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1.
Sci Rep ; 13(1): 22111, 2023 Dec 13.
Article in English | MEDLINE | ID: mdl-38092801

ABSTRACT

The multilevel current states of synaptic devices in artificial neural networks enable next-generation computing to perform cognitive functions in an energy-efficient manner. Moreover, considering large-scale synaptic arrays, multiple states programmed in a low-current regime may be required to achieve low energy consumption, as demonstrated by simple numerical calculations. Thus, we propose a three-terminal Cu-ion-actuated CuOx/HfOx/WO3 synaptic transistor array that exhibits analogously modulated channel current states in the range of tens of nanoamperes, enabled by WO3 channel engineering. The introduction of an amorphous stoichiometric WO3 channel formed by reactive sputtering with O gas significantly lowered the channel current but left it almost unchanged with respect to consecutive gate voltage pulses. An additional annealing process at 450 °C crystallized the WO3, allowing analog switching in the range of tens of nanoamperes. The incorporation of N gas during annealing induced a highly conductive channel, making the channel current modulation negligible as a function of the gate pulse. Using this optimized gate stack, Poole-Frenkel conduction was identified as a major transport characteristic in a temperature-dependent study. In addition, we found that the channel current modulation is a function of the gate current response, which is related to the degree of progressive movement of the Cu ions. Finally, the synaptic characteristics were updated using fully parallel programming and demonstrated in a 7 × 7 array. Using the CuOx/HfOx/WO3 synaptic transistors as weight elements in multilayer neural networks, we achieved a 90% recognition accuracy on the Fashion-MNIST dataset.

2.
Micromachines (Basel) ; 13(3)2022 Mar 17.
Article in English | MEDLINE | ID: mdl-35334745

ABSTRACT

To enhance the computing efficiency in a neuromorphic architecture, it is important to develop suitable memory devices that can emulate the role of biological synapses. More specifically, not only are multiple conductance states needed to be achieved in the memory but each state is also analogously adjusted by consecutive identical pulses. Recently, electrochemical random-access memory (ECRAM) has been dedicatedly designed to realize the desired synaptic characteristics. Electric-field-driven ion motion through various electrolytes enables the conductance of the ECRAM to be analogously modulated, resulting in a linear and symmetric response. Therefore, the aim of this study is to review recent advances in ECRAM technology from the material and device engineering perspectives. Since controllable mobile ions play an important role in achieving synaptic behavior, the prospect and challenges of ECRAM devices classified according to mobile ion species are discussed.

3.
Cell Death Dis ; 12(3): 250, 2021 03 05.
Article in English | MEDLINE | ID: mdl-33674559

ABSTRACT

Tumors are composed of subpopulations of cancer cells with functionally distinct features. Intratumoral heterogeneity limits the therapeutic effectiveness of cancer drugs. To address this issue, it is important to understand the regulatory mechanisms driving a subclonal variety within a therapy-resistant tumor. We identified tumor subclones of HN9 head and neck cancer cells showing distinct responses to radiation with different levels of p62 expression. Genetically identical grounds but epigenetic heterogeneity of the p62 promoter regions revealed that radioresistant HN9-R clones displayed low p62 expression via the creation of repressive chromatin architecture, in which cooperation between DNMT1 (DNA methyltransferases 1) and HDAC1 (histone deacetylases 1) resulted in DNA methylation and repressive H3K9me3 and H3K27me3 marks in the p62 promoter. Combined inhibition of DNMT1 and HDAC1 by genetic depletion or inhibitors enhanced the suppressive effects on proliferative capacity and in vivo tumorigenesis following irradiation. Importantly, ectopically p62-overexpressed HN9-R clones increased the induction of senescence along with p62-dependent autophagy activation. These results demonstrate the heterogeneous expression of p62 as the key component of clonal variation within a tumor against irradiation. Understanding the epigenetic diversity of p62 heterogeneity among subclones allows for improved identification of the functional state of subclones and provides a novel treatment option to resolve resistance to current therapies.


Subject(s)
Autophagy/drug effects , Cellular Senescence/radiation effects , Epigenesis, Genetic , Head and Neck Neoplasms/radiotherapy , Radiation Tolerance , Sequestosome-1 Protein/metabolism , Squamous Cell Carcinoma of Head and Neck/radiotherapy , Acetylation , Animals , Cell Line, Tumor , Chromatin Assembly and Disassembly , CpG Islands , DNA (Cytosine-5-)-Methyltransferase 1/metabolism , DNA Methylation , Gene Expression Regulation, Neoplastic , Genetic Heterogeneity , Head and Neck Neoplasms/genetics , Head and Neck Neoplasms/metabolism , Head and Neck Neoplasms/pathology , Histone Deacetylase 1/metabolism , Humans , Male , Mice, Nude , Promoter Regions, Genetic , Radiation Tolerance/genetics , Sequestosome-1 Protein/genetics , Signal Transduction , Squamous Cell Carcinoma of Head and Neck/genetics , Squamous Cell Carcinoma of Head and Neck/metabolism , Squamous Cell Carcinoma of Head and Neck/pathology , Xenograft Model Antitumor Assays
4.
Sci Rep ; 10(1): 7620, 2020 05 06.
Article in English | MEDLINE | ID: mdl-32376896

