LIVIVO - The Search Portal for Life Sciences

zur deutschen Oberfläche wechseln
Advanced search

Search results

Result 1 - 10 of total 10

Search options

  1. Article: The wolf in sheep's clothing: Platelet-derived "pseudo self" impairs cancer cell "missing self" recognition by NK cells.

    Placke, Theresa / Kopp, Hans-Georg / Salih, Helmut Rainer

    Oncoimmunology

    2012  Volume 1, Issue 4, Page(s) 557–559

    Abstract: Metastasis is strongly inhibited in thrombocytopenic mice. This phenotype is reversed by NK cell depletion which indicates that platelets may facilitate tumor progression and metastasis by interfering with NK cell immunosurveillance. Understanding the ... ...

    Abstract Metastasis is strongly inhibited in thrombocytopenic mice. This phenotype is reversed by NK cell depletion which indicates that platelets may facilitate tumor progression and metastasis by interfering with NK cell immunosurveillance. Understanding the underlying mechanisms may help us to reinforce anti-tumor immunity and NK-based immunotherapy in cancer patients.
    Language English
    Publishing date 2012-05-23
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2645309-5
    ISSN 2162-402X ; 2162-4011
    ISSN (online) 2162-402X
    ISSN 2162-4011
    DOI 10.4161/onci.19367
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  2. Article ; Online: GITR ligand provided by thrombopoietic cells inhibits NK cell antitumor activity.

    Placke, Theresa / Salih, Helmut R / Kopp, Hans-Georg

    Journal of immunology (Baltimore, Md. : 1950)

    2012  Volume 189, Issue 1, Page(s) 154–160

    Abstract: Thrombocytopenia inhibits tumor growth and especially metastasis in mice, whereas additional depletion of NK cells reverts this antimetastatic phenotype. It has therefore been speculated that platelets may protect hematogenously disseminating tumor cells ...

    Abstract Thrombocytopenia inhibits tumor growth and especially metastasis in mice, whereas additional depletion of NK cells reverts this antimetastatic phenotype. It has therefore been speculated that platelets may protect hematogenously disseminating tumor cells from NK-dependent antitumor immunity. Tumor cells do not travel through the blood alone, but are rapidly coated by platelets, and this phenomenon has been proposed to shield disseminating tumor cells from NK-mediated lysis. However, the underlying mechanisms remain largely unclear. In this study, we show that megakaryocytes acquire expression of the TNF family member glucocorticoid-induced TNF-related ligand (GITRL) during differentiation, resulting in GITRL expression by platelets. Upon platelet activation, GITRL is upregulated on the platelet surface in parallel with the α-granular activation marker P-selectin. GITRL is also rapidly mobilized to the platelet surface following interaction with tumor cells, which results in platelet coating. Whereas GITRL, in the fashion of several other TNF family members, is capable of transducing reverse signals, no influence on platelet activation and function was observed upon GITRL triggering. However, platelet coating of tumor cells inhibited NK cell cytotoxicity and IFN-γ production that could partially be restored by blocking GITR on NK cells, thus indicating that platelet-derived GITRL mediates NK-inhibitory forward signaling via GITR. These data identify conferment of GITRL pseudoexpression to tumor cells by platelets as a mechanism by which platelets may alter tumor cell immunogenicity. Our data thus provide further evidence for the involvement of platelets in facilitating evasion of tumor cells from NK cell immune surveillance.
    MeSH term(s) Blood Platelets/immunology ; Blood Platelets/metabolism ; Cell Line ; Cell Line, Tumor ; Cytotoxicity, Immunologic/genetics ; Cytotoxicity, Immunologic/immunology ; Humans ; Killer Cells, Natural/immunology ; Killer Cells, Natural/metabolism ; Killer Cells, Natural/pathology ; Megakaryocytes/immunology ; Megakaryocytes/metabolism ; Tumor Escape/genetics ; Tumor Escape/immunology ; Tumor Necrosis Factors/biosynthesis ; Tumor Necrosis Factors/genetics ; Tumor Necrosis Factors/physiology ; Up-Regulation/genetics ; Up-Regulation/immunology
    Chemical Substances TNFSF18 protein, human ; Tumor Necrosis Factors
    Language English
    Publishing date 2012-07-01
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 3056-9
    ISSN 1550-6606 ; 0022-1767 ; 1048-3233 ; 1047-7381
    ISSN (online) 1550-6606
    ISSN 0022-1767 ; 1048-3233 ; 1047-7381
    DOI 10.4049/jimmunol.1103194
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  3. Article ; Online: Modulation of natural killer cell anti-tumor reactivity by platelets.

