Circulating exosomes contain protein biomarkers of metastatic non-small-cell lung cancer

The present study aimed to investigate the overall changes in exosomal proteomes in metastatic and non-metastatic non-small-cell lung cancers (NSCLC) and healthy human serum samples, and evaluate the potential of serum exosomal biomarkers to predict NSCLC metastasis. Tandem mass tags combined with multidimensional liquid chromatography and mass spectrometry analysis were used for screening the proteomic profiles of serum samples. Quantitative proteome, significant pathway, and functional categories of patients with metastatic and non-metastatic NSCLC and healthy donors were investigated. In total, 552 proteins of the 628 protein groups identified were quantified. Bioinformatics analysis indicated that quantifiable proteins were mainly involved in multiple biological functions, metastasis-related pathways. Moreover, lipopolysaccharide-binding proteins (LBP) in the exosomes were found to be well distinguished between patients with metastatic and patients with non-metastatic NSCLC. Area under the curve (AUC) was 0.803 with a sensitivity of 83.1% and a specificity of 67% (P < .0001). Circulating LBP were also well distinguishable between metastatic and non-metastatic NSCLC, the AUC was 0.683 with a sensitivity of 79.5% and a specificity of 47.2% (P = .005). This novel study provided a reference proteome map for metastatic NSCLC. Patients with metastatic and non-metastatic NSCLC differed in exosome-related proteins in the serum. LBP might be promising and effective candidates of metastatic NSCLC.