The objective of this study was to identify the key circular RNAs (circRNAs) related to the development of colon cancer. High-throughput RNA sequencing on eight early-stage (ES) and eight later stage (LS) colon tumor tissues, and eight normal tissues, was performed. Differentially expressed circRNAs and differentially expressed mRNAs were identified. Functional enrichment analysis and the miRNA-circRNA-mRNA network were performed. In addition, the differential expression levels of key circRNAs were verified using real-time quantitative PCR (qPCR). In total, 408, 472, and 278 differentially expressed circRNAs were identified in ES versus normal control (N), LS versus N, and LS versus ES groups, respectively. Functional enrichment analysis showed that circ_052666 was significantly enriched in "extracellular matrix/receptor interaction"; circ_022743 was remarkably enriched in "neurotrophin signaling pathway"; and circ_004452 was observably enriched in "TGF-β signaling pathway." Moreover, key miRNA-circRNA-mRNA relationships, such as hsa-miR-29b/c-3p-circ_052666-COL1A1 and hsa-miR-1294-circ_004452-left-right determination factor 1 (LEFTY1), were identified. Furthermore, qPCR showed consistent results with RNA sequencing. Our findings indicate that key circRNAs, such as circ_022743, circ_052666, and circ_004452, may be involved in colon cancer development, and could be used as potential biomarkers for the diagnosis and treatment of this disease.
Keywords: colon cancer; differentially expressed circular RNAs; functional enrichment analysis; miRNA-circRNA-RNA network.