Chlorotoxin(Cltx) isaneurotoxinthatwasoriginallyisolatedfromthevenomofLeiurusquinquestriatus. Chlorotoxin isaspecificligandof gliomacells. Chlorotoxin bindstoCl–channels(smallconductanceepithelialchloridechannels)inthebrainandspinalcordandinhibitsCl– influx. Chlorotoxin mostprobablyactsasaspecificblocker,althoughresiduesbothinsideandoutsideoftheporeregionoftheCl– channelsparticipateinchlorotoxinbinding.Itwasdemonstratedthat chlorotoxin inhibitsspecificallytheactivityof matrixmetalloproteinase-2(MMP-2) withoutaffectingMMP-1,MMP-3andMMP-9.MMP-2areupregulatedingliomacellsandrelatedcellsmaking chlorotoxin apromisingantitumoraldruganddiagnosistool.
Description:
AAsequence: Met-Cys2-Met-Pro-Cys5-Phe-Thr-Thr-Asp-His-Gln-Met-Ala-Arg-Lys-Cys16-Asp-Asp-Cys19-Cys20-Gly-Gly-Lys-Gly-Arg-Gly-Lys-Cys28-Tyr-Gly-Pro-Gln-Cys33-Leu-Cys35-Arg-NH2
Disulfidebonds: Cys2-Cys19,Cys5-Cys28,Cys16-Cys33 andCys20-Cys35
Length(aa): 36
Formula: C158H249N53O47S11
MolecularWeight: 3995.8Da
Appearance: Whitelyophilizedsolid
Solubility: waterandsalinebuffer
CASnumber: [163515-35-3]Source: Synthetic
Purityrate: >95%
Reference:
Chlorotoxininhibitsgliomacellinvasionviamatrixmetalloproteinase-2
Primarybraintumors(gliomas)havetheunusualABIlitytodiffuselyinfiltratethenormalbraintherebyevADIngsurgicaltreatment.Chlorotoxinisascorpiontoxinthatspecificallybindstothesurfaceofgliomacellsandimpairstheirabilitytoinvade.UsingarecombinantHis-CltxweisolatedandidentifiedtheprincipalCltxreceptoronthesurfaceofgliomacellsasmatrixmetalloproteinase-2(MMP-2).MMP-2isspecificallyup-regulatedingliomasandrelatedcancers,butisnotnormallyexpressedinbrain.WedemonstratethatCltxspecificallyandselectivelyinteractswithMMP-2isoforms,butnotwithMMP-1,-3,and-9,whicharealsoexpressedinmalignantgliomacells.Importantly,weshowthattheanti-invasiveeffectofCltxongliomacellscanbeexplainedbyitsinteractionswithMMP-2.CltxexertsadualeffectonMMP-2:itinhibitstheenzymaticactivityofMMP-2andcausesareductioninthesurfaceexpressionofMMP-2.ThesefindingssuggestthatCltxisaspecificMMP-2inhibitorwithsignificanttherapeuticpotentialforgliomasandotherdiseasesthatinvoketheactivityofMMP-2.
DeshaneJ.etal.(2003)Chlorotoxininhibitsgliomacellinvasionviamatrixmetalloproteinase-2.JBiolChem. PMID:12454020
Chlorotoxin,ascorpion-derivedpeptide,specificallybindstogliomasandtumorsofneuroectodermalorigin.
Highlymigratoryneuroectodermalcellsshareacommonembryonicoriginwithcellsofthecentralnervoussystem(CNS).Theyincludeenteric,parasympathetic,sympathoadrenal,andsensoryneuronsoftheperipheralnervoussystem,Schwanncells,melanocytes,endocrinecells,andcellsformingconnectivetissueofthefaceandneck.Becauseoftheircommonembryologicorigin,thesecellsandthetumorsthatderivefromthemcansharegeneticandantigenicphenotypeswithgliomas,tumorsderivedfromCNSglia.Werecentlydiscoveredthatchlorotoxin(ClTx),a4-kDpeptidepurifiedfromLeiurusquinquestriatusscorpion,isahighlyspecificMarkerforgliomacellsinbiopsytissues(Soroceanuetal.CancerRes58:4871-4879,1998)thatcantargettumorsinanimalmodels.WereportonthespecificityofClTxasamarkerfortumorsofneuroectodermaloriginthatincludeperipheralneuroectodermaltumors(PNET)andgliomas.Specifically,wehistochemicallystainedfrozenandparaffintissuesectionsofhumanbiopsytissuesfrom262patientswithasyntheticallymanufacturedandBIOLOGicallyactiveClTxbearinganN-terminalbiotin.Thevastmajority(74of79)ofprimaryhumanbraintumorsinvestigatedshowedabundantbindingofClTxwithgreaterthan90%ClTx-positivecellsineachsection.Bycomparison,32biopsiesofuninvolvedbrainusedforcomparisonwerelargelyClTx-negative,withonlyafewisolatedreactiveastrocytesshowingsomeClTxbinding.However,aswithgliomas,thevastmajorityofPNETsexaminedshowedspecificClTxbinding(31of34).Theseincludemedulloblastomas(4of4),neuroblastomas(6of7),ganglioneuromas(4of4),melanomas(7of7),adrenalpheochromocytomas(5of6),primitivePNET(1),smallcelllungcarcinoma(2of3),andEwing’ssarcoma(2of2).Underidenticalstainingconditions,normaltissuesfrombrain,skin,kidney,andlungwereconsistentlynegativeforClTx.Theseresultssuggestthatchlorotoxinisareliableandspecifichistopathologicalmarkerfortumorsofneuroectodermaloriginandthatchlorotoxinderivativeswithcytolyticactivitymayhavetherapeuticpotentialforthesecancers.
