Pyruvate Dehydrogenase Kinase Research Articles

Pyruvate dehydrogenase kinase 1–dependent metabolic reprogramming: A promising target for postmenopausal osteoporosis treatment

Postmenopausal osteoporosis (PMOP) is a classic endocrine disorder characterized by an imbalance between bone formation and bone resorption. Abnormal glucose metabolic reprogramming has been widely explored in endocrine disorders, but its role in PMOP has not been elucidated. Icariin (ICA), as a bioactive component of the traditional Chinese medicine Epimedium grandiflorum, has been testified to be effective for PMOP treatment, but its effects on glucose metabolism are poorly studied. In this study, pyruvate dehydrogenase was proved to be a key regulator of the metabolic switch in PMOP and the efficacy of ICA. The augmentation of pyruvate dehydrogenase subunit alpha (PDHA) pSer232, which was excited in osteoclasts; the decreased expression of citrate synthase; elevated expression of lactate dehydrogenase; and changes in the pyruvate, lactate, and citrate pools all indicated the preference for aerobic glycolysis in PMOP. Further study showed that the expression and activity of pyruvate dehydrogenase kinase 1 (PDK1) which regulated the phosphorylation status of PDHA Ser232 were both increased in ovariectomized rats. Furthermore, the genetic knockdown of PDK1 and pharmaceutical inhibition of PDK1 markedly suppressed osteoclastogenesis. Meanwhile, ICA might reverse metabolic reprogramming by inhibiting PDK1. In conclusion, this study revealed that PDK1-dependent metabolic reprogramming is a potential therapeutic target for PMOP treatment. ICA alleviates PMOP by inhibiting PDK1 in osteoclasts, indicating its potential for clinical use.

Cardiomyocyte Pdk4 response is associated with metabolic maladaptation in aging.

Ischemic heart disease (IHD) is the leading cause of death, with age range being the primary factor for development. The mechanisms by which aging increases vulnerability to ischemic insult are not well understood. We aim to use single-cell RNA sequencing to discover transcriptional differences in various cell types between aged and young mice, which may contribute to aged-related vulnerability to ischemic insult. Utilizing 10× Genomics Single-Cell RNA sequencing, we were able to complete bioinformatic analysis to identity novel differential gene expression. During the analysis of our collected samples, we detected Pyruvate Dehydrogenase Kinase 4 (Pdk4) expression to be remarkably differentially expressed. Particularly in cardiomyocyte cell populations, Pdk4 was found to be significantly upregulated in the young mouse population compared to the aged mice under ischemic/reperfusion conditions. Pdk4 is responsible for inhibiting the enzyme pyruvate dehydrogenase, resulting in the regulation of glucose metabolism. Due to decreased Pdk4 expression in aged cardiomyocytes, there may be an increased reliance on glucose oxidization for energy. Through biochemical metabolomics analysis, it was observed that there is a greater abundance of pyruvate in young hearts in contrast to their aged counterparts, indicating less glycolytic activity. We believe that Pdk4 response provides valuable insight towards mechanisms that allow for the young heart to handle ischemic insult stress more effectively than the aged heart.

Discovery of the 3-Amino-1,2,4-triazine-Based Library as Selective PDK1 Inhibitors with Therapeutic Potential in Highly Aggressive Pancreatic Ductal Adenocarcinoma.

Pyruvate dehydrogenase kinases (PDKs) are serine/threonine kinases, that are directly involved in altered cancer cell metabolism, resulting in cancer aggressiveness and resistance. Dichloroacetic acid (DCA) is the first PDK inhibitor that has entered phase II clinical; however, several side effects associated with weak anticancer activity and excessive drug dose (100 mg/kg) have led to its limitation in clinical application. Building upon a molecular hybridization approach, a small library of 3-amino-1,2,4-triazine derivatives has been designed, synthesized, and characterized for their PDK inhibitory activity using in silico, in vitro, and in vivo assays. Biochemical screenings showed that all synthesized compounds are potent and subtype-selective inhibitors of PDK. Accordingly, molecular modeling studies revealed that a lot of ligands can be properly placed inside the ATP-binding site of PDK1. Interestingly, 2D and 3D cell studies revealed their ability to induce cancer cell death at low micromolar doses, being extremely effective against human pancreatic KRAS mutated cancer cells. Cellular mechanistic studies confirm their ability to hamper the PDK/PDH axis, thus leading to metabolic/redox cellular impairment, and to ultimately trigger apoptotic cancer cell death. Remarkably, preliminary in vivo studies performed on a highly aggressive and metastatic Kras-mutant solid tumor model confirm the ability of the most representative compound 5i to target the PDH/PDK axis in vivo and highlighted its equal efficacy and better tolerability profile with respect to those elicited by the reference FDA approved drugs, cisplatin and gemcitabine. Collectively, the data highlights the promising anticancer potential of these novel PDK-targeting derivatives toward obtaining clinical candidates for combatting highly aggressive KRAS-mutant pancreatic ductal adenocarcinomas.

