Project description:Cytogenetically normal acute myeloid leukemia (CN-AML) represents nearly 50% of human acute myeloid leukemia (AML) cases with a 5-year overall survival of approximately 30%. In CN-AML with poorer prognosis, mutations in the de novo DNA methyltransferase (DNMT3A) and the FMS-like tyrosine kinase 3 (Flt3) commonly co-occur (1-3). We demonstrate that mice with Flt3-internal-tandem duplication (Flt3ITD) and inducible deletion of Dnmt3a spontaneously develop a rapidly-lethal, completely-penetrant, and transplantable AML of normal karyotype. These murine AML retain a single Dnmt3a floxed allele, revealing the oncogenic potential of Dnmt3a haploinsufficiency. FLT3-ITD/DNMT3A-mutant primary human and murine AML demonstrate a similar pattern of global DNA methylation. In the murine model, rescuing DNMT3A expression was accompanied by DNA re-methylation and loss of clonogenic potential, suggesting that Dnmt3a-mutant oncogenic effects are reversible. Differentially methylated genomic regions were associated with changes in the expression of nearby genes. Moreover, dissection of the cellular architecture of the AML model using single-cell RNA-Seq, flow cytometry and colony assays identified clonogenic subpopulations that differentially express genes that are sensitive to the methylation of nearby genomic loci and varied in response to Dnmt3a levels. Thus, Dnmt3a haploinsufficiency transforms Flt3ITD myeloproliferative disease by modulating methylation-sensitive gene expression within a clonogenic AML subpopulation. To identify the gene expression changes associated with Dnmt3a loss of function in human and murine Flt3-ITD and Dnmt3a-mutant AML (Bulk RNA-Seq).
Project description:Cytogenetically normal acute myeloid leukemia (CN-AML) represents nearly 50% of human acute myeloid leukemia (AML) cases with a 5-year overall survival of approximately 30%. In CN-AML with poorer prognosis, mutations in the de novo DNA methyltransferase (DNMT3A) and the FMS-like tyrosine kinase 3 (Flt3) commonly co-occur (1-3). We demonstrate that mice with Flt3-internal-tandem duplication (Flt3ITD) and inducible deletion of Dnmt3a spontaneously develop a rapidly-lethal, completely-penetrant, and transplantable AML of normal karyotype. These murine AML retain a single Dnmt3a floxed allele, revealing the oncogenic potential of Dnmt3a haploinsufficiency. FLT3-ITD/DNMT3A-mutant primary human and murine AML demonstrate a similar pattern of global DNA methylation. In the murine model, rescuing DNMT3A expression was accompanied by DNA re-methylation and loss of clonogenic potential, suggesting that Dnmt3a-mutant oncogenic effects are reversible. Differentially methylated genomic regions were associated with changes in the expression of nearby genes. Moreover, dissection of the cellular architecture of the AML model using single-cell RNA-Seq, flow cytometry and colony assays identified clonogenic subpopulations that differentially express genes that are sensitive to the methylation of nearby genomic loci and varied in response to Dnmt3a levels. Thus, Dnmt3a haploinsufficiency transforms Flt3ITD myeloproliferative disease by modulating methylation-sensitive gene expression within a clonogenic AML subpopulation. To identify the gene expression changes associated with Dnmt3a loss of function in human and murine Flt3-ITD and Dnmt3a-mutant AML (Single Cell RNA-Seq).
Project description:Effectively targeting leukemia-initiating cells (LIC) in FLT3-internal-tandem-duplication (ITD)-mutated acute myeloid leukemia (AML) remains a crucial goal for achievement of cure. FLT3 tyrosine kinase inhibitors (TKI) have limited impact as single agents and have thus far been unable to eradicate LIC enriched in the CD34+CD38- bone marrow compartment and protected by contact with niche cells.Using primary AML samples in vitro as well as in an in vivo xenograft model, we investigated whether combining the novel FLT3-selective TKI crenolanib with the hypomethylating agent azacitidine (AZA) can eliminate LIC in FLT3-ITD+ AML and determined whether efficacy of this combination is dependent on coexisting genetic mutations in DNMT3A, NPM1 and TET2. Our data show that crenolanib as a single agent was unable to target FLT3-ITD+ LIC in contact with niche cells while the addition of AZA overcame stromal protection and resulted in dramatically reduced clonogenic capacity of FLT3-ITD+ LIC in vitro as well as severely impaired engraftment capacity of FLT3-ITD+ LIC in NSG mice. Strikingly, FLT3-mutated AML samples harboring concurrent TET2 mutations were completely resistant to crenolanib as a single agent. Mutations in DNMT3A or NPM1 had no influence on response to crenolanib while DNMT3A mutations conferred increased sensitivity of FLT3-ITD+ LIC to AZA. Our data suggest that response to crenolanib or AZA as single agents in FLT3-ITD+ AML is highly dependent on coexisting mutations in epigenetic regulators. However, the combination of AZA + crenolanib effectively eliminated FLT3-ITD+ LIC irrespective of additional mutations in NPM1, DNMT3A or TET2.
