LY6D identifies persistent stem-like cells driving pancreatic tumourigenesis

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy characterised by remarkable cellular heterogeneity, which emerges early from the interplay of oncogenic KRAS signalling and inflammatory injury. However, the transcriptional, metabolic and functional properties of these pre-malignant cell states that initiate and drive PDAC progression remain elusive. OBJECTIVE: This study aimed to identify and functionally characterise the critical premalignant cell states that arise from this heterogeneity, to define novel biomarkers and targets for early intervention. DESIGN: Public and in-house scRNA-seq data of pancreatic tumour models were analysed to identify key subpopulations in early cellular heterogeneity. Genetic perturbation in KrasG12D-driven models was performed to assess functional impact. Mechanistic studies used TurboID proximity proteomics, epigenetic profiling and metabolic assays. Clinical relevance was validated in human PDAC cohorts. RESULTS: We identified LY6D as a marker of a distinct, gastric-like cell state that emerges early and persists throughout tumourigenesis. The LY6D+ population exhibits conserved stemness and a unique, pan-stage dependency on oxidative phosphorylation (OXPHOS). Genetic ablation of Ly6d specifically impaired the gastric lineage and delayed tumourigenesis, while its overexpression enhanced tumourigenic and metastatic potential. Mechanistically, the glycosylphosphatidylinositol (GPI)-anchored LY6D protein s...