Project description:Myeloproliferative neoplasms (MPN) transform to myelofibrosis (MF) and highly lethal acute myeloid leukemia (AML), although actionable mechanisms driving progression remain elusive. The HMGA1 chromatin regulator is up-regulated during MPN progression with highest levels after transformation. HMGA1 depletion in JAK2V617F MPN AML cell lines disrupts proliferation, clonogenicity, and leukemic engraftment. Surprisingly, loss of just a single Hmga1 allele prevents progression to MF in JAK2V617F transgenic mice, decreasing blood counts and expansion in stem and myeloid progenitors while preventing splenomegaly and fibrosis within the spleen and bone marrow. RNA sequencing revealed HMGA1-dependent transcriptional networks that govern proliferation (E2F, G2M, mitosis, MYC targets) and cell fate, including the GATA2 master regulatory gene. Silencing GATA2 recapitulates phenotypes observed with HMGA1 depletion whereas GATA2 re-expression partially rescues leukemogenesis. HMGA1 transactivates GATA2 through sequences near the developmental enhancer (+9.5), increasing chromatin accessibility and recruiting active histone marks. Further, HMGA1 transcriptional networks, including GATA2, are activated in human MF after leukemic transformation. Further, HMGA1 depletion synergizes with the JAK2 inhibitor, ruxolitinib, to prolong survival in murine MPN AML. These findings illuminate HMGA1 as a key epigenetic switch required for MPN transformation and promising therapeutic target to treat or prevent disease progression.
Project description:Myeloproliferative neoplasms (MPN) transform to myelofibrosis (MF) and highly lethal acute myeloid leukemia (AML), although actionable mechanisms driving progression remain elusive. The HMGA1 chromatin regulator is up-regulated during MPN progression with highest levels after transformation. HMGA1 depletion in JAK2V617F MPN AML cell lines disrupts proliferation, clonogenicity, and leukemic engraftment. Surprisingly, loss of just a single Hmga1 allele prevents progression to MF in JAK2V617F transgenic mice, decreasing blood counts and expansion in stem and myeloid progenitors while preventing splenomegaly and fibrosis within the spleen and bone marrow. RNA sequencing revealed HMGA1-dependent transcriptional networks that govern proliferation (E2F, G2M, mitosis, MYC targets) and cell fate, including the GATA2 master regulatory gene. Silencing GATA2 recapitulates phenotypes observed with HMGA1 depletion whereas GATA2 re-expression partially rescues leukemogenesis. HMGA1 transactivates GATA2 through sequences near the developmental enhancer (+9.5), increasing chromatin accessibility and recruiting active histone marks. Further, HMGA1 transcriptional networks, including GATA2, are activated in human MF after leukemic transformation. Further, HMGA1 depletion synergizes with the JAK2 inhibitor, ruxolitinib, to prolong survival in murine MPN AML. These findings illuminate HMGA1 as a key epigenetic switch required for MPN transformation and promising therapeutic target to treat or prevent disease progression.
Project description:Myeloproliferative neoplasms (MPN) transform to myelofibrosis (MF) and highly lethal acute myeloid leukemia (AML), although actionable mechanisms driving progression remain elusive. The HMGA1 chromatin regulator is up-regulated during MPN progression with highest levels after transformation. HMGA1 depletion in JAK2V617F MPN AML cell lines disrupts proliferation, clonogenicity, and leukemic engraftment. Surprisingly, loss of just a single Hmga1 allele prevents progression to MF in JAK2V617F transgenic mice, decreasing blood counts and expansion in stem and myeloid progenitors while preventing splenomegaly and fibrosis within the spleen and bone marrow. RNA sequencing revealed HMGA1-dependent transcriptional networks that govern proliferation (E2F, G2M, mitosis, MYC targets) and cell fate, including the GATA2 master regulatory gene. Silencing GATA2 recapitulates phenotypes observed with HMGA1 depletion whereas GATA2 re-expression partially rescues leukemogenesis. HMGA1 transactivates GATA2 through sequences near the developmental enhancer (+9.5), increasing chromatin accessibility and recruiting active histone marks. Further, HMGA1 transcriptional networks, including GATA2, are activated in human MF after leukemic transformation. Further, HMGA1 depletion synergizes with the JAK2 inhibitor, ruxolitinib, to prolong survival in murine MPN AML. These findings illuminate HMGA1 as a key epigenetic switch required for MPN transformation and promising therapeutic target to treat or prevent disease progression.
Project description:Myeloproliferative neoplasms (MPN) transform to myelofibrosis (MF) and highly lethal acute myeloid leukemia (AML), although actionable mechanisms driving progression remain elusive. The HMGA1 chromatin regulator is up-regulated during MPN progression with highest levels after transformation. HMGA1 depletion in JAK2V617F MPN AML cell lines disrupts proliferation, clonogenicity, and leukemic engraftment. Surprisingly, loss of just a single Hmga1 allele prevents progression to MF in JAK2V617F transgenic mice, decreasing blood counts and expansion in stem and myeloid progenitors while preventing splenomegaly and fibrosis within the spleen and bone marrow. RNA sequencing revealed HMGA1-dependent transcriptional networks that govern proliferation (E2F, G2M, mitosis, MYC targets) and cell fate, including the GATA2 master regulatory gene. Silencing GATA2 recapitulates phenotypes observed with HMGA1 depletion whereas GATA2 re-expression partially rescues leukemogenesis. HMGA1 transactivates GATA2 through sequences near the developmental enhancer (+9.5), increasing chromatin accessibility and recruiting active histone marks. Further, HMGA1 transcriptional networks, including GATA2, are activated in human MF after leukemic transformation. Further, HMGA1 depletion synergizes with the JAK2 inhibitor, ruxolitinib, to prolong survival in murine MPN AML. These findings illuminate HMGA1 as a key epigenetic switch required for MPN transformation and promising therapeutic target to treat or prevent disease progression.
