title: The chemokine receptor CXCR4 enhances integrin-mediated in vitro adhesion and facilitates engraftment of leukemic precursor-B cells in the bone marrow.
abstract: OBJECTIVE
  It has been demonstrated that acute lymphoblastic leukemia (ALL) blasts migrate into layers of bone marrow fibroblasts (BMF) in vitro using the beta1 integrins VLA-4 and VLA-5, and that the chemokine SDF-1 and its receptor CXCR4 influences ALL migration. We investigated whether this effect was due to SDF-1-mediated induction of adhesion through beta1 integrins.
  
  
  METHODS
  Adhesion of pre-B ALL cells or the cell line NALM6 to extracellular matrix proteins was examined using short-term in vitro binding assays. The effects of exposure of cells to SDF-1, antibodies to CXCR4, and the G protein inhibitor pertussis toxin (PTX) were assessed. The consequences of down regulation of CXCR4 on the in vivo behavior of pre-B ALL cells after injection into sublethally irradiated NOD/SCID mice was studied.
  
  
  RESULTS
  Treatment with SDF-1 of NALM6 cells or cells from cases of precursor-B ALL resulted in a doubling of adhesion to fibronectin, laminin, and VCAM-1, but had no effect on binding to collagens I or IV. Antibodies to CXCR4 and PTX inhibited SDF-1-induced adhesion on these substrates. NALM6 cells with CXCR4 expression downregulated by SDF-1 exposure demonstrated a reduced capacity to engraft into the bone marrow of NOD/SCID mice, with only 22 +/- 11% of marrow cells being of human origin in mice receiving SDF-1-treated cells compared to 48 +/- 5% in mice receiving untreated cells (p < 0.001). The homing of SDF-1-treated cells to the bone marrow after 24 hours was also reduced by 72 +/- 16% compared to control cells.
  
  
  CONCLUSIONS
  These data show that SDF-1 and CXCR4 are involved in regulation of beta1 integrin function, and are important for the localization of pre-B cells to the bone marrow in vivo.
authors.affiliation: Westmead Institute for Cancer Research, Westmead Millennium Institute, Westmead, Australia.
authors.forename: W
authors.initials: W
authors.lastname: Shen
authors.forename: L J
authors.initials: LJ
authors.lastname: Bendall
authors.forename: D J
authors.initials: DJ
authors.lastname: Gottlieb
authors.forename: K F
authors.initials: KF
authors.lastname: Bradstock
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001402:B-Lymphocytes / Q000473:pathology*; D001854:Bone Marrow Cells / Q000473:pathology*; D002051:Burkitt Lymphoma / Q000473:pathology; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000494:pharmacology* / Q000502:physiology; D015536:Down-Regulation / Q000187:drug effects*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D051379:Mice; D016513:Mice, SCID; D037342:Pertussis Toxin; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000473:pathology; D011485:Protein Binding; D019718:Receptors, CXCR4 / Q000187:drug effects / Q000502:physiology*; D014183:Transplantation, Heterologous / Q000276:immunology; D014407:Tumor Cells, Cultured; D019010:Vascular Cell Adhesion Molecule-1 / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D000906:Antibodies; C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; C515256:Cxcl12 protein, mouse; D016326:Extracellular Matrix Proteins; D019718:Receptors, CXCR4; D019010:Vascular Cell Adhesion Molecule-1; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin