Identifying Metabolic Dependencies of Pancreatic Cancers

项目总结:

Project Summary: The focus of my research has been on the study of pancreatic ductal adenocarcinoma (PDAC). This is a deadly tumor that is predicted by 2020 to be the second leading cause of death in the U.S. The disease is typically detected late in its course and unfortunately has proven to be highly treatment refractory to most therapeutic approaches. Over the past decade, our group has been focused on understanding how PDAC rewire their metabolism to support a high proliferative rate and cell survival in a nutrient poor, austere tumor microenvironment. We have used novel mouse models to understand how oncogenic Kras, the signature genetic mutation in PDAC, orchestrates metabolic reprogramming of these tumors towards a more anabolic state. In fact, one of the critical ways that this oncogene supports pancreatic cancer growth is through its role in tumor metabolism. Through further analysis of carbon source utilization in PDAC, we identified a novel pathway that is critical for PDAC redox balance through the production of NADPH. This pathway utilizes glutamine carbon and portions of the malate-aspartate shuttle ultimately ending with malic enzyme conversion of malate to NADPH and pyruvate. Disruption at any node of this metabolic pathway results in redox imbalance and decreased growth. One of the major themes that emerged from our work is that PDAC have an amazing metabolic plasticity. This is likely an important adaptation to flourish in an environment where fuel sources and oxygen are rate limiting and rapidly shifting. Understanding these adaptations will be essential in order to target metabolic vulnerabilities for therapeutic gain. Indeed, we have shown that that these tumors can: 1) rapidly reprogram their metabolic pathways in response to fuel source limitations, 2) use lysosomal scavenging pathways to provide necessary metabolic intermediates, and 3) cooperate with stromal cells through novel metabolic interactions. However, the integration of these metabolic adaptations and how this influences key metabolic dependencies of PDAC in vivo is not yet known and will be critical to understand in order to develop effective therapeutic approaches. Here, we will take a comprehensive approach to answer these key questions. We will use sophisticated syngeneic models of pancreatic cancer to comprehensively assess metabolic dependencies using a custom designed murine CRISPR metabolism library combined with metabolic tracer studies. We will use co-culture systems to identify metabolic cross-talk between tumor cells and the multiple other cell types in the tumor micro-environment (immunocytes, neurons, fibroblast populations). Using in vivo models, we will dissect nutrient scavenging pathways and identify how these nutrients are utilized and potentially shared between cell populations. Lastly, we will utilize the knowledge gained from these studies to develop the most robust metabolic targets which will be tested in vivo using genetic and pharmacologic approaches.