Characterization of apolipoprotein A-I as a potential biomarker for cholangiocarcinoma.

Serum samples from 60 cholangiocarcinoma (CC), 60 benign diseases of hepatobiliary and 53 normal individuals were analysed by SELDI-TOF-MS (Surface Enhanced Laser Desorption/Ionization Time of Flight Mass Spectrometry). It was found that a 28 k m/z peak was significantly decreased in CC and retained discriminatory value between CC and normal group, also between CC and benign groups. Then 1-D, 2-D gel electrophoresis and tandem mass spectroscopy were employed to isolate and identify the protein that correlates with observed SELDI-TOF-MS (m/z) value. The results demonstrated that 28 k m/z peak was apolipoprotein A-I (ApoA-I) and its identity was further validated by immunodepletion and Western blotting analysis. Subsequently, it was inspiring found that the decreased level of ApoA-I analysed by enzyme linked immunosorbent assay was consistent with SELDI-TOF-MS analysis. Therefore, it suggested that ApoA-I could be a potential useful biomarker for CC.