Phosphoglycerate mutase 1 coordinates glycolysis and biosynthesis to promote tumor growth

High-Resolution Crystal Structure of Muscle Phosphoglycerate Mutase Provides Insight into Its Nuclear Import and Role

Phosphoglycerate mutase (PGAM) is a glycolytic enzyme converting 3-phosphoglycerate to 2-phosphoglycerate, which in mammalian cells is expressed in two isoforms: brain (PGAM1) and muscle (PGAM2). Recently, it was shown that besides its enzymatic function, PGAM2 can be imported to the cell nucleus where it co-localizes with the nucleoli. It was suggested that it functions there to stabilize the nucleolar structure, maintain mRNA expression, and assist in the assembly of new pre-ribosomal subunits. However, the precise mechanism by which the protein translocates to the nucleus is unknown. In this study, we present the first crystal structure of PGAM2, identify the residues involved in the nuclear localization of the protein and propose that PGAM contains a “quaternary nuclear localization sequence (NLS)”, i.e., one that consists of residues from different protein chains. Additionally, we identify potential interaction partners for PGAM2 in the nucleoli and demonstrate that 14-3-3ζ/δ is indeed an interaction partner of PGAM2 in the nucleus. We also present evidence that the insulin/IGF1–PI3K–Akt–mTOR signaling pathway is responsible for the nuclear localization of PGAM2.

Targeting Glucose Metabolism Enzymes in Cancer Treatment: Current and Emerging Strategies

Simple Summary

Reprogramming of glucose metabolism is a hallmark of cancer and can be targeted by therapeutic agents. Some metabolism regulators, such as ivosidenib and enasidenib, have been approved for cancer treatment. Currently, more advanced and effective glucose metabolism enzyme-targeted anticancer drugs have been developed. Furthermore, some natural products have shown efficacy in killing tumor cells by regulating glucose metabolism, offering novel therapeutic opportunities in cancer. However, most of them have failed to be translated into clinical applications due to low selectivity, high toxicity, and side effects. Recent studies suggest that combining glucose metabolism modulators with chemotherapeutic drugs, immunotherapeutic drugs, and other conventional anticancer drugs may be a future direction for cancer treatment.

Abstract

Reprogramming of glucose metabolism provides sufficient energy and raw materials for the proliferation, metastasis, and immune escape of cancer cells, which is enabled by glucose metabolism-related enzymes that are abundantly expressed in a broad range of cancers. Therefore, targeting glucose metabolism enzymes has emerged as a promising strategy for anticancer drug development. Although several glucose metabolism modulators have been approved for cancer treatment in recent years, some limitations exist, such as a short half-life, poor solubility, and numerous adverse effects. With the rapid development of medicinal chemicals, more advanced and effective glucose metabolism enzyme-targeted anticancer drugs have been developed. Additionally, several studies have found that some natural products can suppress cancer progression by regulating glucose metabolism enzymes. In this review, we summarize the mechanisms underlying the reprogramming of glucose metabolism and present enzymes that could serve as therapeutic targets. In addition, we systematically review the existing drugs targeting glucose metabolism enzymes, including small-molecule modulators and natural products. Finally, the opportunities and challenges for glucose metabolism enzyme-targeted anticancer drugs are also discussed. In conclusion, combining glucose metabolism modulators with conventional anticancer drugs may be a promising cancer treatment strategy.

TGF-β signaling in the tumor metabolic microenvironment and targeted therapies

Transforming growth factor-β (TGF-β) signaling has a paradoxical role in cancer progression, and it acts as a tumor suppressor in the early stages but a tumor promoter in the late stages of cancer. Once cancer cells are generated, TGF-β signaling is responsible for the orchestration of the immunosuppressive tumor microenvironment (TME) and supports cancer growth, invasion, metastasis, recurrence, and therapy resistance. These progressive behaviors are driven by an “engine” of the metabolic reprogramming in cancer. Recent studies have revealed that TGF-β signaling regulates cancer metabolic reprogramming and is a metabolic driver in the tumor metabolic microenvironment (TMME). Intriguingly, TGF-β ligands act as an “endocrine” cytokine and influence host metabolism. Therefore, having insight into the role of TGF-β signaling in the TMME is instrumental for acknowledging its wide range of effects and designing new cancer treatment strategies. Herein, we try to illustrate the concise definition of TMME based on the published literature. Then, we review the metabolic reprogramming in the TMME and elaborate on the contribution of TGF-β to metabolic rewiring at the cellular (intracellular), tissular (intercellular), and organismal (cancer-host) levels. Furthermore, we propose three potential applications of targeting TGF-β-dependent mechanism reprogramming, paving the way for TGF-β-related antitumor therapy from the perspective of metabolism.

The Long and the Short of It: NEAT1 and Cancer Cell Metabolism

Simple Summary

Altered metabolism is a hallmark of most cancers. The way that cancer cells regulate their energy production to fuel constant proliferation has been of interest with the hope that it may be exploited therapeutically. The long noncoding RNA, NEAT1, is often dysregulated in tumours. NEAT1 RNA can be transcribed as two isoforms with different lengths, with each variant responsible for different functions. This review explores how the isoforms contribute to cancer metabolism.

Abstract

The long noncoding RNA NEAT1 is known to be heavily dysregulated in many cancers. A single exon gene produces two isoforms, NEAT1_1 and NEAT1_2, through alternative 3′-end processing. As the longer isoform, NEAT1_2 is an essential scaffold for nuclear paraspeckle formation. It was previously thought that the short NEAT1_1 isoform only exists to keep the NEAT1 locus active for rapid paraspeckle formation. However, a recent glycolysis-enhancing function for NEAT1_1, contributing to cancer cell proliferation and the Warburg effect, has been demonstrated. Previous studies have mainly focused on quantifying total NEAT1 and NEAT1_2 expression levels. However, in light of the NEAT1_1 role in cancer cell metabolism, the contribution from specific NEAT1 isoforms is no longer clear. Here, the roles of NEAT1_1 and NEAT1_2 in metabolism and cancer progression are discussed.

Revisited Metabolic Control and Reprogramming Cancers by Means of the Warburg Effect in Tumor Cells

Aerobic glycolysis is an emerging hallmark of many human cancers, as cancer cells are defined as a “metabolically abnormal system”. Carbohydrates are metabolically reprogrammed by its metabolizing and catabolizing enzymes in such abnormal cancer cells. Normal cells acquire their energy from oxidative phosphorylation, while cancer cells acquire their energy from oxidative glycolysis, known as the “Warburg effect”. Energy–metabolic differences are easily found in the growth, invasion, immune escape and anti-tumor drug resistance of cancer cells. The glycolysis pathway is carried out in multiple enzymatic steps and yields two pyruvate molecules from one glucose (Glc) molecule by orchestral reaction of enzymes. Uncontrolled glycolysis or abnormally activated glycolysis is easily observed in the metabolism of cancer cells with enhanced levels of glycolytic proteins and enzymatic activities. In the “Warburg effect”, tumor cells utilize energy supplied from lactic acid-based fermentative glycolysis operated by glycolysis-specific enzymes of hexokinase (HK), keto-HK-A, Glc-6-phosphate isomerase, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase, phosphofructokinase (PFK), phosphor-Glc isomerase (PGI), fructose-bisphosphate aldolase, phosphoglycerate (PG) kinase (PGK)1, triose phosphate isomerase, PG mutase (PGAM), glyceraldehyde-3-phosphate dehydrogenase, enolase, pyruvate kinase isozyme type M2 (PKM2), pyruvate dehydrogenase (PDH), PDH kinase and lactate dehydrogenase. They are related to glycolytic flux. The key enzymes involved in glycolysis are directly linked to oncogenesis and drug resistance. Among the metabolic enzymes, PKM2, PGK1, HK, keto-HK-A and nucleoside diphosphate kinase also have protein kinase activities. Because glycolysis-generated energy is not enough, the cancer cell-favored glycolysis to produce low ATP level seems to be non-efficient for cancer growth and self-protection. Thus, the Warburg effect is still an attractive phenomenon to understand the metabolic glycolysis favored in cancer. If the basic properties of the Warburg effect, including genetic mutations and signaling shifts are considered, anti-cancer therapeutic targets can be raised. Specific therapeutics targeting metabolic enzymes in aerobic glycolysis and hypoxic microenvironments have been developed to kill tumor cells. The present review deals with the tumor-specific Warburg effect with the revisited viewpoint of recent progress.

