CD52 Expression In Leukemic Stem/Progenitor Cells

Abstract Abstract 2743 CD52 is a cell surface glycoprotein of unknown function that is expressed in B and T lymphocytes, macrophages, and monocytes, but is not expressed in normal hematopoietic stem/progenitor cells. CD52 is also expressed in chronic lymphocytic leukemia (CLL), B-cell acute lymphoblastic leukemia (ALL), and some cases of T-ALL. Alemtuzumab, a recombinant humanized monoclonal antibody, targets CD52 and is used to treat CLL. In contrast to normal hematopoietic stem/progenitor cells, CD52 expression has been described in acute myeloid leukemia (AML) and in blast crisis (BC) chronic myeloid leukemia (CML). Based on these observations we were curious whether CD52 expression distinguished normal from malignant or more mature from immature stem/progenitors cells, and whether these cells were sensitive to alemtuzumab. CD52 expression was examined in three blast cell populations (CD34+/CD38-, CD34+/CD38+, and CD34-) in patients with myeloid (44) and lymphoid (18) neoplasms, and normal patients (6). In normal hematopoietic cells, stems cells are enriched in the first population; more mature cells are characterized by increasing CD38 expression and loss of CD34 expression. In AML and CML leukemia stem cells may arise within either CD34+ population and possibly in the CD34- population. Relative to normal lymphocytes average CD52 expression could be characterized as low to moderate. Using an expression cutoff of > 20%, in contrast to normal patients, CD52 was detected in at least one of three blast populations in almost all patients. Using a more stringent cutoff of > 50%, CD52 was expressed in CD34+/CD38- cells in 7/11 B-ALL and 6/7 T-ALL cases and was concordantly expressed in the other two populations. Using the same criteria in myeloid malignancies (Table 1), expression occurred more frequently in AML, AML arising from myelodysplastic syndrome (MDS), and BC CML. In AML and AML arising from MDS, CD52 was expressed in the 34+/38- population in 7/15 cases (47%) and 4/7 cases (57%), respectively; it was expressed in both BC CML patients. In AML and BC CML patients, CD52 was expressed at similar levels in the CD34+/CD38+ fraction. No clear association between CD52 expression and cytogenetic abnormalities was found. We then examined whether CD52 expression differentiated normal from malignant blasts (CD34+/CD38- and CD34+/CD38+) in two CML myeloid BC patients. FISH and quantitative PCR demonstrated that BCR-ABL was expressed in all 4 populations, which were also morphologically distinct. Colony forming unit (CFU) assays demonstrated a significantly decreased ability to form CFU (on average 5–20 fold decrease) in CD52+/CD34+/CD38- CML cells suggesting CD52 cells may be more mature. Lastly and not previously described, we found that several BC CML cell lines express CD52, and complement-mediated cell cytotoxicity was similar in the highest expressing cell lines to that seen in EHEB (B-CLL) cells known to be targeted by alemtuzumab. Thus, alemtuzumab may have clinical efficacy in BC CML. In conclusion, CD52 is expressed on blast populations enriched for leukemic stem cells. Whether the absence or presence of CD52 more precisely segregates a leukemia stem cell containing population currently remains unknown and requires functional testing in a murine model. Our preliminary experiments in CML suggest CD52 may not differentiate between normal and malignant stem/progenitor cells. However, CD52 expression may distinguish normal and malignant stem cell populations in cases where CD52 and CD38 are more highly expressed. The observation that CD52 expression is increased in acute vs. chronic leukemias raises the intriguing possibility that CD52, if not directly involved, may be a marker for genes or pathways contributing to the block in differentiation seen with progression to acute leukemia. Furthermore, given that CD52 expression is heterogeneous in chronic disorders, it is possible that CD52 expression within these populations may correlate with poor prognosis or impending leukemic conversion. Table 1. The proportion of patients (44) expressing CD52 at levels > 50% in 3 blast populations. Three populations were present in most, but not all patients. Gray shading indicates chronic myeloid diseases. MPN is myeloproliferative neoplasm; NOS is not otherwise specified; ET is essential thrombocythemia; CMML is chronic myelomonocytic leukemia; and an arrow represents progressed to. Disclosure: Oehler: Pfizer: Research Funding. Radich:Novartis: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria.