    Placke, Theresa / Kopp, Hans-Georg / Salih, Helmut Rainer

    Journal of innate immunity

    2011  Volume 3, Issue 4, Page(s) 374–382

    Abstract: Natural killer (NK) cells may prevent tumor progression and metastasis. Apart from the direct interaction with their targets, NK cell activity is influenced by the reciprocal interplay with other hematopoietic cells. While the interaction of NK cells e.g. ...

    Abstract Natural killer (NK) cells may prevent tumor progression and metastasis. Apart from the direct interaction with their targets, NK cell activity is influenced by the reciprocal interplay with other hematopoietic cells. While the interaction of NK cells e.g. with dendritic cells or monocytes/macrophages is well characterized, knowledge regarding their crosstalk with platelets, another central component of the blood, is still fragmentary. However, studies in mice and men clearly document a strong dependence of tumor progression and metastasis on quantitatively and functionally normal platelets. In mice, metastasis is inhibited by thrombocytopenia, and this effect is reversed by additional NK cell depletion, indicating that platelets may 'indirectly' contribute to tumor dissemination by impairing NK cell anti-tumor reactivity. In humans, circumstantial evidence indicates that metastasizing malignant cells do not travel through the blood alone, but efficiently attract and get coated by platelets, thereby causing release of platelet granule content. Beyond this secretion of various growth factors and cytokines/chemokines, platelets may also influence NK cell function by immunoregulatory molecules expressed on the platelet surface. Here, we review the available data regarding tumor-platelet-NK cell interaction focusing on metastatic tumor spread and discuss the molecular mechanisms underlying this trilateral crosstalk.
    MeSH term(s) Animals ; Blood Platelets/immunology ; Blood Platelets/metabolism ; Humans ; Killer Cells, Natural/immunology ; Killer Cells, Natural/metabolism ; Killer Cells, Natural/pathology ; Mice ; Neoplasm Metastasis/immunology ; Neoplasm Metastasis/pathology ; Neoplasms/immunology ; Neoplasms/metabolism ; Neoplasms/pathology ; Species Specificity
    Language English
    Publishing date 2011
    Publishing country Switzerland
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 2454158-8
    ISSN 1662-8128 ; 1662-811X
    ISSN (online) 1662-8128
    ISSN 1662-811X
    DOI 10.1159/000323936
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  4. Article ; Online: Glucocorticoid-induced TNFR-related (GITR) protein and its ligand in antitumor immunity: functional role and therapeutic modulation.

    Placke, Theresa / Kopp, Hans-Georg / Salih, Helmut Rainer

    Clinical & developmental immunology

    2010  Volume 2010, Page(s) 239083

    Abstract: The ability of the tumor necrosis factor receptor (TNFR) family member GITR to modulate immune responses has been the subject of multiple studies. Initially thought to be critically involved in governing functions of regulatory T cells, GITR and its ... ...

    Abstract The ability of the tumor necrosis factor receptor (TNFR) family member GITR to modulate immune responses has been the subject of multiple studies. Initially thought to be critically involved in governing functions of regulatory T cells, GITR and its ligand GITRL have meanwhile been found to modulate the reactivity of various different cell types and to influence a broad variety of immunological conditions including the immune response against tumors. Not only GITR, but also GITRL is capable of transducing signals, and the consequences of GITR-GITRL interaction may vary among different effector cell types, differ upon signal transduction via the receptor, the ligand, or both, depend on the level of an ongoing immune response, and even differ among mice and men. In this paper, we address available data on GITR and its ligand in immune responses and discuss the role and potential therapeutic modulation of this molecule system in antitumor immunity.
    MeSH term(s) Animals ; Glucocorticoid-Induced TNFR-Related Protein ; Humans ; Immunity ; Killer Cells, Natural/immunology ; Macrophages/immunology ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Neoplasms/immunology ; Neoplasms/therapy ; Receptors, Nerve Growth Factor/metabolism ; Receptors, Tumor Necrosis Factor/metabolism ; Signal Transduction ; T-Lymphocytes/immunology ; Tumor Necrosis Factors/metabolism
    Chemical Substances Glucocorticoid-Induced TNFR-Related Protein ; Receptors, Nerve Growth Factor ; Receptors, Tumor Necrosis Factor ; TNFRSF18 protein, human ; TNFSF18 protein, human ; Tumor Necrosis Factors
    Language English
    Publishing date 2010-09-26
    Publishing country Egypt
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 2119646-1
    ISSN 1740-2530 ; 1740-2522
    ISSN (online) 1740-2530
    ISSN 1740-2522
    DOI 10.1155/2010/239083
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  5. Article ; Online: Platelet-derived transforming growth factor-beta down-regulates NKG2D thereby inhibiting natural killer cell antitumor reactivity.

    Kopp, Hans-Georg / Placke, Theresa / Salih, Helmut Rainer

    Cancer research

    2009  Volume 69, Issue 19, Page(s) 7775–7783

    Abstract: Natural killer (NK) cells play an important role in cancer immunosurveillance and may prevent tumor progression and metastasis due to their ability to mediate direct cellular cytotoxicity and by releasing immunoregulatory cytokines, which shape adaptive ... ...

    Abstract Natural killer (NK) cells play an important role in cancer immunosurveillance and may prevent tumor progression and metastasis due to their ability to mediate direct cellular cytotoxicity and by releasing immunoregulatory cytokines, which shape adaptive immune responses. Their reactivity is governed by various activating and inhibitory molecules expressed on target cells and reciprocal interactions with other hematopoietic cells such as dendritic cells. In mice, thrombocytopenia inhibits metastasis, and this is reversed by NK cell depletion, suggesting that platelets are an important additional player in NK cell-tumor interaction. Moreover, it has been shown that metastasizing tumor cells do not travel through the blood alone but are rapidly coated by platelets. However, the knowledge about the molecular mechanisms by which platelets influence NK cells is fragmentary at best. Here we show that platelet-derived soluble factors, secreted on coating of tumor cells or after stimulation with classic platelet agonists, impair NK cell antitumor reactivity resulting in diminished granule mobilization, cytotoxicity, and IFN-gamma production. The impaired NK cell reactivity was not due to induction of apoptosis but mediated by down-regulation of the activating immunoreceptor natural killer group 2, member D (NKG2D) on NK cells by platelet-derived transforming growth factor beta (TGF-beta). Neutralization of TGF-beta in platelet releasate not only prevented NKG2D down-regulation but also restored NK cell antitumor reactivity. Thus, our data elucidate the molecular basis of the previously described influence of platelets on NK cell antitumor reactivity and suggest that therapeutic intervention in tumor cell-platelet interaction and the resulting TGF-beta release by platelets may serve to enhance antitumor immunity.
    MeSH term(s) Blood Platelets/immunology ; Cell Line, Tumor ; Down-Regulation ; HCT116 Cells ; Humans ; Interferon-gamma/biosynthesis ; Interferon-gamma/blood ; Killer Cells, Natural/immunology ; NK Cell Lectin-Like Receptor Subfamily K/biosynthesis ; NK Cell Lectin-Like Receptor Subfamily K/genetics ; Neoplasms/blood ; Neoplasms/immunology ; Platelet Activation ; Transforming Growth Factor beta/blood ; Transforming Growth Factor beta/immunology
    Chemical Substances KLRK1 protein, human ; NK Cell Lectin-Like Receptor Subfamily K ; Transforming Growth Factor beta ; Interferon-gamma (82115-62-6)
    Language English
    Publishing date 2009-10-01
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1432-1
    ISSN 1538-7445 ; 0008-5472
    ISSN (online) 1538-7445
    ISSN 0008-5472
    DOI 10.1158/0008-5472.CAN-09-2123
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  6. Article ; Online: Glucocorticoid-Induced TNFR-Related (GITR) Protein and Its Ligand in Antitumor Immunity

    Theresa Placke / Hans-Georg Kopp / Helmut Rainer Salih

    Clinical and Developmental Immunology, Vol

    Functional Role and Therapeutic Modulation

    2010  Volume 2010

    Abstract: The ability of the tumor necrosis factor receptor (TNFR) family member GITR to modulate immune responses has been the subject of multiple studies. Initially thought to be critically involved in governing functions of regulatory T cells, GITR and its ... ...

