Asparagine couples mitochondrial respiration to ATF4 activity and tumor growth

Natural product as a lead for impairing mitochondrial respiration in cancer cells

The impact of the isoxazole derivative of usnic acid, ISOXUS (formerly known as 2b) on cancer and non-cancerous cell metabolism was investigated. ISOXUS significantly reduced the utilisation of most metabolic substrates that produce NADH or FADH2, mitochondrial electron flow and oxygen consumption rate (OCR) in MCF-7 breast cancer cells in contrast to HB2 normal epithelial cells. Molecular docking revealed that ISOXUS inhibits mitochondrial respiratory chain complex II, which was confirmed experimentally. Disturbance of electron flow in MCF-7 cells resulted in increased reactive oxygen species (ROS) production. They appeared crucial for ISOXUS-induced cancer cell vacuolization and a drop in survival as an antioxidant, α-tocopherol, protected against these processes. These findings indicate that ISOXUS is a metabolic inhibitor that targets mitochondrial complex II in breast cancer cells resulting in diminished ATP production and increased ROS formation which translates into reduced cell viability.

X-ray crystallographic and kinetic studies of biguanide containing aryl sulfonamides as carbonic anhydrase inhibitors

Here, we report a small series of dual-targeting compounds that combine the prototypical carbonic anhydrase (CA) zinc-binding sulfonamide moiety with the biguanide group of metformin, an emerging anticancer drug. The compounds reported similar in vitro inhibition profiles on a panel of physiologically relevant human (h)CAs, with marked selectivity for the cancer related IX and XII isoforms. The binding modes of representative inhibitors 5b and 5c within the active site of the hCA isoforms II and XII-mimic were assessed by X-ray crystallography, thus allowing us to clarify molecular features that may be useful for the design of more specific and potent inhibitors. For instance, we identified a mutation in the hCA XII-mimic which was found responsible for the selectivity of the ligands toward the tumor associated isoform. Interestingly, in the hCA II/5c complex, a second inhibitor molecule was bound to the catalytic cleft, probably affecting the inhibition properties of the canonical zinc-bound inhibitor.

Group A Streptococcal asparagine metabolism regulates bacterial virulence

Group A Streptococcus (GAS) causes various human diseases linked to virulome expression predominantly regulated by the two-component system (TCS), CovR/S. Here, we demonstrate that asparagine (Asn) presence in a minimal chemically defined medium increases virulence gene expression in a CovR-dependent fashion. It also decreases the transcription of asparagine synthetase (AsnA), the ABC transporter responsible for Asn uptake (GlnPQ), and that of the hemolysin toxins responsible for scavenging Asn from the host. Metabolomics data show that Asn availability increases intracellular ADP/ATP ratio, which enhances phosphatase activity in structurally related CovS sensors and is probably responsible for the Asn-mediated decrease in CovR phosphorylation. Mutants deficient in AsnA, GlnPQ, asparaginase, (AsnB) activities are attenuated in a mouse model of human GAS invasive soft tissue infection. The similarity between the mechanisms of Asn-mediated regulation of GAS virulence and tumor growth suggests that, as in cancer, components maintaining Asn homeostasis could be targeted for anti-GAS treatments.

Asparagine transporter supports macrophage inflammation via histone phosphorylation

Solute carrier (SLC) family is essential for immune responses; nevertheless, whether and how SLCs regulate macrophage inflammation remains unclear. Here, we demonstrate that K636 acetylation mediates high abundance of SLC6A14 in inflammatory macrophages. Notably, the pharmacological inhibition or genetic modulation of SLC6A14 reduces macrophage interleukin-1β (IL-1β) secretion dependently of lower asparagine uptake and subsequently enhanced nuclear LKB1. Mechanistically, nuclear LKB1 lessens MAPK pathway-mediated NLRP3 inflammasome activation by increased histone 3 S10/28 phosphorylation-dependent cyclin O transcription. Moreover, myeloid Slc6a14 deficiency alleviates pulmonary inflammation via suppressing inflammatory macrophage responses. Overall, these results uncover a network by which SLC6A14-mediated asparagine uptake orchestrates macrophage inflammation through histone phosphorylation, providing a crucial target for modulation of inflammatory diseases.

Inhibition of mitochondrial complex I induces mitochondrial ferroptosis by regulating CoQH2 levels in cancer

Ferroptosis, a novel form of regulated cell death induced by the excessive accumulation of lipid peroxidation products, plays a pivotal role in the suppression of tumorigenesis. Two prominent mitochondrial ferroptosis defense systems are glutathione peroxidase 4 (GPX4) and dihydroorotate dehydrogenase (DHODH), both of which are localized within the mitochondria. However, the existence of supplementary cellular defense mechanisms against mitochondrial ferroptosis remains unclear. Our findings unequivocally demonstrate that inactivation of mitochondrial respiratory chain complex I (MCI) induces lipid peroxidation and consequently invokes ferroptosis across GPX4 low-expression cancer cells. However, in GPX4 high expression cancer cells, the MCI inhibitor did not induce ferroptosis, but increased cell sensitivity to ferroptosis induced by the GPX4 inhibitor. Overexpression of the MCI alternative protein yeast NADH-ubiquinone reductase (NDI1) not only quells ferroptosis induced by MCI inhibitors but also confers cellular protection against ferroptosis inducers. Mechanically, MCI inhibitors actuate an elevation in the NADH level while concomitantly diminishing the CoQH2 level. The manifestation of MCI inhibitor-induced ferroptosis can be reversed by supplementation with mitochondrial-specific analogues of CoQH2. Notably, MCI operates in parallel with mitochondrial-localized GPX4 and DHODH to inhibit mitochondrial ferroptosis, but independently of cytosolically localized GPX4 or ferroptosis suppressor protein 1(FSP1). The MCI inhibitor IACS-010759, is endowed with the ability to induce ferroptosis while concurrently impeding tumor proliferation in vivo. Our results identified a ferroptosis defense mechanism mediated by MCI within the mitochondria and suggested a therapeutic strategy for targeting ferroptosis in cancer treatment.

Extracellular Vesicle-Packaged Linc-ZNF25-1 from Pancreatic Cancer Cell Promotes Pancreatic Stellate Cell Uptake of Asparagine to Advance Chemoresistance

Extensive fibrous stroma plays an important role in gemcitabine (GEM) resistance. However, the mechanism by which pancreatic cancer cells interact with pancreatic stellate cells (PSCs) to promote GEM resistance remains unclear. This study investigates the role of metabolic crosstalk between these two cells in inducing GEM resistance. Extracellular vesicles (EVs) of parental and GEM-resistant pancreatic cancer cells are extracted and performed metabolic assays and long noncoding RNA (lncRNA) sequencing. Pancreatic cancer cell-derived EVs promote PSCs activation and extracellular matrix formation, and GEM-resistant pancreatic cancer cells produce more asparagine (Asn), favoring PSCs activation. Mechanistically, pancreatic cancer cell-derived EVs mediate linc-ZNF25-1 to promote Asn uptake via the IGF2BP3/c-Myc/SLC1A5 pathway in PSCs. In addition, mouse models elucidate the oncogenic function of linc-ZNF25-1 and the enhanced therapeutic effect of asparaginase (L-ASNase) in combination with GEM in pancreatic cancer. This study demonstrates that pancreatic cancer cell-derived EVs promote the uptake of Asn released from pancreatic cancer cells through the upregulation of SLC1A5 in PSCs, facilitating PSCs activation and pancreatic cancer resistance to GEM. L-ASNase in combination with GEM is a potential therapeutic strategy for targeting stromal cells to enhance the efficacy of chemotherapeutic agents against pancreatic cancer.

Asparagine prevents intestinal stem cell aging via the autophagy-lysosomal pathway

The age-associated decline in intestinal stem cell (ISC) function is a key factor in intestinal aging in organisms, resulting in impaired intestinal function and increased susceptibility to age-related diseases. Consequently, it is imperative to develop effective therapeutic strategies to prevent ISC aging and functional decline. In this study, we utilized an aging Drosophila model screening of amino acids and found that asparagine (Asn), a nonessential amino acid in vivo, exhibits its profound anti-aging properties on ISCs. Asn inhibits the hyperproliferation of aging ISCs in Drosophila, maintains intestinal homeostasis, and extends the lifespan of aging flies. Complementarily, Asn promotes the growth and branching of elderly murine intestinal organoids, indicating its anti-aging capacity to enhance ISC function. Mechanistic analyses have revealed that Asn exerts its effects via the activation of the autophagic signaling pathway. In summary, this study has preliminarily explored the potential supportive role of Asn in ameliorating intestinal aging, providing a foundation for further research into therapeutic interventions targeting age-related intestinal dysfunction.

