scholarly journals Ginsenoside Rh2 Mitigates Pediatric Leukemia Through Suppression of Bcl-2 in Leukemia Cells

2015 ◽  
Vol 37 (2) ◽  
pp. 641-650 ◽  
Author(s):  
Xiaoru Wang ◽  
Yulin Wang
Keyword(s):  
Cell Lines ◽  
Marrow Cell ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Luciferase Reporter ◽  
Therapeutic Effects ◽  
Ginsenoside Rh2 ◽  
Pediatric Leukemia ◽  
Leukemia Cell Lines

Background/Aims: Acute myeloid leukemia (AML) is a severe malignant cancer worldwide, in both adult and pediatric patients. Since bone marrow cell transplantation is seriously limited by the availability of the immune-paired donor sources, the therapy for pediatric leukemia remains challenging. Ginsenoside Rh2 (GRh2) is a well-characterized component in red ginseng, and has established therapeutic effects for different diseases, although whether GRh2 may have a therapeutic effect on pediatric leukemia has not been investigated. Methods: We examined the effects of GRh2 on the survival of mice in an acute leukemia model. We analyzed the effects of GRh2 on the cell viability of leukemia cell lines in vitro, using a CCK-8 assay and an MTT assay. We analyzed the effects of GRh2 on the apoptosis of leukemia cell lines in vitro, by flow cytometry. We analyzed the levels of Bcl-2 and microRNA-21 (miR-21) in GRh2-treated leukemia cells. Prediction of binding between miR-21 and 3'-UTR of Bcl-2 mRNA was performed by a bioinformatics algorithm and confirmed by a dual luciferase reporter assay. Results: GRh2 significantly prolonged the survival of mice with pediatric leukemia. GRh2 significantly decreased the viability of leukemia cells in vitro, through induction of apoptosis. GRh2 significantly decreased the levels of an anti-apoptotic protein Bcl-2 in leukemia cells, possibly through induction of miR-21, which suppressed the translation of Bcl-2 mRNA via 3'-UTR binding. Conclusion: GRh2 may be an effective treatment for pediatric leukemia, and GRh2 may induce apoptosis of leukemia cells through miR-21-modulated suppression of Bcl-2.

Preclinical Evaluation of Oncolytic Reovirus in Targeted Therapeutics for High-Risk Pediatric Leukemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3571-3571
Author(s):  
Matthew F. Clarkson ◽  
Aru Narendran ◽  
Randal N. Johnston
Keyword(s):  
Cell Death ◽  
High Risk ◽  
Cell Viability ◽  
Cell Lines ◽  
Leukemia Cell ◽  
Treatment Strategies ◽  
Leukemia Cells ◽  
Western Blots ◽  
Pediatric Leukemia ◽  
Leukemia Cell Lines

Abstract Abstract 3571 Purpose: Leukemia is the most common malignancy in children. Improved treatment strategies in recent decades have yielded substantially enhanced outcomes for children with leukemia, reaching survival rates >80%. However, there remain significant issues with current treatment. Certain subgroups of patients who are resistant to or relapse from current treatments have a dismal prognosis. Furthermore, there are significant late effects of intensive treatments, including secondary cancers, neurocognitive defects, cardiotoxicity, obesity and infertility. For these reasons, novel treatment strategies are urgently needed for high-risk leukemia in children. Reovirus type 3 Dearing is a wild-type double-stranded RNA virus that has shown great promise as a selective oncolytic agent by its ability to replicate in transformed cells but not in normal cells. Although a number of early phase clinical studies have been completed in patients with advanced, refractory solid tumors in adults, systematic evaluation of this agent in the treatment of refractory pediatric leukemia has not been reported. As an initial step towards developing an oncolytics based treatment approach, we report preclinical data with respect to the activity, target validation, target modulation and drug combinability of reovirus in childhood leukemia cells. Experimental Design: A panel of pediatric leukemia cell lines representing high-risk molecular features such as Bcr-Abl, MLL rearranged and mixed lineage was used (n =6). Expression of JAM-A, the cell surface receptor for reovirus, was assessed by flow cytometry. The Ras Activation Assay Kit (EMD Millipore) was used to assess activity of the RAS protein. Western Blots were used to assess the activation (phosphorylation) of the signaling partners downstream of RAS. Cells treated with reovirus, chemotherapy drugs, or both for distinct treatment schedules were assessed for cell viability by the CellTiter-Glo© Luminescent Cell Viability Assay (Promega), and cell death by apoptosis was confirmed by cleavage of PARP. Productive viral infection was assessed by measuring reoviral protein synthesis by Western Blots, and reoviral replication was assessed by virus plaque titration assay. Drug synergies were calculated according to the method of Chou and Talalay. Results: Target validation assays showed the expression of JAM-A, which facilitates effective viral entry into malignant cells, in five of six cell lines. These cell lines also demonstrated differential activation of RAS and downstream kinases, suggesting targeted susceptibility of these cells to reovirus oncolysis. To further test this, we infected cells with reovirus for 1–4 days and assessed cytopathic effects. Using phase contrast microscopy, we observed the virus treated cell lines to demonstrate morphological changes characteristic of cell death following infection. Cell viability assays were used to quantify this effect, and the mechanism of cell death was determined to be apoptotic as evidenced by caspase-dependent cleavage of PARP. Reovirus-induced cell death was correlated with viral protein production and replication. Next, we screened for the ability of reovirus to induce synergistic activity in a panel of conventional and novel targeted therapeutic agents. Our studies showed that, in contrast to the current antileukemic agents, the Bcl-2 inhibitor BH3 mimetic ABT-737 was able to significantly synergize with reovirus in all cell lines tested. Conclusions: In our in vitro studies, oncolytic reovirus as a single agent showed potent oncolytic activity against all pediatric leukemia cell lines tested that express the receptor for reovirus, regardless of the status of the RAS signaling pathway. Further, we found reovirus-induced oncolysis can be enhanced by combination with Bcl-2 inhibition but was unaltered or antagonized by the other drugs indicating a key relationship between the two pathways. As such, our data for the first time, show that pediatric leukemia cells carry the potential to be targeted by reovirus induced oncolysis and the identification of drug synergy and the biomarkers of target modulation provide the basis for further studies to develop this novel therapeutic approach for clinical studies in the near future. Disclosures: No relevant conflicts of interest to declare.

