Proteomic Profiling of Human Hepatocellular Carcinoma Tissues by Two-Dimensional Electrophoresis and Mass Spectrometry

Hepatocellular carcinoma (HCC) is the most common tumor in the adult liver, with high relapse and mortality rates despite diverse treatment modalities. To identify novel HCC markers, we analyzed HCC and paired nontumor tissues from five early HCC patients (Edmondson grade I and 11) by two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). To obtain a detailed proteome map, narrow pH-range strips were utilized in the isoelectric focusing (IEF) step. A total of 44 2-D gels were obtained and more than 1,000 protein spots were detected. We successfully identified 85 differentially expressed protein spots, including 49 up-regulated and 36 down-regulated spots in HCC tissues, corresponding to 74 different proteins (44 up-regulated and 30 down-regulated). These differentially expressed proteins included well-known deregulated proteins in HCC such as heat shock protein (HSP) family and proliferating cell nuclear antigen (PCNA), consistent with previous studies. All 74 proteins were classified according to their functional categories described by Gene Ontology, shedding light on processes deregulated in hepatocarcinogenesis. Thirty-three proteins have not been reported in other HCC proteomic profiling analysis and, in particular, overexpression of transketolase (TKT) and second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pi (Smac/DIABLO) could be novel candidate markers for HCC. In summary, we profiled proteome alterations in HCC tissues, and these results may provide useful diagnostic and prognostic markers of HCC.