Colorectal cancer (CRC) is a highly invasive tumor that is frequently associated with distant metastasis, which is the primary cause of poor prognosis. However, the mechanisms of metastasis remain poorly understood. MicroRNAs (miRNAs/miRs) have been considered to be implicated in CRC progression. In particular, miR-517a is proposed as a novel tumor-associated miRNA and has a potential role in tumor metastasis. The expression of miR-517a in CRC specimens was detected by reverse transcription-quantitative polymerase chain reaction. Transwell assays were performed to determine the migration and invasion of CRC cells. The putative target genes of miR-517a were disclosed using publicly available databases and western blot analysis. The present study identified that the expression of miR-517a was significantly higher in CRC tissues as compared with adjacent non-tumor tissues. Clinical analysis indicated that increased expression of miR-517a was correlated with poor prognostic features and poor long-term survival of CRC patients. In vitro evidences demonstrated that downregulation of miR-517a inhibited cell migration and invasion in HCT-116 cells. By contrast, upregulation of miR-517a increased the number of migrated and invaded SW480 cells. Notably, miR-517a expression was inversely regulated by forkhead box J3 (FOXJ3) abundance in CRC cells. Furthermore, an inverse correlation between miR-517a and FOXJ3 expression was observed in CRC tissues. In conclusion, miR-517a appears to be an independent prognostic marker for predicting survival of CRC patients, and may promote cell migration and invasion by inhibiting FOXJ3.
Keywords: colorectal cancer; invasion; miR-517a; migration; prognostic marker.