Glycomics and Glycoproteomics Reveal Distinct Oligomannose Carriers Across Bladder Cancer Stages.

Aberrant glycosylation is a hallmark of cancer, offering opportunities to enhance clinical decision-making and enable precise targeting of cancer cells. Nevertheless, alterations in the bladder urothelial carcinoma (BLCA) N-glycome remain poorly characterized. Here, we used in situ N-deglycosylation and mass spectrometry, revealing a marked enrichment of oligomannose-type N-glycans in non-invasive Ta tumors, which diminished with disease progression. A complementary analysis of The Cancer Genome Atlas (TCGA) transcriptomic data revealed downregulation of the key mannosidases in BLCA, suggesting a mechanistic basis for oligomannose accumulation, though this requires further validation. Then, targeted glycoproteomic profiling identified potential stage-specific carriers of oligomannoses. Exploratory functional annotation suggests stage-dependent differences among detected glycoproteins, ranging from metabolic regulation in Ta tumors to oxidative stress adaptation in muscle-invasive disease, highlighting glycosylation's contribution to tumor progression. Furthermore, myeloperoxidase (MPO) was enriched in more aggressive stages. Spatial validation confirmed MPO overexpression in tumor-infiltrating immune cells and its correlation with oligomannose content. Importantly, high MPO expression combined with low mannosidase levels was linked to poor survival, suggesting biological relevance. This study suggests a dynamic, stage-specific N-glycome in BLCA and identifies oligomannose-bearing glycoproteins as exploratory leads for biomarker and therapeutic target discovery, providing a N-glycomic resource for further investigation towards glycan-based precision oncology.