ABSTRACT

Epithelial-mesenchymal transition (EMT) is a major cellular process in which epithelial cells lose cell polarity and cell-cell adhesion and become motility and invasiveness by transforming into mesenchymal cells. Catechol is one of the natural compounds present in fruits and vegetables and has various pharmacological and physiological activities including anti-carcinogenic effects. However, the effects of catechol on EMT has not been reported. Epidermal growth factor (EGF) is one of the growth factors and is known to play a role in inducing EMT. The present study showed that catechol suppressed not only the morphological changes to the mesenchymal phenotype of epithelial HCC cells, but also the reduction of E-cadherin and the increment of Vimentin, which are typical hallmark of EMT. In addition, catechol suppressed EMT-related steps such as migration, invasion, anoikis resistance acquisition, and stem cell-like characterization through the EGFR-AKT-ERK signaling pathway during liver cancer metastasis. Therefore, these results suggest that catechol may be able to regulate the early metastasis of liver cancer in vitro.


Subject(s)
Carcinoma, Hepatocellular/pathology , Catechols/pharmacology , Epidermal Growth Factor/pharmacology , Epithelial-Mesenchymal Transition/drug effects , Liver Neoplasms/pathology , Neoplastic Stem Cells/drug effects , Neoplastic Stem Cells/pathology , Cell Line, Tumor , Cell Movement/drug effects , Cell Proliferation/drug effects , Enzyme Activation/drug effects , ErbB Receptors/metabolism , Gene Expression Regulation, Neoplastic/drug effects , Humans , Matrix Metalloproteinase 2/metabolism , Neoplasm Invasiveness , Proto-Oncogene Proteins c-akt/metabolism , Signal Transduction/drug effects , Snail Family Transcription Factors/metabolism
5.
J Clin Invest ; 129(6): 2431-2445, 2019 05 13.
Article in English | MEDLINE | ID: mdl-31081803

ABSTRACT

How altered metabolism contributes to chemotherapy resistance in cancer cells remains unclear. Through a metabolism-related kinome RNAi screen, we identified inositol-trisphosphate 3-kinase B (ITPKB) as a critical enzyme that contributes to cisplatin-resistant tumor growth. We demonstrated that inositol 1,3,4,5-tetrakisphosphate (IP4), the product of ITPKB, plays a critical role in redox homeostasis upon cisplatin exposure by reducing cisplatin-induced ROS through inhibition of a ROS-generating enzyme, NADPH oxidase 4 (NOX4), which promotes cisplatin-resistant tumor growth. Mechanistically, we identified that IP4 competes with the NOX4 cofactor NADPH for binding and consequently inhibits NOX4. Targeting ITPKB with shRNA or its small-molecule inhibitor resulted in attenuation of NOX4 activity, imbalanced redox status, and sensitized cancer cells to cisplatin treatment in patient-derived xenografts. Our findings provide insight into the crosstalk between kinase-mediated metabolic regulation and platinum-based chemotherapy resistance in human cancers. Our study also suggests a distinctive signaling function of IP4 that regulates NOX4. Furthermore, pharmaceutical inhibition of ITPKB displayed synergistic attenuation of tumor growth with cisplatin, suggesting ITPKB as a promising synthetic lethal target for cancer therapeutic intervention to overcome cisplatin resistance.


Subject(s)
Cisplatin/pharmacology , Drug Resistance, Neoplasm , NADPH Oxidase 4/metabolism , Neoplasm Proteins/metabolism , Neoplasms/enzymology , Phosphotransferases (Alcohol Group Acceptor)/metabolism , Signal Transduction , A549 Cells , Animals , Female , Humans , Mice , Mice, Nude , NADPH Oxidase 4/genetics , Neoplasm Proteins/genetics , Neoplasms/drug therapy , Neoplasms/genetics , Neoplasms/pathology , Oxidation-Reduction/drug effects , Phosphotransferases (Alcohol Group Acceptor)/genetics , Xenograft Model Antitumor Assays
6.
Cancer Cell ; 34(2): 315-330.e7, 2018 08 13.
Article in English | MEDLINE | ID: mdl-30033091

ABSTRACT

Platinum-based chemotherapeutics represent a mainstay of cancer therapy, but resistance limits their curative potential. Through a kinome RNAi screen, we identified microtubule-associated serine/threonine kinase 1 (MAST1) as a main driver of cisplatin resistance in human cancers. Mechanistically, cisplatin but no other DNA-damaging agents inhibit the MAPK pathway by dissociating cRaf from MEK1, while MAST1 replaces cRaf to reactivate the MAPK pathway in a cRaf-independent manner. We show clinical evidence that expression of MAST1, both initial and cisplatin-induced, contributes to platinum resistance and worse clinical outcome. Targeting MAST1 with lestaurtinib, a recently identified MAST1 inhibitor, restores cisplatin sensitivity, leading to the synergistic attenuation of cancer cell proliferation and tumor growth in human cancer cells and patient-derived xenograft models.


Subject(s)
Antineoplastic Agents/pharmacology , Cisplatin/pharmacology , MAP Kinase Kinase 1/physiology , Microtubule-Associated Proteins/physiology , Protein Serine-Threonine Kinases/physiology , Proto-Oncogene Proteins c-raf/physiology , Animals , Cell Line, Tumor , Drug Resistance, Neoplasm , Enzyme Activation , Female , Humans , Mice
7.
J Med Food ; 21(8): 793-800, 2018 Aug.
Article in English | MEDLINE | ID: mdl-30048215

ABSTRACT

Obesity is the most common metabolic disease in developed countries and has become a global epidemic in recent years. Obesity is associated with various metabolic abnormalities, including glucose intolerance, insulin resistance, type 2 diabetes, dyslipidemia, and hypertension. Leaves from the plant Dendropanax morbiferus are beneficial to health as they contain high levels of vitamin C and tannin. There have been seminal studies on the anticancer, antimicrobial, antidiabetes, and antihyperglycemic effects of treatments with D. morbiferus trees. Herein, we investigated the toxicity of D. morbiferus water (DLW) extracts in vitro, and demonstrated no toxicity at 5-500 µg/mL in 24-72-h experiments with 3T3-L1 cells. The DLW increased cell viability at 48 h and inhibited adipogenesis in 3T3-L1 cells by reducing intracellular triglyceride levels and glucose uptake. In addition, mRNA and protein expression levels of adipogenesis-related genes were lowered by DLW, suggesting antiobesity effects in mouse 3T3-L1 cells. Because few studies have demonstrated cholesterol-lowering effects of D. morbiferus, we investigated the activities of adipogenic transcriptional factors following treatments of 3T3-L1 cells with D. morbiferus and observed increased CEBPα, CEBPß, PPARγ, and SREBP1 activities in the cells, indicating that DLW extracts inhibit adipogenesis.


Subject(s)
3T3-L1 Cells/drug effects , Anti-Obesity Agents/pharmacology , Araliaceae , Obesity/drug therapy , Plant Extracts/pharmacology , 3T3-L1 Cells/metabolism , Animals , Anti-Obesity Agents/therapeutic use , Cholesterol/metabolism , Mice , Phytotherapy , Plant Extracts/therapeutic use , Triglycerides/metabolism
8.
BMC Cancer ; 18(1): 605, 2018 May 29.
Article in English | MEDLINE | ID: mdl-29843645

ABSTRACT

BACKGROUND: Aberrant hyperactivation of epithelial proliferation, AKT signaling, and association with unopposed estrogen (E2) exposure is the most common endometrial cancer dysfunction. In the normal uterus, progesterone (P4) inhibits proliferation by coordinating stromal-epithelial cross-talk, which we previously showed is mediated by the function of Mitogen-inducible gene 6 (Mig-6). Despite their attractive characteristics, non-surgical conservative therapies based on progesterone alone have not been universally successful. One barrier to this success has been the lack of understanding of the P4 effect on endometrial cells. METHOD: To further understand the role of Mig-6 and P4 in controlling uterine proliferation, we developed a Sprr2f-cre driven mouse model where Mig-6 is specifically ablated only in the epithelial cells of the uterus (Sprr2f cre+ Mig-6 f/f ). We examined P4 effect and regulation of AKT signaling in the endometrium of mutant mice. RESULTS: Sprr2f cre+ Mig-6 f/f mice developed endometrial hyperplasia. P4 treatment abated the development of endometrial hyperplasia and restored morphological and histological characteristics of the uterus. P4 treatment reduced cell proliferation which was accompanied by decreased AKT signaling and the restoration of stromal PGR and ESR1 expression. Furthermore, our in vitro studies revealed an inhibitory effect of MIG-6 on AKT phosphorylation as well as MIG-6 and AKT protein interactions. CONCLUSIONS: These data suggest that endometrial epithelial cell proliferation is regulated by P4 mediated Mig-6 inhibition of AKT phosphorylation, uncovering new mechanisms of P4 action. This information may help guide more effective non-surgical interventions in the future.


Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Endometrial Neoplasms/pathology , Intracellular Signaling Peptides and Proteins/metabolism , Progesterone/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Tumor Suppressor Proteins/metabolism , Animals , Cell Proliferation , Cornified Envelope Proline-Rich Proteins/genetics , Endometrium/cytology , Endometrium/metabolism , Endometrium/pathology , Epithelial Cells/metabolism , Epithelial Cells/pathology , Estrogen Receptor alpha/metabolism , Female , Humans , Intracellular Signaling Peptides and Proteins/genetics , Mice , Mice, Knockout , Models, Animal , Phosphorylation , Receptors, Progesterone/metabolism , Signal Transduction
9.
Mol Cell ; 69(6): 923-937.e8, 2018 03 15.
Article in English | MEDLINE | ID: mdl-29547721

ABSTRACT

Dietary supplements such as vitamins and minerals are widely used in the hope of improving health but may have unidentified risks and side effects. In particular, a pathogenic link between dietary supplements and specific oncogenes remains unknown. Here we report that chondroitin-4-sulfate (CHSA), a natural glycosaminoglycan approved as a dietary supplement used for osteoarthritis, selectively promotes the tumor growth potential of BRAF V600E-expressing human melanoma cells in patient- and cell line-derived xenograft mice and confers resistance to BRAF inhibitors. Mechanistically, chondroitin sulfate glucuronyltransferase (CSGlcA-T) signals through its product CHSA to enhance casein kinase 2 (CK2)-PTEN binding and consequent phosphorylation and inhibition of PTEN, which requires CHSA chains and is essential to sustain AKT activation in BRAF V600E-expressing melanoma cells. However, this CHSA-dependent PTEN inhibition is dispensable in cancer cells expressing mutant NRAS or PI3KCA, which directly activate the PI3K-AKT pathway. These results suggest that dietary supplements may exhibit oncogene-dependent pro-tumor effects.


Subject(s)
Carcinogens/toxicity , Cell Transformation, Neoplastic/genetics , Chondroitin Sulfates/toxicity , Dietary Supplements/toxicity , Melanoma/chemically induced , Mutation , Proto-Oncogene Proteins B-raf/genetics , Skin Neoplasms/chemically induced , Animals , Antinematodal Agents/pharmacology , Casein Kinase II/metabolism , Cell Proliferation/drug effects , Cell Transformation, Neoplastic/metabolism , Cell Transformation, Neoplastic/pathology , Drug Resistance, Neoplasm/drug effects , Drug Resistance, Neoplasm/genetics , Female , GTP Phosphohydrolases/genetics , HEK293 Cells , HT29 Cells , Humans , Melanoma/drug therapy , Melanoma/enzymology , Melanoma/genetics , Membrane Proteins/genetics , Mice , Mice, Inbred NOD , Mice, Nude , Mice, Transgenic , NIH 3T3 Cells , Nuclear Proteins/genetics , PTEN Phosphohydrolase/antagonists & inhibitors , PTEN Phosphohydrolase/metabolism , Phosphorylation , Protein Kinase Inhibitors/pharmacology , Signal Transduction , Skin Neoplasms/drug therapy , Skin Neoplasms/enzymology , Skin Neoplasms/genetics , Transcription Factors/genetics , Xenograft Model Antitumor Assays
10.
J Med Food ; 20(12): 1152-1159, 2017 Dec.
Article in English | MEDLINE | ID: mdl-29243967

ABSTRACT

Porphyra tenera, also known as nori, is a red algal species of seaweed. It is cultivated in Asia for culinary purposes. We report that P. tenera extract (PTE) enhances the immune response in mouse macrophages. We found that P. tenera extract regulates the NF-κB IκB kinase (IKK) signaling pathway, and we assessed the expression and translocation of p65, a subunit of NF-κB, in RAW264.7 mouse macrophage cells after treatment with PTE. We also investigated the effects of 10% ethanol PTE (PTE10) in RAW264.7 cells. The production of IL-10, IL-6, TNF-α, and IFN-γ was induced by PTE treatment of the macrophages, and PTE also enhanced p-IκB and p-AKT. PTE10 showed no cytotoxicity at 10-20 µg/mL in RAW264.7 cells. PTE10, in fact, increased cell viability at 24 h, stimulated macrophage cells, and induced the phosphorylation of Akt. Akt stimulates IKK activity through the phosphorylation of IKKα and enhances immune activity through the activation of NF-κB. In this study, NF-κB activation was induced by increasing p-NF-κB and p-IKK. A subunit of NF-κB, p65, was located in the nucleus and increased the expression of various cytokines. PTE thus enhanced the immune response through IκB-α immunostimulation signaling in RAW264.7 cells. PTE10 has potential therefore for development of future treatments requiring immune system stimulation.


Subject(s)
Macrophages/drug effects , Macrophages/immunology , NF-kappa B/immunology , Plant Extracts/pharmacology , Porphyra/chemistry , Seaweed/chemistry , Animals , I-kappa B Kinase/genetics , I-kappa B Kinase/immunology , Interleukin-10/genetics , Interleukin-10/immunology , Interleukin-6/genetics , Interleukin-6/immunology , Mice , NF-kappa B/genetics , Phosphorylation , Proto-Oncogene Proteins c-akt/genetics , Proto-Oncogene Proteins c-akt/immunology , Signal Transduction/drug effects
11.
J Biol Chem ; 292(24): 10142-10152, 2017 06 16.
Article in English | MEDLINE | ID: mdl-28468827

ABSTRACT

Contributions of metabolic changes to cancer development and maintenance have received increasing attention in recent years. Although many human cancers share similar metabolic alterations, it remains unclear whether oncogene-specific metabolic alterations are required for tumor development. Using an RNAi-based screen targeting the majority of the known metabolic proteins, we recently found that oncogenic BRAFV600E up-regulates HMG-CoA lyase (HMGCL), which converts HMG-CoA to acetyl-CoA and a ketone body, acetoacetate, that selectively enhances BRAFV600E-dependent MEK1 activation in human cancer. Here, we identified HMG-CoA synthase 1 (HMGCS1), the upstream ketogenic enzyme of HMGCL, as an additional "synthetic lethal" partner of BRAFV600E Although HMGCS1 expression did not correlate with BRAFV600E mutation in human melanoma cells, HMGCS1 was selectively important for proliferation of BRAFV600E-positive melanoma and colon cancer cells but not control cells harboring active N/KRAS mutants, and stable knockdown of HMGCS1 only attenuated colony formation and tumor growth potential of BRAFV600E melanoma cells. Moreover, cytosolic HMGCS1 that co-localized with HMGCL and BRAFV600E was more important than the mitochondrial HMGCS2 isoform in BRAFV600E-expressing cancer cells in terms of acetoacetate production. Interestingly, HMGCL knockdown did not affect HMGCS1 expression levels, whereas HMGCS1 knockdown caused a compensating increase in HMGCL protein level because of attenuated protein degradation. However, this increase did not reverse the reduced ketogenesis in HMGCS1 knockdown cells. Mechanistically, HMGCS1 inhibition decreased intracellular acetoacetate levels, leading to reduced BRAFV600E-MEK1 binding and consequent MEK1 activation. We conclude that the ketogenic HMGCS1-HMGCL-acetoacetate axis may represent a promising therapeutic target for managing BRAFV600E-positive human cancers.


Subject(s)
Colonic Neoplasms/enzymology , Hydroxymethylglutaryl-CoA Synthase/metabolism , MAP Kinase Kinase 1/metabolism , Melanoma/enzymology , Neoplasm Proteins/metabolism , Oxo-Acid-Lyases/metabolism , Proto-Oncogene Proteins B-raf/metabolism , Acetoacetates/metabolism , Amino Acid Substitution , Animals , Cell Line, Tumor , Cell Proliferation , Colonic Neoplasms/metabolism , Colonic Neoplasms/pathology , Cytosol/enzymology , Cytosol/metabolism , Enzyme Activation , Enzyme Stability , Female , Humans , Hydroxymethylglutaryl-CoA Synthase/antagonists & inhibitors , Hydroxymethylglutaryl-CoA Synthase/genetics , Isoenzymes/antagonists & inhibitors , Isoenzymes/genetics , Isoenzymes/metabolism , MAP Kinase Kinase 1/chemistry , Melanoma/metabolism , Melanoma/pathology , Mice, Nude , Mutation , Neoplasm Proteins/antagonists & inhibitors , Neoplasm Proteins/chemistry , Neoplasm Proteins/genetics , Neoplasm Transplantation , Oxo-Acid-Lyases/antagonists & inhibitors , Oxo-Acid-Lyases/chemistry , Oxo-Acid-Lyases/genetics , Proteolysis , Proto-Oncogene Proteins B-raf/genetics , RNA Interference , Tumor Burden
12.
Cell Metab ; 25(2): 358-373, 2017 02 07.
Article in English | MEDLINE | ID: mdl-28089569

ABSTRACT

Lifestyle factors, including diet, play an important role in the survival of cancer patients. However, the molecular mechanisms underlying pathogenic links between diet and particular oncogenic mutations in human cancers remain unclear. We recently reported that the ketone body acetoacetate selectively enhances BRAF V600E mutant-dependent MEK1 activation in human cancers. Here we show that a high-fat ketogenic diet increased serum levels of acetoacetate, leading to enhanced tumor growth potential of BRAF V600E-expressing human melanoma cells in xenograft mice. Treatment with hypolipidemic agents to lower circulating acetoacetate levels or an inhibitory homolog of acetoacetate, dehydroacetic acid, to antagonize acetoacetate-BRAF V600E binding attenuated BRAF V600E tumor growth. These findings reveal a signaling basis underlying a pathogenic role of dietary fat in BRAF V600E-expressing melanoma, providing insights into the design of conceptualized "precision diets" that may prevent or delay tumor progression based on an individual's specific oncogenic mutation profile.


Subject(s)
Dietary Fats/adverse effects , Ketone Bodies/metabolism , Melanoma/pathology , Mutation/genetics , Proto-Oncogene Proteins B-raf/genetics , 3-Hydroxybutyric Acid/pharmacology , Acetoacetates/administration & dosage , Acetoacetates/blood , Acetoacetates/pharmacology , Animals , Cell Proliferation/drug effects , Female , Humans , Hypolipidemic Agents/pharmacology , Injections, Intraperitoneal , Melanoma/blood , Mice , Mice, Nude , Pyrones/chemistry , Pyrones/pharmacology , Xenograft Model Antitumor Assays
13.
Int J Biochem Cell Biol ; 81(Pt A): 76-81, 2016 12.
Article in English | MEDLINE | ID: mdl-27793752

ABSTRACT

Cancer cells are characterized by altered metabolic processes. Recent evidence of metabolic alterations has indicated that the fatty acid oxidation (FAO) pathway is used as a carbon source for anabolic processes in some tumors, thus making this pathway a potential target for therapy. The carnitine palmitoyltransferase (CPT; EC 2.3.1.21) enzyme transfers long-chain fatty acids from the cytosol to the mitochondrial matrix for ß-oxidation. Because carnitine palmitoyl transferase 1a (CPT1a) is the rate-limiting enzyme for FAO, the authors evaluated the effects of CPT1A knock-down in BRAF V600E melanoma cell lines. The results showed that knock-down of CPT1A inhibited FAO and that CPT1A is critical for malignant V600E melanoma cells, particularly BRAF V600E melanoma cells. The proliferation and tumorigenesis in V600E melanoma were decrease after CPT1A knockdown. These results suggest that therapy for BRAF V600E melanoma can include targeting metabolic alterations. CPT1A is more important for lipid synthesis in V600E mutant melanoma cells than in wild-type BRAF melanoma cells.


Subject(s)
Carnitine O-Palmitoyltransferase/metabolism , Melanoma/metabolism , Melanoma/pathology , Molecular Targeted Therapy , Mutation , Proto-Oncogene Proteins B-raf/genetics , Animals , Carcinogenesis/drug effects , Carnitine O-Palmitoyltransferase/deficiency , Carnitine O-Palmitoyltransferase/genetics , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Transformation, Neoplastic , Female , Gene Knockdown Techniques , Humans , Melanoma/drug therapy , Melanoma/genetics , Mice , Oxidation-Reduction/drug effects
14.
Nat Chem ; 7(12): 968-79, 2015 Dec.
Article in English | MEDLINE | ID: mdl-26587712

ABSTRACT

Copper is a transition metal that plays critical roles in many life processes. Controlling the cellular concentration and trafficking of copper offers a route to disrupt these processes. Here we report small molecules that inhibit the human copper-trafficking proteins Atox1 and CCS, and so provide a selective approach to disrupt cellular copper transport. The knockdown of Atox1 and CCS or their inhibition leads to a significantly reduced proliferation of cancer cells, but not of normal cells, as well as to attenuated tumour growth in mouse models. We show that blocking copper trafficking induces cellular oxidative stress and reduces levels of cellular ATP. The reduced level of ATP results in activation of the AMP-activated protein kinase that leads to reduced lipogenesis. Both effects contribute to the inhibition of cancer cell proliferation. Our results establish copper chaperones as new targets for future developments in anticancer therapies.


Subject(s)
Cell Proliferation/drug effects , Copper/metabolism , Metallochaperones/antagonists & inhibitors , Molecular Chaperones/antagonists & inhibitors , Neoplasms/metabolism , Amino Acid Sequence , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Copper Transport Proteins , Drug Discovery , Gene Knockdown Techniques , Humans , Metallochaperones/chemistry , Metallochaperones/genetics , Metallochaperones/metabolism , Mice , Molecular Chaperones/chemistry , Molecular Chaperones/genetics , Molecular Chaperones/metabolism , Molecular Sequence Data , Oxidative Stress/drug effects , Sequence Alignment , Xenograft Model Antitumor Assays
15.
Nat Cell Biol ; 17(11): 1484-96, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26479318

ABSTRACT

The oxidative pentose phosphate pathway (PPP) contributes to tumour growth, but the precise contribution of 6-phosphogluconate dehydrogenase (6PGD), the third enzyme in this pathway, to tumorigenesis remains unclear. We found that suppression of 6PGD decreased lipogenesis and RNA biosynthesis and elevated ROS levels in cancer cells, attenuating cell proliferation and tumour growth. 6PGD-mediated production of ribulose-5-phosphate (Ru-5-P) inhibits AMPK activation by disrupting the active LKB1 complex, thereby activating acetyl-CoA carboxylase 1 and lipogenesis. Ru-5-P and NADPH are thought to be precursors in RNA biosynthesis and lipogenesis, respectively; thus, our findings provide an additional link between the oxidative PPP and lipogenesis through Ru-5-P-dependent inhibition of LKB1-AMPK signalling. Moreover, we identified and developed 6PGD inhibitors, physcion and its derivative S3, that effectively inhibited 6PGD, cancer cell proliferation and tumour growth in nude mice xenografts without obvious toxicity, suggesting that 6PGD could be an anticancer target.


