Diagnostic Value Investigation and Bioinformatics Analysis ofmiR-31 in Patients with Lymph Node Metastasis ofColorectal Cancer

Colorectal cancer (CRC) is one of the most frequent cancers occurring in developed countries. Distant CRC metastasis causes morethan 90% of CRC-associated mortality. MicroRNAs (miRNAs) play a key role in regulating tumor metastasis and could be potentialdiagnostic biomarkers in CRC patients. This study is aimed at identifying miRNAs that can be used as diagnostic biomarkers forCRC metastasis. Towards this goal, we compared the expression offive miRNAs commonly associated with metastasis (i.e., miR-10b, miR-200c, miR-155, miR-21, and miR-31) between primary CRC (pCRC) tissues and corresponding metastatic lymph nodes(mCRC). Further, bioinformatics analysis of miR-31 was performed to predict target genes and related signaling pathways. Resultsshowed that miR-31, miR-21, miR-10b, and miR-155 expression was increased to different extents, while miR-200c expression waslower in mCRC than that in pCRC. Moreover, we found that the level of both miR-31 and miR-21 was notably increased in pCRCwhen lymph node metastasis (LNM) was present, and the increase of miR-31 expression was more profound. Hence, upregulatedmiR-31 and miR-21 expression might be a miRNA signature in CRC metastasis. Moreover, we detected a higher miR-31 level in theplasma of CRC patients with LNM compared to patients without LNM or healthy individuals. With the bioinformatics analysis ofmiR-31, 121 putative target genes and transition of mitotic cell cycle and Wnt signaling pathway were identified to possibly play arole in CRC progression. We next identified seven hub genes via module analysis; of these, TNS1 was most likely to be the target ofmiR-31 and had significant prognostic value for CRC patients. In conclusion, miR-31 is significantly increased in the cancer tissuesand plasma of CRC patients with LNM; thus, a high level of miR-31 in the plasma is a potential biomarker for the diagnosis of LNMof CRC.