N-glycan signatures of immunoglobulins-depleted serum proteins in colorectal cancer.

Protein glycosylation has been implicated in the pathogenesis of cancer, with colorectal cancer (CRC) strongly associated with serum N-glycosylation and IgG N-glycosylation. However, the N-glycosylation profile of non-immunoglobulin serum proteins (IgS-D) in CRC progression remains largely unexplored. Serum IgS-D was isolated using affinity chromatography, followed by the release of N-glycans, methylamidation, and MALDI-MS analysis. The potential of the IgS-D N-glycome profile to reflect CRC progression was assessed through Mann-Whitney U tests and multivariate analysis. A total of 43 distinct N-glycans were identified in IgS-D. Notably, a significant reduction in serum IgS-D mannosylated N-glycans was observed in CRC patients compared to healthy controls. Further analysis of individual N-glycans revealed significant differences and diagnostic potential in five specific N-glycans: H5N2 (AUC = 0.868), H6N2 (AUC = 0.73), H5N4S1 (AUC = 0.800), H5N5S1F1 (AUC = 0.713), and H5N4S2F1 (AUC = 0.689). A panel comprising these five N-glycans demonstrated high diagnostic accuracy for CRC (AUC = 0.924). The N-glycosylation profile of serum IgS-D is closely associated with CRC progression. Specific N-glycan signatures provide robust discrimination between CRC patients and healthy controls, warranting further investigation into the underlying molecular mechanisms.