PRL2 Maintains Hematopoietic Stem and Progenitor Cells Through Regulating SCF/KIT Signaling

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3674-3674
Author(s):  
Michihiro Kobayashi ◽  
Yuanshu Dong ◽  
Hao Yu ◽  
Yunpeng Bai ◽  
Sisi Chen ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Progenitor Cell ◽  
Conflicts Of Interest ◽  
Critical Role ◽  
Hematopoietic Progenitor Cell ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Abstract The phosphatase of regenerating liver family of phosphatases, consisting of PRL1, PRL2 and PRL3, represents an intriguing group of proteins implicated in cell proliferation and tumorigenesis. However, the role of PRLs in normal and malignant hematopoiesis is largely unknown. While SCF/KIT signaling plays an important role in hematopoietic stem and progenitor cell (HSPC) maintenance, how SCF/KIT signaling is regulated in HSPCs remains poorly understood. We here report that PRL2 regulates HSPC maintenance through regulating SCF/KIT signaling. To define the role of PRL2 in hematopoiesis, we analyzed the hematopoietic stem cell (HSC) behavior in Prl2 deficient mice generated by our group. Prl2 deficiency results in ineffective hematopoiesis and impairs the long-term repopulating ability of HSCs. In addition, Prl2 null HSPCs are less proliferative and show decreased colony formation in response to SCF stimulation. Furthermore, Prl2 null HSPCs show reduced activation of the PI3K/AKT and ERK signaling in steady state and following SCF stimulation. Importantly, we found that PRL2 associates with KIT and the ability of PRL2 to enhance SCF signaling depends on its enzymatic activity, demonstrating that PRL2 mediates SCF/KIT signaling in HSPCs. Thus, PRL2 plays a critical role in hematopoietic stem and progenitor cell maintenance through regulating SCF/KIT signaling. Furthermore, loss of Prl2 decreased the ability of oncogenic KITD814V mutant in promoting hematopoietic progenitor cell proliferation and in activation of signaling pathways. We also checked the expression of PRL2 proteins in human AML cell lines and found increased level of PRL2 proteins in some acute myeloid leukemia (AML) cells compared with normal human bone marrow cells, indicating that PRL2 may play a pathological role in AML. Our results suggest that the PRL2 phosphatase may be a druggable target in myeloproliferative disease (MPD) and acute myeloid leukemia (AML) with oncogenic KIT mutations. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Critical Role of Lama4 for Hematopoiesis Regeneration and Acute Myeloid Leukemia Progression

Blood ◽  
2021 ◽  
Author(s):  
Huan Cai ◽  
Makoto Kondo ◽  
Lakshmi Sandhow ◽  
Pingnan Xiao ◽  
Anne-Sofie Johansson ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Cell Proliferation ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Critical Role ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Bm Niche ◽  
Acute Myeloid

Impairement of normal hmatopoiesis and leukemia progression are two well-linked processes during leukemia development and controlled by the bone marrow (BM) niche. Extracellular matrix proteins including laminin are important BM niche components. However, their role in hematopoiesis regeneration and leukemia is unknown. Laminin α4 (Lama4), a major receptor-binding chain of several laminins, is altered in BM niches in mice with acute myeloid leukemia (AML). So far, the impact of Lama4 on leukemia progression remains unknown. We here report that Lama4 deletion in mice resulted in impaired hematopoiesis regeneration following irradiation-induced stress, which is accompanied with altered BM niche composition and inflammation. Importantly, in a transplantation-induced MLL-AF9 AML mouse model, we demonstrate accelerated AML progression and relapse in Lama4-/-mice. Upon AML exposure, Lama4-/- mesenchymal stem cells (MSCs) exhibited dramatic molecular alterations including upregulation of inflammatory cytokines that favor AML growth. Lama4-/- MSCs displayed increased anti-oxidant activities and promoted AML stem cell proliferation and chemoresistance to cytarabine, which was accompanied by increased mitochondrial transfer from the MSCs to AML cells and reduced reactive oxygen species in AML cells in vitro. Similarly, we detected lower levels of reactive oxygen species in AML cells from Lama4-/- mice post-cytarabine treatment. Notably, LAMA4 inhibition or knockdown in human MSCs promoted human AML cell proliferation and chemoprotection. Together, our study for the first time demonstrates a critical role of Lama4 in impeding AML progression and chemoresistance. Targeting Lama4 signaling pathways may offer potential new therapeutic options for AML.

The GSK3β-Phosphorylation Sites in the DEK-Portion Are Indispensable for the Leukemogenic Potential of the DEK/CAN Fusion Protein in t(6;9)-Positive Acute Myeloid Leukemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3574-3574
Author(s):  
Claudia Oancea ◽  
Maria Heinßmann ◽  
Nathalie Guillen ◽  
Oliver G. Ottmann ◽  
Martin Ruthardt
Keyword(s):  
Acute Myeloid Leukemia ◽  
Fusion Protein ◽  
Myeloid Leukemia ◽  
Conflicts Of Interest ◽  
Glycogen Synthase ◽  
Confocal Laser ◽  
Phosphorylation Sites ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Abstract The t(6,9)(p23,q34) translocation occurs in 1-5% of adult patients with acute myeloid leukemia (AML). It is associated with a poor prognosis and defines a high risk group of AML in the WHO classification. The t(6;9) is in most of the cases the only cytogenetic aberration at diagnosis. The hallmark of t(6;9)-positive AML is the DEK/CAN fusion protein. DEK/CAN is a leukemogenic oncogene, but little is known about the molecular mechanism of DEK/CAN-induced leukemogenesis. The 165 kDa DEK/CAN phosphoprotein is encoded by a single transcript of 5.5Kb. The DEK portion of the DEK/CAN contains all the major functional domains of DEK mediating DNA-binding and multimerization. DEK increases life span of primary cells in culture by inhibiting cellular senescence and apoptosis. Post-translational modifications of DEK, mainly phosphorylation, influence the activity of DEK; unphosphorylated DEK has a higher affinity for DNA than the phosphorylated form, which in turn has a higher ability for multimerization. The main kinases that phosphorylate DEK are Glycogen synthase kinase 3 β (GSK3β) and Casein kinase 2 (CK2). The respective phosphorylation sites are conserved in the DEK portion of DEK/CAN. However, little is known about the role of phosphorylation for the biological functions of DEK/CAN. Therefore we generated several mutants of DEK and DEK/CAN by point-mutating the putative GSK3β-sites (ΔP1) from S to A and by deleting the CK2 sites in addition to these mutations (ΔP2). The reduction of S/T phosphorylation was confirmed by a ProQ staining and affinity chromatography on lysates of 293T cells expressing DEK, DEK/CAN and the respective ΔP1 or ΔP2 mutants. Further biological and biochemical consequences of these mutations for DEK and DEK/CAN were investigated in murine factor dependent 32D progenitor cells and in primary murine Sca1+/lin- hematopoietic stem cells (HSC), retrovirally or lentivirally transduced with DEK, DEK/CAN and/or their phosphorylation mutants ΔP1 or ΔP2, respectively. Here we report that the loss of the GSK3β- and CK2-phosphorylation sites did not interfere with the subnuclear localization of either DEK or DEK/CAN as revealed either by subnuclear fractionation experiments or by co-localization with native DEK/CAN in confocal laser scan microscopy assays on 32D cells co-expressing DEK/CAN and ΔP1-DEK/CAN or ΔP2-DEK/CAN. In contrast, the destruction of GSK3β-phosphorylation sites not only led to a loss of apoptosis inhibition by DEK and DEK/CAN upon factor withdrawal in 32D cells, but also abolished the increased self renewal potential of DEK/CAN-positive HSC. In fact DEK/CAN-positive HSCs significantly increased colony numbers in colony forming units spleen-day 12 (CFU-S12) assays as compared to empty vector controls, whereas ΔP1-DEK/CAN and ΔP2-DEK/CAN did not have any effect. In summary, our results suggest an important role of the GSK3β-phosphorylation for the DEK/CAN-induced leukemogenesis, which establishes the GSK3β-activity as a molecular target for therapeutic intervention in t(6;9)-positive AML. Disclosures No relevant conflicts of interest to declare.

scholarly journals Critical Role of c-Myc in Acute Myeloid Leukemia Involving Direct Regulation of miR-26a and Histone Methyltransferase EZH2

2011 ◽  
Vol 2 (5) ◽  
pp. 585-592 ◽  
Author(s):  
B. Salvatori ◽  
I. Iosue ◽  
N. Djodji Damas ◽  
A. Mangiavacchi ◽  
S. Chiaretti ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Critical Role ◽  
Histone Methyltransferase ◽  
Direct Regulation ◽  
Acute Myeloid

Alternative polyadenylation dysregulation contributes to the differentiation block of acute myeloid leukemia

Blood ◽  
2021 ◽  
Author(s):  
Amanda G Davis ◽  
Daniel T. Johnson ◽  
Dinghai Zheng ◽  
Ruijia Wang ◽  
Nathan D. Jayne ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Alternative Polyadenylation ◽  
Hematopoietic Stem ◽  
Global Trends ◽  
Protein Levels ◽  
Mtorc1 Signaling ◽  
Differentiation Block ◽  
Acute Myeloid

Post-transcriptional regulation has emerged as a driver for leukemia development and an avenue for therapeutic targeting. Among post-transcriptional processes, alternative polyadenylation (APA) is globally dysregulated across cancer types. However, limited studies have focused on the prevalence and role of APA in myeloid leukemia. Furthermore, it is poorly understood how altered poly(A) site (PAS) usage of individual genes contributes to malignancy or whether targeting global APA patterns might alter oncogenic potential. In this study, we examined global APA dysregulation in acute myeloid leukemia (AML) patients by performing 3' Region Extraction And Deep Sequencing (3'READS) on a subset of AML patient samples along with healthy hematopoietic stem and progenitor cells (HSPCs) and by analyzing publicly available data from a broad AML patient cohort. We show that patient cells exhibit global 3' untranslated region (UTR) shortening and coding sequence (CDS) lengthening due to differences in PAS usage. Among APA regulators, expression of FIP1L1, one of the core cleavage and polyadenylation factors, correlated with the degree of APA dysregulation in our 3'READS dataset. Targeting global APA by FIP1L1 knockdown reversed the global trends seen in patients. Importantly, FIP1L1 knockdown induced differentiation of t(8;21) cells by promoting 3'UTR lengthening and downregulation of the fusion oncoprotein AML1-ETO. In non-t(8;21) cells, FIP1L1 knockdown also promoted differentiation by attenuating mTORC1 signaling and reducing MYC protein levels. Our study provides mechanistic insights into the role of APA in AML pathogenesis and indicates that targeting global APA patterns can overcome the differentiation block of AML patients.

scholarly journals SETDB1 mediated histone H3 lysine 9 methylation suppresses MLL-fusion target expression and leukemic transformation

Haematologica ◽  
2019 ◽  
Vol 105 (9) ◽  
pp. 2273-2285 ◽  
Author(s):  
James Ropa ◽  
Nirmalya Saha ◽  
Hsiangyu Hu ◽  
Luke F. Peterson ◽  
Moshe Talpaz ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Target Genes ◽  
Critical Role ◽  
High Expression ◽  
Leukemia Cells ◽  
Biological Impact ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Epigenetic regulators play a critical role in normal and malignant hematopoiesis. Deregulation, including epigenetic deregulation, of the HOXA gene cluster drives transformation of about 50% of acute myeloid leukemia. We recently showed that the Histone 3 Lysine 9 methyltransferase SETDB1 negatively regulates the expression of the pro-leukemic genes Hoxa9 and its cofactor Meis1 through deposition of promoter H3K9 trimethylation in MLL-AF9 leukemia cells. Here, we investigated the biological impact of altered SETDB1 expression and changes in H3K9 methylation on acute myeloid leukemia. We demonstrate that SETDB1 expression is correlated to disease status and overall survival in acute myeloid leukemia patients. We recapitulated these findings in mice, where high expression of SETDB1 delayed MLL-AF9 mediated disease progression by promoting differentiation of leukemia cells. We also explored the biological impact of treating normal and malignant hematopoietic cells with an H3K9 methyltransferase inhibitor, UNC0638. While myeloid leukemia cells demonstrate cytotoxicity to UNC0638 treatment, normal bone marrow cells exhibit an expansion of cKit+ hematopoietic stem and progenitor cells. Consistent with these data, we show that bone marrow treated with UNC0638 is more amenable to transformation by MLL-AF9. Next generation sequencing of leukemia cells shows that high expression of SETDB1 induces repressive changes to the promoter epigenome and downregulation of genes linked with acute myeloid leukemia, including Dock1 and the MLL-AF9 target genes Hoxa9, Six1, and others. These data reveal novel targets of SETDB1 in leukemia that point to a role for SETDB1 in negatively regulating pro-leukemic target genes and suppressing acute myeloid leukemia.

scholarly journals Gpr44 Mediates the Selenium-Dependent Anti-Leukemic Effect in Acute Myeloid Leukemia

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1835-1835
Author(s):  
Fenghua Qian ◽  
Fenghua Qian ◽  
Diwakar Tukaramrao ◽  
Jiayan Zhou ◽  
Nicole Palmiero ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Murine Model ◽  
Myeloid Leukemia ◽  
Hematopoietic Stem ◽  
Cell Counts ◽  
Pparγ Agonist ◽  
Acute Myeloid

Abstract Objectives The relapse of acute myeloid leukemia (AML) remains a significant concern due to persistent leukemia stem cells (LSCs) that are not targeted by existing therapies. LSCs show sensitivity to endogenous cyclopentenone prostaglandin J (CyPG) metabolites that are increased by dietary trace element selenium (Se), which is significantly decreased in AML patients. We investigated the anti-leukemic effect of Se supplementation in AML via mechanisms involving the activation of the membrane-bound G-protein coupled receptor 44 (Gpr44) and the intracellular receptor, peroxisome proliferator-activated receptor gamma (PPARγ), by endogenous CyPGs. Methods A murine model of AML generated by transplantation of hematopoietic stem cells (HSCs- WT or Gpr44−/−) expressing human MLL-AF9 fusion oncoprotein, in the following experiments: To investigate the effect of Se supplementation on the outcome of AML, donor mice were maintained on either Se-adequate (Se-A; 0.08–0.1 ppm Se) or Se-supplemented (Se-S; 0.4 ppm Se) diets. Complete cell counts in peripheral blood were analyzed by hemavet. LSCs in bone marrow and spleen were analyzed by flow cytometry. To determine the role of Gpr44 activation in AML, mice were treated with Gpr44 agonists, CyPGs. LSCs in bone marrow and spleen were analyzed. Mice transplanted with Gpr44−/- AML cells were compared with mice transplanted with wild type AML cells and the progression of the disease was followed as above. To determine the role of PPARγ activation in AML, PPARγ agonist (Rosiglitazone, 6 mg/kg, i.p, 14 d) and antagonist (GW9662, 1 mg/kg, i.p. once every other day, 7 injections) were applied to Se-S mice transplanted with Gpr44−/- AML cells and disease progression was followed. Results Se supplementation at supraphysiological levels alleviated the disease via the elimination of LSCs in a murine model of AML. CyPGs induced by Se supplementation mediate the apoptosis in LSCs via the activation of Gpr44 and PPARγ. Conclusions Endogenous CyPGs produced upon supplementation with Se at supraphysiological levels improved the outcome of AML by targeting LSCs to apoptosis via the activation of two receptors, Gpr44 and PPARg. Funding Sources NIH DK 07,7152; CA 175,576; CA 162,665. Office of Dietary Supplements, USDA Hatch funds PEN04605, Accession # 1,010,021 (KSP, RFP).

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.