The CXCR4 Antagonist AMD3100 Has Dual Effects, Initially Enhancing and Later Inhibiting Survival and Proliferation, in Myeloid Leukemia Cells in Vitro.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1721-1721
Author(s):  
Ha-Yon Kim ◽  
Ji-Young Hwang ◽  
Seong-Woo Kim ◽  
Gak-Won Yun ◽  
Young-Joon Yang ◽  
...  
Keyword(s):  
Cell Lines ◽  
Myeloid Leukemia ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Dependent Manner ◽  
Cxcr4 Antagonist ◽  
Hematopoietic Stem ◽  
Leukemia Cell Lines ◽  
Number Of Cells

Abstract Abstract 1721 Poster Board I-747 AMD3100, a small bicyclam antagonist for chemokine receptor CXCR4, induces the peripheral mobilization of hematopoietic stem cells. It also induces the segregation of leukemia cells in the bone marrow microenvironment, which should enhance the chemosensitivity of the cells. Based on these observations, AMD3100 is being considered for clinical use. However, AMD3100 activates G-protein coupled with CXCR4 and acts as a partial CXCR4 agonist. In this study, we explored whether AMD3100 affects the proliferation and survival of myeloid leukemia cells. As demonstrated previously, both AMD3100 and T140, another CXCR4 antagonist, markedly inhibited stromal cell-derived factor-1 (SDF-1)-induced chemotaxis and induced the internalization of CXCR4 in myeloid leukemia cell lines (U937, HL-60, MO7e, KG1a, and K562 cells) and CD34+ primary human acute myeloid leukemia (AML) cells. SDF-1 alone did not stimulate the proliferation of these leukemia cells, nor did it rescue the cells from apoptosis induced by serum deprivation. By contrast, AMD3100, but not T140, stimulated the proliferation of all five leukemia cell lines and primary AML cells in a dose-dependent manner in serum-free conditions for up to 5 days (∼ 2-fold increases at a concentration of 10-5M), which was abrogated by pretreating the cells with pertussis toxin. AMD3100 binds to CXCR7, another SDF-1 receptor, and all of the cells examined in this study expressed CXCR4 on the cell surface to some extent. The proliferation-enhancing effects of AMD3100 were not changed by knocking-down CXCR7 using the siRNA technique, whereas knocking-down CXCR4 significantly delayed the enhanced proliferation induced by AMD3100. Neither AMD3100 nor T140 induced the phosphorylation of Akt, Stat3, MAPK p44/p42, or MAPK p38, which are involved in SDF-1 signaling. In extended cultures of these cells for up to 14 days, AMD3100, but not T140, induced a marked decrease in the number of cells, compared to the control, after incubation for 5-7 days. Adding SDF-1 at the beginning and middle of the incubation did not affect the early increase or later decrease in the number of cells. AMD3100 reduced the apoptosis of these cells to a modest degree over the first 5-7 days and then markedly increased it. Consistent with the proliferation assay, AMD3100 increased the number of leukemia cell colonies during the early period of the assay, while it markedly decreased the number and size of the colonies in the later period of the assay. In conclusion, AMD3100 exerts dual effects, initially enhancing and subsequently inhibiting the survival and proliferation, in myeloid leukemia cells in vitro. Disclosures No relevant conflicts of interest to declare.

