RESUMO
<p><b>OBJECTIVE</b>To identify protein markers for the early diagnosis of pancreatic cancer by a comparative proteomic method.</p><p><b>METHODS</b>Comparative analysis on the pancreatic peripheral blood protein profiling from 20 pancreatic cancer patients, 10 chronic pancreatitis patients and 20 cancer-free controls from May 2007 to September 2008 was carried out by two-dimensional fluorescence electrophoresis (2D-DIGE). Differentially expressed proteins were identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). The significance difference proteins were confirmed by Western-blot.</p><p><b>RESULTS</b>A differentially expressed proteins: complement 3 (C3) was identified. The gray level of C3 in pancreatic cancer tissue, chronic pancreatitis, and normal control group were 1.63 ± 0.28, 0.65 ± 0.13 (t = 11.81, P = 0.00) and 0.88 ± 0.19 (t = 9.93, P = 0.00), respectively. C3 was high expression in pancreatic cancer group compared with normal control group. The expression of C3 was higher in pancreatic cancer group than in chronic pancreatitis group. The high expression of C3 in pancreatic carcinoma was confirmed by Western blot.</p><p><b>CONCLUSIONS</b>2D-DIGE and MALDI-TOF-MS technology is a quick, easy and practical method to screen for specific biomarkers in serum of patients with pancreatic carcinoma. The identified protein C3 in this study may be as specific serum biomarkers of pancreatic carcinoma.</p>