Exosomal circRNAs as novel potential biomarkers for colorectal adenoma

Growing evidences have revealed that exosomal miRNAs, lncRNAs, and circRNAs play a pleiotropic role in tumor biology. Cell-cell communication mediated by exosomes has been considered to be a key factor in the malignant progression of colorectal cancer. However, the importance of exosome-derived circRNAs in the biological function and clinical significance of colorectal adenoma remains elusive. In this study, we aimed to identify altered circRNA expression profiles in exosomes isolated from plasma of patients with colorectal adenoma using high-throughput sequencing. Exosomes were confirmed by western blotting, transmission electron microscopy, and NanoSight assay. The sequencing data indicated that there are 413 differentially expressed circRNAs including 112 upregulated and 301 downregulated circRNAs in colorectal adenoma patients compared with controls. GO analysis and the circRNA-miRNA-mRNA network were performed to predict the potential function of circRNAs, and demonstrate the putative mechanisms in colorectal adenoma. Collectively, our findings revealed that plasma exosomal circRNAs may be a potential noninvasive biomarker for the detection of colorectal adenoma, and provided new insights into colorectal adenoma-carcinoma sequence.