Rac1 Gtpase Promotes Hematopoietic Stem Cell Migration, Self-Renewal and Participates in Leukemia Initiation and Maintenance

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2923-2923
Author(s):  
Shuying Chen ◽  
Qing Rao ◽  
Haiyan Xing ◽  
Jing Yu ◽  
Huan Li ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Cell Migration ◽  
Myeloid Leukemia ◽  
Leukemia Cells ◽  
Bone Marrow Niche ◽  
Hematopoietic Stem ◽  
Rac1 Gtpase ◽  
Acute Myeloid

Abstract Acute myeloid leukemia (AML) is a hematological malignancy resulting from the transformation of normal hematopoietic stem cell (HSC). Except for the intrinsic factors, it is acceptable that some extrinsic events from microenvironment could be the important co-factors in the development of leukemia. In addition to the specific component, as an extrinsic factor, interaction between HSC and bone marrow niche regulates HSCs fate. Disruption on the interactions also influences hematopoiesis. It has become evident that Rac members of Rho GTPases family are important molecules regulating HSCs interactions with hematopoietic microenvironment and activation of Rac1 are observed in a serials of leukemia cells. We previously reported that Rac1 is highly expressed in leukemia cells and found that activation of Rac1 GTPase lead to an increase in leukemia cells migration, chemotherapy resistance, quiescence and trafficking to bone marrow niche. Furthermore, we showed that Rac1 mediated the localization in niche is further attributable to the maintenance of LSC quiescence. In this study, we investigated the effects of active Rac1 GTPase in the transformation of HSC and determined if the activation of Rac1GTPase could promote the interaction of HSC with osteoblastic niche and further contribute to the leukomogenesis. By forced expression of a constitutively active form of Rac1 GTPase (Rac1 V12）in c-Kit+ hematopoietic stem/progenitor cell, we show that activation of Rac1 GTPase promotes cell migration, adhesion and colony formation, and also lead to an increase in the frequency of cells in quiescent state. Gene expression analysis shows that activation of Rac1 up-regulates the expression of several molecules that mediated the interaction of LSC with osteoblastic niche, as well as the cell cycle inhibitors such as p21, p27, and p57. Furthermore, we established a mouse model of acute myeloid leukemia by transduction murine c-kit+HSPC with Rac1 V12 combined with AML1-ETO9a, followed by transplantation into lethally irradiated mice. To investigate the role of Rac1 activation in leukemogenesis in vivo, we treated the AML1-ETO-Rac1 leukemia cells with Rac1 GTPase inhibitor EHT1846 and then transplanted into recipient mice. After 40 μM EHT1846 treatment, no engraftment of AML cells in recipient mice was observed. Kaplan-Meier analyses indicate that treatment with EHT1846 significantly prolongs survival of the transplanted mice. 20μM dose of EHT1846 was less effective. These data indicated that active Rac1 might be an important contributing factor to leukemogenesis. In addition, short-term homing assays showed that EHT 1846 treatment causes a marked inhibition of AML cell homing into both bone marrow and spleen as compared with controls, indicating that Rac1 mediated homing could be an important step and participated in the leukemogensis. Altogether, our data suggest that activation of Rac1 GTPase is critical for the interaction between HSCs with BM niche and even be contributed to leukemia development. Disclosures Wang: Novartis: Consultancy; Bristol Myers Squibb: Consultancy.

A leukemic stem cell with intrinsic drug efflux capacity in acute myeloid leukemia

Blood ◽  
2001 ◽  
Vol 98 (4) ◽  
pp. 1166-1173 ◽  
Author(s):  
Gerald G. Wulf ◽  
Rui-Yu Wang ◽  
Ingrid Kuehnle ◽  
Douglas Weidner ◽  
Frank Marini ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Myeloid Leukemia ◽  
Side Population ◽  
Fluorescence Emission ◽  
Drug Efflux ◽  
Hematopoietic Stem ◽  
Immunodeficient Mice ◽  
Acute Myeloid