Thermal Titration Molecular Dynamics (TTMD): Not Your Usual Post-Docking Refinement.

Molecular docking is one of the most widely used computational approaches in the field of rational drug design, thanks to its favorable balance between the rapidity of execution and the accuracy of provided results. Although very efficient in exploring the conformational degrees of freedom available to the ligand, docking programs can sometimes suffer from inaccurate scoring and ranking of generated poses. To address this issue, several post-docking filters and refinement protocols have been proposed throughout the years, including pharmacophore models and molecular dynamics simulations. In this work, we present the first application of Thermal Titration Molecular Dynamics (TTMD), a recently developed method for the qualitative estimation of protein-ligand unbinding kinetics, to the refinement of docking results. TTMD evaluates the conservation of the native binding mode throughout a series of molecular dynamics simulations performed at progressively increasing temperatures with a scoring function based on protein-ligand interaction fingerprints. The protocol was successfully applied to retrieve the native-like binding pose among a set of decoy poses of drug-like ligands generated on four different pharmaceutically relevant biological targets, including casein kinase 1δ, casein kinase 2, pyruvate dehydrogenase kinase 2, and SARS-CoV-2 main protease.

The Role of Pyruvate Metabolism in Mitochondrial Quality Control and Inflammation.

Pyruvate metabolism, a key pathway in glycolysis and oxidative phosphorylation, is crucial for energy homeostasis and mitochondrial quality control (MQC), including fusion/fission dynamics and mitophagy. Alterations in pyruvate flux and MQC are associated with reactive oxygen species accumulation and Ca2+ flux into the mitochondria, which can induce mitochondrial ultrastructural changes, mitochondrial dysfunction and metabolic dysregulation. Perturbations in MQC are emerging as a central mechanism for the pathogenesis of various metabolic diseases, such as neurodegenerative diseases, diabetes and insulin resistance-related diseases. Mitochondrial Ca2+ regulates the pyruvate dehydrogenase complex (PDC), which is central to pyruvate metabolism, by promoting its dephosphorylation. Increase of pyruvate dehydrogenase kinase (PDK) is associated with perturbation of mitochondria-associated membranes (MAMs) function and Ca2+ flux. Pyruvate metabolism also plays an important role in immune cell activation and function, dysregulation of which also leads to insulin resistance and inflammatory disease. Pyruvate metabolism affects macrophage polarization, mitochondrial dynamics and MAM formation, which are critical in determining macrophage function and immune response. MAMs and MQCs have also been intensively studied in macrophage and T cell immunity. Metabolic reprogramming connected with pyruvate metabolism, mitochondrial dynamics and MAM formation are important to macrophages polarization (M1/M2) and function. T cell differentiation is also directly linked to pyruvate metabolism, with inhibition of pyruvate oxidation by PDKs promoting proinflammatory T cell polarization. This article provides a brief review on the emerging role of pyruvate metabolism in MQC and MAM function, and how dysfunction in these processes leads to metabolic and inflammatory diseases.

