Cell surface glycoprotein profiling of cancer cells based on bioorthogonal chemistry

Bioorthogonal chemistry refers to chemical reactions that can occur within a living system without altering native biochemical processes. Applications of this concept extend to studies on a group of biomolecules that includes glycans, proteins, and lipids. In this study, a strategy for isolating cell surface glycoproteins and based on bioorthogonal chemistry was employed to identify new cancer-related glycoproteins. A novel alkyne reagent containing one disulfide bond was synthesized for the enrichment of glycoproteins metabolized with peracetylated N-azidoacetylmannosamine, which was applied on three different cancer cell lines, and all isolated proteins were analyzed by high-performance liquid chromatography-tandem mass spectrometry. The strategy of purifying cell surface glycoproteins introduced in this article was shown to be reliable, and a total of 56 cell surface glycoproteins were identified. Neuronal cell adhesion molecule was found uniquely expressed in A549 lung adenocarcinoma, and its expression in non-small-cell lung carcinomas was detected by immunohistochemistry. Furthermore, a significant increase of neuronal cell adhesion molecule expression was identified in non-small-cell lung adenocarcinoma compared with adjacent noncancerous tissues, and could be a novel potential target and marker in cancer treatment and detection.