title: A radiosensitizing effect of artesunate in glioblastoma cells is associated with a diminished expression of the inhibitor of apoptosis protein survivin.
abstract: OBJECTIVE
  Novel strategies to overcome an irradiation resistant phenotype may help to increase therapeutic efficacy in glioblastoma multiforme. The present study aimed to elucidate radiation sensitizing properties of artesunate, a semi synthetic derivate of artemisinin and to assess factors involved in this effect.
  
  
  METHODS
  LN229 and U87MG cells were treated with various concentrations of artesunate and radiation response was determined by a colony forming assay. Cell numbers, apoptosis induction, cell cycle distribution, and DNA repair following combined modality treatment were monitored by MTT-, caspase 3/7 assay, cytofluorometry, and γ-H2AX foci formation. Expression of survivin, survivin-GFP fusion protein, XIAP, cellular (c)IAP1 and cIAP2 was monitored by Western immunoblotting.
  
  
  RESULTS
  Treatment of glioma cells with artesunate and irradiation resulted in an increased apoptotic fraction, pronounced G2/M arrest and increased DNA damage as demonstrated by an elevated amount of γ-H2AX foci/nucleus. Incubation with artesunate lowers survivin expression in a time and dose-dependent manner, whereas expression of XIAP, cIAP1 and cIAP2 was not affected. In clonogenic assays, treatment with artesunate revealed a significantly reduced surviving fraction, whereas stable over expression of a survivin-GFP protein reversed artesunate-mediated radiosensitization.
  
  
  CONCLUSIONS
  Artesunate selectively down regulates survivin that contributes to a radio-sensitization of glioma cells by an increased induction of apoptosis, cell cycle arrest, and a hampered DNA damage response.
authors.affiliation: Department of Radiotherapy and Oncology, University of Frankfurt am Main, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Reichert
authors.forename: Vera
authors.initials: V
authors.lastname: Reinboldt
authors.forename: Stephanie
authors.initials: S
authors.lastname: Hehlgans
authors.forename: Thomas
authors.initials: T
authors.lastname: Efferth
authors.forename: Claus
authors.initials: C
authors.lastname: Rödel
authors.forename: Franz
authors.initials: F
authors.lastname: Rödel
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D037621:Artemisinins / Q000494:pharmacology*; D000077332:Artesunate; D001932:Brain Neoplasms / Q000235:genetics / Q000378:metabolism / Q000532:radiotherapy*; D002453:Cell Cycle / Q000528:radiation effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000528:radiation effects; D004260:DNA Repair / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism / Q000532:radiotherapy*; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D000077022:Survivin
chemical_list: D037621:Artemisinins; C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D009363:Neoplasm Proteins; D011838:Radiation-Sensitizing Agents; D000077022:Survivin; D000077332:Artesunate