The Novel Sulfonamidebenzamide ML291 Activates Apoptotic UPR Signaling in Pediatric Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3523-3523
Author(s):  
Danielle Garshott ◽  
Nicole Melong ◽  
Tania T. Sarker ◽  
Yue Xi ◽  
Amy Brownell ◽  
...  
Keyword(s):  
Cell Lines ◽  
Leukemia Cell ◽  
Leukemic Cell ◽  
K562 Cells ◽  
Leukemia Cells ◽  
Wild Type ◽  
Leukemia Cell Lines ◽  
Proliferation Assays

Abstract Background: Acute leukemias are the most common cancers in childhood. Despite multi-agent chemotherapy protocols and the introduction of novel molecularly targeted therapies which have resulted in improved survival over the last few decades, relapsed acute lymphoblastic leukemia remains the second most common pediatric cancer diagnosis. In addition, morbidities from current chemotherapy regimens are unacceptably high. Abundant evidence point to a major role for mediators of the unfolded protein response (UPR) in normal and leukemic white blood cell biology. We have demonstrated that activation of the UPR is a productive approach to inhibit the proliferation of solid tumor cell lines in vitro and to reducing xenograft burden in vivo. The UPR consists of genetically distinct mechanisms that serve to clear misfolded proteins from the endoplasmic reticulum (ER) and enhance protein folding, or induce apoptosis if the initiating stress is prolonged or robust. ML291 is a novel UPR-inducing sulfonamidebenzamide, identified through cell-based high throughput screening and iterative SAR-guided chemical synthesis, that overwhelms the adaptive capacity of the UPR and induces apoptosis in a variety of solid cancer models. Objective: To determine the ability of ML291 to activate the UPR and induce apoptosis in a panel of leukemia cell lines, and to use CHOP-null K562 cells to elucidate the relative contribution of the UPR. We hypothesized that ML291 might activate the PERK/eIF2a/CHOP (apoptotic) arm of the UPR and reduce leukemic cell burden in vitro and in vivo. Methods: MTT and luciferase-based proliferation assays, flow cytometry and RT-qPCR were used to evaluate cell growth, UPR activation and apoptosis in a panel of leukemia cell lines that included AML, ALL and CML in cells exposed to ML291. CRISPR-Cas9 genome editing was used to delete CHOP in K562 (human myeloid leukemia) cells. Deletion was validated by immunoblot analysis and these cells were subjected to the same proliferation and gene analyses described above. The in vivo response to ML291 therapy was evaluated in an established zebrafish xenograft assay (Corkery et al. BJH 2011) in which embryos were xenotransplanted with wild type or CHOP knockdown K562 cells and embryos bathed in ML291. Results: Immunoblot and RT-qPCR analysis revealed an accumulation of proteins and increased gene expression for downstream UPR genes, including CHOP, GRP78/BiP, GADD34 and XBP1 in leukemia cells following ML291 treatment, indicating the activation of the UPR. Increased expression of the apoptotic genes, NOXA, PUMA and DR5 was also observed post-treatment with ML291; and dose response proliferation assays performed after 24 hours revealed IC50 concentrations of 1 - 30µM across cell lines. CHOP deleted K562 cells were protected from cell death when cultured with increasing concentrations of ML291, and were significantly less able to translocate phosphatidylserine across the cell membrane and activate the caspase cascade. When zebrafish embryos xenotransplanted with K562-wild type or -CHOP-null cells were bathed in water containing 5mM ML291 for three days, there was a significant reduction in leukemia cell burden exclusively in theK562 wild type xenografts. Conclusion: Collectively these data indicate that intact PERK/eIF2a/CHOP signaling is required for efficient leukemic cell apoptosis in response to ML291 in vitro and in vivo, and support the hypothesis that small molecule enforcement of the UPR might be a productive therapeutic approach in leukemia. Disclosures No relevant conflicts of interest to declare.

A-Type Proanthocyanidins Prevent Engraftment Of Primary Acute Myelogenous Leukemia Cells In Mice and Exhibit Potentially Novel Anti-Leukemia Mechanisms

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3962-3962
Author(s):  
Laura M Bystrom ◽  
Hongliang Zong ◽  
Hsiao-Ting Hsu ◽  
Neng Yang ◽  
Noa Greenberg ◽  
...  
Keyword(s):  
Cell Lines ◽  
Iron Metabolism ◽  
Leukemia Cell ◽  
Myelogenous Leukemia ◽  
Leukemia Cells ◽  
Survival Pathways ◽  
Leukemia Cell Lines ◽  
Acute Myelogenous