Xenotopic synthetic biology: Prospective tools for delaying aging and age-related diseases

Metabolic dysregulation represents one of the major driving forces in aging. Although multiple genetic and pharmacological manipulations are known to extend longevity in model organisms, aging is a complex trait, and targeting one's own genes may be insufficient to prevent age-dependent deterioration. An alternative strategy could be to use enzymes from other species to reverse age-associated metabolic changes. In this review, we discuss a set of enzymes from lower organisms that have been shown to affect various metabolic parameters linked to age-related processes. These enzymes include modulators of steady-state levels of amino acids (METase, ASNase, and ADI), NADPH/NADP+ and/or reduced form of coenzyme Q (CoQH2)/CoQ redox potentials (NDI1, AOX, LbNOX, TPNOX, EcSTH, RquA, LOXCAT, Grubraw, and ScURA), GSH (StGshF), mitochondrial membrane potential (mtON and mito-dR), or reactive oxygen species (DAAO and KillerRed-SOD1). We propose that leveraging non-mammalian enzymes represents an untapped resource that can be used to delay aging and age-related diseases.

Aspartate Metabolism-Driven Gut Microbiota Dynamics and RIP-Dependent Mitochondrial Function Counteract Oxidative Stress

Aspartate (Asp) metabolism-mediated antioxidant functions have important implications for neonatal growth and intestinal health; however, the antioxidant mechanisms through which Asp regulates the gut microbiota and influences RIP activation remain elusive. This study reports that chronic oxidative stress disrupts gut microbiota and metabolite balance and that such imbalance is intricately tied to the perturbation of Asp metabolism. Under normal conditions, in vivo and in vitro studies reveal that exogenous Asp improves intestinal health by regulating epithelial cell proliferation, nutrient uptake, and apoptosis. During oxidative stress, Asp reduces Megasphaera abundance while increasing Ruminococcaceae. This reversal effect depends on the enhanced production of the antioxidant eicosapentaenoic acid mediated through Asp metabolism and microbiota. Mechanistically, the application of exogenous Asp orchestrates the antioxidant responses in enterocytes via the modulation of the RIP3-MLKL and RIP1-Nrf2-NF-κB pathways to eliminate excessive reactive oxygen species and maintain mitochondrial functionality and cellular survival. These results demonstrate that Asp signaling alleviates oxidative stress by dynamically modulating the gut microbiota and RIP-dependent mitochondrial function, providing a potential therapeutic strategy for oxidative stress disease treatment.

Cancer ATF4-mediated CD58 endocytosis impairs anti-tumor immunity and immunotherapy

Co-stimulatory molecules are imperative for CD8+ T cells to eliminate target cell and maintain sustained cytotoxicity. Despite an advanced understanding of the co-stimulatory molecules deficiency that results in tumor escape, the tumor cell-intrinsic mechanisms that regulate co-stimulatory molecules remain enigmatic, and an in-depth dissection could facilitate the improvement of treatment options. To this end, in this study, we report that the deficiency of the critical costimulatory molecule CD58, mediated by the expression of ATF4 in tumor cells, impairs the formation of immunological synapses (IS) and leads to the deterioration of antitumor immune function of CD8+ T cells. Mechanistically, ATF4 transcriptionally upregulated dynamin 1 (DNM1) expression leading to DNM1-dependent endocytosis (DDE)-mediated degradation of CD58. Furthermore, administration of DDE inhibitor prochlorperazine or ATF4 knockdown effectively restored CD58 expression, boosting CD8+ T cell cytotoxicity and immunotherapy efficiency. Thus, our study reveals that ATF4 in tumor cells weakens CD58 expression to interfere with complete IS formation, and indicates potential approaches to improve the cytolytic function of CD8+ T cell in tumor immunotherapy.

Metabolomics' Change Under β-Cypermethrin Stress and Detoxification Role of CYP5011A1 in Tetrahymena thermophila

BACKGROUND

β-cypermethrin (β-CYP) exhibits high toxicity to aquatic organisms and poses significant risks to aquatic ecosystems. Tetrahymena thermophila, a protozoa widely distributed in aquatic environments, can tolerate high concentrations of β-cypermethrin. However, the comprehensive detoxification mechanisms remain poorly understood in Tetrahymena.

METHODS

Untargeted metabolomics was used to explore the detoxification mechanisms of T. thermophila under β-CYP stress.

RESULTS

Trehalose, maltose, glycerol, and D-myo-inositol were upregulated under β-CYP exposure in Tetrahymena. Furthermore, the expression level of CYP5011A1 was upregulated under β-CYP treatment. CYP5011A1 knockout mutants resulted in a decreasing proliferation rate of T. thermophila under β-CYP stress. The valine-leucine and isoleucine biosynthesis and glycine-serine and threonine metabolism were significantly affected, with significantly changed amino acids including serine, isoleucine, and valine.

CONCLUSIONS

These findings confirmed that T. thermophila develops β-CYP tolerance by carbohydrate metabolism reprogramming and Cyp5011A1 improves cellular adaptations by influencing amino acid metabolisms. Understanding these mechanisms can inform practices aimed at reducing the adverse effects of agricultural chemicals on microbial and environmental health.

Succinate Dehydrogenase loss causes cascading metabolic effects that impair pyrimidine biosynthesis

Impaired availability of the amino acid aspartate can be a metabolic constraint of cell proliferation in diverse biological contexts. However, the kinetics of aspartate depletion, and its ramifications on downstream metabolism and cell proliferation, remain poorly understood. Here, we deploy the aspartate biosensor jAspSnFR3 with live cell imaging to resolve temporal relationships between aspartate and cell proliferation from genetic, pharmacological, and nutritional manipulations. In cells with impaired aspartate acquisition from mitochondrial complex I inhibition or constrained uptake in aspartate auxotrophs, we find that the proliferation defects lag changes in aspartate levels and only manifest once aspartate levels fall below a critical threshold, supporting the functional link between aspartate levels and cell proliferation in these contexts. In another context of aspartate synthesis inhibition, impairing succinate dehydrogenase (SDH), we find a more complex metabolic interaction, with initial aspartate depletion followed by a rebound of aspartate levels over time. We find that this aspartate rebound effect results from SDH inhibition disproportionately impairing pyrimidine synthesis by inhibiting aspartate transcarbamoylase (ATCase) through the dual effect of diminishing aspartate substrate availability while accumulating succinate, which functions as a competitive inhibitor of aspartate utilization. Finally, we uncover that the nucleotide imbalance from SDH inhibition causes replication stress and introduces a vulnerability to ATR kinase inhibition. Altogether, these findings identify a mechanistic role for succinate in modulating nucleotide synthesis and demonstrate how cascading metabolic interactions can unfold to impact cell function.

Nanoscale octopus guiding telomere entanglement: An innovative strategy for inducing apoptosis in cancer cells

Telomere length plays a crucial role in cellular aging and the risk of diseases. Unlike normal cells, cancer cells can extend their own survival by maintaining telomere stability through telomere maintenance mechanism. Therefore, regulating the lengths of telomeres have emerged as a promising approach for anti-cancer treatment. In this study, we introduce a nanoscale octopus-like structure designed to induce physical entangling of telomere, thereby efficiently triggering telomere dysfunction. The nanoscale octopus, composed of eight-armed PEG (8-arm-PEG), are functionalized with cell penetrating peptide (TAT) to facilitate nuclear entry and are covalently bound to N-Methyl Mesoporphyrin IX (NMM) to target G-quadruplexes (G4s) present in telomeres. The multi-armed configuration of the nanoscale octopus enables targeted binding to multiple G4s, physically disrupting and entangling numerous telomeres, thereby triggering telomere dysfunction. Both in vitro and in vivo experiments indicate that the nanoscale octopus significantly inhibits cancer cell proliferation, induces apoptosis through telomere entanglement, and ultimately suppresses tumor growth. This research offers a novel perspective for the development of innovative anti-cancer interventions and provides potential therapeutic options for targeting telomeres.

