ATP Production Research Articles

Helicobacter pylori VacA-induced mitochondrial damage in the gastric pit cells of the antrum and therapeutic rescue

Exploring host cell specificity, pathogenicity, and molecular mechanisms of the vacuolating cytotoxin A (VacA), secreted by Helicobacter pylori (Hp) is crucial for developing novel treatment strategies. VacA affects subcellular events, particularly mitochondria, at a cell-type-specific level. However, the lack of reliable models that mimic VacA-induced subcellular damages and enable novel drug screening linked to the human stomach clinically limits our understanding of the mitochondrial networks in vivo. Here, human antrum gastric organoids (hAGOs) and tissue samples from Hp-infected patients were used to show the toxic effects of VacA-induced mitochondrial damage mainly in mucus-producing gastric pit cells by employing transcriptional, translational, and functional analyses. In VacA-intoxicated or Hp-infected hAGOs, robust mitochondrial fragmentation in gastric pit cells reduced ATP production during respiration, and loss of mucosal barrier integrity was first demonstrated experimentally. Using hAGOs, clinically relevant small molecules were screened for efficacy, and MLN8054, an Aurora kinase A inhibitor, reversed VacA-induced mitochondrial damage and loss of gastric epithelium integrity. MLN8054 was effective in VacA-treated and Hp-infected hAGOs and mice, highlighting hAGOs as a promising drug-screening model. These findings suggest that mitochondrial quality control may serve as a promising therapeutic target for Hp VacA-mediated toxicity and disease progression.

Mitochondria facilitate neuronal differentiation by metabolising nuclear-encoded RNA

Mitochondrial activity directs neuronal differentiation dynamics during brain development. In this context, the long-established metabolic coupling of mitochondria and the eukaryotic host falls short of a satisfactory mechanistic explanation, hinting at an undisclosed facet of mitochondrial function. Here, we reveal an RNA-based inter-organellar communication mode that complements metabolic coupling of host-mitochondria and underpins neuronal differentiation. We show that within minutes of exposure to differentiation cues and activation of the electron transport chain, the mitochondrial outer membrane transiently fuses with the nuclear membrane of neural progenitors, leading to efflux of nuclear-encoded RNAs (neRNA) into the positively charged mitochondrial intermembrane space. Subsequent degradation of mitochondrial neRNAs by Polynucleotide phosphorylase 1 (PNPase) located in the intermembrane space curbs the transcriptomic memory of progenitor cells. Further, acquisition of neRNA by mitochondria leads to a collapse of proton motive force, suppression of ATP production, and a resultant amplification of autophagic flux that attenuates proteomic memory. Collectively, these events force the progenitor cells towards a “tipping point” characterised by emergence of a competing neuronal differentiation program. It appears that neuronal differentiation is a consequence of reprogrammed coupling of metabolomic and transcriptomic landscapes of progenitor cells, with mitochondria emerging as key “reprogrammers” that operate by acquiring and metabolising neRNAs. However, the documented role of mitochondria as “reprogrammers” of differentiation remains to be validated in other neuronal lineages and in vivo.

A tomato a day keeps the beetle away - the impact of Solanaceae glycoalkaloids on energy management in the mealworm Tenebrio molitor.

Solanine (SOL), chaconine (CHA), and tomatine (TOM) are plant secondary metabolites produced mainly by the species of Solanaceae family, such as tomato Solanum lycopersicum L. These glycoalkaloids (GAs) have a wide range of biological activity, also in insects. However, their mechanisms of action are not precisely understood. The purpose of the study was to investigate how pure GAs and tomato leaf extract (EXT) affect glycolysis, Krebs cycle and β-oxidation of fatty acid pathways in Tenebrio molitor L. beetle. For this purpose, the larvae were injected with SOL, CHA, TOM, and EXT at two concentrations (10-8 and 10-5M). For experiments, fat body, gut, and heamolymph samples were collected 2 and 24h after injection. Then, the changes in the expression level of phosphofructokinase, citrate synthase, and β-hydroxyacyl-CoA dehydrogenase were measured using the RT-qPCR technique. The catalytic activity of these enzymes and the carbohydrate level in insects after GA treatment were determined by spectrophotometric method. Furthermore, the analysis of the amount of amino acids in tissues was performed with a GC-MS technique. The results obtained show that the GAs changed the activity and expression of the genes encoding key enzymes of crucial metabolic pathways. The effect depends on the type of GA compound, the tissue tested, and the incubation time after treatment. Furthermore, TOM and EXT affected trehalose concentration in the insect hemolymph and led to accumulation of amino acids in the fat body. The observed changes may indicate a protein degradation and/or enhanced catabolism reactions for the production of ATP used in detoxification processes. These results suggest that GAs alter energy metabolism in the mealworm T. molitor. The study contributes to our understanding of the mechanisms of action of secondary metabolites of plants in insects. This knowledge may allow the design of new natural biopesticides against insect pests because proper energy metabolism is necessary for the survival of the organism.

