Increased expression of the high-mannose M6N2 and NeuAc3H3N3M3N2F tri-antennary N-glycans in cholangiocarcinoma

Changes in protein glycosylation have been reported in various types of cancer, including cholangiocarcinoma (CCA). Nanospray ionization-linear ion trap mass spectrometry (NSI-MS(n)) was used in the present study to determine the comparative structural glycomics of the N-linked glycans in the serum of patients with CCA compared with healthy controls. A total of 5 high-mannose and 4 complex N-linked glycans were detected. Mannose(7)-N-acetyl-glucosamine(2) was the most abundant structure among the high-mannose types (control 12.12±2.54 vs. CCA 9.27±2.66%), whereas NeuAc2H2N2M3N2 predominated the complex types (control 61.17±2.55 vs. CCA 64.68±4.23%). The expression of 3 different N-glycans differed significantly between the CCA cases and controls. These included mannose(6)-N-acetyl-glucosamine(2) (P=0.044), mannose(9)-N-acetyl-glucosamine(2) (Ρ=0.030) and NeuAc3H3N3M3N2F (Ρ=0.002). These three glycan structures may therefore be associated with tumor progression in CCA and may be useful for its diagnosis.