Project description:Transcription profiling by array of human cytogenetically normal acute myeloid leukemia patient samples with and without Wilms tumor 1 gene mutations
Project description:The caudal-related homeobox transcription factor CDX2 is ectopically expressed in the majority of patients with acute myeloid leukemia (AML). We generated an inducible transgenic mouse model whereby Cdx2 was specifically activated in HSCs . Cdx2 mice developed myelodysplastic syndrome (MDS) with progression to acute leukemia associated with stepwise acquisition of additional driver mutations.
Project description:The caudal-related homeobox transcription factor CDX2 is ectopically expressed in the majority of patients with acute myeloid leukemia (AML). We generated an inducible transgenic mouse model whereby Cdx2 was specifically activated in HSCs . Cdx2 mice developed myelodysplastic syndrome (MDS) with progression to acute leukemia associated with stepwise acquisition of additional driver mutations.
Project description:The caudal-related homeobox transcription factor CDX2 is ectopically expressed in the majority of patients with acute myeloid leukemia (AML). We generated an inducible transgenic mouse model whereby Cdx2 was specifically activated in HSCs. Cdx2 mice developed myelodysplastic syndrome (MDS) with progression to acute leukemia associated with stepwise acquisition of additional driver mutations.
Project description:The caudal-related homeobox transcription factor CDX2 is ectopically expressed in the majority of patients with acute myeloid leukemia (AML). We generated an inducible transgenic mouse model whereby Cdx2 was specifically activated in HSCs. Cdx2 mice developed myelodysplastic syndrome (MDS) with progression to acute leukemia associated with stepwise acquisition of additional driver mutations.
Project description:Acute Myeloid Leukemia (AML) is a heterogeneous disease from the molecular and biological standpoints, and even patients with a specific gene expression profile may present clinical and molecular heterogeneity. We studied the epigenetic profiles of a cohort of patients that shared a common gene expression profile but differed in that only half of them harbored mutations of the CEBPA locus, while the rest presented with silencing of this gene and co-expression of certain T cell markers. DNA methylation studies revealed that these two groups of patients could be readily segregated in an unsupervised fashion based on their DNA methylation profiles alone. Furthermore, CEBPA silencing was associated with the presence of an aberrant DNA hypermethylation signature, which was not present in the CEBPA mutant group. This aberrant hypermethylation occurred more frequently at sites within CpG islands. CEBPA silenced leukemias also displayed marked hypermethylation when compared with normal CD34+ hematopoietic cells, while CEBPA mutant cases showed only mild changes in DNA methylation when compared to these normal progenitors. Biologically, CEBPA silenced leukemias presented with a decreased response to myeloid growth factors in vitro. Experiment Overall Design: Direct comparison of gene expression in leukemic blasts from 8 patients with Acute Myeloid Leukemia (AML) carrying a CEBPA mutation and 8 patients with AML without CEBPA mutation but with silencing of CEBPA expression, and with 9 samples of T Acute Lymphoblastic Leukemia (T-ALL) patients.
Project description:The pretreatment karyotype of leukemic blasts is currently the key determinant in therapy decision-making in acute myeloid leukemia (AML). However, approximately fifty percent of AML patients, often carrying a normal karyotype, are currently unclassifiable based these established methods. Gene expression profiling has proven to be valuable for risk stratification of AML. The gene expression profiles of AML samples of two independent cohorts (n=247 and n=214) were determined using Affymetrix U133Plus2.0 GeneChips: all Samples (starting with 'amlrrays 2') below 4000 are in the training cohort; all Samples higher than 4000 are in the validation cohort. Data analyses were carried out to discover and predict prognostically relevant subtypes in AML (<60 years) based on their gene expression signatures. Statistical analyses were performed to determine the prognostic significance of cases of AML with specific molecular signatures. Unsupervised cluster analyses of the gene expression signatures of both independent cohorts of AML patients confirmed that chromosomal lesions and mutations, often resulting in aberrant transcription factors, induce discriminatory patterns of gene expression. In contrast, however, mutations in signalling molecules do not establish strong molecular signatures. Consequently, prognostically important subtypes, which express mutated trancription factors were predicted with high accuracy using minimal sets of genes. We identified several novel clusters, some consisting of patients with normal karyotypes. Gene expression profiling allows classification of AML subtypes characterized by the expression of abnormal transcription factors, however, prediction of clinically relevant mutations affecting signalling molecules is impossible and thus still requires addition molecular methods. Experiment Overall Design: 461 blood or bone marrow samples of acute myeloid leukemia patients were hybridized to Affymetrix HG-U133 plus 2 GeneChips.
