1
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Boltman T, Meyer M, Ekpo O. Diagnostic and Therapeutic Approaches for Glioblastoma and Neuroblastoma Cancers Using Chlorotoxin Nanoparticles. Cancers (Basel) 2023; 15:3388. [PMID: 37444498 DOI: 10.3390/cancers15133388] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 05/04/2023] [Accepted: 05/06/2023] [Indexed: 07/15/2023] Open
Abstract
Glioblastoma multiforme (GB) and high-risk neuroblastoma (NB) are known to have poor therapeutic outcomes. As for most cancers, chemotherapy and radiotherapy are the current mainstay treatments for GB and NB. However, the known limitations of systemic toxicity, drug resistance, poor targeted delivery, and inability to access the blood-brain barrier (BBB), make these treatments less satisfactory. Other treatment options have been investigated in many studies in the literature, especially nutraceutical and naturopathic products, most of which have also been reported to be poorly effective against these cancer types. This necessitates the development of treatment strategies with the potential to cross the BBB and specifically target cancer cells. Compounds that target the endopeptidase, matrix metalloproteinase 2 (MMP-2), have been reported to offer therapeutic insights for GB and NB since MMP-2 is known to be over-expressed in these cancers and plays significant roles in such physiological processes as angiogenesis, metastasis, and cellular invasion. Chlorotoxin (CTX) is a promising 36-amino acid peptide isolated from the venom of the deathstalker scorpion, Leiurus quinquestriatus, demonstrating high selectivity and binding affinity to a broad-spectrum of cancers, especially GB and NB through specific molecular targets, including MMP-2. The favorable characteristics of nanoparticles (NPs) such as their small sizes, large surface area for active targeting, BBB permeability, etc. make CTX-functionalized NPs (CTX-NPs) promising diagnostic and therapeutic applications for addressing the many challenges associated with these cancers. CTX-NPs may function by improving diffusion through the BBB, enabling increased localization of chemotherapeutic and genotherapeutic drugs to diseased cells specifically, enhancing imaging modalities such as magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), optical imaging techniques, image-guided surgery, as well as improving the sensitization of radio-resistant cells to radiotherapy treatment. This review discusses the characteristics of GB and NB cancers, related treatment challenges as well as the potential of CTX and its functionalized NP formulations as targeting systems for diagnostic, therapeutic, and theranostic purposes. It also provides insights into the potential mechanisms through which CTX crosses the BBB to bind cancer cells and provides suggestions for the development and application of novel CTX-based formulations for the diagnosis and treatment of GB and NB in the future.
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Affiliation(s)
- Taahirah Boltman
- Department of Medical Biosciences, University of the Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa
| | - Mervin Meyer
- Department of Science and Innovation/Mintek Nanotechnology Innovation Centre, Biolabels Node, Department of Biotechnology, University of the Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa
| | - Okobi Ekpo
- Department of Anatomy and Cellular Biology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi P.O. Box 127788, United Arab Emirates
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2
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Cid-Uribe JI, Veytia-Bucheli JI, Romero-Gutierrez T, Ortiz E, Possani LD. Scorpion venomics: a 2019 overview. Expert Rev Proteomics 2019; 17:67-83. [DOI: 10.1080/14789450.2020.1705158] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Jimena I. Cid-Uribe
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - José Ignacio Veytia-Bucheli
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Teresa Romero-Gutierrez
- Departamento de Ciencias Computacionales, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Guadalajara, Mexico
| | - Ernesto Ortiz
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Lourival D. Possani
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
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3
