OBJECTIVETo screen serum biomarker candidates in prostate cancer with bone metastasis by two-dimensional gel electrophoresis (2-DGE) and mass spectrometry.

METHODSSerum samples were obtained from 5 prostate cancer patients with bone metastasis, and another 5 without it. After depletion of the most abundant protein albumin from the serum, the samples were separated by 2-DGE and analyzed with the ImageMaster 2D Platinum software. The differentially expressed protein spots in the serum of those with bone metastases were identified by peptide-fingerprinting with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS).

RESULTSCompared with the serum samples from those without bone metastasis, 10 protein spot-features were found to be significantly increased and 5 significantly decreased, and the 3 identified proteins, Zn-alpha2-glycoprotein (ZAG), haptoglobin and apolipoprotein C-III, were all increased in the bone-metastasis group.

CONCLUSIONThe combination of 2-DGE and mass spectrometry is an ideal platform and an effective means for the differential proteomic analysis of human sera. The identified proteins involved in the formation and progression of prostate cancer bone metastasis might be applied as biomarkers for bone metastasis from prostate cancer.