RNA profiles in serum and urine extracellular vesicles of patients with cholangiocarcinoma mimicking tumor expression: novel liquid biopsy approach

Cholangiocarcinoma (CCA) represents a heterogeneous group of biliary cancers with poor prognosis. Although the aetiology is generally unknown, factors like Primary Sclerosing Cholangitis (PSC) predispose to its development. Simultaneously, around 80% of patients with PSC have concomitant Ulcerative Colitis (UC). As there are no specific and sensitive biomarkers for the non-invasive diagnosis of CCA, we aimed to analyse the RNA content of serum and urine extracellular vesicles (EVs) to find accurate biomarkers of CCA that could be reflecting tumor behaviour. The transcriptomic analysis of these EVs showed a differential profile of RNAs in patients with CCA compared to healthy individuals or patients with other diseases (PSC and UC), presenting some RNAs high diagnostic values to distinguish patients with CCA. Moreover, the differential abundance of several RNAs in serum and/or urine EVs correlated with the deregulated expression of those transcripts in CCA tissue compared to surrounding liver (TCGA and Copenhagen cohorts), in tumor (EGI1, TFK1) and normal cholangiocyte (NHC) cell lines as well as in EVs secreted by those cell lines; pinpointing the potential involvement of those RNAs not only as liquid biopsy biomarkers but also as potential mediators of CCA pathogenesis. Total RNA obtained from normal (NHC) and tumoral (EGI1 and TFK1) cholangiocyte cell lines and from extracellular vesicles (EVs) isolated from serum, urine and cholangiocyte cell line supernatant