DISCUSSION

PVT1 and HK2 were upregulated, and miR-145-5p was downregulated in decidua with the GA increasing. Meanwhile, the PVT1/miR-145-5p/HK2 axis may be involved in regulating the phenotypic switch and migratory capacity of VSMCs by affecting glycolysis in decidual SPAs remodeling.

Phenotypic plasticity of vascular smooth muscle cells in vascular calcification: Role of mitochondria

Vascular calcification (VC) is an important hallmark of cardiovascular disease, the osteo-/chondrocyte phenotype differentiation of vascular smooth muscle cells (VSMCs) is the main cause of vascular calcification. Accumulating evidence shows that mitochondrial dysfunction may ultimately be more detrimental in the VSMCs calcification. Mitochondrial participate in essential cellular functions, including energy production, metabolism, redox homeostasis regulation, intracellular calcium homeostasis, apoptosis, and signal transduction. Mitochondrial dysfunction under pathological conditions results in mitochondrial reactive oxygen species (ROS) generation and metabolic disorders, which further lead to abnormal phenotypic differentiation of VSMCs. In this review, we summarize existing studies targeting mitochondria as a treatment for VC, and focus on VSMCs, highlighting recent progress in determining the roles of mitochondrial processes in regulating the phenotype transition of VSMCs, including mitochondrial biogenesis, mitochondrial dynamics, mitophagy, mitochondrial energy metabolism, and mitochondria/ER interactions. Along these lines, the impact of mitochondrial homeostasis on VC is discussed.

Identification of hexosamine biosynthesis pathway as a novel prognostic signature and its correlation with immune infiltration in bladder cancer

Background: Urinary bladder cancer (UBC) is one of the common urological malignancies, lacking reliable biomarkers to predict clinical outcomes in UBC patients. Thus, it is needed to identify the novel diagnostic/prognostic biomarkers to stratify the high-risk UBC patients. As a shunt pathway of glycolysis, the hexosamine biosynthesis pathway (HBP) has been implicated in carcinogenesis. However, its prognostic value in UBC remains unclear.

Methods: The RNA sequencing and mRNA microarray datasets were downloaded from The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus databases. The expression levels of five HBP genes were analyzed in normal and UBC samples, and their associations with stage, grade and survival were plotted. The performance of HBP risk group was evaluated by receiver-operating characteristics (ROC) curve. The HBP signature was generated by Gene Set Variation Analysis (GSVA) and its association with clinicopathological parameters and survival were analyzed. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were carried out to examine the potential biological functions of HBP using DAVID online tool. The infiltration estimation fraction of immune cells was performed using CIBERSORT-ABS algorithm. Gene set enrichment analysis (GSEA) was used to explore the potential function of HBP in tumor immunoregulation.

Results: Four HBP genes were upregulated in UBCs compared to normal tissues in TCGA-BLCA dataset. The upregulation of all five HBP genes was significantly associated with tumor grade and stage of UBC in three independent UBC datasets. The expression of HBP genes predicted poor clinical outcomes in UBC patients in both TCGA-BLCA and GSE13507 datasets. The high-risk group based on HBP genes showed a poor prognosis. Furthermore, HBP signature was positively associated with tumor grade and stage in TCGA-BLCA dataset and with tumor grade, stage, distal metastasis and poor survival in GSE13507 dataset. Interestingly, high-HBP signature group exhibited a high infiltration of immune cells, particularly the macrophage population.

Conclusion: We identified that HBP was a promising prognostic biomarker in UBC patients and strongly associated with immune infiltration.

PGM3 regulates beta-catenin activity to promote colorectal cancer cell progression

The hexosamine biosynthetic pathway (HBP) is connected to abnormal N- and O-linked protein glycosylation in cancer, which performs critical roles in tumorigenesis. However, the regulation mechanisms of HBP and its role in colorectal cancer (CRC) progression remain unexplained. This study analyzed the expression level of phosphoglucomutase 3 (PGM3), a key enzyme in HBP, and identified its function in CRC cell lines. Analysis of publicly available CRC microarray data determined that PGM3 is upregulated in CRC tumor tissues. Furthermore, functional experiments emphasized the significant roles of PGM3 in facilitating CRC cell proliferation and migration. Mechanistically, we demonstrated that the activity of β-catenin in CRC was maintained by PGM3-mediated O-GlcNAcylation. PGM3 knockdown or inhibition of O-GlcNAc transferase decreased β-catenin activity and the expression levels of its downstream targets. Collectively, our findings indicate that PGM3 exhibits tumor-promoting roles by elevating O-GlcNAcylation level and maintaining β-catenin activity, and might serve as a prognostic biomarker and treatment target in CRC.

The crosstalk of the human microbiome in breast and colon cancer: A metabolomics analysis

The human microbiome's role in colon and breast cancer is described in this review. Understanding how the human microbiome and metabolomics interact with breast and colon cancer is the chief area of this study. First, the role of the gut and distal microbiome in breast and colon cancer is investigated, and the direct relationship between microbial dysbiosis and breast and colon cancer is highlighted. This work also focuses on the many metabolomic techniques used to locate prospective biomarkers, make an accurate diagnosis, and research new therapeutic targets for cancer treatment. This review clarifies the influence of anti-tumor medications on the microbiota and the proactive measures that can be taken to treat cancer using a variety of therapies, including radiotherapy, chemotherapy, next-generation biotherapeutics, gene-based therapy, integrated omics technology, and machine learning.

Targeting cellular energy metabolism- mediated ferroptosis by small molecule compounds for colorectal cancer therapy

Alterations in cellular energy metabolism, including glycolysis, glutamine and lipid metabolism that affects ferroptosis in the tumour microenvironment (TME), play a critical role in the development and progression of colorectal cancer (CRC) and offer evolutionary advantages to tumour cells and even enhance their aggressive phenotype. This review summarises the findings on the dysregulated energy metabolism pathways, including lipid and fatty acid metabolism especially for regulating the ferroptosis in TME. Moreover, the cellular energy metabolism and tumour ferroptosis to be regulated by small molecule compounds, which targeting the different aspects of metabolic pathways of energy production as well as metabolic enzymes that connect with the tumour cell growth and ferroptosis in CRC are also discussed. In this review, we will provide a comprehensive summary on small molecule compounds regulatory function of different energy metabolic routes on ferroptosis in tumour cells and discuss those metabolic vulnerabilities for the development of potential ferroptosis-based tumour therapies for colorectal cancer.

