Evi-1 is a transcriptional target of mixed-lineage leukemia oncoproteins in hematopoietic stem cells

Blood ◽  
2011 ◽  
Vol 117 (23) ◽  
pp. 6304-6314 ◽  
Author(s):  
Shunya Arai ◽  
Akihide Yoshimi ◽  
Munetake Shimabe ◽  
Motoshi Ichikawa ◽  
Masahiro Nakagawa ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Myeloid Leukemia ◽  
Mixed Lineage Leukemia ◽  
Aberrant Expression ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Abstract Ecotropic viral integration site-1 (Evi-1) is a nuclear transcription factor that plays an essential role in the regulation of hematopoietic stem cells. Aberrant expression of Evi-1 has been reported in up to 10% of patients with acute myeloid leukemia and is a diagnostic marker that predicts a poor outcome. Although chromosomal rearrangement involving the Evi-1 gene is one of the major causes of Evi-1 activation, overexpression of Evi-1 is detected in a subgroup of acute myeloid leukemia patients without any chromosomal abnormalities, which indicates the presence of other mechanisms for Evi-1 activation. In this study, we found that Evi-1 is frequently up-regulated in bone marrow cells transformed by the mixed-lineage leukemia (MLL) chimeric genes MLL-ENL or MLL-AF9. Analysis of the Evi-1 gene promoter region revealed that MLL-ENL activates transcription of Evi-1. MLL-ENL–mediated up-regulation of Evi-1 occurs exclusively in the undifferentiated hematopoietic population, in which Evi-1 particularly contributes to the propagation of MLL-ENL–immortalized cells. Furthermore, gene-expression analysis of human acute myeloid leukemia cases demonstrated the stem cell–like gene-expression signature of MLL-rearranged leukemia with high levels of Evi-1. Our findings indicate that Evi-1 is one of the targets of MLL oncoproteins and is selectively activated in hematopoietic stem cell–derived MLL leukemic cells.

MicroRNA-29a Is An Oncogene in Acute Myeloid Leukemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 683-683
Author(s):  
Christopher Y. Park ◽  
Yoon-Chi Han ◽  
Govind Bhagat ◽  
Jian-Bing Fan ◽  
Irving L Weissman ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Hematopoietic Stem Cells ◽  
Mirna Expression ◽  
Myeloid Leukemia ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Abstract microRNAs (miRNAs) are short, non-protein encoding RNAs that bind to the 3′UTR’s of target mRNAs and negatively regulate gene expression by facilitating mRNA degradation or translational inhibition. Aberrant miRNA expression is well-documented in both solid and hematopoietic malignancies, and a number of recent miRNA profiling studies have identified miRNAs associated with specific human acute myeloid leukemia (AML) cytogenetic groups as well as miRNAs that may prognosticate clinical outcomes in AML patients. Unfortunately, these studies do not directly address the functional role of miRNAs in AML. In fact, there is no direct functional evidence that miRNAs are required for AML development or maintenance. Herein, we report on our recent efforts to elucidate the role of miRNAs in AML stem cells. miRNA expression profiling of AML stem cells and their normal counterparts, hematopoietic stem cells (HSC) and committed progenitors, reveals that miR-29a is highly expressed in human hematopoietic stem cells (HSC) and human AML relative to normal committed progenitors. Ectopic expression of miR-29a in mouse HSC/progenitors is sufficient to induce a myeloproliferative disorder (MPD) that progresses to AML. During the MPD phase of the disease, miR-29a alters the composition of committed myeloid progenitors, significantly expedites cell cycle progression, and promotes proliferation of hematopoietic progenitors at the level of the multipotent progenitor (MPP). These changes are manifested pathologically by marked granulocytic and megakaryocytic hyperplasia with hepatosplenomegaly. Mice with miR-29a-induced MPD uniformly progress to an AML that contains a leukemia stem cell (LSC) population that can serially transplant disease with as few as 20 purified LSC. Gene expression analysis reveals multiple tumor suppressors and cell cycle regulators downregulated in miR-29a expressing cells compared to wild type. We have demonstrated that one of these genes, Hbp1, is a bona fide miR-29a target, but knockdown of Hbp1 in vivo does not recapitulate the miR-29a phenotype. These data indicate that additional genes are required for miR-29a’s leukemogenic activity. In summary, our data demonstrate that miR-29a regulates early events in normal hematopoiesis and promotes myeloid differentiation and expansion. Moreover, they establish that misexpression of a single miRNA is sufficient to drive leukemogenesis, suggesting that therapeutic targeting of miRNAs may be an effective means of treating myeloid leukemias.

scholarly journals RNA m6A Modification Plays a Key Role in Maintaining Stem Cell Function in Normal and Malignant Hematopoiesis

2021 ◽  
Vol 9 ◽  
Author(s):  
Peipei Wang ◽  
Mengdie Feng ◽  
Guoqiang Han ◽  
Rong Yin ◽  
Yashu Li ◽  
...  
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Myeloid Leukemia ◽  
Cell Function ◽  
Leukemia Stem Cells ◽  
Hematopoietic Stem ◽  
Cellular Processes ◽  
Acute Myeloid

N6-methyladenosine (m6A) is a commonly modification of mammalian mRNAs and plays key roles in various cellular processes. Emerging evidence reveals the importance of RNA m6A modification in maintaining stem cell function in normal hematopoiesis and leukemogenesis. In this review, we first briefly summarize the latest advances in RNA m6A biology, and further highlight the roles of m6A writers, readers and erasers in normal hematopoiesis and acute myeloid leukemia. Moreover, we also discuss the mechanisms of these m6A modifiers in preserving the function of hematopoietic stem cells (HSCs) and leukemia stem cells (LSCs), as well as potential strategies for targeting m6A modification related pathways. Overall, we provide a comprehensive summary and our insights into the field of RNA m6A in normal hematopoiesis and leukemia pathogenesis.

scholarly journals Hematopoietic Stem Cells Are Intrinsically Protected Against MLL-ENL Mediated Transformation

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 839-839
Author(s):  
Amol Sanjay Ugale ◽  
Gudmundur Logi Norddahl ◽  
Martin Wahlestedt ◽  
Petter Säwén ◽  
Pekka Jaako ◽  
...  
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Hematopoietic Stem Cells ◽  
Mouse Models ◽  
Myeloid Leukemia ◽  
Mixed Lineage Leukemia ◽  
Hematopoietic Stem ◽  
Normal Differentiation ◽  
Acute Myeloid ◽  
Myeloid Progenitors

Abstract Studies on the developmental pathways of hematopoietic stem cells (HSCs) have led to roadmaps of differentiation and resulted in key information concerning lineage relationships and restriction points in the blood system. This knowledge is also central to understand the etiology of acute myeloid leukemia (AML), where recent work has proposed that the heterogeneity and aggressiveness of AML can associate with the developmental stage of transformation. Balanced chromosomal translocations that result in fusion proteins with aberrant transcriptional regulatory activities are frequent initiating events in acute myeloid leukemia, and a prototype family of such chimeric transcription factors is represented by fusions involving the mixed lineage leukemia-1 (MLL1) gene. Previous work using mouse models have suggested that at some stage of normal differentiation there is a loss of competence to induce AML. However discrepancies exists between these mouse models concerning the target cells of MLL fusion genes. While it is clear that cells can lose competence for leukemic transformation as part of their normal differentiation, the question remains whether the most primitive HSCs are always imbued with leukemogenic competency as part of their normal biology. To address this, we developed a Doxycycline inducible transgenic mouse model of the human chimeric transcription factor Mixed Lineage Leukemia-Eleven Nineteen Leukemia (MLL-ENL). Prospective isolations of candidate leukemia-initiating cells followed by adoptive transfers allowed us to detail leukemia-initiation and competence throughout the hematopoietic hierarchy. We show that AML can origin from multiple HPC subsets with intrinsic granulocytic/monocytic potential. Closely related myeloid progenitors displayed distinct leukemic- and functional capacity in response to physiological levels of MLL-ENL, highlighting the importance of a careful prospective isolation of progenitor populations. AML could also develop efficiently from common lymphoid progenitors, supporting a latent myeloid potential of these cells. By contrast, early commitment to the megakaryocytic/erythroid lineages was incompatible with leukemic development. By contrast, disease failed to arise from the most primitive progenitor subsets, including HSCs. Investigations of the immediate transcriptional responses to MLL-ENL showed evidence for a block in differentiation in both myeloid progenitors and HSCs, while MLL-ENL restricted cell cycle progression uniquely in HSCs. Our study highlights how an oncogene can exert unique functions depending on the developmental position of its cellular targets and demonstrate the existence of a mechanism, operational at the level of immature HSCs/progenitors, which act to prevent leukemic development. Figure 1 Graphical abstract Figure 1. Graphical abstract Disclosures No relevant conflicts of interest to declare.

scholarly journals CD9, a potential leukemia stem cell marker, regulates drug resistance and leukemia development in acute myeloid leukemia

