Regulation of gap junctions in melanoma and their impact on Melan-A/MART-1-specific CD8⁺ T lymphocyte emergence

J Mol Med (Berl). 2013 Oct;91(10):1207-20. doi: 10.1007/s00109-013-1058-5. Epub 2013 Jun 7.


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.

Key message: 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.

MeSH terms

  • Antineoplastic Agents, Alkylating / pharmacology
  • Apoptosis / genetics
  • Apoptosis / immunology
  • CD8-Positive T-Lymphocytes / immunology*
  • Cell Line, Tumor
  • Connexin 43 / genetics
  • Connexin 43 / metabolism
  • Cytotoxicity, Immunologic / genetics
  • Dacarbazine / pharmacology
  • Gap Junctions / drug effects
  • Gap Junctions / immunology*
  • Gap Junctions / metabolism
  • Gene Expression
  • Humans
  • Hypoxia
  • Immunological Synapses / metabolism
  • Interferon-gamma / pharmacology
  • MART-1 Antigen / immunology*
  • Melanoma / genetics
  • Melanoma / immunology*
  • Melanoma / metabolism
  • Oxidative Stress
  • Protein Transport
  • T-Lymphocytes, Cytotoxic / immunology
  • T-Lymphocytes, Cytotoxic / metabolism


  • Antineoplastic Agents, Alkylating
  • Connexin 43
  • MART-1 Antigen
  • Dacarbazine
  • Interferon-gamma