The hematopoietic stem cell underlying acute myeloid leukemia (AML) is controversial. Flow cytometry and the DNA-binding dye Hoechst 33342 were previously used to identify a distinct subset of murine hematopoietic stem cells, termed the side population (SP), which rapidly expels Hoechst dye and can reconstitute the bone marrow of lethally irradiated mice. Here, the prevalence and pathogenic role of SP cells in human AML were investigated. Such cells were found in the bone marrow of more than 80% of 61 patients and had a predominant CD34low/− immunophenotype. Importantly, they carried cytogenetic markers of AML in all 11 cases of active disease examined and in 2 out of 5 cases in complete hematological remission. Comparison of daunorubicin and mitoxantrone fluorescence emission profiles revealed significantly higher drug efflux from leukemic SP cells than from non-SP cells. Three of 28 SP cell transplants generated overt AML-like disease in nonobese diabetic–severe combined immunodeficient mice. Low but persistent numbers of leukemic SP cells were detected by molecular and immunological assays in half of the remaining mice. Taken together, these findings indicate that SP cells are frequently involved in human AML and may be a target for leukemic transformation. They also suggest a mechanism by which SP cells could escape the effects of cytostatic drugs and might eventually contribute to leukemia relapse.

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 Acute myeloid leukemia–induced remodeling of the human bone marrow niche predicts clinical outcome

2020 ◽  
Vol 4 (20) ◽  
pp. 5257-5268
Author(s):  
Yiyang Chen ◽  
Lina Marie Hoffmeister ◽  
Yasmin Zaun ◽  
Lucas Arnold ◽  
Kurt Werner Schmid ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Survival Rate ◽  
Clinical Outcome ◽  
Myeloid Leukemia ◽  
Bone Marrow Niche ◽  
Dependent Manner ◽  
Hematopoietic Stem ◽  
Acute Myeloid ◽  
First Diagnosis

Abstract Murine models of myeloid neoplasia show how leukemia infiltration alters the hematopoietic stem cell (HSC) niche to reinforce malignancy at the expense of healthy hematopoiesis. However, little is known about the bone marrow architecture in humans and its impact on clinical outcome. Here, we dissect the bone marrow niche in patients with acute myeloid leukemia (AML) at first diagnosis. We combined immunohistochemical stainings with global gene expression analyses from these AML patients and correlated them with clinical features. Mesenchymal stem and progenitor cells (MSPCs) lost quiescence and significantly expanded in the bone marrow of AML patients. Strikingly, their HSC- and niche-regulating capacities were impaired with significant inhibition of osteogenesis and bone formation in a cell contact–dependent manner through inhibition of cytoplasmic β-catenin. Assessment of bone metabolism by quantifying peripheral blood osteocalcin levels revealed 30% lower expression in AML patients at first diagnosis than in non-leukemic donors. Furthermore, patients with osteocalcin levels ≤11 ng/mL showed inferior overall survival with a 1-year survival rate of 38.7% whereas patients with higher osteocalcin levels reached a survival rate of 66.8%. These novel insights into the human AML bone marrow microenvironment help translate findings from preclinical models and detect new targets which might pave the way for niche-targeted therapies in AML patients.

scholarly journals Grb10 Is a Tumor Suppressor in Human Acute Myeloid Leukemia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1344-1344
Author(s):  
Wanxing Chai-Ho ◽  
Martina M Roos ◽  
Michelle Li ◽  
Pang Amara ◽  
Yurun Zhang ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Tumor Suppressor ◽  
Myeloid Leukemia ◽  
Negative Regulator ◽  
Leukemia Cells ◽  
Maternal Allele ◽  
Hematopoietic Stem ◽  
Colony Forming Capacity ◽  
Acute Myeloid

