Project description:The miR-155-dependent differences in gene expression in the HSPC compartment of FLT3-ITD mice is unknown. In this experiment, we performed RNA sequencing on FLT3-ITD and FLT3-ITD miR-155-/- mouse LKS cells.
Project description:The expression profile in miR-155-/- FLT3-ITD+ AML is unknown. Using empty vector (EV) or two distinct miR-155 (S3 or S10) lentiviral CRISPR-Cas9 infected FLT3-ITD+ AML cell lines (MV4-11 cells), we performed next generation RNA sequencing to determine the expression profile in these cells dependent on miR-155. We found a number of pathways dysregulated, including STAT5 activation.
Project description:The expression profile in miR-155-/- FLT3-ITD+ AML is unknown. Using empty vector (EV) or two distinct miR-155 (S3 or S10) lentiviral CRISPR-Cas9 infected FLT3-ITD+ AML cell lines (MV4-11 cells), we performed next generation RNA sequencing to determine the expression profile in these cells dependent on miR-155. We found a number of pathways dysregulated, including STAT5 activation. RNAseq was performed on EV or miR-155 lentiviral CRISPR-Cas9 infected MV4-11 cell lines in triplicate cultures.
Project description:FLT3 activating mutations cause myeloproliferative neoplasms by deregulating hematopoietic progenitor cell growth, and acute myeloid leukemia is on the rise. Investigational drugs targeting mutant FLT3, including Quizartinib and Crenolanib, develop inherent and acquired resistance to FLT3 targeted therapy. FLT3 inhibitor resistance in AML is dependent on co-occurring mutations, parallel survival pathways, and/or subsequent FLT3-ITD mutations. Despite the high prevalence of FLT3 mutations and their clinical significance in AML, there are few targeted therapeutic options. We identified two novel naphthyridine-based FLT3 inhibitors (HSN608 and HSN748) that specifically target FLT3-ITD at sub-nanomolar concentrations and are effective against drug-resistant secondary mutations. In the current study, we evaluated these compounds antileukemic activity against FLT3-ITD and gatekeeper mutations in drug-resistant AML, relapsed/refractory AMLs with FLT3 mutations, and in vivo mouse models with combinations of epigenetic mutations TET2 with FLT3-ITD, and AML patients PDX. In these model systems, we demonstrate that HSN748 outperforms the FDA-approved FLT3 inhibitor Gilteritinib in terms of inhibitory activity against FLT3-ITD.
Project description:Acute myeloid leukemia (AML) carrying NPM1 mutations and cytoplasmic nucleophosmin (NPMc+ AML) accounts for about one-third of adult AML and shows distinct features, including a unique gene expression profile. MicroRNAs (miRNAs) are small noncoding RNAs of 19-25 nucleotides in length that have been linked to the development of cancer. Here, we investigated the role of miRNAs in the biology of NPMc+ AML. The miRNA expression was evaluated in 85 adult de novo AML patients characterized for subcellular localization/mutation status of NPM1 and FLT3 mutations using a custom microarray platform. Data were analyzed by using univariate t test within BRB tools. We identified a strong miRNA signature that distinguishes NPMc+ mutated (n = 55) from the cytoplasmic-negative (NPM1 unmutated) cases (n = 30) and includes the up-regulation of miR-10a, miR-10b, several let-7 and miR-29 family members. Many of the down-regulated miRNAs including miR-204 and miR-128a are predicted to target several HOX genes. Indeed, we confirmed that miR-204 targets HOXA10 and MEIS1, suggesting that the HOX up-regulation observed in NPMc+ AML may be due in part by loss of HOX regulators-miRNAs. FLT3-ITD+ samples were characterized by up-regulation of miR-155. Further experiments demonstrated that the up-regulation of miR-155 was independent from FLT3 signaling. Our results identify a unique miRNA signature associated with NPMc+ AML and provide evidence that support a role for miRNAs in the regulation of HOX genes in this leukemia subtype. Moreover, we found that miR-155 was strongly but independently associated with FLT3-ITD mutations.
Project description:We recently showed that exosomes from primary AML cells and cell lines have potent regulatory capacity and we hypothesized that leukemia cell exosome trafficking might account for the suppression of residual hematopoietic stem and progenitor cells (HSPC) in the leukemic niche. Here we studied Molm-14 cells in in vitro experiments using purified exosomes under carefully calibrated low-oxygen conditions. This approach revealed the active regulation of stromal- and hematopoietic progenitor cell function. Systematic analysis of AML exosomes identified a panel of differentially enriched hypoxia-responsive miRNAs, including miR-210, -155, and -146a.