1,5-Anhydroglucitol promotes pre-B acute lymphocytic leukemia progression by driving glycolysis and reactive oxygen species formation

BackgroundPrecursor B-cell acute lymphoblastic leukemia (pre-B ALL) is the most common hematological malignancy in children. Cellular metabolic reorganization is closely related to the progression and treatment of leukemia. We found that the level of 1,5-anhydroglucitol (1,5-AG), which is structurally similar to glucose, was elevated in children with pre-B ALL. However, the effect of 1,5-AG on pre-B ALL was unclear. Here, we aimed to reveal the roles and mechanisms of 1,5-AG in pre-B ALL progression.MethodsThe peripheral blood plasma level of children with initial diagnosis of pre-B ALL and that of healthy children was measured using untargeted metabolomic analysis. Cell Counting Kit-8 assay, RNA sequencing, siRNA transfection, real-time quantitative PCR, and western blot were performed using pre-B ALL cell lines Reh and HAL-01. Cell cycle, cell apoptosis, ROS levels, and the positivity rate of CD19 were assessed using flow cytometry. Oxygen consumption rates and extracellular acidification rate were measured using XFe24 Extracellular Flux Analyzer. The lactate and nicotinamide adenine dinucleotide phosphate levels were measured using kits. The effect of 1,5-AG on pre-B ALL progression was verified using the In Vivo Imaging System in a xenotransplantation leukemia model.ResultsWe confirmed that 1,5-AG promoted the proliferation, viability, and intracellular glycolysis of pre-B ALL cells. Mechanistically, 1,5-AG promotes glycolysis while inhibiting mitochondrial respiration by upregulating pyruvate dehydrogenase kinase 4 (PDK4). Furthermore, high levels of intracellular glycolysis promote pre-B ALL progression by activating the reactive oxygen species (ROS)-dependent mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway. Conversely, N-acetylcysteine or vitamin C, an antioxidant, effectively inhibited 1,5-AG-mediated progression of leukemia cells.ConclusionsOur study reveals a previously undiscovered role of 1,5-AG in pre-B ALL, which contributes to an in-depth understanding of anaerobic glycolysis in the progression of pre-B ALL and provides new targets for the clinical treatment of pre-B ALL.

Resveratrol inhibits multiple organ injury in preeclampsia rat model.

To investigate the effects of resveratrol on multiple organ injury and energy metabolism and its possible mechanism in preeclampsia model. A total of 45 clean-grade female adults Sprague Dawley (SD) rats (weight 270-320 g) were randomly divided into three groups: a control group, preeclampsia group (PE), and Preeclampsia with resveratrol treatment group (RE). Preeclampsia was induced in rats by administering 200 mg/kg/day L-NAME. Expression levels of TNF-α and IL-6 in the lungs and kidney tissues were analysed by ELISA, while the activity of superoxide dismutase (SOD) and malondialdehyde (MDA) was determined by biochemical assays. The levels of lactic acid and pyruvate were detected using biochemical assays, while the epinephrine level in the kidney and heart tissues was determined by the ELISA method. Reverse transcription polymerase chain reaction and the western blotting were used to detect the expression of pyruvate dehydrogenase kinase 4 (PDK4) in the myocardial tissues. We found that resveratrol treatment inhibited the levels of IL-6, TNF-α, and MDA in the lungs and kidney tissues, while the SOD activity was increased. Treatment with resveratrol reduced the levels of lactic acid, pyruvate, and epinephrine in the kidney and heart tissues. Furthermore, resveratrol treatment significantly increases the expression of PDK4 myocardial tissues in RE group compared to PE group. Resveratrol may inhibit the release of tissue inflammatory factors, regulate the body's energy metabolism, and ultimately protect tissue damage caused during Preeclampsia.

Inhibition of phosphoglycerate kinase 1 attenuates autoimmune myocarditis by reprogramming CD4+ T cell metabolism.

CD4+ T cells are the major drivers of cardiac-specific autoimmunity in myocarditis, specifically Th1, Treg, and most significant Th17 cells. But the molecular mechanisms of their activation remain unclear. We aimed to elucidate the regulatory role of phosphoglycerate kinase 1 (PGK1) in CD4+ T cells and experimental autoimmune myocarditis (EAM). EAM was induced in BALB/c mice by subcutaneous injections with alpha myosin heavy chain peptide emulsified in complete Freund's adjuvant. Single-cell sequencing analysis found that glycolysis and PGK1 expression were elevated in cardiac CD4+ T and Th17 cells from myocarditis mice. Mice treated with PGK1 inhibitor NG52 showed less cardiac inflammation and fibrosis and better contractile function, as well as reduced cardiac infiltrating Th17 and Th1 cells and increased proportion of Treg. NG52 suppressed CD4+ T cell activation and differentiation of mice and myocarditis patients in vitro. Mechanistically, inhibition of PGK1 suppressed glycolytic activity and decreased pyruvate dehydrogenase kinase 1 (PDHK1) phosphorylation, thereby increasing reactive oxygen species (ROS) production in mitochondria and thus preventing Th17 cell differentiation. PGK1 may act as a key metabolic regulator of CD4+ T cell differentiation and regulates Th17 cell differentiation by regulating glycolysis and the PDHK1-ROS axis. Targeting PGK1 might be a promising strategy for the treatment of myocarditis.

