circANKS1B regulates FOXM1 expression and promotes cell migration and invasion by functioning as a sponge of the miR-149 in colorectal cancer

Background: Circular RNAs (circRNAs) and microRNAs (miRNAs) play key roles in the development of human cancers. CircANKS1B has been reported to be increased in breast cancer. Methods: Real-time polymerase chain reaction (real-time PCR) assay was used to measure expressions of circANKS1B, ANKS1B, and FOXM1. Western blot assay was employed to examine the protein level of FOXM1 and Slug. The abilities of cell migration and invasion were measured by wound-healing and transwell assays. The interaction between circANKS1B and miR-149 was confirmed by site-directed mutagenesis and luciferase assays. Results: The expression of circANKS1B was up-regulated in colorectal cancer tissues and cells. Additionally, circANKS1B increased the expression of FOXM1. Furthermore, the enhancement of CRC cell migration and invasion by circANKS1B was dependent on FOXM1. However, previous studies have shown that miR-149 can directly target FOXM1 and act as tumor suppressor in CRC. Consequently, our results showed that miR-149 could directly bind to circANKS1B and FOXM1. The inhibition of circANKS1B could reduce FOXM1 and Slug protein levels, thus suppressing CRC cell migration and invasion. Conclusion: Taken together, circANKS1B promotes colorectal cancer cell migration and invasion by acting as a molecular sponge of miR-149 to modulate FOXM1 and Slug protein levels.