FIGURE 1.
High levels of let-7 results in reduced cell proliferation and G2/M arrest in asynchronously and synchronously dividing fibroblasts, whereas anti-let-7 results in increased proliferation. A and B, primary fibroblasts transfected with a negative control (NC) pre-miR, pre-let-7b, or pre-let-7c were monitored using Alamar blue at the indicated time points after transfection. The asterisks indicate statistical significance as compared with the negative control pre-miR. (*, = p < 0.05; **, = p < 0.01; ***, = p < 0.001). A, the addition of pre-let-7b or pre-let-7c resulted in fewer cells in asynchronously dividing primary fibroblasts at 72 and 96 h after transfection. B, cells were monitored at 24 h after transfection, at 36 h after serum withdrawal, then at 12, 24, and 36 h after serum stimulation. Transfection of let-7b or let-7c as compared with a negative control pre-miR resulted in fewer cells at 24 and 36 h after stimulation. C and D, cell cycle analysis of asynchronous (C) or synchronized (D) cells. An increase in the number of cells in the G2/M phase of the cell cycle was observed, which reached statistical significance in cells 24 and 36 h after serum stimulation. E, primary fibroblasts transfected with an anti-miR control or anti-let-7b were monitored with Alamar blue. Asterisks are as indicated in A and B. In synchronized cells, increased cell number was observed at 24 and 36 h after serum stimulation.