Project description:Cooperation of MLL/AF10 with RAS pathway mutations accelerated myeloid leukemia development. The detail molecular mechanism is analyzed by identification of the differentially expressed genes between MLL/AF10 cells harboring wild-type and mutant RAS pathway genes and by with or without Hoxa11. We used cDNA microarray to compare transcriptomes between mouse MLL/AF10 myeloid leukemia cells harboring wild-type KRAS and harboring KRAS-G12C (AKw1G and AK3G), or between MLL/AF10 cells harboring wild-type PTPN11 and harboring PTPN11-G503A (APw-1 and APm-1), or between MLL/AF10 cells without and with Hoxa11 (12G-V and 12G-H11).
Project description:MLL fusion proteins in leukemia induce aberrant transcriptional elongation and associated chromatin perturbations, however the upstream signaling pathways and activators that recruit or retain MLL oncoproteins at initiated promoters are unknown. Through functional and comparative genomic studies, we identified an essential role for NF-kB signaling in MLL leukemia. Suppression of NF-kB led to robust anti-leukemia effects that phenocopied loss of functional MLL oncoprotein or associated epigenetic cofactors. The NF-kB subunit RELA occupies promoter regions of crucial MLL target genes and sustains the MLL-dependent leukemia stem cell program. IKK/NF-kB signaling is required for wild-type MLL and fusion protein retention and maintenance of associated histone modifications providing a molecular rationale for enhanced efficacy in therapeutic targeting of this pathway in MLL leukemias. MLL-AF10 cells were treated with 0.5µM IKK inhibitor or vehicle. Each group contains triplicate samples.
Project description:Purpose: The goals of this study are to compare transcriptomes after shutting off the CALM-AF10, MLL-AF10 and MLL-AF9 fusion proteins in mouse AML cells. Furthermore, we also perform transcriptomic experiments to assess the changes in transcripts upon JAK1 deletion in mouse CALM-AF10 AML. Methods: Mouse AMLs cells grown in Mouse leukemia medium (see below) were treated with DMSO (Tet-On) or 4ug/ul Doxycycline (Tet-Off) and RNA was isolated to perform RNA-seq. RNA for CALM-AF10, MLL-AF10 was poly-A selected and MLL-AF9, total RNA was used to make RNAseq libraries using the NEB RNAseq lbrary prep kit. The sequence reads that passed quality filters were analyzed at the transcript isoform level with two methods: Burrows–Wheeler Aligner (BWA) followed by ANOVA (ANOVA) and TopHat followed by Cufflinks. qRT–PCR validation was performed using TaqMan and SYBR Green assays Results: Using an optimized data analysis workflow, we mapped about 20 million sequence reads per sample to the mouse genome (build mm9) and 60 million reads for MLL-AF9 data. Data analysis with BWA and TopHat workflows revealed genes that are significantly changed after shutting off the fusions or after deleting Jak1 in CALM-AF10 Jak1 floxed cells using the Cre recombinase. Conclusions:
Project description:MLL fusion proteins in leukemia induce aberrant transcriptional elongation and associated chromatin perturbations, however the upstream signaling pathways and activators that recruit or retain MLL oncoproteins at initiated promoters are unknown. Through functional and comparative genomic studies, we identified an essential role for NF-kB signaling in MLL leukemia. Suppression of NF-kB led to robust anti-leukemia effects that phenocopied loss of functional MLL oncoprotein or associated epigenetic cofactors. The NF-kB subunit RELA occupies promoter regions of crucial MLL target genes and sustains the MLL-dependent leukemia stem cell program. IKK/NF-kB signaling is required for wild-type MLL and fusion protein retention and maintenance of associated histone modifications providing a molecular rationale for enhanced efficacy in therapeutic targeting of this pathway in MLL leukemias. MV4;11 cells were treated with 1µM IKK inhibitor or vehicle. Each group contains triplicate samples
Project description:Background: MLL (KMT2A)-EB1 (MAPRE1) fusion was identified in a patient with de novo pro-B acute lymphoblastic leukemia. To investigate the leukemogenesis of MLL-EB1 fusion, a retroviral transduction of MLL-EB1 to murine bone marrow cells was performed. A frequent MLL fusion, MLL-AF10(OM-LZ), was used as a positive control. Results: Two MLL-EB1 immortalized cell lines (ME1 and ME2G), and a MLL-AF10(OM-LZ) immortalized cell line (12G) were generated. Microarray results showed that many genes including Evi1 and Ets1 were differentially expressed in ME1/ME2G and 12G cell lines.
Project description:Leukemia cells from mice with MLL-AF10 AML were fractionated into separate sub-populations on the basis of c-kit expression, which correlates with MLL LSC frequency (Somervaille and Cleary, 2006). The sorted AML sub-populations exhibited substantial differences in their frequencies of AML CFCs/LSCs (mean 14-fold) and morphologic features, consistent with a leukemia cell hierarchy with maturation through to terminally differentiated neutrophils. Experiment Overall Design: Leukemic splenocytes from four mice with MLL-AF10 AML were sub-fractionated in to c-kit high and c-kit negative sub-populations by FACS.
Project description:Acute myeloid leukemia (AML), a heterogeneous hematologic malignancy, is the most common form of acute leukemia in adults. MLL rearrangements (MLL-r) are observed in approximately 10% of AML and are associated with a relatively poor prognosis, highlighting the need for new treatment regimens. MLL fusions recruit KDM4C to mediate epigenetic reprogramming, which is required for maintenance of MLL-r leukemia. In this study, we used a combinatorial drug screen to selectively identify synergistic treatment partners for the KDM4C inhibitor SD70. The results showed that the drug combination of SD70 and MI-503, a potent Menin-MLL inhibitor, induced synergistically enhanced apoptosis in MLL-r leukemia cells without affecting normal CD34+ cells. In vivo treatment with SD70 and MI-503 significantly prolongs survival in AML xenograft models. Differential Gene expression analysis by RNA-seq following combined pharmacological inhibition of SD70 and MI-503 revealed changes in numerous genes, with MYC target genes being the most significantly downregulated. Taken together, these data provide preclinical evidence that the combination of SD70 and MI-503 is a potential dual-target therapy for MLL-r AML.
Project description:Chromosome translocations involving the MLL gene are common rearrangements in leukemia. Such translocations fuse the MLL 5’-region in frame to partner genes , and the resultant fusion proteins can cause MLL-related leukemia. MLL-fusions activate transcription of target genes such as the HoxA cluster and Meis1, but the underlying mechanisms remain elusive. We found that the MLL-AF10 fusion recruits Tip60 to the Hoxa9 locus, where it acetylates H2A.Z, thereby promoting Hoxa9 expression. Following conditional deletion of Tip60, hypoacetylation of H2A.Z was accompanied by recruitment of Ezh2, the catalytic subunit of PRC2, suggesting that nucleosomes with hypoacetylated H2A.Z are the preferential targets of Ezh2. Our findings suggest that MLL-AF10 achieves active chromatin states by recruiting Tip60, which acetylates H2A.Z to prevent gene silencing by Ezh2.