Proteomic profiling of extracellular vesicles in patients with biliary tract cancers

Abstract Background and Aim: Biliary tract cancers (BTCs) have a poor prognosis. One of the reasons for the prognosis is the difficulty of early diagnosis. The absence of a sufficient biomarker to screen for BTCs in high-risk populations makes the patient to be recognized in advanced status. Therefore, it is urgent to discover a biomarker for early detection of BTCs. This study analyzed extracellular vesicle (EV) peptides to find a new serum biomarker of BTCs. Methods: Plasma samples were obtained from 5 healthy people as control, 10 from patients with benign biliary diseases such as choledocholithiasis, sclerosing cholangitis, and gallbladder polyp, and 29 from BTCS patients. The EV peptides have been obtained from 2.5ml of patient plasma. The EV peptide samples were analyzed by liquid chromatography-data-dependent acquisition-tandem mass spectrometry (LC-DDA-MS/MS). The acquired peptides and proteins were investigated by searching in Fragpipe-MSFragger. Characterization was performed using the EVs database of previous studies. After that, Differential Expression Protein (DEP) analysis and Pathway/GO analysis are performed to know the biological process. Results: Total 25,382 peptides and 3,313 proteins were defined (PSM, peptide-level FDR 1%). Most of the gene ontology biological processes were related to vesicle-mediated transport. On DEP analysis, total 72 proteins were up-regulated, and 29 proteins were down-regulated. Compared to cancer samples, 9 proteins were up-regulated to both healthy and benign samples and 2 were down-regulated. According to biological process/pathway analysis, up-regulated 9 proteins were mostly related to cytoskeleton/ECM and Hemostasis. Down-regulated 2 proteins were related to endocytosis and immunity. Conclusions: By analyzing EV peptides, a total of 11 proteins have been identified. With validation experiments, we expect to finalize biomarker candidates. Citation Format: Dong Uk Kim, Sunghee Park, Sung Yong Han, Daye Jeon, Hyeji Lee, Jonghyun Lee, Hyeong Seok Nam, Dong Wook Lee, Chang-Min Cho, Min Kyu Jung, Jun Heo, Un-Beom Kang, Seong-Jun Park, Sunghyun Huh, Yourae Shin. Proteomic profiling of extracellular vesicles in patients with biliary tract cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3327.