Fig. 4

Knock down of 53BP1 reduces the hypersensitivity of PARP inhibitor in ATM inhibited cells a, Western blot shown that 53BP1 was efficiently knocked down by 53BP1 shRNA pool in CAL-51 cells and MCF-7 cells. b, c, MTS assays revealed the cell viability after treatment with indicated compounds for 48 h in CAL-51-sh53BP1 cells and their control counterparts (b) or in MCF-7-sh53BP1 cells and control-transfected cells (c). Left, cells were treated with 0, 5, 10 μM Olaparib. Right, cells were treated with 0, 5, 10 μM Olaparib combined with 10 μM KU55933. Cell viability was normalized to the 0 μM Olaparib (DMSO) treatment group. d, e, Colony formation assays showed the cell colony formation capacity after treatment with indicated compounds in CAL-51-sh53BP1 cells and their control counterparts (d) or in MCF-7-sh53BP1 cells and control-transfected cells (e). Cells were treated with 0, 5, 10 μM Olaparib with or without 10 μM KU55933 for 10 days. Up, representative pictures; bottom, quantitative data. All experiments were performed at least three times and data were statistically analyzed by two-tail t-test.*p < 0.05, **p < 0.01, ***p < 0.001. Error bars indicate S.E.M