Selective Ablation of Sod2 in Astrocytes Induces Sex-Specific Effects on Cognitive Function, d-Serine Availability, and Astrogliosis

Cognitive decline is a debilitating aspect of aging and neurodegenerative diseases such as Alzheimer's disease are closely associated with mitochondrial dysfunction, increased reactive oxygen species, neuroinflammation, and astrogliosis. This study investigated the effects of decreased mitochondrial antioxidant response specifically in astrocytes on cognitive performance and neuronal function in C57BL/6J mice using a tamoxifen-inducible astrocyte-specific knockout of manganese superoxide dismutase (aSOD2-KO), a mitochondrial matrix antioxidant that detoxifies superoxide generated during mitochondrial respiration. We reduced astrocyte SOD2 levels in male and female mice at 11-12 months of age and tested in an automated home cage (PhenoTyper) apparatus for diurnal patterns, spatial learning, and memory function at 15 months of age. aSOD2-KO impaired hippocampal-dependent spatial working memory and decreased cognitive flexibility in the reversal phase of the testing paradigm in males. Female aSOD2-KO showed no learning and memory deficits compared with age-matched controls despite significant reduction in hippocampal SOD2 expression. aSOD2-KO males further showed decreased hippocampal long-term potentiation, but paired-pulse facilitation was unaffected. Levels of d-serine, an NMDA receptor coagonist, were also reduced in aSOD2-KO mice, but female knockouts showed a compensatory increase in serine racemase expression. Furthermore, aSOD2-KO mice demonstrated increased density of astrocytes, indicative of astrogliosis, in the hippocampus compared with age-matched controls. These data demonstrate that reduction in mitochondrial antioxidant stress response in astrocytes recapitulates age-related deficits in cognitive function, d-serine availability, and astrogliosis. Therefore, improving astrocyte mitochondrial homeostasis may provide a therapeutic target for intervention for cognitive impairment in aging.SIGNIFICANCE STATEMENT Diminished antioxidant response is associated with increased astrogliosis in aging and in Alzheimer's disease. Manganese superoxide dismutase (SOD2) is an antioxidant in the mitochondrial matrix that detoxifies superoxide and maintains mitochondrial homeostasis. We show that astrocytic ablation of SOD2 impairs hippocampal-dependent plasticity in spatial working memory, reduces long-term potentiation of hippocampal neurons and levels of the neuromodulator d-serine, and increases astrogliosis, consistent with defects in advanced aging and Alzheimer's disease. Our data provide strong evidence for sex-specific effects of astrocytic SOD2 functions in age-related cognitive dysfunction.

Comparative analysis of transient receptor potential channel 5 opposite strand-induced gene expression patterns and protein-protein interactions in triple-negative breast cancer

In patients with triple-negative breast cancer (TNBC), high tumour mutation burden and aberrant oncogene expression profiles are some of the causes of poor prognosis. Therefore, it is necessary to identify aberrantly expressed oncogenes, since they have the potential to serve as therapeutic targets. Transient receptor potential channel 5 opposite strand (TRPC5OS) has been previously shown to function as a novel tumour inducer. However, the underlying mechanism of TRPC5OS function in TNBC remain to be elucidated. Therefore, in the present study TRPC5OS expression was first measured in tissue samples of patients with TNBC and a panel of breast cancer cell lines (ZR-75-1, MDA-MB-453, SK-BR-3, JIMT-1, BT474 and HCC1937) by using qRT-PCR and Western blotting. Subsequently, the possible effects of TRPC5OS on MDA-MB-231 cells proliferation were determined using Cell Counting Kit-8 and 5-Ethynyl-2′-deoxyuridine assays after Lentiviral transfection of MDA-MB-231. In addition, potential interaction partners of TRPC5OS were explored using liquid chromatography-mass spectrometry (LC-MS)/MS. Gene expression patterns following TRPC5OS overexpression were also detected in MDA-MB-231 cells by using High-throughput sequencing. Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) analysis were then used to systematically verify the potential interactions among the TRPC5OS-regulated genes. The potential relationship between TRPC5OS-interacting proteins and gene expression patterns were studied using Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) analysis. TRPC5OS expression was found to be significantly higher in TNBC tumour tissues and breast cancer cell lines compared with luminal tumour tissues and ZR-75-1. In addition, the overexpression of TRPC5OS significantly increased cell proliferation. High-throughput sequencing results revealed that 5,256 genes exhibited differential expression following TRPC5OS overexpression, including 3,269 upregulated genes and 1,987 downregulated genes. GO analysis results indicated that the functions of these differentially expressed genes were enriched in the categories of ‘cell division’ and ‘cell proliferation’ regulation. KEGG analysis showed that the TRPC5OS-regulated genes were associated with processes of ‘homologous recombination’ and ‘TNF signalling pathways’. Subsequently, 17 TRPC5OS-interacting proteins were found using LC-MS/MS and STRING analysis. The most important protein among interacting proteins was ENO1 which was associated with glycolysis and regulated proliferation of cancer. In summary, data from the present study suggest that TRPC5OS overexpression can increase TNBC cell proliferation and ENO1 may be a potential target protein mediated by TRPC5OS. Therefore, TRPC5OS may serve as a novel therapeutic target for TNBC.

Emerging roles of fatty acid metabolism in cancer and their targeted drug development

Metabolic reprogramming is now considered as one of hallmark of tumor cells and provides them with a selective survival/growth advantage to resist harsh micro-environmental stress. Fatty acid (FA) metabolism of tumor cells supports the biosynthetic needs and provides fuel sources for energy supply. Since FA metabolic reprogramming is a critical link in tumor metabolism, its various roles in tumors have attracted increasing interest. Herein, we review the mechanisms through which cancer cells rewire their FA metabolism with a focus on the pathway of FA metabolism and its targeting drug development. The failure and successful cases of targeting tumor FA metabolism are expected to bypass the metabolic vulnerability and improve the efficacy of targeted therapy.

Emerging strategies to overcome resistance to third-generation EGFR inhibitors

Epidermal growth factor receptor (EGFR), the receptor for members of the epidermal growth factor family, regulates cell proliferation and signal transduction; moreover, EGFR is related to the inhibition of tumor cell proliferation, angiogenesis, invasion, metastasis, and apoptosis. Therefore, EGFR has become an important target for the treatment of cancer, including non-small cell lung cancer, head and neck cancer, breast cancer, glioma, cervical cancer, and bladder cancer. First- to third-generation EGFR inhibitors have shown considerable efficacy and have significantly improved disease prognosis. However, most patients develop drug resistance after treatment. The challenge of overcoming intrinsic and acquired resistance in primary and recurrent cancer mediated by EGFR mutations is thus driving the search for alternative strategies in the design of new therapeutic agents. In view of resistance to third-generation inhibitors, understanding the intricate mechanisms of resistance will offer insight for the development of more advanced targeted therapies. In this review, we discuss the molecular mechanisms of resistance to third-generation EGFR inhibitors and review recent strategies for overcoming resistance, new challenges, and future development directions.