Dietary fiber content in clinical ketogenic diets modifies the gut microbiome and seizure resistance in mice

The gut microbiome modulates the anti-seizure effects of the ketogenic diet, but how specific dietary formulations differentially modify the gut microbiome in ways that impact seizure outcome is poorly understood. We find that medical ketogenic infant formulas vary in macronutrient ratio, fat source, and fiber content and differentially promote resistance to 6-Hz seizures in mice. Dietary fiber, rather than fat ratio or source, drives substantial metagenomic shifts in a model human infant microbial community. Addition of fiber to a fiber-deficient ketogenic formula restores seizure resistance, and supplementing protective formulas with excess fiber potentiates seizure resistance. By screening 13 fiber sources and types, we identify metagenomic responses in the model community that correspond with increased seizure resistance. Supplementing with seizure-protective fibers enriches microbial genes related to queuosine biosynthesis and preQ0 biosynthesis and decreases genes related to sucrose degradation and TCA cycle, which are also seen in seizure-protected mice that are fed fiber-containing ketogenic formulas. This study reveals that different formulations of ketogenic diets, and dietary fiber content in particular, differentially impact seizure outcome in mice, likely by modifying the gut microbiome. Understanding interactions between diet, microbiome, and host susceptibility to seizures could inform novel microbiome-guided approaches to treat refractory epilepsy.

An Overview of Research Advances in Oncology Regarding the Transcription Factor ATF4

This review provides a comprehensive overview of the recent advancements in research on ATF4 (Activating Transcription Factor 4) within the field of oncology. As a crucial transcription factor, ATF4 has garnered increasing attention for its role in cancer research. The review begins with an exploration of the regulatory mechanisms of ATF4, including its transcriptional control, post-translational modifications, and interactions with other transcription factors. It then highlights key research findings on ATF4's involvement in various aspects of tumor biology, such as cell proliferation, differentiation, apoptosis and survival, invasion and metastasis, and the tumor microenvironment. Furthermore, the review discusses the potential of targeting ATF4 as a novel therapeutic strategy for cancer treatment. It also explores how ATF4's interactions with existing anticancer drugs could inform the development of more effective therapeutic agents. By elucidating the role of ATF4 in tumor biology and its potential clinical applications, this review aims to provide new insights and strategies for cancer treatment.

Serum targeted metabolomics uncovering specific amino acid signature for diagnosis of intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) is a hepatobiliary malignancy which accounts for approximately 5-10 % of primary liver cancers and has a high mortality rate. The diagnosis of iCCA remains significant challenges owing to the lack of specific and sensitive diagnostic tests available. Hence, improved methods are needed to detect iCCA with high accuracy. In this study, we evaluated the efficacy of serum amino acid profiling combined with machine learning modeling for the diagnosis of iCCA. A comprehensive analysis of 28 circulating amino acids was conducted in a total of 140 blood samples from patients with iCCA and normal individuals. We screened out 6 differentially expressed amino acids with the criteria of |Log2(Fold Change, FC)| > 0.585, P-value < 0.05, variable importance in projection (VIP) > 1.0 and area under the curve (AUC) > 0.8, in which amino acids L-Asparagine and Kynurenine showed an increasing tendency as the disease progressed. Five frequently used machine learning algorithms (Logistic Regression, Random Forest, Supporting Vector Machine, Neural Network and Naïve Bayes) for diagnosis of iCCA based on the 6 circulating amino acids were established and validated with high sensitivity and good overall accuracy. The resulting models were further improved by introducing a clinical indicator, gamma-glutamyl transferase (GGT). This study introduces a new approach for identifying potential serum biomarkers for the diagnosis of iCCA with high accuracy.

Transmembrane Amino Acid Transporters in Shaping the Metabolic Profile of Breast Cancer Cell Lines: The Focus on Molecular Biological Subtype

Amino acid metabolism in breast cancer cells is unique for each molecular biological subtype of breast cancer. In this review, the features of breast cancer cell metabolism are considered in terms of changes in the amino acid composition due to the activity of transmembrane amino acid transporters. In addition to the main signaling pathway PI3K/Akt/mTOR, the activity of the oncogene c-Myc, HIF, p53, GATA2, NF-kB and MAT2A have a direct effect on the amino acid metabolism of cancer cells, their growth and proliferation, as well as the maintenance of homeostatic equilibrium. A distinctive feature of luminal subtypes of breast cancer from TNBC is the ability to perform gluconeogenesis. Breast cancers with a positive expression of the HER2 receptor, in contrast to TNBC and luminal A subtype, have a distinctive active synthesis and consumption of fatty acids. It is interesting to note that amino acid transporters exhibit their activity depending on the pH level inside the cell. In the most aggressive forms of breast cancer or with the gradual progression of the disease, pH will also change, which will directly affect the metabolism of amino acids. Using the cell lines presented in this review, we can trace the characteristic features inherent in each of the molecular biological subtypes of breast cancer and develop the most optimal therapeutic targets.

Metformin targets mitochondrial complex I to lower blood glucose levels

Metformin is among the most prescribed antidiabetic drugs, but the primary molecular mechanism by which metformin lowers blood glucose levels is unknown. Previous studies have proposed numerous mechanisms by which acute metformin lowers blood glucose, including the inhibition of mitochondrial complex I of the electron transport chain (ETC). Here, we used transgenic mice that globally express the Saccharomyces cerevisiae internal alternative NADH dehydrogenase (NDI1) protein to determine whether the glucose-lowering effect of acute oral administration of metformin requires inhibition of mitochondrial complex I of the ETC in vivo. NDI1 is a yeast NADH dehydrogenase enzyme that complements the loss of mammalian mitochondrial complex I electron transport function and is insensitive to pharmacologic mitochondrial complex I inhibitors including metformin. We demonstrate that NDI1 expression attenuates metformin's ability to lower blood glucose levels under standard chow and high-fat diet conditions. Our results indicate that acute oral administration of metformin targets mitochondrial complex I to lower blood glucose.

Environmental sex reversal in parrotfish does not cause differences in the structure of their gut microbial communities

Parrotfish are a common fish in coral reef areas, but little is known about their gut microbial communities. In addition, parrotfish are capable of sex reversal, usually some males are sexually reversed from females, and it is still not known whether this sex reversal leads to significant changes in gut microbial communities. In this study, we investigated the gut microbial communities of three species of parrotfish including Scarus forsteni (4 females and 4 sex-reversed males), Scarus ghobban (5 females and 5 sex-reversed males), and Hipposcarus longiceps (5 females and 5 sex-reversed males) by using high-throughput sequencing technology. The gut microbial communities of these three species were mainly composed of Pseudomonadota (class Gammaproteobacteria) and Bacillota, while at the family level, they mainly included Vibrionaceae, Burkholderiaceae, Enterobacteriaceae, Streptococcacea, and Erwiniaceae. Although at the genus level, there were a large number of unclassified lineages, the remaining gut microorganisms were mainly composed of Vibrio, Photobacterium, Enterococcus and Lactococcus. Furthermore, we did not find significant differences in gut microbial community structure between the female parrotfish and corresponding female reversed males within each species, even in terms of the structure of gut microbial functional information obtained from 16 S rRNA gene sequence predictions. However, the gut microbial communities of these three species of parrotfish differed significantly not only in their community structure but also in their microbial functional information structure, mainly in terms of aspartate and asparagine biosynthesis, histidine degradation, inositol degradation, heptose biosynthesis, chitin derivatives degradation, enterobactin biosynthesis, and thiazole biosynthesis. Our study provides essential gut microbial community data for understanding the physiology and sex reversal phenomenon in parrotfish.

