o:36915 Circulating extracellular vesicles in liver and pancreatic cancer: an initial assessment of sialylation en Background: Extracellular vesicles (EVs) are cell-derived, membrane-surrounded vesicles that carry various bioactive molecules and deliver them to recipient cells. They are considered mini-maps of their cells of origin. Altered tissue/cell glycosylation is a hallmark of different cancers but little is known about how these changes affect circulating EVs. One of the most prevalent changes is sialylation, the addition of sialic acid (Sia) to galactose or N-acetylgalactosamine at the terminal position of glycan chains. Starting from data on the changes in sialylation of liver and pancreatic cancer tissues, this study aimed to assess whether these changes are mirrored in related circulating EVs, specifically within large EV populations, previously indicated to comprise cancer-derived vesicles. This is important issue regarding designation of introductory studies of the functional and biomarker potential of these EVs. Materials and Methods: Serum samples were collected from patients with hepatocellular carcinoma (HCC, n = 5), pancreatic cancer (PC, n = 10), and healthy donors (HD, n = 10). Circulating EVs were isolated by differential centrifugation and ultracentrifugation. Their size distribution was analyzed using nanoparticle tracking analysis (NTA). Surface sialylation was assessed by fluorescent NTA (f-NTA) using Sambucus nigra agglutinin (SNA) and wheat germ agglutinin (WGA), which have distinct requirements for binding Sia residues. Statistical analyses were performed through GraphPad Prism 8.0 applying the Kruskal-Wallis test. Results: Median (IQR) EV sizes from HCC (146 nm (144.5-150.8 nm)) and PC (155.5 nm (151.5-160.4 nm)) were significantly higher than those from HD (126.4 nm (123.3-128.9 nm)) (P < 0.001). Large EVs (>200 nm) were more abundant in cancers (~30%) compared to HD (~10%). There was no statistically significant difference (P > 0.05) in the sizes of SNA- and WGA-reactive EVs between cancers and HD. The proportion of SNA-reactive large EVs was similar between cancer patients and HD (~40%), whereas the proportion of WGA-reactive large EVs was similar between HCC and HD (~30%), but reduced in PC (~20%). Conclusions: The median EVs size and the ratio of large EVs were increased in both HCC and PC in comparison to HD. This increase is accompanied by the changes in surface sialylation seen as decrease in sialic acid-binding lectins reactivity, notably in PC. The changes in EVs sialylation were opposite to those detected in liver and pancreatic cancer tissue. Extracellular vesicles, hepatocellular carcinoma, nanoparticle tracking analysis, pancreatic cancer, sialic acid 1552101 3009-3848 2025-10-31T10:02:43.312Z 44 yes 46 Sanja Goč University of Belgrade, Institute for the Application of Nuclear Energy, Serbia dr bioloških nauka 0000-0002-6104-693X Filip Janjić University of Belgrade, Institute for the Application of Nuclear Energy INEP, Serbia dr medicinskih nauka – veterinarska medicina person 0000-0002-5121-1145 Ninoslav Mitić University of Belgrade, Institute for the Application of Nuclear Energy INEP, Serbia dr bioloških nauka person 0000-0003-2756-6517 Tamara Janković University of Belgrade, Institute for the Application of Nuclear Energy INEP, Serbia Magistar farmacije-medicinski biohemičar person 0000-0002-8188-0921 Milan Jovanović Department of Abdominal Surgery, Military Medical Academy, Belgrade, Serbia person Zoran Rujanovski Department of Abdominal Surgery, Military Medical Academy, Belgrade, Serbia person Miroslava Janković University of Belgrade, Institute for the Application of Nuclear Energy INEP, Serbia dr bioloških nauka person 0000-0002-7889-5110 application/pdf 1956707 https://phaidrabg.bg.ac.rs/o:36915 no yes 18 70 92000004 11A29 Circulating extracellular vesicles in liver and pancreatic cancer: an initial assessment of sialylation 121 Abstract Book – SDIR-7 Pasterova 14, 11000 Beograd Srpsko društvo istraživača raka 2025