Ubiquitination‐Associated Ductal–Fibroblast Crosstalk Shapes Tumor Progression and Prognosis in Pancreatic Ductal Adenocarcinoma

Background: Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy characterized by a complex tumor microenvironment. Ubiquitination regulates key oncogenic processes and microenvironmental remodeling; however, its cell type-specific activity and spatial organization within the PDAC microenvironment remain poorly understood. Materials and Methods: Single-cell RNA sequencing, spatial transcriptomics, and bulk RNA-seq datasets of PDAC were integrated for multiomics analysis. Ubiquitination activity was quantified using gene-set scoring algorithms, followed by cell-communication and spatial interaction analyses. Prognostic models were constructed using bulk cohorts, and key findings were validated through gene-silencing functional assays. Results: Ubiquitination activity was significantly increased in PDAC tissues compared with adjacent normal tissues, with ductal epithelial cells and fibroblasts showing the most prominent elevation. High ubiquitination states were associated with enhanced ductal-fibroblast interactions and distinct spatial patterns linked to invasion-associated tumor regions. Integration of ubiquitination-associated gene signatures identified a robust prognostic model, highlighting an extracellular matrix-related factor consistently overexpressed in tumors and associated with poor survival. Functional assays demonstrated that suppression of this factor inhibited proliferation, migration, invasion, and survival of pancreatic cancer cells. Conclusion: Ubiquitination organizes ductal-fibroblast crosstalk within the PDAC microenvironment and links spatial tumor ecology with disease aggressiveness and patient prognosis. Targeting ubiquitination-associated microenvironmental programs may offer new strategies for prognostic stratification and therapeutic intervention.