CBFb-SMMHC inhibition triggers apoptosis by disrupting MYC chromatin dynamics in acute myeloid leukemia [ATAC-seq]
Ontology highlight
ABSTRACT: We recently reported the discovery of a small molecule inhibitor, AI-10-49 which can specially inhibit the protein-protein interaction between RUNX1 tumor suppressor and CBFβ-SMMHC oncogene. We also demonstrated that AI-10-49 can re-establish the RUNX1 transcriptional program in inv(16) cells and can extend the survival of inv(16) leukemic mice. To identify the changes in chromatin accessibility associated with AI-10-49, we performed ATAC-seq analysis in ME-1 cells [human inv(16) leukemia cell line] treated with AI-10-49.
Project description:We recently reported the discovery of a small molecule inhibitor, AI-10-49 which can specially inhibit the protein-protein interaction between RUNX1 tumor suppressor and CBFβ-SMMHC oncogene. We also demonstrated that AI-10-49 can re-establish the RUNX1 transcriptional program in inv(16) cells and can extend the survival of inv(16) leukemic mice. To identify the transcriptional changes associated with AI-10-49, we performed RNA-seq analysis in ME-1 cells [human inv(16) leukemia cell line] treated with AI-10-49.
Project description:We recently reported the discovery of a small molecule inhibitor, AI-10-49 which can specially inhibit the protein-protein interaction between RUNX1 tumor suppressor and CBFβ-SMMHC oncogene. We also demonstrated that AI-10-49 can re-establish the RUNX1 transcriptional program in inv(16) cells and can extend the survival of inv(16) leukemic mice. To identify the epigenetic changes as well as RUNX1 binding associated with AI-10-49, we performed genome wide analysis of H3K27ac histone mark as well as RUNX1 bindings in ME-1 cells [human inv(16) leukemia cell line] treated with AI-10-49.
Project description:Inversion of chromosome 16 is a consistent finding in patients with acute myeloid leukemia subtype M4 with eosinophilia (AML M4Eo), which generates a CBFB-MYH11 fusion gene. It is generally considered that CBFβ-SMMHC, the fusion protein encoded by CBFB-MYH11, is a dominant negative repressor of RUNX1. However, recent findings challenge the RUNX1-repression model for CBFβ-SMMHC mediated leukemogenesis. To definitively address the role of Runx1 in CBFB-MYH11 induced leukemia, we crossed conditional Runx1 knockout mice (Runx1f/f) with conditional Cbfb-MYH11 knockin mice (Cbfb+/56M). Upon Mx1-Cre activation in hematopoietic cells induced by poly (I:C) injection, all Mx1-CreCbfb+/56M mice developed leukemia in 5 months while no leukemia developed in Runx1f/fMx1-CreCbfb+/56M mice, and this effect was cell autonomous. Importantly, the abnormal myeloid progenitors (AMPs), a leukemia initiating cell population induced by Cbfb-MYH11 in the bone marrow, decreased and disappeared in Runx1f/fMx1-CreCbfb+/56M mice. RNA-seq analysis of AMP cells showed that genes associated with proliferation, differentiation blockage and leukemia initiation, were differentially expressed between Mx1-CreCbfb+/56M and Runx1f/fMx1-CreCbfb+/56M mice. In addition, with chromatin immunocleavage sequencing (ChIC-seq) assay, we observed a significant enrichment of RUNX1/CBFβ-SMMHC target genes in Runx1f/fMx1-CreCbfb+/56M cells, especially among down-regulated genes, suggesting that RUNX1 and CBFβ-SMMHC mainly function together as activators of gene expression through direct target gene binding. These data indicate that Runx1 is indispensable for Cbfb-MYH11 induced leukemogenesis by working together with CBFβ-SMMHC to regulate critical genes associated with the generation of a functional AMP population.
Project description:Polycomb activity is frequently altered in acute leukaemia through mutation or deletion of Polycomb Repressive Complex (PRC) components. Alterations in PRC-interacting factors such as the Core Binding Factor (CBF) complex should also affect leukemia biology, even if PRC composition is normal. We report that the acute myeloid leukemia (AML)-associated CBFβ-SMMHC fusion oncoprotein physically interacts with the PRC1 complex, and that these factors co-localize across the AML genome in a PRC2-independent manner. Depletion of CBFβ-SMMHC caused increases in genome-wide PRC1 binding and an altered association between PRC1 and RUNX1. Overall, PRC1 was more likely to be associated with active genes. CBFβ-SMMHC depletion had variable transcriptional effects, including significant reductions in expression of PRC1-bound ribosomal loci. Our results expand on the recently reported localized effect of CBFβ-SMMHC on RUNX1-mediated recruitment of PRC1 at MYC enhancer elements, providing evidence that the oncoprotein diversely affects Polycomb recruitment and transcriptional regulation across the entire AML genome.
