RESUMEN
BACKGROUND: Lung adenocarcinoma is characterized by early asymptomatic progression and metastasis. Appearance of respiratory symptoms usually means the disease is aggravated. The aim of this study was to identify the protein profile in plasma of lung adenocarcinoma of stages I-IV, and look for novel diagnostic biomarkers. METHODS: Isobaric tags for relative and absolute quantification (iTRAQ) coupled with two dimensional liquid chromatography - tandem mass spectrometry technology (2D LC-MS/MS) was applied to separate and identify differential expression of proteins in plasma specimens from 10 healthy individuals, 10 patients with pneumonia, 7 patients with lung adenocarcinoma of stages I-II, respectively, and 10 patients with lung adenocarcinoma of stages III-IV, then analyze the functions of the differential expression of proteins by bioinformatics. RESULTS: ADAMTS-like protein 4, Fibrinogen-like protein 1 precursor, secretoglobin family 3A member 2 and haptoglobin were up-regulated in patients with lung adenocarcinoma by proteomics analysis, and the expression levels of SCGB3A2 and Hp by ELISA were consistent. Pathway analysis of identified differential expression of proteins showed they were mainly involved in chemokine/p53/TGF-beta signaling pathway. CONCLUSIONS: Plasma SCGB3A2 is a potential maker for diagnosis of primary pulmonary adenocarcinoma. Abnormal post-translational protein modification may be associated with the progression of lung cancer.