Bufadienolides from Venenum Bufonis Inhibit mTOR-Mediated Cyclin D1 and Retinoblastoma Protein Leading to Arrest of Cell Cycle in Cancer Cells

Figure 5

Bufadienolides inhibit mTOR pathway by a concentration-dependent manner. Serum-free cultured MCF-7 (a) and DU145 (d) cells were pretreated with bufadienolides (0-10 μg/ml) for 2 h, then stimulated with IGF-1 (10 ng/ml) for 1 h, and finally subjected to western blotting analysis with indicated antibodies. (b, c) Densitometry analysis of p-mTOR, p-S6K1, and p-4E-BP1 bands in MCF-7 cells was normalized to β-tubulin using ImageJ, expressed as arbitrary units versus IGF-1(10 ng/ml), a: p<0.01.