Project description:The presence of FLT3-ITD mutations in patients with acute myeloid leukemia (AML) is associated with poor clinical outcome. FLT3 tyrosine kinase inhibitors (TKIs), although effective in kinase ablation, do not eliminate FLT3-ITD+ leukemia stem cells (LSCs) which are potential sources of disease relapse, prompting us to ask whether FLT3-ITD protein regulates the AML LSCs survival through a kinase-independent mechanism. Here, we show that expression of PRMT1, the primary type I arginine methyltransferase, significantly increases in LSC-enriched CD34+CD38- populations relative to normal counterparts. Genetic PRMT1 depletion blocked AML CD34+ cell survival, and had more potent effects in AML cells from patients harboring FLT3-ITD. Our genome wide analysis of gene expression and PRMT1 conditional KO mouse study confirmed that PRMT1 preferentially cooperates with FLT3-ITD contributing to AML cell maintenance. Mechanistically, PRMT1 catalyzed FLT3-ITD protein methylation at arginines 972/973, and PRMT1 promoted leukemia cell growth in a FLT3 methylation-dependent manner. Moreover, effects of FLT3-ITD methylation in AML cells were in part due to crosstalk with FLT3-ITD phosphorylation at tyrosine 969 (Y969). Importantly, FLT3 methylation persisted in FLT3-ITD+ AML cells following TKI (AC220) treatment, indicating that methylation occurs independently of kinase activity. Finally, in both patient-derived xenograft (PDX) and murine AML models, combined administration of AC220 with a type I PRMT inhibitor (MS023) enhanced elimination of FLT3-ITD+ AML relative to AC220 treatment alone. Our study demonstrates that PRMT1-mediated FLT3 methylation promotes LSC activity and suggests that combining PRMT1 inhibition with FLT3 TKI treatment could be a promising approach to selectively target FLT3-ITD+ LSCs.
Project description:Cytogenetically normal acute myeloid leukemia (CN-AML) represents nearly 50% of human acute myeloid leukemia (AML) cases with a 5-year overall survival of approximately 30%. In CN-AML with poorer prognosis, mutations in the de novo DNA methyltransferase (DNMT3A) and the FMS-like tyrosine kinase 3 (Flt3) commonly co-occur (1-3). We demonstrate that mice with Flt3-internal-tandem duplication (Flt3ITD) and inducible deletion of Dnmt3a spontaneously develop a rapidly-lethal, completely-penetrant, and transplantable AML of normal karyotype. These murine AML retain a single Dnmt3a floxed allele, revealing the oncogenic potential of Dnmt3a haploinsufficiency. FLT3-ITD/DNMT3A-mutant primary human and murine AML demonstrate a similar pattern of global DNA methylation. In the murine model, rescuing DNMT3A expression was accompanied by DNA re-methylation and loss of clonogenic potential, suggesting that Dnmt3a-mutant oncogenic effects are reversible. Differentially methylated genomic regions were associated with changes in the expression of nearby genes. Moreover, dissection of the cellular architecture of the AML model using single-cell RNA-Seq, flow cytometry and colony assays identified clonogenic subpopulations that differentially express genes that are sensitive to the methylation of nearby genomic loci and varied in response to Dnmt3a levels. Thus, Dnmt3a haploinsufficiency transforms Flt3ITD myeloproliferative disease by modulating methylation-sensitive gene expression within a clonogenic AML subpopulation.
Project description:We want to obtain FLT3-ITD gene signature. To do so, we transduced CB CD34+ cells with mock or FLT3-ITD vectors and performed RNA sequencing (RNA-Seq). Two Groups: Group1: CB CD34+ cells transduced with mock vector; Group2: CB CD34+ cells transduced with FLT3-ITD vector;
Project description:Internal tandem duplication (ITD) mutations within the FMS-like receptor tyrosine kinase-3 (FLT3) can be found in up to 25~30% of acute myeloid leukemia (AML) patients and confer a poor prognosis. Although FLT3 tyrosine kinase inhibitors (TKIs) have shown clinical responses, the overall outcome of FLT3-ITD+ AML patients remains poor, and most of them would relapse very shortly. TKIs can not eliminate primitive FLT3-ITD+ AML cells, which are potential sources of relapse. Therefore, elucidating the mechanisms underlying FLT3-ITD+ AML maintenance and drug resistance is essential to develop novel, effective treatment strategies. Here, we demonstrate that FLT3 inhibition induces histone deacetylase 8 (HDAC8) upregulation through FOXO1 and FOXO3-mediated transactivation in FLT3-ITD+ AML cells. Upregulated HDAC8 deacetylates and inactivates p53, leading to leukemia maintenance and drug resistance upon TKIs treatment. Genetic or pharmacological inhibition of HDAC8 re-activates p53, abrogates leukemia maintenance and significantly enhances TKI-mediated elimination of FLT3-ITD+ AML cells. Importantly, in FLT3-ITD+ AML patient-derived xenograft models, the combination of FLT3 TKI (AC220) with a HDAC8 inhibitor (22d) significantly inhibits leukemia progression and effectively reduces primitive FLT3-ITD+ AML cells. Moreover, we extend these findings to an AML subtype harboring another tyrosine kinase activating mutation. In conclusion, our study demonstrates that HDAC8 upregulation as an important mechanism to resist TKIs and promote leukemia maintenance, and suggests that combining HDAC8 inhibition with TKI treatment could be a promising strategy to treat FLT3-ITD+ AML and other tyrosine kinase mutation-harboring leukemias.
Project description:We assessed global gene expression profiles in two mouse models of oncogenic FLT3-driven leukemia in the presence and absence of Dnmt3a.