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Caduff A, Ben Ishai P, Feldman Y. Continuous noninvasive glucose monitoring; water as a relevant marker of glucose uptake in vivo. Biophys Rev 2019; 11:1017-1035. [PMID: 31741172 DOI: 10.1007/s12551-019-00601-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 10/13/2019] [Indexed: 01/22/2023] Open
Abstract
With diabetes set to become the number 3 killer in the Western hemisphere and proportionally growing in other parts of the world, the subject of noninvasive monitoring of glucose dynamics in blood remains a "hot" topic, with the involvement of many groups worldwide. There is a plethora of techniques involved in this academic push, but the so-called multisensor system with an impedance-based core seems to feature increasingly strongly. However, the symmetrical structure of the glucose molecule and its shielding by the smaller dipoles of water would suggest that this option should be less enticing. Yet there is enough phenomenological evidence to suggest that impedance-based methods are truly sensitive to the biophysical effects of glucose variations in the blood. We have been trying to answer this very fundamental conundrum: "Why is impedance or dielectric spectroscopy sensitive to glucose concentration changes in the blood and why can this be done over a very broad frequency band, including microwaves?" The vistas for medical diagnostics are very enticing. There have been a significant number of papers published that look seriously at this problem. In this review, we want to summarize this body of research and the underlying mechanisms and propose a perspective toward utilizing the phenomena. It is our impression that the current world view on the dielectric response of glucose in solution, as outlined below, will support the further evolution and implementation toward practical noninvasive glucose monitoring solutions.
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Affiliation(s)
- Andreas Caduff
- Applied Physics Department and the Center for Electromagnetic Research and Characterization, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel
| | - Paul Ben Ishai
- Department of Physics, Ariel University, 40700, Ariel, Israel
| | - Yuri Feldman
- Applied Physics Department and the Center for Electromagnetic Research and Characterization, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel.
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Targeting MYC Dependence by Metabolic Inhibitors in Cancer. Genes (Basel) 2017; 8:genes8040114. [PMID: 28362357 PMCID: PMC5406861 DOI: 10.3390/genes8040114] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 03/23/2017] [Accepted: 03/27/2017] [Indexed: 12/11/2022] Open
Abstract
MYC is a critical growth regulatory gene that is commonly overexpressed in a wide range of cancers. Therapeutic targeting of MYC transcriptional activity has long been a goal, but it has been difficult to achieve with drugs that directly block its DNA-binding ability. Additional approaches that exploit oncogene addiction are promising strategies against MYC-driven cancers. Also, drugs that target metabolic regulatory pathways and enzymes have potential for indirectly reducing MYC levels. Glucose metabolism and oxidative phosphorylation, which can be targeted by multiple agents, promote cell growth and MYC expression. Likewise, modulation of the signaling pathways and protein synthesis regulated by adenosine monophosphate-activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) can also be an effective route for suppressing MYC translation. Furthermore, recent data suggest that metabolism of nucleotides, fatty acids and glutamine are exploited to alter MYC levels. Combination therapies offer potential new approaches to overcome metabolic plasticity caused by single agents. Although potential toxicities must be carefully controlled, new inhibitors currently being tested in clinical trials offer significant promise. Therefore, as both a downstream target of metabolism and an upstream regulator, MYC is a prominent central regulator of cancer metabolism. Exploiting metabolic vulnerabilities of MYC-driven cancers is an emerging research area with translational potential.
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Sabnis HS, Bradley HL, Tripathi S, Yu WM, Tse W, Qu CK, Bunting KD. Synergistic cell death in FLT3-ITD positive acute myeloid leukemia by combined treatment with metformin and 6-benzylthioinosine. Leuk Res 2016; 50:132-140. [PMID: 27760406 DOI: 10.1016/j.leukres.2016.10.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 08/23/2016] [Accepted: 10/04/2016] [Indexed: 02/08/2023]
Abstract
Current therapy for acute myeloid leukemia (AML) primarily includes high-dose cytotoxic chemotherapy with or without allogeneic stem cell transplantation. Targeting unique cellular metabolism of cancer cells is a potentially less toxic approach. Monotherapy with mitochondrial inhibitors like metformin have met with limited success since escape mechanisms such as increased glycolytic ATP production, especially in hyperglycemia, can overcome the metabolic blockade. As an alternative strategy for metformin therapy, we hypothesized that the combination of 6-benzylthioinosine (6-BT), a broad-spectrum metabolic inhibitor, and metformin could block this drug resistance mechanism. Metformin treatment alone resulted in significant suppression of ROS and mitochondrial respiration with increased glycolysis accompanied by modest cytotoxicity (10-25%). In contrast, 6-BT monotherapy resulted in inhibition of glucose uptake, decreased glycolysis, and decreased ATP with minimal changes in ROS and mitochondrial respiration. The combination of 6-BT with metformin resulted in significant cytotoxicity (60-70%) in monocytic AML cell lines and was associated with inhibition of FLT3-ITD activated STAT5 and reduced c-Myc and GLUT-1 expression. Therefore, although the anti-tumor and metabolic effects of metformin have been limited by the metabolic reprogramming within cells, the novel combination of 6-BT and metformin targets this bypass mechanism resulting in reduced glycolysis, STAT5 inhibition, and increased cell death.
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Affiliation(s)
- Himalee S Sabnis
- Department of Pediatrics, Division of Hem/Onc/BMT, Emory University, Atlanta, GA, USA; Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Atlanta, GA, USA
| | - Heath L Bradley
- Department of Pediatrics, Division of Hem/Onc/BMT, Emory University, Atlanta, GA, USA; Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Atlanta, GA, USA
| | - Shweta Tripathi
- Department of Pediatrics, Division of Hem/Onc/BMT, Emory University, Atlanta, GA, USA; Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Atlanta, GA, USA
| | - Wen-Mei Yu
- Department of Pediatrics, Division of Hem/Onc/BMT, Emory University, Atlanta, GA, USA; Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Atlanta, GA, USA
| | - William Tse
- Department of Medicine, Division of Bone Marrow Transplantation, University of Louisville, Louisville, KY, USA, USA
| | - Cheng-Kui Qu
- Department of Pediatrics, Division of Hem/Onc/BMT, Emory University, Atlanta, GA, USA; Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Atlanta, GA, USA
| | - Kevin D Bunting
- Department of Pediatrics, Division of Hem/Onc/BMT, Emory University, Atlanta, GA, USA; Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Atlanta, GA, USA.
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Vilas GL, Loganathan SK, Quon A, Sundaresan P, Vithana EN, Casey J. Oligomerization of SLC4A11 protein and the severity of FECD and CHED2 corneal dystrophies caused by SLC4A11 mutations. Hum Mutat 2011; 33:419-28. [PMID: 22072594 DOI: 10.1002/humu.21655] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 10/31/2011] [Indexed: 11/06/2022]
Abstract
Mutations in the SLC4A11 gene, which encodes a plasma membrane borate transporter, cause recessive congenital hereditary endothelial corneal dystrophy type 2 (CHED2), corneal dystrophy and perceptive deafness (Harboyan syndrome), and dominant late-onset Fuchs endothelial corneal dystrophy (FECD). We analyzed missense SLC4A11 mutations identified in FECD and CHED2 patients and expressed in transfected HEK 293 cells. Chemical cross-linking and migration in nondenaturing gels showed that SLC4A11 exists as a dimer. Furthermore, co-immunoprecipitation of epitope-tagged proteins revealed heteromeric interactions between wild-type (WT) and mutant SLC4A11 proteins. When expressed alone, FECD- and CHED2-causing mutant SLC4A11 proteins are primarily retained intracellularly. Co-expression with WT SLC4A11 partially rescued the cell surface trafficking of CHED2 mutants, but not FECD mutants. CHED2 alleles of SLC4A11 did not affect cell surface processing of WT SLC4A11. In contrast, FECD mutants reduced WT cell surface processing efficiency, consistent with dominant inheritance of FECD. The reduction in movement of WT protein to the cell surface caused by FECD SLC4A11 helps to explain the dominant inheritance of this disorder. Similarly, the failure of CHED2 mutant SLC4A11 to affect the processing of WT protein, explains the lack of symptoms found in CHED2 carriers and the recessive inheritance of the disorder.
