Identification of proteasome subunit alpha type-1 as a novel biomarker in HBV-associated hepatocellular carcinoma tissue interstitial fluid by proteomic analysis.

Differentially expressed proteins between HCC TIF and normal interstitial fluid of adjacent nontumor tissues were identified through comparative proteomics approach. Then, two-dimensional gel electrophoresis (2-DE), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), In-Cell Western technique, and reverse transcription-polymerase chain reaction (RT-PCR) were used to verify differentially expressed proteins. As a result, through 2-DE, 69 spots were roughly recognized as differentially expressed protein spots, while 44 proteins were identified as differentially expressed spots through MALDI-TOF-MS. Of the identified differential protein spots, 31 were significant according to the bioinformatics analysis results. Proteasome subunit alpha type-1 (PSMA1) expression was down-regulated in HCC TIF. Thus, PSMA1 is considered as a potential biomarker for HBV-associated hepatocellular carcinoma.