Multi-Omics and Single-Cell Dissection Reveals EXT1 as a Glycosylation-Linked Therapeutic Target in Cancer

<b>Background:</b> Glycosylation and inflammation are pivotal in tumor progression, yet the specific glycosyltransferases bridging these processes remain poorly defined. This study investigated Exostosin-1 (EXT1), a key enzyme in heparan sulfate (HS) biosynthesis, as a mechanistic bridge connecting inflammation, stromal remodeling, and immune evasion-driven cancers. <b>Methods:</b> We used a multi-omics approach including Least Absolute Shrinkage and Selection Operator (LASSO) Cox regression on The Cancer Genome Atlas (TCGA) pan-cancer cohorts, transcriptomics, survival, single-cell RNA sequencing (scRNA-seq), DNA methylation profiling, pathway enrichment analysis (MetaCore), molecular docking, and immunohistochemistry (IHC) on pancreatic adenocarcinoma (PAAD) and lung adenocarcinoma (LUAD) tissue microarrays. <b>Results:</b> EXT1 was identified as one of only two genes overlapping inflammation- and glycosylation-related gene sets, strongly associated with poor overall survival (OS), disease-specific survival (DSS), and progression-free survival (PFS) across cancers, particularly in PAAD and LUAD. Pan-cancer profiling revealed broad EXT1 upregulation. ScRNA-seq localizedEXT1to stromal cells (pancreatic stellate cells, fibroblasts) and epithelial cells co-expressed with immune checkpoint markers. EXT1 promoter hypomethylation correlated with high expression and poor survival. Enrichment analysis of EXT1-correlated genes highlighted activation of critical pro-tumorigenic pathways, including transforming growth factor-β (TGF-β), lysophosphatidic acid (LPA), epidermal growth factor receptor-phosphoinositide 3-kinase-AKT-mitogen-activated protein kinase (EGFR-PI3K-AKT-MAPK), integrin-focal adhesion kinase-Rho GTPase (integrin-FAK-Rho), and epithelial-mesenchymal transition (EMT) pathways. IHC validated stage-dependent EXT1 overexpression in both PAAD and LUAD. <b>Conclusion:</b> This multi-omics study identifies EXT1 as a novel link between glycosylation and inflammation. It functions as a driver of stromal activation, immune checkpoint engagement, and tumor progression. EXT1 represents a clinically relevant biomarker and a promising therapeutic target in inflammation-driven cancers like PAAD and LUAD.