Skip to main content
Figure 3 | BMC Chemical Biology

Figure 3

From: Catalytic inhibition of topoisomerase II by a novel rationally designed ATP-competitive purine analogue

Figure 3

Assessment of catalytic topoisomerase II inhibitor relative cellular potency. (A) Catalytic inhibition of topoisomerase II by ICRF-193 prevents induction of DNA damage by doxorubicin in HL-60 cells as assessed by γH2AX Western blotting. Histone H3 levels are shown as loading control. Both drugs were incubated at 5 μM. Cells were pretreated with ICRF-193 for 30 minutes prior to addition of doxorubicin for 2 hours. (B) Induction of γH2AX by doxorubicin (5 μM, 2 hours treatment) is abolished in HeLa cells in which topoisomerase II alpha and beta have been depleted by siRNA. Histone H3 levels are shown as loading control in the Western blots. (C) Representative examples of the γH2AX in-cell western assay in 96 well format showing suppression of doxorubicin-induced γH2AX signal by increasing concentrations of ICRF-193 and QAP 1, respectively. Control designates non-specific γH2AX signal detected in wells where primary antibody was omitted to correct for background. TO-PRO was used to normalize for cell numbers. (D) IC50 determination of the inhibition of doxorubicin-induced γH2AX signal by QAP 1 and ICRF-193, respectively.

Back to article page