title: CD9, a key actor in the dissemination of lymphoblastic leukemia, modulating CXCR4-mediated migration via RAC1 signaling.
abstract: CD9, a member of the tetraspanin family, has been implicated in hematopoietic and leukemic stem cell homing. We investigated the role of CD9 in the dissemination of B acute lymphoblastic leukemia (B-ALL) cells, by stably downregulating CD9 in REH and NALM6 cells. CD9 expression was associated with higher levels of REH cell adhesion to fibronectin and C-X-C motif chemokine receptor 4 (CXCR4)-mediated migration. Death occurred later in NOD/SCID mice receiving REH cells depleted of CD9 for transplantation than in mice receiving control cells. After C-X-C motif chemokine ligand 12 (CXCL12) stimulation, CD9 promoted the formation of long cytoplasmic actin-rich protrusions. We demonstrated that CD9 enhanced RAC1 activation, in both REH cells and blasts from patients. Conversely, the overexpression of a competing CD9 C-terminal tail peptide in REH cytoplasm decreased RAC1 activation and cytoplasmic extension formation in response to CXCL12. Finally, the inhibition of RAC1 activation decreased migration in vitro, and the depletion of RAC1 protein from transplanted REH cells increased mouse survival. Furthermore, a testis-conditioned medium induced the migration of REH and NALM6 cells, and this migration was impeded by an anti-CD9 antibody. The level of CD9 expression also influenced the homing of these cells in mouse testes. These findings demonstrate, for the first time, that CD9 plays a key role in the CXCR4-mediated migration and engraftment of B-ALL cells in the bone marrow or testis, through RAC1 activation.
authors: Centre National de la Recherche Scientifique (CNRS) Unités Mixtes de Recherche (UMR) 6290, Institut de Génétique et Développement de Rennes and Structure Fédérative de Recherche (SFR) en Biologie et Santé de Rennes Biosit, Unité Mixte de Service (UMS) CNRS 3480/US INSERM 018, Université de Rennes 1, Rennes, France;
authors: Marie-Pierre
authors: MP
authors: Arnaud
authors: Centre National de la Recherche Scientifique (CNRS) Unités Mixtes de Recherche (UMR) 6290, Institut de Génétique et Développement de Rennes and Structure Fédérative de Recherche (SFR) en Biologie et Santé de Rennes Biosit, Unité Mixte de Service (UMS) CNRS 3480/US INSERM 018, Université de Rennes 1, Rennes, France;
authors: Audrey
authors: A
authors: Vallée
authors: Centre National de la Recherche Scientifique (CNRS) Unités Mixtes de Recherche (UMR) 6290, Institut de Génétique et Développement de Rennes and Structure Fédérative de Recherche (SFR) en Biologie et Santé de Rennes Biosit, Unité Mixte de Service (UMS) CNRS 3480/US INSERM 018, Université de Rennes 1, Rennes, France; Department of OncoPediatrics, Rennes University Hospital, Rennes, France;
authors: Guillaume
authors: G
authors: Robert
authors: Centre National de la Recherche Scientifique (CNRS) Unités Mixtes de Recherche (UMR) 6290, Institut de Génétique et Développement de Rennes and Structure Fédérative de Recherche (SFR) en Biologie et Santé de Rennes Biosit, Unité Mixte de Service (UMS) CNRS 3480/US INSERM 018, Université de Rennes 1, Rennes, France; Department of OncoPediatrics, Rennes University Hospital, Rennes, France;
authors: Jacinthe
authors: J
authors: Bonneau
authors: INSERM UMR U978, Adaptateurs de Signalisation en Hématologie, Université Paris 13, Unité de Formation et de Recherche (UFR) de Santé, Médecine et Biologie Humaine (SMBH), Bobigny, France; and.
authors: Christine
authors: C
authors: Leroy
authors: INSERM UMR U978, Adaptateurs de Signalisation en Hématologie, Université Paris 13, Unité de Formation et de Recherche (UFR) de Santé, Médecine et Biologie Humaine (SMBH), Bobigny, France; and.
authors: Nadine
authors: N
authors: Varin-Blank
authors: Centre National de la Recherche Scientifique (CNRS) Unités Mixtes de Recherche (UMR) 6290, Institut de Génétique et Développement de Rennes and Structure Fédérative de Recherche (SFR) en Biologie et Santé de Rennes Biosit, Unité Mixte de Service (UMS) CNRS 3480/US INSERM 018, Université de Rennes 1, Rennes, France;
authors: Anne-Gaëlle
authors: AG
authors: Rio
authors: Centre National de la Recherche Scientifique (CNRS) Unités Mixtes de Recherche (UMR) 6290, Institut de Génétique et Développement de Rennes and Structure Fédérative de Recherche (SFR) en Biologie et Santé de Rennes Biosit, Unité Mixte de Service (UMS) CNRS 3480/US INSERM 018, Université de Rennes 1, Rennes, France;
authors: Marie-Bérengère
authors: MB
authors: Troadec
authors: Centre National de la Recherche Scientifique (CNRS) Unités Mixtes de Recherche (UMR) 6290, Institut de Génétique et Développement de Rennes and Structure Fédérative de Recherche (SFR) en Biologie et Santé de Rennes Biosit, Unité Mixte de Service (UMS) CNRS 3480/US INSERM 018, Université de Rennes 1, Rennes, France; Department of Medical Genomic, Rennes University Hospital, Rennes, France.
authors: Marie-Dominique
authors: MD
authors: Galibert
authors: Centre National de la Recherche Scientifique (CNRS) Unités Mixtes de Recherche (UMR) 6290, Institut de Génétique et Développement de Rennes and Structure Fédérative de Recherche (SFR) en Biologie et Santé de Rennes Biosit, Unité Mixte de Service (UMS) CNRS 3480/US INSERM 018, Université de Rennes 1, Rennes, France; Department of OncoPediatrics, Rennes University Hospital, Rennes, France;
authors: Virginie
authors: V
authors: Gandemer
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D001853:Bone Marrow / Q000378:metabolism / Q000473:pathology; D002448:Cell Adhesion; D002465:Cell Movement; D049109:Cell Proliferation; D054377:Chemokine CXCL12 / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009479:Neuropeptides / Q000378:metabolism*; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism* / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D019718:Receptors, CXCR4 / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013737:Testis / Q000378:metabolism / Q000473:pathology; D060245:Tetraspanin 29 / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
chemical_list: C514936:CXCR4 protein, mouse; C554870:Cd9 protein, mouse; D054377:Chemokine CXCL12; C515256:Cxcl12 protein, mouse; D009479:Neuropeptides; D012333:RNA, Messenger; C484602:Rac1 protein, mouse; D019718:Receptors, CXCR4; D060245:Tetraspanin 29; D020830:rac1 GTP-Binding Protein