Multimodal transcriptomics reveal myCAF-derived collagen signaling associated with impaired NK-cell cytotoxicity and immune exclusion in pancreatic cancer

BACKGROUND: Despite years of research, pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest cancers. A highly fibrotic, immunosuppressive microenvironment poses a significant barrier to effective immunotherapy. As key innate immune effectors of antitumor immunity, the functional status of natural killer (NK) cells within this environment remains poorly understood. This study aims to explore the role of stromal-immune interactions, particularly myofibroblastic cancer-associated fibroblasts (myCAFs) and NK cells, in shaping immune dysfunction in PDAC. METHODS: We integrated spatial, single-cell and bulk transcriptomic analyses to characterize NK-cell heterogeneity and its cellular and molecular regulation in PDAC. CellChat-based communication analysis, spatial co-localization, and multiplex immunofluorescence were utilized to identify regulatory interactions and validate spatial associations. RESULTS: A tumor-associated NK (TaNK) subset with impaired cytotoxicity was identified. myCAFs strongly interacted with TaNK cells through collagen signaling. Within ligand-receptor pairs, COL1A2-CD44 and COL1A1-LAIR1 served as dominant mediators linking stromal remodeling to impaired NK cell function. Spatial and histological validation confirmed their co-localization, while tumors co-enriched with myCAFs and TaNKs exhibited immune exclusion and poor response to immunotherapy. CONCLUSIONS: Our study demonstrates that collagen signaling from myCAFs impairs NK-cell cytotoxicity and promotes immune exclusion in PDAC. These findings advance the understanding of stromal-immune mechanisms underlying immunotherapy resistance and highlight that targeting the myCAF-NK axis may help improve the response to immunotherapy in PDAC.