Project Abstract Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease with a dismal survival rate at just 10%, largely because most patients are diagnosed after the cancer has spread beyond the pancreas. PDAC is thought to arise from two types of noninvasive precancerous lesions, namely, pancreatic intraepithelial neoplasia (PanINs), and intraductal papillary mucinous neoplasms (IPMN), that develop in the ductal epithelium of the pancreas. Here, IPMNs are large cystic neoplasms that are incidentally detected at increasing frequencies through abdominal imaging. Comprehensive genomic analyses indicate that activating mutations in KRAS, GNAS, and PI3KCA are associated with IPMN pathogenesis. Although genetically engineered mouse models (GEMMs) have provided some insights into the development of IPMN, how IPMNs arise in humans in the context of mutations that are exclusively found in IPMN lesions (GNAS and PIK3CA) and what cooperating events promote progression to carcinoma is not understood. To address this question, we have developed a robust platform to generate ductal and acini organoids from human embryonic stem cell (hESC)-derived pancreatic progenitor cells. Using human exocrine pancreas, I have found that expression of GNASR201C in human ductal organoids recapitulates several features of IPMN including lumen expansion, and secretion of mucins such as MUC2. This study sets out to test the hypothesis that oncogenic GNAS promotes cell proliferation through PKA-independent mechanisms in ductal cells and cooperates with other genetic events to promote initiation and progression of IPMN lesions in vivo. Using a combination of cell biology, proteomics, and orthotopic transplantation approaches, this proposal aims to identify mechanisms through which oncogenic GNAS differentially regulates cell proliferation in ductal and acini pancreatic organoids (Aim1); and explore additional genetic events through which oncogenic GNAS promotes formation of IPMN and IPMN-derived PDAC in the context of a physiologically accurate tissue environment (Aim 2 and 3). The expected results will provide insights into the cell of origin for IPMN lesions; identify mechanisms by which GNAS promotes early lesions; and establish models of IPMN- derived PDAC, which may be exploited therapeutically in the long term to treat a broad range of IPMN-associated tumors. The K22 award will allow participation in laboratory management, mentorship and grant writing workshops, and enrolment in didactic courses, that will provide me with the necessary knowledge, resources and training to (a) understand principles of omics research; (b) model cancer in mice; and (c) apply for additional funding (R01) opportunities. Together with the support of my collaborators and establishment of an advisory committee after obtaining a faculty position, my overall research, training and career development will help me establish a unique niche in pancreatic cancer research as an independent investigator.

Project Narrative In 10% of elderly patients, pancreatic ductal adenocarcinoma (PDAC) originates from mucin-producing cystic precancerous lesions called intraductal papillary mucinous neoplasms (IPMNs). Activating mutations in GNAS(R201C) are thought to drive IPMN-derived PDAC, but the cell of origin for IPMN initiation is not known. This proposal aims to take advantage of human stem cell-derived pancreatic ductal and acini organoids to understand how oncogenic GNAS supports initiation and progression of IPMNs in pancreatic cancer.