Metabolic control of epigenetic rearrangements in B cell pathophysiology

Both epigenetic and metabolic reprogramming guide lymphocyte differentiation and can be linked, in that metabolic inputs can be integrated into the epigenome to inform cell fate decisions. This framework has been thoroughly investigated in several pathophysiological contexts, including haematopoietic cell differentiation. In fact, metabolite availability dictates chromatin architecture and lymphocyte specification, a multi-step process where haematopoietic stem cells become terminally differentiated lymphocytes (effector or memory) to mount the adaptive immune response. B and T cell precursors reprogram their cellular metabolism across developmental stages, not only to meet ever-changing energetic demands but to impose chromatin accessibility and regulate the function of master transcription factors. Metabolic control of the epigenome has been extensively investigated in T lymphocytes, but how this impacts type-B life cycle remains poorly appreciated. This assay will review our current understanding of the connection between cell metabolism and epigenetics at crucial steps of B cell maturation and how its dysregulation contributes to malignant transformation.

Mitochondrial calcium exchange in physiology and disease

The uptake of calcium into and extrusion of calcium from the mitochondrial matrix is a fundamental biological process that has critical effects on cellular metabolism, signaling, and survival. Disruption of mitochondrial calcium (mCa2+) cycling is implicated in numerous acquired diseases such as heart failure, stroke, neurodegeneration, diabetes, and cancer and is genetically linked to several inherited neuromuscular disorders. Understanding the mechanisms responsible for mCa2+ exchange therefore holds great promise for the treatment of these diseases. The past decade has seen the genetic identification of many of the key proteins that mediate mitochondrial calcium uptake and efflux. Here, we present an overview of the phenomenon of mCa2+ transport and a comprehensive examination of the molecular machinery that mediates calcium flux across the inner mitochondrial membrane: the mitochondrial uniporter complex (consisting of MCU, EMRE, MICU1, MICU2, MICU3, MCUB, and MCUR1), NCLX, LETM1, the mitochondrial ryanodine receptor, and the mitochondrial permeability transition pore. We then consider the physiological implications of mCa2+ flux and evaluate how alterations in mCa2+ homeostasis contribute to human disease. This review concludes by highlighting opportunities and challenges for therapeutic intervention in pathologies characterized by aberrant mCa2+ handling and by summarizing critical unanswered questions regarding the biology of mCa2+ flux.

Slt2 Is Required to Activate ER-Stress-Protective Mechanisms through TORC1 Inhibition and Hexosamine Pathway Activation

Slt2, the MAPK of the cell wall integrity (CWI) pathway, connects different signaling pathways and performs different functions in the protective response of S. cerevisiae to stress. Previous work has evidenced the relation of the CWI pathway and the unfolded protein response (UPR), a transcriptional program activated upon endoplasmic reticulum (ER) stress. However, the mechanisms of crosstalk between these pathways and the targets regulated by Slt2 under ER stress remain unclear. Here, we demonstrated that ectopic expression of GFA1, the gene encoding the first enzyme in the synthesis of UDP-GlcNAc by the hexosamine biosynthetic pathway (HBP) or supplementation of the growth medium with glucosamine (GlcN), increases the tolerance of slt2 mutant cells to different ER-stress inducers. Remarkably, GlcN also alleviates the sensitivity phenotype of cells lacking IRE1 or HAC1, the main actors in controlling the UPR. The exogenous addition of GlcN reduced the abundance of glycosylated proteins and triggered autophagy. We also found that TORC1, the central stress and growth controller, is inhibited by tunicamycin exposure in cells of the wild-type strain but not in those lacking Slt2. Consistent with this, the tunicamycin-induced activation of autophagy and the increased synthesis of ATP in response to ER stress were absent by knock-out of SLT2. Altogether, our data placed Slt2 as an essential actor of the ER stress response by regulating the HBP activity and the TORC1-dependent signaling.

Mitochondrial connections with immune system in Zebrafish

Mitochondria are organelles commonly associated with adenosine triphosphate (ATP) formation through the oxidative phosphorylation (OXPHOS) process. However, mitochondria are also responsible for functions such as calcium homeostasis, apoptosis, autophagy, and production of reactive oxygen species (ROS) that, in conjunction, can lead to different cell fate decisions. Mitochondrial morphology changes rely on nutrients' availability and the bioenergetics demands of the cells, in a process known as mitochondrial dynamics, which includes both fusion and fission. This organelle senses the microenvironment and can modify the cells to either a pro or anti-inflammatory profile. The zebrafish has been increasingly used to research mitochondrial dynamics and its connection with the immune system since the pathways and molecules involved in these processes are conserved on this fish. Several genetic tools and technologies are currently available to analyze the behavior of mitochondria in zebrafish. However, even though zebrafish presents several similar processes known in mammals, the effect of the mitochondria in the immune system has not been so broadly studied in this model. In this review, we summarize the current knowledge in zebrafish studies regarding mitochondrial function and immuno metabolism.

Mechano-induced cell metabolism promotes microtubule glutamylation to force metastasis

Mechanical signals from the tumor microenvironment modulate cell mechanics and influence cell metabolism to promote cancer aggressiveness. Cells withstand external forces by adjusting the stiffness of their cytoskeleton. Microtubules (MTs) act as compression-bearing elements. Yet how cancer cells regulate MT dynamic in response to the locally constrained environment has remained unclear. Using breast cancer as a model of a disease in which mechanical signaling promotes disease progression, we show that matrix stiffening rewires glutamine metabolism to promote MT glutamylation and force MT stabilization, thereby promoting cell invasion. Pharmacologic inhibition of glutamine metabolism decreased MT glutamylation and affected their mechanical stabilization. Similarly, decreased MT glutamylation by overexpressing tubulin mutants lacking glutamylation site(s) decreased MT stability, thereby hampering cancer aggressiveness in vitro and in vivo. Together, our results decipher part of the enigmatic tubulin code that coordinates the fine-tunable properties of MT and link cell metabolism to MT dynamics and cancer aggressiveness.

Metabolic reprogramming due to hypoxia in pancreatic cancer: Implications for tumor formation, immunity, and more

Hypoxia is a common phenomenon in most malignant tumors, especially in pancreatic cancer (PC). Hypoxia is the result of unlimited tumor growth and plays an active role in promoting tumor survival, progression, and invasion. As the part of the hypoxia microenvironment in PC is gradually clarified, hypoxia is becoming a key determinant and an important therapeutic target of pancreatic cancer. To adapt to the severe hypoxia environment, cells have changed their metabolic phenotypes to maintain their survival and proliferation. Enhanced glycolysis is the most prominent feature of cancer cells' metabolic reprogramming in response to hypoxia. It provides the energy source for hypoxic cancer cells (although it provides less than oxidative phosphorylation) and produces metabolites that can be absorbed and utilized by normoxic cancer cells. In addition, the uptake of glutamine and fatty acids by hypoxic cancer cells is also increased, which is also conducive to tumor progression. Their metabolites are pooled in the hexosamine biosynthesis pathway (HBP). As a nutrition sensor, HBP, in turn, can coordinate glucose and glutamine metabolism. Its end product, UDP-GlcNAc, is the substrate of protein post-translational modification (PTM) involved in various signaling pathways supporting tumor progression. Adaptive metabolic changes of cancer cells promote their survival and affect tumor immune cells in the tumor microenvironment (TME), which contributes to tumor immunosuppressive microenvironment and induces tumor immunotherapy resistance. Here, we summarize the hypoxic microenvironment, its effect on metabolic reprogramming, and its contribution to immunotherapy resistance in pancreatic cancer.

