The t(8;21) fusion protein, AML1/ETO, transforms NIH3T3 cells and activates AP-1

Frank, Richard C.; Sun, Xiao Jian; Berguido, Francisco J.; Jakubowiak, Andrzej; Nimer, Stephen D.

doi:10.1038/sj.onc.1202459

Cited by 51 publications

(47 citation statements)

References 58 publications

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“…NIH3T3 cells have been utilized to demonstrate the transforming potential of several leukemia-specific fusion proteins (Kamps et al, 1991;Hajra et al, 1995;Frank et al, 1999). In our study, we first tested the transforming potential of MLL-EEN fusion protein in Figure 1c).…”

Section: Characterization Of Oncogenic Features Of Mll-een Fusion Genementioning

confidence: 99%

Functional contribution of EEN to leukemogenic transformation by MLL-EEN fusion protein

et al. 2004

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The EEN (extra eleven nineteen) gene was originally cloned from a case of acute myeloid leukemia M5 subtype with translocation t (11; 19)(q23; p13), in which EEN was fused with MLL. To explore the involvement of EEN in leukemogenesis caused by MLL-EEN, we studied the transformation potential of the MLL-EEN fusion protein.MLL-EEN had oncogenic features, while, as a control, MLLD, the truncated form of MLL lacking the EEN moiety, did not show any oncogenic potential. MLL-EEN exerted a dominant-negative effect over wild-type EEN in terms of subcellular localization. Normally, EEN was found in the cytoplasm, but the MLL-EEN fusion protein was located in the nucleus, and EEN could be delocalized by MLL-EEN. This interaction is via a coiled-coil dimerization domain of EEN, which is reserved in the fusion protein. In addition, MLL-EEN might act as a potential transcriptional factor with the MLL part providing the DNA-binding domain and the EEN part providing the transcription activation domain, though EEN seems to have no direct role in transcriptional regulation. As an aberrant transcriptional factor, MLL-EEN could transactivate the promoter of HoxA7, a potential target gene of MLL.

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Section: Characterization Of Oncogenic Features Of Mll-een Fusion Genementioning

confidence: 99%

Functional contribution of EEN to leukemogenic transformation by MLL-EEN fusion protein

et al. 2004

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“…Although attempts had been made to identify the critical domains required for AE-mediated transformation, conflicting results were presented from most of these studies using well-established cell lines, which suffer from the pitfalls of carrying multiple irrelevant genetic mutations that may not reflect the normal biology of the disease [for a summary see Hug et al (5)]. For example, NHR4 was required to inhibit differentiation of U937 cells (15) but was dispensable for transformation of NIH 3T3 cells (16). The only available structure/function data on primary cells are limited to NHR2 of the ETO portion of the fusion but cannot distinguish the functional contribution between homo-oligomerization and hetero-oligomerization (13).…”

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confidence: 99%

“…In acute myeloid leukemia in which leukemic stem cells have been functionally identified, AML1 and CBF␤ represent the most commonly mutated targets (1,2). t (8;21) resulting in AML1-ETO (AE) fusion can be found in up to 40% of AML-M2; and inv (16) leading to CBF␤-SHMMC fusion constitutes approximately 30% of AML-M4. AML1 is also fused to TEL as a result of t (12;21) in approximately 25% of childhood leukemia, the most common form of childhood cancers.…”

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confidence: 99%

Transforming activity of AML1-ETO is independent of CBFβ and ETO interaction but requires formation of homo-oligomeric complexes

Kwok

Zeisig

Qiu

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Although both heterodimeric subunits of core binding factors (AML1/RUNX1 and CBF␤) essential for normal hematopoiesis are frequently mutated to form different chimeric fusion proteins in acute leukemia, the underlying molecular mechanisms and structural domains required for cellular transformation remain largely unknown. Despite the critical role of CBF␤ for wild-type AML1 function and its direct involvement in chromosomal translocation, we demonstrate that both the expression and interaction with CBF␤ are superfluous for AML1-ETO (AE)-mediated transformation of primary hematopoietic cells. Similarly, the hetero-oligomeric interaction with transcriptional repressor ETO family proteins and the highly conserved NHR1 domain in AE fusion are also dispensable for transforming activity. In contrast, AE-mediated transformation is critically dependent on the DNA binding and homo-oligomeric properties of the fusion. Abolishment of homooligomerization by a small-molecule inhibitor could specifically suppress AML1 fusion-mediated transformation of primary hematopoietic cells. Together, these results not only identify the essential molecular components but also potential avenues for therapeutic targeting of AE-mediated leukemogenesis.A ML1/RUNX1 and CBF␤ are 2 critical transcription factors essential for generation of hematopoietic stem cells (HSCs) (1, 2). Mice deficient in AML1 or CBF␤ have almost identical phenotypes; they completely lack definitive hematopoiesis and die at approximately embryonic day 12.5. In acute myeloid leukemia in which leukemic stem cells have been functionally identified, AML1 and CBF␤ represent the most commonly mutated targets (1, 2). t(8;21) resulting in AML1-ETO (AE) fusion can be found in up to 40% of AML-M2; and inv(16) leading to CBF␤-SHMMC fusion constitutes approximately 30% of AML-M4. AML1 is also fused to TEL as a result of t(12;21) in approximately 25% of childhood leukemia, the most common form of childhood cancers. Although animal modeling clearly indicates that AML1 fusions per se are not sufficient for induction of full-blown leukemia, they function to enhance self-renewal and expand targeted HSCs and early progenitors for cooperative secondary mutations to take place (3-5).While enhanced self-renewal has emerged as a critical feature associated with various oncogenic transcription factors involved in acute leukemia (6-8), much less is known about the underlying molecular mechanisms. It is clear that most, if not all, of the transcription factors do not work as monomers but need to complex with various proteins for full activity and specificity, although the molecular composition of the associated transcriptional complexes required for self-renewal remains largely unknown. At the molecular level, AE encodes the DNA-binding runt homology domain (RHD) fused in-frame with almost the entire transcriptional repressor protein ETO containing 4 different Nervy homology regions (NHRs) (Fig. 1A), suggesting a gain of transcriptional repressor function by the oncogenic fusion (9). A well-reco...