Project description:The recurrent chromosome 16 inversion in acute myeloid leukemia generates a fusion gene between CBFB and MYH11, which in turn encodes a chimeric protein CBFβ-SMMHC (core binding factor β-smooth muscle myosin heavy chain). We previously demonstrated that CBFβ-SMMHC needs its C terminal domains for leukemogenesis. In this study, we generated a new Cbfb-MYH11 knock-in mouse model to dissect the role of the multimerization domain at the C terminus of CBFβ-SMMHC. Specifically, we mutated six amino acids in the helices D and E (mDE) of the assembly competent domain, which is important for SMMHC multimerization. We found that the embryos with the mDE mutation (Cbfb+/mDE) did not develop hematopoietic defects seen in embryos with full-length CBFβ-SMMHC (Cbfb+/MYH11). More importantly leukemia development was abolished in the adult Cbfb+/mDE mice even after mutagenesis treatment. In addition, gene expression profile of the hematopoietic cells from the Cbfb+/mDE mice was more similar to that of Cbfb+/+ mice than the Cbfb+/MYH11 mice. Our data suggest that the C terminal multimerization domain is required for the defects in primitive and definitive hematopoiesis caused by CBFβ-SMMHC, and it is also essential for leukemogenesis caused by CBFβ-SMMHC.
Project description:Dominant RUNX1 inhibition has been proposed as a common pathway for CBF-leukemia. CBFb-SMMHC, a fusion protein in human acute myeloid leukemia (AML), dominantly inhibits RUNX1 largely through its RUNX1 high-affinity binding domain (HABD). We generated knock-in mice expressing CBFb-SMMHC with a HABD deletion, CBFb-SMMHCd179-221. These mice developed leukemia highly efficiently, even though hematopoietic defects associated with Runx1-inhibition were partially rescued. To identify changes in gene expression with the deletion of the HABD, we compared the gene expression profile in leukemia samples from mice expressing CBFb-SMMHCd179-221 with those from mice expressing full length CBFb-SMMHC. Spleen cells were isolated from leukemic knock-in mice with full length CBFb-SMMHC at 2 months after ENU treatment and 2 leukemic CBFb-SMMHCd179-221 expressing chimeric mice at 3 weeks after birth. For each genotype, we performed two independent experiments with 4 Affymetrix GeneChip 430 chips.
Project description:Dominant RUNX1 inhibition has been proposed as a common pathway for CBF-leukemia. CBFb-SMMHC, a fusion protein in human acute myeloid leukemia (AML), dominantly inhibits RUNX1 largely through its RUNX1 high-affinity binding domain (HABD). We generated knock-in mice expressing CBFb-SMMHC with a HABD deletion, CBFb-SMMHCd179-221. These mice developed leukemia highly efficiently, even though hematopoietic defects associated with Runx1-inhibition were partially rescued. To identify changes in gene expression with the deletion of the HABD, we compared the gene expression profile in leukemia samples from mice expressing CBFb-SMMHCd179-221 with those from mice expressing full length CBFb-SMMHC.
Project description:We demonstrate that CBFb-SMMHCmaintains leukemia viability by inhibiting RUNX1 repression of MYC expression. Upon pharmacologic inhibition of CBF-SMMHC/RUNX1 binding, RUNX1 increases its association with three MYC distal downstream enhancers and represses MYC expression.
Project description:The CBFβ-MYH11 fusion generated by inv(16) aberration is proposed to block normal myeloid differentiation, but whether this subtype of leukemia cells is poised for an unique cell lineage remains unclear. Here, we surveyed the functional consequences of CBFβ-MYH11 in inv(16) patient blasts and two inducible systems by multi-omics profiling. The primary inv(16) cells stay closer with megakaryocyte and erythrocyte lineages along the cell differentiation trajectory, and share common transcriptomic signatures and epigenetic determiners. Using in vitro differentiation systems, we reveal that CBFβ-MYH11 knockdown establishes normal endomitosis-related processes, which are crucial for megakaryocyte maturation. Two pivotal regulators, GATA2 and KLF1, are identified to complementally occupy RUNX1 binding sites upon the fusion protein knockdown. Overexpression of GATA2 partly restores megakaryocyte directed differentiation suppressed by CBFβ-MYH11, and additional factors like KLF1 and EGR1 might be required to coordinately prevent CFB-MYH11 leukemogenesis. Together, our findings suggest that in inv(16) leukemia, the CBFβ-MYH11 fusion inhibits primed megakaryopoiesis by interfering with a balanced transcriptional program involving GATA2 and KLF1.
Project description:CHD7 interacts with CBFb-SMMHC through RUNX1 and modulates their gene expression regulation and is important for CBFB-MYH11 leukemogenesis in the mouse model.