Proteomic profiles screening identified novel exosomal protein biomarkers for diagnosis of lung cancer.

BACKGROUND: Exosomes play important role in biological functions, including both normal and disease process. Multiple cell types can secret exosomes, which act as message carriers. Increased evidences reveal that exosomes are promising diagnosis biomarkers in malignant tumors. METHODS: In this study, we enrolled 78 participants, including 20 lung adenocarcinoma (LUAD), 18 lung squamous carcinoma (LUSC), 20 lung benign diseases (LUBN) and 20 healthy controls (NL) and we performed parallel reaction-monitoring (PRM)-mass spectrometry to screening the proteomic variation by label free analysis in exosomes from all groups, which has been widely used to quantify and detect target proteins. RESULTS: Total 14 protein were identified as candidate biomarkers, complement components C9, apolipoprotein B (APOB), filamin A (FLNA), guanine nucleotide binding protein G subunit 2 (GNB2), fermitin family homolog 3 (FERMT3) showed significantly differentiation in total lung cancer (LUAD and LUSC together), we then obtained combination analysis of 5 proteins and the area under the curve (AUC), sensitivity (SN) and specificity (SP) were 63.0%, 65.0%, and 75.0%, respectively, in comparison to NL group. And the LUAD combination panel, peroxiredoxin 6 (PRDX6), integrin alpha-IIb (ITGA2B) and hemoglobin subunit delta (HBD) revealed AUC was 95.0%, SN was 90.0% and SP was 95.0% in comparison to NL controls. In LUSC analysis, combination analysis of fibronectin 1 (FN1), pregnancy zone protein (PZP) and complement C1q tumor necrosis factor related protein 3 (C1QTNF3) showed that AUC was 88.1%, SN was 75.0%, SP was 100% in paralleled with NL group. Finally C9, FLNA, PZP were overexpressed in lung cancer H1299 and A549 cell lines and the results indicated that C9 acted as oncogenic role by increasing proliferation, migration and invasion of lung cancer cells, while FLNA and PZP played tumor-suppression by inhibition biological functions of lung cancer cells. CONCLUSION: Taken together, our study revealed multiple exosomal proteins which could be applied as candidate biomarkers in diagnosis of lung cancer.