title: Small interfering RNAs expressed from a Pol III promoter suppress the EWS/Fli-1 transcript in an Ewing sarcoma cell line.
abstract: The EWS/Fli-1 fusion gene encodes an oncogenic fusion protein. The fusion is a product of the translocation t(11;22) (q24;q12), which is detected in 85% of Ewing sarcoma and primitive neuroectodermal tumor cells. Utilizing intracellularly expressed 21- to 23-nucleotide small interfering RNAs (siRNAs) targeting the EWS/Fli-1 fusion transcript in an Ewing sarcoma cell line, we achieved a greater than 80% reduction in the EWS/Fli-1 transcript. The reduction in transcript levels was accompanied by growth inhibition of an Ewing cell line. In addition to quantitating the reduction of the fusion transcript, we carefully monitored reduction of the endogenous EWS and Fli-1 mRNAs as well. One of the two siRNAs targeted to the fusion transcript also partially downregulated the Fli-1 mRNA, further potentiating the growth inhibition. These results highlight both the power of siRNAs and the potential side reactions that need to be carefully monitored. In addition, these results provide the first demonstration of expressed siRNAs downregulating an oncogenic fusion transcript. The results and observations from these studies should prove useful in targeting other fusion transcripts characteristic of sarcomas and erythroleukemias.
authors.affiliation: Division of Molecular Biology, Beckman Research Institute of the City of Hope, 1450 East Duarte Road, Duarte, California 91010, USA.
authors.forename: Taikoh
authors.initials: T
authors.lastname: Dohjima
authors.forename: Nan Sook
authors.initials: NS
authors.lastname: Lee
authors.forename: Haitang
authors.initials: H
authors.lastname: Li
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Ohno
authors.forename: John J
authors.initials: JJ
authors.lastname: Rossi
mesh_terms: D001859:Bone Neoplasms / Q000235:genetics / Q000628:therapy*; D004258:DNA Polymerase III / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation; D006801:Humans; D015514:Oncogene Proteins, Fusion / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D051789:Proto-Oncogene Protein c-fli-1; D034741:RNA, Small Interfering / Q000627:therapeutic use*; D034802:RNA-Binding Protein EWS; D012512:Sarcoma, Ewing / Q000235:genetics / Q000628:therapy*; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: C106031:EWS-FLI fusion protein; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034741:RNA, Small Interfering; D034802:RNA-Binding Protein EWS; D014157:Transcription Factors; D004258:DNA Polymerase III