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Very Small Embryonic-Like Stem Cells, Endothelial Progenitor Cells, and Different Monocyte Subsets Are Effectively Mobilized in Acute Lymphoblastic Leukemia Patients after G-CSF Treatment

Stem Cells International ◽

10.1155/2018/1943980 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8 ◽

Cited By ~ 4

Author(s):

Andrzej Eljaszewicz ◽

Lukasz Bolkun ◽

Kamil Grubczak ◽

Malgorzata Rusak ◽

Tomasz Wasiluk ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Acute Lymphoblastic Leukemia ◽

Progenitor Cells ◽

Endothelial Progenitor Cells ◽

Lymphoblastic Leukemia ◽

Monocyte Subsets ◽

Endothelial Progenitor ◽

Hematopoietic Stem ◽

Cd34 Cells

Background. Acute lymphoblastic leukemia (ALL) is a malignant disease of lymphoid progenitor cells. ALL chemotherapy is associated with numerous side effects including neutropenia that is routinely prevented by the administration of growth factors such as granulocyte colony-stimulating factor (G-CSF). To date, the effects of G-CSF treatment on the level of mobilization of different stem and progenitor cells in ALL patients subjected to clinically effective chemotherapy have not been fully elucidated. Therefore, in this study we aimed to assess the effect of administration of G-CSF to ALL patients on mobilization of other than hematopoietic stem cell (HSCs) subsets, namely, very small embryonic-like stem cells (VSELs), endothelial progenitor cells (EPCs), and different monocyte subsets. Methods. We used multicolor flow cytometry to quantitate numbers of CD34+ cells, hematopoietic stem cells (HSCs), VSELs, EPCs, and different monocyte subsets in the peripheral blood of ALL patients and normal age-matched blood donors. Results. We showed that ALL patients following chemotherapy, when compared to healthy donors, presented with significantly lower numbers of CD34+ cells, HSCs, VSELs, and CD14+ monocytes, but not EPCs. Moreover, we found that G-CSF administration induced effective mobilization of all the abovementioned progenitor and stem cell subsets with high regenerative and proangiogenic potential. Conclusion. These findings contribute to better understanding the beneficial clinical effect of G-CSF administration in ALL patients following successful chemotherapy.

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Aldehyde Dehydrogenase Expression in Primitive Human Hematopoietic Progenitor Cells with Side Population Characteristic and in Samples from Patients with Acute Myeloid Leukemia.

Blood ◽

10.1182/blood.v106.11.4570.4570 ◽

2005 ◽

Vol 106 (11) ◽

pp. 4570-4570

Author(s):

Ute Meissauer ◽

Joerg Hoffmann ◽

Christian Scharenberg ◽

Andreas Neubauer ◽

Cornelia Brendel

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Progenitor Cells ◽

Myeloid Leukemia ◽

Staining Pattern ◽

Side Population ◽

Aldh Activity ◽

Hematopoietic Progenitor ◽

Hematopoietic Stem ◽

Blast Cells

Abstract High activity of the detoxifying enzyme aldehyde dehydrogenase (ALDH) has been attributed to primitive hematopoietic stem cells in the murine and human system. ALDH activity can be measured by a functional assay employing BODIPY-aminoacetaldehyde (BAAA) as a fluorescent intracellular substrate. High ALDH activity within hematopoietic stem cells is associated with CD34 and AC133 surface expression. Given the co-expression of these markers in acute myeloid leukemia (AML), we sought to investigate whether ALDH-activity can be detected in early blood stem cell disorders and in primitive hematopoietic progenitor cells with the side population phenotype. Employing a commercial Aldefluor™ -kit thirteen peripheral blood and bone marrow samples from patients with AML were stained for ALDH activity. Four samples exhibited a clearly distinctive positive staining pattern when compared to the inhibitor control, i.e. 16–91% of AML blast cells were considered as ALDH positive. The staining pattern was similar to marrow samples from healthy donors or peripheral blood sample controls from G-CSF-mobilised healthy stem cell donors. In addition we investigated ALDH activity in primitive bone marrow side population (SP) cells from healthy individuals. Although the ALDH substrate BAAA is actively extruded out of cells and especially SP stem cells by an ABC-transporter-activity, we established a co-staining method for Hoechst 33342 and BAAA by inclusion of specific ABC-transporter inhibitors. Both SP cells and ALDH-positive cells appeared as a clear distinctive population with some overlap between both populations. Quantitative RT-PCR of different sorted stem cell samples confirmed that SP cells had higher ABCG2-expression than ALDH positive cells and ABCG2-expression was higher in ALDH positive cells compared to the total cell fraction or granulocytes. We conclude that ALDH is expressed in some but not all AML blast cells. This is in accordance with the cytogenetic heterogeneity of this disease and may have therapeutic implications because of the detoxifying activity of the ALDH enzyme. In addition ALDH activity can also be found on a minor population of very primitive marrow progenitor cells. Whether high ALDH activity is a feature of the leukemic stem cell requires further investigation.

