Bile Proteomic Profiles Differentiate Cholangiocarcinoma From Primary Sclerosing Cholangitis and Choledocholithiasis §Δ

Abstract

Early detection of malignant biliary tract diseases, especially cholangiocarcinoma (CC) in patients with primary sclerosing cholangitis (PSC), is very difficult and often comes too late to give the patient a therapeutic benefit. We hypothesize that bile proteomic analysis distinguishes CC from nonmalignant lesions. We used capillary electrophoresis mass spectrometry (CE-MS) to identify disease-specific peptide patterns in patients with choledocholithiasis (n 5 16), PSC (n 5 18), and CC (n 5 16) in a training set. A model for differentiation of choledocholithiasis from PSC and CC (PSC/CC model) and another model distinguishing CC from PSC (CC model) were subsequently validated in independent cohorts (choledocholithiasis [n 5 14], PSC [n 5 18] and CC [n 5 25]). Peptides were characterized by sequencing. Application of the PSC/CC model in the independent test cohort resulted in correct exclusion of 12/14 bile samples from patients with choledocholithiasis and identification of 40/43 patients with PSC or CC (86% specificity, 93% sensitivity). The corresponding receiver operating characteristic (ROC) analysis revealed an area under the curve (AUC) of 0.93 (95% confidence interval [CI]: 0.82-0.98, P 5 0.0001). The CC model succeeded in an accurate detection of 14/18 bile samples from patients with PSC and 21/25 samples with CC (78% specificity, 84% sensitivity) in the independent cohort, resulting in an AUC value of 0.87 (95% CI: 0.73-0.95, P 5 0.0001) in ROC analysis. Eight out of 10 samples of patients with CC complicating PSC were identified. Conclusion: Bile proteomic analysis discriminates benign conditions from CC accurately. This method may become a diagnostic tool in future as it offers a new possibility to diagnose malignant bile duct disease and thus enables efficient therapy particularly in patients with PSC. (HEPATOLOGY 2011;53:875-884)

A comparative proteomic analysis of bile for biomarkers of cholangiocarcinoma

“…Several groups have employed different proteomic approaches to identify tumor-specific makers for CCA, and in these studies, protein candidates were verified in bile and blood by immunoblot and/or ELISA. [6][7][8][9][10] In this study, we employed a quantitative proteomic approach to investigate the differential protein expression in bile samples from different gross types of CCA and non-CCA patients. A protein candidate was then verified in CCA tissues, the upstream protein sources of the tumor protein in bile.…”

“…[8][9][10] Both single-protein biomarker and peptide panels have been validated for diagnostic potential for CCA diagnosis. [6][7][8][9][10] In this study, using iTRAQ labeling, peptide fractionation by OFFGEL electrophoresis and LC-MS/MS identified 1243 unique proteins. In all, 63 proteins were overexpressed in CCA bile samples compared to non-CCA bile.…”

Biliary Proliferative Lesions in the Sprague-Dawley Rat

“…Elevated serum activities of other enzymes, such as ALP and 5 0 nucleotidase, have been associated with biliary diseases; however, they are also increased with hepatocellular injury and with a variety of non-hepatic disorders. Because biliary epithelium comprises less than 5% of the liver parenchyma, the challenges of accurately identifying aberrations in this small cell population via a peripheral blood sample have led an increasing number of investigators to explore bile constituents as alternatives (Lankisch et al 2011). …”

Update on primary sclerosing cholangitis

“…In serum, a proteomic study report the potential diagnostic improvement achieved by including serum leucinerich a-2-glycoprotein (LRG1) and IL6 in prediction models for cholangiocarcinoma [141]. In bile, a panel of 22 peptides detected in a screening panel was shown to discriminate between cholangiocarcinoma and PSC with an area under the receiver operating characteristics curve of 87% [142], correctly detecting 8 out of 10 cases of cholangiocarcinoma complicating PSC. In urine, a similar approach led to comparable results [143], with correct classification of 10 out of 10 cases of cholangiocarcinoma arising in the context of PSC.…”