Identification of two portal vein tumor thrombosis associated proteins in hepatocellular carcinoma: protein disulfide-isomerase A6 and apolipoprotein A-I.

BACKGROUND AND AIM: Portal vein tumor thrombus (PVTT) is one of the factors that can affect prognosis and survival of hepatocellular carcinoma (HCC). In the present study, we aimed to find out some biomarkers associated with vascular invasion features of HCC with the method of comparative proteomic analysis.
METHODS: The proteins were extracted from a pair of HCC tissues with PVTT and without PVTT, and then separated by two-dimensional polyacrylamide gel electrophoresis. Differentially expressed protein spots were identified by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Further analysis of two proteins were completed using real-time fluorescence quantitative polymerase chain reaction and western-blot in 40 HCC tissues with PVTT (n = 20) and without PVTT (n = 20).
RESULTS: Among 465 protein spots displayed on the gels, 33 unique proteins (> twofold change, P < 0.01) were identified, including 24 upregulated in HCC tissue without PVTT and nine upregulated in HCC tissue with PVTT. The real-time fluorescence quantitative PCR showed no statistically significant difference between HCC tissues with PVTT and without PVTT for mRNA expressions of protein disulfide-isomerase, A6 (PDI A6) (P = 0.137) and apolipoprotein A-I (Apo A-I) (P = 0.718). However, compared with HCC tissues without PVTT, protein expression of PDI A6 was higher in HCC tissues with PVTT (P < 0.001), while protein expression of Apo A-I was lower in HCC tissues with PVTT (P = 0.012).
CONCLUSIONS: PDI A6 and Apo A-I are closely related to vascular invasion feature of HCC.