BackgroundInformation | I.TESTPRINCIPLE TheUPSTATEcolorimetricSTAR(SignalTransductionAssayReaction)ELISAkitisasolidphasesandwichenzymelinkedimmunosorbentassaythatprovidesafast,sensitivemethodtodetectspecificlevelsofsignalingtargetsinwholecellextracts.TheEGFRplateiscoatedwithaspecificmousemonoclonalanti-EGFRcaptureantibodyonthemicrowellsofthe96-wellclearplate.SamplelysateorthestandardincludedinthekitareincubatedinthemicrowellsallowingEGFRantigentobecapturedintheplatewells.Theplateisthenwashedtoremoveanynon-boundunspecificmaterial.Thewellsarethenincubatedwithaspecificrabbitanti-EGFRantibodytodetectthecapturedphospho-EGFR(Tyr1173)ontheplatewell.TheunbounddetectionantibodyiswashedawayfollowedbyincubationwithanHRP-conjugatedanti-rabbitantibody.Thisallowsforasensitiveenzymaticdetectionofthesample.AftertheadditionofTMBsubstrateandstopsolutiontheabsorbanceismeasuredat450nmusingaplatereader.Theentireassaytakeslessthan5hourstocompletewithminimalhands-ontime.Manyofthereagentsaresuppliedinready-touseformulationsforeaseofuse.Thekitalsoincludesastandardthatisrunasbothapositivecontrolandtodevelopastandardcurve.
II.EGFRBACKGROUND
Epidermalgrowthfactorreceptor(EGFR)isareceptortyrosinekinasethatplaysakeyroleintheregulationofessentialnormalcellularprocessesandinthepathophysiologyofhyperproliferativediseasessuchascancer.Epidermalgrowthfactorreceptor(EGFR)isareceptortyrosinekinaseknowntobeessentialformediationofbothproliferativeandsurvivalsignalstocells.ActivationoftheEGFRsignalingpathwayhasbeenlinkedwithincreasedcellproliferation,angiogenesis,metastasisanddecreasedapoptosis.EGFRisfoundinmostsolidtumorsanditsautophosphorylationactivatestheintrinsickinaseactivitytowardheterologoussubstrates,aswellascreatingdockingsitesforadapterproteinsformultipleadapterproteinstobindandnucleatesignalingcomplexesthatactivatetheRas,PI3Kinase,andPLCpathways. ManyoftheEGFRmutationsaredirectlyrelatedtovariousdiseasesandarethetargetofnumerousdrugs.Forinstance,theaminoacidsubstitutionL858RisoneofseveralheterozygousmutationsthathavebeenidentifiedinNon-Small-CellLungCancer(NSCLC)patientswhohaveclinicalresponsestotheEGFRinhibitorIressa®.ThereissomeevidencethatthesemutationsresultinelevatedactivityandenhancedsensitivitytoIressa®.InpatientswithtumorsbearingIressa®-sensitivemutations,resistantsubclonescontaininganadditionalEGFRmutation,T790M,emergeinthepresenceofthedrug.IthasbeenshownexperimentallythattheT790Mmutationleadstohigh-levelfunctionalresistancetoIressa.InpatientswithtumorsbearingIressa®-sensitivemutations(eg.L858R,L861Q),resistantsubclonescontainingtheT790Mmutationemergeinthepresenceofthedrug. |