Myxoid liposarcoma FUS-DDIT3 fusion oncogene induces C/EBP beta-mediated interleukin 6 expression.
The myxoid/round cell liposarcoma oncogene FUS-DDIT3 is the result of a translocation derived gene fusion between the splicing factor FUS and DDIT3. In order to investigate the downstream targets of DDIT3, and the transforming effects of the FUS-DDIT3 fusion protein, we have introduced DDIT3-GFP and FUS-DDIT3-GFP constructs into a human fibrosarcoma cell line. The gene expression profiles of stable transfectants were compared to the original fibrosarcoma cell line by microarray analysis. We here report that the NFkappaB and C/EBP beta controlled gene IL6 is upregulated in DDIT3- and FUS-DDIT3-expressing fibrosarcoma cell lines and in myxoid liposarcoma cell lines. Strong expression of the tumor associated multifunctional cytokine interleukin 6 was confirmed both at mRNA and protein level. Knockdown experiments using siRNA against CEBPB transcripts showed that the effect of FUS-DDIT3 on IL6 expression is C/EBP beta dependent. Chromatin immunoprecipitation revealed direct interaction between the IL6 promoter and the C/EBP beta protein. In addition, the effect of DDIT3 and FUS-DDIT3 on the expression of other acute phase genes was examined using real-time PCR. We demonstrate for the first time that DDIT3 and FUS-DDIT3 show opposite transcriptional regulation of IL8 and suggest that FUS-DDIT3 may affect the synergistic activation of promoters regulated by C/EBP beta and NFkappaB.
Göransson
Melker
M
Lundberg Laboratory for Cancer Research (LLCR), Department of Pathology, Goteborg University, Gothenburg, Sweden. melker.goransson@llcr.med.gu.se
Elias
Erik
E
Ståhlberg
Anders
A
Olofsson
Anita
A
Andersson
Carola
C
Aman
Pierre
P
D000818:Animals; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000502:physiology*; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics*; D045744:Cell Line, Tumor; D017931:DNA Primers; D005354:Fibrosarcoma / Q000235:genetics* / Q000276:immunology; D006801:Humans; D015850:Interleukin-6 / Q000097:blood / Q000235:genetics*; D018208:Liposarcoma, Myxoid / Q000097:blood / Q000235:genetics* / Q000276:immunology; D051379:Mice; D016513:Mice, SCID; D016328:NF-kappa B / Q000378:metabolism; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000235:genetics; D034702:RNA-Binding Protein FUS / Q000235:genetics*; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000235:genetics*; D014183:Transplantation, Heterologous
D022782:CCAAT-Enhancer-Binding Protein-beta; D022762:CCAAT-Enhancer-Binding Proteins; C497249:DDIT3 protein, human; D017931:DNA Primers; C497250:Ddit3 protein, mouse; D015850:Interleukin-6; D016328:NF-kappa B; D015514:Oncogene Proteins, Fusion; D034741:RNA, Small Interfering; D034702:RNA-Binding Protein FUS; D014157:Transcription Factors; D051742:Transcription Factor CHOP