PROJECT SUMMARY Cancer cells are the organizers of their surroundings and create a tumor microenvironment (TME) favoring cell division even when oxygen and nutrients are limiting. An extreme example is pancreatic ductal adenocarcinoma (PDAC) which establishes a metabolically hostile ecosystem characterized by a hypo-vascular, severely hypoxic, and nutrient deprived stroma. Clinical trials targeting components of the PDAC stroma have not improved overall survival in unselected cohorts. Thus, while opportunities for targeting the PDAC TME exist, the development of anti-stromal therapies will require a better understanding of inter- and intra-tumoral heterogeneity. Our labs have studied two features of the PDAC stroma: the vasculature and CAFs. By analyzing multiple human datasets, and mouse models, we found that a significant portion of human PDACs (~10%) are hyper-vascular. In murine models, hyper-vascularity is associated with increased sensitivity to angiogenesis inhibitors. In addition, our preliminary studies have shown that in the more typical hypo-vascular tumors, hypoxia renders PDAC tumor cells incapable of synthesizing unsaturated fatty acids (uFAs), and therefore critically dependent upon lipids supplied by neighboring CAFs for their survival. Based on these data, we hypothesize that cancer- associated micro-vasculature and lipid secreting fibroblasts represent under-exploited, clinically relevant targets within the PDAC stroma. Here, we propose an innovative approach to delineate the cellular mechanisms by which tumor cells build and maintain critical metabolic “supply chains” and how regional differences within tumors influence nutrient utilization and vascular intravasation. Our proposal addresses both basic and translational questions and utilizes human tissue resources, implantable and genetically engineered mouse models, platforms to assess stromal geography and metabolic features, and cancer-on-chip techniques for ex vivo modeling. Our ultimate goal is to understand and manipulate the major sources from which PDAC cells derive essential nutrients (especially vital uFAs) – focusing on micro-vessels and fibroblasts. Aim 1. Determine the causes and consequences of vascular heterogeneity in PDAC Aim 2. Delineate molecular mechanisms and therapeutic opportunities underlying stromal support of lipid metabolism in PDAC