Real-time quantitative miRNA PCR analysis of human plasma samples; circulating miRNAs miR-34a and miR-150 associated with colorectal cancer progression

Background: Screening for the early detection of colorectal cancer is important to improve patient survival. The aim of this study was to investigate the potential of circulating cell-free miRNAs as biomarkers of CRC, and their efficiency at delineating patients with polyps and benign adenomas from normal and cancer patient groups. Methods: The expression of 667 miRNAs was assessed in a discovery set of 48 plasma samples comprising normal, polyp, adenoma, and early and advanced cancer samples. Three miRNAs (miR-34a, miR-150, and miR-923) were further examined in a validation cohort of 97 subjects divided into the same five groups, and in an independent public dataset of 40 CRC samples and paired normal tissues. Results: High levels of circulating miR-34a and low miR-150 levels distinguished groups of patients with polyps from those with advanced cancer (AUC=0.904), and low circulating miR-150 levels separated patients with adenomas from those with advanced cancer (AUC=0.875). In addition, the altered expression of miR-34a and miR-150 in an independent public dataset of forty CRC samples and paired normal tissues was confirmed. Conclusion: We identified two circulating miRNAs capable of distinguishing patient groups with different diseases of the colon from each other, and patients with advanced cancer from benign disease groups. qPCR miRNA expression profiling. Plasma samples from 48 donors comprising 8 normal, 8 polyp, 16 adenoma samples, 8 early stage cancer samples (stage I/II), and 8 advanced cancer samples (stage III/IV) were used. RNA was extracted from equal volumes of plasma from each donor.