S1890 Characterisation of Serum Proteins in Biliary Tract Cancer, PSC and Iac Using 2-Dimensional Difference Gel Electrophoresis and Tandem Mass Spectrometry

Abstract

Distinguishing biliary tract cancer (BTC: cholangiocarcinoma and gallbladder carcinoma) from benign biliary disease such as pre-malignant primary sclerosing cholangitis (PSC) or immunoglobulin G4-associated cholangitis (IAC) can be difficult. Serum markers such as CA19.9 and immunoglobulin G4 lack sensitivity and specificity. There is a need for better biomarkers to differentiate these clinically similar diseases. We aimed to perform serum immunoaffinity depletion, 2-dimensional difference gel electrophoresis and liquid chromatography tandemmass spectrometry to identify differential biomarkers in benign and malignant biliary disease and healthy volunteers. Blood was prospectively collected from 37 patients with BTC, 11 with PSC, 7 with IAC and 30 healthy volunteers. Serum was pooled into the four clinical groups and immunoaffinity depleted via fast protein liquid chromatography to remove highly abundant proteins. Following 2-dimensional difference gel electrophoresis using minimal labelling Cy-dyes, gels were scanned then analysed with DeCyderTM software. Protein spots with a >2-fold differential expression (p 37 IU/mL) CA 19.9 levels. 61 protein spots were picked, of which 34 were upand 13 downregulated in BTC vs healthy, 32 upand 9 down-regulated in BTC vs PSC, and 7 upand 12 down-regulated in PSC vs IAC. Leucine-rich glycoprotein, apolipoprotein A-IV and E, MASP2, CLEC3B, RAD1 and vimentin were up-regulated and Hsp90, C4BPA and SERPIND1 down-regulated in BTC vs PSC. Carbonic anhydrase 1, lumican and twinfilin-2 were upregulated and IgG4 chain C region and MASP2 were down-regulated in PSC vs IAC, respectively. Serum validation of putative markers is underway. Differentially expressed serum proteins in benign and malignant biliary disease were identified using this proteomic approach. These putative markers may be useful in monitoring patients with PSC who are at increased risk of BTC.