title: Overcoming resistance to conventional drugs in Ewing sarcoma and identification of molecular predictors of outcome.
abstract: OBJECTIVE
  The improvement of Ewing sarcoma (EWS) therapy is currently linked to the discovery of strategies to select patients with poor and good prognosis and of modified treatment regimens. In this study, we analyzed the molecular factors governing EWS response to chemotherapy to identify genetic signatures to be used for risk-adapted therapy.
  
  
  METHODS
  Microarray technology was used for profiling 30 primary tumors and seven metastases of patients who were classified according to event-free survival. For selected genes, real-time polymerase chain reaction was applied in 42 EWS primary tumors as validation assay. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test was used to evaluate in vitro drug sensitivity.
  
  
  RESULTS
  We identified molecular signatures that reflect tumor resistance to chemotherapy. Annotation analysis was applied to reveal the biologic functions that critically influenced clinical outcome. The prognostic relevance of glutathione metabolism pathway was validated. The expression of MGST1, the microsomal glutathione S-transferase (GST), was found to clearly predict EWS prognosis. MGST1 expression was associated with doxorubicin chemosensitivity. This prompted us to assess the in vitro effectiveness of 6-(7-nitro-2,1,3-benzoxadiazol-4-ylthio)hexanol (NBDHEX), a new anticancer agent that efficiently inhibits GST enzymes. Six cell lines were found to be sensitive to this new drug.
  
  
  CONCLUSIONS
  Classification of EWS patients into high- and low-risk groups is feasible with restricted molecular signatures that may have practical value at diagnosis for selecting patients with EWS who are unresponsive to current treatments. Glutathione metabolism pathway emerged as one of the most significantly altered prognosis-associated pathway. NBDHEX is proposed as a new potential therapeutic possibility.
authors.affiliation: Laboratory of Oncologic Research, Orthopaedic Institute Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy. katia.scotlandi@ior.it
authors.forename: Katia
authors.initials: K
authors.lastname: Scotlandi
authors.forename: Daniel
authors.initials: D
authors.lastname: Remondini
authors.forename: Gastone
authors.initials: G
authors.lastname: Castellani
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Manara
authors.forename: Filippo
authors.initials: F
authors.lastname: Nardi
authors.forename: Lara
authors.initials: L
authors.lastname: Cantiani
authors.forename: Mirko
authors.initials: M
authors.lastname: Francesconi
authors.forename: Mario
authors.initials: M
authors.lastname: Mercuri
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Caccuri
authors.forename: Massimo
authors.initials: M
authors.lastname: Serra
authors.forename: Sakari
authors.initials: S
authors.lastname: Knuutila
authors.forename: Piero
authors.initials: P
authors.lastname: Picci
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000235:genetics; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D005260:Female; D020869:Gene Expression Profiling; D051549:Glutathione S-Transferase pi / Q000235:genetics; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D008297:Male; D010069:Oxadiazoles / Q000627:therapeutic use*; D025341:Principal Component Analysis; D011379:Prognosis; D012512:Sarcoma, Ewing / Q000188:drug therapy* / Q000235:genetics
chemical_list: C528479:6-(7-nitro-2,1,3-benzoxadiazol-4-ylthio)hexanol; D000970:Antineoplastic Agents; D010069:Oxadiazoles; C122107:microsomal glutathione S-transferase-I; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase