Compressive Forces Shape Tumor–Macrophage Interactions Associated with Immunosuppression in Pancreatic Cancer

Abstract Purpose Pancreatic ductal adenocarcinoma (PDAC) develops within a biomechanically abnormal tumor microenvironment, characterized by a dense stroma and elevated compressive forces. While extracellular matrix stiffness has been extensively studied, the impact of compressive forces on immune regulation and tumor–immune interactions remains poorly understood. Methods We integrated two complementary bioengineered compression models, a 2D transmembrane pressure device and confined 3D spheroids, with bulk transcriptomic and Liquid Chromatography–Mass Spectrometry (LC-MS)–based exometabolomic profiling to examine how mechanical compression shapes macrophage behaviour and tumor–immune crosstalk. Controlled compressive stress (0–8 mmHg) was applied to macrophages, tumor cells, and tumor–macrophage cocultures, followed by pathway analysis, functional assays, and multi-omic integration. Results Mechanical compression activated conserved mechanotransduction pathways in macrophages, including PI3K/Akt and MAPK/SAPK signaling, and induced transcriptional programs associated with inflammatory activation consistent with an M1-like macrophage phenotype and cytoskeletal remodelling. In parallel, compressed tumor cells adopted an immunomodulatory state marked by increased expression of immunosuppressive cytokines and macrophage checkpoint signals. When tumor cells and macrophages were simultaneously exposed to compression, functional assays revealed a shift of macrophages toward immunosuppressive phenotypes. Bulk RNA sequencing identified cell-type–specific transcriptional responses converging on metabolic pathways, while LC-MS exometabolomics revealed compression-dependent enrichment of extracellular nucleotide metabolites in tumor–macrophage cocultures. Conclusions These findings identify compressive stress as a critical regulator of immune suppression and tumor–immune metabolic coupling in PDAC, highlighting mechanical forces as important drivers of immune dysfunction in mechanically constrained tumors.