Synthesis and Biological Evaluation ofN-(1H-Indol-6-ylmethyl)benzenesulfonamide Analogs as Metabolic Inhibitors of Mitochondrial ATP Production in Pancreatic Cancer Cells.

A library of 26 indolyl sulfonamides and 12 amide and ester analogs based upon the 6-indolyl framework has been synthesized in an effort to target pancreatic cancer. The cytotoxicity of the indolyl sulfonamide compounds has been determined using a traditional (48-hour compound exposure) assay against 7 pancreatic cancer cell lines and 1 non-cancerous cell line. The potential role of the compounds as metabolic inhibitors of ATP production was evaluated using a rapid screening (2-hour compound exposure) assay developed within our laboratories. The IC50 values of the active compounds were determined using the rapid assay and six compounds displayed an IC50 value <5 μM against one or more pancreatic cancer cell lines. The ester analogs also display significant activity as potential metabolic inhibitors of ATP production with four of the six compounds displaying an IC50 value <5 μM against one or more pancreatic cancer cell lines.

Exploring the role of mitochondrial uncoupling protein 4 in brain metabolism: implications for Alzheimer's disease.

The brain's high demand for energy necessitates tightly regulated metabolic pathways to sustain physiological activity. Glucose, the primary energy substrate, undergoes complex metabolic transformations, with mitochondria playing a central role in ATP production via oxidative phosphorylation. Dysregulation of this metabolic interplay is implicated in Alzheimer's disease (AD), where compromised glucose metabolism, oxidative stress, and mitochondrial dysfunction contribute to disease progression. This review explores the intricate bioenergetic crosstalk between astrocytes and neurons, highlighting the function of mitochondrial uncoupling proteins (UCPs), particularly UCP4, as important regulators of brain metabolism and neuronal function. Predominantly expressed in the brain, UCP4 reduces the membrane potential in the inner mitochondrial membrane, thereby potentially decreasing the generation of reactive oxygen species. Furthermore, UCP4 mitigates mitochondrial calcium overload and sustains cellular ATP levels through a metabolic shift from mitochondrial respiration to glycolysis. Interestingly, the levels of the neuronal UCPs, UCP2, 4 and 5 are significantly reduced in AD brain tissue and a specific UCP4 variant has been associated to an increased risk of developing AD. Few studies modulating the expression of UCP4 in astrocytes or neurons have highlighted protective effects against neurodegeneration and aging, suggesting that pharmacological strategies aimed at activating UCPs, such as protonophoric uncouplers, hold promise for therapeutic interventions in AD and other neurodegenerative diseases. Despite significant advances, our understanding of UCPs in brain metabolism remains in its early stages, emphasizing the need for further research to unravel their biological functions in the brain and their therapeutic potential.

Facilitating Intracellular Electron Bifurcation by Mediating Flavin-Based Extracellular and Transmembrane Electron Transfer: A Novel Role of Pyrogenic Carbon in Dark Fermentation for Hydrogen Production.

Pyrogenic carbon is considered an enhancer to H2-yielding dark fermentation (DF), but little is known about how it regulates extracellular electron transfer (EET) and influences transmembrane respiratory chains and intracellular metabolisms. This study addressed these knowledge gaps and demonstrated that wood waste pyrogenic carbon (biochar) could significantly improve the DF performance; e.g., addition of pyrogenic carbon produced by pyrolysis at 800 °C (PC800) increased H2 yield by 369.7%. Biochemical quantification, electrochemical analysis, and electron respiratory chain inhibition tests revealed that PC800 promoted the extracellular flavin-based electron transfer process and further activated the acceleration of the transmembrane electron transfer. Comparative metagenome/metatranscriptome analyses indicated that the flavin-containing Rnf complex was the potential transmembrane respiratory enzyme associated with PC800-mediated EET. Based on NADH/NAD+ circulation, the promoted Rnf complex could stimulate the functions of the electron bifurcating Etf/Bcd complex and startup of glycolysis. The promoted Etf/Bcd could further contribute to balance the NADH/NAD+ level for glycolytic reactions and meanwhile provide reduced ferredoxin for group A1 [FeFe]-hydrogenases. This proton-energy-linked mechanism could achieve coupling production of ATP and H2. This study verified the important roles of pyrogenic carbon in mediating EET and transmembrane/intracellular pathways and revealed the crucial roles of electron bifurcation in DF for hydrogen production.