The hexosamine biosynthetic pathway and cancer: Current knowledge and future therapeutic strategies

The hexosamine biosynthetic pathway (HBP) is a glucose metabolism pathway that results in the synthesis of a nucleotide sugar UDP-GlcNAc, which is subsequently used for the post-translational modification (O-GlcNAcylation) of intracellular proteins that regulate nutrient sensing and stress response. The HBP is carried out by a series of enzymes, many of which have been extensively implicated in cancer pathophysiology. Increasing evidence suggests that elevated activation of the HBP may act as a cancer biomarker. Inhibition of HBP enzymes could suppress tumor cell growth, modulate the immune response, reduce resistance, and sensitize tumor cells to conventional cancer therapy. Therefore, targeting the HBP may serve as a novel strategy for treating cancer patients. Here, we review the current findings on the significance of HBP enzymes in various cancers and discuss future approaches for exploiting HBP inhibition for cancer treatment.

Metabolic ROS Signaling: To Immunity and Beyond

Metabolism is a critical determinant of immune cell functionality. Immunometabolism, by definition, is a multidisciplinary area of immunology research that integrates the knowledge of energy transduction mechanisms and biochemical pathways. An important concept in the field is metabolic switch, a transition of immune cells upon activation to preferential utilization of select catabolic pathways for their energy needs. Mitochondria are not inert in this process and contribute to the metabolic adaptation by different mechanisms which include increasing ATP production to match dynamic bioenergetic demands and serving as a signaling platform. The latter involves generation of reactive oxygen species (ROS), one of the most intensively studied mitochondrial processes. While the role of mitochondrial ROS in the context of oxidative stress is well established, ROS signaling in immunity is an emerging and quickly changing field. In this review, we discuss ROS signaling and immunometabolism concepts from the standpoint of bioenergetics. We also provide a critical insight into the methodology for ROS assessment, outlining current challenges in the field. Finally, based on our analysis of the literature data, we hypothesize that regulatory ROS production, as opposed to oxidative stress, is controlled by mitochondrial biogenesis rather than metabolic switches.

Exploring plasma metabolomic changes in sepsis: a clinical matching study based on gas chromatography-mass spectrometry

Background

Sepsis is a deleterious systemic inflammatory response to infection, and despite advances in treatment, the mortality rate remains high. We hypothesized that plasma metabolism could clarify sepsis in patients complicated by organ dysfunction.

Methods

Plasma samples from 31 patients with sepsis and 23 healthy individuals of comparable age, gender, and body mass index (BMI) were collected. Plasma metabolites were detected through gas chromatography–mass spectrometry (GC–MS), and relevant metabolic pathways were predicted using the Kyoto Encyclopedia of Genes and Genomics (KEGG) pathway database. Student’s t-test was employed for statistical analysis. In addition, to explore sepsis organ dysfunction, plasma samples of sepsis patients were further analyzed by metabolomics subgroup analysis according to organ dysfunction.

Results

A total of 222 metabolites were detected, which included 124 metabolites with statistical significance between the sepsis and control groups. Among these, we found 26 were fatty acids, including 3 branched fatty acids, 10 were saturated fatty acids, and 13 were unsaturated fatty acids that were found in sepsis plasma samples but not in the controls. In addition, 158 metabolic pathways were predicted, 74 of which were significant. Further subgroup analysis identified seven metabolites in acute kidney injury (AKI), three metabolites in acute respiratory distress syndrome (ARDS), seven metabolites in sepsis-induced myocardial dysfunction (SIMD), and four metabolites in acute hepatic ischemia (AHI) that were significantly different. The results showed that the sepsis samples exhibited extensive changes in amino acids, fatty acids, and tricarboxylic acid (TCA)–cycle products. In addition, three metabolic pathways—namely, energy metabolism, amino acid metabolism, and lipid metabolism—were downregulated in sepsis patients.

Conclusions

The downregulated energy, amino acid, and lipid metabolism found in our study may serve as a novel clinical marker for the dysregulated internal environment, particularly involving energy metabolism, which results in sepsis.

Unstructured regions of large enzymatic complexes control the availability of metabolites with signaling functions

Metabolites produced via traditional biochemical processes affect intracellular communication, inflammation, and malignancy. Unexpectedly, acetyl-CoA, α-ketoglutarate and palmitic acid, which are chemical species of reactions catalyzed by highly abundant, gigantic enzymatic complexes, dubbed as "metabolons", have broad "nonmetabolic" signaling functions. Conserved unstructured regions within metabolons determine the yield of these metabolites. Unstructured regions tether functional protein domains, act as spatial constraints to confine constituent enzyme communication, and, in the case of acetyl-CoA production, tend to be regulated by intricate phosphorylation patterns. This review presents the multifaceted roles of these three significant metabolites and describes how their perturbation leads to altered or transformed cellular function. Their dedicated enzymatic systems are then introduced, namely, the pyruvate dehydrogenase (PDH) and oxoglutarate dehydrogenase (OGDH) complexes, and the fatty acid synthase (FAS), with a particular focus on their structural characterization and the localization of unstructured regions. Finally, upstream metabolite regulation, in which spatial occupancy of unstructured regions within dedicated metabolons may affect metabolite availability and subsequently alter cell functions, is discussed. Video abstract.