Changes in gene expression and enzyme activity related to glucose metabolism in the livers of Brandt's voles (Lasiopodomys brandtii) exposed to hypoxia

Brandt's vole (Lasiopodomys brandtii) is a hypoxia-tolerant species, and the metabolic characteristics of hypoxia-tolerant species have become a focus of recent research. However, insights into the anaerobic and aerobic metabolism of the livers of Brandt's voles under hypoxia remain limited. In this study, Brandt's voles and hypoxia-intolerant Kunming mice (Mus musculus, control species) were exposed to hypoxia conditions (Brandt's voles, 10% and 7.5% O2; Kunming mice, 10% O2) for 24 h, and changes in gene expression and enzyme activity related to anaerobic and aerobic metabolism in the livers were evaluated. Phosphofructokinase 1 (PFK1), phosphofructokinase 2 (PFK2), pyruvate kinase muscle (PKM), hexokinase 2 (HK2), and lactate dehydrogenase (LDH) related to anaerobic metabolism in the livers of Brandt's voles were increased under 7.5% O2. Regarding gene expression and enzyme activity for aerobic metabolism in Brandt's voles under 7.5% and 10% O2, pyruvate dehydrogenase kinase 1 (PDK1) expression was up-regulated, and succinate dehydrogenase (SDH) activity was decreased. In the livers of Kunming mice, gene expression related to anaerobic and aerobic metabolism was increased at the late stage of 10% O2, and SDH activity was enhanced at 6 h and reduced at 18 h. In addition, PFK1,PKM, PDK1 expression and SDH activity in Brandt's voles were significantly correlated with HIF-1a expression. PFK1, PKM, LDHand PDK1 expression in Kunming mice were significantly correlated with HIF-1a expression. These findings indicate that the livers of Brandt's voles have a certain tolerance to hypoxia, and metabolic changes play important roles in hypoxia tolerance.

Acquired disorders of mitochondrial metabolism and dynamics in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is an orphan disease of the cardiopulmonary unit that reflects an obstructive pulmonary vasculopathy and presents with hypertrophy, inflammation, fibrosis, and ultimately failure of the right ventricle (RVF). Despite treatment using pulmonary hypertension (PH)-targeted therapies, persistent functional impairment reduces the quality of life for people with PAH and death from RVF occurs in approximately 40% of patients within 5 years of diagnosis. PH-targeted therapeutics are primarily vasodilators and none, alone or in combination, are curative. This highlights a need to therapeutically explore molecular targets in other pathways that are involved in the pathogenesis of PAH. Several candidate pathways in PAH involve acquired mitochondrial dysfunction. These mitochondrial disorders include: 1) a shift in metabolism related to increased expression of pyruvate dehydrogenase kinase and pyruvate kinase, which together increase uncoupled glycolysis (Warburg metabolism); 2) disruption of oxygen-sensing related to increased expression of hypoxia-inducible factor 1α, resulting in a state of pseudohypoxia; 3) altered mitochondrial calcium homeostasis related to impaired function of the mitochondrial calcium uniporter complex, which elevates cytosolic calcium and reduces intramitochondrial calcium; and 4) abnormal mitochondrial dynamics related to increased expression of dynamin-related protein 1 and its binding partners, such as mitochondrial dynamics proteins of 49kDa and 51kDa, and depressed expression of mitofusin 2, resulting in increased mitotic fission. These acquired mitochondrial abnormalities increase proliferation and impair apoptosis in most pulmonary vascular cells (including endothelial cells, smooth muscle cells and fibroblasts). In the RV, Warburg metabolism and induction of glutaminolysis impairs bioenergetics and promotes hypokinesis, hypertrophy, and fibrosis. This review will explore our current knowledge of the causes and consequences of disordered mitochondrial function in PAH.

