title: Ligation of CD44 leads to killing activity in human peripheral mononuclear cells via MAP kinase and tyrosine kinases.
abstract: CD44 is a widely distributed transmembrane glycoprotein associated with various lymphocyte functions, including lympho-hemopoiesis, adhesion to the extracellular matrix, and T cell activation. In this study, we examined the mechanisms of CD44 involvement in regulating the killing activity of human peripheral mononuclear cells (PMC). An anti-CD44 monoclonal antibody (mAb) J173 enhanced the killing activity of PMC against Daudi and K562 cells in a dose-dependent manner. The increased cytotoxicity peaked at mAb concentration of 1.25 microg/ml. Under this condition, triggering of CD44 enhanced the killing activity by 1.5- and 2.2-fold at an effector-to-target (E/T) ratio of 20 for Daudi and K562 cells, respectively. Cytotoxic activity was remarkably diminished by treatment of PMC with concanamycin A, suggesting that this PMC-mediated cytotoxicity is mainly exerted via the perforin pathway. Moreover, we found that ligation of CD44 transduced signals to PMC that led to the tyrosine phosphorylation of several intracellular proteins and activation of mitogen-activated protein (MAP) kinase. Genistein, an inhibitor of tyrosine phosphorylation, and PD98059, an inhibitor of MAP kinase, suppressed CD44-induced enhancement of cytotoxicity. These results suggest that the CD44 molecule, which is a main receptor for hyaluronan known to be expressed on the surface of tumor cells, plays an important role in PMC-mediated cytotoxicity, and that tyrosine kinases and MAP kinase are essential for CD44-mediated signaling in cytotoxicity.
authors.affiliation: Department of Internal Medicine, Social Insurance Funabashi Central Hospital, Chiba, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ishizuka
authors.forename: Akira
authors.initials: A
authors.lastname: Yokota
authors.forename: Miki
authors.initials: M
authors.lastname: Nishimura
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Saito
authors.forename: Chiaki
authors.initials: C
authors.lastname: Nakaseko
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D045744:Cell Line, Tumor; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D005434:Flow Cytometry; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D018960:Hyaluronan Receptors / Q000097:blood / Q000276:immunology*; D006820:Hyaluronic Acid / Q000494:pharmacology; D020014:K562 Cells; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D018942:Macrolides / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000097:blood / Q000276:immunology*; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000097:blood / Q000276:immunology*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000911:Antibodies, Monoclonal; D004791:Enzyme Inhibitors; D005419:Flavonoids; D018960:Hyaluronan Receptors; D018942:Macrolides; C036978:concanamycin A; D006820:Hyaluronic Acid; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one