Metabolic Blockade Research Articles

Metal-Organic Nanomaterials for Tumor Metabolic Blockade and Image to Increase Tumor Therapy.

The abnormal energy metabolism level of a tumor reduces the efficiency of chemotherapy. Metal-organic nanomaterials (MONs) with high drug loading efficiency, easy processes of synthesis, and controlled drug release have shown great potential in metabolic blocking and enhancement of tumor therapy. These metal-organic nanomedicines have been reported to modulate glycolysis or oxidative phosphorylation to provide monotherapy or combined therapies in tumorous treatments. In addition, the encapsulation or coordination of fluorescent dyes into MONs endowed them with the imaging ability of tumor metabolism. Herein, this Perspective summarizes the progress of MONs as therapeutic agents or imaging probes for application during tumor metabolic blocking or imaging, providing solid inspiration for biomedical applications of effective biomaterials. In addition, the current drawbacks of MONs for further biological applications in the future were discussed, giving stimulation of innovation and development in biomedical applications of MONs.

Exploring fructose metabolism as a potential therapeutic approach for pancreatic cancer.

Excessive fructose intake has been associated with the development and progression of pancreatic cancer. This study aimed to elucidate the relationship between fructose utilization and pancreatic cancer progression. Our findings revealed that pancreatic cancer cells have a high capacity to utilize fructose and are capable of converting glucose to fructose via the AKR1B1-mediated polyol pathway, in addition to uptake via the fructose transporter GLUT5. Fructose metabolism exacerbates pancreatic cancer proliferation by enhancing glycolysis and accelerating the production of key metabolites that regulate angiogenesis. However, pharmacological blockade of fructose metabolism has been shown to slow pancreatic cancer progression and synergistically enhance anti-tumor capabilities when combined with anti-angiogenic agents. Overall, targeting fructose metabolism may prove to be a promising therapeutic approach in the treatment of pancreatic cancer.

Inhibition of DUSP18 impairs cholesterol biosynthesis and promotes anti-tumor immunity in colorectal cancer

Tumor cells reprogram their metabolism to produce specialized metabolites that both fuel their own growth and license tumor immune evasion. However, the relationships between these functions remain poorly understood. Here, we report CRISPR screens in a mouse model of colo-rectal cancer (CRC) that implicates the dual specificity phosphatase 18 (DUSP18) in the establishment of tumor-directed immune evasion. Dusp18 inhibition reduces CRC growth rates, which correlate with high levels of CD8+ T cell activation. Mechanistically, DUSP18 dephosphorylates and stabilizes the USF1 bHLH-ZIP transcription factor. In turn, USF1 induces the SREBF2 gene, which allows cells to accumulate the cholesterol biosynthesis intermediate lanosterol and release it into the tumor microenvironment (TME). There, lanosterol uptake by CD8+ T cells suppresses the mevalonate pathway and reduces KRAS protein prenylation and function, which in turn inhibits their activation and establishes a molecular basis for tumor cell immune escape. Finally, the combination of an anti-PD-1 antibody and Lumacaftor, an FDA-approved small molecule inhibitor of DUSP18, inhibits CRC growth in mice and synergistically enhances anti-tumor immunity. Collectively, our findings support the idea that a combination of immune checkpoint and metabolic blockade represents a rationally-designed, mechanistically-based and potential therapy for CRC.

A genome-wide CRISPR screen reveals that antagonism of glutamine metabolism sensitizes head and neck squamous cell carcinoma to ferroptotic cell death

