Fig. 4

Bleomycin impacts DNA repair by transcriptionally downregulating the expression of Rad51. A, B A549 cells were treated with bleomycin at the indicated concentrations and time, the expression of Rad51 was determined by Western blotting. C A549 cells treated with vehicle or 10 μM bleomycin for 24 h were analyzed by immunofluorescence using anti-Rad51 antibodies. D A549 cells were exposed to the indicated doses of bleomycin for 24 h, and Rad51 mRNA was assessed by RT-PCR. E A549 cells were treated with 10 μM bleomycin 24 h before transfection with the luciferase reporter. Relative luciferase activity was determined by normalizing firefly luciferase against renilla luciferase activity. F The expression levels of E2F1 after 24 h of bleomycin exposure were analyzed by Western blotting. Significance markers: *p < 0.05; **p < 0.01 compared to control; n = 3