Metabolomic and Signaling Programs Induced by Immobilized versus Soluble IFN γ in Neural Stem Cells

Neural stem cells (NSCs) provide a strategy to replace damaged neurons following traumatic central nervous system injuries. A major hurdle to translation of this therapy is that direct application of NSCs to CNS injury does not support sufficient neurogenesis due to lack of proper cues. To provide prolonged spatial cues to NSCs IFN-γ was immobilized to biomimetic hydrogel substrate to supply physical and biochemical signals to instruct the encapsulated NSCs to be neurogenic. However, the immobilization of factors, including IFN-γ, versus soluble delivery of the same factor, has been incompletely characterized especially with respect to activation of signaling and metabolism in cells over longer time points. In this study, protein and metabolite changes in NSCs induced by immobilized versus soluble IFN-γ at 7 days were evaluated. Soluble IFN-γ, refreshed daily over 7 days, elicited stronger responses in NSCs compared to immobilized IFN-γ, indicating that immobilization may not sustain signaling or has altered ligand/receptor interaction and integrity. However, both IFN-γ delivery types supported increased βIII tubulin expression in parallel with canonical and noncanonical receptor-signaling compared to no IFN-γ. Global metabolomics and pathway analysis revealed that soluble and immobilized IFN-γ altered metabolic pathway activities including energy, lipid, and amino acid synthesis, with soluble IFN-γ having the greatest metabolic impact overall. Finally, soluble and immobilized IFN-γ support mitochondrial voltage-dependent anion channel (VDAC) expression that correlates to differentiated NSCs. This work utilizes new methods to evaluate cell responses to protein delivery and provides insight into mode of action that can be harnessed to improve regenerative medicine-based strategies.

UDP-glucose 6-dehydrogenase knockout impairs migration and decreases in vivo metastatic ability of breast cancer cells

Dysregulated metabolism is a hallmark of cancer that supports tumor growth and metastasis. One understudied aspect of cancer metabolism is altered nucleotide sugar biosynthesis, which drives aberrant cell surface glycosylation known to support various aspects of cancer cell behavior including migration and signaling. We examined clinical association of nucleotide sugar pathway gene expression and found that UGDH, encoding UDP-glucose 6-dehydrogenase which catalyzes production of UDP-glucuronate, is associated with worse breast cancer patient survival. Knocking out the mouse homolog Ugdh in highly-metastatic 6DT1 breast cancer cells impaired migration ability without affecting in vitro proliferation. Further, Ugdh-KO resulted in significantly decreased metastatic capacity in vivo when the cells were orthotopically injected in syngeneic mice. Our experiments show that UDP-glucuronate biosynthesis is critical for metastasis in a mouse model of breast cancer.

Comparative Metabolites and Citrate-Degrading Enzymes Activities in Citrus Fruits Reveal the Role of Balance between ACL and Cyt-ACO in Metabolite Conversions

Citric acid metabolism is considered to be the central cellular process of metabolite conversions. ATP-citrate lyase (ACL) and cytosolic aconitase (cyt-ACO) are the two citrate-degrading enzymes that decide the carbon flux towards different metabolite biosynthesis pathways. However, the correlation of their activities with metabolite concentrations in citrus fruits is still unclear. Here, the concentrations of soluble sugars, organic acids, acetyl-CoA, flavonoids, carotenoids, and γ-aminobutyric acid, as well as the activities of ACL, cyt-ACO, acetyl-CoA C-acetyltransferase, and acetyl-CoA carboxylase, were compared among the fruits of six citrus cultivars during fruit development and ripening. The results showed that the correlation between citrate concentration and cyt-ACO or ACL activity varied greatly among cultivars, while the activities of cyt-ACO and ACL had a significantly negative correlation (r = −0.4431). Moreover, ACL overexpression and RNA interference in the Citrus callus indicated that increasing and decreasing the ACL activity could reduce and induce cyt-ACO activity, respectively. In addition, significant correlation was only observed between the ACL activity and the concentration of acetyl-CoA (r = 0.4333). Taken together, the present study suggested that ACL and cyt-ACO synergistically control the citrate fate for the biosynthesis of other metabolites, but they are not the key determinants for the accumulation of citrate, as well as other metabolites in citrus fruits.

Stem metabolism: Insights from oncometabolism and vice versa

Metabolism, is a transversal hot research topic in different areas, resulting in the integration of cellular needs with external cues, involving a highly coordinated set of activities in which nutrients are converted into building blocks for macromolecules, energy currencies and biomass. Importantly, cells can adjust different metabolic pathways defining its cellular identity. Both cancer cell and embryonic stem cells share the common hallmark of high proliferative ability but while the first represent a huge social-economic burden the second symbolize a huge promise. Importantly, research on both fields points out that stem cells share common metabolic strategies with cancer cells to maintain their identity as well as proliferative capability and, vice versa cancer cells also share common strategies regarding pluripotent markers. Moreover, the Warburg effect can be found in highly proliferative non-cancer stem cells as well as in embryonic stem cells that are primed towards differentiation, while a bivalent metabolism is characteristic of embryonic stem cells that are in a true naïve pluripotent state and cancer stem cells can also range from glycolysis to oxidative phosphorylation. Therefore, this review aims to highlight major metabolic similarities between cancer cells and embryonic stem cells demonstrating that they have similar strategies in both signaling pathways regulation as well as metabolic profiles while focusing on key metabolites.

mTOR Regulation of Metabolism in Hematologic Malignancies

Neoplastic cells rewire their metabolism, acquiring a selective advantage over normal cells and a protection from therapeutic agents. The mammalian Target of Rapamycin (mTOR) is a serine/threonine kinase involved in a variety of cellular activities, including the control of metabolic processes. mTOR is hyperactivated in a large number of tumor types, and among them, in many hematologic malignancies. In this article, we summarized the evidence from the literature that describes a central role for mTOR in the acquisition of new metabolic phenotypes for different hematologic malignancies, in concert with other metabolic modulators (AMPK, HIF1α) and microenvironmental stimuli, and shows how these features can be targeted for therapeutic purposes.

Metabolic Routes in Inflammation: The Citrate Pathway and its Potential as Therapeutic Target

Significant metabolic changes occur in inflammation to respond to the new energetic needs of cells. Mitochondria are addressed not only to produce ATP, but also to supply substrates, such citrate, to produce pro-inflammatory molecules. In this context, most of the citrate is diverted from Krebs cycle and channeled into the "citrate pathway" leading to the increase in the export of citrate into cytosol by the Mitochondrial Citrate Carrier (CIC) followed by its cleavage into acetyl-CoA and oxaloacetate by ATP Citrate Lyase (ACLY). Acetyl- CoA is used to produce PGE2 and oxaloacetate to make NADPH needed for NO and ROS production. In addition, cytosolic citrate also provides precursors for itaconate synthesis. Citrate- derived itaconate acts as a negative regulator of inflammation by modulating the synthesis of the inflammatory mediators. Inhibition of CIC or ACLY by different synthetic and natural molecules results in the reduction of NO, ROS and PGE2 levels suggesting that the citrate pathway can be a new target to be addressed in inflammation. Beneficial effects can be obtained also in the oxidative stress and inflammatory conditions observed in Down syndrome.

Non-enzymatic reaction of carnosine and glyceraldehyde-3-phosphate accompanies metabolic changes of the pentose phosphate pathway

OBJECTIVES

Carnosine (β-alanyl-l-histidine) is a naturally occurring dipeptide that selectively inhibits cancer cell growth, possibly by influencing glucose metabolism. As its precise mode of action and its primary targets are unknown, we analysed carnosine's effect on metabolites and pathways in glioblastoma cells.

MATERIALS AND METHODS

Glioblastoma cells, U87, T98G and LN229, were treated with carnosine, and metabolites were analysed by gas chromatography coupled with mass spectrometry. Furthermore, mitochondrial ATP production was determined by extracellular flux analysis and reaction products of carnosine were investigated using mass spectrometry.

RESULTS

Carnosine decreased the intracellular abundance of several metabolites indicating a reduced activity of the pentose phosphate pathway, the malate-aspartate shuttle and the glycerol phosphate shuttle. Mitochondrial respiration was reduced in U87 and T98G but not in LN229 cells, independent of whether glucose or pyruvate was used as substrate. Finally, we demonstrate non-enzymatic reaction of carnosine with dihydroxyacetone phosphate and glyceraldehyde-3-phosphate. However, glycolytic flux from glucose to l-lactate appeared not to be affected by the reaction of carnosine with the metabolites.

CONCLUSIONS

Carnosine reacts non-enzymatically with glycolytic intermediates reducing the activity of the pentose phosphate pathway which is required for cell proliferation. Although the activity of the malate-aspartate and the glycerol phosphate shuttle appear to be affected, reduced mitochondrial ATP production under the influence of the dipeptide is cell-specific and appears to be independent of the effect on the shuttles.

Metabolomic Analysis of Influenza A Virus A/WSN/1933 (H1N1) Infected A549 Cells during First Cycle of Viral Replication

Influenza A virus (IAV) has developed strategies to utilize host metabolites which, after identification and isolation, can be used to discover the value of immunometabolism. During this study, to mimic the metabolic processes of influenza virus infection in human cells, we infect A549 cells with H1N1 (WSN) influenza virus and explore the metabolites with altered levels during the first cycle of influenza virus infection using ultra-high-pressure liquid chromatography-quadrupole time-of-flight mass spectrometer (UHPLC-Q-TOF MS) technology. We annotate the metabolites using MetaboAnalyst and the Kyoto Encyclopedia of Genes and Genomes pathway analyses, which reveal that IAV regulates the abundance of the metabolic products of host cells during early infection to provide the energy and metabolites required to efficiently complete its own life cycle. These metabolites are correlated with the tricarboxylic acid (TCA) cycle and mainly are involved in purine, lipid, and glutathione metabolisms. Concurrently, the metabolites interact with signal receptors in A549 cells to participate in cellular energy metabolism signaling pathways. Metabonomic analyses have revealed that, in the first cycle, the virus not only hijacks cell metabolism for its own replication, but also affects innate immunity, indicating a need for further study of the complex relationship between IAV and host cells.

Biomaterial-Based Metabolic Regulation in Regenerative Engineering

Recent advances in cell metabolism studies have deepened the appreciation of the role of metabolic regulation in influencing cell behavior during differentiation, angiogenesis, and immune response in the regenerative engineering scenarios. However, the understanding of whether the intracellular metabolic pathways could be influenced by material-derived cues remains limited, although it is now well appreciated that material cues modulate cell functions. Here, an overview of how the regulation of different aspect of cell metabolism, including energy homeostasis, oxygen homeostasis, and redox homeostasis could contribute to modulation of cell function is provided. Furthermore, recent evidence demonstrating how material cues, including the release of inherent metabolic factors (e.g., ions, regulatory metabolites, and oxygen), tuning of the biochemical cues (e.g., inherent antioxidant properties, cell adhesivity, and chemical composition of nanomaterials), and changing in biophysical cues (topography and surface stiffness), may impact cell metabolism toward modulated cell behavior are discussed. Based on the resurgence of interest in cell metabolism and metabolic regulation, further development of biomaterials enabling metabolic regulation toward dictating cell function is poised to have substantial implications for regenerative engineering.

Carnosine inhibits glioblastoma growth independent from PI3K/Akt/mTOR signaling

Glioblastoma is a high-grade glioma with poor prognosis even after surgery and standard therapy. Here, we asked whether carnosine (β-alanyl-L-histidine), a naturally occurring dipeptide, exert its anti-neoplastic effect on glioblastoma cells via PI3K/Akt/mTOR signaling. Therefore, glioblastoma cells from the lines U87 and T98G were exposed to carnosine, to the mTOR inhibitor rapamycin and to the PI3K inhibitor Ly-294,002. Pyruvate dehydrogenase kinase (PDK4) expression, known to be a target of PI3K/Akt/mTOR, and which is also affected by carnosine, was analyzed by RT-qPCR, and reporter gene assays with the human PDK4 promoter were performed. Cell viability was assessed by cell-based assays and mTOR and Akt phosphorylation by Western blotting. Rapamycin and Ly-294,002 increased PDK4 mRNA expression in both cell lines but significance was only reached in U87. Carnosine significantly increased expression in both lines. A significant combinatorial effect of carnosine was only detected in U87 when the dipeptide was combined with Ly-294,002. Reporter gene assays revealed no specific effect of carnosine on the human PDK4 promoter, whereas both inhibitors increased reporter gene expression. Rapamycin reduced phosphorylation of mTOR, and Ly-294,002 that of Akt. A significant reduction of Akt phosphorylation was observed in the presence of carnosine in U87 but not in T98G, and carnosine had no effect on mTOR phosphorylation. Cell viability as determined by ATP in cell lysates was reduced only in the presence of carnosine. We conclude that carnosine’s anti-neoplastic effect is independent from PI3K/Akt/mTOR signaling. As the dipeptide reduced viability in tumor cells that do not respond to PI3K or mTOR inhibitors, it appears to be worth to further investigate the mechanisms by which carnosine exerts its anti-tumor effect and to consider it for therapy, especially as it is a naturally occurring compound that has already been used for the treatment of other diseases without indication of side-effects.

