title: Identification of p21WAF1/CIP1 as a direct target of EWS-Fli1 oncogenic fusion protein.
abstract: Translocation t(11;22) is a karyotypic abnormality detected in over 90% of Ewing's family tumors. This translocation results in the EWS-Fli1 fusion gene, which has been shown to be a potent, single-step transforming gene. We reported previously that suppression of the EWS-Fli1 fusion protein altered the expression of G(1) regulatory cyclins and cyclin-dependent kinase inhibitors both at mRNA and protein levels, resulting in G(1) growth arrest in Ewing's family tumor cell lines. These data suggest that the G(1) regulatory molecules may be targets of the EWS-Fli1 fusion protein, which functions as an aberrant transcription factor. By using electrophoretic mobility shift assays, we show here the direct association of EWS-Fli1 fusion protein with ETS consensus sequences, which are in the promoter of the p21(WAF1/CIP1) gene. Reporter gene assays revealed that the activity of the p21(WAF1/CIP1) promoter is negatively regulated by EWS-Fli1 fusion protein through at least two ETS-binding sites in the promoter. EWS-Fli1 interacted with p300 cotransactivator and suppressed its histone acetyltransferase activity, which may explain the down-regulation of p21(WAF1/CIP1) by EWS-Fli1. In the presence of a histone deacetylase inhibitor, the histone acetyltransferase activity of the Ewing's family tumor cell was recovered resulting in the induction of p21, and the cell growth was dramatically inhibited. These results demonstrated that p21(WAF1/CIP1) might be one of the direct targets of EWS-Fli1, and that p21(WAF1/CIP1) could serve as a target for a molecularly based therapy for Ewing's family tumors.
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Nakatani
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Tanaka
authors.forename: Riku
authors.initials: R
authors.lastname: Sakimura
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Tomoya
authors.initials: T
authors.lastname: Matsunobu
authors.forename: Xu
authors.initials: X
authors.lastname: Li
authors.forename: Masuo
authors.initials: M
authors.lastname: Hanada
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Okada
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D000123:Acetyltransferases / Q000037:antagonists & inhibitors; D000818:Animals; D001665:Binding Sites; D002087:Butyrates / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors; D002460:Cell Line; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000037:antagonists & inhibitors / Q000235:genetics*; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D051548:Histone Acetyltransferases; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D020319:Oligodeoxyribonucleotides, Antisense / Q000008:administration & dosage / Q000494:pharmacology; D015514:Oncogene Proteins, Fusion / Q000378:metabolism / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D012512:Sarcoma, Ewing / Q000188:drug therapy / Q000473:pathology; D014157:Transcription Factors / Q000378:metabolism / Q000494:pharmacology*; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor
chemical_list: D000123:Acetyltransferases; D002087:Butyrates; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D051548:Histone Acetyltransferases; D020319:Oligodeoxyribonucleotides, Antisense; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D014157:Transcription Factors; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; C106031:EWS-FLI fusion protein