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CGRP Signaling via CALCRL Increases Chemotherapy Resistance and Stem Cell Properties in Acute Myeloid Leukemia

International Journal of Molecular Sciences ◽

10.3390/ijms20235826 ◽

2019 ◽

Vol 20 (23) ◽

pp. 5826 ◽

Cited By ~ 2

Author(s):

Tobias Gluexam ◽

Alexander M. Grandits ◽

Angela Schlerka ◽

Chi Huu Nguyen ◽

Julia Etzler ◽

...

Keyword(s):

Stem Cells ◽

Acute Myeloid Leukemia ◽

Stem Cell ◽

Mouse Model ◽

Cell Lines ◽

Myeloid Leukemia ◽

Leukemic Cells ◽

Hematopoietic Stem ◽

Acute Myeloid

The neuropeptide CGRP, acting through the G-protein coupled receptor CALCRL and its coreceptor RAMP1, plays a key role in migraines, which has led to the clinical development of several inhibitory compounds. Recently, high CALCRL expression has been shown to be associated with a poor prognosis in acute myeloid leukemia (AML). We investigate, therefore, the functional role of the CGRP-CALCRL axis in AML. To this end, in silico analyses, human AML cell lines, primary patient samples, and a C57BL/6-based mouse model of AML are used. We find that CALCRL is up-regulated at relapse of AML, in leukemic stem cells (LSCs) versus bulk leukemic cells, and in LSCs versus normal hematopoietic stem cells. CGRP protects receptor-positive AML cell lines and primary AML samples from apoptosis induced by cytostatic drugs used in AML therapy, and this effect is inhibited by specific antagonists. Furthermore, the CGRP antagonist olcegepant increases differentiation and reduces the leukemic burden as well as key stem cell properties in a mouse model of AML. These data provide a basis for further investigations into a possible role of CGRP-CALCRL inhibition in the therapy of AML.

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Mdm2 Maintains Cholesterol Biosynthesis in Hematopoietic Stem/Progenitor Cells Independent of p53

Blood ◽

10.1182/blood-2021-152899 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 1152-1152

Author(s):

Rasoul Pourebrahim ◽

Rafael Heinz Montoya ◽

Edward Ayoub ◽

Joseph D. Khoury ◽

Michael Andreeff

Keyword(s):

