Project description:Transcriptional profiling of transformed Ba/F3 cells by myeloproliferative neoplasm-associated JAK2 V617F mutant comparing control Ba/F3 cells expressing wild type JAK2. Two-condition experiment, WT cells vs. VF cells. One replicate per array.
Project description:Pegylated interferon alpha (pegIFNα) can induce molecular remissions in JAK2-V617F-positive myeloproliferative neoplasms (MPN) patients by targeting long-term hematopoietic stem cells (LT-HSCs). Additional somatic mutations in genes regulating LT-HSC self-renewal, such as DNMT3A, have been reported to have poorer responses to pegIFNα. We investigated if DNMT3A loss leads to alterations in JAK2-V617F LT-HSCs functions conferring resistance to pegIFNα treatment in a mouse model of MPN and in hematopoietic progenitors from MPN patients. Long-term treatment with pegIFNα normalized blood parameters, reduced splenomegaly and JAK2-V617F-chimerism in single-mutant JAK2-V617F (VF) mice. However, pegIFNα in VF;Dnmt3aΔ/Δ (VF;DmΔ/Δ) mice worsened splenomegaly and failed to reduce JAK2-V617F-chimerism. Furthermore, LT-HSCs from VF;DmΔ/Δ mice compared to VF were less prone to accumulate DNA damage and exit dormancy upon pegIFNα treatment. RNA-sequencing showed that IFNα induced stronger upregulation of inflammatory pathways in LT-HSCs from VF;DmΔ/Δ compared to VF mice, indicating that the resistance of VF;DmΔ/Δ LT-HSC was not due to failure in IFNα signaling. Transplantations of bone marrow from pegIFNα treated VF;DmΔ/Δ mice gave rise to more aggressive disease in secondary and tertiary recipients. Liquid cultures of hematopoietic progenitors from MPN patients with JAK2-V617F and DNMT3A mutation showed increased percentages of JAK2-V617F-positive colonies upon IFNα exposure, whereas in patients with JAK2-V617F alone the percentages of JAK2-V617F-positive colonies decreased or remained unchanged. PegIFNα combined with 5-azacytidine only partially overcame resistance in VF;DmΔ/Δ mice. However, this combination strongly decreased the JAK2-mutant allele burden in mice carrying VF mutation only, showing potential to inflict substantial damage preferentially to the JAK2-mutant clone.
Project description:SPAG9-JAK2 is a novel fusion gene identified in a pediatric patient with Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL). In this study, we performed functional analysis of the SPAG9-JAK2 fusion to establish molecular targeted therapy. Ba/F3 cells expressing SPAG9-JAK2 generated by retroviral transduction (Ba/F3-SPAG9-JAK2), proliferated in the absence of IL-3, and exhibited constitutive phosphorylation of the tyrosine residues in the JAK2 kinase domain of the fusion protein and STAT3/STAT5. Mutation of tyrosine residues in the JAK2 kinase domain (SPAG9-JAK2 mut) abolished IL-3 independence, but had no influence on STAT3/STAT5 phosphorylation levels. Gene expression analysis revealed that Stat1 was significantly up-regulated in Ba/F3-SPAG9-JAK2 cells. STAT1 was also phosphorylated in Ba/F3-SPAG9-JAK2 but not SPAG9-JAK2 mut cells, suggesting that STAT1 is key for SPAG9-JAK2-mediated cell proliferation. Consistently, STAT1 induced expression of the anti-apoptotic proteins, BCL-2 and MCL-1, as did SPAG9-JAK2, but not SPAG9-JAK2 mut. Ruxolitinib abrogated Ba/F3-SPAG9-JAK2-mediated proliferation in vitro, but was insufficient in vivo. Venetoclax (a BCL-2 inhibitor) or AZD5991 (an MCL-1 inhibitor) enhanced the effects of ruxolitinib on Ba/F3-SPAG9-JAK2 in vitro. These findings suggest that activation of the JAK2-STAT1-BCL-2/MCL-1 axis contributes to SPAG9-JAK2-related aberrant growth promotion. BCL-2 or MCL-1 inhibition is a potential therapeutic option for B-ALL with SPAG9-JAK2 fusion.