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“…10 We have used an NIH3T3 transformation assay to analyze the function of AML1-ETO, which defined its transforming activity and its ability to up-regulate AP-1 activity (with c-jun and ATF-2 as possible downstream effectors in this signaling cascade). 24 In addition, AML1-ETO has been shown to repress promoter activation by AML1 in hematopoietic 25 and nonhematopoietic cell lines. 26 Much has been learned from these studies, including the critical role of the ETO portion of the fusion protein in recruiting corepressor molecules, the role of ETO dimerization in the function of AML1-ETO, and the identification of specific target genes that may be involved in AML1-ETOinduced effects.…”

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confidence: 99%

The AML1-ETO fusion protein promotes the expansion of human hematopoietic stem cells

Mulloy

Cammenga

MacKenzie

et al. 2002

Blood

192

203

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The acute myelogenous leukemia-1 (AML1)-ETO fusion protein is generated by the t(8;21), which is found in 40% of AMLs of the French-American-British M2 subtype. AML1-ETO interferes with the function of the AML1 (RUNX1, CBFA2) transcription factor in a dominant-negative fashion and represses transcription by binding its consensus DNA-binding site and via protein-protein interactions with other transcription factors. AML1 activity is critical for the development of definitive hematopoiesis, and haploinsufficiency of AML1 has been linked to a propensity to develop AML. Murine experiments suggest that AML1-ETO expression may not be sufficient for leukemogenesis; however, like the BCR-ABL isoforms, the cellular background in which these fusion proteins are expressed may be critical to the phenotype observed. Retroviral gene transfer was used to examine the effect of AML1-ETO on the in vitro behavior of human hematopoietic stem and progenitor cells. IntroductionThe recurrent chromosomal translocations found in acute myelogenous leukemia (AML) often involve transcription factors. Translocations may affect the level of gene expression, or more commonly, these genetic abnormalities may generate fusion or chimeric proteins with altered functional properties. Chromosomal translocations often disrupt genes that are required for the normal development of blood cells; one example is the transcription factor core-binding factor (CBF). CBF is a heterodimeric complex that binds to core enhancer elements in viral and cellular genes. Both components of CBF are affected by translocations found in human leukemias, including t(8;21), t(3;21), t(12;21), and inv(16). 1,2 The CBF␣ (AML1/RUNX1) subunit binds DNA directly, whereas the CBF␤ subunit enhances binding of CBF␣ to DNA but does not bind DNA itself. The importance of AML1 in hematopoiesis has been shown by the phenotype of AML1 and CBF␤ knockout mice. Both mice lack definitive hematopoiesis and die in utero, and embryonic stem cells from these null mice are unable to contribute to definitive hematopoiesis in chimeric mice. [3][4][5][6][7] These findings demonstrate that AML1/CBF␤ is required for the development of hematopoietic stem cells.The (8;21) translocation is associated with approximately 40% of myeloid leukemias of the French-American-British (FAB) M2 subtype and rearranges the AML1 gene on chromosome 21q22 and the ETO gene on chromosome 8q22, generating an AML1-ETO fusion protein that contains the first 177 amino acids of AML1 (including the DNA-binding domain but lacking the transcriptional activation domain of AML1) and almost the full length of the ETO protein. The role of AML1-ETO in the pathogenesis of AML has been intensely studied. Thus far, it has been shown that AML1-ETO functions mainly as a transcriptional repressor, while AML1 is mainly a transcriptional activator. 8 The importance of the ETO domain to this repression has recently been identified. ETO binds the corepressors N-CoR and mSin3 and recruits histone deacetylase activity. These functions correlate ...

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The t(8;21) fusion protein, AML1/ETO, transforms NIH3T3 cells and activates AP-1

Cited by 51 publications

References 58 publications

Functional contribution of EEN to leukemogenic transformation by MLL-EEN fusion protein

Functional contribution of EEN to leukemogenic transformation by MLL-EEN fusion protein

Transforming activity of AML1-ETO is independent of CBFβ and ETO interaction but requires formation of homo-oligomeric complexes

The AML1-ETO fusion protein promotes the expansion of human hematopoietic stem cells

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