Glutamine is a conditionally essential amino acid for the growth and survival of rapidly proliferating cancer cells. Many cancers are addicted to glutamine, and as a result, targeting glutamine metabolism has been explored clinically as a therapeutic approach. Glutamine-catalyzing enzymes are highly expressed in primary and metastatic head and neck squamous cell carcinoma (HNSCC). However, the nature of the glutamine-associated pathways in this aggressive cancer type has not been elucidated. Here, we explored the therapeutic potential of a broad glutamine antagonist, DRP-104 (sirpiglenastat), in HNSCC tumors and aimed at shedding light on glutamine-dependent pathways in this disease. We observed a potent antitumoral effect of sirpiglenastat in HPV- and HPV + HNSCC xenografts. We conducted a whole-genome CRISPR screen and metabolomics analyses to identify mechanisms of sensitivity and resistance to glutamine metabolism blockade. These approaches revealed that glutamine metabolism blockade results in the rapid buildup of polyunsaturated fatty acids (PUFAs) via autophagy nutrient-sensing pathways. Finally, our analysis demonstrated that GPX4 mediates the protection of HNSCC cells from accumulating toxic lipid peroxides; hence, glutamine blockade sensitizes HNSCC cells to ferroptosis cell death upon GPX4 inhibition. These findings demonstrate the therapeutic potential of sirpiglenastat in HNSCC and establish a novel link between glutamine metabolism and ferroptosis, which may be uniquely translated into targeted glutamine-ferroptosis combination therapies.

Mitochondrial metabolism blockade nanoadjuvant reversed immune-resistance microenvironment to sensitize albumin-bound paclitaxel-based chemo-immunotherapy

Currently, the efficacy of albumin-bound paclitaxel (PTX@Alb) is still limited due to the impaired PTX@Alb accumulation in tumors partly mediated by the dense collagen distribution. Meanwhile, acquired immune resistance always occurs due to the enhanced programmed cell death-ligand 1 (PD-L1) expression after PTX@Alb treatment, which then leads to immune tolerance. To fill these gaps, we newly revealed that tamoxifen (TAM), a clinically widely used adjuvant therapy for breast cancer with mitochondrial metabolism blockade capacity, could also be used as a novel effective PD-L1 and TGF-β dual-inhibitor via inducing the phosphorylation of adenosine 5ʹ-monophosphate-activated protein kinase (AMPK) protein. Following this, to obtain a more significant effect, TPP-TAM was prepared by conjugating mitochondria-targeted triphenylphosphine (TPP) with TAM, which then further self-assembled with albumin (Alb) to form TPP-TAM@Alb nanoparticles. By doing this, TPP-TAM@Alb nanoparticles effectively decreased the expression of collagen in vitro, which then led to the enhanced accumulation of PTX@Alb in 4T1 tumors. Besides, TPP-TAM@Alb also effectively decreased the expression of PD-L1 and TGF-β in tumors to better sensitize PTX@Alb-mediated chemo-immunotherapy by enhancing T cell infiltration. All in all, we newly put forward a novel mitochondrial metabolism blockade strategy to inhibit PTX@Alb-resistant tumors, further supporting its better clinical application.

P53 activation enhances the sensitivity of non-small cell lung cancer to the combination of SH003 and docetaxel by inhibiting de novo pyrimidine synthesis

BackgroundIdentifying molecular biomarkers for predicting responses to anti-cancer drugs can enhance treatment precision and minimize side effects. This study investigated the novel cancer-targeting mechanism of combining SH003, an herbal medicine, with docetaxel in non-small cell lung cancer (NSCLC) cells. Also, the present study aimed to identify the genetic characteristics of cancer cells susceptible to this combination.MethodsCell viability was analyzed by WST-8 assay. Apoptosis induction, BrdU incorporation, and cell cycle analysis were performed using flow cytometry. Metabolites were measured by LC–MS/MS analysis. Real-time PCR and western blotting evaluated RNA and protein expression. DNA damage was quantified through immunofluorescence. cBioPortal and GEPIA data were utilized to explore the mutual co-occurrence of TP53 and UMPS and UMPS gene expression in NSCLC.ResultsThe combination treatment suppressed de novo pyrimidine nucleotide biosynthesis by reducing the expression of related enzymes. This blockade of pyrimidine metabolism led to DNA damage and subsequent apoptosis, revealing a novel mechanism for inducing lung cancer cell death with this combination. However, some lung cancer cells exhibited distinct responses to the combination treatment that inhibited pyrimidine metabolism. The differences in sensitivity in lung cancer cells were determined by the TP53 gene status. TP53 wild-type lung cancer cells were effectively inhibited by the combination treatment through p53 activation, while TP53 mutant- or null-type cells exhibited lower sensitivity.ConclusionsThis study, for the first time, established a link between cancer cell genetic features and treatment response to simultaneous SH003 and docetaxel treatment. It highlights the significance of p53 as a predictive factor for susceptibility to this combination treatment. These findings also suggest that p53 status could serve as a crucial criterion in selecting appropriate therapeutic strategies for targeting pyrimidine metabolism in lung cancer.

