Project description:A characteristic of chronic phase CML is accumulation of mature cells in the peripheral blood. It has not been determined if this expansion is explained by the CD34+ cell subset composition. We conducted flowcytometry-based cell sorting to assess the CD34+ subset composition and to retrieve the respective cells. We found a significant increase in the proportion of MEP and a decrease of HSC and GMP in patients with chronic phase CML compared to their healthy counterparts. The absolute number of HSC was similar, whereas CMP, GMP and MEP were expanded 2.8- to 7.7-fold. Gene expression analysis of CD34+ cell subsets showed, that in contrast to the normal developmental hierachy, CML HSC have a transcriptional profile which is similar to CML progenitor subsets and healthy CMP. HSC in healthy individuals show greater distance to their more mature progeny within the developmental hierarchy. As the differences between CML and healthy controls were minor at the progenitor level, we focused on the further characterization of CML HSC. 614 genes were differentially expressed, including downregulation of genes involved in adhesion and migration, regulation of the stem cell pool, and differentiation. We also found abrogation of nuclear receptors NR4A1 and NR4A3, and decreased expression of c-Jun and JunB. Re-expression of c-Jun and JunB in CD34+ cells from CML patients was achieved by co-transfection of NR4A1 and NR4A3. Moreover, we functionally corroborated a decreased adhesion capacity of the CML HSC. Taken together, these findings help to explain the hematological phenotype of CML patients in chronic phase. Experiment Overall Design: CD34+ subsets of 6 patients with chronic phase CML and 5 healthy volunteers were analysed by means of gene expression profiling with the Affymetrix HU-133A 2.0 array
Project description:We analysed genome wide DNA methylation of mature (CD34-CD15+) and immature (CD34+CD15-) hematopoietic cells from patients with chronic phase CML at diagnosis. before any treatment. and compared it to their counterpart cells isolated from healthy donors.
Project description:LMPPs comprise of heterogeneous populations which are progenitors of lymphocytes and myeloid cells. We aim to identify the difference of distribution of the diverse populations from CP-CML versus BC-CML patients.
Project description:We found that composition of cell subsets within the CD34+ cell population is markedly altered in chronic phase (CP) chronic myeloid leukemia (CML). Specifically, proportions and absolute cell counts of common myeloid progenitors (CMP) and megakaryocyte-erythrocyte progenitors (MEP) are significantly greater in comparison to normal bone marrow whereas absolute numbers of hematopoietic stem cells (HSC) are equal. To understand the basis for this, we performed gene expression profiling (Affymetrix HU-133A 2.0) of the distinct CD34+ cell subsets from six patients with CP CML and five healthy donors. Euclidean distance analysis revealed a remarkable transcriptional similarity between the CML patients' HSC and normal progenitors, especially CMP. CP CML HSC were transcriptionally more similar to their progeny than normal HSC to theirs, suggesting a more mature phenotype. Hence, the greatest differences between CP CML patients and normal donors were apparent in HSC including downregulation of genes encoding adhesion molecules, transcription factors, regulators of stem-cell fate and inhibitors of cell proliferation in CP CML. Impaired adhesive and migratory capacities were functionally corroborated by fibronectin detachment analysis and transwell assays, respectively. Based on our findings we propose a loss of quiescence of the CML HSC on detachment from the niche leading to expansion of myeloid progenitors.
Project description:This study compares the epigenetic signatures of CD34+ cells from chronic phase chronic myeloid leukemia (CML) samples and blast phase CML samples v.s. normal CD34+ cells from cord blood and adult bone marrow samples. H3K27me3 genomic loci were detected by ChIP-seq.
Project description:Analysis of lin-CD34+CD45+ (iCD34+) cell population from two normal bone marrow-derived (BM1K and BM9) iPSCs and two CML (CML15 and CML17) iPSCs . CML iCD34+ cells have characteristics similar to primary CML leukemia stem cell in patients. Results provide insight into molecular profile characterized CML iCD34 and mechanism of its maintenance and drug resistance. iCD34+ cell samples obtained from two control BM1K and BM9 iPSCs (both for the same normal donor) and CML15 and CML17 iPSCs (both from the same patient in chronic phase of CML). Each group was treated with DMSO (control) or 5 μM imatinib. The complete phenotype for iCD34+ cells: lin-CD34+CD45+CD90+CD117+CD45RA-. This population also inclyde Rhodaminelow and ALDKhigh cells.