Abstract Acute myeloid leukemia (AML) is a common and potentially fatal hematologic malignancy. Allogeneic stem cell transplantation is the only curative therapy for most subtypes of AML, but carries a significant risk of transplant-related mortality. The development of novel therapies to eradicate AML remains a substantial area of unmet medical need. Growth factor receptor bound protein 10 (Grb10) is a member of the family of imprinted genes. Our laboratory demonstrated that in normal hematopoietic system, deletion of the maternal allele of Grb10 significantly increased hematopoietic stem cell long-term repopulating capacity (Yan et al. Cell Rep 2016). Grb10 has been shown to bind the intracellular domain of various tyrosine kinase receptors, e.g. KIT, FLT3 and RET, as well as low-density lipoprotein receptor-related protein 6, a negative regulator of the Wnt/β-catenin pathway. Analyzing RNAseq data from the Leucegene Project, we found that Grb10 is expressed on the majority of patient AML samples regardless of leukemia mutation profile. Silencing of Grb10 expression via Grb10 shRNA increased the proliferation and colony forming capacity of human AML cell lines, Kasumi-1, THP-1 and OCI-AML3 in vitro (p<0.0001 and p<0.01). Conversely, overexpression of Grb10 suppressed human AML cell growth (p<0.05). In order to determine the role of Grb10 in regulating AML growth in vivo, we transduced bone marrow lineage negative cells from mice with Grb10 maternal allele deletion (Grb10 m/+) and wild type (Grb10 +/+) mice with HoxA9-Meis1-neo-MSCV (gift from G. Savageau) and transplanted the progeny into congenic mice. Primary and secondary mice transplanted with Grb10m/+ HoxA9-Meis1 leukemia cells displayed significantly decreased survival compared to mice transplanted with Grb10+/+ HoxA9-Meis1 cells (p<0.001 and p<0.05). Furthermore, leukemia cells with Grb10 maternal allele deletion displayed an increase cell cycle progression and increased leukemia colony forming capacity. RNAseq analysis of Grb10 m/+ leukemia cells from diseased mice revealed significant dysregulation of the canonical Wnt/β catenin signaling pathway compared to Grb10 +/+ mice. RT-qPCR analysis confirmed that Wnt/β-catenin target genes, including MYC, CCND1, and SOX2 were significantly up-regulated in Grb10 knockdown human AML cells lines. Taken together, these data suggest that Grb10 is a powerful tumor suppressor in human AML, and represents a novel mechanistic target for the development of new therapies for human AML. Disclosures No relevant conflicts of interest to declare.

scholarly journals Targeting Interleukin-2 to the Bone Marrow Stroma for Therapy of Acute Myeloid Leukemia Relapsing after Allogeneic Hematopoietic Stem Cell Transplantation

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 980-980
Author(s):  
Christoph Schliemann ◽  
Katrin Gutbrodt ◽  
Andrea Kerkhoff ◽  
Michele Pohlen ◽  
Stefanie Wiebe ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Stem Cell Transplantation ◽  
Cell Transplantation ◽  
Myeloid Leukemia ◽  
Interleukin 2 ◽  
The Other ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Abstract The tumor-directed delivery of therapeutics using monoclonal antibodies specific to a tumor-associated antigen promises to accumulate large doses of the delivered payload at the tumor site while sparing healthy organs. The antibody-based delivery of interleukin-2 (IL-2) to extracellular targets expressed in the easily accessible tumor vasculature has shown promising results in animal models of solid tumors and hematological malignancies. In xenograft and immunocompetent murine models of acute myeloid leukemia (AML), IL-2-based vascular targeting antibody fusions have recently demonstrated potent anti-leukemic activity, especially when used in combination with cytarabine. Here, we report our experiences in four patients with relapsed AML after allogeneic hematopoietic stem cell transplantation (allo-HSCT), who were treated with the immunocytokine F16-IL2, consisting of a human monoclonal antibody specific to spliced large isoforms of tenascin-C fused to human IL-2, in combination with very low dose cytarabine (5 mg subcutaneously twice daily for 10 days). Clinical evidence of anti-leukemia efficacy was shown in all patients. One patient with rapidly progressing disseminated extramedullary AML lesions achieved a complete metabolic response in PET/CT, which lasted three months. Two out of three patients with bone marrow relapse achieved a blast reduction with transient molecular negativity (NPM1). One of the two enjoyed a short complete remission before AML relapse occurred two months after the first infusion of F16-IL2. The other patient did not regenerate neutrophil and thrombocyte counts and showed progressive disease after completion of the first cycle. In line with a site-directed delivery of the cytokine, F16-IL2 led to an extensive infiltration of immune effector cells (natural killer cells, CD8+ T cells, γδ T cells) in the bone marrow. Grade 2 fevers were the only non-hematological side effects in two patients. Grade 3 cytokine-release syndrome developed in the other two patients, required hospitalization, but was manageable in both cases with systemic glucocorticoids. No non-hematological grade 4 toxicities were observed. The concept of specifically targeting IL-2 to the leukemia-associated stroma using armed antibodies deserves further evaluation in clinical trials, especially in patients who relapse after allo-HSCT. Disclosures Off Label Use: In this report, the antibody-cytokine fusion protein F16-IL2 has been used in a compassionate use setting in individual patients presenting with AML relapse after allogeneic stem cell transplantation. F16-IL2 is currently being evaluated in phase I/II studies in patients with solid cancer.. Neri:Philogen SpA: Employment, Equity Ownership.

