简介：Objective:Chroniclymphocyticleukemia(CLL)andmantlecelllymphoma(MCL)cellsover-expressaguanineexchangefactor(GEF),Rasgrf-1.ThisGEFincreasesactiveRasasitcatalyzestheremovalofGDPfromRassothatGTPcanbindandactivateRas.ThisstudyaimstostudythemechanismofactionofRasgrf-1inB-cellmalignancies.Methods:N-terminustruncatedRasgrf-1variantshaveahigherGEFactivityascomparedtothefull-lengthtranscriptthereforeaMCLcelllinewithstableover-expressionoftruncatedRasgrf-1wasestablished.TheB-cellreceptor(BCR)andchemokinesignalingpathwayswerecomparedintheRasgrf-1over-expressingandacontroltransfectedcellline.Results:Cellsover-expressingtruncatedformofRasgrf-1haveahigherproliferativerateascomparedtocontroltransfectedcells.BCRwasactivatedbylowerconcentrationsofanti-IgMantibodyinRasgrf-1over-expressingcellsascomparedtocontrolcellsindicatingthatthesecellsaremoresensitivetoBCRsignaling.BCRsignalingalsophosphorylatesRasgrf-1thatfurtherincreasesitsGEFfunctionandamplifiesBCRsignaling.ThisactivationofRasgrf-1inover-expressingcellsresultedinahigherexpressionofphospho-ERK,AKT,BTKandPKC-alphaascomparedtocontrolcells.BesidesBCR,Rasgrf-1over-expressingcellswerealsomoresensitivetomicroenvironmentstimuliasdeterminedbyresistancetoapoptosis,chemotaxisandERKpathwayactivation.Conclusions:ThisGEFproteinsensitizesB-cellstoBCRandchemokinemediatedsignalingandalsoupregulatesanumberofothersignalingpathwayswhichpromotesgrowthandsurvivalofthesecells.