OBJECTIVEThis study was designed to establish the two-dimensional electrophoresis profiles with high resolution and reproducibility from human lung squamous cell carcinoma tissue and paired tumor-adjacent normal bronchial epithelial tissue, and to identify differential expression of tumor-associated proteins by using proteome analysis.

METHODSComparative proteome analysis of human lung squamous carcinoma and paired normal bronchial mucosa adjacent to tumors from 20 cases were carried out. Total proteins of the carcinoma tissue and normal bronchial mucosa were separated by means of immobilized pH gradient-based two-dimensional gel electrophoresis (2-DE). The differentially expressed proteins were analyzed and identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS).

RESULTS(1) Seventy-six differentially expressed proteins were screened by analyzing the electrophoretic maps of the 20 carcinoma and control mucosa tissues. (2) Sixty-eight differential proteins were identified by peptide mass fingerprinting (PMF). Some proteins were products of oncogenes and others were involved in the regulation of cell cycle and signal transduction. (3) The expression of three proteins mdm2, c-Jun and EGFR, correlated with lung squamous carcinoma, were detected by immunohistochemical staining and Western blot analysis. The results showed that the expression of mdm2, c-Jun and EGFR were up-regulated in lung squamous carcinomas, whereas down-regulated in control normal mucosa. It was consistent with our proteome analysis results. Those results suggested that those proteins may play roles in the carcinogenesis of lung squamous carcinoma.

CONCLUSIONsixty-eight differentially expressed proteins were successfully characterized by comparative proteome analysis. Those results may provide scientific foundation for screening the molecular biomarkers which can be used in diagnosis and treatment of lung squamous carcinoma, as well as to improve patients' prognosis and provide a new clue for carcinogenesis research of lung squamous cell carcinoma.