Abstract Acute myelogenous leukemia (AML) is often a fatal disease where after strong induction therapy most patients relapse and die. AML originates and is maintained by leukemia stem cells (LSCs). Failure to eliminate LSCs by chemotherapy is likely to result in disease relapse. Therefore, it is a priority to identify new therapies that eliminate blasts while ablating LSCs and preventing a relapse. We have found that a unique class of compounds in cranberries (Vaccinium macrocarponAit.), known as A-type proanthocyanidins (A-PACs), were effective against several leukemia cell lines and primary AML samples in vitro. A-PACs consist of monomeric epicatechin units attached to one another by a carbon-carbon bond and a distinctive ether bond that differentiates these compounds from other proanthocyanidins found in nature. Moreover, A-PACs possess ortho-hydroxyl phenolic groups that have the potential to bind to iron and alter redox status. Preliminary work showed that pre-treatment with antioxidants or holo-transferrin (iron-saturated transferrin) partially protected AML cells from A-PAC induced cell death (p<0.01). A-PACs were also found to selectively ablate leukemia stem and progenitor cells, with minimal effects on normal hematopoetic stem cells. Furthermore, AML engraftment of cells treated ex vivo with 62.5 µg/ml A-PACs was decreased (90.6%, n=3, p<0.001), while normal CD34+ cells retained engraftment capability in immunodeficient mice. It was also found that a fraction of A-PACs of up to 7 degree of polymerization was more effective than individual A-PACs. This information prompted us to investigate the in vivo anti-leukemia effects of A-PACs in xenotransplanted mice with primary AML samples, and to further investigate the mechanisms associated with these compounds. Primary AML cells were injected in sub-lethally irradiated NOD/SCID mice. Four weeks after injections, when human leukemia cells have engrafted, intraperitoneal injections of cytarabine (AraC) at 60 mg/kg were given to the mice for 1 week everyday or A-PACs (100 mg/kg dose every 3 days for A-PACs) and vehicle control (1% DMSO in PBS every 3 days) were injected for 2.5 weeks. Mice were sacrificed and leukemia engraftment evaluated using anti-human CD45 and CD33. Moreover, primary cells treated with A-PACs were assessed for effects on iron metabolism, ROS, and survival pathways either by gene expression analysis, flow cytometry or mass spectrometry. Administration of A-PACs to NOD-SCID mice bearing AML tumors reduced tumor burden. Mice that were treated with the vehicle control had engraftment of AML primary cells equivalent to 16.1% (95% CI: -6.0, 38.37; n=4), whereas the mice treated with the A-PACs and AraC showed a level of engraftment of 4.9% (95% CI: 2, 8; n=5) and 5.8% (95% CI: -1.1, 12.7; n=5), respectively. No significant changes in hemoglobin or weight were found between the different treatment groups. Moreover, qPCR analysis of sensitive leukemia cell lines treated with A-PACs showed changes in gene expression of several iron metabolism genes in sensitive leukemia cell lines (up-regulation of ferritin and transferrin receptors 1 and down-regulation of ferroportin) and several ROS-relevant genes (down-regulation of nuclear factor erythroid-2-related factor 2 and glutamate-cysteine ligase regulatory subunit). Mass spectrometry also confirmed that A-PACs bind iron. The results indicate that A-PACs not only target primary AML cells in vitro but are also effective in vivo. Secondary transplants are also being performed to determine the effects on LSC activity. Some of the anti-leukemia mechanisms under investigation include effects related to iron metabolism, ROS or inhibition of survival pathways. Understanding the unique structure and biological effects of A-PACs may provide novel information about pathways involved in the survival of LSCs and provide crucial information in preparation for clinical trials and/or optimal combination drug therapies. Disclosures: Rivella: Novartis: Consultancy; Bayer: Consultancy; Isis: Consultancy, Research Funding; Merganser: Equity Ownership, Research Funding; Biomarin: Consultancy; Alexion: Consultancy; Imago: Consultancy.

Mechanisms of Suppressive Effects of MYD88 Inhibitors on the Growth of Lymphoma and Leukemia Cells

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2773-2773
Author(s):  
Erika Shiratori ◽  
Mai Itoh ◽  
Mika Ohtaka ◽  
Shohei Nogami ◽  
Shuji Tohda
Keyword(s):  
Cell Cycle ◽  
Cell Lines ◽  
Leukemia Cell ◽  
Immunoblot Analysis ◽  
Leukemia Cells ◽  
Targeted Drugs ◽  
Leukemia Cell Lines ◽  
Apoptosis Assay ◽  
Daudi Cells