Project description:JAK2-V617F is the most frequent somatic mutation causing myeloproliferative neoplasm (MPN). JAK2-V617F can be found in healthy individuals with clonal hematopoiesis of indeterminate potential (CHIP) with a frequency much higher than the prevalence of MPN. The factors controlling the conversion of JAK2-V617F CHIP to MPN are largely unknown. We hypothesized that IL-1β mediated inflammation can favor this progression. We established an experimental system using bone marrow (BM) transplantations from JAK2-V617F and GFP transgenic (VF;GFP) mice, that were further crossed with IL-1β-/- or IL-1R1-/- mice. To study the role of IL-1β and its receptor on monoclonal evolution of MPN, we performed competitive BM transplantations at high dilutions with only 1-3 hematopoietic stem cells (HSCs) per recipient. Loss of IL-1β in JAK2-mutant HSCs reduced engraftment, restricted clonal expansion, lowered the total numbers of functional HSCs, and decreased the rate of conversion to MPN. Loss of IL-1R1 in the recipients also lowered the conversion to MPN, but did not reduce the frequency of engraftment of JAK2-mutant HSCs. WT recipients transplanted with VF;GFP BM that developed MPN had elevated IL-1β levels and reduced frequencies of mesenchymal stromal cells (MSCs). Interestingly, frequencies of MSCs were also reduced in recipients that did not develop MPN, had only marginally elevated IL-1β levels and displayed low GFP-chimerism resembling CHIP. Anti-IL-1β antibody preserved high frequencies of MSCs in VF;GFP recipients and reduced the rate of engraftment and the conversion to MPN. Our results identify IL-1β as a potential therapeutic target for preventing the transition from JAK2-V617F CHIP to MPN.
Project description:The activation of PD-1 (Programmed Death receptor-1) on T cells can cause T cell exhaustion and immune tolerance. Some tumors up-regulate the expression of the ligand of PD-1, namely PD-L1 (Programmed Death Receptor-Ligand 1), thus preventing anti-tumor immune response and promoting immune-escape. Previous studies have shown that JAK2 (Janus Kinase 2) signaling can promote PD-L1 expression in Hodgkin Lymphoma. In Myeloproliferative Neoplasms (MPN), JAK2 is frequently characterized by the the presence of the point-mutation V617F, which leads to its constitutive activation and to uncontrolled cell proliferation and survival. Accordingly, tumor cell lines expressing JAK2 V617F express higher levels of PD-L1 as compared to tumor cell lines negative for such mutations. In this experiment, we transfected BaF3 cells with a vector (plasmid for Murine Stem Cell Virus) containing the gene for JAK2 with the point-mutation V617F. As control, we used BaF3 cells transfected with the same vector, but without the gene for JAK2 V617F (empty vector). Both the cell lines (with/without JAK2 V617F) were co-cultured with primary murine T cells. When co-cultured with BaF3 cells expressing JAK2 V617F, T cells upregulated genes connected to senescence pathways, showed increased apoptosis, less cytokine production, and displayed other forms of dysfunction which can be associated with the activation of PD-1.
Project description:Transplant recipients of IDH2-R140Q JAK2-V617F expressing bone marrow were treated with AG221 and ruxolitinib monotherapy, combined therapy, or vehicle. LSKs were sorted from terminal samples and sequenced with three WT controls.
Project description:Gene expression profiles in Ba/F3 cells expressing ETV6-PDGFRB, FIP1L1-PDGFRA or a control vector, treated or not with imatinib (Glivec) Ba/F3 cells expressing FIP1L1-PDGFRA or ETV6-PDGFRB were cultured in the presence or absence of imatinib for 4 hours before RNA extraction followed by hybridization on Affymetrix microarrays. In a control condition Ba/F3 cells were cultured in the presence of IL3 in the absence or in the presence of imatinib for 4 hours before RNA extraction. 4 hours treatment with imatinib in Ba/F3 cells expressing ETV6-PDGFRB, FIP1L1-PDGFRA or a control vector
Project description:The JAK2 mutation V617F is detectable in a majority of patients with Ph-negative myeloproliferative neoplasms (MPN). Enforced expression of JAK2 V617F in mice induces myeloproliferation and bone marrow (BM) fibrosis suggesting a causal role for the JAK2 mutant in the pathogenesis of MPN. However, little is known about mechanisms and effector molecules contributing to JAK2 V617F-induced myeloproliferation and fibrosis. Here we show that JAK2 V617F promotes expression of oncostatin M (OSM) in neoplastic myeloid cells. Correspondingly, OSM was found to be overexpressed in the BM and elevated in the serum of patients with JAK2 V617F+ MPN. In addition, OSM secreted by JAK2 V617F+ cells stimulated growth of fibroblasts and microvascular endothelial cells and induced the production of angiogenic and profibrogenic cytokines (HGF, VEGF, and SDF-1) in BM fibroblasts. All effects of MPN cell-derived OSM were blocked by a neutralizing anti-OSM antibody, whereas the production of OSM in MPN cells was effectively suppressed by a pharmacologic JAK2 inhibitor or RNAi-mediated knockdown of JAK2. In summary, JAK2 V617F-mediated upregulation of OSM may contribute to fibrosis, neoangiogenesis, and the cytokine storm observed in JAK2 V617F+ MPN, suggesting that OSM could serve as a novel therapeutic target molecule in these neoplasms. IMR90 cells were treated with a single dose of rh Oncostatin M (10ng/ml).