PROJECT ABSTRACT Pancreatic adenocarcinoma (PDAC) is an almost uniformly fatal disease most often diagnosed after the development of metastases. The tumor suppressor gene, TP53, is the most commonly altered gene in human cancer and has been recognized as a genetic driver of PDAC in up to 75% of patients. While the functions of TP53 mutations within cancer cells continue to be studied, knowledge of its non-cell autonomous roles in the primary tumor microenvironment remain limited. The ultimate goal of our work is to exploit targets that arise in PDAC tumor cells or in the tumor microenvironment (TME) as a consequence of p53 mutation for translation into patient therapies. Recently, our laboratory discovered a cooperative signaling node between the top genetic PDAC drivers, oncogenic KRAS and mutant p53, engaged through interactive binding between mutant p53 and CREB1. This mutant p53/CREB1 complex subsequently activates multiple pro-metastatic transcriptional networks within tumor cells. Our preliminary data indicate that mutant p53/CREB1 GOF also drives non-cell autonomous functions through the activation of WNT/β-catenin signaling elements that direct cancer associated fibroblasts (CAFs) to curate the primary TME into pro-metastatic landscapes. We hypothesize that targeted disruption of the mutant p53/CREB1 complex is a viable opportunity to reverse cell- and non-cell autonomous functions of mutant p53 for therapeutic translation in PDAC. Accordingly, the objective of this grant proposal is to gain additional mechanistic insight into how p53 mutations in tumor cells drive pro-metastatic interactions with cancer associated fibroblasts and to test if disruption of the mutant p53/CREB1 complex subverts vitals steps in the metastatic cascade. Using genetically engineered mice and patient derived model systems, in aim 1 we will confirm essential elements of the mutant p53/CREB1-WNT/β-catenin signaling axis that consort with cancer associated fibroblasts to enhance migratory and invasive phenotypes. Moreover, we will test the efficacy of combined targeted approaches to disrupt multiple levels of the mutant p53/CREB1-WNT11 signaling axis to mitigate metastasis. In aim 2, we will clarify the role of the mutant p53/CREB1-WNT/β-catenin signaling axis in the curation of the fibrotic TME as it relates to chemoresistance and metastasis while testing its reversibility using genetic and pharmacologic strategies. In Aim 3, we will use human PDAC biospecimens and derived organoids to correlate our findings from Aims 1 and 2. The proposed research is significant because p53 mutations are present in 70 percent of PDAC patients and remain untargetable. As such, our approach to disrupt non-cell autonomous mutant p53 gain of function could expose new therapeutic vulnerabilities or inform rational combinatorial treatment strategies. The proposed research is innovative because we will study and modulate a novel mutant p53/CREB1-WNT/β-catenin signaling axis to undermine...