Objective To investigate the effect of miRNA-101 (miR-101) on the invasion and Wnt/β-catenin pathway activation in colon cancer cells through targeting CDK8.

Methods qRT-PCR and Western blot were used to detect the expression of miR-101 and CDK8 in colon cancer tissues, adjacent normal tissues and five colon cancer cell lines. Dual luciferase reporter assay was used to determine whether miR-101 could directly bind to the 3'UTR region of CDK8. CDK8 expression was regulated through miR-101 mimic and/or pBabe-CDK8 transfection, and its effects on tumor cell invasion and Wnt/β-catenin activation were detected.

Results Compared with adjacent normal tissues, the expression level of miR-101 in colon cancer tissues was significantly decreased, while the expression of CDK8 increased significantly. Dual luciferase reporter assay confirmed that miR-101 could bind directly to the 3'UTR region of CDK8 and regulate its expression. The invasion ability of colon cancer cells transfected with miR-101 mimic was significantly lower than those in negative control group and CDK8 overexpression group. The transfection of miR-101 mimic resulted in a significant decrease of TOP/FOP luciferase activity and β-catenin protein expression. However, CDK8 overexpression vector transfection could significantly inhibit the effect of miR-101 mimic.

Conclusion miRNA-101 could regulate colon cancer cell invasion and Wnt/β-catenin pathway activation through targeting CDK8.