Abstract Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies, primarily due to its detection at advanced stages, with therapy resistance being the second major cause, leading to limited treatment options. It is well established that pancreatic differentiation is controlled by Notch during organogenesis, and its reactivation is seen in pancreatic tumorigenesis. The regulation of Notch signaling and its relationship with pancreatic exocrine and endocrine cells in pancreatic cancer is still unclear. Therefore, this study was designed to investigate the role of Notch in PDAC initiation and progression with respect to different cells of origin, along with a significant focus on understanding the potential of these cells to behave like cancer stem cells. The two different types of PDAC cells, derived from primary mouse tumors with Kras mutation and p53 deletion, were tested for their sensitivity to various pharmacological inhibitors. These cells originated from Lunatic Fringe (Lfng)-expressing centroacinar cells (CAC) and Mist1-expressing acinar cells. The subsets of Lfng+ tumor cells in these two types of PDAC were sorted for the tests in comparison with their Lfng- counterparts. The protein expression of Notch receptors was analyzed along with their downstream targets. The cells isolated from mice harboring PanIN lesions (not yet developed into PDAC) were examined for their organoid-forming capability to trace which lineage of PDAC cells carries the stem-like properties. Finally, the organoids were analyzed for various markers of pancreatic progenitors and stem-like characteristics to gain insight into the subset of pancreatic cells involved in the initiation of PDAC. It was found that the PDAC cells derived CAC population has an inherent property of behaving as cancer stem-like cells. These cells were highly resistant to the inhibitory effects of the chemotherapy drug gemcitabine compared to acinar-derived PDAC cells. However, they were uniquely sensitive to a gamma-secretase inhibitor, which blocks Notch activation. High expression of Notch3 and Hes1 was predominantly found in the CAC-derived PDAC cells, along with the high efficiency in forming 3D organoids, even at the early stage of tumor initiation. The organoids were found to co-express ductal (CK19) and acinar (Amylase) cell markers, containing cells expressing the pancreatic progenitor marker (Pdx1), stem cell marker (Aldh1a1), and Vimentin-expressing cells, which represent a more aggressive and metastatic subpopulation. These findings hold significant potential in unraveling treatment options and screening patients based on the subtype of the PDAC population. The full potential of GSI needs to be explored for its use as a treatment option alongside other available chemotherapy drugs. Targeting Lfng-dependent Notch signaling may offer an option for treating patients with CAC-derived PDAC. Citation Format: SHIFA KHAN, Wen-Cheng Chung, Charles D. Moore, Keli Xu. Uncovering a pancreatic ductal adenocarcinoma sub-population with stemness and unique therapeutic response abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2206.
KHAN et al. (Fri,) studied this question.