Overexpression of circ-FOXO3 inhibits colorectal cancer cell proliferation, migration and invasion. (A) Circular characteristic of circ-FOXO3 was assessed using RNase R digestion assay. (B) Reverse transcription-quantitative PCR was used to detect the transfection efficiency of pcDNA circ-FOXO3 in HT29 and HCT116 cells. (C) Cell Counting Kit-8 assay measured the viability of HT29 and HCT116 cells after circ-FOXO3 overexpression. (D) Colony formation assay determined the colony formation ability of HT29 and HCT116 cells after overexpression of circ-FOXO3. Transwell migration assay detected the (E) migratory and (F) invasive abilities of cells after overexpression of circ-FOXO3. Magnification, ×100; Scale bar, 100 µm. (G) Western blotting was conducted to detect the protein expression levels of E-cadherin, N-cadherin, Vimentin and MMP9 in HT29 and HCT116 cells after overexpression of circ-FOXO3. All experiments were performed three times. *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001 vs. Vector group. circ-FOXO3, circular RNA FOXO3; OD, optical density.