miR-196a-5p promotes metastasis of colorectal cancer via targeting IκBα

Background: MicroRNA-196a-5p (miR-196a-5p) has been reported to be involved in the metastatic process of several cancers. In present work, we aimed to investigate the effects of miR-196a-5p and its potential target IκBα on migration, invasion and epithelial-mesenchymal transition (EMT) of colorectal Cancer (CRC) cells.

Methods: CCK-8 assay, wound healing assay and cell invasion assay were performed to evaluate the cell proliferation, migration and invasion. In vivo metastasis models were used to investigate the tumor metastasis ability. Real-Time PCR, immunofluorescence staining or western blot were utilized to detect the expression of miR-196a-5p, IκBα, p-IκBα, nuclear p65 and EMT markers including E-cadherin, N-Cadherin and fibronectin. Dual luciferase reporter assay was carried out to determine whether there is a direct interaction between miR-196a-5p and IκBα mRNA.

Results: Using SW480 cell with miR-196-5p over-expressed plus SW620 and HCT116 cells with miR-196a-5p knockdown, we found that miR-196a-5p promoted cell proliferation, migration and invasion in vitro and facilitated liver metastasis in vivo. We also observed that miR-196a-5p knockdown or NF-κB pathway inhibition up-regulated E-cadherin while down-regulated N-Cadherin and fibronectin. By contrast, miR-196a-5p over-expression promoted EMT process of CRC. Data of dual luciferase reporter assay indicated that miR-196a-5p targeted the IκBα. Moreover, miR-196a-5p down-regulated IκBα expression while up-regulated nuclear p65 expression. Additionally, over-expression of IκBα in CRC cells attenuated the effects of miR-196a-5p on cell migration, invasion and EMT.

Conclusions: miR-196a-5p may play a key role in EMT, invasion and metastasis of CRC cells via targeting the IκBα.