Thioredoxin-1 improves the immunometabolic phenotype of antitumor T cells

Adoptive transfer of tumor epitope-reactive T cells has emerged as a promising strategy to control tumor growth. However, chronically-stimulated T cells expanded for adoptive cell transfer are susceptible to cell death in an oxidative tumor microenvironment. Because oxidation of cell-surface thiols also alters protein functionality, we hypothesized that increasing the levels of thioredoxin (Trx), an antioxidant molecule facilitating reduction of proteins through cysteine thiol-disulfide exchange, in T cells will promote their sustained antitumor function. Using pre-melanosome protein (Pmel)-Trx1 transgenic mouse-derived splenic T cells, flow cytometry, and gene expression analysis, we observed here that higher Trx expression inversely correlated with reactive oxygen species and susceptibility to T-cell receptor restimulation or oxidation-mediated cell death. These Trx1-overexpressing T cells exhibited a cluster of differentiation 62L^hi (CD62L^hi) central memory-like phenotype with reduced glucose uptake (2-NBDG^lo) and decreased effector function (interferon γ^lo). Furthermore, culturing tumor-reactive T cells in the presence of recombinant Trx increased the dependence of T cells on mitochondrial metabolism and improved tumor control. We conclude that strategies for increasing the antioxidant capacity of antitumor T cells modulate their immunometabolic phenotype leading to improved immunotherapeutic control of established tumors.

Glutamine Addiction and Therapeutic Strategies in Lung Cancer

Lung cancer cells are well-documented to rewire their metabolism and energy production networks to support rapid survival and proliferation. This metabolic reorganization has been recognized as a hallmark of cancer. The increased uptake of glucose and the increased activity of the glycolytic pathway have been extensively described. However, over the past years, increasing evidence has shown that lung cancer cells also require glutamine to fulfill their metabolic needs. As a nitrogen source, glutamine contributes directly (or indirectly upon conversion to glutamate) to many anabolic processes in cancer, such as the biosynthesis of amino acids, nucleobases, and hexosamines. It plays also an important role in the redox homeostasis, and last but not least, upon conversion to α-ketoglutarate, glutamine is an energy and anaplerotic carbon source that replenishes tricarboxylic acid cycle intermediates. The latter is generally indicated as glutaminolysis. In this review, we explore the role of glutamine metabolism in lung cancer. Because lung cancer is the leading cause of cancer death with limited curative treatment options, we focus on the potential therapeutic approaches targeting the glutamine metabolism in cancer.

Global metabolite profiling analysis of lipotoxicity in HER2/neu-positive breast cancer cells

Recent work has shown that HER2/neu-positive breast cancer cells rely on a unique Warburg-like metabolism for survival and aggressive behavior. These cells are dependent on fatty acid (FA) synthesis, show markedly increased levels of stored fats and disruption of the synthetic process results in apoptosis. In this study, we used global metabolite profiling and a multi-omics network analysis approach to model the metabolic changes in this physiology under palmitate-supplemented growth conditions to gain insights into the molecular mechanism and its relevance to disease prevention and treatment. Computational analyses were used to define pathway enrichment based on the dataset of significantly altered metabolites and to integrate metabolomics and transcriptomics data in a multi-omics network analysis. Network-predicted changes and functional relationships were tested with cell assays in vitro. Palmitate-supplemented growth conditions induce distinct metabolic alterations. Growth of HER2-normal MCF7 cells is unaffected under these conditions whereas HER2/neu-positive cells display unchanged neutral lipid content, AMPK activation, inhibition of fatty acid synthesis and significantly altered glutamine, glucose and serine/glycine metabolism. The predominant upregulated lipid species is the novel bioactive lipid N-palmitoylglycine, which is non-toxic to these cells. Limiting the availability of glutamine significantly ameliorates the lipotoxic effects of palmitate, reduces CHOP and XBP1(s) induction and restores the expression levels of HER2 and HER3. The study shows that HER2/neu-positive breast cancer cells change their metabolic phenotype in the presence of palmitate. Palmitate induces AMPK activation and inhibition of fatty acid synthesis that feeds back into glycolysis as well as anaplerotic glutamine metabolism.

Sialic Acid Metabolism: A Key Player in Breast Cancer Metastasis Revealed by Metabolomics

Metastatic breast cancer is currently incurable. It has recently emerged that different metabolic pathways support metastatic breast cancer. To further uncover metabolic pathways enabling breast cancer metastasis, we investigated metabolic differences in mouse tumors of differing metastatic propensities using mass spectrometry-based metabolomics. We found that sialic acid metabolism is upregulated in highly metastatic breast tumors. Knocking out a key gene in sialic acid metabolism, Cmas, inhibits synthesis of the activated form of sialic acid, cytidine monophosphate-sialic acid and decreases the formation of lung metastases in vivo. Thus, the sialic acid pathway may be a new target against metastatic breast cancer.

Citrate chemistry and biology for biomaterials design

Leveraging the multifunctional nature of citrate in chemistry and inspired by its important role in biological tissues, a class of highly versatile and functional citrate-based materials (CBBs) has been developed via facile and cost-effective polycondensation. CBBs exhibiting tunable mechanical properties and degradation rates, together with excellent biocompatibility and processability, have been successfully applied in vitro and in vivo for applications ranging from soft to hard tissue regeneration, as well as for nanomedicine designs. We summarize in the review, chemistry considerations for CBBs design to tune polymer properties and to introduce functionality with a focus on the most recent advances, biological functions of citrate in native tissues with the new notion of degradation products as cell modulator highlighted, and the applications of CBBs in wound healing, nanomedicine, orthopedic, cardiovascular, nerve and bladder tissue engineering. Given the expansive evidence for citrate's potential in biology and biomaterial science outlined in this review, it is expected that citrate based materials will continue to play an important role in regenerative engineering.

Rewiring of Glutamine Metabolism Is a Bioenergetic Adaptation of Human Cells with Mitochondrial DNA Mutations

Using molecular, biochemical, and untargeted stable isotope tracing approaches, we identify a previously unappreciated glutamine-derived α-ketoglutarate (αKG) energy-generating anaplerotic flux to be critical in mitochondrial DNA (mtDNA) mutant cells that harbor human disease-associated oxidative phosphorylation defects. Stimulating this flux with αKG supplementation enables the survival of diverse mtDNA mutant cells under otherwise lethal obligatory oxidative conditions. Strikingly, we demonstrate that when residual mitochondrial respiration in mtDNA mutant cells exceeds 45% of control levels, αKG oxidative flux prevails over reductive carboxylation. Furthermore, in a mouse model of mitochondrial myopathy, we show that increased oxidative αKG flux in muscle arises from enhanced alanine synthesis and release into blood, concomitant with accelerated amino acid catabolism from protein breakdown. Importantly, in this mouse model of mitochondriopathy, muscle amino acid imbalance is normalized by αKG supplementation. Taken together, our findings provide a rationale for αKG supplementation as a therapeutic strategy for mitochondrial myopathies.

