Metabolic Rewiring Research Articles

Sweet dreams could be made of this: carbohydrate-responsive element-binding protein (ChREBP) as a target for hepatocellular carcinoma therapy.

Rewiring of cellular metabolism is now fully recognized as a hallmark of cancer. Tumor cells reprogram metabolic pathways to meet the energetic and macromolecular demands to support unrestricted growth and survival under unfavorable conditions. It is becoming apparent that these adaptations underpin most of the traits that define a cancer cell's identity, including the ability to avoid immune surveillance, endure nutrient and oxygen restrictions, detach and migrate from their natural histological niche, and avert human-made aggressions (i.e., therapy). In a recent study, Benichou and collaborators identify carbohydrate-responsive element-binding protein (ChREBP), a master regulator of physiological glucose metabolism, as an oncogene in hepatocellular carcinoma (HCC) development. Upregulation of ChREBP expression results in a self-stimulatory loop interconnecting PI3K/AKT signaling and glucose metabolism to feed fatty acid and nucleotide synthesis supporting tumorigenesis. Importantly, pharmacological inhibition of ChREBP activity quells in vivo HCC tumor growth without causing systemic toxicity. This study identifies novel oncometabolic pathways and open up new avenues to improve the treatment of a deadly tumor.

Unravelling the metabolic rewiring in the context of doxorubicin-induced cardiotoxicity: Fuel preference changes from fatty acids to glucose oxidation

Doxorubicin (DOX) is a highly effective chemotherapeutic agent whose clinical use is hindered by the onset of cardiotoxic effects, resulting in reduced ejection fraction within the first year from treatment initiation. Recently it has been demonstrated that DOX accumulates within mitochondria, leading to disruption of metabolic processes and energetic imbalance. We previously described that phosphoinositide 3-kinase γ (PI3Kγ) contributes to DOX-induced cardiotoxicity, causing autophagy inhibition and accumulation of damaged mitochondria. Here we intend to describe the maladaptive metabolic rewiring occurring in DOX-treated hearts and the contribution of PI3Kγ signalling to this process. Metabolomic analysis of DOX-treated WT hearts revealed an accumulation of TCA cycle metabolites due to a cycle slowdown, with reduced levels of pyruvate, unchanged abundance of lactate and increased Acetyl-CoA production. Moreover, the activity of glycolytic enzymes was upregulated, and fatty acid oxidation downregulated, after DOX, indicative of increased glucose oxidation. In agreement, oxygen consumption was increased in after pyruvate supplementation, with the formation of cytotoxic ROS rather than energy production. These metabolic changes were fully prevented in KD hearts. Interestingly, they failed to increase glucose oxidation in response to DOX even with autophagy inhibition, indicating that PI3Kγ likely controls the fuel preference after DOX through an autophagy-independent mechanism. In vitro experiments showed that inhibition of PI3Kγ inhibits pyruvate dehydrogenase (PDH), the key enzyme of Randle cycle regulating the switch from fatty acids to glucose usage, while decreasing DOX-induced mobilization of GLUT-4-carrying vesicles to the plasma membrane and limiting the ensuing glucose uptake. These results demonstrate that PI3Kγ promotes a maladaptive metabolic rewiring in DOX-treated hearts, through a two-pronged mechanism controlling PDH activation and GLUT-4-mediated glucose uptake.

