Downregulation of MicroRNA-449 Promotes Migration and Invasion of Breast Cancer Cells by Targeting Tumor Protein D52 (TPD52)

Our study aimed to investigate whether microRNA-449 (miR-449) plays a key role in regulating the migration and invasion of breast cancer cells via targeting tumor protein D52 (TPD52). The results of the qRT-PCR and Western blotting showed that, in comparison with normal breast tissues and cells, miR-449 was significantly downregulated in breast cancer tissues and cells, while TPD52 was markedly upregulated. After transfection with an miR-449 inhibitor, suppression of miR-449 significantly promoted cell migration and invasion. Also, when miR-449 was overexpressed by transfection with miR-449 mimics, E-cadherin expression significantly increased, and the expression of N-cadherin and vimentin were markedly decreased, whereas the opposite effects were obtained when miR-449 was suppressed by transfection with an miR-449 inhibitor. TPD52 was also confirmed as the direct target of miR-449 via luciferase reporter analysis. Knockdown of TPD52 significantly alleviated the effects of miR-449 overexpression on cell migration and invasion, as well as the expression of E-cadherin, N-cadherin, and vimentin. Our results indicate that downregulation of miR-449 may promote the migration and invasion of breast cancer cells by targeting TPD52. miR-449 may serve as a potential target in the therapy of breast cancer.