Investigating JUNB and CXCR4 expression in Circulating Tumor Cells and exosomes derived from Small Cell Lung Cancer (SCLC) patients
The enhanced metastatic ability of small-cell lung cancer warrants the discovery of prognostic biomarkers to support decisions during the course of the disease. We have previously demonstrated the clinical significance of JUNB and CXCR4 expression in circulating tumor cells (CTCs) from breast and non-small cell lung cancer (NSCLC). patients. In the present study, we aimed to explore the expression levels of the aforementioned biomarkers in patients' CTCs and plasma-derived exosomes. One hundred SCLC patients at baseline were enrolled in the study; exosome isolation was performed in 58 of them. Cytospins were analyzed using the VyCAP system and exosomes were characterized based on their molecular and transcriptomic profile. JUNB and CXCR4 were expressed in the majority of the CTCs. Protein exosomal expression of both biomarkers in patients was significantly different compared to healthy donors (p = 0.003 and p = 0.027, respectively), while a high discriminative ability was observed in patients overexpressing JUNB and CXCR4 in their exosomes (c-statistic = 0.949 and c-statistic = 0.903 respectively). The presence of JUNB and/or CXCR4 in CTCs was associated with poorer OS (p = 0.025). CXCR4 exosomal overexpression correlated with the presence of CTCs and their phenotypes. Lastly, miRNA profiling on 4 SCLC patients, indicated a multitude of biological processes and signaling pathways implicated in SCLC pathogenesis. Our study is the first attempt to evaluate two different aspects of liquid biopsy (CTCs and exosomes) in SCLC patients, regarding JUNB and CXCR4 expression, aiming to provide a potential new prognostic and/ or diagnostic approach. Overall design: miRNA-seq on the Ion Torrent Genestudio S5 platform with Ion Chef (Ion torrent) on plasma-derived exosome from one healthy donor and four Small Cell Lung Cancer (SCLC) patients