title: [Inducing effect of cyclosporin A on apoptosis of multidrug resistant cell lines HR20 and HT9].
abstract: OBJECTIVE
  Multidrug resistant (MDR) cells can resist drug-induced apoptosis, which is the functional mechanism for many chemotherapeutic drugs. It is necessary to search for the molecular mechanism underlying anti-apoptosis of MDR cells. However, because of the anti-apoptosis characteristic of MDR cells, it is hard to study the mechanism on their apoptosis pathway. This study was to induce apoptosis in human acute leukemia cell line HL-60, and its MDR cell lines HR20 and HT9 by cyclosporin A (CsA), analyze the differences in apoptosis pathway between MDR cells and sensitive cells by detecting several important apoptosis-related molecules.
  
  
  METHODS
  HL-60, HR20, and HT9 cells were treated with 10, and 20 mg/L of CsA, cell apoptosis was identified by cell morphologic changes,electrophoresis,and flow cytometry. Changes of apoptosis-related factors were detected by spectrophotometer and Western blot.
  
  
  RESULTS
  HL-60, HR20, and HT9 cells all showed obvious apoptotic characteristics after treated with CsA,such as chromatin condensation, DNA fragmentation factor (DFF) degradation and activation, and DNA fragmentation. However, Caspase-3 activation was only detected in apoptotic HL-60 cells.
  
  
  CONCLUSIONS
  CsA may induce apoptosis of HR20, and HT9 cells in a Caspase-3 independent manner, which is different from apoptosis of sensitive cells. In the apoptosis pathway of HR20, and HT9 cells, there may be some factors other than Caspase-3 that can activate DFF. It is postulated that the difficulty of Caspase-3 to be activated may be an important reason for HR20 and HT9 cells to resist apoptosis induced by many chemotherapeutic drugs.
authors.affiliation: Gynecological Oncology Center, People's Hospital, Peking University, Beijing 100044, P.R. China. chyan7581@sina.com
authors.forename: Hong-Yan
authors.initials: HY
authors.lastname: Cheng
authors.forename: Su-Wen
authors.initials: SW
authors.lastname: Li
authors.forename: Hong-Qing
authors.initials: HQ
authors.lastname: Zhang
authors.forename: Shao-Bai
authors.initials: SB
authors.lastname: Xue
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D002467:Cell Nucleus / Q000473:pathology; D016572:Cyclosporine / Q000494:pharmacology*; D003630:Daunorubicin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D018922:HL-60 Cells; D006801:Humans; D011506:Proteins / Q000378:metabolism; D014750:Vincristine / Q000494:pharmacology
chemical_list: D051017:Apoptosis Regulatory Proteins; D011506:Proteins; C109664:caspase-activated DNase inhibitor; D014750:Vincristine; D004317:Doxorubicin; D016572:Cyclosporine; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D003630:Daunorubicin