LncRNA MEG3 Promotes PDK4/GSK-3β/β-Catenin Axis in MEFs by Targeting miR-532-5p.

Studies reported the positive and negative osteogenic effects of MEG3 in mesenchymal stem cells (MSCs). This study aims at clarifying the osteogenic potential of MEG3 and the underlying mechanism. Bone morphogenetic protein 9- (BMP9-) transfected MSCs were recruited as an osteogenic model in vitro, and ectopic bone formation were used in vivo to explore the effect of MEG3 on osteogenesis. We found that overexpression of MEG3 facilitated BMP9-induced osteogenic markers, ALP activities, and matrix mineralization. However, knockdown of MEG3 attenuated BMP9-induced osteogenic markers. MEG3 increased the phosphorylation of GSK-3β and the protein level of β-catenin. Pyruvate dehydrogenase kinase 4 (PDK4) can also combine with GSK-3β and increase the latter phosphorylation. Moreover, MEG3 increased the mRNA level of PDK4. The ceRNA analysis showed that MEG3 may regulate the expression of PDK4 via microRNA 532-5p (miR-532-5p). The MEG3-enhanced GSK-3β/β-catenin axis can be attenuated by miR-532-5p, and miR-532-5p inhibitor partly rescued endogenous PDK4 and MEG3-mediated expression of PDK4. MEG3 may potentiate PDK4 and GSK-3β/β-catenin by inhibiting miR-532-5p.

Analysis of a genetic region affecting mouse body weight.

Genetic factors affect an individual's risk of developing obesity, but in most cases each genetic variant has a small effect. Discovery of genes that regulate obesity may provide clues about its underlying biological processes and point to new ways the disease can be treated. Preclinical animal models facilitate genetic discovery in obesity because environmental factors can be better controlled compared with the human population. We studied inbred mouse strains to identify novel genes affecting obesity and glucose metabolism. BTBR T+ Itpr3tf/J (BTBR) mice are fatter and more glucose intolerant than C57BL/6J (B6) mice. Prior genetic studies of these strains identified an obesity locus on chromosome 2. Using congenic mice, we found that obesity was affected by a ∼316 kb region, with only two known genes, pyruvate dehydrogenase kinase 1 (Pdk1) and integrin α 6 (Itga6). Both genes had mutations affecting their amino acid sequence and reducing mRNA levels. Both genes have known functions that could modulate obesity, lipid metabolism, insulin secretion, and/or glucose homeostasis. We hypothesized that genetic variation in or near Pdk1 or Itga6 causing reduced Pdk1 and Itga6 expression would promote obesity and impaired glucose tolerance. We used knockout mice lacking Pdk1 or Itga6 fed an obesigenic diet to test this hypothesis. Under the conditions we studied, we were unable to detect an individual contribution of either Pdk1 or Itga6 to body weight. During our studies, with conditions outside our control, we were unable to reproduce some of our previous body weight data. However, we identified a previously unknown role for Pdk1 in cardiac cholesterol metabolism providing the basis for future investigations. The studies described in this paper highlight the importance and the challenge using physiological outcomes to study obesity genes in mice.

Interaction between Butyrate and Tumor Necrosis Factor α in Primary Rat Colonocytes.