Targeting pivotal amino acids metabolism for treatment of leukemia

Metabolic reprogramming is a crucial characteristic of cancer, allowing cancer cells to acquire metabolic properties that support their survival, immune evasion, and uncontrolled proliferation. Consequently, targeting cancer metabolism has become an essential therapeutic strategy. Abnormal amino acid metabolism is not only a key aspect of metabolic reprogramming but also plays a significant role in chemotherapy resistance and immune evasion, particularly in leukemia. Changes in amino acid metabolism in tumor cells are typically driven by a combination of signaling pathways and transcription factors. Current approaches to targeting amino acid metabolism in leukemia include inhibiting amino acid transporters, blocking amino acid biosynthesis, and depleting specific amino acids to induce apoptosis in leukemic cells. Different types of leukemic cells rely on the exogenous supply of specific amino acids, such as asparagine, glutamine, arginine, and tryptophan. Therefore, disrupting the supply of these amino acids may represent a vulnerability in leukemia. This review focuses on the pivotal role of amino acids in leukemia metabolism, their impact on leukemic stem cells, and their therapeutic potential.

Asparagine availability controls germinal center B cell homeostasis

The rapid proliferation of germinal center (GC) B cells requires metabolic reprogramming to meet energy demands, yet these metabolic processes are poorly understood. By integrating metabolomic and transcriptomic profiling of GC B cells, we identified that asparagine (Asn) metabolism was highly up-regulated and essential for B cell function. Asparagine synthetase (ASNS) was up-regulated after B cell activation through the integrated stress response sensor GCN2. Conditional deletion of Asns in B cells impaired survival and proliferation in low Asn conditions. Removal of environmental Asn by asparaginase or dietary restriction compromised the GC reaction, impairing affinity maturation and the humoral response to influenza infection. Furthermore, metabolic adaptation to the absence of Asn required ASNS, and oxidative phosphorylation, mitochondrial homeostasis, and synthesis of nucleotides were particularly sensitive to Asn deprivation. These findings demonstrate that Asn metabolism acts as a key regulator of B cell function and GC homeostasis.

Dual inhibition of oxidative phosphorylation and glycolysis exerts a synergistic antitumor effect on colorectal and gastric cancer by creating energy depletion and preventing metabolic switch

Pyruvate is situated at the intersection of oxidative phosphorylation (OXPHOS) and glycolysis, which are the primary energy-producing pathways in cells. Cancer therapies targeting these pathways have been previously documented, indicating that inhibiting one pathway may lead to functional compensation by the other, resulting in an insufficient antitumor effect. Thus, effective cancer treatment necessitates concurrent and comprehensive suppression of both. However, whether a metabolic switch between the metabolic pathways occurs in colorectal and gastric cancer cells and whether blocking it by inhibiting both pathways has an antitumor effect remain to be determined. In the present study, we used two small molecules, namely OXPHOS and glycolysis inhibitors, to target pyruvate metabolic pathways as a cancer treatment in these cancer cells. OXPHOS and glycolysis inhibition each augmented the other metabolic pathway in vitro and in vivo. OXPHOS inhibition alone enhanced glycolysis and showed antitumor effects on colorectal and gastric cancer cells in vitro and in vivo. Moreover, glycolysis inhibition in addition to OXPHOS inhibition blocked the metabolic switch from OXPHOS to glycolysis, causing an energy depletion and deterioration of the tumor microenvironment that synergistically enhanced the antitumor effect of OXPHOS inhibitors. In addition, using hyperpolarized 13C-magnetic resonance spectroscopic imaging (HP-MRSI), which enables real-time and in vivo monitoring of molecules containing 13C, we visualized how the inhibitors shifted the flux of pyruvate and how this dual inhibition in colorectal and gastric cancer mouse models altered the two pathways. Integrating dual inhibition of OXPHOS and glycolysis with HP-MRSI, this therapeutic model shows promise as a future "cancer theranostics" treatment option.

Diet and Cancer Metabolism

Diet and exercise are modifiable lifestyle factors known to have a major influence on metabolism. Clinical practice addresses diseases of altered metabolism such as diabetes or hypertension by altering these factors. Despite enormous public interest, there are limited defined diet and exercise regimens for cancer patients. Nevertheless, the molecular basis of cancer has converged over the past 15 years on an essential role for altered metabolism in cancer. However, our understanding of the molecular mechanisms that underlie the impact of diet and exercise on cancer metabolism is in its very early stages. In this work, we propose conceptual frameworks for understanding the consequences of diet and exercise on cancer cell metabolism and tumor biology and also highlight recent developments. By advancing our mechanistic understanding, we also discuss actionable ways that such interventions could eventually reach the mainstay of both medical oncology and cancer control and prevention.

Mitochondria and Cancer

Mitochondria are semiautonomous organelles with diverse metabolic and cellular functions including anabolism and energy production through oxidative phosphorylation. Following the pioneering observations of Otto Warburg nearly a century ago, an immense body of work has examined the role of mitochondria in cancer pathogenesis and progression. Here, we summarize the current state of the field, which has coalesced around the position that functional mitochondria are required for cancer cell proliferation. In this review, we discuss how mitochondria influence tumorigenesis by impacting anabolism, intracellular signaling, and the tumor microenvironment. Consistent with their critical functions in tumor formation, mitochondria have become an attractive target for cancer therapy. We provide a comprehensive update on the numerous therapeutic modalities targeting the mitochondria of cancer cells making their way through clinical trials.

Targeting purine metabolism-related enzymes for therapeutic intervention: A review from molecular mechanism to therapeutic breakthrough

Purines are ancient metabolites with established and emerging metabolic and non-metabolic signaling attributes. The expression of purine metabolism-related genes is frequently activated in human malignancies, correlating with increased cancer aggressiveness and chemoresistance. Importantly, under certain stimulating conditions, the purine biosynthetic enzymes can assemble into a metabolon called "purinosomes" to enhance purine flux. Current evidence suggests that purine flux is regulated by a complex circuit that encompasses transcriptional, post-translational, metabolic, and association-dependent regulatory mechanisms. Furthermore, purines within the tumor microenvironment modulate cancer immunity through signaling mediated by purinergic receptors. The deregulation of purine metabolism has significant metabolic consequences, particularly hyperuricemia. Herbal-based therapeutics have emerged as valuable pharmacological interventions for the treatment of hyperuricemia by inhibiting the activity of hepatic XOD, modulating the expression of renal urate transporters, and suppressing inflammatory responses. This review summarizes recent advancements in the understanding of purine metabolism in clinically relevant malignancies and metabolic disorders. Additionally, we discuss the role of herbal interventions and the interaction between the host and gut microbiota in the regulation of purine homeostasis. This information will fuel the innovation of therapeutic strategies that target the disease-associated rewiring of purine metabolism for therapeutic applications.

Aspartate in tumor microenvironment and beyond: Metabolic interactions and therapeutic perspectives

Aspartate is a proteinogenic non-essential amino acid with several essential functions in proliferating cells. It is mostly produced in a cell autonomous manner from oxalacetate via glutamate oxalacetate transaminases 1 or 2 (GOT1 or GOT2), but in some cases it can also be salvaged from the microenvironment via transporters such as SLC1A3 or by macropinocytosis. In this review we provide an overview of biosynthetic pathways that produce aspartate endogenously during proliferation. We discuss conditions that favor aspartate uptake as well as possible sources of exogenous aspartate in the microenvironment of tumors and bone marrow, where most available data have been generated. We highlight metabolic fates of aspartate, its various functions, and possible approaches to target aspartate metabolism for cancer therapy.

Loss of USP10 promotes hepatocellular carcinoma proliferation by regulating the serine synthesis pathway through inhibition of LKB1 activity

Metabolic dysregulation is emerging as a critical factor in tumorigenesis, and reprogramming of serine metabolism has been identified as an essential factor in the progression of hepatocellular carcinoma (HCC). Studies have shown that LKB1 deficiency can activate mTOR to upregulate the serine synthesis pathway (SSP) and promote tumor progression. Our team discovered that ubiquitin-specific protease 10 (USP10) can inhibit HCC proliferation through mTOR, but its relationship with SSP needs further investigation. The metabolite assays revealed a significant increase in serine content in HCC tissues. Through the LKB1/mTOR/activating transcription factor 4 (ATF4) axis, loss of USP10 may increase serine biosynthesis and promote the proliferation of HCC in vitro and in vivo. Furthermore, it was found that USP10 could activate LKB1 through deubiquitination. Analyzing clinical HCC tissues revealed a positive correlation between USP10 and LKB1. Additionally, those with high expression of USP10 in HCC tissues showed a better degree of tumor differentiation and longer overall survival time. Moreover, we found increased expression of both serine and its synthase in liver tumor tissues of USP10 liver-specific KO mice. Loss of USP10 inhibits the activity of LKB1, contributing to the stimulation of the mTOR/ATF4 axis and SSP and then promoting the proliferation of HCC. This work presents a novel approach for serine-targeted treatment in HCC.

