Fig. 2

Silvestrol induces apoptosis in MDA-MB-435 cells. a Quantification of apoptosis was performed using DAPI staining. Apoptotic cells were identified by condensation and fragmentation of the nuclei. b Silvestrol induced apoptosis is time-dependent. MDA-MB-435 cells were treated with DMSO or 25 nM silvestrol for 24 to 72 h, and the Annexin V-FITC/PI double-staining analysis was performed. The early apoptosis (Annexin V-FITC positive, PI negative) and necrotic/late apoptotic (Annexin V-FITC positive, PI Positive) stages were quantified as apoptotic cells. c Cells in logarithmic growth were treated with DMSO, silvestrol, or vinblastine for 24 h or 48 h. Caspase 3/7 activity was assessed as production of a luminescent product. d Immunoblot analysis of caspase 3 and PARP. The cleavages of caspase 3 and PARP were detected in cells treated with DMSO, 1 nM vinblastine, 30 nM homoharringtonine (HHT) or silvestrol for the indicated times and harvested for protein analysis. Data presented as means ± SEM, * p ≤0.05