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yongliang Liu ◽  
Guiqin Wang ◽  
Jiasi Zhang ◽  
Xue Chen ◽  
Huailong Xu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stem Cells ◽  
Drug Resistance ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Stem Cell Marker ◽  
Hematopoietic Stem ◽  
Chemotherapy Drugs ◽  
And Migration ◽  
Acute Myeloid

Abstract Background Leukemia stem cells (LSCs) are responsible for the initiation, progression, and relapse of acute myeloid leukemia (AML). Therefore, a therapeutic strategy targeting LSCs is a potential approach to eradicate AML. In this study, we aimed to identify LSC-specific surface markers and uncover the underlying mechanism of AML LSCs. Methods Microarray gene expression data were used to investigate candidate AML-LSC-specific markers. CD9 expression in AML cell lines, patients with AML, and normal donors was evaluated by flow cytometry (FC). The biological characteristics of CD9-positive (CD9+) cells were analyzed by in vitro proliferation, chemotherapeutic drug resistance, migration, and in vivo xenotransplantation assays. The molecular mechanism involved in CD9+ cell function was investigated by gene expression profiling. The effects of alpha-2-macroglobulin (A2M) on CD9+ cells were analyzed with regard to proliferation, drug resistance, and migration. Results CD9, a cell surface protein, was specifically expressed on AML LSCs but barely detected on normal hematopoietic stem cells (HSCs). CD9+ cells exhibit more resistance to chemotherapy drugs and higher migration potential than do CD9-negative (CD9−) cells. More importantly, CD9+ cells possess the ability to reconstitute human AML in immunocompromised mice and promote leukemia growth, suggesting that CD9+ cells define the LSC population. Furthermore, we identified that A2M plays a crucial role in maintaining CD9+ LSC stemness. Knockdown of A2M impairs drug resistance and migration of CD9+ cells. Conclusion Our findings suggest that CD9 is a new biomarker of AML LSCs and is a promising therapeutic target.

scholarly journals Evidence for malignant transformation in acute myeloid leukemia at the level of early hematopoietic stem cells by cytogenetic analysis of CD34+ subpopulations

Blood ◽  
1995 ◽  
Vol 86 (8) ◽  
pp. 2906-2912 ◽  
Author(s):  
D Haase ◽  
M Feuring-Buske ◽  
S Konemann ◽  
C Fonatsch ◽  
C Troff ◽  
...  
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Hematopoietic Stem Cells ◽  
Malignant Transformation ◽  
Cell Sorting ◽  
Myeloid Leukemia ◽  
De Novo ◽  
Leukemic Cells ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Acute myeloid leukemia (AML) is a heterogenous disease according to morphology, immunophenotype, and genetics. The retained capacity of differentiation is the basis for the phenotypic classification of the bulk population of leukemic blasts and the identification of distinct subpopulations. Within the hierarchy of hematopoietic development and differentiation it is still unknown at which stage the malignant transformation occurs. It was our aim to analyze the potential involvement of cells with the immunophenotype of pluripotent stem cells in the leukemic process by the use of cytogenetic and cell sorting techniques. Cytogenetic analyses of bone marrow aspirates were performed in 13 patients with AML (11 de novo and 2 secondary) and showed karyotype abnormalities in 10 cases [2q+, +4, 6p, t(6:9), 7, +8 in 1 patient each and inv(16) in 4 patients each]. Aliquots of the samples were fractionated by fluorescence-activated cell sorting of CD34+ cells. Two subpopulations, CD34+/CD38-(early hematopoietic stem cells) and CD34+/CD38+ (more mature progenitor cells), were screened for karyotype aberations as a marker for leukemic cells. Clonal abnormalities and evaluable metaphases were found in 8 highly purified CD34+/CD38-populations and in 9 of the CD34+/CD38-specimens, respectively. In the majority of cases (CD34+/CD38-, 6 of 8 informative samples; CD34+/CD38+, 5 of 9 informative samples), the highly purified CD34+ specimens also contained cytogenetically normal cells. Secondary, progression-associated chromosomal changes (+8, 12) were identified in the CD34+/CD38-cells of 2 patients. We conclude that clonal karyotypic abnormalities are frequently found in the stem cell-like (CD34+/CD38-) and more mature (CD34+/CD38+) populations of patients with AML, irrespective of the phenotype of the bulk population of leukemic blasts and of the primary or secondary character of the leukemia. Our data suggest that, in AML, malignant transformation as well as disease progression may occur at the level of CD34+/CD38-cells with multilineage potential.

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