Identifying targetable metabolic dependencies across colorectal cancer progression

Colorectal cancer (CRC) is a multi-stage process initiated through the formation of a benign adenoma, progressing to an invasive carcinoma and finally metastatic spread. Tumour cells must adapt their metabolism to support the energetic and biosynthetic demands associated with disease progression. As such, targeting cancer cell metabolism is a promising therapeutic avenue in CRC. However, to identify tractable nodes of metabolic vulnerability specific to CRC stage, we must understand how metabolism changes during CRC development. Here, we use a unique model system - comprising human early adenoma to late adenocarcinoma. We show that adenoma cells transition to elevated glycolysis at the early stages of tumour progression but maintain oxidative metabolism. Progressed adenocarcinoma cells rely more on glutamine-derived carbon to fuel the TCA cycle, whereas glycolysis and TCA cycle activity remain tightly coupled in early adenoma cells. Adenocarcinoma cells are more flexible with respect to fuel source, enabling them to proliferate in nutrient-poor environments. Despite this plasticity, we identify asparagine (ASN) synthesis as a node of metabolic vulnerability in late-stage adenocarcinoma cells. We show that loss of asparagine synthetase (ASNS) blocks their proliferation, whereas early adenoma cells are largely resistant to ASN deprivation. Mechanistically, we show that late-stage adenocarcinoma cells are dependent on ASNS to support mTORC1 signalling and maximal glycolytic and oxidative capacity. Resistance to ASNS loss in early adenoma cells is likely due to a feedback loop, absent in late-stage cells, allowing them to sense and regulate ASN levels and supplement ASN by autophagy. Together, our study defines metabolic changes during CRC development and highlights ASN synthesis as a targetable metabolic vulnerability in later stage disease.

The Integrated Stress Response in Pancreatic Development, Tissue Homeostasis, and Cancer

Present in all eukaryotic cells, the integrated stress response (ISR) is a highly coordinated signaling network that controls cellular behavior, metabolism, and survival in response to diverse stresses. The ISR is initiated when any 1 of 4 stress-sensing kinases (protein kinase R-like endoplasmic reticulum kinase [PERK], general control non-derepressible 2 [GCN2], double-stranded RNA-dependent protein kinase [PKR], heme-regulated eukaryotic translation initiation factor 2α kinase [HRI]) becomes activated to phosphorylate the protein translation initiation factor eukaryotic translation initiation factor 2α (eIF2α), shifting gene expression toward a comprehensive rewiring of cellular machinery to promote adaptation. Although the ISR has been shown to play an important role in the homeostasis of multiple tissues, evidence suggests that it is particularly crucial for the development and ongoing health of the pancreas. Among the most synthetically dynamic tissues in the body, the exocrine and endocrine pancreas relies heavily on the ISR to rapidly adjust cell function to meet the metabolic demands of the organism. The hardwiring of the ISR into normal pancreatic functions and adaptation to stress may explain why it is a commonly used pro-oncogenic and therapy-resistance mechanism in pancreatic ductal adenocarcinoma and pancreatic neuroendocrine tumors. Here, we review what is known about the key roles that the ISR plays in the development, homeostasis, and neoplasia of the pancreas.

Salmonella cancer therapy metabolically disrupts tumours at the collateral cost of T cell immunity

Bacterial cancer therapy (BCT) is a promising therapeutic for solid tumours. Salmonella enterica Typhimurium (STm) is well-studied amongst bacterial vectors due to advantages in genetic modification and metabolic adaptation. A longstanding paradox is the redundancy of T cells for treatment efficacy; instead, STm BCT depends on innate phagocytes for tumour control. Here, we used distal T cell receptor (TCR) and IFNγ reporter mice (Nr4a3-Tocky-Ifnγ-YFP) and a colorectal cancer (CRC) model to interrogate T cell activity during BCT with attenuated STm. We found that colonic tumour infiltrating lymphocytes (TILs) exhibited a variety of activation defects, including IFN-γ production decoupled from TCR signalling, decreased polyfunctionality and reduced central memory (TCM) formation. Modelling of T-cell-tumour interactions with a tumour organoid platform revealed an intact TCR signalosome, but paralysed metabolic reprogramming due to inhibition of the master metabolic controller, c-Myc. Restoration of c-Myc by deletion of the bacterial asparaginase ansB reinvigorated T cell activation, but at the cost of decreased metabolic control of the tumour by STm. This work shows for the first time that T cells are metabolically defective during BCT, but also that this same phenomenon is inexorably tied to intrinsic tumour suppression by the bacterial vector.

Genetically encoded fluorescent reporter for polyamines

Polyamines are abundant and evolutionarily conserved metabolites that are essential for life. Dietary polyamine supplementation extends life-span and health-span. Dysregulation of polyamine homeostasis is linked to Parkinson's disease and cancer, driving interest in therapeutically targeting this pathway. However, measuring cellular polyamine levels, which vary across cell types and states, remains challenging. We introduce a first-in-class genetically encoded polyamine reporter for real-time measurement of polyamine concentrations in single living cells. This reporter utilizes the polyamine-responsive ribosomal frameshift motif from the OAZ1 gene. We demonstrate broad applicability of this approach and reveal dynamic changes in polyamine levels in response to genetic and pharmacological perturbations. Using this reporter, we conducted a genome-wide CRISPR screen and uncovered an unexpected link between mitochondrial respiration and polyamine import, which are both risk factors for Parkinson's disease. By offering a new lens to examine polyamine biology, this reporter may advance our understanding of these ubiquitous metabolites and accelerate therapy development.

Asparagine as a signal for glutamine sufficiency via asparagine synthetase: a fresh evidence-based framework in physiology and oncology

Among the 20 proteinogenic amino acids, glutamine (GLN) and asparagine (ASN) represent a unique cohort in containing a terminal amide in their side chain, and share a direct metabolic relationship, with glutamine generating asparagine through the ATP-dependent asparagine synthetase (ASNS) reaction. Circulating glutamine levels and metabolic flux through cells and tissues greatly exceed those for asparagine, and "glutamine addiction" in cancer has likewise received considerable attention. However, historic and recent evidence collectively suggest that in spite of its modest presence, asparagine plays an outsized regulatory role in cellular function. Here, we present a unifying evidence-based hypothesis that the amides constitute a regulatory signaling circuit, with glutamine as a driver and asparagine as a second messenger that allosterically regulates key biochemical and physiological functions, particularly cell growth and survival. Specifically, it is proposed that ASNS serves as a sensor of substrate sufficiency for S-phase entry and progression in proliferating cells. ASNS-generated asparagine serves as a subsequent second messenger that modulates the activity of key regulatory proteins and promotes survival in the face of cellular stress, and serves as a feed-forward driver of S-phase progression in cell growth. We propose that this signaling pathway be termed the amide signaling circuit (ASC) in homage to the SLC1A5-encoded ASCT2 that transports both glutamine and asparagine in a bidirectional manner, and has been implicated in the pathogenesis of a broad spectrum of human cancers. Support for the ASC model is provided by the recent discovery that glutamine is sensed in primary cilia via ASNS during metabolic stress.

HSP60 chaperone deficiency disrupts the mitochondrial matrix proteome and dysregulates cholesterol synthesis

OBJECTIVE

Mitochondrial proteostasis is critical for cellular function. The molecular chaperone HSP60 is essential for cell function and dysregulation of HSP60 expression has been implicated in cancer and diabetes. The few reported patients carrying HSP60 gene variants show neurodevelopmental delay and brain hypomyelination. Hsp60 interacts with more than 260 mitochondrial proteins but the mitochondrial proteins and functions affected by HSP60 deficiency are poorly characterized.

METHODS

We studied two model systems for HSP60 deficiency: (1) engineered HEK cells carrying an inducible dominant negative HSP60 mutant protein, (2) zebrafish HSP60 knockout larvae. Both systems were analyzed by RNASeq, proteomics, and targeted metabolomics, and several functional assays relevant for the respective model. In addition, skin fibroblasts from patients with disease-associated HSP60 variants were analyzed by proteomics.

