The role of the core-binding factor ß (CBFß) subunit in the CBF heterodimeric complex.

Abstract Among acute myeloid leukemia (AML) with cytogenetic abnormalities, core binding factor (CBF) leukemia acounts for 20-30% of adult AML, and 20-30% of pediatric AML. The chromosome 16 inversion (inv(16)), which results in a fusion gene CBFB -MYH11 and an encoded chimeric protein CBFβ-SMMHC (core binding factor β - smooth muscle myosin heavy chain), is observed primarily in AML subtype M4Eo. Using Cbfb-MYH11 knock-in mouse models we previously demonstrated that CBFβ-SMMHC needs its C terminal domains for leukemogenesis (Kamikubo et al, Blood 121:638, 2013). In this study we generated a new CBFB-MYH11 knock-in mouse model to determine the role of the multimerization domain at the C terminus of CBFβ-SMMHC for hematopoietic defects and leukemogenesis. Previous studies have shown that the C-terminal 29-residue assembly competent domain (ACD) is essential for multimerization of SMMHC. Within ACD, clustered point mutations in helices D and E specifically disrupts multimerization of CBFβ-SMMHC without interfering with the repression function of CBFβ-SMMHC (Zhang et al., Oncogene 25:7289, 2006). Therefore, we generated knock-in mice expressing CBFβ-SMMHC with mutated helices D and E (mDE) to study the role of the multimerization domain in vivo. Heterozygous embryos (Cbfb+/mDE) were viable and showed no defects in fetal liver definitive hematopoiesis, while homozygous embryos (CbfbmDE/mDE) showed complete blockage of definitive hematopoiesis, hemorrhage in the central nervous system and midgestation lethality, similar to the phenotype in Cbfb+/MYH11 mice and the Cbfb or Runx1 null mice. This phenotype is also similar to that in the homozygous knockin embryos expressing C-terminally-deleted CBFβ-SMMHC (Kamikubo et al, Blood 121:638, 2013). The fetal liver of E12.5 CbfbmDE/mDE embryos gave no colonies while the fetal liver of Cbfb+/mDE mice generated similar number of colonies as the WT controls. We further looked at the peripheral blood of E10.5 CbfbmDE/mDE embryos and found that the primitive hematopoiesis was not affected, while E10.5 Cbfb+/MYH11 embryos showed a developmental delay at this stage. Analysis of peripheral blood showed decreased B cell population in young adult Cbfb+/mDE mice, while the myeloid compartment was unchanged. In aged mice (>12 months), however, there was an increase of immature myeloid cells in the peripheral blood. Importantly, there was no leukemia development in the Cbfb+/mDE mice one year after ENU treatment (to induce cooperating mutations), while Cbfb+/MYH11 micedied of leukemia within 2 months of ENU treatment. Notably bone marrow cells in the Cbfb+/mDE and Cbfb+/MYH11 mice expressed their respective fusion proteins at similar levels. Overall our data suggest that the C terminal multimerization domain is required for the defects in primitive and definitive hematopoiesis caused by CBFβ-SMMHC, and the domain is essential for leukemogenesis by CBFβ-SMMHC. Further mechanistic studies of this domain may lead to new drug targets for treating inv(16) leukemia. For this purpose we have performed gene expression profiling with microarray and RNA-seq technologies, comparing gene expression changes in adult bone marrow c-Kit+ cells as well as embryonic primitive blood cells from Cbfb+/mDE and Cbfb+/MYH11 mice. Preliminary analysis indicates that the gene expression profile of the hematopoietic cells from the Cbfb+/mDE mice was much similar to that of Cbfb+/+ than Cbfb+/MYH11 mice. Validation and pathway analysis of those differentially expressed genes are ongoing and the results will be presented at the annual meeting. Disclosures No relevant conflicts of interest to declare.

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The core-binding factor β subunit is required for bone formation and hematopoietic maturation

Nature Genetics ◽

10.1038/ng1049 ◽

2002 ◽

Vol 32 (4) ◽

pp. 645-649 ◽

Cited By ~ 118

Author(s):

Janelle Miller ◽

Alan Horner ◽

Terryl Stacy ◽

Christopher Lowrey ◽

Jane B. Lian ◽

...

Keyword(s):

Bone Formation ◽

Β Subunit ◽

Core Binding Factor ◽

The Core ◽

Binding Factor

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Analysis of the core binding factor beta (Cbfb)-dependent transcriptome in embryonic mouse peripheral blood

Signaling Pathways Project Datasets ◽

10.1621/m1ap1ntnyg ◽

2019 ◽

Author(s):

RK Hyde

Keyword(s):

Peripheral Blood ◽

Core Binding Factor ◽

Embryonic Mouse ◽

The Core ◽

Binding Factor ◽

Core Binding Factor Beta

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An update on the molecular pathogenesis and potential therapeutic targeting of AML with t(8;21)(q22;q22.1);RUNX1-RUNX1T1

Blood Advances ◽

10.1182/bloodadvances.2019000168 ◽

2020 ◽

Vol 4 (1) ◽

pp. 229-238 ◽

Cited By ~ 3

Author(s):

Sayer Al-Harbi ◽

Mahmoud Aljurf ◽

Mohamad Mohty ◽

Fahad Almohareb ◽

Syed Osman Ali Ahmed

Keyword(s):

