Fig. 7.

Direct MPO inhibition reduces the level of TOP2-DNA covalent complexes formation and H2AX phosphorylation induced by etoposide or mitoxantrone in NB4 cells. (A and B) NB4 cells were pretreated with MPO inhibitors PF-1355 (10 μM, 4 hours) or MPOi-II (5 μM, 4 hours) before adding 10 or 100 μM etoposide or a vehicle control for 1 hour. (C and D) NB4 cells were pretreated with MPO inhibitors as in (A and B) before adding 0.5 or 1 μM mitoxantrone or a vehicle control for 1 hour. TOP2-DNA covalent complexes (A and C) and γH2AX (B and D) were quantified as in Figs 1 and 3. Numbers of replicates are indicated. **P < 0.01; ***P < 0.001.