Abstract Introduction : Myeloid differentiation primary response gene 88 (MYD88) is an adaptor protein that binds to the Toll-like/interleukin-1 receptor to form a homodimer and activates NF-kB pathway. Activating MYD88 mutations are found in 90% of lymphoplasmacytic lymphoma (Waldenström's macroglobulinemia) cases and 30% of activated B-cell type diffuse large B-cell lymphoma (DLBCL) cases. To investigate the role of MYD88 in the growth of lymphoma/leukemia cells, with or without MYD88mutations, and to examine whether MYD88 inhibitors can be used as novel molecular-targeted drugs, we studied their effects on the growth of lymphoma and leukemia cells in vitro. Methods : Seven lymphoma/leukemia cell lines (TMD8 derived from DLBCL with MYD88 mutations, Daudi from Burkitt lymphoma, NALM-6 from B-ALL, Jurkat and KOPT-K1 from T-ALL, THP-1 and TMD7 from AML without MYD88 mutations) and normal lymphocytes from healthy volunteers were obtained, following an informed consent. The effect of the MYD88 inhibitor, ST2825, on the in vitro growth of these cell lines was then examined using the WST-8 colorimetric assay. ST2825 is a synthetic peptide-mimetic compound, which inhibits MYD88 dimerization. A Bruton tyrosine kinase (BTK) inhibitor, ibrutinib, was used as the reference inhibitor. The effect of ST2825 on protein expression was examined by immunoblot analysis. Cell cycle analysis and Annexin V apoptosis assay were performed using flow cytometry. To comprehensively screen the changes in mRNA expression after ST2825 treatment, microarray analysis was performed for TMD8 and Jurkat cells. MYD88knockdown experiments using small interfering RNA were also performed. Results : The MYD88 protein was expressed in all cell lines. ST2825 (30 μM) suppressed the growth of all lymphoma/leukemia cell lines, but did not affect the viability of normal lymphocytes. The IC50 for TMD8 cells was similar to that for other cells, such as Daudi cells. Apoptosis assay revealed that ST2825 induces apoptosis in all the cell lines studied. In Daudi cells, ST2825 induced G2/M cell cycle arrest. Immunoblot analysis revealed that ST2825 suppresses the phosphorylation of certain NF-kB signaling components, such as RELA and IkB, in all cell lines. In TMD8, Daudi, and NALM-6 cells, ST2825 suppressed the phosphorylation of BTK, and MYD88 knockdown suppressed the phosphorylation of RELA and BTK. Microarray analysis revealed that ST2825 treatment downregulates the expression of various genes including MYD88, and upregulates the expression of other genes such as NGFR, FOSB, and HSP. Treatment with ibrutinib (1 nM) suppressed the growth of only TMD8 cells. Treatment with ST2825 plus ibrutinib additively suppressed the growth of TMD8 cells. Conclusions : The MYD88 inhibitor ST2825 suppresses the growth of various lymphoma and leukemia cells, suggesting that MYD88 is involved in regulating the growth of these cells; however, the off-target effects of ST2825 should be considered. Further investigation is required to assess the potential of MYD88 inhibitors as novel molecular-targeted drugs against lymphoma and leukemia. Disclosures No relevant conflicts of interest to declare.

Hemangioblastic Activity of Infant Leukemia with t(4;11).

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4279-4279
Author(s):  
Zhongbo Hu ◽  
Xiaomiao Li ◽  
William B. Slayton
Keyword(s):  
Bone Marrow ◽  
Blood Vessels ◽  
Cell Lines ◽  
Leukemia Cell ◽  
Scid Mice ◽  
Leukemia Cells ◽  
Leukemia Cell Lines ◽  
Infant Leukemia

Abstract Background: Infant leukemia patients with t(4;11) have an extremely high risk for treatment failure. Hemangioblasts are cells that were initially described in the embryonic yolk sac, where they make both blood and blood vessels when these two systems are forming. It was demonstrated that hemangioblasts are present in the adult bone marrow and CML patients. Recently, subgroups of infant ALL patients with t(4;11) were found to have gene expression profiles similar to hemangioblasts by microarray. However, whether infant leukemia cells behave like hemangioblasts and produce their own blood vessels remains unknown. Objective: We sought to determine whether infant leukemia cells with t(4;11) are derived from malignant hemangioblasts and can produce their own blood vessels. Design/Methods: Three childhood leukemia cell lines with t(4;11): MV4-11, SEM-K2 and RS4-11, were used to analyze the expression pattern of key angiogenic receptors by flow cytometry and angiogenesis related proteins by protein array in comparison with benign endothelial cells. These cell lines were also cultured in vitro using Matrilgel, an in vitro angiogenesis assay system, in order to test their ability to produce vascular tubes. These cell lines were injected into the immune deficient NOD/SCID mice after sublethal irradiation to establish leukemia in vivo. Some of primary cells from MLL patients were obtained and subcutaneously injected into NOD/SCID mice mixed with BD Matrigel to observe their vessel development in vivo together with these three cell lines. The bone marrow, liver, spleen and tumor tissues together with Matrigel were collected to look for the evidence of t(4;11) in endothelial cells by immunohistochemical staining and fluorescent in situ hybridization (FISH). Results: The leukemia cell lines expressed many angiogenetic cytokines, such as VEGF, VEGF-D, RANTES, PIGF, PDGF-BB, MCP-1, IGF-1, ENA-78, and angiogenin, at the same levels as HUVEC cells, a human umbilical vessel endothelial cell line. Different cell lines expressed some angiogenesis-related receptors, such as CD31, Tie-2, PDGFRalpha, CD141, CD146, and KDR. None of the cell lines formed tubes in Matrigel. When these three cell lines generated leukemia in NOD/SCID mice, the microvessel density level increased in the tumor areas. However, immunostaining for human and murine endothelial markers demonstrated that all the vessels came from the mouse, not from the human leukemia cells. Conclusions: We conclude that infant leukemia cell lines with t(4;11) have proangiogenesic activity. However, these cells do not function as hemangioblasts, as they do not produce blood vessels in culture or in vivo in NOD/SCID mice. We plan to look further by examing bone marrow biopsies from patients with t(4;11) leukemia to determine whether the translocation is present in their blood vessels.

