Bidirectional Regulation of Genistein on the Proliferation and Differentiation of C2C12 Myoblasts.

1. Genistein is a widely studied phytoestrogen. The effects of genistein on myoblasts were reported long ago, but the conclusions are controversial. In the current study, we evaluated the effects of different concentrations of genistein on C2C12 myoblasts. 2. Genistein treatment promoted myoblast proliferation in a dose-development manner in the 0-2 µM/L range, reaching its maximum effect at 2 µM/L. Proliferation then declined, and a concentration higher than 20 µM/L showed significant inhibition. Additionally, genistein treatment promoted myoblast differentiation at a dose of 10 µM/L. However, at treatment concentrations higher than 10 µM/L, the effect on myoblast differentiation was rapidly inhibited as the concentration increased. 3. Genistein treatment also downregulated miR-222, resulting in increased expression of its target genes, MyoG, MyoD and ERα and thereby promoting myoblast differentiation. 4. Our results suggest that genistein has a dose-dependent and bidirectional regulation effect on myoblast proliferation and differentiation. We also found that genistein is a miRNA inducer, and it specifically affects the expression of miR-222 to regulate myoblast differentiation.