    Abstract The ability of the tumor necrosis factor receptor (TNFR) family member GITR to modulate immune responses has been the subject of multiple studies. Initially thought to be critically involved in governing functions of regulatory T cells, GITR and its ligand GITRL have meanwhile been found to modulate the reactivity of various different cell types and to influence a broad variety of immunological conditions including the immune response against tumors. Not only GITR, but also GITRL is capable of transducing signals, and the consequences of GITR-GITRL interaction may vary among different effector cell types, differ upon signal transduction via the receptor, the ligand, or both, depend on the level of an ongoing immune response, and even differ among mice and men. In this paper, we address available data on GITR and its ligand in immune responses and discuss the role and potential therapeutic modulation of this molecule system in antitumor immunity.
    Keywords Medicine ; R ; Internal medicine ; RC31-1245 ; Specialties of internal medicine ; RC581-951 ; Immunologic diseases. Allergy ; RC581-607
    Subject code 570
    Language English
    Publishing date 2010-01-01T00:00:00Z
    Publisher Hindawi Publishing Corporation
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    More links

    Kategorien

  7. Article: Modulation of Natural Killer Cell Anti-Tumor Reactivity by Platelets

    Placke, Theresa / Kopp, Hans-Georg / Salih, Helmut Rainer

    Journal of Innate Immunity

    2011  Volume 3, Issue 4, Page(s) 374–382

    Abstract: Natural killer (NK) cells may prevent tumor progression and metastasis. Apart from the direct interaction with their targets, NK cell activity is influenced by the reciprocal interplay with other hematopoietic cells. While the interaction of NK cells e.g. ...

    Institution Department of Hematology/Oncology, Eberhard Karls University, Tübingen, Germany
    Abstract Natural killer (NK) cells may prevent tumor progression and metastasis. Apart from the direct interaction with their targets, NK cell activity is influenced by the reciprocal interplay with other hematopoietic cells. While the interaction of NK cells e.g. with dendritic cells or monocytes/macrophages is well characterized, knowledge regarding their crosstalk with platelets, another central component of the blood, is still fragmentary. However, studies in mice and men clearly document a strong dependence of tumor progression and metastasis on quantitatively and functionally normal platelets. In mice, metastasis is inhibited by thrombocytopenia, and this effect is reversed by additional NK cell depletion, indicating that platelets may ‘indirectly’ contribute to tumor dissemination by impairing NK cell anti-tumor reactivity. In humans, circumstantial evidence indicates that metastasizing malignant cells do not travel through the blood alone, but efficiently attract and get coated by platelets, thereby causing release of platelet granule content. Beyond this secretion of various growth factors and cytokines/chemokines, platelets may also influence NK cell function by immunoregulatory molecules expressed on the platelet surface. Here, we review the available data regarding tumor-platelet-NK cell interaction focusing on metastatic tumor spread and discuss the molecular mechanisms underlying this trilateral crosstalk.
    Keywords Natural killer cells ; Platelets ; Cancer ; Metastasis
    Language English
    Publishing date 2011-03-12
    Publisher S. Karger AG
    Publishing place Basel, Switzerland
    Document type Article
    Note Review
    ZDB-ID 2454158-8
    ISSN 1662-8128 ; 1662-811X
    ISSN (online) 1662-8128
    ISSN 1662-811X
    DOI 10.1159/000323936
    Database Karger publisher's database

    More links

    Kategorien

  8. Article ; Online: Platelet-derived MHC class I confers a pseudonormal phenotype to cancer cells that subverts the antitumor reactivity of natural killer immune cells.

    Placke, Theresa / Örgel, Melanie / Schaller, Martin / Jung, Gundram / Rammensee, Hans-Georg / Kopp, Hans-Georg / Salih, Helmut Rainer

    Cancer research

    2012  Volume 72, Issue 2, Page(s) 440–448

    Abstract: Natural killer (NK) cells are cytotoxic lymphocytes that play an important role in tumor immunosurveillance, preferentially eliminating targets with low or absent expression of MHC class I and stress-induced expression of ligands for activating NK ... ...

