Serum protein biomarkers screening in HCC patients with liver cirrhosis by ICAT-LC-MS/MS

The prognosis of HCC remains poor mainly because of the lack of diagnosis biomarkers especially in patients with cirrhosis background.

To identify serum biomarkers for HCC, we use cleavable stable isotope labeling (cICAT) combined with LC-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) to compare the serum proteome between liver cirrhosis and HCC patients. Sera from nine liver cirrhosis patients and nine HCC patients were selected for screening study. Then the alpha-1-acid glycoprotein (AGP) was chosen for validation by western blot. AGP was measured in the separate validation study including 52 HCC patients and 40 liver cirrhosis patients by rate nephelometry. Its value for HCC diagnosis from liver cirrhosis was also appreciated through receiver operating curve (ROC).

We quantified and identified 31 different proteins which include AGP, complement C4, haptoglobin, alpha-1-antitrypsin precursor, alpha-2-macroglobulin precursor, prothrombin precursor and ubiquitin carboxyl-terminal hydrolase 44 (USP44), etc. The serum concentration of AGP in HCC patients (n = 52) was significantly higher than in liver cirrhosis (n = 40) (P < 0.005) in validation study. AGP was useful for discrimination of the HCC cases from LC patients when the AFP levels were below 500 ng/ml. The area under curve (AUC) of the AGP and the combination of AGP and AFP were 0.834 (P < 0.0005, 95% CI: 0.734-0.934) and 0.880 (P < 0.0005, 95% CI, 0.789-0.970) separately, which are higher than AFP alone (0.538, P = 0.604, 95% CI: 0.386-0.689).

cICAT combined with LC-MS/MS-based serum proteome analysis can be useful in the screening of serum biomarkers for HCC. Alpha-1-acid glycoprotein combining AFP could aid the diagnosis of HCC.