Ubiquitin-modified proteome analysis of Eriocheir sinensis hemocytes during Spiroplasma eriocheiris infection

Spiroplasma eriocheiris, the pathogen of Eriocheir sinensis tremor disease (TD), has bring a huge economic loss to China aquaculture. The hemocytes of crab as the first target cells of S. eriocheiris, but the interactive relationship between the E. sinensis and this pathogen not particularly clear. The present study is the first time to analysis the role of protein ubiquitination in the process of E. sinensis hemocytes response S. eriocheiris infection. By applying label-free quantitative liquid chromatography with tandem mass spectrometry proteomics, 950 lysine ubiquitination sites and 803 ubiquitination peptides on 458 proteins were identified, of which 48 ubiquitination sites on 40 proteins were quantified as significantly changed after the S. eriocheiris infection. Bioinformatics analysis of ubiquitination different proteins suggested many biological process and pathways were participated in the interaction between S. eriocheiris and host cell, such as ubiquitin system, endocytosis, prophenoloxidase system (proPO system), cell apoptosis, glycolysis. Our study can enhance our understanding of interaction between the crab and S. eriocheiris, and also provides basis to study the role of protein ubiquitination in other crustacean innate immune system.

Expression Patterns of Energy-Related Genes in Single Cells Uncover Key Isoforms and Enzymes That Gain Priority Under Nanoparticle-Induced Stress

Cellular responses to nanoparticles (NPs) have been largely studied in cell populations, providing averaged values that often misrepresent the true molecular processes that occur in the individual cell. To understand how a cell redistributes limited molecular resources to achieve optimal response and survival requires single-cell analysis. Here we applied multiplex single molecule-based fluorescence in situ hybridization (fliFISH) to quantify the expression of 10 genes simultaneously in individual intact cells, including glycolysis and glucose transporter genes, which are critical for restoring and maintaining energy balance. We focused on individual gill epithelial cell responses to lithium cobalt oxide (LCO) NPs, which are actively pursued as cathode materials in lithium-ion batteries, raising concerns about their impact on the environment and human health. We found large variabilities in the expression levels of all genes between neighboring cells under the same exposure conditions, from only a few transcripts to over 100 copies in individual cells. Gene expression ratios among the 10 genes in each cell uncovered shifts in favor of genes that play key roles in restoring and maintaining energy balance. Among these genes are isoforms that can secure and increase glycolysis rates more efficiently, as well as genes with multiple cellular functions, in addition to glycolysis, including DNA repair, regulation of gene expression, cell cycle progression, and proliferation. Our study uncovered prioritization of gene expression in individual cells for restoring energy balance under LCO NP exposures. Broadly, our study gained insight into single-cell strategies for redistributing limited resources to achieve optimal response and survival under stress.

Differing impact of phosphoglycerate mutase 1-deficiency on brown and white adipose tissue

Brown adipose tissue (BAT) is a metabolically active organ that contributes to the thermogenic response to cold exposure. In addition, other thermogenic cells termed beige adipocytes are generated in white adipose tissue (WAT) by cold exposure. Although activation of brown/beige adipose tissue is associated with mobilization of both glucose and lipids, few studies have focused on the role of glycolytic enzymes in regulating adipose tissue function. We generated mouse models with specific deletion of the glycolytic enzyme phosphoglycerate mutase 1 (PGAM1) from adipose tissue. Deletion of Pgam1 from both BAT and WAT promoted whitening of BAT with beiging of visceral WAT, whereas deletion of Pgam1 from BAT alone led to whitening of BAT without beiging of WAT. Our results demonstrate a potential role of glycolytic enzymes in beiging of visceral WAT and suggest that PGAM1 would be a novel therapeutic target in obesity and diabetes.

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Pgam1 deletion leads to whitening of brown adipose tissue

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Pgam1 deletion promotes beiging of visceral white adipose tissue (WAT)

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Pgam1 deletion-induced beiging is associated with increased levels of amino acids

Targeting Energy Metabolism in Cancer Treatment

Cancer is the second most common cause of death worldwide after cardiovascular diseases. The development of molecular and biochemical techniques has expanded the knowledge of changes occurring in specific metabolic pathways of cancer cells. Increased aerobic glycolysis, the promotion of anaplerotic responses, and especially the dependence of cells on glutamine and fatty acid metabolism have become subjects of study. Despite many cancer treatment strategies, many patients with neoplastic diseases cannot be completely cured due to the development of resistance in cancer cells to currently used therapeutic approaches. It is now becoming a priority to develop new treatment strategies that are highly effective and have few side effects. In this review, we present the current knowledge of the enzymes involved in the different steps of glycolysis, the Krebs cycle, and the pentose phosphate pathway, and possible targeted therapies. The review also focuses on presenting the differences between cancer cells and normal cells in terms of metabolic phenotype. Knowledge of cancer cell metabolism is constantly evolving, and further research is needed to develop new strategies for anti-cancer therapies.

Targeting allosteric regulation of cancer metabolism

Metabolic reprogramming is observed across all cancer types. Indeed, the success of many classic chemotherapies stems from their targeting of cancer metabolism. Contemporary research in this area has refined our understanding of tumor-specific metabolic mechanisms and has revealed strategies for exploiting these vulnerabilities selectively. Based on this growing understanding, new small-molecule tools and drugs have been developed to study and target tumor metabolism. Here, we highlight allosteric modulation of metabolic enzymes as an attractive mechanism of action for small molecules that target metabolic enzymes. We then discuss the mechanistic insights garnered from their application in cancer studies and highlight the achievements of this approach in targeting cancer metabolism. Finally, we discuss technological advances in drug discovery for allosteric modulators of enzyme activity.

Modulation of PKM1/2 levels by steric blocking morpholinos alters the metabolic and pluripotent state of murine pluripotent stem cells

Cellular metabolism plays both an active and passive role in embryonic development, pluripotency, and cell-fate decisions. However, little is known regarding the role of metabolism in regulating the recently described "formative" pluripotent state. The pluripotent developmental continuum features a metabolic switch from a bivalent metabolism (both glycolysis and oxidative phosphorylation) in naïve cells, to predominantly glycolysis in primed cells. We investigated the role of pyruvate kinase muscle isoforms (PKM1/2) in naïve, formative, and primed mouse embryonic stem cells through modulation of PKM1/2 mRNA transcripts using steric blocking morpholinos that downregulate PKM2 and upregulate PKM1. We have examined these effects in naïve, formative, and primed cells by quantifying the effects of PKM1/2 modulation on pluripotent and metabolic transcripts and by measuring shifts in the population frequencies of cells expressing naïve and primed cell surface markers by flow cytometry. Our results demonstrate that modulating PKM1 and PKM2 levels alters the transition from the naïve state into a primed pluripotent state by enhancing the proportion of the affected cells seen in the "formative" state. Therefore, we conclude that PKM1/2 actively contributes to mechanisms that oversee early stem pluripotency and their progression towards a primed pluripotent state.

6-Phosphogluconate dehydrogenase and its crystal structures

6-Phosphogluconate dehydrogenase (6PGDH; EC 1.1.1.44) catalyses the oxidative decarboxylation of 6-phosphogluconate to ribulose 5-phosphate in the context of the oxidative part of the pentose phosphate pathway. Depending on the species, it can be a homodimer or a homotetramer. Oligomerization plays a functional role not only because the active site is at the interface between subunits but also due to the interlocking tail-modulating activity, similar to that of isocitrate dehydrogenase and malic enzyme, which catalyse a similar type of reaction. Since the pioneering crystal structure of sheep liver 6PGDH, which allowed motifs common to the β-hydroxyacid dehydrogenase superfamily to be recognized, several other 6PGDH crystal structures have been solved, including those of ternary complexes. These showed that more than one conformation exists, as had been suggested for many years from enzyme studies in solution. It is inferred that an asymmetrical conformation with a rearrangement of one of the two subunits underlies the homotropic cooperativity. There has been particular interest in the presence or absence of sulfate during crystallization. This might be related to the fact that this ion, which is a competitive inhibitor that binds in the active site, can induce the same 6PGDH configuration as in the complexes with physiological ligands. Mutagenesis, inhibitors, kinetic and binding studies, post-translational modifications and research on the enzyme in cancer cells have been complementary to the crystallographic studies. Computational modelling and new structural studies will probably help to refine the understanding of the functioning of this enzyme, which represents a promising therapeutic target in immunity, cancer and infective diseases. 6PGDH also has applied-science potential as a biosensor or a biobattery. To this end, the enzyme has been efficiently immobilized on specific polymers and nanoparticles. This review spans the 6PGDH literature and all of the 6PGDH crystal structure data files held by the Protein Data Bank.

