Abstract B18: Defining the role of chromatin remodeling complexes in pancreatic cancer stem cells

Pancreatic adenocarcinoma (PDAC) is a devastating disease characterized by high rates of metastasis and poor therapeutic response. It is currently the 4th leading cause of cancer-related deaths in developed countries, and despite efforts to improve therapy, the five-year survival rate remains at 9%. Therefore, it is critical to identify new programs that drive pancreatic cancer progression and therapeutic resistance. To define new cancer dependencies, work in the Reya lab has focused on characterizing stem cell programs that drive cancer initiation, propagation, and relapse. Previously published studies have demonstrated that the fate determinant Musashi2 (Msi2) functionally marks a drug-resistant stem population in pancreatic cancer. More recent work has revealed that this aggressive subpopulation is characterized by a unique transcriptional and epigenetic profile. Given the crucial role for epigenetic regulation in development, we hypothesized that differential expression of epigenetic regulatory factors could be responsible for the establishment or maintenance of a stem cell state in pancreatic cancer. To identify epigenetic factors critical to stem function, we used a functional shRNA screen to profile the impact of inhibition of stem-enriched candidate factors on 3D growth of Msi2+ pancreatic cancer cells in vitro. From this screen, we identified the gene Smarcd3 as a critical mediator of stem cell growth in pancreatic cancer. Smarcd3 encodes Baf60c, a component of the SWI/SNF nucleosome remodeling complex with known functions in cardiac and neural development. Though Smarcd3 function has not been studied in PDAC, the SWI/SNF complex at large is known to be dysregulated in pancreatic cancer. Preliminary studies have shown that Smarcd3 inhibition leads to reduced growth of both mouse and human pancreatic cancer cells in vitro and in vivo. Current studies are ongoing to 1) elucidate the mechanism by which Smarcd3 controls growth of pancreatic cancer cells through binding of developmental transcription factors, and 2) use genetically engineered mouse models of pancreatic cancer to define the role of Smarcd3 in pancreatic cancer initiation and progression. Citation Format: Lesley Paige Ferguson, Jovylyn Gatchalian, Nikki K. Lytle, Nirakar Rajbhandari, Kendall Chambers, Sonia Albini, Benoit Bruneau, Lorenzo Puri, Maike Sander, Andrew Lowy, Diana Hargreaves, Tannishtha Reya. Defining the role of chromatin remodeling complexes in pancreatic cancer stem cells [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr B18.