Exploring the mechanisms of metabolic adaptations to cardiotoxic doxorubicin

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Leducq Foundation Background Doxorubicin (DOX) is an anthracycline chemotherapeutic agent whose clinical application is hindered by the emergence of early and late cardiotoxic effects. Recent findings demonstrated that DOX damages cardiac mitochondria, with subsequent metabolic perturbation and energetic imbalance. We previously observed that phosphoinositide 3-kinase γ (PI3Kγ) contributes to DOX-induced cardiotoxicity, mediating mitophagy inhibition and accumulation of damaged mitochondria into cardiac cells. Objective Here we intend to describe the cardiotoxic metabolic phenotype of DOX-treated hearts, unravelling the contribution of PI3Kγ signalling to this process. Methods Wild-type (WT) and knock-in mice expressing a kinase-inactive PI3Kγ (kinase-dead; KD) were treated with DOX at day 0, 7 and 14 (cumulative dose 12 mg/kg). To explore the contribution of PI3Kγ on the early cardiac metabolic rewiring, metabolomic analysis, mitochondrial respiration capacity and glycolytic enzymes activity were evaluated at day 3. To investigate the role of autophagy, mice were infected with an adeno-associated virus 9 (AAV9) carrying a vector expressing a short-hairpin RNA against ATG7 (ATG7sh). To test the role of PI3Kγ in glycolysis regulation, glucose uptake and plasma membrane exposure of GLUT-4 were measured in neonatal mouse cardiomyocytes with DOX acute treatment (1µM for 3h). To evaluate the contribution of different substrates to oxygen consumption, OROBOROS analysis were performed on myocardial slices from mice sacrificed at day 3 and 42. Results DOX-treated cardiomyocytes exhibited a metabolic phenotype characterized by glucose as the primary energy substrate, with increased uptake and augmented glycolytic enzymes activity. Metabolomic analysis of DOX-treated hearts indicated diminished pyruvate levels, the glycolysis end-product, unaltered lactate but increased Acetyl-CoA quantity, suggesting enhanced glucose processing for the TCA cycle. Accordingly, oxygen consumption after pyruvate supplementation significantly increased in DOX-treated condition, resulting in the generation of cytotoxic ROS rather than energy production. This was mainly due to DOX-induced mitochondrial damage, with impaired fatty acid oxidation and electron transport chain activity, resulting in TCA cycle slow-down, with accumulation of cardiotoxic glucose-derived intermediates. These metabolic alterations were completely prevented in KD hearts. In vitro experiments demonstrated that inhibiting PI3Kγ reduced the activity of pyruvate dehydrogenase (PDH), the key enzyme of Randle cycle, regulating the switch from fatty acids to glucose usage, while decreasing DOX-induced mobilization of GLUT-4-carrying vesicles to the plasma membrane, limiting subsequent glucose uptake. Conclusion These results demonstrate that DOX promotes an early metabolic rewiring with PI3Kγ-dependent increased glucose uptake and modulation of the Randle cycle towards augmented glucose utilization.

Mito-Specific Nutri-Hijacker Synergizing Mitochondrial Metabolism and Glycolysis Intervention for Enhanced Antitumor Bioenergetic Therapy.

Metabolic rewiring, a dynamic metabolic phenotype switch, confers that tumors exist and proliferate after fitness (or preadaptation) in harsh environmental conditions. Glycolysis deprivation was considered to be a tumor's metabolic Achilles heel. However, metabolic configuration can flexibly retune the mitochondrial metabolic ability when glycolysis is scared, potentially resulting in more aggressive clones. To address the challenge of mitochondrial reprogramming, an antiglycolytic nanoparticle (GRPP NP) containing a novel mitochondrial-targeted reactive oxygen species (ROS) generator (diIR780) was prepared to hijack glucose and regulate mitochondria, thus completely eliminating tumorigenic energy sources. In this process, GRPP NPs@diIR780 can catalyze endogenous glucose, leading to significantly suppressed glycolysis. Moreover, diIR780 can be released and selectively accumulated around mitochondria to generate toxic ROS. These combined effects, in turn, can hamper mitochondrial metabolism pathways, which are crucial for driving tumor progression. This synchronous intervention strategy enables utter devastation of metabolic rewiring, providing a promising regiment to eradicate tumor lesions without recurrence.

High-throughput proteomic analysis unveils metabolic and mitochondrial signaling rewiring by chronic ivabradine treatment in duchenne muscular dystrophy

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Austrian Science Fund (FWF) Objective Ivabradine (IVA) is indicated in symptomatic treatment of chronic stable angina, heart failure, and also in those who are unable to tolerate or have contraindications to the use of beta-blockers. It has been showed IVA may have cardiovascular benefits in Duchenne muscular dystrophy (DMD) patients. This study was aimed to investigate the sustained impact of chronic ivabradine (IVA) administration on cardiac function and potential underlying mechanism using high throutput proteomic analysis. Methods DMDmdx male and Sprague–Dawley wt (Sprague–Dawley) male rats were randomly allocated to vehicle (n = 6) or IVA (n=6; 10 mg/kg/day via drinking water for four months). Transthoracic echocardiography and unbiased proteomic analysis were performed to assess cardiac function and left ventricular (LV) tissue, respectively. Protein-protein interactions were graphically represented, and cluster analysis with subsequent enrichment analyses was conducted. Results Chronic IVA treatment significantly enhanced the LV ejection fraction (p<0.05 compared to vehicle-treated DMDmdx rats). Proteomic data identified possible transcription factors (SPI1, IRF1, PPARA), consistent with previous studies. The reduction in copper metabolic changes associated with DMD can be attributed to the upregulation of Atox1 following IVA treatment. Mitochondrial dysfunction was effectively mitigated by IVA, as indicated by the different abundance of mitochondrial proteins. In addition, intercellular adhesion molecule 1 showed a reduction in the number of animals treated with ivabradine, indicating a further positive effect of the treatment. Conclusion In summary, this study demonstrated the beneficial effects of IVA in DMDmdx rat hearts. Cluster analysis of proteomic data revealed notable changes in cardiac metabolism, inflammation, and mitochondrial function. Ivabradine has emerged as a potential therapeutic approach to address these shifts, while proteomic pathway analysis may uncover new drugable targets to alleviate cardiomyopathy progression in DMD.Interaction of IvabradinProtein-protein interaction network

MitoBKCa is functionally expressed in murine and human breast cancer cells and potentially contributes to metabolic reprogramming.

