Figure 4.

Clonogenic survival of either non-irradiated or irradiated MDA-MB-231 cells after siRNA transfection. A. Clonogenic survival of MDA-MB-231 cells after transfection. Treatment with just OpnS had a strong effect on clonogenic survival at 0 Gy. The relative clonogenic survival of cells that were transfected with nonsense siRNA was arbitrarily established as 100%. Data represent the average values (± SD) of three independent experiments (* p < 0.05, ** p < 0.001). B. Clonogenic survival after transfection with OPN-specific siRNA (Mix, OpnS) in combination with irradiation at 2, 4 or 6 Gy. To examine the additional effects of irradiation all values of clonogenic survival at 0 Gy were set arbitrarily at 100%. Cells transfected with OpnS showed an increased radiosensitivity. After irradiation at 6 Gy, a dose modifying factor (DMF₁₀) of 1.1 and an enhancement factor of 1.5 (p = 0.09) were calculated for the siRNA construct OpnS. Data represent the average values (± SD) of three independent experiments.