Stem Cells ◽

Hematopoietic Stem Cells ◽

Progenitor Cells ◽

Myeloid Leukemia ◽

Research Funding ◽

Cholesterol Biosynthesis ◽

Heterozygous Deletion ◽

Mdm2 Snp309 ◽

Hematopoietic Stem ◽

Acute Myeloid

Abstract Background: The Mdm2 protein is an E3 ubiquitin ligase that directly interacts with p53 protein leading to its degradation. The expression of MDM2 is controlled by p53 activity through an autoregulatory feedback loop. In addition, a single nucleotide polymorphism (SNP) in the MDM2 promoter modulates its expression and is associated with the risk of cancer. Emerging evidence emphasizes the metabolic activities of MDM2 to be essential for the maintenance of cellular homeostasis. We hypothesized that MDM2 maintains the metabolic homeostasis of hematopoietic stem cells (HSCs) and its downregulation in TP53-mutant leukemias leads to metabolic vulnerabilities independent of p53. Investigation of the metabolic role of MDM2 in hematopoietic stem cells can provide valuable insight into the pathology of TP53 mutant leukemias. Methods: To understand the function of Mdm2 in HSCs, we generated a conditional mouse model driven by Vav-Cre to genetically label and trace the fate of HSCs after heterozygous deletion of Mdm2 in early development and adult bone marrow. We utilized fluorescence microscopy, flow cytometry, apoptosis assays and RNA-seq to functionally characterize the fate of HSCs after heterozygous deletion of Mdm2. Using Trp53 floxed allele and a new Trp53 mutant allele that switches from wildtype to Trp53R172H mutant, we deleted and/or mutated Trp53 gene concomitantly in Mdm2 haplo-insufficient HSCs. Additionally, MDM2 copy number as well as MDM2 SNP309 status were determined in 95 samples from p53 mutant AML patients and 24 controls. Results: Heterozygous deletion of Mdm2 in hematopoietic stem cells (Vav-Cre;mTmG;Mdm2 fl/+) resulted in massive apoptosis of emerging hematopoietic progenitor cells in the aorta-gonad-mesonephros (AGM) region at E11.5. Strikingly, hematopoietic cells residing in fetal liver displayed minimal apoptosis evident by a few TUNEL positive cells. Colony forming assays revealed a myeloid biased hematopoiesis in Mdm2 haplo-insufficient HSCs. Vav-Cre;Mdm2 fl/+ mice displayed a marked reduction in Lin -/CD150 +/c-Kit +/Sca-1 + HSCs cells and significant decrease in peripheral blood counts. Deletion of Trp53 in these mice (Vav-Cre;Trp53 fl/fl;Mdm2 fl/+) resulted in marked decrease in CD19+ B lymphocytes cells whereas the population of CD11b+ myeloid cells did not change. The population of Lin neg-c-Kit + hematopoietic stem/progenitor cells isolated from the bone marrow of Vav-Cre;Mdm2 fl/+ mice displayed marked downregulation of cholesterol biosynthesis and mevalonate pathway (-log2 pvalue=20). Strikingly, 85% of genes involved in cholesterol biosynthesis (29 genes) were downregulated in Vav-Cre;Mdm2 fl/+ mice. Homozygous deletion of Trp53 in Vav-Cre;Mdm2 fl/+ mice did not rescue the metabolic alterations driven by Mdm2 haplo-insufficiency. In addition, the gene signature of oxidative phosphorylation(oxphos), was remarkably upregulated in Vav-Cre;Mdm2 fl/+ mice independent of p53. We further demonstrate that Cre-mediated induction of a Trp53R172 mutation in Mdm2 haplo-insufficient mice resulted in malignant transformation of HSCs leading to acute myeloid leukemia (AML). Of note, mice with homozygote Trp53 mutation and/or deletion without Mdm2- haplo-insufficiency developed lymphoma and not leukemia. In human, MDM2 loss of heterozygosity (MDM2 LOH) in AML was always concomitant with TP53 missense mutations (log2 odds ratio>3, p<.001), and not TP53 deletions or truncations whereas in lymphomas, MDM2 LOH and TP53 mutations were mutually exclusive. Conclusion: Using a genetic model, we have shown that Mdm2 haplo-insufficiency in HSCs leads to apoptosis and clonal selection towards myeloid biased hematopoiesis. Mechanistically, Mdm2 haplo-insufficiency resulted in a metabolic switch from cholesterol biosynthesis to oxphos in HSCs. Notably, this metabolic reprograming is not rescued by deletion of Trp53. However, mutation of Trp53 in Mdm2 haplo-insufficient hematopoietic stem cells resulted in leukemic transformation of HSCs leading to acute myeloid leukemia. Lastly, we demonstrate that MDM2 SNP309 is associated with TP53 mutation in AML and provide clinical evidence that MDM2 loss of heterozygosity is concomitant with TP53 mutations in AML with lower survival compared to TP53 mutant patients with diploid MDM2. Our findings demonstrate a p53-independent role for Mdm2 in metabolic maintenance of hematopoietic stem/progenitor cells. Figure 1 Figure 1. Disclosures Khoury: Kiromic: Research Funding; Angle: Research Funding; Stemline Therapeutics: Research Funding. Andreeff: Glycomimetics: Consultancy; Medicxi: Consultancy; Karyopharm: Research Funding; ONO Pharmaceuticals: Research Funding; Senti-Bio: Consultancy; Reata, Aptose, Eutropics, SentiBio; Chimerix, Oncolyze: Current holder of individual stocks in a privately-held company; Syndax: Consultancy; Amgen: Research Funding; Daiichi-Sankyo: Consultancy, Research Funding; Breast Cancer Research Foundation: Research Funding; Novartis, Cancer UK; Leukemia & Lymphoma Society (LLS), German Research Council; NCI-RDCRN (Rare Disease Clin Network), CLL Foundation; Novartis: Membership on an entity's Board of Directors or advisory committees; Oxford Biomedica UK: Research Funding; AstraZeneca: Research Funding; Aptose: Consultancy.

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Leukemogenic Function of TIM-3, a Leukemia Stem Cell Marker, in Acute Myelogenous Leukemia and Myelodysplastic Syndromes.