Alterations in the function of K+ channels such as the voltage- and Ca2+-activated K+ channel of large conductance (BKCa) reportedly promote breast cancer (BC) development and progression. Underlying molecular mechanisms remain, however, elusive. Here, we provide electrophysiological evidence for a BKCa splice variant localized to the inner mitochondrial membrane of murine and human BC cells (mitoBKCa). Through a combination of genetic knockdown and knockout along with a cell permeable BKCa channel blocker, we show that mitoBKCa modulates overall cellular and mitochondrial energy production, and mediates the metabolic rewiring referred to as the 'Warburg effect', thereby promoting BC cell proliferation in the presence and absence of oxygen. Additionally, we detect mitoBKCa and BKCa transcripts in low or high abundance, respectively, in clinical BC specimens. Together, our results emphasize, that targeting mitoBKCa could represent a treatment strategy for selected BC patients in future.

MitoBKCa is functionally expressed in murine and human breast cancer cells and potentially contributes to metabolic reprogramming

Alterations in the function of K+ channels such as the voltage- and Ca2+-activated K+ channel of large conductance (BKCa) reportedly promote breast cancer (BC) development and progression. Underlying molecular mechanisms remain, however, elusive. Here, we provide electrophysiological evidence for a BKCa splice variant localized to the inner mitochondrial membrane of murine and human BC cells (mitoBKCa). Through a combination of genetic knockdown and knockout along with a cell permeable BKCa channel blocker, we show that mitoBKCa modulates overall cellular and mitochondrial energy production, and mediates the metabolic rewiring referred to as the ‘Warburg effect’, thereby promoting BC cell proliferation in the presence and absence of oxygen. Additionally, we detect mitoBKCa and BKCa transcripts in low or high abundance, respectively, in clinical BC specimens. Together, our results emphasize, that targeting mitoBKCa could represent a treatment strategy for selected BC patients in future.

Intermittent hyperglycaemia induces macrophage dysfunction by extracellular regulated protein kinase-dependent PKM2 translocation in periodontitis.

Early fluctuations in blood glucose levels increased susceptibility to macrophage dysfunction. However, the underlying pathological mechanisms linking glucose variations and macrophage dysregulation remains elusive. In current study, we established an animal model of transient intermittent hyperglycaemia (TIH) to simulate early fluctuations in blood glucose levels. Our findings revealed that both TIH and diabetic group exhibited more severe periodontal lesions and increased secretion of pro-inflammatory cytokines compared to healthy controls. In immortalized bone marrow-derived macrophages (iBMDMs), phagocytosis and chemotaxis were impaired with transient and lasting hyperglycaemia, accompanied by enhanced glycolysis. We also found that TIH activated pyruvate kinase M2 (PKM2) through the phosphorylation of extracellular regulated protein kinase (ERK) in vivo, particularly at dimeric levels. In macrophage cultured with TIH, PKM2 translocated into the nucleus and involved in the regulating inflammatory genes, including TNF-α, IL-6 and IL-1β. PKM2 translocation and secretion of inflammatory cytokines were attenuated by PD98059, while PKM2 tetramer activator TEPP-46 prevented the formation of dimeric PKM2 in macrophages. Moreover, inhibition of glycolysis alleviated the TIH-induced pro-inflammatory cytokines. In conclusion, our manuscript provides a rationale for understanding how TIH modulates metabolic rewiring and dysfunction in macrophages via ERK-dependent PKM2 nuclear translocation.