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Aissaoui D, Mlayah-Bellalouna S, Jebali J, Abdelkafi-Koubaa Z, Souid S, Moslah W, Othman H, Luis J, ElAyeb M, Marrakchi N, Essafi-Benkhadir K, Srairi-Abid N. Functional role of Kv1.1 and Kv1.3 channels in the neoplastic progression steps of three cancer cell lines, elucidated by scorpion peptides. Int J Biol Macromol 2018; 111:1146-1155. [DOI: 10.1016/j.ijbiomac.2018.01.144] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 01/19/2018] [Accepted: 01/20/2018] [Indexed: 12/11/2022]
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4
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Ojeda PG, Wang CK, Craik DJ. Chlorotoxin: Structure, activity, and potential uses in cancer therapy. Biopolymers 2016; 106:25-36. [DOI: 10.1002/bip.22748] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/18/2015] [Accepted: 09/18/2015] [Indexed: 01/09/2023]
Affiliation(s)
- Paola G. Ojeda
- Institute for Molecular Bioscience, the University of Queensland; Brisbane QLD 4072 Australia
| | - Conan K. Wang
- Institute for Molecular Bioscience, the University of Queensland; Brisbane QLD 4072 Australia
| | - David J. Craik
- Institute for Molecular Bioscience, the University of Queensland; Brisbane QLD 4072 Australia
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5
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Pucca MB, Cerni FA, Peigneur S, Bordon KCF, Tytgat J, Arantes EC. Revealing the Function and the Structural Model of Ts4: Insights into the "Non-Toxic" Toxin from Tityus serrulatus Venom. Toxins (Basel) 2015; 7:2534-50. [PMID: 26153865 PMCID: PMC4516927 DOI: 10.3390/toxins7072534] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 06/20/2015] [Accepted: 06/25/2015] [Indexed: 01/21/2023] Open
Abstract
The toxin, previously described as a "non-toxic" toxin, was isolated from the scorpion venom of Tityus serrulatus (Ts), responsible for the most severe and the highest number of accidents in Brazil. In this study, the subtype specificity and selectivity of Ts4 was investigated using six mammalian Nav channels (Nav1.2→Nav1.6 and Nav1.8) and two insect Nav channels (DmNav1 and BgNav). The electrophysiological assays showed that Ts4 specifically inhibited the fast inactivation of Nav1.6 channels, the most abundant sodium channel expressed in the adult central nervous system, and can no longer be classified as a "non-toxic peptide". Based on the results, we could classify the Ts4 as a classical α-toxin. The Ts4 3D-structural model was built based on the solved X-ray Ts1 3D-structure, the major toxin from Ts venom with which it shares high sequence identity (65.57%). The Ts4 model revealed a flattened triangular shape constituted by three-stranded antiparallel β-sheet and one α-helix stabilized by four disulfide bonds. The absence of a Lys in the first amino acid residue of the N-terminal of Ts4 is probably the main responsible for its low toxicity. Other key amino acid residues important to the toxicity of α- and β-toxins are discussed here.
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Affiliation(s)
- Manuela B Pucca
- Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café, s/n, Ribeirão Preto, SP 14040-903, Brazil.
| | - Felipe A Cerni
- Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café, s/n, Ribeirão Preto, SP 14040-903, Brazil.
| | - Steve Peigneur
- Toxicology and Pharmacology, University of Leuven, O&N 2, Herestraat 49, P.O. Box 922, Leuven 3000, Belgium.
| | - Karla C F Bordon
- Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café, s/n, Ribeirão Preto, SP 14040-903, Brazil.
| | - Jan Tytgat
- Toxicology and Pharmacology, University of Leuven, O&N 2, Herestraat 49, P.O. Box 922, Leuven 3000, Belgium.
| | - Eliane C Arantes
- Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Av. do Café, s/n, Ribeirão Preto, SP 14040-903, Brazil.
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6
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Hmed B, Serria HT, Mounir ZK. Scorpion peptides: potential use for new drug development. J Toxicol 2013; 2013:958797. [PMID: 23843786 PMCID: PMC3697785 DOI: 10.1155/2013/958797] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 05/19/2013] [Accepted: 05/20/2013] [Indexed: 12/13/2022] Open
Abstract
Several peptides contained in scorpion fluids showed diverse array of biological activities with high specificities to their targeted sites. Many investigations outlined their potent effects against microbes and showed their potential to modulate various biological mechanisms that are involved in immune, nervous, cardiovascular, and neoplastic diseases. Because of their important structural and functional diversity, it is projected that scorpion-derived peptides could be used to develop new specific drugs. This review summarizes relevant findings improving their use as valuable tools for new drugs development.
