title: G226, a new epipolythiodioxopiperazine derivative, triggers DNA damage and apoptosis in human cancer cells in vitro via ROS generation.
abstract: OBJECTIVE
  G226 is a novel derivative of epipolythiodioxopiperazines with potent inhibitory activity against cancer cells. Here, we sought to identify potential targets involved in the anti-cancer activity of G226.
  
  
  METHODS
  Cell proliferation assay was conducted in a panel of 12 human cancer cell lines. The activities of topoisomerase I (Topo I) and Topo II were studied using supercoiled pBR322 DNA relaxation and kDNA decatenation assays. ROS production was assessed with probes DCFH-DA and H&E. Western blot analysis and flow cytometry were used to examine DNA damage, apoptosis and cell cycle changes.
  
  
  RESULTS
  G226 displayed potent cytotoxicity in the 12 human cancer cell lines with a mean IC50 value of 92.7 nmol/L. This compound (1-100 μmol/L) selectively inhibited the activity of Topo II, and elevated the expression of phosphorylated-H2AX in a dose-dependent manner. In Topo II-deficient HL60/MX2 cells, however, G226-induced DNA damage, apoptosis and cytotoxicity were only partially reduced, suggesting that Topo II was not essential for the anti-tumor effects of G226. Furthermore, G226 (0.125-2 μmol/L) dose-dependently elevated the intracellular levels of H2O2 and in the cancer cells, and pretreatment with GSH, NAC or DTT not only blocked G226-induced intracellular accumulation of ROS, but also abrogated G226-mediated phosphorylation of H2AX, apoptosis and cytotoxicity.
  
  
  CONCLUSIONS
  G226-mediated ROS production contributes to the anti-cancer activity of this compound.
authors.affiliation: Institute of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Peng-xing
authors.initials: PX
authors.lastname: He
authors.affiliation: Division of Anti-tumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Beijing Institute of Pharmacology & Toxicology, Beijing 100190, China.
authors.forename: Yong-sheng
authors.initials: YS
authors.lastname: Che
authors.affiliation: Institute of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Qiao-jun
authors.initials: QJ
authors.lastname: He
authors.affiliation: Division of Anti-tumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Division of Anti-tumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Ding
mesh_terms: D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004249:DNA Damage; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D054659:Diketopiperazines / Q000494:pharmacology*; D004220:Disulfides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D045325:HCT116 Cells; D018922:HL-60 Cells; D019073:HT29 Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D020128:Inhibitory Concentration 50; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D018384:Oxidative Stress / Q000187:drug effects*; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D059005:Topoisomerase II Inhibitors / Q000494:pharmacology*
chemical_list: D000951:Antigens, Neoplasm; D000975:Antioxidants; D004268:DNA-Binding Proteins; D054659:Diketopiperazines; D004220:Disulfides; C000600490:G226 compound; C468783:H2AX protein, human; D006657:Histones; D010879:Piperazines; D017382:Reactive Oxygen Species; D059005:Topoisomerase II Inhibitors; D004250:DNA Topoisomerases, Type II