#2048 Exploring somatic mutation mechanisms in pre-cystic renal cells of autosomal dominant polycystic kidney disease patients

Abstract Background and Aims Genetic changes accumulate in our cells during a lifetime, at a rate that varies according to cell type and mutagen exposure [1]. Somatic mutations are the driving force of cancer and contribute to “second hit” disorders, such as Autosomal Dominant Polycystic Kidney Disease (ADPKD). ADPKD is caused by inherited mutations that disrupt one allele of PKD1 or PKD2 genes. Somatic loss of the second allele triggers tubule cell clonal expansion and the formation of renal cysts. Given the high number of cysts that form during a lifetime, somatic mutation rates may be abnormally high in the kidney of ADPKD patients. The identification of factors enhancing somatic mutation rates can lead to preventive strategies to limit cyst formation. Metabolic alterations, i.e. increased glutamine utilization and reduced urea cycle, have been shown to induce somatic mutations in cancer [2]. Loss of urea cycle increases pyrimidine synthesis, which unbalances the nucleotide pools and results in a distinct signature of single base substitutions (SBSs) [1]. Similar metabolic changes have been observed in ADPKD [3, 4]. Thus, we sought to test metabolism-driven somatic mutagenesis in pre-cystic kidneys and its contribution to second hit mutations in ADPKD. Method We clonally expanded normal kidney cells from human urine samples and performed a gene expression study by qPCR. We studied 31 clones from 4 ADPKD patients (age range: 25-45) with truncating mutations in PKD1 and normal kidney function, despite a clear cystic phenotype. ADPKD cells were compared to 55 clones from 5 healthy volunteers (age range: 24-53), and 32 clones from 6 patients with another cystic kidney disease, Von Hippel Lindau disease (VHL; age range: 29-56). A subset of clones (n = 19 controls, n = 12 ADPKD) was subjected to whole genome sequencing and somatic mutation analysis. Results Urines of ADPKD patients contained higher numbers of cells that expanded in vitro, compared to both control (p = 0.0008) and VHL individuals (p = 0.01). Gene expression analyses showed that irrespective of genetic background, all cultured clones originated from the kidney tubule epithelium (high PAX2 and PAX8), and some originated from damaged tubules (VCAM1, KIM1). We tested the hypothesized metabolic rewiring by analyzing expression levels of enzymes involved in glutamine utilization, urea cycle, and pyrimidine biosynthesis. Except for ASNS (Asparagine Synthetase), which was higher in ADPKD vs control clones (p = 0.0098), no gene-expression differences were observed. However, clones from ADPKD patients showed signs of the metabolic rewiring responsible for increased pyrimidine production, i.e. a positive correlation (r = 0.691; p < 0.0001) between urea cycle enzymes downregulation and upregulation of the pyrimidine synthesis enzyme CAD. Since excessive pyrimidines lead to mutation [2], we analyzed the number of somatic SBSs per genome, after filtering for germline variants. We did not find increased mutation rates in ADPKD compared to controls, but an analogous, linear increase of mutations with age and similar levels of the pyrimidine-rich mutational signature. Conclusion Urine-derived kidney tubule epithelial cells with heterozygous truncating mutations in PKD1 exhibit certain characteristics of metabolic reprogramming typical of kidneys from ADPKD patients with advanced pathology. Nevertheless, in the limited number of pre-cystic cells that we have analyzed, this metabolic reprogramming did not translate into an excess of somatic mutations.

Ovarian Cancer Cell-Conditioning Medium Induces Cancer-Associated Fibroblast Phenoconversion through Glucose-Dependent Inhibition of Autophagy.

One aspect of ovarian tumorigenesis which is still poorly understood is the tumor-stroma interaction, which plays a major role in chemoresistance and tumor progression. Cancer-associated fibroblasts (CAFs), the most abundant stromal cell type in the tumor microenvironment, influence tumor growth, metabolism, metastasis, and response to therapy, making them attractive targets for anti-cancer treatment. Unraveling the mechanisms involved in CAFs activation and maintenance is therefore crucial for the improvement of therapy efficacy. Here, we report that CAFs phenoconversion relies on the glucose-dependent inhibition of autophagy. We show that ovarian cancer cell-conditioning medium induces a metabolic reprogramming towards the CAF-phenotype that requires the autophagy-dependent glycolytic shift. In fact, 2-deoxy-D-glucose (2DG) strongly hampers such phenoconversion and, most importantly, induces the phenoreversion of CAFs into quiescent fibroblasts. Moreover, pharmacological inhibition (by proline) or autophagy gene knockdown (by siBECN1 or siATG7) promotes, while autophagy induction (by either 2DG or rapamycin) counteracts, the metabolic rewiring induced by the ovarian cancer cell secretome. Notably, the nutraceutical resveratrol (RV), known to inhibit glucose metabolism and to induce autophagy, promotes the phenoreversion of CAFs into normal fibroblasts even in the presence of ovarian cancer cell-conditioning medium. Overall, our data support the view of testing autophagy inducers for targeting the tumor-promoting stroma as an adjuvant strategy to improve therapy success rates, especially for tumors with a highly desmoplastic stroma, like ovarian cancer.