Butyrate, a short-chain fatty acid, is utilized by the gut epithelium as energy and it improves the gut epithelial barrier. More recently, it has been associated with beneficial effects on immune and cardiovascular homeostasis. Conversely, tumor necrosis factor alpha (TNFα) is a pro-inflammatory and pro-hypertensive cytokine. While butyrate and TNFα are both linked with hypertension, studies have not yet addressed their interaction in the colon. Here, we investigated the capacity of butyrate to modulate a host of effects of TNFα in primary rodent colonic cells in vitro. We measured ATP levels, cell viability, mitochondrial membrane potential (MMP), reactive oxygen species (ROS), mitochondrial oxidative phosphorylation, and glycolytic activity in colonocytes following exposure to either butyrate or TNFα, or both. To address the potential mechanisms, transcripts related to oxidative stress, cell fate, and cell metabolism (Pdk1, Pdk2, Pdk4, Spr, Slc16a1, Slc16a3, Ppargc1a, Cs, Lgr5, Casp3, Tnfr2, Bax, Bcl2, Sod1, Sod2, and Cat) were measured, and untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed to profile the metabolic responses of colonocytes following exposure to butyrate and TNFα. We found that both butyrate and TNFα lowered cellular ATP levels towards a quiescent cell energy phenotype, characterized by decreased oxygen consumption and extracellular acidification. Co-treatment with butyrate ameliorated TNFα-induced cytotoxicity and the reduction in cell viability. Butyrate also opposed the TNFα-mediated decrease in MMP and mitochondrial-to-intracellular calcium ratios, suggesting that butyrate may protect colonocytes against TNFα-induced cytotoxicity by decreasing mitochondrial calcium flux. The relative expression levels of pyruvate dehydrogenase kinase 4 (Pdk4) were increased via co-treatment of butyrate and TNFα, suggesting the synergistic inhibition of glycolysis. TNFα alone reduced the expression of monocarboxylate transporters slc16a1 and slc16a3, suggesting effects of TNFα on butyrate uptake into colonocytes. Of the 185 metabolites that were detected with LC-MS, the TNFα-induced increase in biopterin produced the only significant change, suggesting an alteration in mitochondrial biogenesis in colonocytes. Considering the reports of elevated colonic TNFα and reduced butyrate metabolism in many conditions, including in hypertension, the present work sheds light on cellular interactions between TNFα and butyrate in colonocytes that may be important in understanding conditions of the colon.

PKM2/PDK1 dual-targeted shikonin derivatives restore the sensitivity of EGFR-mutated NSCLC cells to gefitinib by remodeling glucose metabolism

Pyruvate kinase 2 (PKM2) and pyruvate dehydrogenase kinase 1 (PDK1) are two key enzymes in tumor glucose metabolism pathway that not only promote tumor growth and proliferation through accelerating aerobic glycolysis, but also contribute to drug resistance of non-small cell lung cancer (NSCLC). Considering that targeting PKM2 or PDK1 alone seems insufficient to remodel abnormal glucose metabolism to achieve significant antitumor activity, we proposed a “two-step approach” that regulates PKM2 and PDK1 synchronously. Firstly, we found that the combination of ML265 (PKM2 activator) and AZD7545 (PDK1 inhibitor) could synergistically inhibit proliferation and induce apoptosis in H1299 cells. Base on this, we designed a series of novel shikonin (SK) thioether derivatives as PKM2/PDK1 dual-target agents, among which the most potent compound E5 featuring a 2-methyl substitution on the benzene ring exerted significantly increased inhibitory activity toward EGFR mutant NSCLC cell H1975 (IC50 = 1.51 μmol/L), which was 3 and 17-fold more active than the lead compound SK (IC50 = 4.56 μmol/L) and the positive control gefitinib (IC50 = 25.56 μmol/L), respectively. Additionally, E5 also showed good anti-tumor activity in xenografted mouse models, with significantly lower toxicity side effects than SK. Moreover, E5 also inhibited the entry of PKM2 into nucleus to regulate the transcriptional activation of oncogenes, thus restoring the sensitivity of H1975 cell to gefitinib. Collectively, these data demonstrate that E5, a dual inhibitor of PKM2/PDK1, may be a promising adjunct to gefitinib in the treatment of EGFR-TKIs resistant NSCLC, deserving further investigation.

1,2,4-Amino-triazine derivatives as pyruvate dehydrogenase kinase inhibitors: Synthesis and pharmacological evaluation

Among the different hallmarks of cancer, deregulation of cellular metabolism turned out to be an essential mechanism in promoting cancer resistance and progression. The pyruvate dehydrogenase kinases (PDKs) are well known as key regulators in cells metabolic process and their activity was found to be overexpressed in different metabolic alerted types of cancer, including the high aggressive pancreatic ductal adenocarcinoma (PDAC). To date few PDK inhibitors have been reported, and the different molecules developed are characterized by structural chemical diversity. In an attempt to find novel classes of potential PDK inhibitors, the molecular hybridization approach, which combine two or more active scaffolds in a single structure, was employed. Herein we report the synthesis and the pharmacological evaluation of the novel hybrid molecules, characterized by the fusion of three different pharmacophoric sub-units such as 1,2,4-amino triazines, 7-azaindoles and indoles, in a single structure. The synthesized derivatives demonstrated a promising ability in hampering the enzymatic activity of PDK1 and 4, further confirmed by docking studies. Interestingly, these derivatives retained a strong antiproliferative activity against pancreatic cancer cells either in 2D and 3D models. Mechanistic studies in highly aggressive PDAC cells confirmed their ability to hamper PDK axis and to induce cancer cell death by apoptosis. Moreover, in vivo translational studies in a murine syngeneic solid tumor model confirmed the ability of the most representative compounds to target the PDK system and highlight the ability to reduce the tumor growth without inducing substantial body weight changes in the treated mice.

