Overcoming resistance to conventional drugs in Ewing sarcoma and identification of molecular predictors of outcome.
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.
Scotlandi
Katia
K
Laboratory of Oncologic Research, Orthopaedic Institute Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy. katia.scotlandi@ior.it
Remondini
Daniel
D
Castellani
Gastone
G
Manara
Maria Cristina
MC
Nardi
Filippo
F
Cantiani
Lara
L
Francesconi
Mirko
M
Mercuri
Mario
M
Caccuri
Anna Maria
AM
Serra
Massimo
M
Knuutila
Sakari
S
Picci
Piero
P
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
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