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Affiliation(s)
- Gonzalo L Vilas
- Membrane Protein Disease Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, Canada
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Livshits L, Caduff A, Talary MS, Lutz HU, Hayashi Y, Puzenko A, Shendrik A, Feldman Y. The role of GLUT1 in the sugar-induced dielectric response of human erythrocytes. J Phys Chem B 2009; 113:2212-20. [PMID: 19166280 DOI: 10.1021/jp808721w] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We propose a key role for the glucose transporter 1 (GLUT1) in mediating the observed changes in the dielectric properties of human erythrocyte membranes as determined by dielectric spectroscopy. Cytochalasin B, a GLUT1 transport inhibitor, abolished the membrane capacitance changes in glucose-exposed red cells. Surprisingly, D-fructose, known to be transported primarily by GLUT5, exerted similar membrane capacitance changes at increasing D-fructose concentrations. In order to evaluate whether the glucose-mediated membrane capacitance changes originated directly from intracellularly bound adenosine triphosphate (ATP) or other components of the glycolysis process, we studied the dielectric responses of swollen erythrocytes with a decreased ATP content and of nucleotide-filled ghosts. Resealed ghosts containing physiological concentrations of ATP yielded the same glucose-dependent capacitance changes as biconcave intact red blood cells, further supporting the finding that ATP is the effector of the glucose-mediated dielectric response where the ATP concentration is also the mediating factor in swollen red blood cells. The results suggest that ATP binding to GLUT1 elicits a membrane capacitance change that increases with the applied concentration gradient of D-glucose. A simplified model of the membrane capacitance alteration with glucose uptake is proposed.
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Affiliation(s)
- Leonid Livshits
- Department of Applied Physics, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
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Ye H. Simultaneous determination of protein aggregation, degradation, and absolute molecular weight by size exclusion chromatography–multiangle laser light scattering. Anal Biochem 2006; 356:76-85. [PMID: 16839514 DOI: 10.1016/j.ab.2006.05.025] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Revised: 05/12/2006] [Accepted: 05/17/2006] [Indexed: 10/24/2022]
Abstract
The feasibility of size exclusion chromotography (SEC)-multiangle laser-light scattering as a technique to investigate aggregation and degradation of glycosylated and nonglycosylated proteins, and antibodies under various conditions such as addition of detergent, changes in pH, and variation of protein concentration and heat stress temperature was examined. Separation of proteins and their aggregates was performed using SEC-high-performance liquid chromatography. Detection of analytes was carried out with on-line UV, refractive index, and multiangle laser light-scattering detectors. Quantification and molecular weight determination were performed using commercial software. Aggregation and degradation were examined under various conditions and quantitative results are presented for bovine serum albumin, choriogonadotropin, glyceraldehyde-3-phosphate dehydrogenase, Herceptin, and ReoPro. This method can simultaneously determine both the quantities and the molecular weights of macromolecules from a single injection. The determination of molecular weight is absolute which avoids misleading results caused by molecular shape or interactions with the column matrix. This technique is valuable not only for assessing the extent of aggregation but also for effectively monitoring molecule degradation as evidenced by molecular weight reduction and change in monomer amount.
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Affiliation(s)
- Hongping Ye
- Division of Pharmaceutical Analysis, Food and Drug Administration, 1114 Market Street, Room 1002, St. Louis, MO 63101, USA.
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Buzón V, Padrós E, Cladera J. Interaction of Fusion Peptides from HIV gp41 with Membranes: A Time-Resolved Membrane Binding, Lipid Mixing, and Structural Study. Biochemistry 2005; 44:13354-64. [PMID: 16201760 DOI: 10.1021/bi050382r] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The interaction of the so-called fusion peptide of the human immunodeficiency virus gp41 envelope glycoprotein with the target cell membrane is believed to trigger the fusion process which allows the entry of the virus into the cell. Many studies on the interaction of the fusion peptide with biological membranes have been carried out using synthetic peptides and model membranes. Due to the variety of experimental systems and sequences used, some controversy exists, concerning mainly the type of structure which triggers membrane destabilization and fusion (alpha helix or beta structure). With the aim of contributing to shed some light on the subject we have undertaken a series of experiments on the interaction of the three most representative fusion sequences with model membranes under the same experimental conditions. The results show that the fusion peptides, which adopt an unordered structure when dissolved in DMSO, form a mixture of aggregated beta and helical + unordered structures in aqueous buffer. Model membranes are shown to enhance the formation of aggregated beta structures. The nature of the membrane binding event, the kinetics of the binding and lipid mixing processes, and the kinetics of the structural changes depend on whether both ends of the fusion sequence or just one bears a positive charge. Analysis of the kinetic data shows that lipid mixing depends on the transformation of unordered + helical structures into aggregated beta structures upon binding to the membrane.
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Affiliation(s)
- Víctor Buzón
- Unitat de Biofísica, Departament de Bioquímica i de Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
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