Pancreatic ductal adenocarcinoma (PDAC) is highly lethal due to late detection and limited therapies. Early interception strategies are urgently needed. PDAC arises from oncogenic KRAS-driven acinar-to-ductal metaplasia (ADM) and pancreatic intraepithelial neoplasias (PanINs), progressing from low- (LG-PanINs) to high-grade (HG-PanINs) lesions. However, not all PanINs advance, and the cellular determinants of progression remain unclear. We hypothesised that a distinct subset of KRAS-mutant cells, termed Pancreatic Cancer Driver Cells (PCDCs), acquire stem-like features enabling lesion maintenance and progression.

Using the KC (Pdx-1CreER; LSL-KRasG12D/+; Rosa26 LSL-tdRFP) mouse model, a low dose of tamoxifen to activate KRasG12D in 20% of the pancreatic cells and a chronic pancreatitis protocol, we mimic early events in PDAC initiation. We applied single-cell (scRNAseq) and spatial transcriptomics (ST) to identify and study PCDCs and immunofluorescence staining (IF) and functional experiments to validate results.

Transcriptomic profiling revealed a distinct epithelial subpopulation present across all disease stages with enhanced stem and cancer stem cell signatures. These PCDCs overexpress genes associated with KRAS/MAPK signalling, cell adhesion, niche interaction and cellular stress resistance pathways, suggesting that PCDCs are uniquely equipped to survive oncogenic and inflammatory stress. Pseudotime analysis positioned PCDCs as progenitor-like, giving rise to differentiated epithelial states. Functionally, sphere formation assays confirmed that PCDCs possess enhanced self-renewal capacity compared to other PanIN cells. Organoid models derived from LG-PanIN, HG-PanIN and tumours demonstrated, via pharmacological inhibition, that PCDCs rely on active stress-resistance mechanisms for survival. Cell-cell interaction analysis identified Amyloid Precursor Protein (App)-Cd74 as the strongest predicted interaction between PCDCs and neighbouring epithelial cells. ST and IF confirmed this interaction and showed downstream activation of MAPK and NFκB pathways in Cd74 expressing cells. Inhibition of Cd74 using milatuzumab significantly reduced organoid growth, indicating that APP-CD74 signalling promotes early lesion progression. Importantly, ST and IF analyses confirmed that PCDCs are conserved in human PanINs and PDAC samples.

PCDCs are a stem-like population driving PanIN progression via stress resistance and pro-tumorigenic niche interactions. Targeting stress-adaptation programs and APP-CD74 signalling offers a promising early-interception strategy. These findings redefine PanIN progression as a cell state-dependent process, providing a framework to identify and eliminate true drivers of tumorigenesis.

This work is supported by Pancreatic Cancer UK.