Fig. 4

ATM inhibition reduces the intracellular labile iron pool. a Erastin treatment increases intracellular labile iron pool (LIP). MDA-MB-231 cells were treated with indicated concentrations of erastin for 6 h, and incubated with Calcien-AM. The relative LIP was calculated based on the differences in the fluorescence intensity before and after DFO chelation. (The data was acquired from six biological replicates performed in parallel; Student’s t-test; *p < 0.05, **p < 0.01) b ATM inhibition by Ku-55933 decreases intracellular labile iron pool. MDA-MB-231 cells were treated with Ku-55933 (5 μM) for 24 h, and incubated with Calcien-AM to measure the relative LIP. (The data was acquired from eight biological replicates performed in parallel; Student’s t-test; **p < 0.01) c Depletion of ATM by siRNA decreases intracellular labile iron pool. MDA-MB-231 cells were transfected with indicated siRNA for 72 h, and incubated with Calcien-AM to measure the relative LIP. (The data was acquired from four biological replicates performed in parallel; Student’s t-test; *p < 0.05) d Iron supplementation sensitizes ATM-depleted cells against erastin. MDA-MB-231 cells were transfected with siNC or siATM for 72 h, and then incubated with DMSO, erastin (10 μM), with or without ferric citrate (50 μM) for indicated time point. The amount of cell death was evaluated by CellTox-Green at each time point. The data presented are mean ± S.D. from four biological replicates, and the data were reproduced from two independent experiments. P-values were calculated by Student’s t-test, **p < 0.01