BRD3/4 inhibition and FLT3-ligand deprivation target pathways that are essential for the survival of human MLL-AF9+ leukemic cellsCarretta, M., Brouwers-Vos, A. Z., Bosman, M., Horton, S. J., Martens, J. H. A., Vellenga, E. & Schuringa, J. J., 14-Dec-2017, In : PLoS ONE. 12, 12, 18 p., e0189102.
Research output: Contribution to journal › Article › Academic › peer-review
In the present work we aimed to identify targetable signaling networks in human MLL-AF9 leukemias. We show that MLL-AF9 cells critically depend on FLT3-ligand induced pathways as well as on BRD3/4 for their survival. We evaluated the in vitro and in vivo efficacy of the BRD3/4 inhibitor I-BET151 in various human MLL-AF9 (primary) models and patient samples and analyzed the transcriptome changes following treatment. To further understand the mode of action of BRD3/4 inhibition, we performed ChIP-seq experiments on the MLL-AF9 complex in THP1 cells and compared it to RNA-seq data of I-BET151 treated cells. While we could confirm a consistent and specific downregulation of key-oncogenic drivers such as MYC and BCL2, we found that the majority of I-BET151-responsive genes were not direct MLL-AF9 targets. In fact, MLL-AF9 specific targets such as the HOXA cluster, MEIS1 and other cell cycle regulators such as CDK6 were not affected by I-BET151 treatment. Furthermore, we also highlight how MLL-AF9 transformed cells are dependent on the function of non-mutated hematopoietic transcription factors and tyrosine kinases such as the FLT3TAK1/ NF-kB pathway, again impacting on BCL2 but not on the HOXA cluster. We conclude that BRD3/4 and the FLT3-TAK1/NF-kB pathways collectively control a set of targets that are critically important for the survival of human MLL-AF9 cells.
|Number of pages||18|
|Publication status||Published - 14-Dec-2017|
- ACUTE MYELOID-LEUKEMIA, NF-KAPPA-B, HEMATOPOIETIC STEM-CELL, LONG-TERM EXPANSION, EX-VIVO ASSAYS, SELF-RENEWAL, TRANSCRIPTIONAL ELONGATION, THERAPEUTIC TARGET, BET BROMODOMAINS, BRD4