Pancreatic cancer is the 4th leading cause of death by cancer in the United States and remains virtually incurable (1, 2). Despite advances in our understanding of the mechanisms contributing to development of pancreatic cancer, current therapies remain largely ineffective (3,4). Thus, novel therapies rely on identification and characterization of new molecular targets that contribute to pancreatic carcinogenesis. Hedgehog (HH) proteins are a highly conserved family of secreted intercellular molecules that signal across the plasma membrane to activate GLI transcription factors (GLI 1, 2 and 3), essential effectors of their cellular functions (5-7). Alterations in key components of HH pathway can lead to tumor development in several different tissues (8-10). Activation of the HH pathway plays a key role in pancreatic carcinogenesis. Specifically, sustained HH signaling is required for the growth and survival of pancreatic tumors (11,12). Most studies to date have been performed in animal models; however, to our knowledge, the current proposal represents one of the first to investigate specific molecular mechanisms of action of HH at the cellular and molecular level. Our preliminary data shows that HH increases the survival of pancreatic cancer cells through activation of specific anti-apoptotic cascade including Bcl-2, Bfl-1/A1, and 4-1BB. Initial evaluation of this putative mechanism revealed that the HH requires intact GLI1 and GLI2 transcriptional activity to activate this survival response. Therefore, to further elucidate this issue, we will test the central hypothesis that the Hedgehog pathway regulates cell survival by modulating anti-apoptotic cascades in pancreatic cancer cells via GLI-mediated transcriptional control of key mediators of cell death. To address this hypothesis we propose two aims in which we will 1) characterize the mechanisms by which HH pathway regulates survival of pancreatic cancer cells, and 2) determine the translational significance of targeting this survival pathway as a therapeutic tool to inhibit pancreatic carcinogenesis. Our preliminary data support both our hypotheses and the feasibility of the study. Thus, the knowledge derived from these studies will provide both mechanistic insight into the contribution of the HH pathway to the pathogenesis of pancreatic cancer and will serve as foundation for development of new therapeutic approaches. These aspects make this proposal mechanistic, hypothesis-driven, and potentially translational in nature. ? ? ? ?
