title: Costunolide induces apoptosis through nuclear calcium2+ overload and DNA damage response in human prostate cancer.
abstract: OBJECTIVE
  Costunolide is a natural sesquiterpene lactone. We elucidated what to our knowledge is a novel mechanism to highlight its potential in chemotherapy for prostate cancer, particularly androgen refractory prostate cancer.
  
  
  METHODS
  Several pharmacological and biochemical assays were used to characterize the apoptotic signaling pathways of costunolide (ChromaDex™) in prostate cancer cells.
  
  
  RESULTS
  Costunolide showed effective antiproliferative activity against hormone dependent (LNCaP) and independent (PC-3 and DU-145) prostate cancer cells (ATCC®) by sulforhodamine B assay, clonogenic test and flow cytometric analysis of carboxyfluorescein succinimidyl ester labeling. In PC-3 cells data showed that costunolide induced a rapid overload of nuclear Ca(2+), DNA damage response and ATR phosphorylation. Costunolide induced G1-phase cell cycle arrest, which was supported by p21 up-regulation and its association with the cyclin dependent kinase 2/cyclin E complex. The association resulted in inhibition of the complex activity and inhibition of Rb phosphorylation. Costunolide mediated effects were substantially inhibited by glutathione, the reactive oxygen species scavenger and glutathione precursor N-acetylcysteine, and the Ca(2+) chelator BAPTA-AM other than the reactive oxygen species scavenger Trolox®. This indicated the crucial role of intracellular Ca(2+) mobilization and thiol depletion but not of reactive oxygen species production in apoptotic signaling.
  
  
  CONCLUSIONS
  Data suggest that costunolide induces the depletion of intracellular thiols and overload of nuclear Ca(2+) that cause DNA damage and p21 up-regulation. The association of p21 with the cyclin dependent kinase 2/cyclin E complex blocks cyclin dependent kinase 2 activity and inhibits Rb phosphorylation, leading to G1 arrest of the cell cycle and subsequent apoptotic cell death in human prostate cancer cells.
authors.affiliation: School of Pharmacy, National Taiwan University, Taipei, Taiwan, Republic of China.
authors.forename: Jui-Ling
authors.initials: JL
authors.lastname: Hsu
authors.forename: Shiow-Lin
authors.initials: SL
authors.lastname: Pan
authors.forename: Yunn-Fang
authors.initials: YF
authors.lastname: Ho
authors.forename: Tsong-Long
authors.initials: TL
authors.lastname: Hwang
authors.forename: Fan-Lu
authors.initials: FL
authors.lastname: Kung
authors.forename: Jih-Hwa
authors.initials: JH
authors.lastname: Guh
mesh_terms: D000704:Analysis of Variance; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D020552:Comet Assay; D004249:DNA Damage; D005434:Flow Cytometry; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012717:Sesquiterpenes / Q000494:pharmacology*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D007783:Lactones
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D002118:Calcium; D017382:Reactive Oxygen Species; D012717:Sesquiterpenes; C002602:costunolide; D007783:Lactones