Abstract 2581: Establishing a multi-omic spatial ECM proteome and N-glycome of pancreatic ductal adenocarcinoma tissues

Abstract Pancreatic Ductal Adenocarcinoma (PDAC), one of the leading causes of cancer related mortality nationwide, is characterized by an extensive desmoplastic stromal reaction and an altered N-glycome. Stromal collagens serve to modulate the immune microenvironment, limit nutrient and oxygen diffusion, influence chemotherapy resistance, and promote tumor progression and metastasis. Dysregulated cancer cell N-glycosylation also promotes immune evasion and neoplastic spread. Despite their important roles in cancer pathogenesis, little is known about the spatial localization and organization of the various stromal collagens, other extracellular matrix proteins, and N-glycans within the PDAC tumor microenvironment. This study utilized Matrix Assisted Laser Desorption Ionization-Mass Spectrometry Imaging (MALDI-MSI) with Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) to characterize the extracellular matrix proteome and glycome of 10 primary PDAC patient tumors in collaboration with the Washington University SPORE in Pancreatic Cancer at the Siteman Cancer Center. Following PNGaseF glycosidase digestion of PDAC tissues, 214 released N-glycans and their spatial distributions were detected by MALDI-MSI. These tissues were then digested with Collagenase III for detection and localization via peptide MALDI-MSI. Tissues were scraped from the slide and further digested with Collagenase III in solution for peptide ID analysis by LC-MS/MS, with 31 identified peptides confirmed and matched to MALDI peaks. Spatially, both ECM peptides and N-glycans uniquely colocalize with various histopathologic features according to multiplex immunohistochemistry. N-glycans with bisecting N-acetylglucosamine structures associated specifically with the invasive tumor front and clusters of immune cell infiltrate, while distinct collagen species encased tumor cell regions and formed stromal nests surrounding immune cells. The degree of proline hydroxylation and other post translational modifications also varied across confirmed ECM peptides and may impact stability and deposition. From this analysis we may begin to link the N-glycome and ECM proteome of PDAC with patient survival, treatment response and other clinical variables. Citation Format: Caroline G. Kittrell, Jade Macdonald, Blake Sells, Lyndsay E. Young, David DeNardo, Peggi M. Angel, Richard R. Drake. Establishing a multi-omic spatial ECM proteome and N-glycome of pancreatic ductal adenocarcinoma tissues [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2581.