Blood ◽

10.1182/blood.v120.21.2983.2983 ◽

2012 ◽

Vol 120 (21) ◽

pp. 2983-2983 ◽

Cited By ~ 2

Author(s):

Yoshikane Kikushige ◽

Takahiro Shima ◽

Junichiro Yuda ◽

Toshihiro Miyamoto ◽

Koichi Akashi

Keyword(s):

Signal Transduction ◽

Stem Cells ◽

Stem Cell ◽

Myelodysplastic Syndromes ◽

Myeloid Leukemia ◽

Cytoplasmic Tail ◽

Myelogenous Leukemia ◽

Stem Cell Marker ◽

Cell Surface Glycoprotein ◽

Hematopoietic Stem

Abstract Abstract 2983 Acute myeloid leukemia (AML) originates from self-renewing leukemic stem cells (LSCs), an ultimate therapeutic target for AML. We have reported that the T-cell immunoglobulin mucin-3 (TIM-3) is expressed on LSCs in most types of AML but not on normal hematopoietic stem cells (HSCs). TIM-3+ AML cells reconstituted human AML in immunodeficient mice, whereas TIM3− AML cells did not, suggesting that the TIM-3+ population contains all functional LSCs. We established an anti-human TIM-3 mouse IgG2a antibody having complement-dependent and antibody-dependent cellular cytotoxic activities. This antibody did not harm reconstitution of normal human HSCs, but blocked engraftment of AML after xenotransplantation. Furthermore, when it is administered into mice grafted with human AML, this treatment dramatically diminished their leukemic burden, and eliminated LSCs capable of reconstituting human AML in secondary recipients (Kikushige et al, Cell Stem Cell, 2010).We extended the analysis of TIM-3 expression into various types of human hematological malignancies, and found that human TIM-3 is expressed in the vast majority of CD34+CD38− LSCs of human myeloid malignancies including chronic myeloid leukemia, chronic myelomonocytic leukemia and myelodysplastic syndromes (MDS). Although TIM-3 was not expressed in CD34+CD38− stem cell fraction in normal bone marrow cells, TIM-3 was progressively up-regulated in this population of MDS, along with disease progression into leukemia: The average percentages of TIM-3+ cells in the CD34+CD38− population was 7.8% in RCMD (n=10), 19.2% in RAEB-1 (n=10), 84.0% in RAEB-2 (n=10) and 92.2% in overt AML (n=10). Thus, TIM-3 might be useful to isolate malignant stem cells responsible for progression into AML in MDS patients. The close association of TIM-3 expression with transformation into AML led us to hypothesize that TIM-3 itself has a function in AML stem cell development. TIM-3 is type 1 cell-surface glycoprotein and has a structure that includes an N-terminal immunoglobulin variable domain followed by a mucin domain, a transmembrane domain and a cytoplasmic tail. Tyrosine residues are clustered in the cytoplasmic tail, suggesting that TIM-3 can induce signal transduction in TIM-3+ AML cells. Previous reports have shown that galectin-9 and HMGB-1 are the ligand of TIM-3 in lymphocytes and dendritic cells. TIM-3 is reported to signal differently in lymphocytes and myeloid cells, because TIM-3 ligation results in different patterns of tyrosine phosphorylation in these cell types, suggesting that TIM-3 has lineage- or cellular context-dependent signal transduction pathways or functions. Therefore, we considered that it should be critical to identify the function of TIM-3 in primary AML cells. We cultured TIM-3+ AML cells in the presence or absence of galectin-9 or HMGB-1, and performed cDNA microarray analysis to find genes activated in response to TIM-3 ligation. Interestingly, pro-apoptotic genes such as BAX and SIVA were significantly down-regulated in the presence of galectin-9 or HMGB-1, suggesting that TIM-3 signaling could promote survival of TIM-3-expressing LSCs. These data suggest that TIM-3 is a surface marker useful to track malignant LSCs in progression from MDS to AML, and TIM-3 may function for maintenance of LSC through inducing survival-promoting signaling. Disclosures: No relevant conflicts of interest to declare.

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TIM-3, a Leukemia Stem Cell Marker, Plays a Role In Leukemic Transformation Through Autocrine Stimulatory Signaling By Its Ligand, Galectin-9

Blood ◽

10.1182/blood.v122.21.4196.4196 ◽

2013 ◽

Vol 122 (21) ◽

pp. 4196-4196

Author(s):

Yoshikane Kikushige ◽

Junichiro Yuda ◽

Takahiro Shima ◽

Toshihiro Miyamoto ◽

Koichi Akashi

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Myeloid Leukemia ◽

Transmembrane Domain ◽

Cytoplasmic Tail ◽

Surface Glycoprotein ◽

Leukemic Cells ◽

Stem Cell Marker ◽

Cell Surface Glycoprotein ◽

Hematopoietic Stem

Abstract Acute myeloid leukemia (AML) originates from self-renewing leukemic stem cells (LSCs), an ultimate therapeutic target for AML. We have reported that the T-cell immunoglobulin mucin-3 (TIM-3) is expressed on LSCs in most types of AML but not on normal hematopoietic stem cells (HSCs) (Kikushige et al, Cell Stem Cell, 2010). We extended the analysis of TIM-3 expression into various types of human hematological malignancies, and found that human TIM-3 is expressed in the vast majority of CD34+CD38- LSCs of human myeloid malignancies including chronic myeloid leukemia, chronic myelomonocytic leukemia and myelodysplastic syndromes (MDS). Although CD34+CD38- normal bone marrow stem cells do not express TIM-3, TIM-3 is expressed in the CD34+CD38- population in MDS, and is further up-regulated with progression into leukemia. The average percentages of TIM-3+ cells in the CD34+CD38- population was 7.8% in RCMD (n=10), 19.2% in RAEB-1 (n=10), 84.0% in RAEB-2 (n=10) and 92.2% in overt AML (n=10). The close association of TIM-3 expression with transformation into AML led us to hypothesize that TIM-3 itself has a function in AML stem cell development. TIM-3 is a type 1 cell-surface glycoprotein and has a structure that includes an N-terminal immunoglobulin variable domain followed by a mucin domain, a transmembrane domain and a cytoplasmic tail. Tyrosine residues are clustered in the cytoplasmic tail, suggesting that TIM-3 can induce signal transduction in TIM-3+ AML cells. To understand the function of TIM-3, we investigated the interaction between TIM-3 and its ligand galectin-9 in AML LSCs. We found that AML patients showed significantly higher serum galectin-9 concentration than healthy individuals (healthy controls: 18.3+4.3 pg/ml, AML patients: 139.1+33.4 pg/ml, P<0.05). Unexpectedly, we found that leukemic cells expressed a high level of galectin-9 protein, as compared to other hematopoietic cells including T cells, B cells and monocytes. Using KASUMI-3 (TIM-3+ AML cell line) and primary AML samples, we confirmed that AML cells could secrete galectin-9 after TLR stimulation in vitro. Furthermore, microarray analysis demonstrated that TIM-3 stimulation by the physiological concentration of galectin-9 induced significant gene expression changes toward pro-survival axis including up-regulation of MCL-1, the important survival factor for HSCs and LSCs. These results collectively suggest that AML cells can produce and secrete galectin-9, and galectin-9 can bind and stimulate TIM-3-expressing AML cells including LSCs in an autocrine manner to support their survival or leukemia progression. Disclosures: Miyamoto: Kyushu University Hospital: Employment.

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A Novel, Myeloid Transcription Factor, C/EBPε, Is Upregulated During Granulocytic, But Not Monocytic, Differentiation

Blood ◽

10.1182/blood.v90.7.2591.2591_2591_2600 ◽

1997 ◽

Vol 90 (7) ◽

pp. 2591-2600 ◽

Cited By ~ 9

Author(s):

Roberta Morosetti ◽

Dorothy J. Park ◽

Alexey M. Chumakov ◽

Isabelle Grillier ◽

Masaaki Shiohara ◽

...

Keyword(s):

