title: Immunomorphological characterization and effects of 12-(S)-HETE on a dynamic intracellular pool of the alpha IIb beta 3-integrin in melanoma cells.
abstract: In metastatic B16a murine melanoma cells, alpha IIb beta 3 integrin was shown to be one of the key adhesion molecules responsible for matrix adhesion and spreading. Upon stimulation, alpha IIb beta 3 can be upregulated at the cell surface due to translocation of the receptor to the plasma membrane from an intracellular pool. Here we have characterized this integrin pool as a tubulovesicular structure (TVS) corresponding to endosomes. TVS was found to be associated temporarily with microtubules and intermediate filaments especially after protein kinase C (PKC) stimulation with a lipoxygenase metabolite of arachidonic acid, 12-(S)-hydroxyeicosatetraenoic acid [12-(S)-HETE]. After PKC stimulation, the predominantly vesicular TVS became elongated and alpha IIb beta 3 appeared at the apical plasma membrane and microvilli. Disruption of either the microtubules or intermediate filaments prevented the 12-(S)-HETE effect both on vesicular to tubular transition of TVS as well as on surface expression of this integrin. The connection with the Golgi system of the integrin-containing TVS was proved by a Golgi-inhibitor (brefeldin A) pretreatment, which prevented the PKC-stimulation-induced TVS elongation and subsequent receptor-upregulation at the cell surface. After a soluble ligand binding (mAb to the alpha IIb beta 3 complex) the surface receptor endocytosed back to the TVS indicating the presence of a dynamic, cytoskeleton associated integrin pool in melanoma cells.
authors.affiliation: 1st Institute of Pathology and Experimental Cancer Research, Semmelweis Medical University, Budapest, Hungary.
authors.forename: J
authors.initials: J
authors.lastname: Tímár
authors.forename: R
authors.initials: R
authors.lastname: Bazaz
authors.forename: V
authors.initials: V
authors.lastname: Kimler
authors.forename: M
authors.initials: M
authors.lastname: Haddad
authors.forename: D G
authors.initials: DG
authors.lastname: Tang
authors.forename: D
authors.initials: D
authors.lastname: Robertson
authors.forename: J
authors.initials: J
authors.lastname: Tovari
authors.forename: J D
authors.initials: JD
authors.lastname: Taylor
authors.forename: K V
authors.initials: KV
authors.lastname: Honn
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D000818:Animals; D003599:Cytoskeleton / Q000502:physiology; D011992:Endosomes / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology*; D016023:Integrins / Q000378:metabolism* / Q000648:ultrastructure; D008546:Melanoma, Experimental; D051379:Mice; D008854:Microscopy, Electron; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D014407:Tumor Cells, Cultured
chemical_list: D006893:Hydroxyeicosatetraenoic Acids; D016023:Integrins; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid