Project description:We transduced two individual murine KMT2A-MLLT3 AML samples with DOT1L and three days after sorting for DOT1L+ cells collected for RNA-seq MLL-rearranged leukemias have been previously shown to be dependent on the presence of histone 3 lysine 79 (H3K79) dimethylation on the genomic targets of the fusion, and an inhibitor of the H3K79 methyltransferase DOT1L is in clinical trials for MLL-rearranged leukemia. In order to ask what biologic effects overexpression of DOT1L would have on the H3K79me2 ChIP-Seq profiles and MLL-fusion target gene expression, murine leukemias generated by transplanting MSCV-MLL-AF9-GFP transduced lin- cKit+ Sca1+ bone marrow cells were subjected to overexpression of DOT1L. Cells were sorted into low (low level of DOT1L overexpression), high (high level of DOT1L overexpression) and bulk (entire population) samples, and subjected to H3K79me2 ChIP-Seq (using a drosophila spike in for normalization) and RNA-Seq analysis 3 days after transduction.
Project description:We transduced two individual murine KMT2A-MLLT3 AML samples with DOT1L and three days after sorting for DOT1L+ cells were collected for ChIP-Seq. Before beginning the ChIP protocol drosophila melanogaster (S2) cells were spiked in at a 1:2 ratio.
Project description:Activating signaling mutations are common in acute leukemia with KMT2A (previously MLL) rearrangements. Herein, we show that co-expression of FLT3-N676K and KMT2A-MLLT3 in human CD34+ cord blood cells primarily cause acute myeloid leukemia (AML) and rarely acute lymphoblastic leukemia (ALL) in immunodeficient mice. By contrast, expression of KMT2A-MLLT3 alone cause ALL, double-positive leukemia (DPL, expressing both CD33 and CD19), or bilineal leukemia (BLL, comprised of distinct myeloid and lymphoid leukemia cells), and rarely AML. Further, AML could only be serially propagated with maintained immunophenotype in secondary recipients when cells co-expressed KMT2A-MLLT3 and FLT3-N676K. Consistent with the idea that activated signaling would allow myeloid cells to engraft and maintain their self-renewal capacity, in a secondary recipient, a de novo KRAS-G13D was identified in myeloid cells previously expressing only KMT2A-MLLT3. Gene expression profiling revealed that KMT2A-MLLT3 DPL had a highly similar gene expression profile to ALL, with both expressing key lymphoid transcription factors and ALL cell surface markers, in line with the DPL cells being ALL cells with aberrant expression of CD33. Taken together, our results highlight the need for constitutive active signaling mutations for driving myeloid leukemia in a human xenograft model of KMT2A-R acute leukemia.
Project description:Activating mutations in kinase/PI3K/RAS signaling pathways are common in acute leukemia with KMT2A rearrangements (KMT2A-R). These mutations are often subclonal and their biological impact remain unclear. Using a retroviral acute myeloid leukemia model, we demonstrate that NRASG12D, FLT3ITD, and FLT3N676K accelerates KMT2A-MLLT3 leukemia onset. Importantly, also the presence of subclonal FLT3N676K in KMT2A-R leukemic cells shorten disease latency, possibly by providing stimulatory factors such as Mif. Acquired de novo mutations in Braf, Cbl, Kras, and Ptpn11 were identified in KMT2A-MLLT3 driven leukemia and favored clonal expansion. KMT2A-MLLT3 leukemia with an activating mutation enforce Myc- and Myb transcriptional modules, whereas KMT2A-MLLT3 leukemias lacking activating mutations displayed upregulation of signal transduction pathways. Our results provide new insight into the biology of KMT2A-R leukemia and highlights the importance of activated signaling as a contributing driver in this disease.
Project description:KMT2A-MLLT3, a fusion protein formed by the t(9;11) translocation in acute myeloid leukemia, is an epigenetic transcription factor that is known to regulate a unique leukemic gene expression profile. We show that rearranged during transfection (RET) proto-oncogene is highly overexpressed in the KMT2A-MLLT3 subgroup. In addition to biochemical studies, the RNA-seq and ATAC seq analyses have been performed in KMT2A-MLLT3 positive MOLM-13 AML cell line, compared to the umbilical cord blood-driven CD34+ hematopoietic stem progenitor cells.
Project description:KMT2A-rearranged acute lymphoblastic leukemia (ALL) is an aggressive type of leukemia which represents the most common form diagnosed in infancy. Oncogenic KMT2A-fusion proteins recruit histone methyltransferase DOT1L which leads to misplaced H3K79 methylation inducing an abnormal transcriptomic landscape that favors leukemia development. Hence, inhibition of DOT1L represents an attractive therapeutic strategy. Unfortunately, the first-in-class DOT1L inhibitor pinometostat resulted in the development of resistance. To understand this resistance we established acquired resistance to DOT1L inhibition in a pediatric KMT2A::AFF1+ B-ALL cell line model that stably became ~35-fold more resistant to pinometostat. Interestingly, while becoming almost completely independent of DOT1L-mediated H3K79 methylation, these cells remained fully dependent on the physical presence of DOT1L, HOXA9, as well as the KMT2A::AFF1 fusion protein. Further characterization of these cells using RNA-, ChIP-, and ATAC-sequencing analyses revealed that acquired resistance to DOT1L inhibition leads to a selective loss of KMT2A-fusion driven epigenetic regulation and expression of genes such as PROM1 (encoding the hematopoietic/leukemia stem cell marker CD133) and its enhancer TAPT1, as well as other putative KMT2A::AFF1 target genes such as RUNX2, PRSS12, ZC3H12, and GNAQ. In contrast, the levels of H3K79me2 and expression of other KMT2A::AFF1 target genes, including HOXA9, MEIS1, and CDK6 remained unaffected. Concomitantly, pinometostat-resistant KMT2A::AFF1+ B-ALL cells showed upregulation of genes associated with a myeloid immunophenotype, including CD33, LILRB4/CD85k, MPEG1, CCL5, and LIMK1. Taken together, we here present a valuable model to study the adaptive potential of KMT2A-rearranged ALL upon losing dependency on one of its main oncogenic properties.