scholarly journals CXCR4 Antagonists as Stem Cell Mobilizers and Therapy Sensitizers for Acute Myeloid Leukemia and Glioblastoma?

Biology ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 31 ◽  
Author(s):  
Vashendriya V.V. Hira ◽  
Cornelis J.F. Van Noorden ◽  
Remco J. Molenaar
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Myeloid Leukemia ◽  
Patient Survival ◽  
Hematopoietic Stem ◽  
Poor Patient ◽  
Acute Myeloid ◽  
Poor Patient Survival

Glioblastoma is the most aggressive and malignant primary brain tumor in adults and has a poor patient survival of only 20 months after diagnosis. This poor patient survival is at least partly caused by glioblastoma stem cells (GSCs), which are slowly-dividing and therefore therapy-resistant. GSCs are localized in protective hypoxic peri-arteriolar niches where these aforementioned stemness properties are maintained. We previously showed that hypoxic peri-arteriolar GSC niches in human glioblastoma are functionally similar to hypoxic peri-arteriolar hematopoietic stem cell (HSC) niches in human bone marrow. GSCs and HSCs express the receptor C-X-C receptor type 4 (CXCR4), which binds to the chemoattractant stromal-derived factor-1α (SDF-1α), which is highly expressed in GSC niches in glioblastoma and HSC niches in bone marrow. This receptor–ligand interaction retains the GSCs/HSCs in their niches and thereby maintains their slowly-dividing state. In acute myeloid leukemia (AML), leukemic cells use the SDF-1α–CXCR4 interaction to migrate to HSC niches and become slowly-dividing and therapy-resistant leukemic stem cells (LSCs). In this communication, we aim to elucidate how disruption of the SDF-1α–CXCR4 interaction using the FDA-approved CXCR4 inhibitor plerixafor (AMD3100) may be used to force slowly-dividing cancer stem cells out of their niches in glioblastoma and AML. Ultimately, this strategy aims to induce GSC and LSC differentiation and their sensitization to therapy.

scholarly journals Allogeneic Hematopoietic Stem Cell Transplantation for Children and Adolescents with Acute Myeloid Leukemia in Brazil: A Multicentric Retrospective Study

2020 ◽  
Vol 29 ◽  
pp. 096368972094917
Author(s):  
Ana Luiza de Melo Rodrigues ◽  
Carmem Bonfim ◽  
Adriana Seber ◽  
Vergilio Antonio Rensi Colturato ◽  
Victor Gottardello Zecchin ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Hematopoietic Stem Cell ◽  
Myeloid Leukemia ◽  
Survival Rates ◽  
Progression Free Survival ◽  
Cell Transplant ◽  
Hematopoietic Stem ◽  
Acute Myeloid

