Figure 2.

miR-17/20 arrests cell cycle at the G₁ phase in a cyclin D1–dependent manner. (A) Western blot analysis of the cyclin D1, CDK4, CDK6, and cyclin E expression in miR-17/20–transduced cells. GDI served as loading control. (B) MCF-7 cells were transfected with cyclin D1 siRNA and control siRNA. Western blotting demonstrated the efficient knockdown of cyclin D1 after 72 h of siRNA treatment. (C) Cell cycle analysis indicated the increased population of cells at G₀/G₁ phase and decreased S and G₂/M phase cells in miR-17/20–transduced MCF-7 cells under a cyclin D1 background. This difference was abolished by knockdown of cyclin D1 in cells. The analysis was performed in triplicates (data are equal to mean ± SEM). (D) Northern blot demonstrated the increased expression of miR-17/20 in the miR-17/20–transduced NAFA cells. tRNA served as a loading control. (E) The MTT assay showed the inhibited cell proliferation of NAFA cells by miR-17/20 transduction. The assay was performed in three independent experiments, and the data are presented as the mean ± SEM.