Potassium ion efflux induces exaggerated mitochondrial damage and non-pyroptotic necrosis when energy metabolism is blocked

Damage-associated molecular patterns (DAMPs) such as extracellular ATP and nigericin (a bacterial toxin) not only act as potassium ion (K+) efflux inducers to activate NLRP3 inflammasome, leading to pyroptosis, but also induce cell death independently of NLRP3 expression. However, the roles of energy metabolism in determining NLRP3-dependent pyroptosis and -independent necrosis upon K+ efflux are incompletely understood. Here we established cellular models by pharmacological blockade of energy metabolism, followed by stimulation with a K+ efflux inducer (ATP or nigericin). Two energy metabolic inhibitors, namely CPI-613 that targets α-ketoglutarate dehydrogenase and pyruvate dehydrogenase (a rate-limiting enzyme) and 2-deoxy-d-glucose (2-DG) that targets hexokinase, are recruited in this study, and Nlrp3 gene knockout macrophages were used. Our data showed that CPI-613 and 2-DG dose-dependently inhibited NLRP3 inflammasome activation, but profoundly increased cell death in the presence of ATP or nigericin. The cell death was K+ efflux-induced but NLRP3-independent, which was associated with abrupt reactive oxygen species (ROS) production, reduction of mitochondrial membrane potential, and oligomerization of mitochondrial proteins, all indicating mitochondrial damage. Notably, the cell death induced by K+ efflux and blockade of energy metabolism was distinct from pyroptosis, apoptosis, necroptosis or ferroptosis. Furthermore, fructose 1,6-bisphosphate, a high-energy intermediate of glycolysis, significantly suppressed CPI-613+nigericin-induced mitochondrial damage and cell death. Collectively, our data show that energy deficiency diverts NLRP3 inflammasome activation-dependent pyroptosis to Nlrp3-independent necrosis upon K+ efflux inducers, which can be dampened by high-energy intermediate, highlighting a critical role of energy metabolism in cell survival and death under inflammatory conditions.

Azo-based hypoxic-activated 6-diazo-5-oxo-L-norleucine (DON) prodrug combined with vascular disrupting agent nanoparticles for tumor-selective glutamine metabolism blockade

Glutamine antagonists, such as 6-diazo-5-oxo-L-norleucine (DON), have demonstrated remarkable anti-tumor effects by blocking tumor glutamine metabolism, but their use is frequently causing toxicity. Despite the existence of multiple glutamine antagonist prodrug designs, a tumor-selective prodrug has yet to be developed. Herein, a novel prodrug of DON, Azo-DON, has been developed, which remains stable and inactive in normal tissues with sufficient oxygen levels, while can be selectively reduced to DON by highly expressed azo-reductase in hypoxic tumor environments. This leads to blockade of glutamine metabolism in cancer cells and promotes cell death without affecting T cell proliferation. In a high-hypoxic H22 hepatoma cancer model, Azo-DON showed a 1.8-fold enhancement in glutamine blockade compared to the control group, resulting in a tumor suppression rate (TSR) of 84.2% in vivo with no significant weight loss. In a low-hypoxic CT26 colon cancer model, when combined with vascular disrupting agent nanoparticles (CBP) to induce a hypoxic environment, Azo-DON exhibited a 4.6-fold enhancement in glutamine blockade over the control group, resulted in a remarkable TSR of 96.6% in vivo. This innovative approach represents a promising strategy for the application of broad-spectrum metabolic inhibitors in the field of precision cancer treatment.

