Serum Exosomal MicroRNA-31 Serves as a Potential Biomarker for Colorectal Cancer and Colorectal Adenomatous Polyps

Background: Although developing serum microRNAs (miRNAs) as noninvasive diagnostic biomarkers for the identification of colorectal adenomatous polyps (CAP) and early-stage colorectal cancer (CRC) is more promising, CAP and CRC serum exosomes miRNAs have more research values. This study was designed to assess the diagnostic and prognostic values of serum exosomal candidate miRNAs as biomarkers of CAP and CRC.Methods: Serum and serum exosomes were obtained from 60 CRC patients, 60 CAP patients and 60 healthy controls (HC). Then, the expression of miR-21, miR-31, miR-135b, miR-145 in serum and serum exosomes as well as serum exosomal miR31 and miR-145 expression in subjects 1 month after surgery was detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The correlation of clinicopathological features of CRC with the serum exosomal miR-31 and miR145 expression was analyzed, and the independent predictors of CRC were analyzed by univariate logistic regression. Receiver operating characteristic (ROC) curves were adopted to examine the diagnostic accuracy of serum exosomal miR-31 and miR-145. Results: CAP and CRC patients had elevated serum exosomal miR-31 expression but declined miR-145 expression. The serum exosomal miR-31 and miR-145 expression was affected by tumor diameter, degree of differentiation, TNM (tumor node metastasis) staging, distant metastasis, and lymphatic metastasis. Serum exosomal miR-31 was more specific and sensitive as a diagnostic and prognostic biomarker for CAP and CRC compared with miR-145.Conclusions: Therefore, compared with serum exosomal miR-145, serum exosomal miR-31 is a superior diagnostic biomarker for the diagnosis of CAP and CRC.