Downregulation of serum miR-140-5p predicts poor prognosis of patients with colorectal cancer

MicroRNAs (miRNAs) have been demonstrated to play a central role in the initiation and development in many types of cancers including colorectal carcinoma (CRC). The purpose of current study was to investigate the clinical significance of serum miR-140-5p in CRC. Real-time PCR was performed to compare the expression level of miR-140-5p in the serum samples from 63 CRC patients, 20 patients with adenomas and 20 healthy controls. Then the clinical significance of serum miR-140-5p was further determined. Serum miR-140-5p was downregulated in the serum samples derived from CRC patients compared to patients with adenomas patients and controls (P<0.01). In addition, its expression level was able to discriminate CRC from adenomas as well as healthy controls with high accuracy, and was also significantly associated with various clinicopathological parameters including TNM stage (P = 0.0013) and lymph node metastasis (P = 0.0323). Serum miR-140-5p was remarkably upregulated in the patients who received surgery (P<0.01). Patients with lower serum miR-140-5p expression suffered poorer 5-year overall survival (P = 0.0034). In conclusion, our study revealed that serum miR-140-5p might function as a tumor suppressor in CRC, which might serve as a novel prognostic biomarker and therapeutic target.