The tetrameric structure of Plasmodium falciparum phosphoglycerate mutase is critical for optimal enzymatic activity

The glycolytic enzyme phosphoglycerate mutase (PGM) is of utmost importance for overall cellular metabolism and has emerged as a novel therapeutic target in cancer cells. This enzyme is also conserved in the rapidly proliferating malarial parasite Plasmodium falciparum, which have a similar metabolic framework as cancer cells and rely on glycolysis as the sole energy-yielding process during intraerythrocytic development. There is no redundancy among the annotated PGM enzymes in Plasmodium, and PfPGM1 is absolutely required for the parasite survival as evidenced by conditional knockdown in our study. A detailed comparison of PfPGM1 with its counterparts followed by in-depth structure-function analysis revealed unique attributes of this parasitic protein. Here, we report for the first time the importance of oligomerization for the optimal functioning of the enzyme in vivo, as earlier studies in eukaryotes only focused on the effects in vitro. We show that single point mutation of the amino acid residue W68 led to complete loss of tetramerization and diminished catalytic activity in vitro. Additionally, ectopic expression of the WT PfPGM1 protein enhanced parasite growth, whereas the monomeric form of PfPGM1 failed to provide growth advantage. Furthermore, mutation of the evolutionarily conserved residue K100 led to a drastic reduction in enzymatic activity. The indispensable nature of this parasite enzyme highlights the potential of PfPGM1 as a therapeutic target against malaria, and targeting the interfacial residues critical for oligomerization can serve as a focal point for promising drug development strategies that may not be restricted to malaria only.

The long noncoding RNA glycoLINC assembles a lower glycolytic metabolon to promote glycolysis

Non-covalent complexes of glycolytic enzymes, called metabolons, were postulated in the 1970s, but the concept has been controversial. Here we show that a c-Myc-responsive long noncoding RNA (lncRNA) that we call glycoLINC (gLINC) acts as a backbone for metabolon formation between all four glycolytic payoff phase enzymes (PGK1, PGAM1, ENO1, and PKM2) along with lactate dehydrogenase A (LDHA). The gLINC metabolon enhances glycolytic flux, increases ATP production, and enables cell survival under serine deprivation. Furthermore, gLINC overexpression in cancer cells promotes xenograft growth in mice fed a diet deprived of serine, suggesting that cancer cells employ gLINC during metabolic reprogramming. We propose that gLINC makes a functional contribution to cancer cell adaptation and provide the first example of a lncRNA-facilitated metabolon.

Metabolic dysregulation and emerging therapeutical targets for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an aggressive human cancer with increasing incidence worldwide. Multiple efforts have been made to explore pharmaceutical therapies to treat HCC, such as targeted tyrosine kinase inhibitors, immune based therapies and combination of chemotherapy. However, limitations exist in current strategies including chemoresistance for instance. Tumor initiation and progression is driven by reprogramming of metabolism, in particular during HCC development. Recently, metabolic associated fatty liver disease (MAFLD), a reappraisal of new nomenclature for non-alcoholic fatty liver disease (NAFLD), indicates growing appreciation of metabolism in the pathogenesis of liver disease, including HCC, thereby suggesting new strategies by targeting abnormal metabolism for HCC treatment. In this review, we introduce directions by highlighting the metabolic targets in glucose, fatty acid, amino acid and glutamine metabolism, which are suitable for HCC pharmaceutical intervention. We also summarize and discuss current pharmaceutical agents and studies targeting deregulated metabolism during HCC treatment. Furthermore, opportunities and challenges in the discovery and development of HCC therapy targeting metabolism are discussed.

Mannose enhances the radio-sensitivity of esophageal squamous cell carcinoma with low MPI expression by suppressing glycolysis

BACKGROUND

To investigate the effect of mannose on radio-sensitivity of human esophageal squamous cell carcinoma (ESCC) cell line and its possible mechanism.

METHODS

The expression of mannose phosphate isomerase (MPI) in human esophageal cancer cell lines were detected by Western blot. The inhibitory effect of mannose on human esophageal cancer cell lines were observed by MTT assay. Plate clone formation assay was performed to investigate the efficacy of mannose on radio-sensitivity of human esophageal cancer cells. The apoptosis rates of tumor cells treated with mannose and/or radiation therapy was calculated by flow cytometry. Furthermore, we analyzed intracellular metabolites using liquid chromatography mass spectrometry to identify selective sugar metabolites.

RESULTS

MPI expression was various in human esophageal cancer cells. KYSE70 cells was associated with the highest MPI expression whereas KYSE450 cells had the lowest MPI expression level. When administrated with 11.1 mM/L mannose, the same inhibitory effect was observed in both KYSE70 and KYSE450 cell lines. Moreover, the inhibitory effect was significant on KYSE450 cell lines with an increased mannose concentration. The application of 11.1 mM/L mannose could significantly enhance the radio-sensitivity of KYSE450 cell line; and tumor cell apoptosis rate was also increased. However, there was limited efficacy of mannose on the radio-sensitivity and apoptosis rate of KYSE70 cell line. Additionally, intracellular metabolites analyzation revealed that glycolysis could be disturbed by mannose when combined with radiation therapy in esophageal cancer cells.

CONCLUSION

In esophageal cancer cell lines with low MPI expression, the administration of mannose was associated with enhanced radio-sensitivity.

Tissue differences in the exosomal/small extracellular vesicle proteome and their potential as indicators of altered tissue metabolism

Exosomes/small extracellular vesicles (sEVs) can serve as multifactorial mediators of cell-to-cell communication through their miRNA and protein cargo. Quantitative proteomic analysis of five cell lines representing metabolically important tissues reveals that each cell type has a unique sEV proteome. While classical sEV markers such as CD9/CD63/CD81 vary markedly in abundance, we identify six sEV markers (ENO1, GPI, HSPA5, YWHAB, CSF1R, and CNTN1) that are similarly abundant in sEVs of all cell types. In addition, each cell type has specific sEV markers. Using fat-specific Dicer-knockout mice with decreased white adipose tissue and increased brown adipose tissue, we show that these cell-type-specific markers can predict the changing origin of the serum sEVs. These results provide a valuable resource for understanding the sEV proteome of the cells and tissues important in metabolic homeostasis, identify unique sEV markers, and demonstrate how these markers can help in predicting the tissue of origin of serum sEVs.

By performing comparative proteomics, Garcia-Martin et al. identify markers common to exosomes/sEVs from multiple cell types, as well as markers unique to each cell type. Using a lipodystrophy mouse model, they demonstrate the use of this sEV proteome dataset to predict the tissue of origin of circulating exosomes/sEVs in vivo.

Obesity and adipose tissue impact on T-cell response and cancer immune checkpoint blockade therapy

Many different types of cancer are now well known to have increased occurrence or severity in individuals with obesity. The influence of obesity on cancer and the immune cells in the tumor microenvironment has been thought to be a pleiotropic effect. As key endocrine and immune organs, the highly plastic adipose tissues play crucial roles in obesity pathophysiology, as they show alterations according to environmental cues. Adipose tissues of lean subjects present mostly anti-inflammatory cells that are crucial in tissue remodeling, favoring uncoupling protein 1 expression and non-shivering thermogenesis. Oppositely, obese adipose tissues display massive proinflammatory immune cell infiltration, dying adipocytes, and enhanced crown-like structure formation. In this review, we discuss how obesity can lead to derangements and dysfunctions in antitumor CD8+ T lymphocytes dysfunction. Moreover, we explain how obesity can affect the efficiency of cancer immunotherapy, depicting the mechanisms involved in this process. Cancer immunotherapy management includes monoclonal antibodies targeting the immune checkpoint blockade. Exhausted CD8+ T lymphocytes show elevated programmed cell death-1 (PD-1) expression and highly glycolytic tumors tend to show a good response to anti-PD-1/PD-L1 immunotherapy. Although obesity is a risk factor for the development of several neoplasms and is linked with increased tumor growth and aggressiveness, obesity is also related to improved response to cancer immunotherapy, a phenomenon called the obesity paradox. However, patients affected by obesity present higher incidences of adverse events related to this therapy. These limitations highlight the necessity of a deeper investigation of factors that influence the obesity paradox to improve the application of these therapies.

