Downregulation and forced expression of EWS-Fli1 fusion gene results in changes in the expression of G(1)regulatory genes.
Chromosomal translocation t(11;22)(q24:q12) is detected in approximately 90% of tumours of the Ewing family (ET). This translocation results in EWS-Fli1 gene fusion which produces a EWS-Fli1 fusion protein acting as an aberrant transcriptional activator. We previously reported that the inhibition of EWS-Fli1 expression caused the G(0)/G(1)arrest of ET cells. We, therefore, hypothesized that EWS-Fli1 may affect the expression of G(1)regulatory genes. Downregulation of EWS-Fli1 fusion proteins was observed 48 hours after the treatment with EWS-Fli1 antisense oligonucleotides. The expressions of G(1)cyclins, cyclin D1 and cyclin E, were markedly decreased in parallel with the reduction of EWS-Fli1 fusion protein. On the other hand, the expression of p21 and p27, which are important cyclin-dependent kinase inhibitors (CKIs) for G(1)--S transition, was dramatically increased after the treatment with EWS-Fli1 antisense oligonucleotides. RT-PCR analysis showed that alteration of the expressions of the cyclins and CKIs occurred at the mRNA level. Furthermore, transfection of EWS-Fli1 cDNA to NIH3T3 caused transformation of the cells and induction of the expression of cyclin D1 and E. Clinical samples of ET also showed a high level of expression of cyclin D1 mRNA, whereas mRNAs for p21 and p27 were not detected in the samples. These findings strongly suggest that the G(1)--S regulatory genes may be involved in downstream of EWS-Fli1 transcription factor, and that the unbalanced expression of G(1)--S regulatory factors caused by EWS-Fli1 may lead to the tumorigenesis of ET.
Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Y
Y
Matsumoto
K
K
Tanaka
F
F
Nakatani
T
T
Matsunobu
S
S
Matsuda
Y
Y
Iwamoto
D016475:3T3 Cells; D000818:Animals; D019938:Cyclin D1 / Q000235:genetics; D019927:Cyclin E / Q000235:genetics; D018076:DNA, Complementary; D004268:DNA-Binding Proteins / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D051379:Mice; D016376:Oligonucleotides, Antisense; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012512:Sarcoma, Ewing / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics; D014407:Tumor Cells, Cultured
D019927:Cyclin E; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C497426:Fli1 protein, mouse; D016376:Oligonucleotides, Antisense; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D019938:Cyclin D1