title: Regulation of gap junctions in melanoma and their impact on Melan-A/MART-1-specific CD8⁺ T lymphocyte emergence.
abstract: Gap junctions (GJs) enable intercellular communication between adjacent cells through channels of connexins. Using a three-dimensional construct, we previously showed that endothelial and tumor cells formed GJs, allowing melanoma-specific T lymphocytes to recognize and kill melanoma-derived endothelial cells. We demonstrate here on histological sections of melanoma biopsies that GJ formation occurs in vivo between tumor and endothelial cells and between T lymphocytes and target cells. We also show an in vitro increase of GJ formation in melanoma and endothelial cells following dacarbazin and interferon gamma (IFN-γ) treatment or hypoxic stress induction. Our data indicate that although connexin 43 (Cx43), the main GJ protein of the immune system, was localized at the immunological synapse between T lymphocyte and autologous melanoma cells, its over-expression or inhibition of GJs does not interfere with cytotoxic T lymphocyte (CTL) clone lytic function. In contrast, we showed that inhibition of GJs by oleamide during stimulation of resting PBMCs with Melan-A natural and analog peptides resulted in a decrease in antigen (Ag) specific CD8(+) T lymphocyte induction. These Ag-specific CD8(+) cells displayed paradoxically stronger reactivity as revealed by CD107a degranulation and IFN-γ secretion. These findings indicate that Cx43 does not affect lytic function of differentiated CTL, but reveal a major role for GJs in the regulation of antigen CD8(+)-naïve T lymphocyte activation.
  
  
  CONCLUSIONS
  GJ formation occurs in vivo between T lymphocytes and tumor cells Cx43 localized at the immunological synapse between T and autologous melanoma cells Inhibition of GJs resulted in a decrease in Ag-specific CD8(+) T lymphocyte induction A role for GJs in the regulation of antigen CD8(+)-naïve T lymphocyte activation.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM U753), Institut Fédératif de Recherche 54 (IFR54), Institut Gustave Roussy, 39 Rue Camille Desmoulins, 94805, Villejuif, France.
authors.forename: Houssem
authors.initials: H
authors.lastname: Benlalam
authors.forename: Thibault
authors.initials: T
authors.lastname: Carré
authors.forename: Abdelali
authors.initials: A
authors.lastname: Jalil
authors.forename: Zaeem
authors.initials: Z
authors.lastname: Noman
authors.forename: Bernard
authors.initials: B
authors.lastname: Caillou
authors.forename: Philippe
authors.initials: P
authors.lastname: Vielh
authors.forename: Andrés
authors.initials: A
authors.lastname: Tittarelli
authors.forename: Caroline
authors.initials: C
authors.lastname: Robert
authors.forename: Salem
authors.initials: S
authors.lastname: Chouaib
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D017209:Apoptosis / Q000235:genetics / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D045744:Cell Line, Tumor; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D003606:Dacarbazine / Q000494:pharmacology; D017629:Gap Junctions / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D000860:Hypoxia; D054992:Immunological Synapses / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology; D058965:MART-1 Antigen / Q000276:immunology*; D008545:Melanoma / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D018384:Oxidative Stress; D021381:Protein Transport; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism
chemical_list: D018906:Antineoplastic Agents, Alkylating; D018031:Connexin 43; D058965:MART-1 Antigen; D003606:Dacarbazine; D007371:Interferon-gamma