New Application of an Old Drug: Anti-Diabetic Properties of Phloroglucinol.

Phloroglucinol (PHG), an analgesic and spasmolytic drug, shows promise in preventing high-fat-diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) and insulin resistance. In Wistar rats, 10 weeks of PHG treatment did not prevent HFD-induced weight gain but significantly mitigated fasting hyperglycemia, impaired insulin responses, and liver steatosis. This protective effect was not linked to hepatic lipogenesis or AMP-activated protein kinase (AMPK) activation. Instead, PHG improved mitochondrial function by reducing oxidative stress, enhancing ATP production, and increasing anti-oxidant enzyme activity. PHG also relaxed gastric smooth muscles via potassium channel activation and nitric oxide (NO) signaling, potentially delaying gastric emptying. A pilot intervention in pre-diabetic men confirmed PHG's efficacy in improving postprandial glycemic control and altering lipid metabolism. These findings suggest PHG as a potential therapeutic for NAFLD and insulin resistance, acting through mechanisms involving mitochondrial protection, anti-oxidant activity, and gastric motility modulation. Further clinical evaluation is warranted to explore PHG's full therapeutic potential.

Mitochondrial genome-derived circRNAs: Orphan epigenetic regulators in molecular biology

Mitochondria are vital for cellular activities, influencing ATP production, Ca2+ signaling, and reactive oxygen species generation. It has been proposed that nuclear genome-derived circular RNAs (circRNAs) play a role in biological processes. For the first time, this study aims to comprehensively explore experimentally confirmed human mitochondrial genome-derived circRNAs (mt-circRNAs) via in-silico analysis. We utilized wide-ranging bioinformatics tools to anticipate their roles in molecular biology, involving miRNA sponging, protein antagonism, and peptide translation. Among five well-characterized mt-circRNAs, SCAR/mc-COX2 stands out as particularly significant with the potential to sponge around 41 different miRNAs, which target several genes mostly involved in endocytosis, MAP kinase, and PI3K-Akt pathways. Interestingly, circMNTND5 and mecciND1 specifically interact with miRNAs through their unique back-splice junction sequence. These exclusively targeted miRNAs (has-miR-5186, 6888-5p, 8081, 924, 672-5p) are predominantly associated with insulin secretion, proteoglycans in cancer, and MAPK signaling pathways. Moreover, all mt-circRNAs intricately affect the P53 pathway through miRNA sequestration. Remarkably, mc-COX2 and circMNTND5 appear to be involved in the RNA’s biogenesis by antagonizing AGO1/2, EIF4A3, and DGCR8. All mt-circRNAs engaged with IGF2BP proteins crucial in redox signaling, and except mecciND1, they all potentially generate at least one protein resembling the immunoglobulin heavy chain protein. Given P53′s function as a redox-sensitive transcription factor, and insulin’s role as a crucial regulator of energy metabolism, their indirect interplay with mt-circRNAs could influence cellular outcomes. However, due to limited attention and infrequent data availability, it is advisable to conduct more thorough investigations to gain a deeper understanding of the functions of mt-circRNA.

Exendin-4 exhibits cardioprotective effects against high glucose-induced mitochondrial abnormalities: Potential role of GLP-1 receptor and mTOR signaling

Mitochondrial dysfunction is associated with hyperglycemic conditions and insulin resistance leading to cellular damage and apoptosis of cardiomyocytes in diabetic cardiomyopathy. The dysregulation of glucagon-like peptide-1 (GLP-1) receptor and mammalian target of rapamycin (mTOR) is linked to cardiomyopathies and myocardial dysfunctions mediated by hyperglycemia. However, the involvements of mTOR for GLP-1 receptor-mediated cardioprotection against high glucose (HG)-induced mitochondrial disturbances are not clearly identified. The present study demonstrated that HG-induced cellular stress and mitochondrial damage resulted in impaired ATP production and oxidative defense markers such as catalase and SOD2, along with a reduction in survival markers such as Bcl-2 and p-Akt, while an increased expression of pro-apoptotic marker Bax was observed in H9c2 cardiomyoblasts. In addition, the autophagic marker LC3-II was considerably reduced, together with the disruption of autophagy regulators (p-mTOR and p-AMPKα) under the hyperglycemic state. Furthermore, there was a dysregulated expression of several indicators related to mitochondrial homeostasis, including MFN2, p-DRP1, FIS1, MCU, UCP3, and Parkin. Remarkably, treatment with either exendin-4 (GLP-1 receptor agonist) or rapamycin (mTOR inhibitor) significantly inhibited HG-induced mitochondrial damage while co-treatment of exendin-4 and rapamycin completely reversed all mitochondrial abnormalities. Antagonism of GLP-1 receptors using exendin-(9–39) abolished these cardioprotective effects of exendin-4 and rapamycin under HG conditions. In addition, exendin-4 attenuated HG-induced phosphorylation of mTOR, and this inhibitory effect was antagonized by exendin-(9–39), indicating the regulation of mTOR by GLP-1 receptor. Therefore, improvement of mitochondrial dysfunction by stimulating the GLP-1 receptor/AMPK/Akt pathway and inhibiting mTOR signaling could ameliorate cardiac abnormalities caused by hyperglycemic conditions.

