WITHDRAWN: GCC2 is a New Biomarker for Diagnosis of Early Non-Small Cell Lung Cancer and A Potential Target to Reverse Epithelial to Mesenchymal Transition

Abstract

Background: Nano-sized exosomes (30–150 nm) are cell membrane-encapsulated vesicles that contain nucleic acids and proteins. Specific markers detecting non-small cell lung cancer (NSCLC) cell-derived exosomes in the blood circulation remain unidentified. Here, we report a new biomarker distinguishing cancer from non-cancer exosomes that also involved in epithelial to mesenchymal transition for cancer treatment.Methods: Exosomes were isolated from plasma of patients with various pathological stages of NSCLC and NSCLC cell lines, human pulmonary alveolar epithelial cells by size exclusion chromatography and characterized by Nanoparticle Tracking Analysis and western-blotting. The exosomes were lysed and applied to proteomic analysis. The expression levels of the GCC2 proteins from NSCLC patients were analyzed by ELISA assays, and the effects by GCC2 shRNA were analyzed by real-time RT-PCR, cell migration and colony formation assays.Results: A protein GRIP and coiled-coil domain-containing 2 (GCC2), which is involved in endosome-to-Golgi transport, was identified by the proteomics analysis of exosomes isolated from NSCLC cell lines. The GCC2 protein expression levels were increased in the exosomes derived from patients with early-stage NSCLC compared with healthy controls. The receiver operating characteristic curve of exosomal GCC2 revealed 94.74% sensitivity and 75.00% specificity, and AUC of 0.875. GCC2 knockdown experiments by GCC2 shRNA showed reduced exosome secretion in cancer cell lines, which altered the molecular and cellular properties, such as the expression levels of mesenchymal-to-epithelial genes, and cellular growth and motility.Conclusion: GCC2 represents a promising biomarker for early diagnosis of NSCLC and a therapeutic target for future cancer treatment.