title: 3EZ,20Ac-ingenol, a catalytic inhibitor of topoisomerases, downregulates p-Akt and induces DSBs and apoptosis of DT40 cells.
abstract: We have previously reported that many ingenol compounds derived from Euphorbia kansui exhibit topoisomerase (topo) II inhibitory activity. Of these compounds, 3EZ,20Ac-ingenol inhibited topo I activity. Camptothecin, which inhibits the religation activity of topo I without interfering with the binding of topo I to DNA and induces topo I-mediated DNA cleavage, was used as a positive control. In this study, we found that 3EZ,20Ac-ingenol did not hamper the binding of topo I to DNA in the same manner as camptothecin but affected the inhibition of cleavage of one DNA strand. 3EZ,20Ac-ingenol inhibited cell proliferation by blocking cell cycle progression in the G2/M phase. To define the mechanism of inhibition of DT40 cell proliferation, the change in Akt activity was observed because Akt activity is regulated in response to DNA damage. Western blot analysis revealed that 3EZ,20Ac-ingenol downregulated the expression of p-Akt, and apoptosis was detected by the presence of DNA double-strand breaks and caspase 3 activation.
authors.affiliation: Department of Chemistry, College of Humanities and Sciences, Nihon University, Tokyo 156-8550, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Fukuda
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kanbe
authors.forename: Manami
authors.initials: M
authors.lastname: Watanabe
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Dan
authors.forename: Keiichi
authors.initials: K
authors.lastname: Matsuzaki
authors.forename: Susumu
authors.initials: S
authors.lastname: Kitanaka
authors.forename: Shohei
authors.initials: S
authors.lastname: Miyata
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002384:Catalysis; D049109:Cell Proliferation / Q000187:drug effects; D002645:Chickens; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects*; D004224:Diterpenes / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects* / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000378:metabolism; D059003:Topoisomerase Inhibitors / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D004224:Diterpenes; D059003:Topoisomerase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; C008125:ingenol