Abstract 4232: Exploring chemotherapy resistance in pancreatic cancer: Insights from a 3D organoid model

Abstract Pancreatic cancer is marked by a dismal prognosis, with a 5-year survival rate at approximately 10%. A key contributor to its lethality is the development of chemotherapy resistance, followed by early metastasis. However, studies elucidating the mechanisms behind chemotherapy resistance in pancreatic cancer are limited. Previous research has relied on 2D cell line models, which present limitations, such as uniform cell types that fail to capture tumor heterogeneity and an inaccurate representation of clinical realities, wherein resistance often develops gradually rather than through continuous exposure to high drug concentrations. In this study, we developed a more sophisticated organoid model of chemotherapy resistance. Six organoids from three patients were matched to study chemotherapy resistance in a personalized context. Comprehensive whole-exome sequencing and transcriptomic analyses were performed, along with an examination of chemotherapy resistance protein expression and EMT-related markers. Notably, differential expression levels of CK19 and Vimentin were observed between samples. Our analysis also focused on the expression of the ATP-Binding Cassette Subfamily G Member 2 (ABCG2) gene in chemoresistant organoids. Western blot analysis indicated a significant increase in ABCG2 expression in these organoids compared to controls. According to the Moffitt RNA signature, the primary and corresponding chemoresistant organoids retained their molecular subtype classifications both before and after developing chemoresistance. Gene set enrichment analysis uncovered significant upregulation of pathways related to DNA repair and cell cycle regulation, particularly the G2M checkpoint, in chemoresistant organoids. Furthermore, gene ontology functional analysis suggested a notable overrepresentation of activities related to amino acid transmembrane transport and extracellular matrix constituents, underscoring their potential role in the chemoresistance phenotype. Citation Format: Hee Seung Lee. Exploring chemotherapy resistance in pancreatic cancer: Insights from a 3D organoid model abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 4232.