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Affiliation(s)
- BenNasr Hmed
- Laboratory of Pharmacology, Medicine Faculty of Sfax, Street of Majida Boulila, 3029 Sfax, Tunisia
| | - Hammami Turky Serria
- Laboratory of Pharmacology, Medicine Faculty of Sfax, Street of Majida Boulila, 3029 Sfax, Tunisia
| | - Zeghal Khaled Mounir
- Laboratory of Pharmacology, Medicine Faculty of Sfax, Street of Majida Boulila, 3029 Sfax, Tunisia
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7
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Mcferrin MB, Sontheimer H. A role for ion channels in glioma cell invasion. NEURON GLIA BIOLOGY 2012; 2:39-49. [PMID: 16520829 PMCID: PMC1389710 DOI: 10.1017/s17440925x06000044] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Many cells, including neuronal and glial progenitor cells, stem cells and microglial cells, have the capacity to move through the extracellular spaces of the developing and mature brain. This is particularly pronounced in astrocyte-derived tumors, gliomas, which diffusely infiltrate the normal brain. Although a significant body of literature exists regarding signals that are involved in the guidance of cells and their processes, little attention has been paid to cell-shape and cell-volume changes of migratory cells. However, extracellular spaces in the brain are very narrow and represent a major obstacle that requires cells to dynamically regulate their volume. Recent studies in glioma cells show that this involves the secretion of Cl(-) and K(+) with water. Pharmacological inhibition of Cl(-) channels impairs their ability to migrate and limits tumor progression in experimental tumor models. One Cl(-)-channel inhibitor, chlorotoxin, is currently in Phase II clinical trials to treat malignant glioma. This article reviews our current knowledge of cell-volume changes and the role of ion channels during the migration of glioma cells. It also discusses evidence that supports the importance of channel-mediated cell-volume changes in the migration of immature neurons and progenitor cells during development. New unpublished data is presented, which demonstrates that Cl(-) and K(+) channels involved in cell shrinkage localize to lipid-raft domains on the invadipodia of glioma cells and that their presence might be regulated by trafficking of these proteins in and out of lipid rafts.
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Affiliation(s)
| | - Harald Sontheimer
- Correspondence should be addressed to: Harald Sontheimer, Ph.D. Department of Neurobiology, The University of Alabama at Birmingham 1119 6th Ave S. CIRC 545 USA phone: +1 205 975 5805 fax: +1 205 975 5518
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8
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Zhao J, Qiao W, Zhang Y, Shao X. Preparation and In Vitro Evaluation of 131I-BmK CT as a Glioma-Targeted Agent. Cancer Biother Radiopharm 2010; 25:353-9. [PMID: 20578841 DOI: 10.1089/cbr.2009.0704] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Jinhua Zhao
- Department of Nuclear Medicine, The First People's Hospital, Shanghai Jiaotong University, Shanghai, People's Republic of China
| | - Wenli Qiao
- Department of Nuclear Medicine, The First People's Hospital, Shanghai Jiaotong University, Shanghai, People's Republic of China
| | - Yuna Zhang
- Department of Nuclear Medicine, The First People's Hospital, Shanghai Jiaotong University, Shanghai, People's Republic of China
| | - Xiaoxia Shao
- Institute of Protein Research, Tongji University, Shanghai, People's Republic of China
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9
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Abstract
In mammalian brain, neurons and astrocytes are reported to express various chloride and anion channels, but the evidence for functional expression of Ca(2+)-activated anion channel (CAAC) and its molecular identity have been lacking. Here we report electrophysiological evidence for the CAAC expression and its molecular identity by mouse Bestrophin 1 (mBest1) in astrocytes of the mouse brain. Using Ca(2+) imaging and perforated-patch-clamp analysis, we demonstrate that astrocytes displayed an inward current at holding potential of -70 mV that was dependent on an increase in intracellular Ca(2+) after G(alphaq)-coupled receptor activation. This current was mediated mostly by anions and was sensitive to well known anion channel blockers such as niflumic acid, 5-nitro-2(3-phenylpropylamino)-benzoic acid, and flufenamic acid. To find the molecular identity of the anion channel responsible for the CAAC current, we analyzed the expression of candidate genes and found that the mRNA for mouse mBest1 is predominantly expressed in acutely dissociated or cultured astrocytes. Whole-cell patch-clamp analysis using HEK293T cells heterologously expressing full-length mBest1 showed a Ca(2+)-dependent current mediated by mBest1, with a complete impairment of the current by a putative pore mutation, W93C. Furthermore, mBest1-mediated CAAC from cultured astrocytes was significantly reduced by expression of mBest1-specific short hairpin RNA (shRNA), suggesting that the CAAC is mediated by a channel encoded by mBest1. Finally, hippocampal CA1 astrocytes in hippocampal slice also showed mBest1-mediated CAAC because it was inhibited by mBest1-specific shRNA. Collectively, these data provide molecular evidence that the mBest1 channel is responsible for CAAC function in astrocytes.