RESULTS

We show that HSP60 deficiency leads to a differentially downregulated mitochondrial matrix proteome, transcriptional activation of stress responses, and dysregulated cholesterol biosynthesis. This leads to lipid accumulation in zebrafish knockout larvae.

CONCLUSIONS

Our data provide a compendium of the effects of HSP60 deficiency on the mitochondrial matrix proteome. We show that HSP60 is a master regulator and modulator of mitochondrial functions and metabolic pathways. HSP60 dysfunction also affects cellular metabolism and disrupts the integrated stress response. The effect on cholesterol synthesis explains the effect of HSP60 dysfunction on myelination observed in patients carrying genetic variants of HSP60.

Targeting NAT10 inhibits osteosarcoma progression via ATF4/ASNS-mediated asparagine biosynthesis

Despite advances in treatment, the prognosis of patients with osteosarcoma remains unsatisfactory, and searching for potential targets is imperative. Here, we identify N4-acetylcytidine (ac4C) acetyltransferase 10 (NAT10) as a candidate therapeutic target in osteosarcoma through functional screening. NAT10 overexpression is correlated with a poor prognosis, and NAT10 knockout inhibits osteosarcoma progression. Mechanistically, NAT10 enhances mRNA stability of activating transcription factor 4 (ATF4) through ac4C modification. ATF4 induces the transcription of asparagine synthetase (ASNS), which catalyzes asparagine (Asn) biosynthesis, facilitating osteosarcoma progression. Utilizing virtual screening, we identify paliperidone and AG-401 as potential NAT10 inhibitors, and both inhibitors are found to bind to NAT10 proteins. Inhibiting NAT10 suppresses osteosarcoma progression in vivo. Combined treatment using paliperidone and AG-401 produces synergistic inhibition for osteosarcoma in patient-derived xenograft (PDX) models. Our findings demonstrate that NAT10 facilitates osteosarcoma progression through the ATF4/ASNS/Asn axis, and pharmacological inhibition of NAT10 may be a feasible therapeutic approach for osteosarcoma.

Lactic acid: The culprit behind the immunosuppressive microenvironment in hepatocellular carcinoma

As a solid tumor with high glycolytic activity, hepatocellular carcinoma (HCC) produces excess lactic acid and increases extracellular acidity, thus forming a unique immunosuppressive microenvironment. L-lactate dehydrogenase (LDH) and monocarboxylate transporters (MCTs) play a very important role in glycolysis. LDH is the key enzyme for lactic acid (LA) production, and MCT is responsible for the cellular import and export of LA. The synergistic effect of the two promotes the formation of an extracellular acidic microenvironment. In the acidic microenvironment of HCC, LA can not only promote the proliferation, survival, transport and angiogenesis of tumor cells but also have a strong impact on immune cells, ultimately leading to an inhibitory immune microenvironment. This article reviews the role of LA in HCC, especially its effect on immune cells, summarizes the progress of LDH and MCT-related drugs, and highlights the potential of immunotherapy targeting lactate combined with HCC.

Exploring the impact of flavin homeostasis on cancer cell metabolism

Flavins and their associated proteins have recently emerged as compelling players in the landscape of cancer biology. Flavins, encompassing flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), serve as coenzymes in a multitude of cellular processes, such as metabolism, apoptosis, and cell proliferation. Their involvement in oxidative phosphorylation, redox homeostasis, and enzymatic reactions has long been recognized. However, recent research has unveiled an extended role for flavins in the context of cancer. In parallel, riboflavin transporters (RFVTs), FAD synthase (FADS), and riboflavin kinase (RFK) have gained prominence in cancer research. These proteins, responsible for riboflavin uptake, FAD biosynthesis, and FMN generation, are integral components of the cellular machinery that governs flavin homeostasis. Dysregulation in the expression/function of these proteins has been associated with various cancers, underscoring their potential as diagnostic markers, therapeutic targets, and key determinants of cancer cell behavior. This review embarks on a comprehensive exploration of the multifaceted role of flavins and of the flavoproteins involved in nucleus-mitochondria crosstalk in cancer. We journey through the influence of flavins on cancer cell energetics, the modulation of RFVTs in malignant transformation, the diagnostic and prognostic significance of FADS, and the implications of RFK in drug resistance and apoptosis. This review also underscores the potential of these molecules and processes as targets for novel diagnostic and therapeutic strategies, offering new avenues for the battle against this relentless disease.

SLC25A19 is required for NADH homeostasis and mitochondrial respiration

Mitochondrial transporters facilitate the translocation of metabolites between the cytoplasm and mitochondria and are critical for mitochondrial functional integrity. Although many mitochondrial transporters are associated with metabolic diseases, how they regulate mitochondrial function and their metabolic contributions at the cellular level are largely unknown. Here, we show that mitochondrial thiamine pyrophosphate (TPP) transporter SLC25A19 is required for mitochondrial respiration. SLC25A19 deficiency leads to reduced cell viability, increased integrated stress response (ISR), enhanced glycolysis and elevated cell sensitivity to 2-deoxyglucose (2-DG) treatment. Through a series of biochemical assays, we found that the depletion of mitochondrial NADH is the primary cause of the impaired mitochondrial respiration in SLC25A19 deficient cells. We also showed involvement of SLC25A19 in regulating the enzymatic activities of complexes I and III, the tricarboxylic acid (TCA) cycle, malate-aspartate shuttle and amino acid metabolism. Consistently, addition of idebenone, an analog of coenzyme Q10, restores mitochondrial respiration and cell viability in SLC25A19 deficient cells. Together, our findings provide new insight into the functions of SLC25A19 in mitochondrial and cellular physiology, and suggest that restoring mitochondrial respiration could be a novel strategy for treating SLC25A19-associated disorders.

Characterization and validation of a prognostic model for the N6-methyladenosine-associated ferroptosis gene in colon adenocarcinoma

Background

According to statistics, colon adenocarcinoma (COAD) ranks third in global incidence and second in mortality. The role of N6-methyladenosine (m6A) modification-dependent ferroptosis in tumor development and progression is gaining attention. Therefore, it is meaningful to explore the biological functions mediated by m6A ferroptosis related genes (m6A-Ferr-RGs) in the prognosis and treatment of COAD. This study aimed to explore the regulatory mechanisms and prognostic features of m6A-Ferr-RGs in COAD based on the COAD transcriptome dataset.

Methods

The expression data of Ferr-RGs and the correlated analysis with prognosis related m6A regulators were conducted to obtain candidate m6A-Ferr-RGs. Then, the differentially expressed genes (DEGs) between COAD and normal samples were intersected with candidate m6A-Ferr-RGs to obtain differentially expressed m6A Ferr-RGs (DE-m6A-Ferr-RGs) in COAD. Cox regression analyses were performed to establish risk model and validated in the GSE17538 and GSE41258 datasets. The nomogram was constructed and verified by calibration curves. Moreover, tumor immune dysfunction and exclusion (TIDE) was used to assess immunotherapy response in two risk groups. Finally, the expression of m6A-Ferr-related prognostic genes was validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR).

Results

In total, 6 model genes (HSD17B11, VEGFA, CXCL2, ASNS, FABP4, and GPX2) were obtained to construct the risk model. The nomogram was established based on the independent prognostic factors for predicting survival of COAD. TIDE assessed that the high-risk group suffered from greater immune resistance. Ultimately, the experimental results confirmed that the expression trends of all model genes were consistent among data from public database.

Conclusions

In this study, m6A-Ferr-related prognostic model for COAD was constructed using transcriptome data and clinical data of COAD in public database, which may have potential immunotherapy and chemotherapy guidance implications.

Targeting Asparagine Metabolism in Well-Differentiated/Dedifferentiated Liposarcoma

BACKGROUND

mTORC1 activity is dependent on the presence of micronutrients, including Asparagine (Asn), to promote anabolic cell signaling in many cancers. We hypothesized that targeting Asn metabolism would inhibit tumor growth by reducing mTORC1 activity in well-differentiated (WD)/dedifferentiated (DD) liposarcoma (LPS).

METHODS

Human tumor metabolomic analysis was utilized to compare abundance of Asn in WD vs. DD LPS. Gene set enrichment analysis (GSEA) compared relative expression among metabolic pathways upregulated in DD vs. WD LPS. Proliferation assays were performed for LPS cell lines and organoid models by using the combination treatment of electron transport chain (ETC) inhibitors with Asn-free media. 13C-Glucose-labeling metabolomics evaluated the effects of combination treatment on nucleotide synthesis. Murine xenograft models were used to assess the effects of ETC inhibition combined with PEGylated L-Asparaginase (PEG-Asnase) on tumor growth and mTORC1 signaling.

RESULTS

Asn was enriched in DD LPS compared to WD LPS. GSEA indicated that mTORC1 signaling was upregulated in DD LPS. Within available LPS cell lines and organoid models, the combination of ETC inhibition with Asn-free media resulted in reduced cell proliferation. Combination treatment inhibited nucleotide synthesis and promoted cell cycle arrest. In vivo, the combination of ETC inhibition with PEG-Asnase restricted tumor growth.

CONCLUSIONS

Asn enrichment and mTORC1 upregulation are important factors contributing to WD/DD LPS tumor progression. Effective targeting strategies require limiting access to extracellular Asn and inhibition of de novo synthesis mechanisms. The combination of PEG-Asnase with ETC inhibition is an effective therapy to restrict tumor growth in WD/DD LPS.

Differential effect of asparagine and glutamine removal on three adenocarcinoma cell lines

Asparagine and glutamine depletion operated by the drug Asparaginase (ASNase) has revolutionized therapy in pediatric patients affected by Acute Lymphoblastic Leukemia (ALL), bringing remissions to a remarkable 90 % of cases. However, the knowledge of the proproliferative role of asparagine in adult and solid tumors is still limited. We have here analyzed the effect of ASNase on three adenocarcinoma cell lines (A549, lung adenocarcinoma, MCF-7, breast cancer, and 786-O, kidney cancer). In contrast to MCF-7 cells, 786-O and A549 cells proved to be a relevant target for cell cycle perturbation by asparagine and glutamine shortage. Indeed, when the cell-cycle was analyzed by flow cytometry, A549 showed a canonical response to asparaginase, 786-O cells, instead, showed a reduction of the percentage of cells in the G1 phase and an increase of those in the S-phase. Despite an increased number of PCNA and RPA70 positive nuclear foci, BrdU and EdU incorporation was absent or strongly delayed in treated 786-O cells, thus indicating a readiness of replication forks unmatched by DNA synthesis. In 786-O asparagine synthetase was reduced following treatment and glutamine synthetase was totally absent. Interestingly, DNA synthesis could be recovered by adding Gln to the medium. MCF-7 cells showed no significant changes in the cell cycle phases, in DNA-bound PCNA and in total PCNA, but a significant increase in ASNS and GS mRNA and protein expression. The collected data suggest that the effect observed on 786-O cells following ASNase treatment could rely on mechanisms which differ from those well-known and described for leukemic blasts, consisting of a complete block in the G1/S transition in proliferating cells and on an increase on non-proliferative (G0) blasts.

Fer governs mTORC1 regulating pathways and sustains viability of pancreatic ductal adenocarcinoma cells

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers with a high percentage of morbidity. The deciphering and identification of novel targets and tools for intervening with its adverse progression are therefore of immense importance. To address this goal we adopted a specific inhibitor of the intracellular tyrosine kinase Fer, whose expression level is upregulated in PDAC tumors, and is associated with poor prognosis of patients. Subjecting PDAC cells to the E260-Fer inhibitor, unraveled its simultaneous effects on the mitochondria, and on a non-mitochondrial ERK1/2 regulatory cascade. E260 caused severe mitochondrial deformation, resulting in cellular- aspartate and ATP depletion, and followed by the activation of the metabolic sensor AMPK. This led to the phosphorylation and deactivation of the bona fide AMPK substrate, RAPTOR, which serves as a positive regulator of the mTORC1 metabolic hub. Accordingly, this resulted in the inhibition of the mTORC1 activity. In parallel, E260 downregulated the activation state of the ERK1/2 kinases, and their ability to neutralize the mTORC1 suppressor TSC2, thereby accentuating the inhibition of mTORC1. Importantly, both activation of AMPK and downregulation of ERK1/2 and mTORC1 were also achieved upon the knockdown of Fer, corroborating the regulatory role of Fer in these processes. Concomitantly, in PDAC tumors and not in healthy pancreatic tissues, the expression levels of Fer demonstrate moderate but statistically significant positive correlation with the expression levels of mTOR and its downstream effector LARP1. Finally, targeting the Fer driven activation of mTORC1, culminated in necrotic death of the treated PDAC cells, envisaging a new intervention tool for the challenging PDAC disease.

Mitochondrial respiration in microglia is essential for response to demyelinating injury but not proliferation

Microglia are necessary for central nervous system (CNS) function during development and play roles in ageing, Alzheimer's disease and the response to demyelinating injury1-5. The mitochondrial respiratory chain (RC) is necessary for conventional T cell proliferation6 and macrophage-dependent immune responses7-10. However, whether mitochondrial RC is essential for microglia proliferation or function is not known. We conditionally deleted the mitochondrial complex III subunit Uqcrfs1 (Rieske iron-sulfur polypeptide 1) in the microglia of adult mice to assess the requirement of microglial RC for survival, proliferation and adult CNS function in vivo. Notably, mitochondrial RC function was not required for survival or proliferation of microglia in vivo. RNA sequencing analysis showed that loss of RC function in microglia caused changes in gene expression distinct from aged or disease-associated microglia. Microglia-specific loss of mitochondrial RC function is not sufficient to induce cognitive decline. Amyloid-β plaque coverage decreased and microglial interaction with amyloid-β plaques increased in the hippocampus of 5xFAD mice with mitochondrial RC-deficient microglia. Microglia-specific loss of mitochondrial RC function did impair remyelination following an acute, reversible demyelinating event. Thus, mitochondrial respiration in microglia is dispensable for proliferation but is essential to maintain a proper response to CNS demyelinating injury.

Asparagine: A key metabolic junction in targeted tumor therapy

Nutrient bioavailability in the tumor microenvironment plays a pivotal role in tumor proliferation and metastasis. Among these nutrients, glutamine is a key substance that promotes tumor growth and proliferation, and its downstream metabolite asparagine is also crucial in tumors. Studies have shown that when glutamine is exhausted, tumor cells can rely on asparagine to sustain their growth. Given the reliance of tumor cell proliferation on asparagine, restricting its bioavailability has emerged as promising strategy in cancer treatment. For instance, the use of asparaginase, an enzyme that depletes asparagine, has been one of the key chemotherapies for acute lymphoblastic leukemia (ALL). However, tumor cells can adapt to asparagine restriction, leading to reduced chemotherapy efficacy, and the mechanisms by which different genetically altered tumors are sensitized or adapted to asparagine restriction vary. We review the sources of asparagine and explore how limiting its bioavailability impacts the progression of specific genetically altered tumors. It is hoped that by targeting the signaling pathways involved in tumor adaptation to asparagine restriction and certain factors within these pathways, the issue of drug resistance can be addressed. Importantly, these strategies offer precise therapeutic approaches for genetically altered cancers.

The significant role of amino acid metabolic reprogramming in cancer

Amino acid metabolism plays a pivotal role in tumor microenvironment, influencing various aspects of cancer progression. The metabolic reprogramming of amino acids in tumor cells is intricately linked to protein synthesis, nucleotide synthesis, modulation of signaling pathways, regulation of tumor cell metabolism, maintenance of oxidative stress homeostasis, and epigenetic modifications. Furthermore, the dysregulation of amino acid metabolism also impacts tumor microenvironment and tumor immunity. Amino acids can act as signaling molecules that modulate immune cell function and immune tolerance within the tumor microenvironment, reshaping the anti-tumor immune response and promoting immune evasion by cancer cells. Moreover, amino acid metabolism can influence the behavior of stromal cells, such as cancer-associated fibroblasts, regulate ECM remodeling and promote angiogenesis, thereby facilitating tumor growth and metastasis. Understanding the intricate interplay between amino acid metabolism and the tumor microenvironment is of crucial significance. Expanding our knowledge of the multifaceted roles of amino acid metabolism in tumor microenvironment holds significant promise for the development of more effective cancer therapies aimed at disrupting the metabolic dependencies of cancer cells and modulating the tumor microenvironment to enhance anti-tumor immune responses and inhibit tumor progression.

