Clinical response and prognostic significance of serum miR-497 expression in colorectal cancer

BACKGROUND: Colorectal cancer (CRC) is a common type of cancer around the world. Detection of microRNA (miRNA) aberration in blood samples is a novel approach for CRC screening. OBJECTIVE: The purpose of this study was to explore the serum miR-497 expression pattern in CRC and examine its potential usefulness as a biomarker for CRC diagnosis and prognosis. METHODS: Serum miR-497 expression was evaluated by quantitative reverse transcription polymerase chain reaction (qRT-PCR) in 110 patients with CRC, 35 cases with colorectal adenoma, 54 cases with colorectal polyps, and 70 healthy individuals. RESULTS: The expression level of miR-497 was significantly down regulated in CRC tissues compared to the normal tissues based on the data from three independent studies GSE68204, GSE41655 and GSE35834. Compared to healthy controls, the serum miR-497 level was significantly decreased in patient with CRC or benign lesion (colorectal adenoma and polyps). Serum miR-497 level was dramatically increased in the post-operative blood samples from early stage CRC patients. Receiver-operating characteristic (ROC) analysis showed that serum miR-497 had a high sensitivity and specificity for discriminating CRC or precancerous colorectal lesion from normal controls. Moreover, low serum miR-497 expression was closely correlated with aggressive clinical features and shorter overall survival (OS). Kaplan-Meier analyses also revealed that OS was strongly associated with lymph node invasion, TNM stage and histological grade. Furthermore, univariate and multivariate analysis showed serum miR-497 was an independent prognostic factor for CRC. CONCLUSIONS: Collectively, serum miR-497 may serve as a promising biomarker for diagnosis and prognosis of CRC.