Phosphatidylinositol 3-kinase/Akt activation by integrin-tumor matrix interaction suppresses Fas-mediated apoptosis in T cells

J Immunol. 2007 Oct 1;179(7):4589-97. doi: 10.4049/jimmunol.179.7.4589.

Abstract

It has recently become apparent that the microenvironment made up of the extracellular matrix may affect cell signaling. In this study, we evaluated Fas-triggered apoptosis in T cells in contact with tumor cells, which resembles the cell-to-cell interactions found in tumor regions. Jurkat cells were less susceptible to the Fas-mediated apoptosis when cocultured with U118, HeLa, A549, and Huh-7 tumor cells. This was indicated by less plasma membrane alteration, an amelioration of the loss of mitochondria membrane potential, a decrease in caspase-8 and caspase-3 activation, a decrease in DNA fragmentation factor-45/35 cleavage, and a reduction in the breakage of DNA when compared with Jurkat cells cultured alone. In contrast, the tumor cell lines MCF-7 and HepG2 produced no such protective effect. This protective event was independent of the expression of Fas ligand on the tumor cells. Interrupting the beta integrins-matrix interaction diminished the coculture effect. In Jurkat cells, cell matrix contact reduced the assembly of the Fas death-inducing signaling complex and Bcl-x(L) cleavage, but enhanced the phosphorylation of ERK1/2, p38 MAPK, and Akt. Only PI3K inhibitor, but not kinase inhibitors for MEK, ERK1/2, p38 MAPK, JNK, protein kinase C, and protein kinase A, completely abolished this tumor cell contact-associated protection and in parallel restored Fas-induced Bcl-x(L) cleavage as well as decreasing the phosphorylation of Bad at serine 136. Together, our results indicate that stimulation of the beta integrin signal of T cells by contact with tumor cells may trigger a novel protective signaling through the PI3K/Akt pathway of T cells against Fas-mediated apoptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies / immunology
  • Apoptosis
  • Cell Line
  • Coculture Techniques
  • Enzyme Activation
  • Humans
  • Integrins / metabolism*
  • Mice
  • Mitogen-Activated Protein Kinases / metabolism
  • Neoplasms / metabolism*
  • Neoplasms / pathology
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism*
  • T-Lymphocytes / cytology*
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism*
  • bcl-Associated Death Protein / metabolism
  • bcl-X Protein / metabolism
  • fas Receptor / immunology
  • fas Receptor / metabolism*

Substances

  • Antibodies
  • CH-11 anti-fas antibody, human
  • Integrins
  • bcl-Associated Death Protein
  • bcl-X Protein
  • fas Receptor
  • Phosphatidylinositol 3-Kinases
  • Proto-Oncogene Proteins c-akt
  • Mitogen-Activated Protein Kinases