Project description:Analysis of acute myeloid leukemia KG1 cells treated with XX-650-23 (5 mM) for 12hrs. XX-650-23 inhibits proliferation of KG1 cells. Results provides insight into the molecular mechanisms underlying by the inhibitory activity of XX-650-23 on acute leukemia. mRNA profiles of KG1 cells treated with XX-650-23 were generated by deep sequencing. CREB genome binding profiles of KG1 cells treated with XX-650-23 were generated by deep sequencing.
Project description:Analysis of acute myeloid leukemia KG1 cells treated with XX-650-23 (5 mM) for 12hrs. XX-650-23 inhibits proliferation of KG1 cells. Results provides insight into the molecular mechanisms underlying by the inhibitory activity of XX-650-23 on acute leukemia.
Project description:Dysregulated gene expression is one of the most prevalent features in human cancers. Here, we show that most subtypes of acute myeloid leukemia (AML) depend on the aberrant assembly of the MYB transcriptional co-activator complex. By rapid and selective peptidomimetic interference with the binding of CBP/P300 to MYB, but not CREB or MLL1, we find that the leukemic functions of MYB are mediated by CBP/P300-mediated co-activation of a distinct set of transcriptional factor complexes that are aberrantly assembled with MYB in AML cells. This therapeutic remodeling is accompanied by dynamic redistribution of CBP/P300 complexes to genes that control cellular differentiation and growth. Thus, aberrantly organized transcription factor complexes control convergent gene expression programs in AML cells. These findings establish a compelling strategy for pharmacologic reprogramming of oncogenic gene expression that supports its targeting for leukemias and other human cancers caused by dysregulated gene control.
Project description:Aberrant gene expression is a hallmark of acute leukemias. However, therapeutic strategies for its blockade are generally lacking, in large part due to the pharmacologic challenges of drugging transcription factors. MYB-driven gene trans-activation with CREB-binding protein (CBP) is required for the initiation and maintenance of a variety of acute lymphoblastic and myeloid leukemias, including refractory MLL-rearranged leukemias. Using structure-guided molecular design, we developed a prototypical peptidomimetic inhibitor MYBMIM that interferes with the assembly of the molecular MYB:CBP complex at ¼M concentrations and rapidly accumulates in the nuclei of AML cells. We found that treatment of AML cells with MYBMIM, but not with its inactive near-isosteric analogue TG3, led to the displacement and dissociation of MYB:CBP complex in cells, displacement of MYB from oncogenic enhancers and promoters enriched for MYB binding sites, and rapid downregulation of MYB-dependent gene expression, including of MYC and BCL2 oncogenes. Both human MLL-rearranged and non-rearranged AML cells, but not normal CD34+ umbilical cord blood progenitor cells, underwent sustained mitochondrial apoptosis in response to MYBMIM treatment, an effect that could be partially rescued by ectopic expression of BCL2. We observed that MYBMIM treatment impeded leukemia growth and extended survival of immunodeficient mice engrafted with primary patient-derived MLL-rearranged leukemia cells. These findings emphasize the exquisite dependence of human AML on MYB:CBP transcriptional dysregulation, and establish a pharmacologic approach for its therapeutic blockade.
Project description:Aberrant gene expression is a hallmark of acute leukemias. However, therapeutic strategies for its blockade are generally lacking, in large part due to the pharmacologic challenges of drugging transcription factors. MYB-driven gene trans-activation with CREB-binding protein (CBP) is required for the initiation and maintenance of a variety of acute lymphoblastic and myeloid leukemias, including refractory MLL-rearranged leukemias. Using structure-guided molecular design, we developed a prototypical peptidomimetic inhibitor MYBMIM that interferes with the assembly of the molecular MYB:CBP complex at ¼M concentrations and rapidly accumulates in the nuclei of AML cells. We found that treatment of AML cells with MYBMIM, but not with its inactive near-isosteric analogue TG3, led to the displacement and dissociation of MYB:CBP complex in cells, displacement of MYB from oncogenic enhancers and promoters enriched for MYB binding sites, and rapid downregulation of MYB-dependent gene expression, including of MYC and BCL2 oncogenes. Both human MLL-rearranged and non-rearranged AML cells, but not normal CD34+ umbilical cord blood progenitor cells, underwent sustained mitochondrial apoptosis in response to MYBMIM treatment, an effect that could be partially rescued by ectopic expression of BCL2. We observed that MYBMIM treatment impeded leukemia growth and extended survival of immunodeficient mice engrafted with primary patient-derived MLL-rearranged leukemia cells. These findings emphasize the exquisite dependence of human AML on MYB:CBP transcriptional dysregulation, and establish a pharmacologic approach for its therapeutic blockade.
Project description:Aberrant gene expression is a hallmark of acute leukemias. However, therapeutic strategies for its blockade are generally lacking, in large part due to the pharmacologic challenges of drugging transcription factors. MYB-driven gene trans-activation with CREB-binding protein (CBP) is required for the initiation and maintenance of a variety of acute lymphoblastic and myeloid leukemias, including refractory MLL-rearranged leukemias. Using structure-guided molecular design, we developed a prototypical peptidomimetic inhibitor MYBMIM that interferes with the assembly of the molecular MYB:CBP complex at ¼M concentrations and rapidly accumulates in the nuclei of AML cells. We found that treatment of AML cells with MYBMIM, but not with its inactive near-isosteric analogue TG3, led to the displacement and dissociation of MYB:CBP complex in cells, displacement of MYB from oncogenic enhancers and promoters enriched for MYB binding sites, and rapid downregulation of MYB-dependent gene expression, including of MYC and BCL2 oncogenes. Both human MLL-rearranged and non-rearranged AML cells, but not normal CD34+ umbilical cord blood progenitor cells, underwent sustained mitochondrial apoptosis in response to MYBMIM treatment, an effect that could be partially rescued by ectopic expression of BCL2. We observed that MYBMIM treatment impeded leukemia growth and extended survival of immunodeficient mice engrafted with primary patient-derived MLL-rearranged leukemia cells. These findings emphasize the exquisite dependence of human AML on MYB:CBP transcriptional dysregulation, and establish a pharmacologic approach for its therapeutic blockade.
Project description:The MYB oncogene is widely expressed in acute leukemias and is important for the continued proliferation of leukemia cells, raising the possibility that MYB may be a therapeutic target. However realization of this potential requires (i) a significant therapeutic window for MYB inhibition, given its essential role in normal hematopoiesis; and (ii) an approach for developing an effective therapeutic. We previously showed that the interaction of Myb with the coactivator CBP/p300 is essential for its transforming activity. Here we use hematopoietic cells from the Booreana mouse strain, which carries a mutation in Myb that prevents interaction with CBP/p300, to examine the requirement for this interaction in myeloid transformation and leukemogenesis. Using this strain and a strain (plt6) carrying a “complementary” mutation in p300, we show that the Myb-p300 interaction is essential for in vitro transformation by the myeloid leukemia oncogenes AML1-ETO, AML1-ETO9a, MLL-ENL, and MLL-AF9. We further show that unlike cells from wild-type (WT) mice, Booreana cells fail to induce leukemia upon transplantation into irradiated recipients following transduction with an AML1-ETO9a retrovirus. These data highlight disruption of the Myb-p300 interaction as a potential therapeutic strategy for AML and suggest that such a strategy would have a useable therapeutic index since Booreana mice, unlike Myb null mice, are viable. Finally we have begun to explore the molecular basis of the these observations by gene expression profiling; this highlighted several genes previously implicated in myeloid leukemogenesis as being differentially expressed between WT and Booreana cells transduced with AML1-ETO9a. Total RNA was obtained from FACS sorted GFP+;c-Kit+ primary bone marrow cells from WT and Booreana mouse strains which had been cultured for 48 hours post-transduction with Control or AML1-ETO9a retroviruses. RNA was extracted from each of 4 samples per group and used to probe Illumina mouse Beadchips array.
Project description:The bromodomain and extraterminal (BET) protein Brd4 is a validated drug target in leukemia, yet its regulatory function in this disease is not well understood. Here, we show that Brd4 chromatin occupancy in acute myeloid leukemia closely correlates with the hematopoietic transcription factors (TFs) Pu.1, Fli1, Erg, C/EBPα, C/EBPβ, and Myb at nucleosome-depleted enhancer and promoter regions. We provide evidence that these TFs, in conjunction with the lysine acetyltransferase activity of p300/CBP, facilitate Brd4 recruitment to their occupied sites to promote transcriptional activation. Moreover, chemical inhibition of BET bromodomains is found to suppress the functional output each hematopoietic TF, thereby interfering with essential lineage-specific transcriptional circuits in this disease. These findings reveal a chromatin-based signaling cascade comprised of hematopoietic TFs, p300/CBP, and Brd4, which supports leukemia maintenance and is suppressed by BET bromodomain inhibition. PolyA selected RNA-Seq for drug treated or shRNA-expressing MLL-AF9 transformed acute myeloid leukemia cells (RN2)
Project description:The bromodomain and extraterminal (BET) protein Brd4 is a validated drug target in leukemia, yet its regulatory function in this disease is not well understood. Here, we show that Brd4 chromatin occupancy in acute myeloid leukemia closely correlates with the hematopoietic transcription factors (TFs) Pu.1, Fli1, Erg, C/EBPα, C/EBPβ, and Myb at nucleosome-depleted enhancer and promoter regions. We provide evidence that these TFs, in conjunction with the lysine acetyltransferase activity of p300/CBP, facilitate Brd4 recruitment to their occupied sites to promote transcriptional activation. Moreover, chemical inhibition of BET bromodomains is found to suppress the functional output each hematopoietic TF, thereby interfering with essential lineage-specific transcriptional circuits in this disease. These findings reveal a chromatin-based signaling cascade comprised of hematopoietic TFs, p300/CBP, and Brd4, which supports leukemia maintenance and is suppressed by BET bromodomain inhibition. ChIP-Seq for regulatory factors of Brd4 in MLL-AF9 transformed acute myeloid leukemia cells (RN2)