Subject(s)
AMP-Activated Protein Kinases/metabolism , Lipogenesis , Neoplasms/metabolism , Pentose Phosphate Pathway , Phosphogluconate Dehydrogenase/metabolism , Protein Serine-Threonine Kinases/metabolism , AMP-Activated Protein Kinase Kinases , Humans , Neoplasms/pathology , Oxidative Stress , Ribulosephosphates/metabolism , Signal Transduction
16.
Mol Cell ; 59(3): 345-358, 2015 Aug 06.
Article in English | MEDLINE | ID: mdl-26145173

ABSTRACT

Many human cancers share similar metabolic alterations, including the Warburg effect. However, it remains unclear whether oncogene-specific metabolic alterations are required for tumor development. Here we demonstrate a "synthetic lethal" interaction between oncogenic BRAF V600E and a ketogenic enzyme 3-hydroxy-3-methylglutaryl-CoA lyase (HMGCL). HMGCL expression is upregulated in BRAF V600E-expressing human primary melanoma and hairy cell leukemia cells. Suppression of HMGCL specifically attenuates proliferation and tumor growth potential of human melanoma cells expressing BRAF V600E. Mechanistically, active BRAF upregulates HMGCL through an octamer transcription factor Oct-1, leading to increased intracellular levels of HMGCL product, acetoacetate, which selectively enhances binding of BRAF V600E but not BRAF wild-type to MEK1 in V600E-positive cancer cells to promote activation of MEK-ERK signaling. These findings reveal a mutation-specific mechanism by which oncogenic BRAF V600E "rewires" metabolic and cell signaling networks and signals through the Oct-1-HMGCL-acetoacetate axis to selectively promote BRAF V600E-dependent tumor development.


Subject(s)
Leukemia, Hairy Cell/metabolism , MAP Kinase Kinase 1/metabolism , Melanoma/metabolism , Octamer Transcription Factor-1/metabolism , Oxo-Acid-Lyases/metabolism , Proto-Oncogene Proteins B-raf/metabolism , Signal Transduction , Acetoacetates/metabolism , Cell Line, Tumor , Gene Expression Regulation, Neoplastic , Humans , Mutation , Proto-Oncogene Proteins B-raf/genetics , Up-Regulation
17.
Cancer Cell ; 27(2): 257-70, 2015 Feb 09.
Article in English | MEDLINE | ID: mdl-25670081

ABSTRACT

How mitochondrial glutaminolysis contributes to redox homeostasis in cancer cells remains unclear. Here we report that the mitochondrial enzyme glutamate dehydrogenase 1 (GDH1) is commonly upregulated in human cancers. GDH1 is important for redox homeostasis in cancer cells by controlling the intracellular levels of its product alpha-ketoglutarate and subsequent metabolite fumarate. Mechanistically, fumarate binds to and activates a reactive oxygen species scavenging enzyme glutathione peroxidase 1. Targeting GDH1 by shRNA or a small molecule inhibitor R162 resulted in imbalanced redox homeostasis, leading to attenuated cancer cell proliferation and tumor growth.


Subject(s)
Glutamate Dehydrogenase/biosynthesis , Glutathione Peroxidase/biosynthesis , Glutathione/metabolism , Leukemia/genetics , Mitochondria/enzymology , Antioxidants/metabolism , Carcinogenesis , Fumarates/metabolism , Gene Expression Regulation, Neoplastic , Glutamate Dehydrogenase/antagonists & inhibitors , Glutamate Dehydrogenase/genetics , Glutathione Peroxidase/genetics , Humans , Ketoglutaric Acids/metabolism , Leukemia/enzymology , Leukemia/pathology , Mitochondria/pathology , Oxidation-Reduction , Primary Cell Culture , Reactive Oxygen Species/metabolism , Signal Transduction/genetics , Glutathione Peroxidase GPX1
18.
Hum Mol Genet ; 24(4): 1127-41, 2015 Feb 15.
Article in English | MEDLINE | ID: mdl-25305081

ABSTRACT

Deciphering the molecular basis of neuronal cell death is a central issue in the etiology of neurodegenerative diseases, such as Parkinson's and Alzheimer's. Dysregulation of p53 levels has been implicated in neuronal apoptosis. The role of histone deacetylase 3 (HDAC3) in suppressing p53-dependent apoptosis has been recently emphasized; however, the molecular basis of modulation of p53 function by HDAC3 remains unclear. Here we show that PTEN-induced putative kinase 1 (PINK1), which is linked to autosomal recessive early-onset familial Parkinson's disease, phosphorylates HDAC3 at Ser-424 to enhance its HDAC activity in a neural cell-specific manner. PINK1 prevents H2O2-induced C-terminal cleavage of HDAC3 via phosphorylation of HDAC3 at Ser-424, which is reversed by protein phosphatase 4c. PINK1-mediated phosphorylation of HDAC3 enhances its direct association with p53 and causes subsequent hypoacetylation of p53. Genetic deletion of PINK1 partly impaired the suppressive role of HDAC3 in regulating p53 acetylation and transcriptional activity. However, depletion of HDAC3 fully abolished the PINK1-mediated p53 inhibitory loop. Finally, ectopic expression of phosphomometic-HDAC3(S424E) substantially overcomes the defective action of PINK1 against oxidative stress in dopaminergic neuronal cells. Together, our results uncovered a mechanism by which PINK1-HDAC3 network mediates p53 inhibitory loop in response to oxidative stress-induced damage.


