Fig. 1: Dioscin inhibits proliferation and induces apoptotic cell death in osteosarcoma cells.

a Chemical structure of dioscin. b, c Dioscin inhibits osteosarcoma cell (U2OS, U2OS/MTX300, HOS, MNNGHOS, 143B, MG63, ZOS, ZOSM, SJSA1, G292) viability in a dose-dependent manner. Osteosarcoma cells were treated with various concentrations of dioscin for 72 h, and the viability of cells was measured by the MTT assay. And the IC50 were calculated and shown. d Dioscin reduces colony formation of osteosarcoma cells. Colony-formation ability of osteosarcoma cells (U2OS, U2OS/MTX300, ZOS, 143B) was examined after dioscin treatment for 10 days. e Dioscin induces a G2/M phase arrest in osteosarcoma cells (U2OS, 143B). Cell-cycle distribution of osteosarcoma cells treated with vehicle or 2.5 μm dioscin for 24 h was detected and analyzed by flow cytometry. f, g Dioscin upregulates the expression of P21 at both mRNA and protein levels detected by qRT-PCR and western blot, respectively. h Annexin V/PI staining of osteosarcoma cells (U2OS, 143B) treated with vehicle or 2.5 μm dioscin for 48 h was detected and analyzed by flow cytometry. i Several apoptosis indexes (cleaved PARP, Bcl-2 and Bcl-xL) were detected by western blot. Dioscin induces cleavage of PARP as well as downregulation of Bcl-2 and Bcl-xL. j Hoechst staining showed brighter blue staining and typical morphological changes of apoptosis including the reduction of nuclear size and chromatin condensation in nuclear chromatin of U2OS and 143B cells after 2.5 μm dioscin treatment for 24 h. Scale bar, 100 μm. Data represent the mean ± SD of three independent experiments. **p < 0.01, ***p < 0.001 by two-tailed Student’s t test, SPSS 20.0