Shotgun proteomics of human bile in hilar cholangiocarcinoma.

The need to find biomarkers for hepatobiliary diseases including cholangiocarcinoma (CCA) has led to an interest in using bile as a proximal fluid in biomarker discovery experiments, although there are inherent challenges both in its acquisition and analysis. The study described here greatly extends previous studies that have started to characterise the bile proteome. Bile from four patients with hilar CCA was depleted of albumin and immunoglobulin G and analysed by GeLC-MS/MS. The number of proteins identified per bile sample was between 378 and 741. Overall, the products of 813 unique genes were identified, considerably extending current knowledge of the malignant bile proteome. Of these, 268 were present in at least 3 out of 4 patients. This data set represents the largest catalogue of bile proteins to date and together with other studies in the literature constitutes an important prelude to the potential promise of expression proteomics and subsequent validation studies in CCA biomarker discovery.