    Abstract Natural killer (NK) cells are cytotoxic lymphocytes that play an important role in tumor immunosurveillance, preferentially eliminating targets with low or absent expression of MHC class I and stress-induced expression of ligands for activating NK receptors. Platelets promote metastasis by protecting disseminating tumor cells from NK cell immunosurveillance, but the underlying mechanisms are not well understood. In this study, we show that tumor cells rapidly get coated in the presence of platelets in vitro, and circulating tumor cells of cancer patients display coexpression of platelet markers. Flow cytometry, immunofluorescent staining, confocal microscopy, and analyses on an ultrastructural level using immunoelectron microscopy revealed that such coating may cause transfer of MHC class I onto the tumor cell surface resulting in high-level expression of platelet-derived normal MHC class I. The resulting "phenotype of false pretenses" disrupts recognition of tumor cell missing self, thereby impairing cytotoxicity and IFN-γ production by NK cells. Thus, our data indicate that platelets, by conferring an unsuspicious "pseudonormal" phenotype, may enable a molecular mimicry that allows metastasizing tumor cells to downregulate MHC class I, to escape T-cell-mediated immunity without inducing susceptibility to NK cell reactivity.
    MeSH term(s) Cell Line, Tumor ; Female ; Histocompatibility Antigens Class I/blood ; Histocompatibility Antigens Class I/immunology ; Humans ; Killer Cells, Natural/immunology ; Neoplasms/genetics ; Neoplasms/immunology ; Neoplasms/pathology ; Phenotype ; Receptors, Immunologic/immunology
    Chemical Substances Histocompatibility Antigens Class I ; Receptors, Immunologic
    Language English
    Publishing date 2012-01-15
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1432-1
    ISSN 1538-7445 ; 0008-5472
    ISSN (online) 1538-7445
    ISSN 0008-5472
    DOI 10.1158/0008-5472.CAN-11-1872
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  9. Article ; Online: The BCR/ABL-inhibitors imatinib, nilotinib and dasatinib differentially affect NK cell reactivity.

    Salih, Julia / Hilpert, Julia / Placke, Theresa / Grünebach, Frank / Steinle, Alexander / Salih, Helmut Rainer / Krusch, Matthias

    International journal of cancer

    2010  Volume 127, Issue 9, Page(s) 2119–2128

    Abstract: In chronic myeloid leukemia (CML), BCR/ABL-mediated oncogenic signaling can be targeted with the BCR/ABL-inhibitors Imatinib, Nilotinib and Dasatinib. However, these agents may also affect anti-tumor immunity. Here, we analyzed the effects of the 3 BCR/ ... ...

    Abstract In chronic myeloid leukemia (CML), BCR/ABL-mediated oncogenic signaling can be targeted with the BCR/ABL-inhibitors Imatinib, Nilotinib and Dasatinib. However, these agents may also affect anti-tumor immunity. Here, we analyzed the effects of the 3 BCR/ABL-inhibitors on natural killer (NK) cell reactivity. Exposure of CML cells (K562, Meg-01) to pharmacological concentrations of Imatinib, Nilotinib and Dasatinib diminished expression of ligands for the activating immunoreceptor NKG2D to a similar extent. This resulted in comparably reduced NK cell cytotoxicity and IFN-gamma production. When direct effects on NK cell responses to K562 and primary CML cells as well as activating cytokines were studied, Dasatinib was found to abrogate NK cytotoxicity and cytokine production. Nilotinib did not alter cytotoxicity but, at high levels, impaired NK cytokine production, while Imatinib had no direct influence on NK cell reactivity. Of note, Nilotinib, but not the other BCR/ABL-inhibitors increased cell death within the preferentially cytokine-secreting CD56(bright)CD16(-) NK cell subset, which may, at least in part, serve to explain the effect of Nilotinib on NK cytokine production. Analysis of NK cell signaling revealed that Dasatinib inhibited proximal signaling events leading to decreased phosphorylation of PI3K and ERK that are crucial for NK cell reactivity. Imatinib and Nilotinib, in contrast, showed no relevant effect on NK cell PI3K or ERK activity. In light of the potential role of NK cells in the immunesurveillance of residual leukemia and for future combinatory immunotherapeutic approaches, our data indicate that choice and dosing of the most suitable BCR/ABL-inhibitor for a given patient require careful consideration.
    MeSH term(s) Aluminum Silicates/metabolism ; Antineoplastic Agents/pharmacology ; Benzamides ; Cell Line, Tumor ; Cytotoxicity, Immunologic/drug effects ; Dasatinib ; Down-Regulation ; Fusion Proteins, bcr-abl/antagonists & inhibitors ; Histocompatibility Antigens Class I/metabolism ; Humans ; Imatinib Mesylate ; Interferon-gamma/metabolism ; K562 Cells ; Killer Cells, Natural/drug effects ; Killer Cells, Natural/immunology ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/embryology ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/immunology ; Piperazines/pharmacology ; Pyrimidines/pharmacology ; Thiazoles/pharmacology
    Chemical Substances Aluminum Silicates ; Antineoplastic Agents ; Benzamides ; Histocompatibility Antigens Class I ; MICB antigen ; Piperazines ; Pyrimidines ; Thiazoles ; Interferon-gamma (82115-62-6) ; Imatinib Mesylate (8A1O1M485B) ; Fusion Proteins, bcr-abl (EC 2.7.10.2) ; nilotinib (F41401512X) ; Dasatinib (RBZ1571X5H) ; mica (V8A1AW0880)
    Language English
    Publishing date 2010-01-29
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 218257-9
    ISSN 1097-0215 ; 0020-7136
    ISSN (online) 1097-0215
    ISSN 0020-7136
    DOI 10.1002/ijc.25233
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  10. Article ; Online: Requirement for CDK6 in MLL-rearranged acute myeloid leukemia.

