title: Quercetin sensitizes human glioblastoma cells to temozolomide in vitro via inhibition of Hsp27.
abstract: OBJECTIVE
  Quercetin is an effective Hsp27 inhibitor and has been reported to facilitate tumor cell apoptosis. The aim of this study was to investigate whether quercetin could sensitize human glioblastoma cells to temozolomide (TMZ) in vitro.
  
  
  METHODS
  Both U251 and U87 human glioblastoma cells were treated with quercetin and/or TMZ for 48 h. Cell viability was detected using the MTT assay. Cell apoptosis was analyzed with caspase-3 activity kits and flow cytometry. Hsp27 expression and phosphorylation were examined using Western blot analysis. RNA interference using Hsp27 siRNA oligos was performed to knock down the gene expression of Hsp27.
  
  
  RESULTS
  TMZ (200 or 400 μmol/L) alone effectively inhibited the viability of U251 and U87 cells. When combined with quercetin (30 μmol/L), TMZ (100 μmol/L) significantly inhibited the cell viability, and the inhibition of TMZ (200 and 400 μmol/L) was enhanced. TMZ or quercetin anole did not affect caspase-3 activity and cell apoptosis, while TMZ combined with quercetin significantly increased caspase-3 activity and induced cell apoptosis. TMZ anole significantly increased Hsp27 phosphorylation in U251 and U87 cells, while quercetin or Hsp27 siRNA oligos combined with TMZ attenuated TMZ-induced Hsp27 phosphorylation and significantly inhibited Hsp27 expression.
  
  
  CONCLUSIONS
  Combined treatment with TMZ and quercetin efficiently suppressed human glioblastoma cell survival in vitro.
authors.affiliation: 1] Department of Neurosurgery, Second Affiliated Hospital of Soochow University, Suzhou 215004, China [2] Department of Neurosurgery, Changshu Traditional Chinese Medical Hospital, Changshu 215500, China.
authors.forename: Dong-Ping
authors.initials: DP
authors.lastname: Sang
authors.affiliation: Department of Neurosurgery, Second Affiliated Hospital of Soochow University, Suzhou 215004, China.
authors.forename: Ru-Jun
authors.initials: RJ
authors.lastname: Li
authors.affiliation: Department of Neurosurgery, Second Affiliated Hospital of Soochow University, Suzhou 215004, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Lan
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005909:Glioblastoma / Q000188:drug therapy* / Q000378:metabolism; D055551:HSP27 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D011794:Quercetin / Q000494:pharmacology*; D000077204:Temozolomide
chemical_list: D018906:Antineoplastic Agents, Alkylating; D055551:HSP27 Heat-Shock Proteins; D003606:Dacarbazine; D011794:Quercetin; D053148:Caspase 3; D000077204:Temozolomide