Combined transcriptional and translational targeting of EWS/FLI-1 in Ewing's sarcoma.
OBJECTIVE
To show the efficacy of targeting EWS/FLI-1 expression with a combination of specific antisense oligonucleotides and rapamycin for the control of Ewing's sarcoma (EWS) cell proliferation in vitro and the treatment of mouse tumor xenografts in vivo.


METHODS
EWS cells were simultaneously exposed to EWS/FLI-1-specific antisense oligonucleotides and rapamycin for various time periods. After treatment, the following end points were monitored and evaluated: expression levels of the EWS/FLI-1 protein, cell proliferation, cell cycle distribution, apoptotic cell death, caspase activation, and tumor growth in EWS xenografts implanted in nude mice.


RESULTS
Simultaneous exposure of EWS cells in culture to an EWS/FLI-1-targeted suppression therapy using specific antisense oligonucleotides and rapamycin resulted in the activation of a caspase-dependent apoptotic process that involved the restoration of the transforming growth factor-beta-induced proapoptotic pathway. In vivo, individual administration of either antisense oligonucleotides or rapamycin significantly delayed tumor development, and the combined treatment with antisense oligonucleotides and rapamycin caused a considerably stronger inhibition of tumor growth.


CONCLUSIONS
Concurrent administration of EWS/FLI-1 antisense oligonucleotides and rapamycin efficiently induced the apoptotic death of EWS cells in culture through a process involving transforming growth factor-beta. In vivo experiments conclusively showed that the combined treatment with antisense oligonucleotides and rapamycin caused a significant inhibition of tumor growth in mice. These results provide proof of principle for further exploration of the potential of this combined therapeutic modality as a novel strategy for the treatment of tumors of the Ewing's sarcoma family.
Mateo-Lozano
Silvia
S
Laboratory of Experimental Carcinogenesis, Department of Radiation Medicine, V.T. Lombardi Comprehensive Cancer Center, Georgetown University, Washington, District of Columbia 20057-1482, USA.
Gokhale
Prafulla C
PC
Soldatenkov
Viatcheslav A
VA
Dritschilo
Anatoly
A
Tirado
Oscar M
OM
Notario
Vicente
V
D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols; D017209:Apoptosis / Q000187:drug effects; D001859:Bone Neoplasms / Q000628:therapy*; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D003131:Combined Modality Therapy / Q000379:methods; D004305:Dose-Response Relationship, Drug; D018390:Gene Targeting / Q000379:methods*; D015316:Genetic Therapy / Q000379:methods; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D016376:Oligonucleotides, Antisense / Q000627:therapeutic use*; D015514:Oncogene Proteins, Fusion / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D012512:Sarcoma, Ewing / Q000628:therapy*; D020123:Sirolimus / Q000627:therapeutic use; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology / Q000627:therapeutic use; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
D000903:Antibiotics, Antineoplastic; C106031:EWS-FLI fusion protein; D016376:Oligonucleotides, Antisense; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D014157:Transcription Factors; D053773:Transforming Growth Factor beta1; D053148:Caspase 3; D053179:Caspase 7; D020123:Sirolimus