Subject(s)
Dopaminergic Neurons/metabolism , Histone Deacetylases/metabolism , Protein Kinases/metabolism , Acetylation/drug effects , Animals , Caspase 7/metabolism , Cell Death/genetics , Cell Line , Cytoplasm/metabolism , Dopaminergic Neurons/pathology , Enzyme Activation , Histone Deacetylases/genetics , Humans , Hydrogen Peroxide/pharmacology , Mice , Organ Specificity , Phosphorylation , Protein Kinases/genetics , Proteolysis , Tumor Suppressor Protein p53/metabolism
19.
J Biol Chem ; 289(38): 26533-26541, 2014 Sep 19.
Article in English | MEDLINE | ID: mdl-25104357

ABSTRACT

The mitochondrial pyruvate dehydrogenase complex (PDC) plays a crucial role in regulation of glucose homoeostasis in mammalian cells. PDC flux depends on catalytic activity of the most important enzyme component pyruvate dehydrogenase (PDH). PDH kinase inactivates PDC by phosphorylating PDH at specific serine residues, including Ser-293, whereas dephosphorylation of PDH by PDH phosphatase restores PDC activity. The current understanding suggests that Ser-293 phosphorylation of PDH impedes active site accessibility to its substrate pyruvate. Here, we report that phosphorylation of a tyrosine residue Tyr-301 also inhibits PDH α 1 (PDHA1) by blocking pyruvate binding through a novel mechanism in addition to Ser-293 phosphorylation. In addition, we found that multiple oncogenic tyrosine kinases directly phosphorylate PDHA1 at Tyr-301, and Tyr-301 phosphorylation of PDHA1 is common in EGF-stimulated cells as well as diverse human cancer cells and primary leukemia cells from human patients. Moreover, expression of a phosphorylation-deficient PDHA1 Y301F mutant in cancer cells resulted in increased oxidative phosphorylation, decreased cell proliferation under hypoxia, and reduced tumor growth in mice. Together, our findings suggest that phosphorylation at distinct serine and tyrosine residues inhibits PDHA1 through distinct mechanisms to impact active site accessibility, which act in concert to regulate PDC activity and promote the Warburg effect.


Subject(s)
Protein Processing, Post-Translational , Pyruvate Dehydrogenase (Lipoamide)/metabolism , 3T3 Cells , Amino Acid Substitution , Animals , Carbohydrate Metabolism , Catalytic Domain , Cell Hypoxia , Cell Line, Tumor , Cell Proliferation , Epidermal Growth Factor/physiology , Humans , Mice , Mice, Nude , Neoplasm Transplantation , Oxidative Phosphorylation , Phosphorylation , Protein Binding , Pyruvate Dehydrogenase (Lipoamide)/chemistry , Pyruvate Dehydrogenase (Lipoamide)/genetics , Pyruvic Acid/chemistry , Receptor, Fibroblast Growth Factor, Type 1/metabolism , Tumor Burden , Tyrosine/metabolism
20.
Mol Cell ; 55(4): 552-65, 2014 Aug 21.
Article in English | MEDLINE | ID: mdl-25042803

ABSTRACT

Although the oxidative pentose phosphate pathway is important for tumor growth, how 6-phosphogluconate dehydrogenase (6PGD) in this pathway is upregulated in human cancers is unknown. We found that 6PGD is commonly activated in EGF-stimulated cells and human cancer cells by lysine acetylation. Acetylation at K76 and K294 of 6PGD promotes NADP(+) binding to 6PGD and formation of active 6PGD dimers, respectively. Moreover, we identified DLAT and ACAT2 as upstream acetyltransferases of K76 and K294, respectively, and HDAC4 as the deacetylase of both sites. Expressing acetyl-deficient mutants of 6PGD in cancer cells significantly attenuated cell proliferation and tumor growth. This is due in part to reduced levels of 6PGD products ribulose-5-phosphate and NADPH, which led to reduced RNA and lipid biosynthesis as well as elevated ROS. Furthermore, 6PGD activity is upregulated with increased lysine acetylation in primary leukemia cells from human patients, providing mechanistic insights into 6PGD upregulation in cancer cells.


Subject(s)
Acetyl-CoA C-Acetyltransferase/metabolism , Dihydrolipoyllysine-Residue Acetyltransferase/metabolism , Histone Deacetylases/metabolism , Leukemia/pathology , Lung Neoplasms/pathology , Lysine/metabolism , Phosphogluconate Dehydrogenase/metabolism , Acetylation , Animals , Cell Line, Tumor , Gene Expression Regulation, Neoplastic , Humans , Leukemia/metabolism , Lung Neoplasms/metabolism , Mice , NADP/metabolism , Neoplasms, Experimental , Protein Binding/physiology , Protein Multimerization
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