Clathrin Assembly Protein CALM Is Necessary for Leukemia Cell Proliferation and Erythroid Development Via Regulating Transferrin Receptor Endocytosis

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 244-244
Author(s):  
Yuichi Ishikawa ◽  
Manami Maeda ◽  
Min Li ◽  
Sung-Uk Lee ◽  
Julie Teruya Feldstein ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Leukemia Cell Lines ◽  
Erythroid Development

Abstract Abstract 244 Clathrin assembly lymphoid myeloid leukemia (CALM) protein is implicated in clathrin dependent endocytosis (CDE) and the CALM gene is the target of the t(10;11)(p13;q14-21) CALM/AF10 translocation, which is observed in multiple types of acute leukemia. Although the translocation generally dictates poor prognosis, the molecular mechanisms by which the fusion protein exerts its oncogenic activity remains elusive. To determine the role of CALM and CDE in normal hematopoiesis and leukemogenesis, we generated and characterized both conventional (Calm+/−) and conditional (CalmF/FMx1Cre+) Calm knockout (KO) mutants. Furthermore, we determined the impact of Calm loss on leukemia cell growth in vitro and in vivo employing a series of leukemia cell lines and leukemia mouse models. Hematopoietic-specific Calm knockout mice (CalmF/FMx1Cre+) exhibited a hypocromatic anemia with increased serum iron levels. We observed significant reduction in mature erythroblasts/erythrocytes (TER119+CD71-) with concomitant increase in immature erythroblasts (TER119+CD71+) in the spleen of CalmF/FMx1Cre+ mice. The frequencies of erythroblasts in S phase were lower and the proportions of apoptotic (cleaved PARP positive) erythroblasts were increased in CalmF/FMx1Cre+ mice. Surface transferrin receptor 1 (Tfr1, CD71) levels were significantly up-regulated in Calm-deficient hematopoietic progenitors, and uptake of Alexa647-conjugated transferrin was abrogated in Calm-deficient erythroblasts, revealed by immunofluorescence analysis. Freez-etch electron microscopy analysis showed a defective clathrin coated vesicle (CCV) formation in Calm-deficient erythroblasts, indicating that Calm is indispensable for iron-bound transferrin internalization by regulating CCV formation, thereby critical for erythroid differentiation and hemoglobinization. CALM was highly expressed in leukemia/lymphoma cell lines and primary acute myeloid leukemia samples, although its expression was limited to erythroblasts in normal hematopoietic lineage cells. Treatment of leukemia cell lines with Desferoxamine (DFO), an iron chelator, led to a significant increase in Calm mRNA levels, suggesting that Calm expression is regulated by intracellular iron levels. Since highly proliferative leukemia cells demand iron as a cofactor for ribonucleotide reductase (RNR), we hypothesized that Calm is required for leukemia cell proliferation by regulating iron-bound transferrin internalization. To determine the effect of Calm inactivation in leukemia cells, we transduced a series of leukemia cell lines with a lentivirus-based ShRNA vector (pLKO-GFP), which allowed shRNA-expressing cells to be traced by green fluorescent protein (GFP). Calm shRNA transduced cells, but not cells transduced with scrambled shRNA, showed a proliferative disadvantage compared to non-transduced cells. To determine the effect of Calm deletion in leukemia cells in vivo, the CALM/AF10 oncogene was retrovirally transduced into either wild type (WT) or CalmF/FMx1Cre+ bone marrow (BM) cells and the cells were subsequently transferred to lethally-irradiated recipient mice. The Calm gene was deleted in donor cells via pIpC injections one month after transplant (before leukemia development) and survival curves generated. The recipients transplanted with the BM cells from CalmF/FMx1Cre+ mice showed a significantly delayed onset of leukemia and longer survivals compared to control (p=0.001), indicating that Calm is necessary for the development of CALM/AF10-induced leukemia. We next assessed whether Calm is required for the “maintenance” of leukemia in vivo. Leukemia cells were harvested from the primary recipients transplanted with the CALM/AF10-transduced CalmF/FMx1Cre+ BM cells (in which the endogenous Calm genes were intact) and transferred to the secondary recipients. The leukemic secondary recipient mice were then injected with pIpC and survival curves generated. Calm inactivation significantly delayed leukemia progression by blocking leukemia cell proliferation. Taken together, our data indicate that Calm is essential for erythroid development and leukemia cell proliferation by regulating TFR1 internalization. Since Calm inactivation significantly blocked the leukemia cell proliferation in vitro and in vivo, our findings may provide new therapeutic strategies for acute myeloid leukemia. Disclosures: Naoe: Kyowa-Hakko Kirin.: Research Funding; Dainipponn-Sumitomo Pharma.: Research Funding; Chugai Pharma.: Research Funding; Novartis Pharma.: Honoraria, Speakers Bureau; Zenyaku-Kogyo: Research Funding; Otsuka Pharma.: Research Funding.

