ConstitutivelyactiveNRF2signalingisassociatedwithradiationresistanceandpoorpatientoutcomeinseveral cancer types, includingoral squamous cell carcinoma (OSCC). NRF2 is a transcriptionfactor which drives the phaseIIantioxidantgeneexpressionprogram.Incancer,NRF2isfrequentlymutatedtobecomeconstitutively active, resulting in protection from oxidative and metabolic stress, thereby driving radioresistance. The establishedroleofNRF2inpromotingradioresistancemakesitanattractivedrugtargettotreatcancerpatients. OurgroupgeneratedthefirstclinicallyrelevantNRF2mutant(Nrf2E79Q)GEMMtoevaluatetheroleofNRF2in cancer initiation, progression and therapeutic resistance. My preliminary data show that mouse embryonic fibroblasts (MEFs) derived from our Nrf2E79Q GEMM have increased cell viability and proliferation following radiationtreatmentcomparedtothosewithwild-typeNRF2.Thesefindingsareconsistentwiththeliteratureand demonstrate that NRF2 protects cells from oxidative stress and radiation. Through genetic crossing, we have isolated NRF2 expression to the oral cavity and will induce OSCC by treating the mice with a chemical carcinogen. For my thesisproject, I will study therole of NRF2 in OSCC in vivo and in vitrousing tumor cells derived from our model, analyzing cell viability, cell proliferation, and gene expression differences between Nrf2E79Qandwild-typeuponradiationtreatment.IhypothesizethatNRF2promotesresistancetoradiation in oral squamous cell carcinoma and inhibiting NRF2 will mitigate this resistance. Despite extensive evidence of a negative impact of NRF2 activity on clinical outcome, there remains no FDA approved NRF2 inhibitors.Asatranscriptionfactor,NRF2isinherentlydifficulttodirectlytarget.Therefore,wesoughttoidentify druggabletargets?specificallykinases?thatregulateNRF2.Tothisend,weperformedahigh-throughputlive cell imaging chemical screen using the Published Kinase Inhibitor Set (PKIS). I have validated numerous hits fromthescreenasNRF2inhibitors,includingcompoundswithstrongselectivitytomultiplePI3Ks.Inadditionto studying the role of NRF2 activation in oral keratinocytes and OSCC, my thesis work will also test the effectivenessoftheseinhibitorsinsensitizingNrf2E79QOSCCcellstoradiation.Further,toempowertranslational relevance,IwillcreatehumanisogeniccelllineswithaNrf2E79QalleleusingCRISPRtostudywhetherinhibiting NRF2decreasesradioprotectioninahumanOSCC.Validationoftheeffectivenessofthesekinaseinhibitorswill bring the field a step closer to targeting NRF2 in cancer and ultimately improve patient outcomes. The work prosedinthisgrantandmylargerthesiswillprovidemewithextensiveandstrongtraininginnewtechniquesas wellasintheconceptsofmousemodeling,treatmentresistance,radiationbiology,andtargetedtherapies.
The NRF2 transcription factor promotes resistance to radiation therapy in cancer, leading to poor patient outcome.Abetterunderstandingofresistancemechanismsiscrucialtoimprovingtreatmentsforpatients.This proposed project will define the role of constitutively active NRF2 in radioresistance in oral squamous cell carcinoma(OSCC)andwillidentifyregulatorymechanismsandpharmacologicinhibitorsofNRF2.