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10
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Young RC, Bemis A. Calcium-activated chloride currents prolongs the duration of contractions in pregnant rat myometrial tissue. Reprod Sci 2009; 16:734-9. [PMID: 19380901 DOI: 10.1177/1933719109334965] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We investigated the importance of pharmacologically blocking calcium-activated chloride (I(Cl(Ca))) and L-type calcium currents on isometric contractions of strips of D21 pregnant rat myometrial tissue, while simultaneously measuring the electrical activity of the tissue strips with extracellular contact electrodes. When measured with contact electrodes, the duration of the spiking activity directly reflects the duration of the tissue-level plateau potential. We correlated the number of spikes, durations of spiking activity, and the spiking frequencies with changes of the area under the force curves as a function of exposure to low doses of anthracene-9-carboxylate (9-AC, a non-specific Cl channel blocker), chlorotoxin (a specific I(Cl(Ca)) blocker) and nifedipine (an L-type calcium channel blocker). The area under the force curve was measured only during spiking electrical activity, thereby separating pharmacological effects on tissue relaxation from those that modulate force production. Blocking chloride channels reduced impulse, shortened the duration of spiking activity, and reduced the number of spikes generated in each contraction. This was observed without a change in the frequency of spike production or a reduction of peak force. Nifedipine reduced impulse, shortened the duration of spiking activity, and reduced the number of spikes. In contrast to chloride channel blockade, nifedipine reduced maximum spike frequency and peak force. Taken together, our data suggest that blocking L-type calcium channels reduces impulse directly by reducing peak force, and indirectly by reducing activation of I(Cl(Ca)) , which shortens the duration of the contraction.
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Affiliation(s)
- Roger C Young
- Department of Obstetrics and Gynecology, University of Vermont, Burlington, Vermont 05405, USA.
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11
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Fuller MD, Thompson CH, Zhang ZR, Freeman CS, Schay E, Szakács G, Bakos E, Sarkadi B, McMaster D, French RJ, Pohl J, Kubanek J, McCarty NA. State-dependent inhibition of cystic fibrosis transmembrane conductance regulator chloride channels by a novel peptide toxin. J Biol Chem 2007; 282:37545-55. [PMID: 17951250 DOI: 10.1074/jbc.m708079200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Peptide toxins from animal venom have been used for many years for the identification and study of cation-permeable ion channels. However, no peptide toxins have been identified that interact with known anion-selective channels, including cystic fibrosis transmembrane conductance regulator (CFTR), the protein defective in cystic fibrosis and a member of the ABC transporter superfamily. Here, we describe the identification and initial characterization of a novel 3.7-kDa peptide toxin, GaTx1, which is a potent and reversible inhibitor of CFTR, acting from the cytoplasmic side of the membrane. Thus, GaTx1 is the first peptide toxin identified that inhibits a chloride channel of known molecular identity. GaTx1 exhibited high specificity, showing no effect on a panel of nine transport proteins, including Cl(-) and K(+) channels, and ABC transporters. GaTx1-mediated inhibition of CFTR channel activity is strongly state-dependent; both potency and efficacy are reduced under conditions of elevated [ATP], suggesting that GaTx1 may function as a non-competitive inhibitor of ATP-dependent channel gating. This tool will allow the application of new quantitative approaches to study CFTR structure and function, particularly with respect to the conformational changes that underlie transitions between open and closed states.
