HSP90 Inhibitors, Geldanamycin and Radicicol, Enhance Fisetin-Induced Cytotoxicity via Induction of Apoptosis in Human Colonic Cancer Cells
Figure 1
Effects of geldanamycin (GA) and radicicol (RAD) on the viability of COLO205 colorectal carcinoma cells under fisetin (FIS) stimulation. (a) The chemical structures of FIS and the structurally related robinetin (ROB) are depicted. (b) FIS reduction of cell viability of COLO205 cells. COLO205 cells were treated with the indicated concentrations (30, 60, and 120 μM) of FIS for 24 h, and cell viability was examined by an MTT assay. (c) DNA ladders induced by FIS or ROB (60 or 120 μM) in COLO205 cells were detected by agarose electrophoresis. (d) GA enhanced DNA ladder formation in COLO205 cells stimulated by FIS. (Left panel) cells were treated with different concentrations of GA (0.5, 1, and 2 μM) with or without FIS (120 μM) stimulation for 24 h. (Right panel) cells were treated with GA (2 μM) with or without FIS (30 or 60 μM) stimulation for 24 h. The integrity of DNA was analyzed by agarose electrophoresis. (e) GA increased the cytotoxicity of FIS against the viability of COLO205 cells. Cells were treated with GA (2 μM) and FIS (60 or 120 μM) for 24 h, and the viability of cells was examined by an MTT assay. (f) Increases in the percentage of hypodiploid cells by GA in FIS-treated COLO205 cells. As described above, the ratio of hypodiploid cells under different treatments was examined by a flow cytometric analysis using propidium iodide (PI) staining. (g) RAD addition increased the intensity of DNA ladder formation in FIS-treated COLOL205 cells. Cells were treated with different concentrations (2.5, 5, and 10 μM) of RAD with FIS (60 μM) for 24 h, and the integrity of DNA was analyzed. Each data point was calculated from three triplicate groups, and data are displayed as the mean ± S.E. and denote a significant difference compared to the control (C) group (Figure 1(b)) or between the indicated groups (Figures 1(e) and 1(f)).