Stem Cells ◽

Transcription Factor ◽

Hematopoietic Stem Cells ◽

Cell Line ◽

Cell Lines ◽

Myeloid Leukemia ◽

Leukemia Cell ◽

Rt Pcr ◽

Hematopoietic Stem ◽

Nb4 Cells

Human C/EBPε is a newly cloned CCAAT/enhancer-binding transcription factor. Initial studies indicated it may be an important regulator of human myelopoiesis. To elucidate the range of expression of C/EBPε, we used reverse transcription-polymerase chain reaction (RT-PCR) analysis and examined its expression in 28 hematopoietic and 14 nonhematopoietic cell lines, 16 fresh myeloid leukemia samples, and normal human hematopoietic stem cells and their mature progeny. Prominent expression of C/EBPε mRNA occurred in the late myeloblastic and promyelocytic cell lines (NB4, HL60, GFD8), the myelomonoblastic cell lines (U937 and THP-1), the early myeloblast cell lines (ML1, KCL22, MDS92), and the T-cell lymphoblastic leukemia cell lines CEM and HSB-2. For the acute promyelocytic leukemia cell line NB4, C/EBPε was the only C/EBP family member that was easily detected by RT-PCR. No C/EBPε mRNA was found in erythroid, megakaryocyte, basophil, B lymphoid, or nonhematopoietic cell lines. Most acute myeloid leukemia samples (11 of 12) from patients expressed C/EBPε. Northern blot and RT-PCR analyses showed that C/EBPε mRNA decreased when the HL60 and KG-1 myeloblast cell lines were induced to differentiate toward macrophages. Similarly, Western blot analysis showed that expression of C/EBPε protein was either unchanged or decreased slightly as the promyelocytic cell line NB4 differentiated down the macrophage-like pathway after treatment with a potent vitamin D3 analog (KH1060). In contrast, C/EBPε protein levels increased dramatically as NB4 cells were induced to differentiate down the granulocytic pathway after exposure to 9-cis retinoic acid. Furthermore, very early, normal hematopoietic stem cells (CD34+/CD38−), purified from humans had very weak expression of C/EBPε mRNA, but levels increased as these cells differentiated towards granulocytes. Likewise, purified granulocytes appeared to express higher levels of C/EBPε mRNA than purified macrophages. Addition of phosphothiolated antisense, but not sense oligonucleotides to C/EBPε, decreased clonal growth of HL-60 and NB4 cells by about 50% compared with control cultures. Taken together, our results indicate that expression of C/EBPε is restricted to hematopoietic tissues, especially myeloid cells as they differentiate towards granulocytes and inhibition of its expression in HL-60 and NB4 myeloblasts and promyelocytes decreased their proliferative capacity. Therefore, this transcriptional factor may play an important role in the process of normal myeloid development.

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Dissecting the Immune Cell Progeny of CAR-Expressing Hematopoietic Stem Cells in a Humanized Mouse Model

Blood ◽

10.1182/blood-2019-129746 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4640-4640

Author(s):

Heng-Yi Liu ◽

Nezia Rahman ◽

Tzu-Ting Chiou ◽

Satiro N. De Oliveira

Keyword(s):

Stem Cells ◽

T Cells ◽

T Cell ◽

Hematopoietic Stem Cells ◽

Cell Lines ◽

Immune Cells ◽

Research Funding ◽

Humanized Mice ◽

Tumor Challenge ◽

Hematopoietic Stem

Background: Chemotherapy-refractory or recurrent B-lineage leukemias and lymphomas yield less than 50% of chance of cure. Therapy with autologous T-cells expressing chimeric antigen receptors (CAR) have led to complete remissions, but the effector cells may not persist, limiting clinical efficacy. Our hypothesis is the modification of hematopoietic stem cells (HSC) with anti-CD19 CAR will lead to persistent generation of multilineage target-specific immune cells, enhancing graft-versus-cancer activity and leading to development of immunological memory. Design/Methods: We generated second-generation CD28- and 4-1BB-costimulated CD19-specific CAR constructs using third-generation lentiviral vectors for modification of human HSC for assessment in vivo in NSG mice engrafted neonatally with human CD34-positive cells. Cells were harvested from bone marrows, spleens, thymus and peripheral blood at different time points for evaluation by flow cytometry and ddPCR for vector copy numbers. Cohorts of mice received tumor challenge with subcutaneous injection of lymphoma cell lines. Results: Gene modification of HSC with CD19-specific CAR did not impair differentiation or proliferation in humanized mice, leading to CAR-expressing cell progeny in myeloid, NK and T-cells. Humanized NSG engrafted with CAR-modified HSC presented similar humanization rates to non-modified HSC, with multilineage CAR-expressing cells present in all tissues with stable levels up to 44 weeks post-transplant. No animals engrafted with CAR-modified HSC presented autoimmunity or inflammation. T-cell populations were identified at higher rates in humanized mice with CAR-modified HSC in comparison to mice engrafted with non-modified HSC. CAR-modified HSC led to development of T-cell effector memory and T-cell central memory phenotypes, confirming the development of long-lasting phenotypes due to directed antigen specificity. Mice engrafted with CAR-modified HSC successfully presented tumor growth inhibition and survival advantage at tumor challenge with lymphoma cell lines, with no difference between both constructs (62.5% survival for CD28-costimulated CAR and 66.6% for 41BB-costimulated CAR). In mice sacrificed due to tumor development, survival post-tumor injection was directly correlated with tumor infiltration by CAR T-cells. Conclusions: CAR modification of human HSC for cancer immunotherapy is feasible and continuously generates CAR-bearing cells in multiple lineages of immune cells. Targeting of different malignancies can be achieved by adjusting target specificity, and this approach can augment the anti-lymphoma activity in autologous HSC recipients. It bears decreased morbidity and mortality and offers alternative therapeutic approach for patients with no available sources for allogeneic transplantation, benefiting ethnic minorities. Disclosures De Oliveira: National Institute for Health Research Biomedical Research Centre at Great Ormond Street Hospital for Children NHS Foundation Trust and University College London: Research Funding; NIAID, NHI: Research Funding; Medical Research Council: Research Funding; CIRM: Research Funding; National Gene Vector Repository: Research Funding.

