Figure 1

Down-regulation of CK2 results in persistent γ-H2AX signal and reduced colony formation in human M059K glioblastoma cells. A. Cells were transfected with scramble siRNA (si-Scr), CK2α or -α'-siRNA for 72 hours. Where indicated, 0.5 μg/ml neocarzinostatin (NCS) was added to the medium in the last 24 hours of incubation. Fixed cells were subsequently labeled with anti-γ-H2AX antibody and with a FITC-conjugated secondary antibody. Nuclei were visualized by DAPI staining. B. Quantification of γ-H2AX-positive cells was performed by using ImageJ software and expressed as percentage of the total number of cells in each sample. Bars indicate mean values +/- standard deviation (SD) from three independent experiments. *P < 0.0001 indicates statistically significant difference in the number of γ-H2AX-positive cells in CK2-depleted versus si-Scr-treated cells. C. Cells were transfected with CK2α-, -α'-siRNA or scramble siRNA for 72 hours. 0.5 μg/ml NCS was added in the last hour of incubation. Control, refers to cell treated with transfection reagent only. Cells were allowed to form clusters for 14 days. Colonies were visualized by staining with crystal violet as described in Experimental Procedures. Bar graph shows cell colonies quantification. Average values +/- SD from three independent experiments are shown relative to control (i.e. transfection reagent-treated) cells. *P < 0.005 denotes statistically significant difference in number of colonies formed as compared to si-Scr-tranfected and NCS treated cells.