ZFP64 drives glycolysis-mediated stem cell-like properties and tumorigenesis in breast cancer

BackgroundBreast cancer (BC) is a great clinical challenge because of its aggressiveness and poor prognosis. Zinc Finger Protein 64 (ZFP64), as a transcriptional factor, is responsible for the development and progression of cancers. This study aims to investigate whether ZFP64 regulates stem cell-like properties and tumorigenesis in BC by the glycolytic pathway.ResultsIt was demonstrated that ZFP64 was overexpressed in BC specimens compared to adjacent normal tissues, and patients with high ZFP64 expression had shorter overall survival and disease-free survival. The analysis of the association of ZFP64 expression with clinicopathological characteristics showed that high ZFP64 expression is closely associated with N stage, TNM stage, and progesterone receptor status. Knockdown of ZFP64 suppressed the viability and colony formation capacity of BC cells by CCK8 and colony formation assays. The subcutaneous xenograft models revealed that ZFP64 knockdown reduced the volume of formatted tumors, and decreased Ki67 expression in tumors. The opposite effects on cell proliferation and tumorigenesis were demonstrated by ZFP64 overexpression. Furthermore, we suggested that the stem cell-like properties of BC cells were inhibited by ZFP64 depletion, as evidenced by the decreased size and number of formatted mammospheres, the downregulated expressions of OCT4, Nanog, and SOX2 proteins, as well as the reduced proportion of CD44+/CD24− subpopulations. Mechanistically, glycolysis was revealed to mediate the effect of ZFP64 using mRNA-seq analysis. Results showed that ZFP64 knockdown blocked the glycolytic process, as indicated by decreasing glycolytic metabolites, inhibiting glucose consumption, and reducing lactate and ATP production. As a transcription factor, we identified that ZFP64 was directly bound to the promoters of glycolysis-related genes (ALDOC, ENO2, HK2, and SPAG4), and induced the transcription of these genes by ChIP and dual-luciferase reporter assays. Blocking the glycolytic pathway by the inhibition of glycolytic enzymes ENO2/HK2 suppressed the high proliferation and stem cell-like properties of BC cells induced by ZFP64 overexpression.ConclusionsThese data support that ZFP64 promotes stem cell-like properties and tumorigenesis of BC by activating glycolysis in a transcriptional mechanism.

Neurotoxic mechanisms of dexamethasone in SH-SY5Y neuroblastoma cells: Insights into bioenergetics, oxidative stress, and apoptosis

Despite the known therapeutic uses of dexamethasone (DEX), the specific mechanisms underlying its neurotoxic effects in neuronal cells, particularly in undifferentiated human neuroblastoma (SH-SY5Y) cells, remain inadequately understood. This study aims to elucidate these mechanisms, emphasizing bioenergetics, oxidative stress, and apoptosis, thereby providing novel insights into the cellular vulnerabilities induced by chronic DEX exposure. The findings revealed significant reductions in cell viability, altered membrane integrity with LDH leakage, decreased intracellular ATP production, and the electron transport chain complexes I and III activity inhibition. DEX significantly increased the release of the reactive species and peroxidation of lipids, as well as of Nrf2 expression. At the same time, it simultaneously led to a decline in the activities of the antioxidant catalase and superoxide dismutase enzymes, along with a depletion of glutathione reserves. The apoptosis process was exhibited by a significant elevation of caspases 3 and 8 activities with overexpression of mRNA BAX, inhibition of BCL-2, and a significant upregulation of the BAX/BCL-2 ratio. Assessment of neuronal development genes (GAP43, CAMK2A, CAMK2B, TUBB3, and Wnts) by quantitative PCR assay showed increased expression of CAMK2A, CAMK2B, and Wnt3a with a significant reduction in GAP43 mRNA levels. Collectively, this study proved that DEX was cytotoxic to SH-SY5Y via bioenergetic disruption, mitochondrial dysfunction, oxidative stress, and apoptosis.