Hypoxia-activated glutamine antagonist prodrug combined with combretastatin A4 nanoparticles for tumor-selective metabolic blockade

6-Diazo-5-oxo-L-norleucine (DON) is a potent glutamine antagonist with toxic side effects; in order to reduce these effects, multiple prodrugs have been designed. However, there are currently no reports of a DON prodrug with a defined mechanism to achieve high tumor selectivity. To improve the selective toxicity of DON to tumor cells while reducing systemic toxicity, a hypoxia-activated prodrug, termed HDON, was designed. HDON achieved remarkable tumor suppression of 76.4 ± 5.2% without leading to weight loss in an H22 murine liver cancer model with high hypoxia. Moreover, to augment the therapeutic efficacy of HDON, combretastatin A4 nanoparticles were used to aggravate tumor hypoxia of MC38 murine colon cancer and 4T1 murine breast cancer, activate HDON to DON, and stimulate a robust anti-tumor immune response while selectively killing in tumor cells in vivo, achieving significantly elevated tumor suppression rates of 98.3 ± 3.4% and 98.1 ± 3.1%, with cure rates of 80.0% and 20.0%, respectively.

Metal organic frameworks based intelligent nanoadjuvants for boosting tumor immunotherapy through enhanced ICD and lactic acid regulation

Immunotherapy has been considered as a potent antitumor modality while its efficacy is frequently hampered by the insufficient immunogenicity and immunosuppressive tumor microenvironment (TME) with overexpressed lactic acid (LA). Herein, an intelligent nanoadjuvant MOF@LOD-siRNA@Lips-FA (MLSLF) was developed by loading lactate oxidase (LOD) and monocarboxylate transporter 4 (MCT4)-inhibiting siRNA into Fe-MOF and further coated with folate-liposomes (FA-lip) for enhanced immunotherapy. The MLSLF could response to endogenous glutathione (GSH), resulting in the depletion of GSH and production of •OH for effective chemodynamic therapy (CDT). On one hand, the death of cancer cells would arouse immunogenic cell death (ICD) to release antigens and enhance tumor immunogenicity. Meanwhile, LOD could decompose intracellular LA to H2O2, which could further promote ICD and boost anti-tumor immune response. On the other hand, the siRNA could restrict the expression of MCT4, which would hinder the intracellular LA efflux. The combination of LOD and siRNA could reduce the LA content in TME and relieve immunosuppression TME. The in vivo results revealed that MLSLF could effectually suppress the growth of primary and distant tumors in tumor-bearing mice. Therefore, the smart MLSLF could be a synergistic anti-tumor strategy for efficient immunotherapy through the combination of enhanced ICD and LA metabolism blockade.

Blockade of Arf1-mediated lipid metabolism in cancers promotes tumor infiltration of cytotoxic T cells via the LPE-PPARγ-NF-κB-CCL5 pathway

Abstract Tumor immunotherapy has achieved breakthroughs in a variety of tumors. However, the systemic absence of T cells in tumors and immunosuppressive tumor microenvironment so far limits the efficacy of immunotherapy to a small population of patients. Therefore, novel agents to increase T-cell tumor infiltration are urgently needed in the clinic. We recently found that inhibition of the ADP-ribosylation factor 1 (Arf1)-mediated lipid metabolism not only kills cancer stem cells (CSCs) but also elicits an anti-tumor immune response. In this study, we revealed a mechanism that targeting Arf1 promotes the infiltration of cytotoxic T lymphocytes (CTLs) into tumors through the C-C chemokine ligand 5 (CCL5)- C-C chemokine receptor type 5 (CCR5) pathway. We found that blockage of Arf1 induces the production of the unsaturated fatty acid (PE 18:1) that binds and sequestrates peroxisome proliferator-­activated receptor-γ (PPARγ) from the PPARγ-nuclear factor-κB (NF-κB) cytoplasmic complex. The released NF-κB was then phosphorylated and translocated into the nucleus to regulate the transcription of chemokine CCL5. CCL5 promoted infiltration of CTLs for tumor regression. Furthermore, the combination of the Arf1 inhibitor and programmed cell death protein 1 (PD-1) blockade induced an even stronger anti-tumor immunity. Therefore, targeting Arf1 represents a novel anti-tumor immune approach by provoking T-cell tumor infiltration and may provide a new strategy for tumor immunotherapy.

