Tumor-exosomal miR-205-5p as a diagnostic biomarker for colorectal cancer

Abstract Background: Tumor-exosomal miRNA play crucial roles in cancer diagnosis. The current reports aimed to found an exosomal miRNA for colorectal cancer(CRC) with non-invasiveness, sensitivity and specificity. Patients and methods: The exosome was extracted from CRC patients and healthy donors using ultracentrifugation to verify by TEM, qNano and western blot. Differential expression level and clinical characterization of miR-205-5p were analyzed in colorectal cancer via TCGA. Real Time Quantitative PCR was employed to determine the different expression levels of exosomal miRNAs in 157 primary CRC patients and 135 healthy donors. Predictions were made concerning target genes to determine the direction for further exploring the etiopathogenesis of the disease by means of bioinformatics. Results: The expression of miR-205-5p demonstrated a substantial downregulation in colorectal cancer compared to healthy donors, as determined through analysis of the TCGA database. We conducted a prediction and analysis of the functional enrichment of downstream target genes regulated by miR-205-5p. Reduced level of exosomal miR-205-5p in serum from CRC patients was found compared with healthy controls (p<0.0001, respectively) and benign disease (p<0.0001, respectively). The levels of expression of exosomal miR-205-5p were substantially lower in early stage CRC patients than in the contrast groups (p<0.0001, respectively). The expression levels of exosomal miR-205-5p saw significant increase postoperatively (p=0.0053, respectively). Conclusions: The present study demonstrated that serum exosomal miR-205-5p may be a diagnostic biomarker for colorectal cancer.