Metabolic shift to serine biosynthesis through 3-PG accumulation and PHGDH induction promotes tumor growth in pancreatic cancer

Cancer cells craftily adapt their energy metabolism to their microenvironment. Nutrient deprivation due to hypovascularity and fibrosis is a major characteristic of pancreatic ductal adenocarcinoma (PDAC); thus, PDAC cells must produce energy intrinsically. However, the enhancement of energy production via activating Kras mutations is insufficient to explain the metabolic rewiring of PDAC cells. Here, we investigated the molecular mechanism underlying the metabolic shift in PDAC cells under serine starvation. Amino acid analysis revealed that the concentrations of all essential amino acids and most nonessential amino acids were decreased in the blood of PDAC patients. In addition, the plasma serine concentration was significantly higher in PDAC patients with PHGDH-high tumors than in those with PHGDH-low tumors. Although the growth and tumorigenesis of PK-59 cells with PHGDH promoter hypermethylation were significantly decreased by serine starvation, these activities were maintained in PDAC cell lines with PHGDH promoter hypomethylation by serine biosynthesis through PHGDH induction. In fact, DNA methylation analysis by pyrosequencing revealed that the methylation status of the PHGDH promoter was inversely correlated with the PHGDH expression level in human PDAC tissues. In addition to PHGDH induction by serine starvation, PDAC cells showed enhanced serine biosynthesis under serine starvation through 3-PG accumulation via PGAM1 knockdown, resulting in enhanced PDAC cell growth and tumor growth. However, PHGDH knockdown efficiently suppressed PDAC cell growth and tumor growth under serine starvation. These findings provide evidence that targeting the serine biosynthesis pathway by inhibiting PHGDH is a potent therapeutic approach to eliminate PDAC cells in nutrient-deprived microenvironments.

Protein expression of the tear film of domestic cats before and after inoculation with Toxoplasma gondii

BACKGROUND

Tear film (TF) helps maintain and protect ocular function against damage to the ocular surface. Proteins are one of its main constituents, whose expression pattern can be used as a biomarker of ocular changes and systemic diseases. The aim of this study was to evaluate the expression of proteins in the TF of domestic cats before and after infection with Toxoplasma gondii, in the phases of acute infection and chronicity. Twelve healthy cats received orally homogenized brain matter obtained from mice inoculated with T. gondii oocysts, strain ME49. Cat feces were collected daily from the third day after infection to assess the release of oocysts. TF samples were obtained from cats, by Schirmer's Tear Test 1, on day 0 (before infection), day 5 after infection (acute phase of infection, with maximum peak release of oocysts in feces) and on day 21 after infection (start of chronic phase, 7 days after total absence of oocyst release in feces). Tear samples were also submitted to proteomic analysis in a Q-Tof-Premier mass spectrometer.

RESULTS

A total of 37 proteins with scores equal to or greater than 100 were identified on D0, followed by 36 on D5 and 42 on D21. Of these, 27 were common to D0 and D5, 33 to D0 and D21, 27 to D5 and D21, and 26 were common to the three groups, totaling 54 proteins. The most abundant proteins were lipocalin allergen Fel d, serum albumin, aldehyde dehydrogenase, lactoperoxidase and lactotransferrin. There was no significant difference in the abundance of proteins found on D0 and D5, but there was a statistical difference between D0 and D21 for ACT1_AEDAE, CERU_HUMAN and GELS_HUMAN. Regarding D5 and D21, there were significant differences for KV1_CANLF, LAC_PIG, TRFL_PIG, ACT1_AEDAE, CERU_HUMAN, GELS_HUMAN and OVOS2_HUMAN.

CONCLUSIONS

The main proteins identified in the TF of domestic cats are similar to those found in humans and other animal species. Most are part of the ocular surface defense system against injuries. The most expressed proteins in animals in the chronic phase of T. gondii infection are associated with the immune response to the parasite.

3D-QSAR, Molecular Docking, and MD Simulations of Anthraquinone Derivatives as PGAM1 Inhibitors

PGAM1 is overexpressed in a wide range of cancers, thereby promoting cancer cell proliferation and tumor growth, so it is gradually becoming an attractive target. Recently, a series of inhibitors with various structures targeting PGAM1 have been reported, particularly anthraquinone derivatives. In present study, the structure–activity relationships and binding mode of a series of anthraquinone derivatives were probed using three-dimensional quantitative structure–activity relationships (3D-QSAR), molecular docking, and molecular dynamics (MD) simulations. Comparative molecular field analysis (CoMFA, r² = 0.97, q² = 0.81) and comparative molecular similarity indices analysis (CoMSIA, r² = 0.96, q² = 0.82) techniques were performed to produce 3D-QSAR models, which demonstrated satisfactory results, especially for the good predictive abilities. In addition, molecular dynamics (MD) simulations technology was employed to understand the key residues and the dominated interaction between PGAM1 and inhibitors. The decomposition of binding free energy indicated that the residues of F22, K100, V112, W115, and R116 play a vital role during the ligand binding process. The hydrogen bond analysis showed that R90, W115, and R116 form stable hydrogen bonds with PGAM1 inhibitors. Based on the above results, 7 anthraquinone compounds were designed and exhibited the expected predictive activity. The study explored the structure–activity relationships of anthraquinone compounds through 3D-QSAR and molecular dynamics simulations and provided theoretical guidance for the rational design of new anthraquinone derivatives as PGAM1 inhibitors.

NEAT1 is essential for metabolic changes that promote breast cancer growth and metastasis

Accelerated glycolysis is the main metabolic change observed in cancer, but the underlying molecular mechanisms and their role in cancer progression remain poorly understood. Here, we show that the deletion of the long noncoding RNA (lncRNA) Neat1 in MMTV-PyVT mice profoundly impairs tumor initiation, growth, and metastasis, specifically switching off the penultimate step of glycolysis. Mechanistically, NEAT1 directly binds and forms a scaffold bridge for the assembly of PGK1/PGAM1/ENO1 complexes and thereby promotes substrate channeling for high and efficient glycolysis. Notably, NEAT1 is upregulated in cancer patients and correlates with high levels of these complexes, and genetic and pharmacological blockade of penultimate glycolysis ablates NEAT1-dependent tumorigenesis. Finally, we demonstrate that Pinin mediates glucose-stimulated nuclear export of NEAT1, through which it exerts isoform-specific and paraspeckle-independent functions. These findings establish a direct role for NEAT1 in regulating tumor metabolism, provide new insights into the Warburg effect, and identify potential targets for therapy.

Elevated ATGL in colon cancer cells and cancer stem cells promotes metabolic and tumorigenic reprogramming reinforced by obesity

Obesity is a worldwide epidemic associated with increased risk and progression of colon cancer. Here, we aimed to determine the role of adipose triglyceride lipase (ATGL), responsible for intracellular lipid droplet (LD) utilization, in obesity-driven colonic tumorigenesis. In local colon cancer patients, significantly increased ATGL levels in tumor tissue, compared to controls, were augmented in obese individuals. Elevated ATGL levels in human colon cancer cells (CCC) relative to non-transformed were augmented by an obesity mediator, oleic acid (OA). In CCC and colonospheres, enriched in colon cancer stem cells (CCSC), inhibition of ATGL prevented LDs utilization and inhibited OA-stimulated growth through retinoblastoma-mediated cell cycle arrest. Further, transcriptomic analysis of CCC, with inhibited ATGL, revealed targeted pathways driving tumorigenesis, and high-fat-diet obesity facilitated tumorigenic pathways. Inhibition of ATGL in colonospheres revealed targeted pathways in human colonic tumor crypt base cells (enriched in CCSC) derived from colon cancer patients. In CCC and colonospheres, we validated selected transcripts targeted by ATGL inhibition, some with emerging roles in colonic tumorigeneses (ATG2B, PCK2, PGAM1, SPTLC2, IGFBP1, and ABCC3) and others with established roles (MYC and MUC2). These findings demonstrate obesity-promoted, ATGL-mediated colonic tumorigenesis and establish the therapeutic significance of ATGL in obesity-reinforced colon cancer progression.

