Quantitative proteomic analysis for high-throughput screening of differential glycoproteins in hepatocellular carcinoma serum

Objective: Hepatocellular carcinoma(HCC) is a leading cause of cancer-related deaths. Novel serum biomarkers are required to increase the sensitivity and specificity of serum screening for early HCC diagnosis. This study employed a quantitative proteomic strategy to analyze the differential expression of serum glycoproteins between HCC and normal control serum samples.Methods: Lectin affinity chromatography(LAC) was used to enrich glycoproteins from the serum samples. Quantitative mass spectrometric analysis combined with stable isotope dimethyl labeling and 2D liquid chromatography(LC) separations were performed to examine the differential levels of the detected proteins between HCC and control serum samples. Western blot was used to analyze the differential expression levels of the three serum proteins.Results: A total of 2,280 protein groups were identified in the serum samples from HCC patients by using the 2D LC-MS/MS method. Up to 36 proteins were up-regulated in the HCC serum, whereas 19 proteins were down-regulated. Three differential glycoproteins, namely, fibrinogen gamma chain(FGG), FOS-like antigen 2(FOSL2), and α-1, 6-mannosylglycoprotein 6-β-N-acetylglucosaminyltransferase B(MGAT5B) were validated by Western blot. All these three proteins were up-regulated in the HCC serum samples.Conclusion: A quantitative glycoproteomic method was established and proven useful to determine potential novel biomarkers for HCC.