Quantitative Localized Analysis Reveals Distinct Exosomal Protein-Specific Glycosignatures: Implications in Cancer Cell Subtyping, Exosome Biogenesis, and Function
-acetylgalactosamine (Gal/GalNAc). In combination with sialic acid (Sia) cleavage manipulation for the exposure of originally capped Gal/GalNAc, QLA has revealed distinct MUC1-specific sialylation capping ratios for MCF-7 and MDA-MB-231 exosomes, as well as when compared to parent cells. These findings suggest a useful noninvasive indicator for subtyping cancer cells and exosome secretion as a likely venue for the preservation of cellular compositional and functional integrity. The QLA method also permits dynamic monitoring of changes in the exosomal MUC1-specific sialylation capping ratio, enabling the distinction of biogenesis pathways of exosomes.