Lung cancer exosome specific protein 1(LESP-1) as a potential factor for diagnosis and treatment of non-small cell lung cancer.

e15550 Background: Exosomes are endosome-derived nano size (30-150 nm) extracellular microvesicles released from many cell types including cancer cells and encapsulated by cell membrane play a key role for cell to cell communication. Use of exosomes as a biomarkers in lung cancer is a rising nanotechnology in a liquid biopsy. We explored a role of an exosome specific marker and the relationship between pathological stage of lung cancer patients who underwent surgery and lung cancer specific exosome markers. Methods: Conditioned medium from non-small cell lung cancer (NSCLC) cells and human pulmonary alveolar endothelial cell (HPAEpiC) was collected and exosomes were isolated by size exclusion chromatography. Proteomics analysis was performed to investigate lung cancer specific proteins. Written informed consent was obtained from all human subjects (17 controls and 54 patients), approved by the Korea University Guro Hospital Institutional Review Bored. Plasma exosomes were isolated using dual size exclusion chromatography. We validated proteomics results with lung cancer exosome-specific protein 1 (LESP-1) ELISA assay and western blot assay in lung cancer patients with healthy control. Cancer cell lines with pCMV-CD63-GFP were transduced by lentiviral vectors containing LESP-1 shRNA. The distribution of GFP+ exosomes and cell migration were examined by immunocytochemistry (ICC) and cell migration assay. Results: We identified LESP1 by the proteomics analysis of exosomes from NSCLC cell lines, but not in HPAEpiC cell. Level of LESP1 was dramatically increased in exosomes from NSCLC cell lines and from NSCLC patients. LESP-1 concentration increased in lung cancer patients than healthy controls ( p < 0.0001) and increased according to the grade of lung cancer stage in peripheral blood ( p < 0.0001). Western blot results confirmed the presence of the LESP1 with higher intensity band at each grade of lung cancer stage than healthy controls. Interestingly, we found that the number of GFP+ exosomes was decreased and cell migration was inhibited when the LESP1 was suppressed in NSCLC cells. Conclusions: The LESP-1 in exosomes was highly expressed in blood plasma of lung cancer patients, and the exosome release and cancer cell migration was inhibited by the LESP-1, which suggest that LESP-1 could be a feasible factor for diagnosis and treatment of non-small cell lung cancer.