It has been demonstrated that there are abundant stable microRNAs (miRNAs) in plasma/serum, which can be detected and are potentially disease-specific. The aim of this study was to investigate whether plasma miR-200c and miR-18a can be used as biomarkers for the detection of colorectal carcinoma (CRC). This study was divided into three parts: i) confirmation of higher miR-200c and miR-18a levels in primary CRC tissues compared to normal colorectal tissues; ii) evaluation of plasma miR-200c and miR-18a expression by comparing 78 patients with 86 healthy volunteers and iii) comparison of miR-200c and miR-18a levels in paired pre-and post-operative plasma in cancer patients who underwent curative CRC resection. Results showed that the expression of miR-200c and miR-18a was significantly higher in CRC compared to normal tissues. The plasma levels of miR-200c and miR-18a were significantly higher in CRC patients compared to controls. miR-200c yielded an area under the receiver-operating characteristics (ROC) curve (AUC) of 0.749 and miR-18a yielded an AUC of 0.804 when distinguishing CRC patients from the controls. Combined ROC analyses using the two miRNAs revealed an elevated AUC of 0.839 with 84.6% sensitivity and 75.6% specificity in discriminating CRC. Plasma levels of miR-200c and miR-18a were significantly lower in post-operative compared to pre-operative samples. The results of this study suggest that plasma miR-200c and miR-18a are significantly elevated in the plasma of CRC patients and that they may serve as non-invasive molecular markers for CRC screening.
Keywords: biomarker; colorectal cancer; miR-18a; miR-200c; plasma.