Intravascular hemolysis triggers NAFLD characterized by a deregulation of lipid metabolism and lipophagy blockade.

Intravascular hemolysis is a common feature of different clinical entities, including sickle cell disease and malaria. Chronic hemolytic disorders are associated with hepatic damage; however, it is unknown whether heme disturbs lipid metabolism and promotes liver steatosis, thereby favoring the progression to nonalcoholic fatty liver disease (NAFLD). Using an experimental model of acute intravascular hemolysis, we report here the presence of liver injury in association with microvesicular lipid droplet deposition. Hemolysis promoted serum hyperlipidemia and altered intrahepatic triglyceride fatty acid composition, with increments in oleic, palmitoleic, and palmitic acids. These findings were related to augmented expression of transporters involved in fatty acid uptake (CD36 and MSR1) and deregulation of LDL transport, as demonstrated by decreased levels of LDL receptor and increased PCSK9 expression. Hemolysis also upregulated hepatic enzymes associated with cholesterol biosynthesis (SREBP2, HMGC1, LCAT, SOAT1) and transcription factors regulating lipid metabolism (SREBP1). Increased LC3II/LC3I ratio and p62/SQSTM1 protein levels were reported in mice with intravascular hemolysis and hepatocytes stimulated with heme, indicating a blockade of lipophagy. In cultured hepatocytes, cell pretreatment with the autophagy inductor rapamycin diminished heme-mediated toxicity and accumulation of lipid droplets. In conclusion, intravascular hemolysis enhances liver damage by exacerbating lipid accumulation and blocking the lipophagy pathway, thereby promoting NAFLD. These new findings have a high translational potential as a novel NAFLD-promoting mechanism in individuals suffering from severe hemolysis episodes. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Lysosome blockade induces divergent metabolic programs in macrophages and tumours for cancer immunotherapy

BackgroundPlatinum-drugs based chemotherapy in clinic increases the potency of tumor cells to produce M2 macrophages, thus leading to poor anti-metastatic activity and immunosuppression. Lysosome metabolism is critical for cancer cell migration and invasion, but how it promotes antitumor immunity in tumours and macrophages is poorly understood and the underlying mechanisms are elusive. The present study aimed to explore a synergistic strategy to dismantle the immunosuppressive microenvironment of tumours and metallodrugs discovery by using the herent metabolic plasticity.MethodsNaphplatin was prepared by coordinating an active alkaline moiety to cisplatin, which can regulate the lysosomal functions. Colorectal carcinoma cells were selected to perform the in vivo biological assays. Blood, tumour and spleen tissues were collected and analyzed by flow cytometry to further explore the relationship between anti-tumour activity and immune cells. Transformations of bone marrow derived macrophage (BMDM) and M2-BMDM to the M1 phenotype was confirmed after treatment with naphplatin. The key mechanisms of lysosome-mediated mucolipin-1(Mcoln1) and mitogen-activated protein kinase (MAPK) activation in M2 macrophage polarization have been unveiled. RNA sequencing (RNA-seq) was used to further explore the key mechanism underlying high-mobility group box 1(HMGB1)-mediated Cathepsin L(CTSL)-lysosome function blockade.ResultsWe demonstrated that naphplatin induces divergent lysosomal metabolic programs and reprograms macrophages in tumor cells to terminate the vicious tumour-associated macrophages (TAMs)-MDSCs-Treg triangle. Mechanistically, macrophages treated with naphplatin cause lysosome metabolic activation by triggering Ca2+ release via Mcoln1, which induces the activation of p38 and nuclear factor-κB (NF-κB) and finally results in polarizing M2 macrophages. In contrast, HMGB1-mediated lysosome metabolic blockade in cancer cells is strongly linked to antitumor effects by promoting cytoplasmic translocation of HMGB1.ConclusionsThis study reveals the crucial strategies of macrophage-based metallodrugs discovery that are able to treat both immunologically “hot” and “cold” cancers. Different from traditional platinum-based antitumour drugs by inhibition of DNAs, we also deliver a strong antitumour strategy by targeting lysosome to induce divergent metabolic programs in macrophages and tumours for cancer immunotherapy.

