The inhibitory effect of miR-99a mimics on human breast cancer cells.

(A) Cell viability MTT assay. The cell viability curve was constructed consecutively for up to 72 h after transfection of MCF-7 and MDA-MB-231 cells with Lipofectamine 2000 only (MOCK), scrambled negative control (NC) and miR-99a mimics. (B) Flow cytometry analysis of cell cycle. At 72 h post-transfection, MCF-7 and MDA-MB-231 cell lines treated with miR-99a mimics showed a remarkable increased sub-G1 phase population compared with MOCK and NC groups. (C) Flow cytometry analysis of apoptosis. After 72 h treatment, transfection of miR-99a mimics into MCF-7 and MDA-MB-231 cell lines resulted in a significant increase percentage of apoptotic cells compared with the control. (D) The tumors shown are from the final time point (30_day). Xenograft sizes from six representative nude mice from three treatment groups (MDA-MB-231 cells with CMV-miR-99a, CMV-NC and MOCK). (E) The xenograft growth analysis after breast cancer cell inoculation. The average size of the tumors was measured every 5 days and shown in the curves (P<0.05 compared to the control cells).