Histone Deacetylases ◽

Kinase Inhibitors ◽

Normal Function ◽

Leukemic Cells ◽

Proliferative Potential ◽

Core Binding Factor ◽

The Core ◽

Expression Of Genes ◽

Binding Factor ◽

Epigenetic Modulation

Abstract Acute myeloid leukemia (AML) with t(8;21)(q22;q22.1);RUNX1-RUNX1T1, one of the core-binding factor leukemias, is one of the most common subtypes of AML with recurrent genetic abnormalities and is associated with a favorable outcome. The translocation leads to the formation of a pathological RUNX1-RUNX1T1 fusion that leads to the disruption of the normal function of the core-binding factor, namely, its role in hematopoietic differentiation and maturation. The consequences of this alteration include the recruitment of repressors of transcription, thus blocking the expression of genes involved in hematopoiesis, and impaired apoptosis. A number of concurrent and cooperating mutations clearly play a role in modulating the proliferative potential of cells, including mutations in KIT, FLT3, and possibly JAK2. RUNX1-RUNX1T1 also appears to interact with microRNAs during leukemogenesis. Epigenetic factors also play a role, especially with the recruitment of histone deacetylases. A better understanding of the concurrent mutations, activated pathways, and epigenetic modulation of the cellular processes paves the way for exploring a number of approaches to achieve cure. Potential approaches include the development of small molecules targeting the RUNX1-RUNX1T1 protein, the use of tyrosine kinase inhibitors such as dasatinib and FLT3 inhibitors to target mutations that lead to a proliferative advantage of the leukemic cells, and experimentation with epigenetic therapies. In this review, we unravel some of the recently described molecular pathways and explore potential therapeutic strategies.

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The Role of C-KIT Mutations in the Leukemogenesis of Core-Binding Factor Acute Myeloid Leukemia: A Comparative Analysis on Paired Diagnosis and Relapse Samples.

Blood ◽

10.1182/blood.v108.11.2307.2307 ◽

2006 ◽

Vol 108 (11) ◽

pp. 2307-2307

Author(s):

Der-Cherng Liang ◽

Lee-Yung Shih ◽

Chein-Fuang Huang ◽

Ya-Tzu Chang ◽

Huei-Ying Li ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Comparative Analysis ◽

Crucial Role ◽

Myeloid Leukemia ◽

Tandem Repeats ◽

Core Binding Factor ◽

Kit Mutation ◽

Binding Factor ◽

Acute Myeloid

Abstract C-KIT is a member of the type III receptor tyrosine kinase family and plays a crucial role in normal hematopoiesis and acute myeloid leukemia (AML). C-KIT mutations have been described in core-binding factor (CBF) AML at initial diagnosis. The role of C-KIT mutations in the relapse of CBF AML is not clear. In the present study, we analyzed C-KIT mutations on paired diagnosis and relapse samples in CBF AML. Among 1014 adults and 162 children with AML, CBF AML was detected in 11.4% of adults and 25.3% of children. Mutational analysis of C-KIT was performed by direct sequencing for all cDNA PCR products amplified with 5 overlapping primer pairs, which cover the whole coding sequences of C-KIT gene from exon 1 through exon 21. In AML with t(8;21)/AML1-ETO, 33.0 % (29/88) of adults and 44.4 % (12/27) of children had C-KIT mutations. In AML with inv(16)/CBFβ-MYH11, 22.2 % (6/27) of adults and 38.5 %(5/13) of children had C-KIT mutations. Taken together, C-KIT mutations were present in 30.4 % (35/115) of adults and 42.5 % (17/40) of children with CBF AML. Forty-two patients with CBF AML relapsed. Twenty-two(18 adults and 4 children) of the 23 patients with CBF AML and C-KIT(+) at diagnosis had relapse samples available for comparative analysis. All the 22 patients relapsed with C-KIT mutations, 21 of them showed the identical C-KIT mutation patterns as those at diagnosis. Of the 20 relapsed patients with t(8;21)/AML1-ETO and C-KIT(+), 3 had mutations in exon 8: T417_D419delinsY, Y418_D419delinsA, and [Y418N;Y418_D419insFF], respectively; one had mutation in exon 9: I478V; another one had mutation in exon 11: [D572_P573insL; E561_D572dup]; 14 had mutations in exon 17: 5 D816V, 3 N822K, 3 D816Y, and one each with D816H, D820G, and D820Y; the remaining one patient relapsed twice, the patterns of C-KIT mutations changed but remained in exon 17: D816A at diagnosis, D816V at the first relapse, and N822K at the second relapse. Genotyping analysis with 15 loci of short tandem repeats at 13 different chromosomes showed identity for the diagnosis and the two relapse samples. Of the 2 adults with inv(16)/CBFβ-MYH11 and C-KIT(+) who relapsed, both had mutations in exon 17: N822K and D816Y, respectively. C-KIT mutations were absent in all of the 35 complete remission samples examined. In those with CBF AML and C-KIT(−) at diagnosis, 19 patients including 16 adults and 3 children relapsed; C-KIT mutations were not present in all the relapse samples except one who acquired D816H mutation. The present study showed that all patients with de novo CBF AML harboring C-KIT mutations at diagnosis retained the mutations at relapse, indicating that C-KIT mutations play a crucial role in the leukemogenesis in a substantial proportion of patients with CBF AML.

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