Glial swip-10 controls systemic mitochondrial function, oxidative stress, and neuronal viability via copper ion homeostasis

Cuprous copper [Cu(I)] is an essential cofactor for enzymes that support many fundamental cellular functions including mitochondrial respiration and suppression of oxidative stress. Neurons are particularly reliant on mitochondrial production of ATP, with many neurodegenerative diseases, including Parkinson's disease, associated with diminished mitochondrial function. The gene MBLAC1 encodes a ribonuclease that targets pre-mRNA of replication-dependent histones, proteins recently found in yeast to reduce Cu(II) to Cu(I), and when mutated disrupt ATP production, elevates oxidative stress, and severely impacts cell growth. Whether this process supports neuronal and/or systemic physiology in higher eukaryotes is unknown. Previously, we identified swip-10, the putative Caenorhabditis elegans ortholog of MBLAC1, establishing a role for glial swip-10 in limiting dopamine (DA) neuron excitability and sustaining DA neuron viability. Here, we provide evidence from computational modeling that SWIP-10 protein structure mirrors that of MBLAC1 and locates a loss of function coding mutation at a site expected to disrupt histone RNA hydrolysis. Moreover, we find through genetic, biochemical, and pharmacological studies that deletion of swip-10 in worms negatively impacts systemic Cu(I) levels, leading to deficits in mitochondrial respiration and ATP production, increased oxidative stress, and neurodegeneration. These phenotypes can be offset in swip-10 mutants by the Cu(I) enhancing molecule elesclomol and through glial expression of wildtype swip-10. Together, these studies reveal a glial-expressed pathway that supports systemic mitochondrial function and neuronal health via regulation of Cu(I) homeostasis, a mechanism that may lend itself to therapeutic strategies to treat devastating neurodegenerative diseases.

Elucidating the effect of drug-induced mitochondrial dysfunction on insulin signaling and glucose handling in skeletal muscle cell line (C2C12) in vitro.

Efavirenz, tenofovir, rifampicin, simvastatin, lamotrigine and clarithromycin are known potential mitochondrial toxicants. Mitochondrial toxicity has been reported to disrupt the chain of events in the insulin signalling pathway. Considering the upward trajectory of diabetes mellitus prevalence, studies which seek to uncover probable risk factors for developing diabetes should be encouraged. This study aimed to evaluate the intracellular mechanisms leading to the development of insulin resistance in the presence of various conventional pharmacological agents reported as potential mitochondrial toxicants in skeletal muscle cell line. Differentiated C2C12 preparations were exposed to multiple concentrations of efavirenz, tenofovir, rifampicin, simvastatin, lamotrigine, and clarithromycin, separately. Glucose handling was evaluated by observing the changes in insulin-stimulated glucose uptake and assessing the changes in GLUT4 translocation, GLUT4 expression and Akt expression. The changes in mitochondrial function were evaluated by assessing mitochondrial membrane integrity, cellular ATP production, generation of intracellular reactive oxygen species, expression of tafazzin and quantification of medium malonaldehyde. Insulin stimulated glucose uptake was perturbed in C2C12 pre-treated with potential mitotoxicants. Additionally, ATP synthesis, alterations in mitochondrial membrane potential, excessive accumulation of ROS and malonaldehyde were observed in the presence of potential mitotoxicants. Particularly, we observed suppression of proteins involved in the insulin signalling pathway and maintenance of mitochondrial function namely GLUT4, Akt and tafazzin. Mitochondrial toxicants can potentially induce insulin resistance emanating from mitochondrial dysfunction. These new findings will contribute to the understanding of underlying mechanisms involved in the development of insulin resistance linked to mitochondrial dysfunction.

Biocatalytic Clusterzyme Patches Restore Lung Function via Immunomodulation and Mitochondria Protection.