Ezh2 Plays a Critical Role in the Progression of MLL-AF9-Induced Acute Myeloid Leukemia

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 57-57
Author(s):  
Satomi Tanaka ◽  
Goro Sashida ◽  
Satoru Miyagi ◽  
Koutaro Yokote ◽  
Chiaki Nakaseko ◽  
...  
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Target Genes ◽  
Nuclear Translocation ◽  
Conflicts Of Interest ◽  
Critical Role ◽  
Histone H3 ◽  
Chip Sequencing ◽  
Acute Myeloid

Abstract Abstract 57 The polycomb group proteins function in gene silencing through histone modifications. They have been characterized as a general regulator of stem cells, but also play a critical role in cancer. EZH2 is a catalytic component of the polycomb repressive complex 2 (PRC2) and tri-methylates histone H3 at lysine 27 to transcriptionally repress the target genes. Although EZH2 is over-expressed in various cancers including hematological malignancies, it remains unknown how EZH2 contributes to the initiation and/or progression of acute myeloid leukemia (AML). To understand the role of EZH2 in AML, we transformed granulocyte macrophage progenitors (GMPs) from Cre-ERT;Ezh2+/+ and Cre-ERT;Ezh2flox/flox mice with the MLL-AF9 fusion gene. Then, Ezh2 was deleted by inducing nuclear translocation of Cre by adding tamoxifen to culture. We found that proliferation of Ezh2δ/δ transformed cells was severely compromised upon deletion of Ezh2 (Ezh2δ/δ) in liquid culture. They gave rise to a significantly reduced number of colonies in replating assays. Of note, while Ezh2+/+ cells formed compact colonies composed of immature myeloblasts, Ezh2δ/δ cells formed dispersed colonies composed of differentiated myeloid cells. We next transplanted Cre-ERT;Ezh2+/+ and Cre-ERT;Ezh2flox/flox GMPs transformed by MLL-AF9 into recipient mice. All the recipient mice developed AML by 3 weeks after transplantation. At 3 weeks after transplantation, we depleted Ezh2 by intraperitoneal injection of tamoxifen. Deletion of Ezh2 significantly prolonged the survival of the recipient mice (60 days vs. 76 days, p<0.0001), although all the mice eventually died of leukemia. Nonetheless, as was detected in vitro, Ezh2δ/δ AML cells in BM were apparently differentiated in morphology compared with the control. Ezh2δ/δ AML cells in BM gave rise to 10-fold fewer colonies in methylcellulose medium compared with Ezh2+/+ AML cells, and again showed an obvious tendency of differentiation. These observations imply that Ezh2 is critical for the progression of MLL-AF9 AML and maintains the immature state of AML cells. To elucidate the mechanism how Ezh2 promotes the progression of MLL-AF9-induced AML, we examined the genome-wide distribution of tri-methylation of histone H3 at lysine 27 (H3K27me3) by ChIP-sequencing and microarray-based expression analysis. ChIP-sequencing using Ezh2+/+ and Ezh2δ/δ BM AML cells identified 3525 and 89 genes exhibiting a ≧ 10-fold enrichment in H3K27me3 levels in Ezh2+/+ and Ezh2δ/δ AML cells, respectively, confirming a drastic reduction in the levels of global H3K27me3 in the absence of Ezh2. Microarray analysis using lineage marker (except for Mac1)−Sca-1−c-Kit+FcγRII/IIIhi BM AML cells revealed 252 upregulated and 154 downregulated genes (≧ 2-fold) in Ezh2δ/δ AML cells compared with Ezh2+/+ AML cells. Of interest, the absence of Ezh2 did not affect the transcriptional activation of the major target genes of MLL-AF9, including HoxA9 and Meis1. Because Ezh2 functions as transcriptional repressor, de-repressed genes could be direct targets of Ezh2. Based on these data, we are now engaged in further comprehensive analysis to narrow down the direct target genes of Ezh2 responsible for the progression of AML. Collectively, our findings suggest that Ezh2 is the major enzyme for H3K27me3 in AML and contributes to the progression of AML by regulating transcription a cohort of genes that are supposedly relevant to the self-renewal capacity and perturbed differentiation of AML stem cells. Disclosures: No relevant conflicts of interest to declare.

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