The Pentose Phosphate Pathway in Cancer: Regulation and Therapeutic Opportunities

BACKGROUND

Tumorigenesis is associated with deregulation of nutritional requirements, intermediary metabolites production, and microenvironment interactions. Unlike their normal cell counterparts, tumor cells rely on aerobic glycolysis, through the Warburg effect.

SUMMARY

The pentose phosphate pathway (PPP) is a major glucose metabolic shunt that is upregulated in cancer cells. The PPP comprises an oxidative and a nonoxidative phase and is essential for nucleotide synthesis of rapidly dividing cells. The PPP also generates nicotinamide adenine dinucleotide phosphate, which is required for reductive metabolism and to counteract oxidative stress in tumor cells. This article reviews the regulation of the PPP and discusses inhibitors that target its main pathways. Key Message: Exploiting the metabolic vulnerability of the PPP offers potential novel therapeutic opportunities and improves patients' response to cancer therapy.

Profiling Carbohydrate Metabolism in Liver and Hepatocellular Carcinoma with [13C]-Glycerate Probes

The interplay between glycolysis and gluconeogenesis is central to carbohydrate metabolism. Here, we describe novel methods to assess carbohydrate metabolism using [¹³C]-probes derived from glycerate, a molecule whose metabolic fate in mammals remains underexplored. Isotope-based studies were conducted via NMR and mass spectrometry analyses of freeze-clamped liver tissue extracts after [2,3-¹³C₂]glycerate infusion. The ex vivo investigations were correlated with in vivo measurements using hyperpolarized [1-¹³C]glycerate. Application of [¹³C]glycerate to N-nitrosodiethylamine (DEN)-treated rats provided further assessments of intermediary carbohydrate metabolism in hepatocellular carcinoma. This method afforded direct analyses of control versus DEN tissues, and altered ratios of ¹³C metabolic products as well as unique glycolysis intermediates were observed in the DEN liver/tumor. Isotopomer studies showed increased glycerate uptake and altered carbohydrate metabolism in the DEN rats.

Tumor microenvironment-activated cancer cell membrane-liposome hybrid nanoparticle-mediated synergistic metabolic therapy and chemotherapy for non-small cell lung cancer

BACKGROUND

Biomimetic nanotechnology-based RNA interference (RNAi) has been successful in improving theranostic efficacy in malignant tumors. Its integration with hybrid biomimetic membranes made of natural cell membranes fused with liposomal membranes is mutually beneficial and extends their biofunctions. However, limited research has focused on engineering such biomimetics to endow them with unique properties and functions, in particular, those essential for a "smart" drug delivery system, such as a tumor microenvironment (TME)-activated multifunctional biomimetic nanoplatform.

RESULTS

Herein, we utilized an integrated hybrid nanovesicle composed of cancer cell membranes (Cm) and matrix metallopeptidase 9 (MMP-9)-switchable peptide-based charge-reversal liposome membranes (Lipm) to coat lipoic acid-modified polypeptides (LC) co-loaded with phosphoglycerate mutase 1 (PGAM1) siRNA (siPGAM1) and DTX. The nanovesicle presented a negatively charged coating (citraconic anhydride-grafted poly-L-lysine, PC) in the middle layer for pH-triggered charge conversion functionalization. The established chemotherapeutic drug (DTX) co-delivery system CLip-PC@CO-LC nanoparticles (NPs) have a particle size of ~ 193 nm and present the same surface proteins as the Cm. Confocal microscopy and flow cytometry results indicated a greater uptake of MMP-9-treated CLip-PC@CO-LC NPs compared with that of the CLip-PC@CO-LC NPs without MMP-9 pretreatment. The exposure to MMP-9 activated positively charged cell-penetrating peptides on the surface of the hybrid nanovesicles. Moreover, pH triggered membrane disruption, and redox triggered DTX and siRNA release, leading to highly potent target-gene silencing in glycolysis and chemotherapy with enhanced antiproliferation ability. The biodistribution results demonstrated that the CLip-PC@LC-DiR NPs accumulated in the tumor owing to a combination of long blood retention time, homologous targeting ability, and TME-activated characteristics. The CLip-PC@CO-LC NPs led to more effective tumor growth inhibition than the DTX and free siPGAM1 formulations.

CONCLUSIONS

TME-activated cancer cell membrane-liposome integrated hybrid NPs provide an encouraging nanoplatform that combines RNAi with chemotherapy for precise treatment of non-small cell lung cancer.

Moonlighting functions of metabolic enzymes and metabolites in cancer

The growing field of tumor metabolism has greatly expanded our knowledge of metabolic reprogramming in cancer. Apart from their established roles, various metabolic enzymes and metabolites harbor non-canonical ("moonlighting") functions to support malignant transformation. In this article, we intend to review the current understanding of moonlighting functions of metabolic enzymes and related metabolites broadly existing in cancer cells by dissecting each major metabolic pathway and its regulation of cellular behaviors. Understanding these non-canonical functions may broaden the horizon of the cancer metabolism field and uncover novel therapeutic vulnerabilities in cancer.

The nexus between redox state and intermediary metabolism

Reactive oxygen species (ROS) are not just a by-product of cellular metabolic processes but act as signalling molecules that regulate both physiological and pathophysiological processes. A close connection exists in cells between redox homeostasis and cellular metabolism. In this review, we describe how intracellular redox state and glycolytic intermediary metabolism are closely coupled. On the one hand, ROS signalling can control glycolytic intermediary metabolism by direct regulation of the activity of key metabolic enzymes and indirect regulation via redox-sensitive transcription factors. On the other hand, metabolic adaptation and reprogramming in response to physiological or pathological stimuli regulate intracellular redox balance, through mechanisms such as the generation of reducing equivalents. We also discuss the impact of these intermediary metabolism-redox circuits in physiological and disease settings across different tissues. A better understanding of the mechanisms regulating these intermediary metabolism-redox circuits will be crucial to the development of novel therapeutic strategies.

More Than Meets the Eye Regarding Cancer Metabolism

In spite of the continuous improvement in our knowledge of the nature of cancer, the causes of its formation and the development of new treatment methods, our knowledge is still incomplete. A key issue is the difference in metabolism between normal and cancer cells. The features that distinguish cancer cells from normal cells are the increased proliferation and abnormal differentiation and maturation of these cells, which are due to regulatory changes in the emerging tumour. Normal cells use oxidative phosphorylation (OXPHOS) in the mitochondrion as a major source of energy during division. During OXPHOS, there are 36 ATP molecules produced from one molecule of glucose, in contrast to glycolysis which provides an ATP supply of only two molecules. Although aerobic glucose metabolism is more efficient, metabolism based on intensive glycolysis provides intermediate metabolites necessary for the synthesis of nucleic acids, proteins and lipids, which are in constant high demand due to the intense cell division in cancer. This is the main reason why the cancer cell does not "give up" on glycolysis despite the high demand for energy in the form of ATP. One of the evolving trends in the development of anti-cancer therapies is to exploit differences in the metabolism of normal cells and cancer cells. Currently constructed therapies, based on cell metabolism, focus on the attempt to reprogram the metabolic pathways of the cell in such a manner that it becomes possible to stop unrestrained proliferation.

