
Human CD27 is a lymphocyte specific member of the tumor necrosis factor (TNF) receptor family and is found primarily on peripheral blood T cells and on a subpopulation of B cells and NK cells. The ligand for CD27 is CD70, which is a member of the TNF ligand superfamily (2, 3). Antibody M-T271 does not block the interaction between CD27 and CD70.
Isotype: Murine IgG1
Immunogen: T cell line (from patient with CLL)
Specificity: Antibody M-T271 recognizes the dimeric CD27 molecule of approximately 110 kd (1, 4) but does not block the interaction between CD70 and CD27. Clone M-T271 has been shown to abrogate IL-4 production(7) or induce apoptosis(6) in MLR . Clone M-T271 is crossreactive with cynomolgus monkey CD27 (8).
References:
1. Leukocyte Typing IV (W. Knapp, et al, eds.) Oxford University Press, Oxford, (1989) p. 350-352.
2. K. Agematsu, et al, (1994) J Immunol 153: 1421-1429.
3. R.Q. Hintzen, et al, (1994) Immunol Today 15: 307-311.
4. Leukocyte Typing V (S.F. Schlossman, et al, eds.) Oxford University Press, Oxford, (1995) p. 356-360, 435-437.
5. K. Agematsu, et al, (1995) J Immunol 154: 3627-3635.
6. Wischhusen J, M Weller, et al. (2002) Cancer Res 62: 2592-2599
7. Palmer DR, U Krzych. Eur J Immunol 32(3): 652-661.
8. Yoshino N, Honda M, et al. (2000) Exp Anim 49(2):97-110.
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QianWang,JessamyTiffen,CharlesG.Bailey,MelanieL.Lehman,WilliamRitchie,LadanFazli,CynthiaMetierre,Yue(Julie)Feng,EstelleLi,MartinGleave,GrantBuchanan,ColleenC.Nelson,JohnE.J.Rasko,JeffHolst
Correspondenceto:JeffHolst,PhD,OriginsofCancerLaboratory,LockedBag6,Newtown,NSW2042Australia.(e-mail:j.holst@centenary.org.au).
BackgroundL-typeaminoacidtransporters(LATs)uptakeneutralaminoacidsincludingL-leucineintocells,stimulatingmammaliantargetofrapamycincomplex1signalingandproteinsynthesis.LAT1andLAT3areoverexpressedatdifferentstagesofprostatecancer,andtheyareresponsIBLeforincreasingnutrientsandstimulatingcellgrowth.
MethodsWeexaminedLAT3proteinexpressioninhumanprostatecancertissuemicroarrays.LATfunctionwasinhibitedusingaleucineanalog(BCH)inandrogen-dependentand-independentenvironments,withgeneexpressionanalyzedbymicroarray.APC-3xenograftmousemodelwasusedtostudytheeffectsofinhibitingLAT1andLAT3expression.ResultswereanalyzedwiththeMann-WhitneyUorFisherexacttests.Allstatisticaltestsweretwo-sided.
ResultsLAT3proteinwasexpressedatallstagesofprostatecancer,withastatisticallysignificantdecreaseinexpressionafter4–7monthsofneoadjuvanthormonetherapy(4–7monthmean=1.571;95%confidenceinterval=1.155to1.987vs0month=2.098;95%confidenceinterval=1.962to2.235;P=.0187).InhibitionofLATfunctionledtoactivatingtranscriptionfactor4–mediatedupregulationofaminoacidtransportersincludingASCT1,ASCT2,and4F2hc,allofwhichwerealsoregulatedviatheandrogenreceptor.LATinhibitionsuppressedM-phasecellcyclegenesregulatedbyE2Ffamilytranscriptionfactorsincludingcriticalcastration-resistantprostatecancerregulatorygenesUBE2C,CDC20,andCDK1.InsilicoanalysisofBCH-downregulatedgenesshowedthat90.9%arestatisticallysignificantlyupregulatedinmetastaticcastration-resistantprostatecancer.Finally,LAT1orLAT3knockdowninxenograftsinhibitedtumorgrowth,cellcycleprogression,andspontaneousmetastasisinvivo.
ConclusionInhibitionofLATtransportersmayprovideanoveltherapeutictargetinmetastaticcastration-resistantprostatecancer,viasuppressionofmammaliantargetofrapamycincomplex1activityandM-phasecellcyclegenes.
L-typeaminoacidtransporters(LATs)supplycellswithlargeneutralaminoacids,whicharenotonlyrequiredforproteinsynthesisbutalsocontributetovarioussignalingpathways.Intracellularleucinelevelsaresensedbytheleucyl-transferRNAsynthetase,previouslyknowntocatalyzetheadenosinetriphosphate–dependentligationofL-leucinetotransferRNAduringproteinsynthesis(1,2).Leucyl-transferRNAsynthetaseactivatestheRagguanosinetriphosphatasecomplexandbindstoRaptortoactivatemammaliantargetofrapamycincomplex1(mTORC1)signalingonthesurfaceoflysosomes(1–3).Inthiswayleucineisnotonlyanessentialaminoacidbutactsasarate-limitingsignalingmoleculeinthemTORC1pathway.
Incellsdeprivedofaminoacids,thereisanaccumulationofunchargedtransferRNA,whichbindstoandactivatesthegeneralcontrolnonrepressed2(GCN2)kinase.Inturn,GCN2phosphorylatesthetranslationinitiationfactor2α(eIF2α)onserine51,triggeringtranslationalupregulationofactivatingtranscriptionfactor(ATF)4(4).ATF4itselfupregulatestheexpressionofaminoacidtransportersasameansofrestoringintracellularaminoacidlevels(5).Therefore,understandinghowaminoacidtransportersregulateintracellularleucinelevels,andgeneratingnovelinhibitorsofthesetransporters,mayleadtopotentsuppressorsofmTORC1signaling.
ThetwodistinctfamiliesofLATsare1)solutecarrier7(SLC7)members(LAT1/SLC7A5andLAT2/SLC7A8),whichmediateNa+-independentneutralaminoacidexchangeasheterodimerswiththe4F2cell-surfaceantigenheavychain(4F2hc/SLC3A2/CD98)glycoprotein(6,7);and2)SLC43proteins(LAT3/SLC43A1andLAT4/SLC43A2)thatmediateNa+-independentuniportofneutralaminoacids(8,9).AlthoughtheexpressionofeachLATmembervariesdramaticallyindifferenttissues,thesetransportersarecommonlyupregulatedincancer.IncreasedLAT1expressionhasbeendetectedinlungcancer,coloncancer,breastcancer,headandneckcancer,genitalcancers,andsofttissuesarcomas(10–12).WeandothershaveshownthatLAT1andLAT3areoverexpressedinprostatecancer(11–14),withLAT1expressionincreasedinmetastasiscomparedwithprimarycancer(10,12).
WehypothesizedthatinhibitionofLAT1andLAT3mayofferaneffectivetherapeuticapproachforprostatecancer.
转运体是介导分子或离子转运跨过生物膜的物质。通常是蛋白质或酶。说得简单一点就是“运输工具”
受体是能与细胞外专一信号分子(配体)结合引起细胞反应的蛋白质。受体与配体结合即发生分子构象变化,从而引起细胞反应,如介导细胞间信号转导、细胞间黏合、细胞胞吞等细胞过程。它起的是“传达员” 的作用

