Integrative Quantitative Analysis of Platelet Proteome and Site-Specific Glycoproteome Reveals Diagnostic Potential of Platelet Glycoproteins for Liver Cancer

The role of peripheral blood platelets as indicators
of cancer
progression is increasingly recognized, and the significance of abnormal
glycosylation in platelet function and related disorders is gaining
attention. However, the potential of platelets as a source of protein
site-specific glycosylation for cancer diagnosis remains underexplored.
In this study, we proposed a general pipeline that integrates quantitative
proteomics with site-specific glycoproteomics, allowing for an in-depth
investigation of the platelet glycoproteome. With this pipeline, we
generated a data set comprising 3,466 proteins with qualitative information,
3,199 proteins with quantitative information, 3,419 site-specific
glycans with qualitative information and 3,377 site-specific glycans
with quantitative information from peripheral blood platelets of hepatocellular
carcinoma (HCC) patients, metastatic liver cancer (mLC) patients,
and healthy controls. The integrated analysis revealed significant
changes in platelet protein N-glycosylation in liver cancer patients.
Further systems biology analysis and lectin pull-down-coupled ELISA
assays in independent clinical samples confirmed two N-glycoproteins
with specific glycan types, complement C3 (C3) with oligomannose modification
and integrin β-3 (ITGB3) with sialylation, as potential biomarkers
distinguishing liver cancer patients from healthy individuals, without
differentiating between HCC and mLC patient group. These findings
highlight the potential of platelet protein glycosylation as biomarkers.