An evolutionarily conserved mechanism controls reversible amyloids of pyruvate kinase via pH-sensing regions

Amyloids are known as irreversible aggregates associated with neurodegenerative diseases. However, recent evidence shows that a subset of amyloids can form reversibly and fulfill essential cellular functions. Yet, the molecular mechanisms regulating functional amyloids and distinguishing them from pathological aggregates remain unclear. Here, we investigate the conserved principles of amyloid reversibility by studying the essential metabolic enzyme pyruvate kinase (PK) in yeast and human cells. We demonstrate that yeast PK (Cdc19) and human PK (PKM2) form reversible amyloids through a pH-sensitive amyloid core. Stress-induced cytosolic acidification promotes aggregation via protonation of specific glutamate (yeast) or histidine (human) residues within the amyloid core. Mutations mimicking protonation cause constitutive PK aggregation, while non-protonatable PK mutants remain soluble even upon stress. Physiological PK aggregation is coupled to metabolic rewiring and glycolysis arrest, causing severe growth defects when misregulated. Our work thus identifies an evolutionarily conserved, potentially widespread mechanism regulating functional amyloids during stress.

Combinatorial microRNA activity is essential for the transition of pluripotent cells from proliferation into dormancy.

Dormancy is a key feature of stem cell function in adult tissues as well as in embryonic cells in the context of diapause. The establishment of dormancy is an active process that involves extensive transcriptional, epigenetic, and metabolic rewiring. How these processes are coordinated to successfully transition cells to the resting dormant state remains unclear. Here we show that microRNA activity, which is otherwise dispensable for preimplantation development, is essential for the adaptation of early mouse embryos to the dormant state of diapause. In particular, the pluripotent epiblast depends on miRNA activity, the absence of which results in the loss of pluripotent cells. Through the integration of high-sensitivity small RNA expression profiling of individual embryos and protein expression of miRNA targets with public data of protein-protein interactions, we constructed the miRNA-mediated regulatory network of mouse early embryos specific to diapause. We find that individual miRNAs contribute to the combinatorial regulation by the network, and the perturbation of the network compromises embryo survival in diapause. We further identified the nutrient-sensitive transcription factor TFE3 as an upstream regulator of diapause-specific miRNAs, linking cytoplasmic MTOR activity to nuclear miRNA biogenesis. Our results place miRNAs as a critical regulatory layer for the molecular rewiring of early embryos to establish dormancy.

Targeting the glutamine metabolism to suppress cell proliferation in mesenchymal docetaxel-resistant prostate cancer

Docetaxel (DX) serves as a palliative treatment option for metastatic prostate cancer (PCa). Despite initial remission, acquired DX resistance is inevitable. The mechanisms behind DX resistance have not yet been deciphered, but a mesenchymal phenotype is associated with DX resistance. Mesenchymal phenotypes have been linked to metabolic rewiring, obtaining most ATP production by oxidative phosphorylation (OXPHOS) powered substantially by glutamine (Gln). Likewise, Gln is known to play an essential role in modulating bioenergetic, redox homeostasis and autophagy. Herein, investigations of Gln deprivation on DX-sensitive and -resistant (DR) PCa cells revealed that the DR cell sub-lines were susceptible to Gln deprivation. Mechanistically, Gln deprivation reduced OXPHOS and ATP levels, causing a disturbance in cell cycle progression. Genetic and chemical inhibition of the Gln-metabolism key protein GLS1 could validate the Gln deprivation results, thereby representing a valid therapeutic target. Moreover, immunohistological investigation of GLS1 revealed a high-expressing GLS1 subgroup post-docetaxel failure, exhibiting low overall survival. This subgroup presents an intriguing opportunity for targeted therapy focusing on glutamine metabolism. Thus, these findings highlight a possible clinical rationale for the chemical inhibition of GLS1 as a therapeutic strategy to target mesenchymal DR PCa cells, thereby delaying accelerated tumour progression.

Skeletal muscle hypertrophy rewires glucose metabolism: An experimental investigation and systematic review.