Activated AMPK promoted the decrease of lactate production in rat Sertoli cells exposed to Zearalenone

Zearalenone, which is ubiquitous in grains and animal feed, is a mycotoxin that can cause serious damage to animals and humans. Sertoli cells (SCs) can be used to study ZEA male reproductive toxicity in vitro. SCs provide energy for germ cells, where AMPK regulates intracellular energy. In order to explore the regulatory effect of AMPK on ZEA-induced lactate decline, we activated AMPK by AICAR and then inhibited AMPK by Compound C with ZEA-treated SCs for 24 h to detect intracellular lactate production-related indicators. Cell viability in the presence of 20 μmol/L ZEA and either 50 μmol/L AICAR or 5 μmol/L Compound C, respectively, did not damage SCs, and could effectively either activate or inhibit AMPK. Inhibition of AMPK promoted the production of pyruvate and lactate via increased expression of the glycolysis-related genes Pgam1 and the lactate production-related proteins GLUT1, LDHA, and MCT4. Activating AMPK inhibited the production of lactate and pyruvate by suppressing the expression of glycolysis-related genes HK1, Pgam1, and Gpi1 and that of lactate production-related proteins LDHA and MCT4. Zearalenone destroys the energy balance in SCs, activates P-AMPK, which inhibit the production of lactate and pyruvate in SCs. This also leads to the decrease of energy supply of SCs to spermatogenic cells, damages to reproductive system.

The Crucial Roles of Intermediate Metabolites in Cancer

Metabolic alteration, one of the hallmarks of cancer cells, is important for cancer initiation and development. To support their rapid growth, cancer cells alter their metabolism so as to obtain the necessary energy and building blocks for biosynthetic pathways, as well as to adjust their redox balance. Once thought to be merely byproducts of metabolic pathways, intermediate metabolites are now known to mediate epigenetic modifications and protein post-transcriptional modifications (PTM), as well as connect cellular metabolism with signal transduction. Consequently, they can affect a myriad of processes, including proliferation, apoptosis, and immunity. In this review, we summarize multiple representative metabolites involved in glycolysis, the pentose phosphate pathway (PPP), the tricarboxylic acid (TCA) cycle, lipid synthesis, ketogenesis, methionine metabolism, glutamine metabolism, and tryptophan metabolism, focusing on their roles in chromatin and protein modifications and as signal-transducing messengers.

Metabolic determinants of B-cell selection

B-cells are antibody-producing cells of the adaptive immune system. Approximately 75% of all newly generated B-cells in the bone marrow are autoreactive and express potentially harmful autoantibodies. To prevent autoimmune disease, the immune system has evolved a powerful mechanism to eliminate autoreactive B-cells, termed negative B-cell selection. While designed to remove autoreactive clones during early B-cell development, our laboratory recently discovered that transformed B-cells in leukemia and lymphoma are also subject to negative selection. Indeed, besides the risk of developing autoimmune disease, B-cells are inherently prone to malignant transformation: to produce high-affinity antibodies, B-cells undergo multiple rounds of somatic immunoglobulin gene recombination and hypermutation. Reflecting high frequencies of DNA-breaks, adaptive immune protection by B-cells comes with a dramatically increased risk of development of leukemia and lymphoma. Of note, B-cells exist under conditions of chronic restriction of energy metabolism. Here we discuss how these metabolic gatekeeper functions during B-cell development provide a common mechanism for the removal of autoreactive and premalignant B-cells to safeguard against both autoimmune diseases and B-cell malignancies.

Enzymatic activation of pyruvate kinase increases cytosolic oxaloacetate to inhibit the Warburg effect

Pharmacological activation of the glycolytic enzyme PKM2 or expression of the constitutively active PKM1 isoform in cancer cells results in decreased lactate production, a phenomenon known as the PKM2 paradox in the Warburg effect. Here we show that oxaloacetate (OAA) is a competitive inhibitor of human lactate dehydrogenase A (LDHA) and that elevated PKM2 activity increases de novo synthesis of OAA through glutaminolysis, thereby inhibiting LDHA in cancer cells. We also show that replacement of human LDHA with rabbit LDHA, which is relatively resistant to OAA inhibition, eliminated the paradoxical correlation between the elevated PKM2 activity and the decreased lactate concentration in cancer cells treated with a PKM2 activator. Furthermore, rabbit LDHA-expressing tumours, compared to human LDHA-expressing tumours in mice, displayed resistance to the PKM2 activator. These findings describe a mechanistic explanation for the PKM2 paradox by showing that OAA accumulates and inhibits LDHA following PKM2 activation.

A Schistosoma japonicum MicroRNA Exerts Antitumor Effects Through Inhibition of Both Cell Migration and Angiogenesis by Targeting PGAM1

MicroRNA (miRNA) is an important regulator for gene expression. Recent studies showed that some heterogenous miRNAs derived from both parasite and plant can regulate expression of mammalian gene in a cross-species or even a cross-kingdom manner. Here, we identified a Schistosoma japonicum miRNA (designated as sja-miR-61) that is present in the hepatocyte of mice infected with the parasite. The sja-miR-61 mimics significantly inhibited the migration of both mouse and human hepatoma cells in vitro. In a xenograft animal model, significant reductions of the tumor volume and weight were observed in mice inoculated with hepatoma cells transfected with sja-miR-61 mimics compared to the controls. We found that the in vivo inhibition of tumor growth was through its anti-angiogenesis activity. Mechanically, we identified the phosphoglycerate mutase 1 (PGAM1) gene as a target of sja-miR-61 and found that the sja-miR-61-mediated suppression of cell migration and anti-angiogenesis by cross-species down-regulation of PGAM1 expression. These data indicated that sja-miR-61 is a tumor suppressor miRNA that may have therapeutic potential for human cancers.

Phytocompounds Targeting Metabolic Reprogramming in Cancer: An Assessment of Role, Mechanisms, Pathways, and Therapeutic Relevance

The metabolism of cancer is remarkably different from that of normal cells and confers a variety of benefits, including the promotion of other cancer hallmarks. As the rewired metabolism is a near-universal property of cancer cells, efforts are underway to exploit metabolic vulnerabilities for therapeutic benefits. In the continued search for safer and effective ways of cancer treatment, structurally diverse plant-based compounds have gained substantial attention. Here, we present an extensive assessment of the role of phytocompounds in modulating cancer metabolism and attempt to make a case for the use of plant-based compounds in targeting metabolic vulnerabilities of cancer. We discuss the pharmacological interactions of phytocompounds with major metabolic pathways and evaluate the role of phytocompounds in the regulation of growth signaling and transcriptional programs involved in the metabolic transformation of cancer. Lastly, we examine the potential of these compounds in the clinical management of cancer along with limitations and challenges.

In Silico Drug Screening Analysis against the Overexpression of PGAM1 Gene in Different Cancer Treatments

Phosphoglycerate mutase 1 (PGAM1) is considered as a novel target for multiple types of cancer drugs for the upregulation in tumor, cell prefoliation, and cell migration. During aerobic glycolysis, PGAM1 plays a critical role in cancer cell metabolism by catalyzing the conversion of 3-phosphoglycerate (3PG) to 2-phosphoglycerate (2PG). In this computational-based study, the molecular docking approach was used with the best binding active sites of PGAM1 to screen 5,000 Chinese medicinal phytochemical library. The docking results were three ligands with docking score, RMSD-refine, and residues. Docking scores were -16.57, -15.22, and -15.74. RMSD values were 0.87, 2.40, and 0.98, and binding site residues were Arg 191, Arg 191, Arg 116, Arg 90, Arg 10, and Tyr 92. The best compounds were subjected to ADMETsar, ProTox-2 server, and Molinspiration analysis to evaluate the toxicological and drug likeliness potential of such selected compounds. The UCSF-Chimera tool was used to visualize the results, which shows that the three medicinal compounds named N-Nitrosohexamethyleneimine, Subtrifloralactone-K, and Kanzonol-N in chain-A were successfully binding with the active pockets of PGAM1. The study might facilitate identifying the hit molecules that could be beneficial in the development of antidrugs against various types of cancer treatment. These hit phytochemicals could be beneficial for further investigation of a novel target for cancer.