Acetyl-CoA promotes glioblastoma cell adhesion and migration through Ca2+-NFAT signaling

Here, Lee et al. investigated the molecular mechanisms by which acetyl-CoA production impacts gene expression and how acetyl-CoA promotes malignant phenotypes. Their findings show that acetyl-CoA can enhance H3K27ac in a locus-specific manner and that expression of cell adhesion genes is driven by acetyl-CoA in part through activation of Ca²⁺–NFAT signaling.

The metabolite acetyl-coenzyme A (acetyl-CoA) is the required acetyl donor for lysine acetylation and thereby links metabolism, signaling, and epigenetics. Nutrient availability alters acetyl-CoA levels in cancer cells, correlating with changes in global histone acetylation and gene expression. However, the specific molecular mechanisms through which acetyl-CoA production impacts gene expression and its functional roles in promoting malignant phenotypes are poorly understood. Here, using histone H3 Lys27 acetylation (H3K27ac) ChIP-seq (chromatin immunoprecipitation [ChIP] coupled with next-generation sequencing) with normalization to an exogenous reference genome (ChIP-Rx), we found that changes in acetyl-CoA abundance trigger site-specific regulation of H3K27ac, correlating with gene expression as opposed to uniformly modulating this mark at all genes. Genes involved in integrin signaling and cell adhesion were identified as acetyl-CoA-responsive in glioblastoma cells, and we demonstrate that ATP citrate lyase (ACLY)-dependent acetyl-CoA production promotes cell migration and adhesion to the extracellular matrix. Mechanistically, the transcription factor NFAT1 (nuclear factor of activated T cells 1) was found to mediate acetyl-CoA-dependent gene regulation and cell adhesion. This occurs through modulation of Ca²⁺ signals, triggering NFAT1 nuclear translocation when acetyl-CoA is abundant. The findings of this study thus establish that acetyl-CoA impacts H3K27ac at specific loci, correlating with gene expression, and that expression of cell adhesion genes are driven by acetyl-CoA in part through activation of Ca²⁺–NFAT signaling.

Reverse engineering the cancer metabolic network using flux analysis to understand drivers of human disease

Metabolic dysfunction has reemerged as an essential hallmark of tumorigenesis, and metabolic phenotypes are increasingly being integrated into pre-clinical models of disease. The complexity of these metabolic networks requires systems-level interrogation, and metabolic flux analysis (MFA) with stable isotope tracing present a suitable conceptual framework for such systems. Here we review efforts to elucidate mechanisms through which metabolism influences tumor growth and survival, with an emphasis on applications using stable isotope tracing and MFA. Through these approaches researchers can now quantify pathway fluxes in various in vitro and in vivo contexts to provide mechanistic insights at molecular and physiological scales respectively. Knowledge and discoveries in cancer models are paving the way toward applications in other biological contexts and disease models. In turn, MFA approaches will increasingly help to uncover new therapeutic opportunities that enhance human health.

Inhibition of O-GlcNAc transferase activity reprograms prostate cancer cell metabolism

Metabolic networks are highly connected and complex, but a single enzyme, O-GlcNAc transferase (OGT) can sense the availability of metabolites and also modify target proteins. We show that inhibition of OGT activity inhibits the proliferation of prostate cancer cells, leads to sustained loss of c-MYC and suppresses the expression of CDK1, elevated expression of which predicts prostate cancer recurrence (p=0.00179). Metabolic profiling revealed decreased glucose consumption and lactate production after OGT inhibition. This decreased glycolytic activity specifically sensitized prostate cancer cells, but not cells representing normal prostate epithelium, to inhibitors of oxidative phosphorylation (rotenone and metformin). Intra-cellular alanine was depleted upon OGT inhibitor treatment. OGT inhibitor increased the expression and activity of alanine aminotransferase (GPT2), an enzyme that can be targeted with a clinically approved drug, cycloserine. Simultaneous inhibition of OGT and GPT2 inhibited cell viability and growth rate, and additionally activated a cell death response. These combinatorial effects were predominantly seen in prostate cancer cells, but not in a cell-line derived from normal prostate epithelium. Combinatorial treatments were confirmed with two inhibitors against both OGT and GPT2. Taken together, here we report the reprogramming of energy metabolism upon inhibition of OGT activity, and identify synergistically lethal combinations that are prostate cancer cell specific.

Eugenol inhibits oxidative phosphorylation and fatty acid oxidation via downregulation of c-Myc/PGC-1β/ERRα signaling pathway in MCF10A-ras cells

Alteration in cellular energy metabolism plays a critical role in the development and progression of cancer. Targeting metabolic pathways for cancer treatment has been investigated as potential preventive or therapeutic methods. Eugenol (Eu), a major volatile constituent of clove essential oil mainly obtained from Syzygium, has been reported as a potential chemopreventive drug. However, the mechanism by which Eu regulates cellular energy metabolism is still not well defined. This study was designed to determine the effect of Eu on cellular energy metabolism during early cancer progression employing untransformed and H-ras oncogene transfected MCF10A human breast epithelial cells. Eu showed dose-dependent selective cytotoxicity toward MCF10A-ras cells but exhibited no apparent cytotoxicity in MCF10A cells. Treatment with Eu also significantly reduced intracellular ATP levels in MCF10A-ras cells but not in MCF10A cells. This effect was mediated mainly through inhibiting oxidative phosphorylation (OXPHOS) complexs and the expression of fatty acid oxidation (FAO) proteins including PPARα, MCAD and CPT1C by downregulating c-Myc/PGC-1β/ERRα pathway and decreasing oxidative stress in MCF10A-ras cells. These results indicate a novel mechanism involving the regulation of cellular energy metabolism by which Eu may prevent breast cancer progression.

Lactate dehydrogenase-A is indispensable for vascular smooth muscle cell proliferation and migration

The proliferation and migration of vascular smooth muscle cells (VSMCs) have been implicated in the pathogenesis of atherosclerosis. Increased aerobic glycolysis is a key feature of cellular phenotypes including cancer and immune cells. However, the role of aerobic glycolysis in the atherogenic phenotype of VSMCs remains largely unknown. Here, we investigated the role of lactate dehydrogenase-A (LDHA), which is a key enzyme for glycolysis, in the proliferation and migration of VSMCs. Activation of primary rat VSMCs with fetal bovine serum (FBS) or platelet-derived growth factor (PDGF) increased their proliferation and migration, glycolytic activity, and expression of LDHA. Wound healing and transwell migration assays demonstrated that small interfering RNA-mediated knockdown of LDHA and pharmacological inhibition of LDHA by oxamate both effectively inhibited VSMC proliferation and migration. Inhibition of LDHA activity by oxamate reduced PDGF-stimulated glucose uptake, lactate production, and ATP production. Taken together, this study shows that enhanced glycolysis in PDGF- or FBS-stimulated VSMCs plays an important role in their proliferation and migration and suggests that LDHA is a potential therapeutic target to prevent vessel lumen constriction during the course of atherosclerosis and restenosis.

