OBJECTIVETo screen low molecular weight protein biomarkers relevant to portal vein tumor thrombi (PVTT) in serum of hepatocellular carcinoma (HCC) patients.

METHODSSerum samples were obtained from 12 healthy volunteers, 12 HCC patients without PVTT and 12 HCC patients with PVTT. Using two-dimensional gel electrophoresis (2-DE) in which the second dimension was 16% SDS-PAGE, serum protein images of the 3 groups were analyzed by ImageMaster software. The differential protein spots were further identified by MALDI-TOF MS/MS.

RESULTSComparing the results using 12.5% SDS-PAGE gel, there were more protein bands (between 3 x 10(3) and 20 x 10(3)) and low molecular weight (MW) protein spots (less than 20 x 10(3)) were clearly shown in the 16% SDS-PAGE gel. Fifteen differential protein spots representing 5 proteins were found in the 3 groups by inter-class comparison and they were then identified. Compared with those in the healthy group, apolipoprotein A-I, lipoprotein CIII, transthyretin and DNA topoisomerase II were all down regulated in HCC groups and haptoglobin-2 was over expressed. All 5 proteins decreased more in the PVTT group than in the non-PVTT group.

CONCLUSIONThe expression of low MW serum protein obviously changes in the beginning and in the progressive stage of HCC, and differentially expressed low MW proteins might be potential biomarkers in an early prognostic prediction and surveillance in the treatment for HCC and PVTT.