Integrated N -glycoproteomics Analysis of Human Saliva for Lung Cancer.

Aberrant protein N -glycosylation is a cancer hallmark, which has great potential for cancer detection. However, large-scale and in-depth analysis of N -glycosylation remains challenging because of its high heterogeneity, complexity, and low abundance. Human saliva is an attractive diagnostic body fluid, while few efforts explored its N -glycoproteome for lung cancer. Here, we utilized a zwitterionic-hydrophilic interaction chromatography-based strategy to specifically enrich salivary glycopeptides. Through quantitative proteomics analysis, 1492 and 1234 intact N -glycopeptides were confidently identified from pooled saliva samples of 10 subjects in the nonsmall-cell lung cancer group and 10 subjects in the normal control group. Accordingly, 575 and 404 N -glycosites were revealed for the lung cancer group and normal control group. In particular, 154 N -glycosites and 259 site-specific glycoforms were significantly dysregulated in the lung cancer group. Several N -glycosites located at the same glycoprotein and glycans attached to the same N -glycosites were observed with differential expressions, including haptoglobin, Mucin-5B, lactotransferrin, and α-1-acid glycoprotein 1. These N -glycoproteins were mainly related to inflammatory responses, infectious diseases, and cancers. Our study achieved comprehensive characterization of salivary N -glycoproteome, and dysregulated site-specific glycoforms hold promise for noninvasive detection of lung cancer.