CCAAT/enhancer binding protein alpha (C/EBPalpha) and C/EBPalpha myeloid oncoproteins induce bcl-2 via interaction of their basic regions with nuclear factor-kappaB p50.
Mol Cancer Res
; 3(10): 585-96, 2005 Oct.
Article
em En
| MEDLINE
| ID: mdl-16254192
ABSTRACT
The CEBPA gene is mutated in 10% of acute myeloid leukemia (AML) cases. We find that CEBPA and Bcl-2 RNA levels correlate highly in low-risk human AMLs, suggesting that inhibition of apoptosis via induction of bcl-2 by CCAAT/enhancer binding protein alpha (C/EBPalpha) or its mutant variants contributes to transformation. C/EBPalphap30, lacking a NH2-terminal transactivation domain, or C/EBPalphaLZ, carrying in-frame mutations in the leucine zipper that prevent DNA binding, induced bcl-2 in hematopoietic cell lines, and C/EBPalpha induced bcl-2 in normal murine myeloid progenitors and in the splenocytes of H2K-C/EBPalpha-Emu transgenic mice. C/EBPalpha protected Ba/F3 cells from apoptosis on interleukin-3 withdrawal but not if bcl-2 was knocked down. Remarkably, C/EBPalphaLZ oncoproteins activated the bcl-2 P2 promoter despite lack of DNA binding, and C/EBPalphap30 also activated the promoter. C/EBPalpha and the C/EBPalpha oncoproteins cooperated with nuclear factor-kappaB (NF-kappaB) p50, but not p65, to induce bcl-2 transcription. Endogenous C/EBPalpha preferentially coimmunoprecipitated with p50 versus p65 in myeloid cell extracts. Mutation of residues 297 to 302 in the C/EBPalpha basic region prevented induction of endogenous bcl-2 or the bcl-2 promoter and interaction with p50 but not p65. These findings suggest that C/EBPalpha or its mutant variants tether to a subset of NF-kappaB target genes, including Bcl-2, via p50 to facilitate gene activation and offer an explanation for preferential in-frame rather than out-of-frame mutation of the leucine zipper with sparing of the basic region in C/EBPalphaLZ oncoproteins. Targeting interaction between C/EBPalpha basic region and NF-kappaB p50 may contribute to the therapy of AML and other malignancies expressing C/EBPs.
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Coleções:
01-internacional
Temas:
Geral
/
Tipos_de_cancer
/
Outros_tipos
Base de dados:
MEDLINE
Assunto principal:
Leucemia Mieloide Aguda
/
Proteínas Oncogênicas
/
Proteínas Proto-Oncogênicas c-bcl-2
/
Proteína alfa Estimuladora de Ligação a CCAAT
/
Subunidade p50 de NF-kappa B
Limite:
Adult
/
Animals
/
Humans
Idioma:
En
Revista:
Mol Cancer Res
Assunto da revista:
BIOLOGIA MOLECULAR
/
NEOPLASIAS
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
Estados Unidos