Reduction of Proinflammatory Effector Functions Through Remodeling of Fatty Acid Metabolism in CD8+ T Cells From Rheumatoid Arthritis Patients.

Rheumatoid arthritis (RA) CD8+ T cells maintain their effector proinflammatory phenotype by changing their metabolism toward aerobic glycolysis. However, their massive energy and biosynthesis needs may require additional substrates other than glucose. Since systemic alterations in lipid metabolism have been reported in RA patients, we explored the role of fatty acid (FA) metabolism in CD8+ T cells to identify potential targets to curb their proinflammatory potential. The expression of FA metabolism-related genes was analyzed for total CD8+ T cells and CD8+ T cell subsets in the data of RA patients and healthy controls retrieved from the GEO database. Functional assays were performed using peripheral blood CD8+ T cells isolated from RA (n=31), psoriatic arthritis (n=26), and spondyloarthritis (n=21) patients receiving different therapies (disease-modifying antirheumatic drugs, biologics, and JAK inhibitors) and from healthy controls (n=14). We quantified the expression of FA transporters, lipid uptake, intracellular FA content, cytokine production, activation, proliferation, and capacity to inhibit tumor cell growth, either with or without FA metabolism inhibitors. The CD8+ T cell gene expression profile of FA metabolism-related genes was significantly different between untreated RA patients and healthy controls. RA patients who had a good clinical response after 6 months of methotrexate therapy had significantly increased expression of FA metabolism-related genes. Cell surface expression of the FA transporters FA binding protein 4 (FABP4) and G protein-coupled receptor 84 (GPR84) and FA uptake were higher in effector and memory CD8+ T cells from RA patients compared to those from healthy controls. In vitro blockade of FA metabolism significantly impaired CD8+ T cell effector functions. RA CD8+ T cells present an altered FA metabolism, which could provide potential therapeutic targets to control their proinflammatory profile, particularly therapies directed against the transport and oxidation of free FA.

In vivo evaluation of the effect of sickle cell hemoglobin S, C and therapeutic transfusion on erythrocyte metabolism and cardiorenal dysfunction.

Despite a wealth of exploratory plasma metabolomics studies in sickle cell disease (SCD), no study to date has evaluate a large and well phenotyped cohort to compare the primary erythrocyte metabolome of hemoglobin SS, SC and transfused AA red blood cells (RBCs) in vivo. The current study evaluates the RBC metabolome of 587 subjects with sickle cell sickle cell disease (SCD) from the WALK-PHaSST clinical cohort. The set includes hemoglobin SS, hemoglobin SC SCD patients, with variable levels of HbA related to RBC transfusion events. Here we explore the modulating effects of genotype, age, sex, severity of hemolysis, and transfusion therapy on sickle RBC metabolism. Results show that RBCs from patients with Hb SS genotypes-compared to AA RBCs from recent transfusion events or SC RBCs-are characterized by significant alterations of RBC acylcarnitines, pyruvate, sphingosine 1-phosphate, creatinine, kynurenine and urate metabolism. Surprisingly, the RBC metabolism of SC RBCs is dramatically different from SS, with all glycolytic intermediates significantly elevated in SS RBCs, with the exception of pyruvate. This result suggests a metabolic blockade at the ATP-generating phosphoenolpyruvate to pyruvate step of glycolysis, which is catalyzed by redox-sensitive pyruvate kinase. Metabolomics, clinical and hematological data were collated in a novel online portal. In conclusion, we identified metabolic signatures of HbS RBCs that correlate with the degree of steady state hemolytic anemia, cardiovascular and renal dysfunction and mortality.

Heterostructural Nanoadjuvant CuSe/CoSe2 for Potentiating Ferroptosis and Photoimmunotherapy through Intratumoral Blocked Lactate Efflux.