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Affiliation(s)
- Matthew D Fuller
- Program in Molecular and Systems Pharmacology, Emory University, Atlanta, GA 30322, USA
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12
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Welch NC, Lalonde MR, Barnes S, Kelly MEM. Calcium-activated chloride channels in müller cells acutely isolated from tiger salamander retina. Glia 2006; 53:74-80. [PMID: 16158415 DOI: 10.1002/glia.20270] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Ca(2+)-activated chloride channels were identified with whole-cell patch-clamp recording techniques in salamander retinal Müller cells. Cl(Ca) channels were activated by membrane depolarizations that elicited Ca2+ influx or the application of the Ca2+ ionophore, ionomycin. The Ca channel blocker, Cd2+, abolished the Cl(Ca) channel tail currents. Increasing the duration of the depolarizing pulse resulted in enhancement of the Cl(Ca) channel tail current. Repetitive depolarizations with rapid pulses to +20 mV produced a buildup of I(Cl(Ca)), which reversed at 0 mV in symmetrical [Cl-] and at -40 mV when intracellular [Cl-] was reduced to 10% of the external concentration. I(Cl(Ca)) was blocked by the Cl channel blocker niflumic acid, while niflumic acid had no effect on voltage-gated Ca channels. These results offer the first demonstration of Cl(Ca) channels in a nonastrocytic glial cell and expand our understanding of the functional capacities of retinal glial cells.
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Affiliation(s)
- Nicole C Welch
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
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13
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Abstract
Many cells, including neuronal and glial progenitor cells, stem cells and microglial cells, have the capacity to move through the extracellular spaces of the developing and mature brain. This is particularly pronounced in astrocyte-derived tumors, gliomas, which diffusely infiltrate the normal brain. Although a significant body of literature exists regarding signals that are involved in the guidance of cells and their processes, little attention has been paid to cell-shape and cell-volume changes of migratory cells. However, extracellular spaces in the brain are very narrow and represent a major obstacle that requires cells to dynamically regulate their volume. Recent studies in glioma cells show that this involves the secretion of Cl− and K+ with water. Pharmacological inhibition of Cl− channels impairs their ability to migrate and limits tumor progression in experimental tumor models. One Cl−-channel inhibitor, chlorotoxin, is currently in Phase II clinical trials to treat malignant glioma. This article reviews our current knowledge of cell-volume changes and the role of ion channels during the migration of glioma cells. It also discusses evidence that supports the importance of channel-mediated cell-volume changes in the migration of immature neurons and progenitor cells during development. New unpublished data is presented, which demonstrates that Cl− and K+ channels involved in cell shrinkage localize to lipid-raft domains on the invadipodia of glioma cells and that their presence might be regulated by trafficking of these proteins in and out of lipid rafts.
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14
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Tan PTJ, Srinivasan KN, Seah SH, Koh JLY, Tan TW, Ranganathan S, Brusic V. Accurate prediction of scorpion toxin functional properties from primary structures. J Mol Graph Model 2005; 24:17-24. [PMID: 15950506 DOI: 10.1016/j.jmgm.2005.01.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Accepted: 01/31/2005] [Indexed: 10/25/2022]
Abstract
Scorpion toxins are common experimental tools for studies of biochemical and pharmacological properties of ion channels. The number of functionally annotated scorpion toxins is steadily growing, but the number of identified toxin sequences is increasing at much faster pace. With an estimated 100,000 different variants, bioinformatic analysis of scorpion toxins is becoming a necessary tool for their systematic functional analysis. Here, we report a bioinformatics-driven system involving scorpion toxin structural classification, functional annotation, database technology, sequence comparison, nearest neighbour analysis, and decision rules which produces highly accurate predictions of scorpion toxin functional properties.
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Affiliation(s)
- Paul T J Tan
- Laboratories for Information Technology, Knowledge Discovery Department, Institute for Infocomm Research, Singapore 119613, Singapore
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15
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Abstract
Calcium-activated chloride channels (CaCCs) play important roles in cellular physiology, including epithelial secretion of electrolytes and water, sensory transduction, regulation of neuronal and cardiac excitability, and regulation of vascular tone. This review discusses the physiological roles of these channels, their mechanisms of regulation and activation, and the mechanisms of anion selectivity and conduction. Despite the fact that CaCCs are so broadly expressed in cells and play such important functions, understanding these channels has been limited by the absence of specific blockers and the fact that the molecular identities of CaCCs remains in question. Recent status of the pharmacology and molecular identification of CaCCs is evaluated.
