DESCRIPTION (provided by the applicant) Colorectal cancer is second leading cause of cancer-related deathsamong men and women in the United States with metastasis to secondary organs (e.g. liver) playing a majorrole in patient mortality. Patients with metastatic or stage IV colon cancer display a 5 year survival rate of only11%. Recent clinical and gene profiling studies indicate that a loss of Absent in Melanoma 2 (AIM2) expressionin colon tumors is highly correlated with stage IV colon cancer and reduced patient survival. AIM2 is a cytosolicinnate immune sensor that forms a multi-protein complex termed the inflammasome following binding ofdouble-stranded DNA. I have recently reported that AIM2 suppresses colon cancer development independentlyof its inflammasome function by limiting the uncontrolled replication of colonic epithelial cells by acting as acheckpoint of Akt-mediated survival. Mechanistically AIM2 suppresses Akt activity by targeting the PI3K familymember DNA-dependent protein kinase (DNA-PK). Although DNA-PK activation and expression is reportedlyelevated in colon tumors and DNA-PK promotes Akt activation cell survival and metastatic gene profiles thefunction of DNA-PK during colon cancer pathogenesis is largely understudied. In addition AIM2 has beensuggested to limit tumorigenesis by regulating the composition of the intestinal microbiota yet there is no directevidence for this and it is unknown if microbiota-derived DNA facilitates AIM2's tumor suppressor function orwhat AIM2-related factors are responsible for limiting tumorigenesis. In this proposal I will test thehypothesis that AIM2 restricts cancer initiation and metastasis by limiting Akt and DNA-PK activationin response to the microbiota using the following specific aims: 1) Determine the functional requirement ofDNA binding to AIM2 during the suppression of cancer-relevant pathways in vitro; 2) Assess the ability of AIM2to limit DNA-PK-mediated colon cancer development and metastasis in vivo; and 3) Elucidate the mechanismby which AIM2 responds to and regulates the intestinal microbiota to limit colon cancer. This proposal buildsupon my prior work that includes a strong background in cell signal transduction intestinal microbiome profilingand animal models of colon cancer initiation while working in the laboratory of Jenny P-Y Ting at theLineberger Comprehensive Cancer Center at the University of North Carolina at Chapel Hill. With additionaltechnical assistance and core facility support from my collaborators this K22 award will provide critical trainingin in vitro primary colon organoid culture systems Crispr/Cas9 gene editing mouse models of spontaneoustumorigenesis and metastasis gene expression and signal transduction profiling of human cancer tissue andmanipulation of the microbiome to target cancer which are required to achieve my long-term goal of becomingan established tenured-track principle investigator in the area of Cancer Immunology. The proposed researchwill lead to a greater understanding of how the tumor suppressor AIM2 limits tumorigenesis and may lead tothe development of novel therapeutics for the treatment of multiple cancers.