The desirable curative effect in clinical immunotherapy has been challenging due to the immunosuppressive tumor microenvironment (TME) with high lactic acid (LA) metabolism in solid tumors. Although targeting metabolic reprogramming of tumor cells can restore the survival and function of immune cells in the TME, it is also plagued by insufficient immunogenicity. Herein, an activatable immunomodulatory nanoadjuvant CuSe/CoSe2@syrosingopine (CSC@Syro) is constructed for simultaneously relieving immunosuppressive TME and boosting tumor immune response. Specifically, CuSe/CoSe2 (CSC) exhibits TME-activated glutathione (GSH) depletion and hydroxyl radical (•OH) generation for potential ferroptosis. Meanwhile, the remarkable photothermal conversion efficiency and elevated photocatalytic ROS level both promote CSC heterostructures to induce robust immunogenic cell death (ICD). Besides, the loaded syrosingopine inhibitor achieves LA metabolism blockade in cancer cells by downregulating the expression of monocarboxylate transporter 4 (MCT4), which could sensitize ferroptosis by intracellular milieu acidification and neutralize the acidic TME to alleviate immunosuppression. Hence, advanced metabolic modulation confers the potentiated immune infiltration of ICD-stimulated T lymphocytes and further reinforces antitumor therapy. In brief, CSC@Syro-mediated synergistic therapy could elicit potent immunogenicity and suppress tumor proliferation and metastasis effectually by integrating the tumor metabolic regulation and ferroptosis with immunotherapy.

Feasibility of [18F]FSPG PET for Early Response Assessment to Combined Blockade of EGFR and Glutamine Metabolism in Wild-Type KRAS Colorectal Cancer.

Early response assessment is critical for personalizing cancer therapy. Emerging therapeutic regimens with encouraging results in the wild-type (WT) KRAS colorectal cancer (CRC) setting include inhibitors of epidermal growth factor receptor (EGFR) and glutaminolysis. Towards predicting clinical outcome, this preclinical study evaluated non-invasive positron emission tomography (PET) with (4S)-4-(3-[18F]fluoropropyl)-L-glutamic acid ([18F]FSPG) in treatment-sensitive and treatment-resistant WT KRAS CRC patient-derived xenografts (PDXs). Tumor-bearing mice were imaged with [18F]FSPG PET before and one week following the initiation of treatment with either EGFR-targeted monoclonal antibody (mAb) therapy, glutaminase inhibitor therapy, or the combination. Imaging was correlated with tumor volume and histology. In PDX that responded to therapy, [18F]FSPG PET was significantly decreased from baseline at 1-week post-therapy, prior to changes in tumor volume. In contrast, [18F]FSPG PET was not decreased in non-responding PDX. These data suggest that [18F]FSPG PET may serve as an early metric of response to EGFR and glutaminase inhibition in the WT KRAS CRC setting.

Sphingomyelin metabolism underlies Ras excitability for efficient cell migration and chemotaxis.

In eukaryotic motile cells, the active Ras (Ras-GTP)-enriched domain is generated in an asymmetric manner on the cell membrane through the excitable dynamics of an intracellular signaling network. This asymmetric Ras signaling regulates pseudopod formation for both spontaneous random migration and chemoattractant-induced directional migration. While membrane lipids, such as sphingomyelin and phosphatidylserine, contribute to Ras signaling in various cell types, whether they are involved in the Ras excitability for cell motility is unknown. Here we report that functional Ras excitability requires the normal metabolism of sphingomyelin for efficient cell motility and chemotaxis. The pharmacological blockade of sphingomyelin metabolism by an acid-sphingomyelinase inhibitor, fendiline, and other inhibitors suppressed the excitable generation of the stable Ras-GTP-enriched domain. The suppressed excitability failed to invoke enough basal motility to achieve directed migration under shallow chemoattractant gradients. The fendiline-induced defects in Ras excitability, motility and stimulation-elicited directionality were due to an accumulation of sphingomyelin on the membrane, which could be recovered by exogenous sphingomyelinase or phosphatidylserine without changing the expression of Ras. These results indicate a novel regulatory mechanism of the excitable system by membrane lipids, in which sphingomyelin metabolism provides a membrane environment to ensure Ras excitation for efficient cellular motility and chemotaxis.Key words: cell polarity, cell migration, Ras, excitability, sphingomyelin.