Currently, pulmonary complications such as lung infections during the perioperative period are still the main cause of prolonged hospitalization and death in patients with lung injury due to the lack of effective drugs. Clusterzyme, a kind of artificial enzyme with a high enzyme-like activity and safety profile, exhibits good effects on reducing oxidative stress and immunomodulation. Here, we present the functionalized patches that is administered on the lung airways and rescues the injured organ via clusterzymes. The long-term antioxidant capacity of the patches significantly ameliorated lipopolysaccharide-induced lung function impairment with a significant reduction in lung goblet cell metaplasia and oxidative stress. The inflammatory factors such as cytokines interleukin-1β, interleukin-6, and tumor necrosis factor-α levels decreased by 50%, while the mtDNA copy number increased by 50% and ATP production increased by 100%. Mice lung function was significantly improved, suggesting that the patches can rescue lung injury by modulating oxidative stress and immune responses as well as protecting the mitochondria, providing an avenue for effective intervention of lung injury.

Silk-based nanocomposite hydrogel balances immune homeostasis via targeting mitochondria for diabetic wound healing

Patients with diabetes frequently experience impaired wound healing, a challenge commonly attributed to immune imbalance and oxidative stress; notably, these issues arise from mitochondrial dysfunction. In this study, we fabricate a naturally derived bioactive hydrogel by incorporating resveratrol-loaded mesoporous polydopamine nanoparticles into silk microfibers-reinforced methacrylated silk network (SS/MPDA@RES), which exhibits appropriate injectability, light-curable performance and mechanical strength. It effectively scavenges excessive ROS to protect mitochondria, restore ATP production and remodel redox homeostasis. More importantly, it promotes mitochondrial biogenesis, respiratory capacity and oxidative phosphorylation via the AMPK/SIRT1/PGC-1α signaling axis, thereby reprogramming macrophages to the anti-inflammatory phenotype. In vivo, SS/MPDA@RES hydrogel promotes wound healing in diabetic rats by modulating immunity, inhibiting early inflammation, and accelerating angiogenesis and collagen deposition. Targeting mitochondria to regulate immune and redox homeostasis provides a novel avenue for the design of future tissue regeneration materials, with SS/MPDA@RES emerging as a potential treatment strategy for diabetic wounds.

Abstract PR-13: Disruption of sulfatide metabolism by targeting UGT8 is an actionable metabolic vulnerability for pancreatic cancer early interception

Abstract The existence of asymptomatic precursor lesions that are known to predate invasive pancreatic ductal adenocarcinoma (PDAC) by years provides a compelling rationale for cancer interception efforts. One such precursor is intraductal papillary mucinous neoplasm (IPMN). Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS) imaging of metabolites in tissue sections from resected patient IPMN cases (N=23) and from a KrasG12D/GnasR201C mouse model of IPMN, we have made a discovery of long chain hydroxylated sulfatide species as being selectively enriched in IPMN. Spatial transcriptomics analysis of serial sections from the same IPMN tissues confirmed cognate transcripts, including ceramide galactosyltransferase (CGT, also known as UGT8) and galactose-3-O-sulfotransferase (CST, also known as Gal3St1) enzymes that, respectively, catalyze the addition of galactose from UDP-galactose to ceramide and the O-sulfation of the galactose residue on galactosylceramide (GalCer), to also be highly enriched in IPMN. Functional studies using CRISPR/cas9 UGT8 knockout Kras;Gnas IPMN cells demonstrated that loss of UGT8, the key enzyme that produces the sulfatide precursor GalCer, results in attenuation of sulfatide biosynthesis and impaired mitochondrial function, as evidenced by reduced mitochondrial respiration and ATP production. These changes were met with concomitant decreases in proliferation and invasiveness, and increased susceptibility to intrinsic apoptosis. Targeting of sulfatide metabolism using a selective small molecule inhibitor of UGT8 suppressed sulfatide biosynthesis, induced ceramide-mediated compensatory mitophagy, and subsequent apoptosis in Kras;Gnas IPMN cells. In vivo, UGT8 inhibition suppressed tumor growth in an IPMN allograft model. In conclusion, our work identifies enhanced sulfatide metabolism as an early metabolic alteration in cystic pre-cancerous lesions of the pancreas that persists through invasive neoplasia and represents an actionable vulnerability for PDAC early interception. Citation Format: Riccardo Ballarò, Yihui Chen, Fredrik I Thege, Rongzhang Dou, Jimin Min, Michele Yip-Schneider, Jianjun Zhang, Ranran Wu, Ehsan Irajizad, Yuki Makino, Kimal I Rajapakshe, Mark W Hurd, Ricardo A León-Letelier, Edwin Ostrin, Jody Vykoukal, Jennifer B Dennison, Kim-Anh Do, Samir Hanash, Robert A Wolff, Paola A Guerrero, Michael P Kim, C Max Schmidt, Anirban Maitra, Johannes F Fahrmann. Disruption of sulfatide metabolism by targeting UGT8 is an actionable metabolic vulnerability for pancreatic cancer early interception [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr PR-13.

