MicroRNA-222 influences migration and invasion through MIA3 in colorectal cancer

Background: miR-222 has been reported to be overexpressed in colorectal cancer and it influences cancer cell proliferation, drug resistance and metastasis. However, the underlying molecular mechanism of miR-222 in colorectal cancer cell invasion and migration has not been thoroughly elucidated to date. Methods: The cell cycle distribution and apoptosis were assessed by flow cytometry. Cell migration and invasion were analyzed by Transwell assays. The possible target gene of miR-222 was searched and identified by bioinformatics, dual luciferase reporter assay and western blot analysis. The siRNA method was used to confirm the function of the target gene. Results: Overexpression of miR-222 effectively promotes migration and invasion of colorectal cancer (CRC) cells in vitro. Bioinformatics and the dual luciferase reporter assay revealed that miR-222 specifically targeted the 3'-UTR of melanoma inhibitory activity member 3 (MIA3), down-regulating its expression at the protein level. Inhibition of MIA3 by siRNA enhanced the migration and invasion of CRC cell lines. Conclusions: Our study showed that miR-222 enhances the migration and invasion in CRC cells, primarily by down-regulation of MIA3.