Objective:Cancercellradioresistanceisastumblingblockinradiationtherapy.TheactivityinthenuclearfactorkappaB(NFκB)pathwaycorrelateswithanti-apoptoticmechanismsandincreasedradioresistance.TheIKKcomplexplaysamajorroleinNFκBactivationuponnumeroussignals.Inthisstudy,weexaminedtheinteractionbetweenionizingradiation(IR)anddifferentmembersoftheIKK-NFκBpathway,aswellasupstreamactivators,RAF1,ERK,andAKT1.Methods:Theeffectof4GyofIRontheexpressionoftheRAF1-ERK-IKK-NFκBpathwaywasexaminedinA549andH1299lungcancercelllinesusingWesternblotanalysisandconfocalmicroscopy.WeexaminedchangesinradiationsensitivityusinggenesilencingorpharmacologicalinhibitorsofERKandIKKβ.Results:IKKα,IKKγ,andIκBαincreaseduponexposuretoIR,therebyaffectingnuclearlevelsofNFκB(phospho-p65).ERKinhibitionorsiRNA-mediateddown-regulationofRAF1suppressedthepost-irradiationsurvivaloftheexaminedlungcancercelllines.AsimilareffectwasdetectedonsurvivaluponsilencingIKKα/IKKγorinhibitingIKKβ.Conclusions:ExposureoflungcancercellstoIRresultsinNFκBactivationviaIKK.ThegeneticorpharmacologicalblockageoftheRAF1-ERK-IKK-NFκBpathwaysensitizescellstotherapeuticdosesofradiation.Therefore,theIKKpathwayisapromisingtargetfortherapeuticinterventionincombinationwithradiotherapy.
