Figure 4.

Overexpression of miR-224 enhances the proliferation and tumorigenicity of OS cells in vitro and in vivo. (a) Cell MTT assay. Overexpression or knockdown of miR-224 by miR-224 mimics or inhibitors affected the cell proliferation of MG-63 and U2OS cells. Data are presented as mean±S.D. (n=6). (b) Flow cytometric analysis of cell apoptosis rate. The apoptosis rate of miR-224-knockdown U2OS and MG63 cells increased significantly, compared with control cells. (c and d). Transwell migration (c) and invasion (d) assays showed that the miR-224 inhibitor suppressed the migration and invasion abilities of U2OS and MG-63 cells. (e) U2OS and MG-63 cells transfected with the negative control (NC) or miR-224 inhibitor were cultured in soft agar for 20 days. Colonies were stained with crystal violet, photographed and quantified with ImageJ (details are shown in the inserts). (f) Inhibition of miR-224 repressed cell growth, as determined by colony formation assays. Error bars represent the mean±S.D. from three independent experiments; *P<0.01. (g) Control or miR-224-inhibited MG-63 cells were injected into each group. Inset shows miR-224 expression in tumors from control or miR-224 sponge cells. Photograph of representative mice inoculated with the negative control or miR-224 sponge-expressing cells in the left or right dorsal area, respectively (n=4, mean±S.D., *P<0.01)