The survival rates of children with high-risk acute myeloid leukemia (AML) treated with hematopoietic stem cell transplant (HSCT) range from 60% to 70% in high-income countries. The corresponding rate for Brazilian children with AML who undergo HSCT is unknown. We conducted a retrospective analysis of 114 children with AML who underwent HSCT between 2008 and 2012 at institutions participating in the Brazilian Pediatric Bone Marrow Transplant Working Group. At transplant, 38% of the children were in first complete remission (CR1), 37% were in CR2, and 25% were in CR3+ or had persistent disease. The donors included 49 matched-related, 59 matched-unrelated, and six haploidentical donors. The most frequent source of cells was bone marrow (69%), followed by the umbilical cord (19%) and peripheral blood (12%). The 4-year overall survival was 47% (95% confidence interval [CI] 30%–57%), and the 4-year progression-free survival was 40% (95% CI 30%–49%). Relapse occurred in 49 patients, at a median of 122 days after HSCT. There were 65 deaths: 40 related to AML, 19 to infection, and six to graft versus host disease. In conclusion, our study suggests that HSCT outcomes for children with AML in CR1 or CR2 are acceptable and that this should be considered in the overall treatment planning for children with AML in Brazil. Therapeutic standardization through the adoption of multicentric protocols and appropriate supportive care treatment will have a significant impact on the results of HSCT for AML in Brazil and possibly in other countries with limited resources.

Acute Myeloid Leukemia Cells Acquire Stem Cell Features in the Bone Marrow Microenvironment

2014 ◽  
Vol 14 ◽  
pp. S119-S120
Author(s):  
V. Lokesh Battula ◽  
Juliana Benito ◽  
Anitha G. Somanchi ◽  
Seshagiri Duvvuri ◽  
Lauren Hodgson ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Myeloid Leukemia ◽  
Bone Marrow Microenvironment ◽  
Leukemia Cells ◽  
Acute Myeloid Leukemia Cells ◽  
Acute Myeloid

scholarly journals Acute Myeloid Leukemia-Derived Exosomes Transform Bone Marrow Niche into Leukemic Niche.

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 352-352
Author(s):  
Bijender Kumar ◽  
Mayra Garcia ◽  
Lihong Weng ◽  
Xiaoman Lewis ◽  
Jodi Murakami ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Conflicts Of Interest ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Bone Marrow Niche ◽  
Stromal Compartment ◽  
Bm Niche ◽  
Acute Myeloid

Abstract Increasing evidence suggests that leukemia cells take shelter in the bone marrow (BM) niche, where they hide from chemotherapy and continue to divide. As yet, how leukemia cells alter the BM niche to facilitate their growth and assist them in evading chemotherapy is unclear. In this study, we provide compelling evidences that acute myeloid leukemia (AML), through exosome secretion, transformed the BM niche to facilitate their own growth and suppress normal hematopoiesis. Using AML xenograft and MLL-AF9 knock-in mouse model, we show that leukemia cells as well as AML-derived exosomes stimulate the growth of BM stromal progenitors and blocked the osteolineage development in our stromal compartment analysis. Histological analysis and micro-CT examination confirmed loss or thinning of the bone in both leukemia and leukemic exosome-treated animals. Expression of cell adhesion molecules (NCAM1, VCAM1, CD44, OPN & ICAM1) and factors important for angiogenesis (Angpt1, Angpt2 and VEGF) are upregulated, whereas genes important for HSC maintenance (CXCL12 and SCF), osteoblast (OCN, OSX, Notch3 and IGF1) and chondrocyte (ACAN, SOX9) development are suppressed. While we observed increases in phenotypic LT-HSC in AML-derived exosomes treated mice, these mice show reduced multilineage reconstitution ability, increased cell cycle entry and higher sensitivity to myeloablative stress suggesting that HSCs from exosome-treated mice have lower stem cell activity than their counterparts from normal mice.In addition, leukemia-modified stroma cells exhibit marked reduction in ability to support normal HSCs. Pre-treatment of AML-derived exosome “prime” the animal for leukemia cell invasion and accelerate leukemia progression. Conversely,disruption of exosome secretion by targeting Rab27a in AML cells significantly delays leukemia progression. These data strongly support the notion that leukemia-modified niches favor leukemic cell proliferation and suppress normal hematopoiesis. Disclosures No relevant conflicts of interest to declare.

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