Project description:Imatinib, as the first-line agent of chronic myeloid leukemia (CML), is ineffective in eradicating CML stem/progenitor cells, thus unable to prevent late relapse. Here we present data indicating that fenretinide preferentially targets CD34+ CML cells and enhances the efficacy of imatinib in CML. As tested by colony forming cell assays, both number and size of total colonies derived from CD34+ CML cells were significantly reduced by fenretinide, and by combining fenretinide with imatinib. In particular, colonies derived from erythroid progenitors and those derived from more primitive pluripotent progenitor cells were highly sensitive to fenretinide/fenretinide plus immtinib. Further data showed that fenretinide was able to induce apoptosis in CD34+ CML cells which were refractory to imatinib. Through transcriptome analysis and followed by molecular validation, we further showed that apoptosis induced by fenretinide in CD34+ CML cells was mediated by complex mechanisms of stress responses, probably triggered by elevated levels of intracellular reactive oxygen species. Thus, fenretinide combines with imatinib may represent a new strategy for the treatment of CML, in which fenretinide targets primitive CD34+ CML cells whereas imatinib targets leukemic blasts. This strategy may eventually reduce the risk of relapse and probably resistant as well in CML patients.
Project description:BACKGROUND: BCR-ABL1+ chronic myeloid leukemia (CML) is characterized by abnormal production of leukemic stem (LSC) and progenitor cells and their spread from the bone marrow into the blood resulting in extramedullary myeloproliferation. So far, little is known about specific markers and functions of LSC in CML. METHODS: We examined the phenotype and function of CD34+/CD38─/Lin─ CML LSC by a multi-parameter screen approach employing antibody-phenotyping, mRNA expression profiling, and functional studies, including LSC repopulation experiments in irradiated NOD-SCID-IL-2Rgamma-/- (NSG) mice, followed by marker-validation using diverse control-cohorts and follow-up samples of CML patients treated with imatinib. RESULTS: Of all LSC markers examined, dipeptidylpeptidase IV (DPPIV=CD26) was identified as specific and functionally relevant surface marker-enzyme on CD34+/CD38─ CML LSC. CD26 was not detected on normal CD34+/CD38─ stem cells or LSC in other hematopoietic malignancies. The percentage of CD26+ CML LSC decreased to undetectable levels during successful treatment with imatinib in all patients (p<0.001). Whereas the sorted CD26─ stem cells obtained from CML patients engrafted irradiated NSG mice with multilineage BCR-ABL1-negative hematopoiesis, CD26+ LSC engrafted NSG mice with BCR-ABL1+ cells. Functionally, CD26 was identified as target-enzyme disrupting the SDF-1alpha-CXCR4-axis by cleaving SDF-1alpha a chemotaxin for CXCR4+ stem cells. Whereas CD26 was found to inhibit SDF-1alpha-induced migration, CD26-targeting gliptins reverted this effect and blocked the mobilization of CML LSC in a stroma co-culture assay. CONCLUSIONS: CD26 is a robust biomarker of LSC and a useful tool for their quantification and isolation in patients with BCR/ABL1+ CML. Moreover, CD26 expression may explain the extramedullary spread of LSC in CML. To define specific mRNA expression patterns and to identify specific LSC markers in CML LSC, gene array analyses were performed. RNA was isolated from sorted CD34+/CD45+/CD38─ CML LSC, CD34+/CD45+/CD38+ CML progenitor cells, CML MNC, sorted CD34+/CD38─ cord blood (CB) SC, CB-derived CD34+/CD38+ progenitor cells, and CB MNC. Total RNA was extracted from sorted cells using RNeasy Micro-Kit (Qiagen) and used (100 ng total RNA) for Gene Chip analyses. Preparation of terminal-labeled cRNA, hybridization to genome-wide human PrimeView GeneChips (Affymetrix, Santa Clara, CA, USA) and scanning of arrays were carried out according to the manufacturer's protocols (https://www.affymetrix.com). Robust Multichip Average (RMA) signal extraction and normalization were performed according to http://www.bioconductor.org/ as described.18 Differences in mRNA expression levels (from multiple paired samples) were calculated as mRNA ratio of i) CML LSC versus CB SC, ii) CML LSC versus CD34+/CD38+ CML progenitors, and normal cord blood SC versus cord blood progenitors. To calculate differential gene expression between individual sample groups where appropriate, we performed a statistical comparison using the LIMMA package as described previously. Briefly, LIMMA estimates the fold change between predefined sample groups by fitting a linear model and using an empirical Bayes method to moderate the standard errors of the estimated log-fold changes for each probe set.
Project description:In an attempt to identify novel markers and immunologic targets in leukemic stem cells (LSC) in acute myeloid leukemia (AML) and chronic myeloid leukemia (CML), we screened samples of patients with AML, CML, and controls for expression of cell surface antigens on CD34+/CD38− and CD34+/CD38+ cells by multi-color flow cytometry. In addition, we examined mRNA expression profiles in highly purified CD34+/CD38− and CD34+/CD38+ cells by gene array- and qPCR analyses. Aberrantly expressed markers were identified in all patient cohorts examined.