title: Cucurbitacin B induces DNA damage, G2/M phase arrest, and apoptosis mediated by reactive oxygen species (ROS) in leukemia K562 cells.
abstract: Cucurbitacin B (Cuc B) is a natural product with potent anti-cancer activities in solid tumors. We investigated the anti-cancer effect of Cuc B on K562 leukemia cells. Cuc B drastically decreased cell viability in a concentration-dependent manner. Cuc B treatment caused DNA damage, as shown by long tails in the comet assay and increased γH2AX protein expression. Immunofluorescence, Fluo3- AM, and JC-1 staining results showed that Cuc B treatment induced nuclear γH2AX foci, increased intracellular calcium ion concentration, and depolarized mitochondrial membrane potential (MMP), respectively. Cuc B induced G2/M phase arrest and apoptosis, as shown by flow cytometry, DNA fragmentation, and protein expression analyses. In addition, Cuc B dramatically increased intracellular reactive oxygen species (ROS) generation as measured by DCFH2-DA. N-acetyl-l-cysteine pretreatment significantly reversed Cuc B-induced DNA damage, increased intracellular calcium ion concentration, and reduced MMP, G2/M phase arrest, and apoptosis. Taken together, these results suggested that ROS mediated Cuc B-induced DNA damage, G2/M arrest, and apoptosis in K562 cells. This study provides novel mechanisms to better understand the underlying anti-cancer mechanisms of Cuc B.
authors.forename: Jiajie
authors.initials: J
authors.lastname: Guo
authors.forename: Wenwen
authors.initials: W
authors.lastname: Zhao
authors.forename: Wenhui
authors.initials: W
authors.lastname: Hao
authors.forename: Guowen
authors.initials: G
authors.lastname: Ren
authors.forename: Jinjian
authors.initials: J
authors.lastname: Lu
authors.affiliation: Institute of Chinese Medical Sciences, University of Macau, Av. Padre Tomas Pereira S.J., Taipa, Macau, China. xpchen@umac.mo.
authors.forename: Xiuping
authors.initials: X
authors.lastname: Chen
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects*; D016166:Free Radical Scavengers / Q000494:pharmacology; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects*; D006657:Histones / Q000378:metabolism; D006801:Humans; D020014:K562 Cells; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014315:Triterpenes / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D016166:Free Radical Scavengers; C468783:H2AX protein, human; D006657:Histones; D017382:Reactive Oxygen Species; D014315:Triterpenes; C041246:cucurbitacin B; D002118:Calcium; D000111:Acetylcysteine