scholarly journals Identification of GPAT1 As a Novel Therapeutic Target for Acute Leukemia By Inhibiting Leukemia Specific Metabolism

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1384-1384
Author(s):  
Hidetoshi Irifune ◽  
Yu Kochi ◽  
Masayasu Hayashi ◽  
Yoshikane Kikushige ◽  
Toshihiro Miyamoto ◽  
...  
Keyword(s):  
Acute Leukemia ◽  
Cell Lines ◽  
Mass Spectrometer ◽  
Mitochondrial Function ◽  
Therapeutic Target ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Leukemia Cell Lines

With the development of mass spectrometer technology, recent studies revealed the critical roles of cancer-specific metabolism for tumor propagation in several types of cancers. In leukemia, many studies have been conducted to elucidate a leukemia-specific metabolism, and several effective treatments such as IDH1/2 inhibitors targeting acute myeloid leukemia (AML) with IDH1/2 mutation have been developed. To identify the new metabolic pathways on which acute leukemia cells depend, we purified water-soluble metabolites from CD34+ hematopoietic stem and progenitor cells (HSPCs) of healthy donors, AML and acute lymphoblastic leukemia (ALL) patients, and we comprehensively measured 116 metabolites using mass spectrometer analysis. From this experiment, we found that the cellular content of glycerol 3-phosphate (G3P) in CD34+ AML and ALL cells was lower than that of normal CD34+ HSPCs. G3P is an intermediate metabolite in the glycolysis metabolic pathway and is utilized as a substrate for phospholipids synthesis. The initial and rate-limiting step of phospholipids synthesis is the synthesis of lysophosphatidic acid (LPA) from G3P and acyl-CoA mediated by glycerol 3-phosphate acyltransferases (GPATs). Since CD34+ acute leukemia cells contained significantly lower level of G3P, we hypothesized that leukemia cells actively consumed G3P and synthesized LPA by GPATs. GPATs are classified into four isoforms based on intracellular localization and substrate preference. GPAT1 and GPAT2 are mitochondrial GPATs that are localized to the mitochondrial outer membrane, but on the other hand, GPAT3 and GPAT4 are microsomal GPATs that are localized to the endoplasmic reticulum membrane, each encoded by independent genes. GPAT1 is identified as an essential gene for the growth of leukemia cells by RNAi screen analysis in the public database (DepMap). We found that CD34+ immature AML cells exhibited higher GPAT1 expression as compared to CD34- more differentiated AML cells and normal T cells. GPAT1 knockdown inhibited the proliferation of several acute leukemia cell lines including THP-1 and Kasumi-1 in vitro and in vivo. Moreover, a mitochondrial GPATs specific inhibitor (FSG67), which was originally developed as a drug to treat obesity and diabetes, suppressed the growth of the leukemia cell lines through the induction of G1 cell cycle arrest. Growth inhibition was rescued by exogenous administration of LPA, suggesting that the synthetic activity mediated by mitochondrial GPATs should be required for acute leukemia growth. Furthermore, FSG67 induced the apoptosis of leukemia cells derived from AML and ALL patients without affecting normal CD34+ HSPCs at least in vitro. We also confirmed that the injection of FSG67 resulted in the suppression of AML and ALL propagation in vivo using patient-derived xenograft models (see figure). GPAT1 regulates the mitochondrial function by producing LPA which is an essential metabolite for maintaining mitochondrial fusion. Actually, the amount of LPA was decreased in GPAT1 knockdown acute leukemia cells. We next examined mitochondrial energy production by extracellular flux assay, and found that GPAT1 knockdown as well as FSG67 significantly suppressed oxygen consumption rate of acute leukemia cells. Consistent with the impaired mitochondrial function, FSG67 suppressed the mitochondrial membrane potential, indicating that GPAT1 should play a pivotal role in maintaining leukemia-specific mitochondrial function. These results collectively suggest that the synthesis of LPA from G3P catalyzed by GPAT1 has a critical role in propagation of acute leukemia cells irrespective of their lineage origin. Thus, GPAT1 is a novel and common therapeutic target for human acute leukemia through suppressing leukemia-specific mitochondrial function. Figure Disclosures Akashi: Celgene, Kyowa Kirin, Astellas, Shionogi, Asahi Kasei, Chugai, Bristol-Myers Squibb: Research Funding; Sumitomo Dainippon, Kyowa Kirin: Consultancy.

