Figure 5

Suppressing manganese superoxide disumutase (MnSOD) expression by small-interfering RNA (siRNA) sensitises SKOV-3 cells to doxorubicin (DOX)- and paclitaxel (PTX)-induced apoptosis. Cells were exposed to DOX (5 μ M) or PTX (0.1 μ M) for 48 h and then harvested for (A) 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The absorbance of wells not exposed to treatments was arbitrarily set as 1, and cell growth after treatment was expressed as the fold changes compared with the control. Apoptosis was measured by (B) terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) assay and (C) by staining with FITC-annexin V and propidium iodide (PI) and analysed by flow cytometry. The per cent of apoptotic cells defined as annexin V⁺/PI⁻ (lower right quadrant) were counted. Experiments were repeated three times, and data are shown as mean±s.d. ^*P<0.05, ^**P<0.001 vs untransfected and Ctrl siRNA cells.