Abstract C035: MAGEA6 Oncogene Upregulates MAPK and AMPK Signaling Pathways in Pancreatic Cancer Cells to Promote Survival under Nutrient Stress: Resistance to Glycolysis Inhibition and Increased Susceptibility to Glutamine Depletion

Abstract Introduction: Melanoma-associated antigens (MAGEs) are linked to aggressive disease progression and treatment resistance in many cancers, but their role in pancreatic cancer is not well understood. Our preliminary TCGA data analysis suggested that 10% of pancreatic tumors express MAGEA3/6 and potentially help pancreatic cancer cells survive and grow under nutrient stress. This study aims to uncover the molecular mechanisms of MAGEA3/6 function in pancreatic cancer cell metabolism and disease progression under nutrient-poor conditions. Methods: To understand the role of highly homologous genes MAGEA3 and MAGEA6 in pancreatic cancer, we expressed them in highly glycolytic MIA PaCa-2 pancreatic cancer cells. Cells were then exposed to cancer-related nutritional stressors, including glycolysis inhibition by 2-deoxy-D-glucose (2DG) treatment and glutamine depletion. We analyzed the effect of MAGEA6 expression on cell viability and cell metabolism by Alamar Blue viability assay (BioRad), Seahorse (Agilent), Phenotype MicroArray Mammalian analysis (Biolog), transmission electron microscopy (TEM), and RNA sequencing. To confirm our results, we performed loss-of- function studies in MAGEA3/6-positive cells, including PANC1. Results: We found that, compared to control GFP-expressing cells, MAGEA6-expressing MIA PaCa-2 cells were resistant to glycolysis inhibition with 2-DG. In contrast, they were more susceptible to glutamine depletion, suggesting the important role of MAGEA3/6 in metabolic phenotype and adaptations of pancreatic cancer cells. Further, we showed that MAGEA6-expressing cells exhibited increased ATP production and mitochondrial oxidative phosphorylation, especially under 2DG stress. After 48 hours of 2DG treatment, TEM images revealed significant differences in nuclear, mitochondrial, and ribosomal structures in MAGEA6-cells, further suggesting MAGEA6's role in metabolic adaptation. The Phenotype MicroArray assay demonstrated that α-D-Glucose is the primary nutrient source consumed by both GFP and MAGEA6-expressing cells among the 93 nutrients tested. Additionally, A6 cells utilize Pyruvic Acid as an alternative nutrient source more than GFP cells. To uncover molecular underpinning, we performed RNA sequencing and found that MAGEA6 expression affects transcriptome under glutamine depletion and 2DG treatment. Intriguingly, one of the major differentially regulated biological processes was associated with the upregulation of several signaling pathways, including MAPK and AMPK. Conclusion: Our findings suggest that in pancreatic cancer, MAGEA6 recruits stress and growth factor- dependent MAPK and AMPK pathways to overcome glycolysis inhibition, even in glutamine- depleted conditions, providing a growth advantage. This implies that patients with MAGEA6- positive tumors may benefit from combination therapy targeting metabolism and signaling pathways. Citation Format: Sima Tozandehjani, Barbara Breznik, Klementina Fon Tacer, Miloš Vittori, Juan Sebastian Solano, Sara Uhan. MAGEA6 Oncogene Upregulates MAPK and AMPK Signaling Pathways in Pancreatic Cancer Cells to Promote Survival under Nutrient Stress: Resistance to Glycolysis Inhibition and Increased Susceptibility to Glutamine Depletion [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C035.

BRUCE liver-deficiency potentiates MASLD/MASH in PTEN liver-deficient background by impairment of mitochondrial metabolism in hepatocytes and activation of STAT3 signaling in hepatic stellate cells.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is currently the most common liver disease, affecting up to 25% of people worldwide, featuring excessive fat accumulation in hepatocytes. Its advanced form, metabolic dysfunction-associated steatohepatitis (MASH), is a serious disease with hepatic inflammation and fibrosis, increasing the need for liver transplants. However, the pathogenic mechanism of MASLD and MASH is not fully understood. We reported that BRUCE ( BIRC6) is a liver cancer suppressor and is downregulated in MASLD/MASH patient liver specimens, though the functional role of BRUCE in MASLD/MASH remains to be elucidated. To this end, we generated liver-specific double KO (DKO) mice of BRUCE and PTEN, a major tumor suppressor and MASLD/MASH suppressor. By comparing liver histopathology among 2-3-month-old mice, there were no signs of MASLD or MASH in BRUCE liver-KO mice and only onset of steatosis in PTEN liver-KO mice. Interestingly, DKO mice had developed robust hepatic steatosis with inflammation and fibrosis. Further analysis of mitochondrial function with primary hepatocytes found moderate reduction of mitochondrial respiration, ATP production and fatty acid oxidation in BRUCE KO and the greatest reduction in DKO hepatocytes. Moreover, aberrant activation of pro-fibrotic STAT3 signaling was found in hepatic stellate cells (HSCs) in DKO mice which was prevented by administered STAT3-specific inhibitor (TTI-101). Collectively, the data demonstrates by maintaining mitochondrial metabolism BRUCE works in concert with PTEN to suppress the pro-fibrogenic STAT3 activation in HSCs and consequentially prevent MASLD/MASH. The findings highlight BRUCE being a new co-suppressor of MASLD/MASH.

