title: Constitutively polarized granules prime KHYG-1 NK cells.
abstract: The major mechanism for NK cell lysis of tumor cells is granule-mediated cytotoxicity. Polarization of granules is a prelude to the release of their cytotoxic contents in response to target-cell binding. We describe the novel observation of constitutive granule polarization in the cytotoxic NK cell line, KHYG-1. Continuous degranulation of KHYG-1 cells, however, does not occur and still requires target-cell contact. Disruption of microtubules with colcemid is sufficient to disperse the granules in KHYG-1 and significantly decreases cytotoxicity. A similar effect is not obtained by inhibiting extracellular signal-related kinase 2 (ERK2), the most distal kinase investigated in the cytolytic pathway. Disruption of microtubules significantly down-regulates activation receptors, NKp44 and NKG2D, implicating them as potential microtubule-trafficking receptors. Such changes in upstream receptor expression may have caused deactivation of ERK2, since NKG2D cross-linking also leads to receptor down-regulation and diminished ERK phosphorylation. Thus, a functional role for NKG2D in KHYG-1 cytotoxicity is demonstrated. Moreover, the novel primed state may contribute to the high cytotoxicity exhibited by KHYG-1.
authors.affiliation: Department of Medical Oncology and Hematology, Princess Margaret Hospital/Ontario Cancer Institute, 610 University Avenue, Suite 5-211, Toronto, ON M5G2M9, Canada. garnet.suck@uhn.on.ca
authors.forename: Garnet
authors.initials: G
authors.lastname: Suck
authors.forename: Donald R
authors.initials: DR
authors.lastname: Branch
authors.forename: Paola
authors.initials: P
authors.lastname: Aravena
authors.forename: Mark
authors.initials: M
authors.lastname: Mathieson
authors.forename: Simone
authors.initials: S
authors.lastname: Helke
authors.forename: Armand
authors.initials: A
authors.lastname: Keating
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D002460:Cell Line; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D003602:Cytotoxicity, Immunologic; D003703:Demecolcine / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism; D018613:Microscopy, Confocal; D008870:Microtubules / Q000187:drug effects; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000378:metabolism; D055655:NK Cell Lectin-Like Receptor Subfamily K; D055629:Natural Cytotoxicity Triggering Receptor 2; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D011971:Receptors, Immunologic / Q000187:drug effects / Q000378:metabolism; D055607:Receptors, Natural Killer Cell
chemical_list: D000972:Antineoplastic Agents, Phytogenic; C527085:KLRK1 protein, human; C112837:NCR2 protein, human; D055655:NK Cell Lectin-Like Receptor Subfamily K; D055629:Natural Cytotoxicity Triggering Receptor 2; D011971:Receptors, Immunologic; D055607:Receptors, Natural Killer Cell; D019950:Mitogen-Activated Protein Kinase 1; D003703:Demecolcine