LyonsSA.,etal.(2002)Chlorotoxin,ascorpion-derivedpeptide,specificallybindstogliomasandtumorsofneuroectodermalorigin.Glia. PMID:12112367
Purificationandcharacterizationofchlorotoxin,achloridechannelligandfromthevenomofthescorpion
WehavepreviouslydemonstratedthatthevenomofthescorpionLeiurusquinquestriatusblockssmall-conductanceCl-channels,derivedfromepithelialcells,whenappliedtothecytoplasmicsurface.Wehavenowpurifiedtonearhomogeneity,andcharacterized,thecomponentresponsIBLeforthisblockingactivity.Itisasmallbasicpeptideof4,070Da.Theprimaryaminoacidstructureshowsconsiderablehomologytoaclassofpreviouslydescribedputativeshortinsectotoxins.AbriefcharacterizationofthekineticsofCl-channelblockaswellasademonstrationoftoxicitytoarthropodsisalsopresented.
DebinJA, etal.Purificationandcharacterizationofchlorotoxin,achloridechannelligandfromthevenomofthescorpion.Am.J.Physiol. PMID:8383429
ModulationofgliomacellmigrationandinvasionusingCl(-)andK(+)ionchannelblockers
Humanmalignantgliomasarehighlyinvasivetumors.Mechanismsthatallowgliomacellstodisseminate,migratingthroughthenarrowextracellularbrainspacesarepoorlyunderstood.Werecentlydemonstratedexpressionoflargevoltage-dependentchloride(Cl(-))currents,selectivelyexpressedbyhumangliomacellsinvitroandinsitu(Ullrichetal.,1998).CurrentsaresensitivetoseveralCl(-)channelblockers,includingchlorotoxin(Ctx),(UllrichandSontheimer;1996;Ullrichetal;1996),tetraethylammoniumchloride(TEA),andtamoxifen(RansomandSontheimer,1998).UsingTranswellmigrationassays,weshowthatblockadeofgliomaCl(-)channelsspecificallyinhibitstumorcellmigrationinadose-dependentmanner.Ctx(5microM),tamoxifen(10microM),andTEA(1mM)alsopreventedinvasionofhumangliomacellsintofetalratbrainaggregates,usedasaninvitromodeltoassesstumorinvasiveness.Anionreplacementstudiessuggestthatpermeationofchlorideionsthroughgliomachloridechannelisobligatoryforcellmigration.Osmoticallyinducedcellswellingandsubsequentregulatoryvolumedecrease(RVD)inculturedgliomacellswerereversiblypreventedby1mMTEA,10microMtamoxifen,andirreversiblyblockedby5microMCtxaddedtothehypotonicmedia.Cl(-)fluxesassociatedwithadaptiveshapechangeselicitedbycellswellingandRVDingliomacellswereinhibitedby5microMCtx,10microMtamoxifen,and1mMTEA,asdeterminedusingtheCl(-)-sensitivefluorescentdye6-methoxy-N-ethylquinoliniumiodide.Collectively,thesedatasuggestthatchloridechannelsingliomacellsmayenabletumorinvasiveness,presumablybyfacilitatingcellshapeandcellvolumechangesthataremoreconducivetomigrationandinvasion.
SoroceanuL.ModulationofgliomacellmigrationandinvasionusingCl(-)andK(+)ionchannelblockers. JNeurosci.PMID:10407033
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