The distinct metabolic phenotype of lung squamous cell carcinoma defines selective vulnerability to glycolytic inhibition

Adenocarcinoma (ADC) and squamous cell carcinoma (SqCC) are the two predominant subtypes of non-small cell lung cancer (NSCLC) and are distinct in their histological, molecular and clinical presentation. However, metabolic signatures specific to individual NSCLC subtypes remain unknown. Here, we perform an integrative analysis of human NSCLC tumour samples, patient-derived xenografts, murine model of NSCLC, NSCLC cell lines and The Cancer Genome Atlas (TCGA) and reveal a markedly elevated expression of the GLUT1 glucose transporter in lung SqCC, which augments glucose uptake and glycolytic flux. We show that a critical reliance on glycolysis renders lung SqCC vulnerable to glycolytic inhibition, while lung ADC exhibits significant glucose independence. Clinically, elevated GLUT1-mediated glycolysis in lung SqCC strongly correlates with high ¹⁸F-FDG uptake and poor prognosis. This previously undescribed metabolic heterogeneity of NSCLC subtypes implicates significant potential for the development of diagnostic, prognostic and targeted therapeutic strategies for lung SqCC, a cancer for which existing therapeutic options are clinically insufficient.

Adenocarcinoma and squamous cell carcinoma are distinct subtypes of non-small cell lung cancer. Here, the authors show that increased glycolytic flux, via increased glucose transporter Glut1 expression, is a core metabolic feature of squamous cell carcinoma that renders it sensitive to glycolysis inhibition.

A sensitive mass spectrometry platform identifies metabolic changes of life history traits in C. elegans

Abnormal nutrient metabolism is a hallmark of aging, and the underlying genetic and nutritional framework is rapidly being uncovered, particularly using C. elegans as a model. However, the direct metabolic consequences of perturbations in life history of C. elegans remain to be clarified. Based on recent advances in the metabolomics field, we optimized and validated a sensitive mass spectrometry (MS) platform for identification of major metabolite classes in worms and applied it to study age and diet related changes. Using this platform that allowed detection of over 600 metabolites in a sample of 2500 worms, we observed marked changes in fatty acids, amino acids and phospholipids during worm life history, which were independent from the germ-line. Worms underwent a striking shift in lipid metabolism after early adulthood that was at least partly controlled by the metabolic regulator AAK-2/AMPK. Most amino acids peaked during development, except aspartic acid and glycine, which accumulated in aged worms. Dietary intervention also influenced worm metabolite profiles and the regulation was highly specific depending on the metabolite class. Altogether, these MS-based methods are powerful tools to perform worm metabolomics for aging and metabolism-oriented studies.

Serum depletion induces changes in protein expression in the trophoblast-derived cell line HTR-8/SVneo

BACKGROUND

How nutrition and growth factor restriction due to serum depletion affect trophoblast function remains poorly understood. We performed a proteomic differential study of the effects of serum depletion on a first trimester human immortalized trophoblast cell line.

METHODS

The viability of HTR-8/SVneo trophoblast cells in culture with 0, 0.5 and 10 % fetal bovine serum (FBS) were assayed via MTT at 24, 48 and 64 h. A comparative proteomic analysis of the cells grown with those FBS levels for 24 h was performed using two-dimensional electrophoresis (2DE), followed by mass spectrometry for protein spot identification, and a database search and bioinformatics analysis of the expressed proteins. Differential spots were identified using the Kolmogorov-Smirnov test (n = 3, significance level 0.10, D > 0.642) and/or ANOVA (n = 3, p < 0.05).

RESULTS

The results showed that low serum doses or serum depletion differentially affect cell growth and protein expression. Differential expression was seen in 25 % of the protein spots grown with 0.5 % FBS and in 84 % of those grown with 0 % FBS, using 10 % serum as the physiological control. In 0.5 % FBS, this difference was related with biological processes typically affected by the serum, such as cell cycle, regulation of apoptosis and proliferation. In addition to these changes, in the serum-depleted proteome we observed downregulation of keratin 8, and upregulation of vimentin, the glycolytic enzymes enolase and pyruvate kinase (PKM2) and tumor progression-related inosine-5'-monophosphate dehydrogenase 2 (IMPDH2) enzyme. The proteins regulated by total serum depletion, but not affected by growth in 0.5 % serum, are members of the glycolytic and nucleotide metabolic pathways and the epithelial-to-mesenchymal transition (EMT), suggesting an adaptive switch characteristic of malignant cells.

CONCLUSIONS

This comparative proteomic analysis and the identified proteins are the first evidence of a protein expression response to serum depletion in a trophoblast cell model. Our results show that serum depletion induces specific changes in protein expression concordant with main cell metabolic adaptations and EMT, resembling the progression to a malignant phenotype.

Metabolic requirements for cancer cell proliferation

Background

The study of cancer metabolism has been largely dedicated to exploring the hypothesis that oncogenic transformation rewires cellular metabolism to sustain elevated rates of growth and division. Intense examination of tumors and cancer cell lines has confirmed that many cancer-associated metabolic phenotypes allow robust growth and survival; however, little attention has been given to explicitly identifying the biochemical requirements for cell proliferation in a rigorous manner in the context of cancer metabolism.

Results

Using a well-studied hybridoma line as a model, we comprehensively and quantitatively enumerate the metabolic requirements for generating new biomass in mammalian cells; this indicated a large biosynthetic requirement for ATP, NADPH, NAD⁺, acetyl-CoA, and amino acids. Extension of this approach to serine/glycine and glutamine metabolic pathways suggested lower limits on serine and glycine catabolism to supply one-carbon unit synthesis and significant availability of glutamine-derived carbon for biosynthesis resulting from nitrogen demands alone, respectively. We integrated our biomass composition results into a flux balance analysis model, placing upper bounds on mitochondrial NADH oxidation to simulate metformin treatment; these simulations reproduced several empirically observed metabolic phenotypes, including increased reductive isocitrate dehydrogenase flux.

Conclusions

Our analysis clarifies the differential needs for central carbon metabolism precursors, glutamine-derived nitrogen, and cofactors such as ATP, NADPH, and NAD⁺, while also providing justification for various extracellular nutrient uptake behaviors observed in tumors. Collectively, these results demonstrate how stoichiometric considerations alone can successfully predict empirically observed phenotypes and provide insight into biochemical dynamics that underlie responses to metabolic perturbations.

Electronic supplementary material

The online version of this article (doi:10.1186/s40170-016-0156-6) contains supplementary material, which is available to authorized users.