Current advances in cancer energy metabolism under dietary restriction: a mini review

The manipulation of the energy or source of food for cancer cells has attracted significant attention in oncology research. Metabolic reprogramming of the immune system allows for a deeper understanding of cancer cell mechanisms, thereby impeding their progression. A more targeted approach is the restriction of cancer cells through dietary restriction (CR), which deprives cancer cells of the preferred energy sources within the tumor microenvironment, thereby enhancing immune cell efficacy. Although there is a plethora of CR strategies that can be employed to impede cancer progression, there is currently no comprehensive review that delineates the specific dietary restrictions that target the diverse metabolic pathways of cancer cells. This mini-review introduces amino acids as anti-cancer agents and discusses the role of dietary interventions in cancer prevention and treatment. It highlights the potential of a ketogenic diet as a therapeutic approach for cancer, elucidating its distinct mechanisms of action in tumor progression. Additionally, the potential of plant-based diets as anti-cancer agents and the role of polyphenols and vitamins in anti-cancer therapy were also discussed, along with some prospective interventions for CR as anti-tumor progression.

Construction of prognostic markers for pancreatic adenocarcinoma based on mitochondrial fusion-related genes

Early detection of pancreatic adenocarcinoma (PAAD) remains a pressing clinical problem. Information on the clinical prognostic value of mitochondrial fusion-related genes in PAAD remains limited. In this study, we investigated mitochondrial fusion-related genes of PAAD to establish an optimal signature plate for the early diagnosis and prognosis of PAAD. The cancer genome atlas database was used to integrate the Fragments Per Kilobase Million data and related clinical data for patients with PAAD. Least absolute shrinkage and selection operator regression, cox regression, operating characteristic curves, and cBioPortal database was used to evaluate model performance, assess the prognostic ability and sensitivity. The levels of immune infiltration were compared by CIBERSORT, QUANTISEQ, and EPIC. Chemotherapy sensitivity between the different risk groups was compared by the Genomics of Drug Sensitivity in Cancer database and the "pRRophetic" R package. At last, a total of 4 genes were enrolled in multivariate Cox regression analysis. The risk-predictive signature was constructed as: (0.5438 × BAK1) + (-1.0259 × MIGA2) + (1.1140 × PARL) + (-0.4300 × PLD6). The area under curve of these 4 genes was 0.89. Cox regression analyses indicates the signature was an independent prognostic indicator (P < .001, hazard ratio [HR] = 1.870, 95% CI = 1.568-2.232). Different levels of immune cell infiltration in the 2 risk groups were observed using the 3 algorithms, with tumor mutation load (P = .0063), tumor microenvironment score (P = .01), and Tumor Immune Dysfunction and Exclusion score (P = .0012). The chemotherapeutic sensitivity analysis also revealed that the half-maximal inhibitory concentration of 5-fluorouracil (P = .0127), cisplatin (P = .0099), docetaxel (P < .0001), gemcitabine (P = .0047), and pacilataxel (P < .0001) were lower in the high-risk groups, indicating that the high-risk group patients had a greater sensitivity to chemotherapy. In conclude, we established a gene signature plate comprised of 4 mitochondrial fusion related genes to facilitate early diagnosis and prognostic prediction of PAAD.

A diverse proteome is present and enzymatically active in metabolite extracts

Metabolite extraction is the critical first-step in metabolomics experiments, where it is generally regarded to inactivate and remove proteins. Here, arising from efforts to improve extraction conditions for polar metabolomics, we discover a proteomic landscape of over 1000 proteins within metabolite extracts. This is a ubiquitous feature across several common extraction and sample types. By combining post-resuspension stable isotope addition and enzyme inhibitors, we demonstrate in-extract metabolite interconversions due to residual transaminase activity. We extend these findings with untargeted metabolomics where we observe extensive protein-mediated metabolite changes, including in-extract formation of glutamate dipeptide and depletion of total glutathione. Finally, we present a simple extraction workflow that integrates 3 kDa filtration for protein removal as a superior method for polar metabolomics. In this work, we uncover a previously unrecognized, protein-mediated source of observer effects in metabolomics experiments with broad-reaching implications across all research fields using metabolomics and molecular metabolism.

Electron transport chain inhibition increases cellular dependence on purine transport and salvage

Mitochondria house many metabolic pathways required for homeostasis and growth. To explore how human cells respond to mitochondrial dysfunction, we performed metabolomics in fibroblasts from patients with various mitochondrial disorders and cancer cells with electron transport chain (ETC) blockade. These analyses revealed extensive perturbations in purine metabolism, and stable isotope tracing demonstrated that ETC defects suppress de novo purine synthesis while enhancing purine salvage. In human lung cancer, tumors with markers of low oxidative mitochondrial metabolism exhibit enhanced expression of the salvage enzyme hypoxanthine phosphoribosyl transferase 1 (HPRT1) and high levels of the HPRT1 product inosine monophosphate. Mechanistically, ETC blockade activates the pentose phosphate pathway, providing phosphoribosyl diphosphate to drive purine salvage supplied by uptake of extracellular bases. Blocking HPRT1 sensitizes cancer cells to ETC inhibition. These findings demonstrate how cells remodel purine metabolism upon ETC blockade and uncover a new metabolic vulnerability in tumors with low respiration.

Switch of ELF3 and ATF4 transcriptional axis programs the amino acid insufficiency-linked epithelial-to-mesenchymal transition

Epithelial-to-mesenchymal transition (EMT) that endows cancer cells with increased invasive and migratory capacity enables cancer dissemination and metastasis. This process is tightly associated with metabolic reprogramming acquired for rewiring cell status and signaling pathways for survival in dietary insufficiency conditions. However, it remains largely unclear how transcription factor (TF)-mediated transcriptional programs are modulated during the EMT process. Here, we reveal that depletion of a key epithelial TF, ELF3 (E74-like factor-3), triggers a transforming growth factor β (TGF-β) signaling activation-like mesenchymal transcriptomic profile and metastatic features linked to the aminoacyl-tRNA biogenesis pathway. Moreover, the transcriptome alterations elicited by ELF3 depletion perfectly resemble an ATF4-dependent weak response to amino acid starvation. Intriguingly, we observe an exclusive enrichment of ELF3 and ATF4 in epithelial and TGF-β-induced or ELF3-depletion-elicited mesenchymal enhancers, respectively, with rare co-binding on altered enhancers. We also find that the upregulation of aminoacyl-tRNA synthetases and some mesenchymal genes upon amino acid deprivation is diminished in ATF4-depleted cells. In sum, the loss of ELF3 binding on epithelial enhancers and the gain of ATF4 binding on the enhancers of mesenchymal factors and amino acid deprivation responsive genes facilitate the loss of epithelial cell features and the gain of TGF-β-signaling-associated mesenchymal signatures, which further promote lung cancer cell metastasis.

Inhibition of asparagine synthetase effectively retards polycystic kidney disease progression

Polycystic kidney disease (PKD) is a genetic disorder characterized by bilateral cyst formation. We showed that PKD cells and kidneys display metabolic alterations, including the Warburg effect and glutaminolysis, sustained in vitro by the enzyme asparagine synthetase (ASNS). Here, we used antisense oligonucleotides (ASO) against Asns in orthologous and slowly progressive PKD murine models and show that treatment leads to a drastic reduction of total kidney volume (measured by MRI) and a prominent rescue of renal function in the mouse. Mechanistically, the upregulation of an ATF4-ASNS axis in PKD is driven by the amino acid response (AAR) branch of the integrated stress response (ISR). Metabolic profiling of PKD or control kidneys treated with Asns-ASO or Scr-ASO revealed major changes in the mutants, several of which are rescued by Asns silencing in vivo. Indeed, ASNS drives glutamine-dependent de novo pyrimidine synthesis and proliferation in cystic epithelia. Notably, while several metabolic pathways were completely corrected by Asns-ASO, glycolysis was only partially restored. Accordingly, combining the glycolytic inhibitor 2DG with Asns-ASO further improved efficacy. Our studies identify a new therapeutic target and novel metabolic vulnerabilities in PKD.