Investigation of microRNA-155 as a serum diagnostic and prognostic biomarker for colorectal cancer.

The aim of the present study was to explore serum microRNA-155 (miR-155) expression in patients with colorectal cancer (CRC) and examined the potential usefulness of this molecule as a biomarker for diagnosis and prognosis in CRC. Serum samples were obtained between May 2007 and March 2013 from 146 CRC patients and 60 healthy controls. Serum miR-155 expression levels were measured by quantitative real time reverse transcription-polymerase chain reaction (qRT-PCR). Survival curves were obtained using the Kaplan-Meier method and assessed by the log-rank test. The receiver operating characteristic (ROC) curve was used for the prediction of cut-off values of the markers. Serum miR-155 expression level on average was upregulated in CRC patients compared with the matched healthy controls (P < 0.001). ROC curve analysis showed that miR-155 was a useful marker for discriminating cases from healthy controls, with an area under the ROC curve (AUC) of 0.776 (95% confidence interval (CI) 0.714 to 0.837, P < 0.001). Kaplan-Meier analysis with the log-rank test indicated that high serum miR-155 expression had a significant impact on overall survival (38.2 vs. 69.9%; P < 0.001) and progression-free survival (34.8 vs. 66.0%; P < 0.001). In conclusion, the detection of miR-155 levels in the serum might serve as a new tumor biomarker in the diagnosis and assessment of prognosis of CRC.