Project description:A group of colorectal cancer (CRC) patients treated with chemotherapy and Bevacizumab (Bev) maintain the same sensitivity after progression to maintenance treatment because they remain dependent on VEGF angiogenic mediator, while other patients in whom there is an angiogenic switch (AS) become dependent on other angiogenic cytokines and become resistant to Bev chemotherapy combinations .
Project description:We used expression profiling, SNP arrays, and mutational profiling to investigate a well-characterized cohort of MPN patients. MPN patients with homozygous JAK2V617F mutations were characterized by a distinctive transcriptional profile. Notably, a transcriptional signature consistent with activated JAK2 signaling is seen in all MPN patients regardless of clinical phenotype or mutational status. In addition, the activated JAK2 signature was present in patients with somatic CALR mutations. Conversely, we identified a gene expression signature of CALR mutations; this signature was significantly enriched in JAK2-mutant MPN patients consistent with a shared mechanism of transformation by JAK2 and CALR mutations. We also identified a transcriptional signature of TET2 mutations in MPN patent samples. Our data indicate that MPN patients, regardless of diagnosis or JAK mutational status are characterized by a distinct gene expression signature with upregulation of JAK-STAT target genes, demonstrating the central importance of the JAK-STAT pathway in MPN pathogenesis. [MPN patients] We have performed microarray gene expression analysis in 93 patients with MPNs (28 PV, 47 ET, 18 MF) and 11 age-matched normal donors.
Project description:Philadelphia-chromosome negative myeloproliferative neoplasms (MPNs) including polycythemia vera, essential thrombocythemia and primary myelofibrosis show an inherent tendency for transformation into leukemia (MPN-blast phase), which is hypothesized to be accompanied by acquisition of additional genomic lesions. We, therefore, examined chromosomal abnormalities by high-resolution single-nucleotide polymorphism (SNP) array in 88 MPN patients, as well as 71 cases with MPN-blast phase, and correlated these findings with their clinical parameters. Frequent genomic alterations were found in MPN after leukemic transformation with up to 3-fold more genomic changes per sample compared to samples in chronic phase (p<0.001). We identified commonly altered regions involved in disease progression including established targets (ETV6, TP53 and RUNX1), as well as new candidate genes on 7q, 16q, 19p and 21q. Moreover, trisomy 8 or amplification of 8q24 (MYC) was almost exclusively detected in JAK2V617F(-) cases with MPN-blast phase. Remarkably, copy-number neutral-loss of heterozygosity (CNN-LOH) on either 7q or 9p including homozygous JAK2V617F was related to decreased survival after leukemic transformation (p=0.01 and p=0.016, respectively). Our high density SNP-array analysis of MPN genomes in the chronic compared to leukemic stage identified novel target genes and provided prognostic insights associated with the evolution to leukemia. Keywords: SNP-chip To identify oncogenic lesions in MPD, we performed a genome-wide analysis of primary MPD samples using high-density SNP arrays (Affymetrix GeneChip).
Project description:Apoptosis Repressor with Caspase Recruitment Domain (ARC) was recently found to be highly expressed in solid tumors and in blast cells of patients with acute myeloid leukemia (AML). In this study, we assessed the functional and molecular consequences of loss of ARC on the hematopoietic system. We found, unexpectedly, that deletion of Nol3 (the gene that encodes ARC) in mice leads to development of a myeloproliferative neoplasm (MPN) resembling primary myelofibrosis (PMF). Nol3-/--induced MPN is transplantable into secondary recipient mice and is characterized by anemia, thrombocytopenia, extramedullary hematopoiesis, and bone marrow fibrosis. Despite an overall reduction in bone marrow cellularity Nol3-/- MPN mice have an expanded Thy1+LSK stem cell population with increased cell cycling, in addition to a myelomonocytic differentiation bias. Molecularly, the Nol3-/--induced phenotype is, at least in part, mediated by activation of cyclin-dependent kinases 4 (CDK4) and 6 (CDK6) and MYC. Nol3-/- MPN Thy1+LSK cells show significant molecular similarities with primary CD34+ cells isolated from patients with PMF. Furthermore, we found that Nol3 is deleted in patients with human myeloid malignancies and has decreased expression in a subset of patients with de novo AML. Our results reveal a novel role of Nol3 in normal hematopoiesis and in the pathogenesis of myeloid malignancies. To obtain insight into the molecular mechanism of the Nol3-/- -induced MPN, we performed gene expression profiling on Thy1+LSK bone marrow cells from Nol3+/+ and Nol3-/- MPN mice
Project description:Genomic DNA of granulocytes or mononuclear cell fractions of 408 myeloproliferative neoplasm (MPN) patients was analyzed using Affymetrix Genome-Wide Human SNP 6.0 arrays