0000000000178949
AUTHOR
Scott A. Armstrong
MLL-Rearranged Leukemia Is Dependent on Aberrant H3K79 Methylation by DOT1L
SummaryThe histone 3 lysine 79 (H3K79) methyltransferase Dot1l has been implicated in the development of leukemias bearing translocations of the Mixed Lineage Leukemia (MLL) gene. We identified the MLL-fusion targets in an MLL-AF9 leukemia model, and conducted epigenetic profiling for H3K79me2, H3K4me3, H3K27me3, and H3K36me3 in hematopoietic progenitor and leukemia stem cells (LSCs). We found abnormal profiles only for H3K79me2 on MLL-AF9 fusion target loci in LSCs. Inactivation of Dot1l led to downregulation of direct MLL-AF9 targets and an MLL translocation-associated gene expression signature, whereas global gene expression remained largely unaffected. Suppression of MLL translocation-a…
Synergistic targeting of FLT3 mutations in AML via combined menin-MLL and FLT3 inhibition
Abstract The interaction of menin (MEN1) and MLL (MLL1, KMT2A) is a dependency and provides a potential opportunity for treatment of NPM1-mutant (NPM1mut) and MLL-rearranged (MLL-r) leukemias. Concomitant activating driver mutations in the gene encoding the tyrosine kinase FLT3 occur in both leukemias and are particularly common in the NPM1mut subtype. In this study, transcriptional profiling after pharmacological inhibition of the menin-MLL complex revealed specific changes in gene expression, with downregulation of the MEIS1 transcription factor and its transcriptional target gene FLT3 being the most pronounced. Combining menin-MLL inhibition with specific small-molecule kinase inhibitors…
Combined Targeting of the Menin-MLL1 Chromatin Complex and FLT3 As a Novel Therapeutic Concept Against NPM1 Mutant or MLL-Rearranged AML with Mutated FLT3
NPM1mutant (NPM1mut) and MLL1-rearranged (MLL-r) acute myeloid leukemias (AMLs) exhibit aberrant expression of HOX and MEIS1 transcription factors and commonly harbor an activating mutation in the receptor tyrosine kinase FLT3. Pharmacologic inhibition of the menin-MLL1 complex reverses leukemogenic gene expression including MEIS1 and FLT3 and represents a therapeutic opportunity for the treatment of these leukemias. Here, we investigate the contribution of the menin-MLL1 complex to leukemic FLT3 signaling and assess the therapeutic potential of dual menin-MLL1 and FLT3 targeting. First, we performed RNA sequencing to delineate transcriptional changes associated with menin-MLL1 inhibition (…
Demonstration of a Role for Dot1l In MLL-Rearranged Leukemia Using a Conditional Loss of Function Model
Abstract Abstract 62 Leukemias associated with translocations of the Mixed Lineage Leukemia (MLL) gene account for a significant percentage of both AML and ALL, and often carry a poor prognosis. The exact molecular mechanisms by which MLL-fusion proteins transform cells are incompletely understood. One proposed model involves the aberrant activation of transcriptional programs through epigenetic changes that ultimately lead to leukemogenesis. The histone 3 lysine 79 (H3K79) methyltransferase Dot1l has been shown to be recruited by the most common MLL fusion proteins, and MLL fusion protein target loci are associated with H3K79 methylation (H3K79me2/3) in mouse models and MLL-rearranged huma…