Although blood from first sight appears to be the most appropriate material, its use is associated with several difficulties. The 10 most abundant proteins in blood account for >90% of the total protein content.33 These most abundant proteins contain little information regarding the status of an organ33 and greatly inhibit the accurate detection of less abundant proteins that potentially contain more information.33 A few preliminary proteomic bile analyses in single NVP-AUY922 supplier patients suggested that this method could be feasible.13, 14, 16-18, 30, 34 Most of the studies applied sodium dodecylsulfate polyacrylamide gel

electrophoresis (SDS-PAGE) and liquid chromatography-mass spectrometry (LC-MS). In our study, capillary electrophoresis (CE) coupled to mass spectrometry (MS, CE-MS) was used for the first time to study proteomic profiles in bile. Although CE and LC possess similar resolution characteristics, the absence of a sieving matrix in CE provides several advantages over LC. No buffer gradients that require ramping of ionization parameters are needed to ensure stable flow; sample migration can be controlled by varying the electric field strength.35 The differentiation from PSC and CC was based on a peptide model of 22 peptides. Twelve

of those were identified by sequencing and are fragments of hemoglobin subunits, serum albumin, cytoplasmic actin, keratins, inter-alpha-trypsin inhibitor heavy chains, Ulixertinib chemical structure and the 14-3-3 zeta/delta protein (for details, see Table 3). Expression profiles of these peptide markers in PSC and CC patients may reflect changes in molecular pathways involved in proteolysis/protein catabolism, inflammation, apoptosis, and Thymidine kinase epithelial cell transformation.36-38 The increased abundance of a 14-3-3 zeta/delta protein derived peptide fragment (of

which the annotated mass spectrum is presented in Supporting Information Fig. 1) in patients with CC is of special interest, because 14-3-3 proteins are involved in many cellular processes, i.e., actin cytoskeletal organization, mitogenesis, cell adhesion, and apoptosis prevention. Hermeking39 described that cancer-associated down-regulation or loss of 14-3-3 proteins leads to an increased or unscheduled cell-cycle progression. In connection with decreased levels of peptides from cytokeratins and increased levels of actin, 14-3-3 may also be implicated in epithelial-mesenchymal transition,40, 41 with the latter recently associated with CC and invasive CC tumor growth.42, 43 However, further analyses have to be performed to investigate the role of 14-3-3 proteins in the pathogenesis of CC. A disease-specific biomarker panel to identify different bile-related diseases has never been evaluated so far. Our study focused on clinically diagnostic challenges such as the detection of malignant (CC) and premalignant (PSC) biliary lesions.