The Link between Mitochondrial Dysfunction and Sarcopenia: An Update Focusing on the Role of Pyruvate Dehydrogenase Kinase 4.

Sarcopenia, defined as a progressive loss of muscle mass and function, is typified by mitochondrial dysfunction and loss of mitochondrial resilience. Sarcopenia is associated not only with aging, but also with various metabolic diseases characterized by mitochondrial dyshomeostasis. Pyruvate dehydrogenase kinases (PDKs) are mitochondrial enzymes that inhibit the pyruvate dehydrogenase complex, which controls pyruvate entry into the tricarboxylic acid cycle and the subsequent adenosine triphosphate production required for normal cellular activities. PDK4 is upregulated in mitochondrial dysfunction-related metabolic diseases, especially pathologic muscle conditions associated with enhanced muscle proteolysis and aberrant myogenesis. Increases in PDK4 are associated with perturbation of mitochondria-associated membranes and mitochondrial quality control, which are emerging as a central mechanism in the pathogenesis of metabolic disease-associated muscle atrophy. Here, we review how mitochondrial dysfunction affects sarcopenia, focusing on the role of PDK4 in mitochondrial homeostasis. We discuss the molecular mechanisms underlying the effects of PDK4 on mitochondrial dysfunction in sarcopenia and show that targeting mitochondria could be a therapeutic target for treating sarcopenia.

Aa-Z2 triggers ROS-induced apoptosis of osteosarcoma by targeting PDK-1

BackgroundOsteosarcoma (OS) is the most frequent cancer derived from bone, and the prognosis of OS is poor. Metabolic alterations have been previously reported to contribute to the development of OS, and arsenic compounds have been suggested to exhibit strong anti-OS effects. However, few studies have described the therapeutic efficiency of arsenic compounds by targeting metabolism in OS.MethodsHere, we presented a novel organo-arsenic compound, Aa-Z2, and its antitumour efficacy against OS both in vitro and in vivo.ResultsAa-Z2 induced OS cell apoptosis, G2/M phase arrest, and autophagy through the accumulation of reactive oxygen species (ROS). Elevated ROS functioned by promoting the mitochondrial-dependent caspase cascade and attenuating the PI3K/Akt/mTOR signalling pathway. N-acetylcysteine (NAC), a kind of ROS scavenger, could reverse the effects of Aa-Z2 treatment on 143B and HOS cells. Specifically, by targeting pyruvate dehydrogenase kinase 1 (PDK-1), Aa-Z2 induced changes in mitochondrial membrane potential and alterations in glucose metabolism to accumulate ROS. Overexpression of PDK-1 could partially desensitize OS cells to Aa-Z2 treatment. Importantly, Aa-Z2 suppressed tumour growth in our xenograft osteosarcoma model.ConclusionThe study provides new insights into the mechanism of Aa-Z2-related metabolic alterations in OS inhibition, as well as pharmacologic evidence supporting the development of metabolism-targeting therapeutics.

Synthesis of N‐(2‐(tert‐Butylamino)‐2‐oxoethyl)‐2,2‐dichloro‐N‐aryl(alkyl)acetamides as Anticancer Agents: Molecular Modeling and Biological Evaluations

AbstractDichloroacetate (DCA) is considered as a highly bioavailable and small anticancer agent which reduces tumor growth through inhibition of pyruvate dehydrogenase kinases. Various DCA derivatives were designed, synthesized and eluated by FT‐IR, 1HNMR, 13CNMR and Mass spectrum. Biological evaluations of the synthesized compounds were evaluated against three human cancer cell lines, A549 (lung), MCF‐7 (breast), and MDA‐MB‐231 (breast), as well as a non‐tumorigenic breast cell line (MCF‐10A). Among synthesized compounds, N‐(2‐(tert‐butylamino)‐1‐(4‐nitrophenyl)‐2‐oxoethyl)‐2,2‐dichloro‐N‐(2‐fluorophenyl)acetamide (A5) had a promising cytotoxic effect with IC50 values of 11.94, 15.57, and 16.54 μM against MCF‐7, MDA‐MB‐231, and A549 cells, respectively. It can also induce apoptosis in MCF‐7 cell line. Molecular docking and molecular dynamic simulation studies were also carried out show binding sites and energies to the PDKs isoenzymes. All of the compounds demonstrated appropriate selectivity between cancerous and non‐cancerous cell lines. These results provide valuable insight for the additional development of novel dichloroacetate‐containing compounds.

