Proteomic analysis of pleural effusion from lung adenocarcinoma patients by shotgun strategy

To construct a protein catalogue of malignant pleural effusion from lung adenocarcinoma patients and to screen the potential candidates of biomarkers for diagnostic value in human lung adenocarcinoma. Five malignant pleural effusion samples of lung adenocarcinoma patients were collected from January 2009 to September. A composite sample was analyzed using shotgun strategy. Pleural effusion samples were separated by means of SDS-PAGE. Proteomic analysis was performed by 1D-LC-MS/MS, and then the proteins were identified using SEQUEST software and protein database search. Among 230 unique proteins, 123 proteins were identified with higher confidence levels (at least two unique peptide sequences matched). Most of these proteins have been reported in plasma. However, there are 7 proteins, including JUP protein, suprabasin, annexin A2, transforming growth factor-beta-induced protein ig-h3 (beta ig-h3), V-set and immunoglobulin domain-containing protein 4 precursor, ifapsoriasin 2 and actin, cytoplasmic 1 have not been reported in serum. Seven proteins may represent potential candidates of biomarkers. Annexin A2 is of special interest since it may play a role in the regulation of intercellular adhesion and cell proliferation.