Project description:Acute Myeloid Leukemia (AML) is a heterogeneous disease from the molecular and biological standpoints, and even patients with a specific gene expression profile may present clinical and molecular heterogeneity. We studied the epigenetic profiles of a cohort of patients that shared a common gene expression profile but differed in that only half of them harbored mutations of the CEBPA locus, while the rest presented with silencing of this gene and co-expression of certain T cell markers. DNA methylation studies revealed that these two groups of patients could be readily segregated in an unsupervised fashion based on their DNA methylation profiles alone. Furthermore, CEBPA silencing was associated with the presence of an aberrant DNA hypermethylation signature, which was not present in the CEBPA mutant group. This aberrant hypermethylation occurred more frequently at sites within CpG islands. CEBPA silenced leukemias also displayed marked hypermethylation when compared with normal CD34+ hematopoietic cells, while CEBPA mutant cases showed only mild changes in DNA methylation when compared to these normal progenitors. Biologically, CEBPA silenced leukemias presented with a decreased response to myeloid growth factors in vitro. Keywords: DNA methylation profiling Direct comparison of DNA methylation in leukemic blasts from 8 patients with Acute Myeloid Leukemia (AML) carrying a CEBPA mutation and 8 patients with AML without CEBPA mutation but with silencing of CEBPA expression. Two control groups are included: 8 CD34+ bone marrow samples from healthy donors and 9 samples of T Acute Lymphoblastic Leukemia (T-ALL) patients.
Project description:Leukemia initiating cells (LICs) of acute myeloid leukemia (AML) may arise from self-renewing hematopoietic stem cells (HSCs) and from committed progenitors. However, it remains unclear how leukemia-associated oncogenes instruct LIC formation from cells of different origins and if differentiation along the normal hematopoietic hierarchy is involved. Here, using murine models with the driver mutations MLL-AF9 or MOZ-TIF2, we found that regardless of the transformed cell types, myelomonocytic differentiation to the granulocyte macrophage progenitor (GMP) stage is critical for LIC generation. Blocking myeloid differentiation through disrupting the lineage-restricted transcription factor C/EBPa eliminates GMPs, blocks normal granulopoiesis, and prevents AML development. In contrast, restoring myeloid differentiation through inflammatory cytokines “rescues” AML transformation. Our findings identify myeloid differentiation as a critical step in LIC formation and AML development, thus guiding new therapeutic approaches. Examination of chromatin accessibility in Cebpa knock-out and control conditions.
Project description:Myelodysplastic syndromes (MDS) are a heterogenous group of hematopoietic stem cell disorders characterized by dysplastic blood cell formation and peripheral blood cytopenias. Up to 30% of patients with MDS will progress to a highly chemotherapy-resistant secondary acute myeloid leukemia (sAML). We identified mutations in U2AF1 in MDS patients and patients with U2AF1 mutations are at an increased risk of developing sAML. We identified mutations in U2AF1 in patients with MDS and hypothesized that U2AF1 mutations may represent a novel mechanism that could alter gene expression in MDS. To elucidate gene expression changes associated with U2AF1 mutations, we analyzed the global mRNA expression profile obtained from bone marrow CD34+ cells purified from 5 MDS patients with a U2AF1 mutation, 10 MDS patients without a mutation, and 4 normal donors.