Pyruvate dehydrogenase kinase 4 promotes osteoblastic potential of BMP9 by boosting Wnt/β-catenin signaling in mesenchymal stem cells.

Bone morphogenetic protein 9 (BMP9) is an effective osteogenic factor and a promising candidate for bone tissue engineering. The osteoblastic potential of BMP9 needs to be further increased to overcome its shortcomings. However, the details of how BMP9 triggers osteogenic differentiation in mesenchymal stem cells (MSCs) are unclear. In this study, we used real-time PCR, western blot, histochemical staining, mouse ectopic bone formation model, immunofluorescence, immunoprecipitation, and chromatin immunoprecipitation to investigate the role of pyruvate dehydrogenase kinase 4 (PDK4) in BMP9-induced osteogenic differentiation of C3H10T1/2 cells, as well as the underlying mechanism. We found that PDK4 was upregulated by BMP9 in C3H10T1/2 cells. BMP9-induced osteogenic markers and bone mass were increased by PDK4 overexpression, but decreased by PDK4 silencing. β-catenin protein level was increased by BMP9, which was enhanced by PDK overexpression and decreased by PDK4 silencing. BMP9-induced osteogenic markers were reduced by PDK4 silencing, which was almost reversed by β-catenin overexpression. PDK4 increased the BMP9-induced osteogenic markers, which was almost eliminated by β-catenin silencing. Sclerostin was mildly decreased by BMP9 or PDK4, and significantly decreased by combined BMP9 and PDK4. In contrast, sclerostin increased significantly when BMP9 was combined with PDK4 silencing. BMP9-induced p-SMAD1/5/9 was increased by PDK4 overexpression, but was reduced by PDK4 silencing. PDK4 interacts with p-SMAD1/5/9 and regulates the sclerostin promoter. These findings suggest that PDK4 can increase the osteogenic potential of BMP9 by enhancing Wnt/β-catenin signaling via the downregulation of sclerostin. PDK4 may be an effective target to strengthen BMP9-induced osteogenesis.

Role of METTL3 in Aerobic Glycolysis of Glioma by Regulating m6A/miR-27b-3p/PDK1.

Methyltransferase like 3 (METTL3) has been reported to be dysregulated in glioma. However, its role in aerobic glycolysis of glioma remains unknown. This study was conducted to explore the molecular mechanism by which METTL3 regulates aerobic glycolysis of glioma and provide novel targets for the treatment of glioma. The expression levels of METTL3, microRNA (miR)-27b-3p, and pyruvate dehydrogenase kinase 1 (PDK1) were determined in glioma cell lines and normal human astrocytes. Cell proliferation and aerobic glycolysis were evaluated by cell counting kit-8 and colony formation assays and measurements of glucose uptake, lactate production, adenosine triphosphate, Hexokinase activity, oxygen consumption rate, and extracellular acidification rate. After m6A quantification analysis, methylated RNA immunoprecipitation, and the dual-luciferase assay, the rescue experiments were performed using miR-27b-3p inhibitor or pcDNA3.1-PDK1 with pcDNA3.1-METTL3. METTL3 was lower in glioma cells and METTL3 overexpression reduced aerobic glycolysis. METTL3 increased m6A modification to promote the processing of pri-miR-27b by DGCR8 and the expression of mature miR-27b-3p, and miR-27b-3p targeted and inhibited PDK1 expression. miR-27b-3p inhibition or PDK1 overexpression both neutralized the inhibitory role of METTL3 overexpression in aerobic glycolysis. Overall, METTL3 overexpression increased the expression of mature miR-27b-3p via m6A modification and inhibited PDK1 expression, thus suppressing aerobic glycolysis of glioma.