Proliferating cancer cells shift their metabolism towards glycolysis, even in the presence of oxygen, to especially generate glycolytic intermediates as substrates for anabolic reactions. We hypothesize that a similar metabolic remodelling occurs during skeletal muscle hypertrophy. We used mass spectrometry in hypertrophying C2C12 myotubes in vitro and plantaris mouse muscle in vivo and assessed metabolomic changes and the incorporation of the [U-13C6]glucose tracer. We performed enzyme inhibition of the key serine synthesis pathway enzyme phosphoglycerate dehydrogenase (Phgdh) for further mechanistic analysis and conducted a systematic review to align any changes in metabolomics during muscle growth with published findings. Finally, the UK Biobank was used to link the findings to population level. The metabolomics analysis in myotubes revealed insulin-like growth factor-1 (IGF-1)-induced altered metabolite concentrations in anabolic pathways such as pentose phosphate (ribose-5-phosphate/ribulose-5-phosphate: +40%; P=0.01) and serine synthesis pathway (serine: -36.8%; P=0.009). Like the hypertrophy stimulation with IGF-1 in myotubes in vitro, the concentration of the dipeptide l-carnosine was decreased by 26.6% (P=0.001) during skeletal muscle growth in vivo. However, phosphorylated sugar (glucose-6-phosphate, fructose-6-phosphate or glucose-1-phosphate) decreased by 32.2% (P=0.004) in the overloaded muscle in vivo while increasing in the IGF-1-stimulated myotubes in vitro. The systematic review revealed that 10 metabolites linked to muscle hypertrophy were directly associated with glycolysis and its interconnected anabolic pathways. We demonstrated that labelled carbon from [U-13C6]glucose is increasingly incorporated by ~13% (P=0.001) into the non-essential amino acids in hypertrophying myotubes, which is accompanied by an increased depletion of media serine (P=0.006). The inhibition of Phgdh suppressed muscle protein synthesis in growing myotubes by 58.1% (P<0.001), highlighting the importance of the serine synthesis pathway for maintaining muscle size. Utilizing data from the UK Biobank (n=450243), we then discerned genetic variations linked to the serine synthesis pathway (PHGDH and PSPH) and to its downstream enzyme (SHMT1), revealing their association with appendicular lean mass in humans (P<5.0e-8). Understanding the mechanisms that regulate skeletal muscle mass will help in developing effective treatments for muscle weakness. Our results provide evidence for the metabolic rewiring of glycolytic intermediates into anabolic pathways during muscle growth, such as in serine synthesis.

Integration of proteomic and metabolomic analysis reveal distinct metabolic alterations of prostate cancer-associated fibroblasts compared to normal fibroblasts from patient's stroma samples

The prostate gland is a complex and heterogeneous organ composed of epithelium and stroma. Whilst many studies into prostate cancer focus on epithelium, the stroma is known to play a key role in disease with the emergence of a cancer-associated fibroblasts (CAF) phenotype associated upon disease progression. In this work, we studied the metabolic rewiring of stromal fibroblasts following differentiation to a cancer-associated, myofibroblast-like, phenotype. We determined that CAFs were metabolically more active compared to normal fibroblasts. This corresponded with a heightened lipogenic metabolism, as both reservoir species and building block compounds. Interestingly, lipid metabolism affects mitochondria functioning yet the mechanisms of lipid-mediated functions are unclear. Data showing oxidised fatty acids and glutathione system are elevated in CAFs, compared to normal fibroblasts, strengthens the hypothesis that increased metabolic activity is related to mitochondrial activity. This manuscript describes mechanisms responsible for the altered metabolic flux and shows that prostate cancer-derived extracellular vesicles can increase basal respiration in normal fibroblasts, mirroring that of the disease-like phenotype. This indicates that extracellular vesicles derived from prostate cancer cells may drive an altered oxygen-dependent metabolism associated to mitochondria in CAFs.

High fat diet ameliorates mitochondrial cardiomyopathy in CHCHD10 mutant mice

Mutations in CHCHD10, a mitochondrial protein with undefined functions, are associated with autosomal dominant mitochondrial diseases. Chchd10 knock-in mice harboring a heterozygous S55L mutation (equivalent to human pathogenic S59L) develop a fatal mitochondrial cardiomyopathy caused by CHCHD10 aggregation and proteotoxic mitochondrial integrated stress response (mtISR). In mutant hearts, mtISR is accompanied by a metabolic rewiring characterized by increased reliance on glycolysis rather than fatty acid oxidation. To counteract this metabolic rewiring, heterozygous S55L mice were subjected to chronic high-fat diet (HFD) to decrease insulin sensitivity and glucose uptake and enhance fatty acid utilization in the heart. HFD ameliorated the ventricular dysfunction of mutant hearts and significantly extended the survival of mutant female mice affected by severe pregnancy-induced cardiomyopathy. Gene expression profiles confirmed that HFD increased fatty acid utilization and ameliorated cardiomyopathy markers. Importantly, HFD also decreased accumulation of aggregated CHCHD10 in the S55L heart, suggesting activation of quality control mechanisms. Overall, our findings indicate that metabolic therapy can be effective in mitochondrial cardiomyopathies associated with proteotoxic stress.