A core-satellite micellar system against primary tumors and their lymphatic metastasis through modulation of fatty acid metabolism blockade and tumor-associated macrophages.

Lymph nodes (LNs) are the initial sanctuary of various metastatic tumor cells, and thus a precise lymphatic drug delivery strategy is necessary for the effective inhibition of metastasis. However, the complex biological barriers have restrained the drug delivery to tumor-draining lymph nodes (TDLNs). Metastatic tumor cells would undergo metabolic adaptation towards fatty acid oxidation (FAO) upon reaching the lipid-rich LNs. Herein, to inhibit primary tumors and their lymphatic metastasis, a core-satellite matrix metalloproteinase 2 (MMP-2) responsive micellar system was developed for sequential delivery of paclitaxel (PTX) and the metabolism-regulating drug etomoxir (ET) to tumors and TDLNs, respectively. Upon arrival at the tumor microenvironment (TME), the small satellite micelle encapsulating ET was detached from the core micelle in response to MMP-2, which not only drained to TDLNs via tumor-draining lymphatic vessels and inhibited the FAO of metastatic tumor cells, but also blocked M2-like macrophage polarization in the TME. Meanwhile, the core micelle containing PTX could largely accumulate in the TME and kill tumor cells. In an orthotopic 4T1 breast cancer model, the tumor and TDLN dual-targeted core-satellite micellar system effectively inhibited the growth of the primary tumor and alleviated immune suppression by blocking macrophage polarization. More importantly, tumor lymphatic metastasis was suppressed through FAO metabolic regulation. This strategy provides a promising approach for TDLN targeted therapy against breast cancer and its lymphatic metastasis.

Muscle glycogen unavailability and fat oxidation rate during exercise: Insights from McArdle disease.

Carbohydrate availability affects fat metabolism during exercise; however, the effects of complete muscle glycogen unavailability on maximal fat oxidation (MFO) rate remain unknown. Our purpose was to examine the MFO rate in patients with McArdle disease, comprising an inherited condition caused by complete blockade of muscle glycogen metabolism, compared to healthy controls. Nine patients (three women, aged 36±12 years) and 12healthy controls (four women, aged 40±13 years) were studied. Several molecular markers of lipid transport/metabolism were also determined in skeletal muscle (gastrocnemius) and white adipose tissue of McArdle (Pygm p.50R*/p.50R*) and wild-type male mice. Peak oxygen uptake ( ), MFO rate, the exercise intensity eliciting MFO rate (FATmax) and the MFO rate-associated workload were determined by indirect calorimetry during an incremental cycle-ergometer test. Despite having a much lower (24.7±4 vs. 42.5±11.4mLkg-1 min-1 , respectively; P<0.0001), patients showed considerably higher values for the MFO rate (0.53±0.12 vs. 0.33±0.10 gmin-1 , P=0.001), and for the FATmax (94.4±7.2 vs. 41.3±9.1 % of , P<0.0001) and MFO rate-associated workload (1.33±0.35 vs. 0.81±0.54Wkg-1 , P=0.020) than controls. No between-group differences were found overall in molecular markers of lipid transport/metabolism in mice. In summary, patients with McArdle disease show an exceptionally high MFO rate, which they attained at near-maximal exercise capacity. Pending more mechanistic explanations, these findings support the influence of glycogen availability on MFO rate and suggest that these patients develop a unique fat oxidation capacity, possibly as an adaptation to compensate for the inherited blockade in glycogen metabolism, and point to MFO rate as a potential limiting factor of exercise tolerance in this disease. KEY POINTS: Physically active McArdle patients show an exceptional fat oxidation capacity. Maximal fat oxidation rate occurs near-maximal exercise capacity in these patients. McArdle patients' exercise tolerance might rely on maximal fat oxidation rate capacity. Hyperpnoea might cloud substrate oxidation measurements in some patients. An animal model revealed overall no higher molecular markers of lipid transport/metabolism.