简介：Amurinemacrophage-likecellline,J774,acquried,inresponsetoLPS,anabilitytokilltumornecrosisfactor（TNF）-insensitivetargetP815mastocytomacells,whereasanothercellline,P388D1,didnot.LPS-triggeredsignalingmechanismsbetweenthetwocelllineswerecomparedwithanaimtoinquireaboutthepossiblenatureoftheabove-mentioneddifference.TheresultsshowedthattwocelllinesrespondtoLPS-treatmentbyparallelactivationofbothphospholipasesCandA2（PLCandPLA2）toapproximatelythesameextent.ThemaximumresponseofbothenzymesofJ774cellswasnotedwithin10minofthetreatment,whereasthatofP388D1cellsrequiredmorethan20min.TheotherpropertiesofLPS-responsiveenzymesstudiedweresimilarbetweentwocelllines,ineludingActivationofPLCandPLA2andPKCinmacrophagesbyLPSCa2+augmentationofenzymeactivation,participationofguaninenucleotidebinding（G）proteinsintheinitialactivationprocesses,andinhibitionofenzymeactivationbythepriortreatmentofcellswithcholeraorpartussistoxinsetc.Moreover,LPS-triggeredactivationofPLCandPLA2wasfoundtobefollowedbytheincreaseofPKCactivitiesinbothcelllines.Inspiteofthesesimilarities,J774cellspossessedbothbasicandacidicformsofPKCactivities,whileP388D1cellsownedonlyPKCofbasicform.Nevertheless,thequestionwhyJ774cells,butnotP388D1cells,canacquirethetumoricidalactiyity,aganistP815cellsfollowingLPS-treatmentremainstobeanswered.

简介：OverexpressionandactivationofHER-2/neu(alsoknownasc-erbB-2),aproto-oncogene,wasfoundinabout30%ofhumanbreastcancers,promotingcancergrowthandmakingcancercellsresistanttochemo-andradio-therapy.Wild-typep53iscrucialinregulatingcellgrowthandapoptosisandisfoundtobemutatedordeletedin60-70%ofhumancancers.Andsomecancerswithawild-typep53donothavenormalp53function,suggestingthatitisimplicatedinacomplexprocessregulatedbymanyfactors.Inthepresentstudy,weshowedthattheoverexpressionofHER-2/neucoulddecreasetheamountofwild-typep53proteinviaactivatingPI3Kpathway,aswellasinducingMDM2nucleartranslocationinMCF7humanbreastcancercells.BlockageofPI3KpathwaywithitsspecificinhibitorLY294002causedG1-Sphasearrest,decreasedcellgrowthrateandincreasedchemo-andradio-therapeuticsensitivityinMCF7cellsexpressingwild-typep53.However,itdidnotincreasethesensitivitytoadriamycininMDA-MB-453breastcancercellscontainingmutantp53.OurstudyindicatesthatblockingPI3KpathwayactivationmediatedbyHER-2/neuoverexpressionmaybeusefulinthetreatmentofbreasttumorswithHER-2/neuoverexpressionandwild-typep53.