Activated notch counteracts Ikaros tumor suppression in mouse and human T cell acute lymphoblastic leukemia
Journal Title
Leukemia
Publication Type
Journal Article
Abstract
Activating NOTCH1 mutations occur in approximately 60% of human T lineage acute lymphoblastic leukemias (T-ALLs), and mutations disrupting the transcription factor IKZF1 (IKAROS) occur in 5% of cases. To investigate the regulatory interplay between these driver genes we have used a novel transgenic RNAi mouse model to produce primary T-ALLs driven by reversible Ikaros knockdown. Restoring endogenous Ikaros expression in established T-ALL in vivo acutely represses Notch1 and its oncogenic target genes including Myc, and in multiple primary leukemias causes disease regression. In contrast, leukemias expressing high levels of endogenous or engineered forms of activated intracellular Notch1 (ICN1) resembling those found in human T-ALL rapidly relapse following Ikaros restoration, indicating that ICN1 functionally antagonizes Ikaros in established disease. Furthermore, we find that IKAROS mRNA expression is significantly reduced in a cohort of primary human T-ALL patient samples with activating NOTCH1FBXW7 mutations, but is upregulated upon acute inhibition of aberrant NOTCH signaling across a panel of human T-ALL cell lines. These results demonstrate for the first time that aberrant NOTCH activity compromises IKAROS function in mouse and human T-ALL, and provide a potential explanation for the relative infrequency of IKAROS gene mutations in human T-ALL.Leukemia accepted article preview online, 06 February 2015. doi:10.1038/leu.2015.27.
Publisher
NPG
WEHI Research Division(s)
Molecular Medicine; Molecular Immunology; Bioinformatics
NHMRC Grants
NHMRC/575535 NHMRC/1024599 NHMRC/490037
Rights Notice
Refer to copyright notice on published article.


Creation Date: 2015-03-06 11:42:21
Last Modified: 2015-06-15 09:00:37
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