3D-bioprinted anti-senescence organoid scaffolds repair cartilage defect and prevent joint degeneration via miR-23b/ELOVL5-mediated metabolic rewiring

IntroductionOsteoarthritis (OA) is the most prevalent degenerative disease worldwide and commonly occurs among the elderly. At present, there is no effective treatment for OA. When OA develops to the end stage, arthroplasty is generally operated to improve the life quality of patients. Targeting senescence has been considered as a therapeutic approach for OA in recent years. Methods & resultsIn this study, we have identified P16 gene as a novel target for anti-senescence strategy and harnessed small interfering RNA (siRNA) technology to fabricate P16-siRNA encapsulated PLGA microspheres. We combined this with our previously successful three-dimensional (3D) culture of functionally bioengineered chondrogenic synovial mesenchymal stromal cell (SMSC) organoids. This served as the primary component of the bio-ink for 3D bioprinting, culminating in the creation of P16-siRNA PLGA µS and SMSC organoid hydrogel-polymer composite scaffold (PPSOH). Its superior capabilities of cartilage repair were confirmed through in vivo and in vitro experimentations. In the rabbit model of knee cartilage defects, PPSOH not only restored the superior characteristics of native healthy hyaline cartilage but also maintained post-implanted joint function. It prevented development of joint degeneration resulting from cartilage defects by mitigating intra-articular inflammatory responses and cellular senescence. Our usage of miRNA and RNA sequencing reveals that PPSOH targets the miR-23b/ELOVL5 axis and rewired cellular metabolism, therefore regulating glycolysis and fatty acid oxidation. This effectively alleviates cellular senescence, promotes relief from OA, and facilitates cartilage regeneration. ConclusionPPSOH scaffold could effectively alleviate cellular senescence, foster relief from OA, and facilitate cartilage regeneration. Further experiments disclosed that PPSOH targets the miR-23b/ELOVL5 axis and rewired cellular metabolism by regulating glycolysis and fatty acid oxidation. Therefore, PPSOH could be used as potential therapy for cartilage repair in osteoarthritic patients.

Reprogrammed mitochondria: a central hub of cancer cell metabolism.

Mitochondria represent the metabolic hub of normal cells and play this role also in cancer but with different functional purposes. While cells in differentiated tissues have the prerogative of maintaining basal metabolism and support the biosynthesis of specialized products, cancer cells have to rewire the metabolic constraints imposed by the differentiation process. They need to balance the bioenergetic supply with the anabolic requirements that entail the intense proliferation rate, including nucleotide and membrane lipid biosynthesis. For this aim, mitochondrial metabolism is reprogrammed following the activation of specific oncogenic pathways or due to specific mutations of mitochondrial proteins. The main process leading to mitochondrial metabolic rewiring is the alteration of the tricarboxylic acid cycle favoring the appropriate orchestration of anaplerotic and cataplerotic reactions. According to the tumor type or the microenvironmental conditions, mitochondria may decouple glucose catabolism from mitochondrial oxidation in favor of glutaminolysis or disable oxidative phosphorylation for avoiding harmful production of free radicals. These and other metabolic settings can be also determined by the neo-production of oncometabolites that are not specific for the tissue of origin or the accumulation of metabolic intermediates able to boost pro-proliferative metabolism also impacting epigenetic/transcriptional programs. The full characterization of tumor-specific mitochondrial signatures may provide the identification of new biomarkers and therapeutic opportunities based on metabolic approaches.

A global view of T cell metabolism in systemic lupus erythematosus.

Impaired metabolism is recognized as an important contributor to pathogenicity of T cells in Systemic Lupus Erythematosus (SLE). Over the last two decades, we have acquired significant knowledge about the signaling and transcriptomic programs related to metabolic rewiring in healthy and SLE T cells. However, our understanding of metabolic network activity derives largely from studying metabolic pathways in isolation. Here, we argue that enzymatic activities are necessarily coupled through mass and energy balance constraints with in-built network-wide dependencies and compensation mechanisms. Therefore, metabolic rewiring of T cells in SLE must be understood in the context of the entire network, including changes in metabolic demands such as shifts in biomass composition and cytokine secretion rates as well as changes in uptake/excretion rates of multiple nutrients and waste products. As a way forward, we suggest cell physiology experiments and integration of orthogonal metabolic measurements through computational modeling towards a comprehensive understanding of T cell metabolism in lupus.

