20-O-IngenolEZ, a catalytic topoisomerase II inhibitor, specifically inhibits cell proliferation and induces double-strand DNA breaks in BLM-/- cells

Hypersensitive Inhibition of the Proliferation of Cells with Mutated DNA Repair-Related Genes by the Catalytic Topoisomerase II Inhibitor 20-O-IngenolEZ

“…Many studies have suggested that the decatenation checkpoint is distinct from the DNA damage checkpoint. Although, phosphorylation of H2AX was not induced when MMT cells were treated with 50 μM ICRF-193 or 200 μM 20-O-ingenolEZ for 24 h, at a concentration that completely inhibited cell proliferation, it was induced when MMT cells were treated with 0.9 μM adriamycin [16,31]. However, we have demonstrated that 20-O-in-genolEZ is a novel topo II catalytic inhibitor that induces DNA damage signaling in BLM −/− DT40 cells.…”

“…We previously reported that 20-O-ingenolEZ functions as a catalytic inhibitor and inhibits the ATPase activity of topo IIα and induces G2 arrest of MMT cells [15]. However, treatment of BLM −/− DT40 cells with 20-O-in-genolEZ induces DNA damage signaling and apoptosis [16]. Although the inhibition of cell proliferation through the induction of topo II decatenation checkpoint is weak than that by topo II damage checkpoint [17][18][19], catalytic inhibitors have low DNA truncation toxicity [20,21] and an inefficient decatenation checkpoint for stem and progenitor cells [22].…”

3EZ,20Ac-ingenol, a catalytic inhibitor of topoisomerases, downregulates p-Akt and induces DSBs and apoptosis of DT40 cells

“…After 24 and 48 h of treatment, these values were 30 and 27 %, respectively, as compared with 12 % in untreated cells. MMT cells treated with 20- O -ingenolEZ were arrested in G2/M phase, but were not induced in apoptosis, whereas DT40 cells treated with the inhibiter were induced to undergo apoptosis (Yoshida et al 2010; Watanabe et al 2011). In this study, DT40 cells treated with the dual catalytic inhibitor of topo I and II 3EZ,20Ac-ingenol were also selectively arrested in G2/M phase and were induced to undergo apoptosis through signaling by cell cycle checkpoints in G2/M phase.…”

“…1) was dissolved in dimethyl sulfoxide. BLM −/− and WRN −/− DT40 cells and DT40 cells were incubated in RPMI 1640 supplemented for 24 h at 37 °C as described previously (Watanabe et al 2011). Cell growth was determined by the 3-(4,5-dimethylthiazol-2-yl)-2-5-diphenyl-tetrazolium bromide (MTT) assay using the Cell Proliferation Kit I (Roche Applied Science).…”

“…Although, the topo I poison drugs CPT and topotecan and the topo II poison drugs adriamycin and etoposide stabilize the covalent topo–DNA cleavable complexes, thereby inducing DSBs, the topo I catalytic inhibitorβ-lapachone, the topo II catalytic inhibitor ICRF-193 and a dual catalytic inhibitor of topo I and II F 11782 do not induce DSBs (Burden and Osheroff 1998; Andoh and Ishida 1998; Capranico et al 2010). However, we reported that although 20- O -ingenolEZ inhibits the ATPase activity of topo II and induces G2 arrest by inhibiting DNA decatenation in mouse mammary tumor (MMT) cells, it induces DSBs and apoptosis in BLM −/− DT40 cells (Watanabe et al 2011). Recent studies have suggested that catalytic topo II inhibitor ICRF-193 induces DSBs by acting as topo II poisons (Park and Avraham 2006; Robinson et al 2007).…”