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Identification of BCR/ABL-negative primitive hematopoietic progenitor cells within chronic myeloid leukemia marrow

Blood ◽

10.1182/blood.v81.3.801.bloodjournal813801 ◽

1993 ◽

Vol 81 (3) ◽

pp. 801-807 ◽

Cited By ~ 1

Author(s):

T Leemhuis ◽

D Leibowitz ◽

G Cox ◽

R Silver ◽

EF Srour ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Chronic Myeloid Leukemia ◽

Progenitor Cells ◽

Myeloid Leukemia ◽

Chronic Phase ◽

Polymerase Chain Reaction Analysis ◽

Hematopoietic Progenitor Cells ◽

Hematopoietic Progenitor ◽

Hematopoietic Stem

Chronic myeloid leukemia (CML) is a malignant disorder of the hematopoietic stem cell. It has been shown that normal stem cells coexist with malignant stem cells in the bone marrow of patients with chronic-phase CML. To characterize the primitive hematopoietic progenitor cells within CML marrow, CD34+DR- and CD34+DR+ cells were isolated using centrifugal elutriation, monoclonal antibody labeling, and flow cytometric cell sorting. Polymerase chain reaction analysis of RNA samples from these CD34+ subpopulations was used to detect the presence of the BCR/ABL translocation characteristic of CML. The CD34+DR+ subpopulation contained BCR/ABL(+) cells in 11 of 12 marrow samples studied, whereas the CD34+DR- subpopulation contained BCR/ABL(+) cells in 6 of 9 CML marrow specimens. These cell populations were assayed for hematopoietic progenitor cells, and individual hematopoietic colonies were analyzed by PCR for their BCR/ABL status. Results from six patients showed that nearly half of the myeloid colonies cloned from CD34+DR- cells were BCR/ABL(+), although the CD34+DR- subpopulation contained significantly fewer BCR/ABL(+) progenitor cells than either low-density bone marrow (LDBM) or the CD34+DR+ fraction. These CD34+ cells were also used to establish stromal cell-free long-term bone marrow cultures to assess the BCR/ABL status of hematopoietic stem cells within these CML marrow populations. After 28 days in culture, three of five cultures initiated with CD34+DR- cells produced BCR/ABL(-) cells. By contrast, only one of eight cultures initiated with CD34+DR+ cells were BCR/ABL(-) after 28 days. These results indicate that the CD34+DR- subpopulation of CML marrow still contains leukemic progenitor cells, although to a lesser extent than either LDBM or CD34+DR+ cells.

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Cellular and molecular characterization of the role of the flk-2/flt-3 receptor tyrosine kinase in hematopoietic stem cells

Blood ◽

10.1182/blood.v84.8.2422.bloodjournal8482422 ◽

1994 ◽

Vol 84 (8) ◽

pp. 2422-2430 ◽

Cited By ~ 8

Author(s):

FC Zeigler ◽

BD Bennett ◽

CT Jordan ◽

SD Spencer ◽

S Baumhueter ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Tyrosine Kinase ◽

Hematopoietic Stem Cell ◽

Receptor Tyrosine Kinase ◽

Lymphoid Cells ◽

Stem Cell Population ◽

Cell Populations ◽

Hematopoietic Stem ◽

Stem Cell Populations

The flk-2/flt-3 receptor tyrosine kinase was cloned from a hematopoietic stem cell population and is considered to play a potential role in the developmental fate of the stem cell. Using antibodies derived against the extracellular domain of the receptor, we show that stem cells from both murine fetal liver and bone marrow can express flk-2/flt-3. However, in both these tissues, there are stem cell populations that do not express the receptor. Cell cycle analysis shows that stem cells that do not express the receptor have a greater percentage of the population in G0 when compared with the flk-2/flt-3- positive population. Development of agonist antibodies to the receptor shows a proliferative role for the receptor in stem cell populations. Stimulation with an agonist antibody gives rise to an expansion of both myeloid and lymphoid cells and this effect is enhanced by the addition of kit ligand. These studies serve to further illustrate the importance of the flk-2/flt-3 receptor in the regulation of the hematopoietic stem cell.

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