Targeting Pyrimidine Metabolism in the Era of Precision Cancer Medicine

Metabolic rewiring is considered as a primary feature of cancer. Malignant cells reprogram metabolism pathway in response to various intrinsic and extrinsic drawback to fuel cell survival and growth. Among the complex metabolic pathways, pyrimidine biosynthesis is conserved in all living organism and is necessary to maintain cellular fundamental function (i.e. DNA and RNA biosynthesis). A wealth of evidence has demonstrated that dysfunction of pyrimidine metabolism is closely related to cancer progression and numerous drugs targeting pyrimidine metabolism have been approved for multiple types of cancer. However, the non-negligible side effects and limited efficacy warrants a better strategy for negating pyrimidine metabolism in cancer. In recent years, increased studies have evidenced the interplay of oncogenic signaling and pyrimidine synthesis in tumorigenesis. Here, we review the recent conceptual advances on pyrimidine metabolism, especially dihydroorotate dehydrogenase (DHODH), in the framework of precision oncology medicine and prospect how this would guide the development of new drug precisely targeting the pyrimidine metabolism in cancer.

Glucose Response by Stem Cell-Derived β Cells In Vitro Is Inhibited by a Bottleneck in Glycolysis

Stem cell-derived β (SC-β) cells could provide unlimited human β cells toward a curative diabetes treatment. Differentiation of SC-β cells yields transplantable islets that secrete insulin in response to glucose challenges. Following transplantation into mice, SC-β cell function is comparable to human islets, but the magnitude and consistency of response in vitro are less robust than observed in cadaveric islets. Here, we profile metabolism of SC-β cells and islets to quantify their capacity to sense glucose and identify reduced anaplerotic cycling in the mitochondria as the cause of reduced glucose-stimulated insulin secretion in SC-β cells. This activity can be rescued by challenging SC-β cells with intermediate metabolites from the TCA cycle and late but not early glycolysis, downstream of the enzymes glyceraldehyde 3-phosphate dehydrogenase and phosphoglycerate kinase. Bypassing this metabolic bottleneck results in a robust, bi-phasic insulin release in vitro that is identical in magnitude to functionally mature human islets.

Glucose-stimulated insulin secretion is deficient in stem cell-derived β (SC-β) cells in vitro. Davis et al. use metabolomic analysis to define a glycolytic bottleneck inhibiting glucose metabolism and sensing in SC-β cells. Cell-permeable intermediates bypass this bottleneck, as does transplantation in vivo, producing insulin secretion indistinguishable from human islets.

Roles of Ion Fluxes, Metabolism, and Redox Balance in Cancer Therapy

Recent Advances: The 2019 Nobel Prize awarded to the mechanisms for oxygen sensing and adaptation according to oxygen availability, highlighting the fundamental importance of gaseous molecules. Gaseous molecules, including reactive oxygen species (ROS), can interact with different cations generated during metabolic and redox dysregulation in cancer cells. Cross talk between calcium signaling and metabolic/redox pathways leads to network-based dyregulation in cancer. Significance: Recent discovery on using small molecules targeting the ion channels, redox signaling, and protein modification on metabolic enzymes can effectively inhibit cancer growth. Several FDA-approved drugs and clinical trials are ongoing to target the calcium channels, such as TRPV6 and TRPM8. Multiple small molecules from natural products target metablic and redox enzymes to exert an anticancer effect. Critical Issues: Small molecules targeting key ion channels, metabolic enzymes that control key aspects of metabolism, and redox proteins are promising, but their action mechanisms of the target are needed to be elucidated with advanced-omic technologies, which can give network-based and highly dimensioal data. In addition, small molecules that can directly modify the protein residues have emerged as a novel anticancer strategy. Future Directions: Advanced technology accelerates the detection of ions and metabolic and redox changes in clinical samples for diagnosis and informs the decision of cancer treatment. The improvement of ROS detection, ROS target identification, and computational-aid drug discovery also improves clincal outcome.Overall, network-based or holistic regulations of cancer via ion therapy and metabolic and redox intervention are promising as new anticancer strategies. Antioxid. Redox Signal. 34, 1108-1127.

Characterization of genetically modified mice for phosphoglycerate mutase, a vitally-essential enzyme in glycolysis

Glycolytic metabolism is closely involved in physiological homeostasis and pathophysiological states. Among glycolytic enzymes, phosphoglycerate mutase (PGAM) has been reported to exert certain physiological role in vitro, whereas its impact on glucose metabolism in vivo remains unclear. Here, we report the characterization of Pgam1 knockout mice. We observed that homozygous knockout mice of Pgam1 were embryonic lethal. Although we previously reported that both PGAM-1 and -2 affect global glycolytic profile of cancers in vitro, in vivo glucose parameters were less affected both in the heterozygous knockout of Pgam1 and in Pgam2 transgenic mice. Thus, the impact of PGAM on in vivo glucose metabolism is rather complex than expected before.

PGAM1 and TP53 mRNA levels in canine mammary carcinomas - Short communication

TP53 and PGAM1 genes play a key role in glycolysis which is an essential metabolic pathway of cancer cells for obtaining energy. The purpose of this work was to evaluate PGAM1 and TP53 mRNA expressions in canine mammary carcinomas (CMC) and to correlate them with animal data and tumour histological features. None of the nine samples analysed revealed PGAM1 DNA sequence variations. PGAM1 and TP53 RNA expressions from 21 CMC were analysed using a one-step reverse transcription-PCR kit and its platform system. Most CMC samples had low levels of PGAM1 mRNA (71.5%) and normal expression of TP53 mRNA (95.2%). Our results suggest a different feature of the Warburg effect on canine mammary cancer cells compared to human cells.

The Role of MicroRNAs in Lung Cancer Metabolism

MicroRNAs (miRNAs) are short-strand non-coding RNAs that are responsible for post-transcriptional regulation of many biological processes. Their differential expression is important in supporting tumorigenesis by causing dysregulation in normal biological functions including cell proliferation, apoptosis, metastasis and invasion and cellular metabolism. Cellular metabolic processes are a tightly regulated mechanism. However, cancer cells have adapted features to circumvent these regulations, recognizing metabolic reprogramming as an important hallmark of cancer. The miRNA expression profile may differ between localized lung cancers, advanced lung cancers and solid tumors, which lead to a varying extent of metabolic deregulation. Emerging evidence has shown the relationship between the differential expression of miRNAs with lung cancer metabolic reprogramming in perpetuating tumorigenesis. This review provides an insight into the role of different miRNAs in lung cancer metabolic reprogramming by targeting key enzymes, transporter proteins or regulatory components alongside metabolic signaling pathways. These discussions would allow a deeper understanding of the importance of miRNAs in tumor progression therefore providing new avenues for diagnostic, therapeutic and disease management applications.

EGFR mutation mediates resistance to EGFR tyrosine kinase inhibitors in NSCLC: From molecular mechanisms to clinical research

With the development of precision medicine, molecular targeted therapy has been widely used in the field of cancer, especially in non-small-cell lung cancer (NSCLC). Epidermal growth factor receptor (EGFR) is a well-recognized and effective target for NSCLC therapies, targeted EGFR therapy with EGFR-tyrosine kinase inhibitors (EGFR-TKIs) has achieved ideal clinical efficacy in recent years. Unfortunately, resistance to EGFR-TKIs inevitably occurs due to various mechanisms after a period of therapy. EGFR mutations, such as T790M and C797S, are the most common mechanism of EGFR-TKI resistance. Here, we discuss the mechanisms of EGFR-TKIs resistance induced by secondary EGFR mutations, highlight the development of targeted drugs to overcome EGFR mutation-mediated resistance, and predict the promising directions for development of novel candidates.