Comparative evaluation of methods for isolating extracellular vesicles from ICC cell culture supernatants: Insights...

Extracellular vesicles (EVs) are nanoscale structures involved in intercellular communication and play a key role in cancer pathology. Intrahepatic cholangiocarcinoma (ICC) is a highly invasive malignancy marked by abnormal sialylated glycosylation. Analyzing proteins and glycans in EVs provides insights into ICC molecular subtyping and mechanisms. Optimizing EV isolation methods for ICC-derived EVs enables comprehensive proteomic and glycomic analysis.

We systematically evaluated five EV isolation methods-Ultracentrifugation (UC), exoEasy, Total Exosome Isolation (TEI), EVtrap, and ÄKTA-by analyzing the biophysical properties, proteomic profiles, and glycomic structures of EVs. Subsequently, we applied TMT-based quantitative proteome and light/heavy methylamine labeling for the quantification of sialylated N-glycan linkage isomers to investigate alterations in proteins and N-glycans within EVs secreted by HuCCT1 and HCCC-9810 cells with overexpressing ST6 β‑galactoside α2,6‑sialyltransferase 1 (ST6GAL1).

By evaluating the biophysical properties, proteome, and N-glycome of EVs extracted using five different methods, UC was identified as the optimal approach for this study, as it offered a balance between operational complexity, cost-effectiveness, and the preservation of EVs activity. In this study, a total of 1,928 high-confidence proteins and over 84 high-confidence glycans were quantified. EVs secreted by HuCCT1 and HCCC-9810 cells overexpressing ST6GAL1 exhibited consistent upregulation of 16 proteins, consistent downregulation of 10 proteins, as well as consistent upregulation of 3 glycans and consistent downregulation of 3 glycans.

Quantitative proteomic and glycomic analysis of ICC-derived EVs revealed that ST6GAL1 overexpression led to significant alterations in proteins involved in cancer cell adhesion and glycosylation pathways, along with specific changes in N-glycan structures. Notably, these modifications extended beyond α2,6-sialylation, suggesting that interactions between glycosyltransferases and glycans may drive these alterations.