scholarly journals Ampelopsin Inhibits Cell Proliferation and Induces Apoptosis in HL60 and K562 Leukemia Cells by Downregulating AKT and NF-κB Signaling Pathways

2021 ◽  
Vol 22 (8) ◽  
pp. 4265
Author(s):  
Jang Mi Han ◽  
Hong Lae Kim ◽  
Hye Jin Jung
Keyword(s):  
Signaling Pathways ◽  
Cell Lines ◽  
White Blood Cells ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Ros Generation ◽  
Anticancer Activities ◽  
Nuclear Condensation ◽  
Leukemia Cell Lines ◽  
Antileukemic Effect

Leukemia is a type of blood cancer caused by the rapid proliferation of abnormal white blood cells. Currently, several treatment options, including chemotherapy, radiation therapy, and bone marrow transplantation, are used to treat leukemia, but the morbidity and mortality rates of patients with leukemia are still high. Therefore, there is still a need to develop more selective and less toxic drugs for the effective treatment of leukemia. Ampelopsin, also known as dihydromyricetin, is a plant-derived flavonoid that possesses multiple pharmacological functions, including antibacterial, anti-inflammatory, antioxidative, antiangiogenic, and anticancer activities. However, the anticancer effect and mechanism of action of ampelopsin in leukemia remain unclear. In this study, we evaluated the antileukemic effect of ampelopsin against acute promyelocytic HL60 and chronic myelogenous K562 leukemia cells. Ampelopsin significantly inhibited the proliferation of both leukemia cell lines at concentrations that did not affect normal cell viability. Ampelopsin induced cell cycle arrest at the sub-G1 phase in HL60 cells but the S phase in K562 cells. In addition, ampelopsin regulated the expression of cyclins, cyclin-dependent kinases (CDKs), and CDK inhibitors differently in each leukemia cell. Ampelopsin also induced apoptosis in both leukemia cell lines through nuclear condensation, loss of mitochondrial membrane potential, increase in reactive oxygen species (ROS) generation, activation of caspase-9, caspase-3, and poly ADP-ribose polymerase (PARP), and regulation of Bcl-2 family members. Furthermore, the antileukemic effect of ampelopsin was associated with the downregulation of AKT and NF-κB signaling pathways. Moreover, ampelopsin suppressed the expression levels of leukemia stemness markers, such as Oct4, Sox2, CD44, and CD133. Taken together, our findings suggest that ampelopsin may be an attractive chemotherapeutic agent against leukemia.

Aurora-A kinase: a novel target of cellular immunotherapy for leukemia

Blood ◽  
2009 ◽  
Vol 113 (1) ◽  
pp. 66-74 ◽  
Author(s):  
Toshiki Ochi ◽  
Hiroshi Fujiwara ◽  
Koichiro Suemori ◽  
Taichi Azuma ◽  
Yoshihiro Yakushijin ◽  
...  
Keyword(s):  
Cell Lines ◽  
Leukemia Cell ◽  
Myelogenous Leukemia ◽  
Leukemia Cells ◽  
Cellular Immunotherapy ◽  
Aurora A Kinase ◽  
Aurora A ◽  
Hematopoietic Stem ◽  
Specific Ctls ◽  
Leukemia Cell Lines

Abstract Aurora-A kinase (Aur-A) is a member of the serine/threonine kinase family that regulates the cell division process, and has recently been implicated in tumorigenesis. In this study, we identified an antigenic 9–amino-acid epitope (Aur-A207-215: YLILEYAPL) derived from Aur-A capable of generating leukemia-reactive cytotoxic T lymphocytes (CTLs) in the context of HLA-A*0201. The synthetic peptide of this epitope appeared to be capable of binding to HLA-A*2402 as well as HLA-A*0201 molecules. Leukemia cell lines and freshly isolated leukemia cells, particularly chronic myelogenous leukemia (CML) cells, appeared to express Aur-A abundantly. Aur-A–specific CTLs were able to lyse human leukemia cell lines and freshly isolated leukemia cells, but not normal cells, in an HLA-A*0201–restricted manner. Importantly, Aur-A–specific CTLs were able to lyse CD34+ CML progenitor cells but did not show any cytotoxicity against normal CD34+ hematopoietic stem cells. The tetramer assay revealed that the Aur-A207-215 epitope–specific CTL precursors are present in peripheral blood of HLA-A*0201–positive and HLA-A*2402–positive patients with leukemia, but not in healthy individuals. Our results indicate that cellular immunotherapy targeting Aur-A is a promising strategy for treatment of leukemia.

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