Abstract C059: Regulatory Elements of Pancreas Development License the Initiation of Pancreatic Ductal Adenocarcinoma

Abstract Mutations in DNA are a known cause of cancer. However, they become oncogenic only under specific cellular conditions and within certain tissue contexts. Tissue injury often leads to the aberrant activation of developmental pathways, eroding markers of cellular differentiation and giving rise to transient cellular states. These states resemble developmental progenitors, characterized by higher transcriptional plasticity. Oncogenes, particularly KRAS, co-opt cellular plasticity by acting on tissue-specific enhancers, preventing the resolution of acinar plasticity and maintaining the pancreas in a pro-inflammatory phase that progresses to cancer1, 2. However, the specific role of tissue-specific enhancers in pancreas regeneration and cancer initiation remains unexplored, and strategies to target these regenerative processes are yet to be developed. Our laboratory investigates non-mutational mechanisms of cancer, with a special interest in the intersection of developmental biology and cancer, aiming to elucidate the processes of cellular plasticity and cancer initiation. Recent studies have shown that acinar cells possess remarkable cellular plasticity, giving rise to a diverse population of cellular states in pancreas regeneration and cancer contexts3-5. We have discovered that the transcription factor Sox4 is necessary for the specification of tuft cells and gastric metaplasia found in chronic pancreatitis and in pancreatic intraepithelial lesions (PanINs). Moreover, we have shown that cellular plasticity has a non-cell autonomous protective effect; losing Sox4 and cellular heterogeneity in PanINs results in a fibrotic and immunosuppressive tumor microenvironment and disease progression. Our results demonstrated that targeting cellular plasticity accelerates or prevents cancer initiation through autonomous and non-autonomous cellular processes6. In this study, we leverage a comprehensive resource of ncRNAs transcribed from enhancer elements of pancreas development, together with their inferred target genes and correlations with clinical outcomes. We focused on an ncRNA associated with the risk of pancreatic cancer. To study its function, we developed two novel mouse strains for tissue-specific deletion, enabling precise manipulation and study of its role in the pancreas and other tissues. Our phenotypic analysis demonstrates that the ncRNA is activated following tissue injury and is essential for developing PanINs. Moreover, we show that it regulates cell-cell communication after tissue injury. This mechanism operates independently of cellular plasticity but significantly creates a pro-inflammatory environment that favors cancer development. Our results demonstrate that enhancer elements are actionable targets to regulate cell fate decisions in regeneration and cancer. Additionally, KRAS-induced cancer initiation depends on developmental regulatory elements, opening the window to develop prophylactic interventions to delay tumor onset. Citation Format: Luis Arnes. Regulatory Elements of Pancreas Development License the Initiation of Pancreatic Ductal Adenocarcinoma abstract. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84 (17 Suppl₂): Abstract nr C059.