Xiangxiang Liu, Tao Xu, Xiuxiu Hu, XiaoXiang Chen, Kaixuan Zeng, Li Sun, Shukui Wang

Globally, colorectal cancer (CRC) is one of the most common cancers with high mortality. Although CRC patients in stages I-II are curable after surgical resection, due to the lack of sensitive and specific biomarkers, many patients are in the advanced stages when diagnosed. This study aimed to investigate whether circulating miRNAs in plasma could act as biomarkers for early CRC diagnosis. All healthy subjects and patients were from Nanjing First Hospital. We first selected 2 differential miRNAs by integrated analysis of 4 Gene Expression Omnibus (GEO) data sets and The Cancer Genome Atlas (TCGA) database. Next, the expression of these 2 miRNAs in tissue and plasma samples were examined through quantitative real-time polymerase chain reaction. Training phase and validation phase were designed to investigate the diagnostic utility of these differential miRNAs using receiver operating characteristic (ROC) curve analysis. After integrated analysis of 4 GEO and TCGA databases, upregulated miR-182 and miR-20a were selected to further investigate their diagnostic potential for CRC. We discovered that miR-182 and miR-20a were upregulated in CRC tissue and plasma and that circulating miR-182 and miR-20a in the plasma of CRC patients were tumor derived. The area under the ROC curve (AUC) of circulating miR-182 was 0.929 (95% CI 0.875-0.983) in the training phase and 0.891 (95% CI 0.821-0.961) in the validation phase. The AUC of circulating miR-20a expression was 0.801 (95% CI 0.695-0.906) in the training phase and 0.736 (95% CI 0.631-0.842) in the validation phase. Circulating miR-182 is a novel potential biomarker for early CRC diagnosis.