    Placke, Theresa / Faber, Katrin / Nonami, Atsushi / Putwain, Sarah L / Salih, Helmut R / Heidel, Florian H / Krämer, Alwin / Root, David E / Barbie, David A / Krivtsov, Andrei V / Armstrong, Scott A / Hahn, William C / Huntly, Brian J / Sykes, Stephen M / Milsom, Michael D / Scholl, Claudia / Fröhling, Stefan

    Blood

    2014  Volume 124, Issue 1, Page(s) 13–23

    Abstract: Chromosomal rearrangements involving the H3K4 methyltransferase mixed-lineage leukemia (MLL) trigger aberrant gene expression in hematopoietic progenitors and give rise to an aggressive subtype of acute myeloid leukemia (AML). Insights into MLL fusion- ... ...

    Abstract Chromosomal rearrangements involving the H3K4 methyltransferase mixed-lineage leukemia (MLL) trigger aberrant gene expression in hematopoietic progenitors and give rise to an aggressive subtype of acute myeloid leukemia (AML). Insights into MLL fusion-mediated leukemogenesis have not yet translated into better therapies because MLL is difficult to target directly, and the identity of the genes downstream of MLL whose altered transcription mediates leukemic transformation are poorly annotated. We used a functional genetic approach to uncover that AML cells driven by MLL-AF9 are exceptionally reliant on the cell-cycle regulator CDK6, but not its functional homolog CDK4, and that the preferential growth inhibition induced by CDK6 depletion is mediated through enhanced myeloid differentiation. CDK6 essentiality is also evident in AML cells harboring alternate MLL fusions and a mouse model of MLL-AF9-driven leukemia and can be ascribed to transcriptional activation of CDK6 by mutant MLL. Importantly, the context-dependent effects of lowering CDK6 expression are closely phenocopied by a small-molecule CDK6 inhibitor currently in clinical development. These data identify CDK6 as critical effector of MLL fusions in leukemogenesis that might be targeted to overcome the differentiation block associated with MLL-rearranged AML, and underscore that cell-cycle regulators may have distinct, noncanonical, and nonredundant functions in different contexts.
    MeSH term(s) Animals ; Cell Line, Tumor ; Cyclin-Dependent Kinase 6/metabolism ; Flow Cytometry ; Gene Expression Profiling ; Humans ; Immunoblotting ; Leukemia, Myeloid, Acute/genetics ; Leukemia, Myeloid, Acute/metabolism ; Mice ; Mice, Inbred C57BL ; Myeloid-Lymphoid Leukemia Protein/genetics ; Oncogene Proteins, Fusion/genetics ; Oncogene Proteins, Fusion/metabolism ; RNA, Small Interfering ; Reverse Transcriptase Polymerase Chain Reaction ; Transduction, Genetic
    Chemical Substances Oncogene Proteins, Fusion ; RNA, Small Interfering ; Myeloid-Lymphoid Leukemia Protein (149025-06-9) ; Cyclin-Dependent Kinase 6 (EC 2.7.11.22)
    Language English
    Publishing date 2014-04-24
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 80069-7
    ISSN 1528-0020 ; 0006-4971
    ISSN (online) 1528-0020
    ISSN 0006-4971
    DOI 10.1182/blood-2014-02-558114
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

To top