Project description:Hematopoietic stem/progenitor cell (HSPC) traits differ between genetically distinct mouse strains. For example, DBA/2 mice have a higher HSPC frequency compared to C57BL/6 mice. We performed a genetic screen for microRNAs that are differentially expressed between LSK, LS−K+, erythroid and myeloid cells isolated from C57BL/6 and DBA/2 mice. This analysis identified 131 microRNAs that were differentially expressed between cell types and 15 that were differentially expressed between mouse strains. Of special interest was an evolutionary conserved miR-cluster located on chromosome 17 consisting of miR-99b, let-7e and miR-125a. All cluster members were most highly expressed in LSKs and down-regulated upon differentiation. In addition, these microRNAs were higher expressed in DBA/2 cells compared to C57BL/6 cells, and thus correlated with HSPC frequency. To functionally characterize these microRNAs, we overexpressed the entire miR-cluster 99b/let-7e/125a and miR-125a alone in BM cells from C57BL/6 mice. Overexpression of the miR-cluster or miR-125a dramatically increased day-35 CAFC activity and caused severe hematopoietic phenotypes upon transplantation. We showed that a single member of the miR-cluster, namely miR-125a, is responsible for the majority of the observed miR-cluster overexpression effects. Finally, we performed genome-wide gene expression arrays and identified candidate target genes through which miR-125a may modulate HSPC fate. These data consist of total mRNA obtained from 7-day cultured post 5-FU BM cells positively transduced with empty vector, miR-cluster 99b/let-7e/125a, miR-125a or miR-155 retroviral vector. Dataset (A) and dataset (B) were analyzed individualy. In each dataset, all samples were analyzed in independent biological triplicates.
Project description:Internal tandem duplications in the tyrosine kinase receptor FLT3 (FLT3-ITD) are among the most common lesions in acute myeloid leukemia (AML) and there exists a need for new forms of treatment. Using ex vivo drug sensitivity screening, we found that FLT3-ITD+ patient cells are particularly sensitive to HSP90 inhibitors. While it is well known that HSP90 is important for FLT3-ITD stability, we found that HSP90 family members play a much more complex role in FLT3-ITD signaling than previously appreciated. First, we found that FLT3-ITD activates the unfolded protein response (UPR), leading to increased expression of GRP94/HSP90B1. GRP94 rewires FLT3-ITD signaling by binding and retaining FLT3-ITD in the ER, where it aberrantly activates downstream signaling pathways. Second, HSP90 family proteins protect FLT3-ITD+ AML cells against apoptosis by alleviating proteotoxic stress, and treatment with HSP90 inhibitors results in proteotoxic overload that triggers UPR-induced apoptosis. Importantly, leukemic stem cells are strongly dependent upon HSP90 for their survival, and the HSP90 inhibitor ganetespib causes leukemic stem cell exhaustion in mouse PDX models. Taken together, our study reveals a molecular basis for HSP90 addiction of FLT3-ITD+ AML cells and provides a rationale for including HSP90 inhibitors in the treatment regime for FLT3-ITD+ AML.
Project description:We studied the chromatin modification patterns induced by the presence of the MLL-AF9 fusion protein in a model of human hematopoietic stem/progenitor cells (HSPC) transduced with retrovirus expressing MLL-AF9cDNA (HSPC-MA9). Comparative ChIP-seq analysis between HSPC-MA9 and control HSPC, revealed a massive hyperacetylation of histones that was consistent with the transcriptional profile in the presence of MLL-AF9 fusion protein. Furthermore, we identified 66 MLL-AF9 targets, and found that H4ac was present along with H3K4me3 and H3K79me2 chromatin marks in over 50% of the MLL-AF9 target genes. Examination of histone aceylation and methylation changes upon expression of MLL-AF9 fusion protein in human hematopoietic stem/progenitor cells.
Project description:Cohesin complex members have recently been identified as putative tumor suppressors in hematologic and epithelial malignancies. The cohesin complex guides chromosome segregation, however cohesin-mutant leukemias do not show genomic instability. We hypothesized reduced cohesin function alters chromatin structure and disrupts cis-regulatory architecture of hematopoietic progenitors. We investigated the consequences of Smc3 deletion in normal and malignant hematopoiesis. Bi-allelic Smc3 loss induced bone marrow aplasia with premature sister chromatid separation, and revealed an absolute requirement for cohesin in hematopoietic stem cell function. In contrast, Smc3 haploinsufficiency increased self-renewal in vitro and in vivo including competitive transplantation. Smc3 haploinsufficiency reduced coordinated transcriptional output, including reduced expression of transcription factors and other genes associated with lineage commitment. Smc3 haploinsufficiency cooperated with Flt3-ITD to induce acute leukemia in vivo, with potentiated Stat5 signaling and altered nucleolar topology. These data establish a dose-dependency for cohesin in regulating chromatin structure and hematopoietic stem cell function. ATAC-seq in murine c-kit+ cells for the following genotypes: Smc3 fl/+, Smc3 del/+, Flt3-ITD, Smc3 fl/del Flt3-ITD