Abstract 787: RE1-silencing transcription factor (REST) controls neuroendocrine gene programs in pancreatic ductal adenocarcinoma

Abstract

Abstract Neuroendocrine (NE) differentiation features contribute to intratumoral heterogeneity and aggressive biology in a subset of pancreatic ductal adenocarcinoma (PDAC) tumors associated with poor disease outcome. We recently showed that treating pancreatic cancer cells with gemcitabine, a standard-of-care chemotherapy for PDAC, increases expression of NE markers, suggesting that ductal to neuroendocrine lineage plasticity could play a role in drug resistance. NE features in prostate cancer have been previously associated with loss of the neuronal gene repressor RE1-Silencing Transcription Factor (REST); in the present study, we explore a potential role of REST in regulating NE differentiation in PDAC. Our experiments show that loss of REST in PDAC cells increases NE gene expression, gemcitabine resistance, and colony formation. RNA sequencing data from gemcitabine-treated PDAC cells were enriched for REST target genes, suggesting gemcitabine relieves REST-mediated repression. Chromatin immunoprecipitation experiments corroborated this by demonstrating that gemcitabine reduces REST binding to the NE genes SYP and SNAP25. In addition, single cell ATAC sequencing also uncovered a heterogeneous response to gemcitabine treatment, revealing two gemcitabine-driven cell states with differing REST motif accessibility. Our study indicates that REST controls NE gene programs in PDAC and that loss of REST promotes gemcitabine resistance and oncogenic growth. Mirroring the heterogeneity of PDAC tumors, a subset of PDAC cells treated with gemcitabine have reduced REST motif accessibility, which may reflect a therapy resistant NE-like subpopulation. Citation Format: Kevin Alexander MacPherson, Meghan M. Joly, Brittany Allen-Petersen, Carl Pelz, Mary C. Thoma, Kristof Torkenczy, Andrew Adey, Daniel Liefwalker, Patrick J. Worth, Rosalie C. Sears. RE1-silencing transcription factor (REST) controls neuroendocrine gene programs in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 787.