Project description:In our previous study, the roles of zinc finger protein X-linked (ZFX) in CML cells were revealed. We showed that ZFX expression was significantly higher in CML CD34+ cells than in control cells. Overexpression and gene silencing experiments indicated that ZFX promoted the in vitro growth of CML cells, conferred imatinib mesylate (IM) resistance to these cells, and enhanced BCR/ABL-induced malignant transformation. To obtain molecular insights of how ZFX modulates the growth and imatinib response of CML stem and progenitor cells, we generated microarray data comparing ZFX silenced CML CD34+ cells with control (Scramble) cells.
Project description:In our previous study, the roles of heterogeneous nuclear ribonucleoprotein D-like (HNRPDL) in CML cells were revealed. We found that overexpression of HNRPDL transformed murine BaF3 cells and induced lethal mice leukemia. Conversely, HNRPDL silencing inhibited colony-forming cell (CFC) production of CML CD34+ cells and attenuated BCR-ABL induced mice leukemia. In addition, HNRPDL modulated imatinib response of K562 cells and HNRPDL silencing sensitized CML CD34+ cells to imatinib treatment. To obtain molecular insights of how HNRPDL modulates the growth and imatinib response of human CML cells, we generated microarray data comparing HNRPDL silenced K562 cells with control (Scramble) cells.
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: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: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.
Project description:Imatinib therapy is first-line treatment for chronic myeloid leukemia (CML), and its failure to target CML progenitor/stem cells may lead to an increased risk of relapse. We report here that fenretinide, a well-tolerated vitamin A derivative, is capable of eradicating primitive CML progenitor/stem cells and significantly enhances the efficacy of imatinib at physiologically achievable concentrations. As tested by colony forming cell assays, formation of various colonies derived primitive CML CD34+ cells was significantly suppressed by fenretinide, particularly with respect to the formation of colonies derived from erythroid progenitors and more primitive CML progenitor/stem cells. Also, fenretinide significantly enhanced the ability of imatinib to suppress the formation of the colonies. Moreover, fenretinide was able to induce apoptosis in primitive CML CD34+ cells while sparing the normal counterparts. In particular, primitive CML CD34+CD38- cells appeared to be most sensitive to fenretinide induced apoptosis. Through transcriptome analysis and molecular validation, we further showed that fenretinide induced apoptosis in CML CD34+ cells was probably mediated by a series of stress responsive events which were likely triggered by elevated levels of intracellular reactive oxygen species. Accordingly, the combination of fenretinide and imatinib may provide a potential solution for overcoming relapse and resistance in CML. Experiment Overall Design: Transcriptome profiles of CML CD34+ cells with and without fenretinide treatment were analyzed using whole genome expression arrays (Affymetrix HG-U133 Plus 2.0) in four CML patients (CML32, CML33, CML34 and CML35, see Table 1). To minimize potential data biases, both treated and untreated cell samples were maintained in culture for 48 hours before hybridization.
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:Chronic myelogenous leukaemia (CML) is a malignant disorder of the hematopoietic stem cell, which is characterized by the reciprocal translocation between chromosomes 9 and 22 (t(9;22)(q34;q11)) The translocation results in the formation of the BCR-ABL fusion oncogene encoding a protein with constitutive activated tyrosine kinase activity which plays a central role in the pathogenesis of the disease. There are still several open questions with respect to BCR-ABL-induced malignant transformation. A large limitation of the existing data about BCR-ABL effects is that they are derived to a great proportion from human hematopoietic cell lines, BCR-ABL-transformed murine cell lines or fibroblasts and mouse models, which might not be representative for chronic phase CML. A suitable cell population for studies on CML biology are primary hematopoietic stem and progenitor cells from patients with CML. Therefore, we provide in this study a genome-wide expression signature of highly enriched CD34+ cells from bone marrow (BM) of untreated patients with CML in chronic phase. Gene expression profiles of immunomagnetically enriched BM CML CD34+ cells (n=9) were compared with those of normal BM CD34+ cells (n=8) using microarrays covering 8.746 genes. Total RNA was extracted, reversely transcribed, in vitro transcribed and labelled and hybridized to Affymetrix HG Focus Arrays. Following quality control and normalization differentially expressed genes were identified by significance analysis of microarrays (SAM). Comparing both groups 918 genes were significantly differentially expressed (q value <0.1%; fold change > 1.3). Several of the BCR-ABL-induced effects described in cell lines and BCR-ABL-transduced cells could also be found in primary CML progenitor cells as for example the transcriptional activation of the classical MAPK pathway and the PI3 kinase/AKT pathway and the down-regulation of the pro-apoptotic gene IRF8. Moreover, novel transcriptional changes in comparison with normal CD34+ cells were identified. These include an up-regulation of components of the TGFb signalling pathway and the non-canonical Wnt/Ca2+ pathway, a transcriptional activation of fetal haemoglobin genes and genes associated with early hematopoietic stem cells (HSC) such as HoxA9 and MEIS1 and up-regulation of genes involved in fatty acid metabolism, of the thrombin receptor PAR1 and the neuroepithelial cell transforming gene 1. Differential expression of differentiation-associated genes suggested an alteration of the composition of the CD34+ cell population in CML. This was confirmed by immunophenotypical subset analyses of chronic phase CML CD34+ cells showing an increase of erythroid progenitors and a decrease of granulocyte-macrophage progenitor cells while the proportion of HSC was similar in normal and CML CD34+ cells. In conclusion, our results give novel insights into the biology of CML hematopoietic stem and progenitor cells and could be the basis for identification of new targets for therapy. Keywords: ordered