Alterations in the molecular regulation of mitochondrial metabolism in human alveolar epithelial cells in response to cigarette- and heated tobacco product emissions

Mitochondrial abnormalities in lung epithelial cells have been associated with chronic obstructive pulmonary disease (COPD) pathogenesis. Cigarette smoke (CS) can induce alterations in the molecular pathways regulating mitochondrial function in lung epithelial cells. Recently, heated tobacco products (HTPs) have been marketed as harm reduction products compared with regular cigarettes. However, the effects of HTP emissions on human alveolar epithelial cell metabolism and on the molecular mechanisms regulating mitochondrial content and function are unclear. In this study, human alveolar epithelial cells (A549) were exposed to cigarette or HTP emissions in the form of liquid extracts. The oxygen consumption rate of differently exposed cells was measured, and mRNA and protein abundancy of key molecules involved in the molecular regulation of mitochondrial metabolism were assessed. Furthermore, we used a mitophagy detection probe to visualize mitochondrial breakdown over time in response to the extracts. Both types of extracts induced increases in basal-, maximal- and spare respiratory capacity, as well as in cellular ATP production. Moreover, we observed alterations in the abundancy of regulatory molecules controlling mitochondrial biogenesis and mitophagy. Mitophagy was not significantly altered in response to the extracts, as no significant differences compared to vehicle-treated cells were observed.

Asperuloside activates hepatic NRF2 signaling to stimulate mitochondrial metabolism and restore lipid homeostasis in high fat diet-induced MAFLD

BackgroundNutrient overload predisposes the development of metabolic dysfunction-associated fatty liver disease (MAFLD). However, there are no specific pharmacological therapies for MAFLD. Asperuloside (ASP), an iridoid glycoside extracted from Eucommia ulmoides leaves, can alleviate obesity and MAFLD. However, the underlying mechanism and pharmacological effects of ASP on ameliorating MAFLD remain largely investigated. This study aimed to explore the effects of ASP in ameliorating MAFLD and to unravel its underlying mechanism using a high fat diet-induced MAFLD mice model. MethodsSix-week-old C57BL/6 male mice were fed a high fat diet for 12 weeks to induce MAFLD, followed by daily ASP treatment (50 mg/kg via oral gavage) for 7 weeks. HepG2 cells were used for in vitro studies. Nuclear factor erythroid 2-related factor 2 (Nrf2) inhibitor, ML385, was employed to explore the mechanisms of ASP's action. ResultsASP stimulated lipolysis and inhibited de novo lipogenesis, contributing to alleviating lipid deposition in obese mice livers and HepG2 cells. ASP restored ATP production and reversed the impairments of mitochondrial energetics and biogenesis in obese mice livers and HepG2 cells. ASP attenuated oxidative stress in obese mice livers and HepG2 cells, exhibiting its antioxidant value. Impressively, ASP significantly promotes Nrf2 nuclear translocation and Nrf2/ARE binding, thereby activating Nrf2/ARE pathway in obese mice livers and HepG2 cells, demonstrating its potential as a hepatic Nrf2 activator. Nrf2 inhibition abolishes the protective effects of ASP against lipid deposition, oxidative stress and mitochondrial dysfunction, emphasizing the critical role of ASP-activated hepatic Nrf2 signaling in ameliorating MAFLD. ConclusionsThis study provides the first line of evidence demonstrating the pivotal role of ASP-stimulated Nrf2 activation in alleviating MAFLD, emphasizing its potential as a hepatic Nrf2 activator targeting fatty liver diseases. These findings offer new evidence of ASP-stimulated mitochondrial metabolism and lipolysis in MAFLD, paving the way for the development of ASP as a therapeutic agent and dietary supplement to attenuate MAFLD progression.