Caspase-3 activation during apoptosis can trigger caspase-3 cleavage of gasdermin E (GSDME). The gasdermins (GSDM) are afamilyofproteins, whose cleavage activates inflammatorydeath, calledpyroptosis. N-terminalGSDMfragmentsformporesinthecellmembranethatcauserapidcelldeathinwhichthecellswells, activatesandreleasesinflammatorycytokinesandotherinflammatorymediators,andeventuallybursts.GSDME cleavageconvertsnoninflammatoryapoptoticdeathtomorerapidinflammatorypyroptoticdeath.GSDMEisnot expressedinmostcancercelllines,isepigeneticallyinactivatedingastric,colorectalandbreastcancer,relative tonormal tissue,and mutated in someothers. GSDME expression suppresses colony formation ingastric and colorectal cancer and invasivity of breast cancer. Worse 5-year survival and an increase in lymph node metastases areassociated with reduced GSDME in breast cancer. Moreover, lack ofGSDMEpromotesdrug resistanceinmelanomaandlungcancercelllines.WehypothesizethatGSDMEactslikeatumorsuppressor, thatsometumorcellsavoidpyroptosisbydownregulatingormutatingGSDMEandthattheswitchfrom apoptosis to pyroptosis profoundly affects tumor cell survival, anti-tumor immunity and response to chemotherapy and radiation. In preliminary data, cancer-associated GSDME mutations are shown to be primarily loss of function mutations. Gsdme knockout in cancer lines promoted tumor growth while ectopic GSDMEexpressionstronglyinhibitedtumorgrowthinimmunecompetentmice.Thetumorsuppressiveroleof GSDME was lost in immunodeficient NOD.scid.Il2rg-/- (NSG) and Prf1-/- mice deficient in perforin and strongly inhibitedbyNKorCD8Tcelldepletion.GSMDEexpressionbythetumorincreasedinfiltrating,functionalCD8 T cells and NK cells. Based on these data, we hypothesize that GSDME suppresses tumor growth by recruiting and activating anti-tumor killer lymphocytes. We also found that granzymes B and M, death- inducingproteasesofkillerlymphocytes,directlycleaveGSDMEduringkillercellattacktoactivatepyroptosisin a caspase-independent manner, which is amplified by caspase activation. We also hypothesize that direct granzyme cleavage of GSDME in cancer cells triggers pyroptosis and enhances their anti-tumor immunity.Killerlymphocytemediateddeathhaspreviouslybeenthoughttobenon-inflammatory.Ourgoalis to test these hypotheses and develop mechanistic insights to understand whether and how suppression of GSDME activation ofpyroptosis in cancer cells impactsoncogenesis, drug sensitivity and protective immunity. OurspecificaimsaretoinvestigatetheeffectofGSDMEmutationandexpressiononGSDMEactivation,lipid binding, oligomerization and pore formation, on whether cell death by apoptotic stimuli or killer cells is inflammatoryandimmunogenic,andwhetherandhowGSDMEaffectstumorgrowth,immunityandresponses totherapyinvitroandintransplantedmousetumormodels.