Objective   To investigate whether miR-206 can regulate Cdc42 protein expression and cytoskeleton remodeling.    Methods   miR-206 was transfected into MDA-MB-231 cells using Lipofectamine

TM

2000

and the transfected cells were harvested in 48 h. Western blot analysis was used to detect the protein expressions of Cdc42

MMP-2 and MMP-9. Actin-Tracker Green was used to stai

n F-actin and filopodia was observed by fluorescent microscopy. Invasion assay and Transwell migration assay were taken to examine the invasive and migratory ability of cells before and after the transfection respectively.    Results   Protein expressions of Cdc42

MMP-2 and MMP-9 were all down-regulated (P0.01). The number of filopodia per cell in the blank group (untransfected group) was 14.99±5.53

in EGF group was 23.59±3.92

miR-206 group was （9.45±3.59）

and miR-206+EGF group was 11.77±2.85. The filopodia numbers in miR-206 and miR206+EGF groups was much less than those in the blank group and EGF group (P0.05). The invasion and migration of miR-206 transfected MDA-MB-231 cells (65.0±13.9) were significantly lower than MDA-MB-231 cells [blank control

311.7±23.5

P0.05

]

; Transwell migratory assay indicated that there were more migrated cells in blank control group than in miR-206 group [793.0±76.3 vs 415.3±20.0

P0.05

]

.    Conclusion   miR-206 downregulates Cdc42 protein expression in MDA-MB-231 cells

inhibits the formation of filopodia

and thus inhibits the invasion and migration efficiency of the cells.