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Affiliation(s)
- Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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16
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Sontheimer H. Ion channels and amino acid transporters support the growth and invasion of primary brain tumors. Mol Neurobiol 2004; 29:61-71. [PMID: 15034223 PMCID: PMC2548410 DOI: 10.1385/mn:29:1:61] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2003] [Accepted: 07/24/2003] [Indexed: 11/11/2022]
Abstract
The malignant growth of glial support cells causes gliomas, highly invasive, primary brain tumors that are largely resistant to therapy. Individual tumor cells spread by active cell migration, invading diffusely into the normal brain. This process is facilitated by Cl- channels that endow glioma cells with an enhanced ability to quickly adjust their shape and cell volume to fit the narrow and tortuous extracellular brain spaces. Once satellite tumors enlarge, their growth is limited by the spatial constraints imposed by the bony cavity of the skull and spinal column. Glioma cells circumvent this limitation by active destruction of peritumoral neural tissue through the release of glutamate, inducing peritumoral seizures and ultimately excitotoxic neuronal cell death. Hence, primary brain tumors support their unusual biology by taking advantage of ion channels and transporters that are designed to support ion homeostatic functions in normal brain.
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Affiliation(s)
- Harald Sontheimer
- Department of Neurobiology and Civitan International Research Center, the University of Alabama at Birmingham, Birmingham, AL, USA.
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17
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Functional coupling between sulfonylurea receptor type 1 and a nonselective cation channel in reactive astrocytes from adult rat brain. J Neurosci 2003. [PMID: 13679426 DOI: 10.1523/jneurosci.23-24-08568.2003] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We previously identified a novel, nonselective cation channel in native reactive (type R1) astrocytes (NR1As) from injured rat brain that is regulated by cytoplasmic Ca2+ and ATP (NC(Ca-ATP)) and exhibits sensitivity to block by adenine nucleotides similar to that of sulfonylurea receptor type 1 (SUR1). Here we show that SUR1 is involved in regulation of this channel. NR1As within the site of injury and after isolation exhibited specific binding of FITC-tagged glibenclamide and were immunolabeled with anti-SUR1 antibody, but not with anti-SUR2, anti-Kir6.1 or anti-Kir6.2 antibodies, indicating absence of ATP-sensitive K+ (KATP) channels. RT-PCR confirmed transcription of mRNA for SUR1 but not SUR2. Several properties previously associated exclusively with SUR1-regulated KATP channels were observed in patch-clamp experiments using Cs+ as the charge carrier: (1) the sulfonylureas, glibenclamide and tolbutamide, inhibited NCCa-ATP channels with EC50 values of 48 nm and 16.1 microm, respectively; (2) inhibition by sulfonylureas was lost after exposure of the intracellular face to trypsin or anti-SUR1 antibody; (3) channel inhibition was caused by a change in kinetics of channel closing, with no change in channel amplitude or open-channel dwell times; and (4) the SUR activator ("KATP channel opener"), diazoxide, activated the NCCa-ATP channel, whereas pinacidil and cromakalin did not. Also, glibenclamide prevented cell blebbing after ATP depletion, whereas blebbing was produced by exposure to diazoxide. Our data indicate that SUR1 is functionally coupled to the pore-forming portion of the NC(Ca-ATP) channel, providing the first demonstration of promiscuity of SUR1 outside of the K+ inward rectifier family of channels.
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Abstract
Venomous animals have evolved a vast array of peptide toxins for prey capture and defence. These peptides are directed against a wide variety of pharmacological targets, making them an invaluable source of ligands for studying the properties of these targets in different experimental paradigms. A number of these peptides have been used in vivo for proof-of-concept studies, with several having undergone preclinical or clinical development for the treatment of pain, diabetes, multiple sclerosis and cardiovascular diseases. Here we survey the pharmacology of venom peptides and assess their therapeutic prospects.
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Affiliation(s)
- Richard J Lewis
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia 4072, Australia.
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