Site-specific N-glycan alterations on haptoglobin as potential biomarkers for distinguishing intrahepatic cholangiocarcinoma from hepatocellular carcinoma.

Intrahepatic cholangiocellular carcinoma (ICC) is a challenging malignancy marked by subtle early symptoms and a high mortality rate, making effective diagnostic markers crucial for early detection and improved patient outcomes. Currently, the conventional diagnosis of ICC is not easily distinguishable from Hepatocellular Carcinoma (HCC) and lacks highly specific and sensitive diagnostic markers. Protein glycosylation, pivotal in biological processes, shows promise for cancer biomarkers due to its association with disease progression. This study aims to develop a novel biomarker discovery framework for ICC utilizing site-specific quantitative N-glycoproteomics to overcome the limitations of existing diagnostic approaches. Employing a tandem mass tag (TMT)-based quantitative analysis, we profiled serum glycoproteins from ICC, HCC, and control cohorts at site-specific glycosylation level. The identified markers underwent further validation in an independent cohort using label-free quantitative methods. Ultimately, we identified five site-specific N-glycans on haptoglobin (HP) as potential biomarkers (AUC > 0.9) for distinguishing ICC from HCC. This finding represents a considerable advance over traditional biomarkers, highlighting the significance of protein glycosylation alterations in ICC pathogenesis. This research, therefore, sets a new precedent for biomarker discovery in ICC, with potential applications in other cancers characterized by glycosylation abnormalities.