Global and targeted circulating microRNA profiling of colorectal adenoma and colorectal cancer

BACKGROUND: Circulating microRNAs (miRNAs) are emerging as promising biomarkers for cancer. The objective of the current study was to investigate the potential of circulating cell-free miRNAs as biomarkers for colorectal cancer (CRC) and its precursor lesion, colorectal adenoma. METHODS: The serum levels of 800 miRNAs were assessed in a discovery set of 21 patients with CRC, 19 patients with adenoma, and 21 healthy controls using the NanoString miRNA analysis platform. Significantly differentially expressed miRNAs were examined further in a validation cohort of 34 patients with CRC, 33 patients with adenoma, and 35 healthy controls using Fluidigm quantitative polymerase chain reaction assays. RESULTS: The ratios between the expression values of the differentially expressed miRNAs were computed. Three miRNA ratios (miR-17-5p/miR-135b, miR-92a-3p/miR135b, and miR-451a/miR-491-5p) were validated for discriminating patients with adenoma and those with CRC from the healthy control group, and 5 miRNA ratios (let-7b/miR-367-3p, miR-130a-3p/miR-409-3p, miR-148-3p/miR-27b, miR-148a-3p/miR-409-3p, and miR-21-5p/miR-367-3p) were validated for discriminating patients with CRC from those with adenoma and healthy controls. The area under the receiver operating characteristic curve values for the 3 miRNA ratios in discriminating patients with adenoma from healthy controls were 0.831 and 0.735, respectively, in the discovery and validation sets. The area under the receiver operating characteristic curve values for the 5 miRNA ratios in discriminating patients with CRC from those with adenoma were 0.797 and 0.732, respectively, in the discovery and validation sets. Pathway analysis revealed that target genes regulated by the miRNAs from the miRNA ratios were enriched mainly in metabolism-related and inflammation-related pathways. CONCLUSIONS: The data from the current study suggest that circulating miRNAs can distinguish patients with CRC and those with adenoma and may represent novel biomarkers for the early, noninvasive detection of CRC. Cancer 2018;124:785-96.