Project description:KMT2A-rearranged acute lymphoblastic leukemia (ALL) is an aggressive type of leukemia which represents the most common form diagnosed in infancy. Oncogenic KMT2A-fusion proteins recruit histone methyltransferase DOT1L which leads to misplaced H3K79 methylation inducing an abnormal transcriptomic landscape that favors leukemia development. Hence, inhibition of DOT1L represents an attractive therapeutic strategy. Unfortunately, the first-in-class DOT1L inhibitor pinometostat resulted in the development of resistance. To understand this resistance we established acquired resistance to DOT1L inhibition in a pediatric KMT2A::AFF1+ B-ALL cell line model that stably became ~35-fold more resistant to pinometostat. Interestingly, while becoming almost completely independent of DOT1L-mediated H3K79 methylation, these cells remained fully dependent on the physical presence of DOT1L, HOXA9, as well as the KMT2A::AFF1 fusion protein. Further characterization of these cells using RNA-, ChIP-, and ATAC-sequencing analyses revealed that acquired resistance to DOT1L inhibition leads to a selective loss of KMT2A-fusion driven epigenetic regulation and expression of genes such as PROM1 (encoding the hematopoietic/leukemia stem cell marker CD133) and its enhancer TAPT1, as well as other putative KMT2A::AFF1 target genes such as RUNX2, PRSS12, ZC3H12, and GNAQ. In contrast, the levels of H3K79me2 and expression of other KMT2A::AFF1 target genes, including HOXA9, MEIS1, and CDK6 remained unaffected. Concomitantly, pinometostat-resistant KMT2A::AFF1+ B-ALL cells showed upregulation of genes associated with a myeloid immunophenotype, including CD33, LILRB4/CD85k, MPEG1, CCL5, and LIMK1. Taken together, we here present a valuable model to study the adaptive potential of KMT2A-rearranged ALL upon losing dependency on one of its main oncogenic properties.
Project description:KMT2A-rearranged acute lymphoblastic leukemia (ALL) is an aggressive type of leukemia which represents the most common form diagnosed in infancy. Oncogenic KMT2A-fusion proteins recruit histone methyltransferase DOT1L which leads to misplaced H3K79 methylation inducing an abnormal transcriptomic landscape that favors leukemia development. Hence, inhibition of DOT1L represents an attractive therapeutic strategy. Unfortunately, the first-in-class DOT1L inhibitor pinometostat resulted in the development of resistance. To understand this resistance we established acquired resistance to DOT1L inhibition in a pediatric KMT2A::AFF1+ B-ALL cell line model that stably became ~35-fold more resistant to pinometostat. Interestingly, while becoming almost completely independent of DOT1L-mediated H3K79 methylation, these cells remained fully dependent on the physical presence of DOT1L, HOXA9, as well as the KMT2A::AFF1 fusion protein. Further characterization of these cells using RNA-, ChIP-, and ATAC-sequencing analyses revealed that acquired resistance to DOT1L inhibition leads to a selective loss of KMT2A-fusion driven epigenetic regulation and expression of genes such as PROM1 (encoding the hematopoietic/leukemia stem cell marker CD133) and its enhancer TAPT1, as well as other putative KMT2A::AFF1 target genes such as RUNX2, PRSS12, ZC3H12, and GNAQ. In contrast, the levels of H3K79me2 and expression of other KMT2A::AFF1 target genes, including HOXA9, MEIS1, and CDK6 remained unaffected. Concomitantly, pinometostat-resistant KMT2A::AFF1+ B-ALL cells showed upregulation of genes associated with a myeloid immunophenotype, including CD33, LILRB4/CD85k, MPEG1, CCL5, and LIMK1. Taken together, we here present a valuable model to study the adaptive potential of KMT2A-rearranged ALL upon losing dependency on one of its main oncogenic properties.
Project description:The histone methyltransferases DOT1L (H3K79me1,2,3 KMT, "activating" chromatin mark) and EZH2 (H3K27me1,2,3 KMT, "silencing" mark) have both been shown to be required for growth and survival of KMT2A rearranged AML cells. Both KMTs have been shown to modulate expression of HOXA cluster genes, albeit for EZH2 this has not been shown in the context of KMT2A rearranged AML, but in other subtypes of AML. We asked what transcriptional effects dual inhibition of DOT1L and EZH2 has in KMT2A rearranged AML.