Abstract PO3-25-08: Artificial Intelligence-based screening of small molecule inhibitors of phosphoenolpyruvate carboxykinase 2 (PCK2), a novel cancer therapeutic target

Abstract Background: Metabolic rewiring is a hallmark of cancer that is often mediated by alterations in metabolic isozyme expression. Isozymes that are overexpressed in cancer and catalyze rate limiting steps in key metabolic processes are potential therapeutic targets. We previously identified phosphoenolpyruvate carboxykinase 2 (PCK2) as cancer dominant isoform, required for maintaining high metabolic activity and proliferation of lung, prostate, and breast cancer (BC) cells in vitro and in vivo. No PCK2 specific small molecule inhibitors exist. Methods: mRNA expression levels were assessed in the TCGA data. PCK2 MISSION shRNAs (Millipore) were used to knock-down expression of PCK2 in BC cells. Alterations in metabolic flux caused by PCK2 down-regulation were examined via 13C-labeling and mass spectrometry using a SCIEX 5500 QTRAP and SelexION instrument for mobility separation of metabolites. The AtomNetTM (Atomwise Inc.) deep convolutional neural network structure-based drug design software was used to identify candidate small molecule PCK2 inhibitors which were tested in PCK1 and PCK2 in vitro enzyme activity assays. The lead compound was assessed for drug-like properties by QickPropV4.0.001w, and its growth inhibitory activity was tested in MDA-MB-321 and BT-549 cells. Results: Analysis of mRNA levels in TNBC samples revealed a significant decrease in PCK1 expression compared to normal tissues, while PCK2 expression remained elevated or even increased. Quantification of mRNA levels in TNBC cell lines confirmed the higher expression of PCK2 compared to PCK1. To assess functional significance of PCK2 expression, we downregulated PCK2 using shRNA constructs in TNBC cell lines. Western blot analysis confirmed efficient knockdown of PCK2 protein without affecting PCK1 expression. Clonogenic assays demonstrated that PCK2-depleted BT-549 and MDA-MB-231 cells exhibited impaired proliferation, with reduced colony number and size compared to control cells. Metabolic analysis of PCK2-depleted TNBC cells demonstrated decreased levels of glycolytic and TCA intermediates and reduced flux through pyruvate carboxylase, indicating altered metabolic pathways upon PCK2 depletion. To identify potential inhibitors of PCK2, virtual screening was conducted using compound structures. We used a PCK2 protein structure homology model and designated the 3-mercaptopicolinic acid-binding site of the PCK1 structure as the site of interest to perform virtual drug screening of 7 million diverse compounds. The first screen yielded 86 structures to be tested in vitro, of which 5 demonstrated &amp;gt; 16% PCK2 inhibition. The top hit (IC50=2.4µM) was used to refine a second round of in silico screen that yielded 87 second-round candidates that were assessed for PCK2 inhibition in vitro. 3-(3,4-dihydroxyphenyl)-2-hydroxypropanoate emerged as the lead compound. QickProp predicted favorable absorption, distribution, metabolism, and excretion properties, but relatively low cell permeability (apparent Caco-2 and MDCK2 cell permeabilities 18 nm/sec and 8 nm/sec, respectively). The specificity of 3-(3,4-dihydroxyphenyl)-2-hydroxypropanoate was tested in PCK1 and PCK2 enzymatic assays and revealed IC50 of 500nM on PCK1 and an IC50 of 3 nM on PCK2. We next tested the cell growth inhibitory effect of 3-(3,4-dihydroxyphenyl)-2-hydroxypropanoate on parental MDA-MB-231 and BT-549 cells and their PCK2 knockdown clones. Cell growth and viability significantly decreased in the MDA-MD-231 and BT-549 parental cells (the IC50 for MDA-MB-231 was 173 μM) and in shRNA non-targeting control cells, but not in the PCK2 depleted clones, demonstrating PCK2-dependent inhibitory effect. Conclusion: We identified 3-(3,4-dihydroxyphenyl)-2-hydroxypropanoate as a high affinity selective PCK2 enzyme inhibitor. This compound also has significant growth inhibitory activity in BC cell lines in vitro and represents a novel therapeutic lead compound. Citation Format: Alejandro Rios Hoyo, Naing Lin Shan, Hao-Kuen Lin, Gerson Espinoza Campos, Mostafa Ahmed, Sheila Umlauf, Rebecca Cardone, Yulia V. Surovtseva, Vignesh Gunasekharan, Lajos pusztai. Artificial Intelligence-based screening of small molecule inhibitors of phosphoenolpyruvate carboxykinase 2 (PCK2), a novel cancer therapeutic target [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-25-08.