Liquid Biopsy for Pancreatic Cancer by Serum Extracellular Vesicle-Encapsulated Long Noncoding RNA HEVEPA

Objectives: The role of long noncoding RNAs (lncRNAs) in pancreatic ductal adenocarcinoma (PDAC) remain unclear. Extracellular vesicle (EV)-encapsulated RNAs could be effective targets for liquid biopsy. We aimed to identify previously unknown EV-encapsulated lncRNAs in PDAC and establish highly accurate methods for isolating EVs. Materials and Methods: Extracellular vesicles were isolated using existing and newly developed methods, namely, PEViA-UC and PEViA-IP, from serum samples of 20 patients with PDAC, 22 patients with intraductal papillary mucinous neoplasms, and 21 healthy individuals. Extracellular vesicle lncRNA expression was analyzed using digital PCR. Results: Gene expression analysis using cDNA microarray revealed a highly expressed lncRNA, HEVEPA, in serum EVs from patients with PDAC. We established PEViA-UC and PEViA-IP using PEViA reagent, ultracentrifugation, and immunoprecipitation. Although detection of EV-encapsulated HEVEPA using existing methods is challenging, PEViA-UC and PEViA-IP detected EV HEVEPA, which was highly expressed in patients with PDAC compared with non-PDAC patients. The detection sensitivity for discriminating PDAC from non-PDAC using the combination of HEVEPA and HULC, which are highly expressed lncRNAs in PDAC, and carbohydrate antigen 19-9 (CA19-9), was higher than that of HEVEPA, HULC, or CA19-9 alone. Conclusions: Extracellular vesicle lncRNAs isolated using PEViA-IP and CA19-9 together could be effective targets in liquid biopsy for PDAC diagnosis.