Role of Fas and granule exocytosis pathways in tumor-infiltrating T lymphocyte-induced apoptosis of autologous human lung-carcinoma cells

Int J Cancer. 2001 Mar 15;91(6):772-7. doi: 10.1002/1097-0215(200002)9999:9999<::aid-ijc1132>;2-v.


We have isolated a cytotoxic T lymphocyte (CTL) clone, Heu161, that reacts specifically with the human autologous lung carcinoma cell line IGR-Heu. We first demonstrated that IGR-Heu lacked Fas-receptor expression and was resistant to CD95-induced apoptosis. To further elucidate the role of Fas in tumor immune surveillance, we have stably transfected IGR-Heu with a Fas-expression vector and isolated CD95-sensitive and -resistant clones. Our data indicated that the resistance of 2 selected Fas-transfected clones to CD95-mediated lysis correlated with down-regulation of caspase-8 or its lack of cleavage and subsequent activation. All Fas transfectants, either sensitive or resistant to anti-Fas agonistic antibody, were as efficiently lysed by the CTL clone as the parental cell line. In addition, neither anti-Fas-blocking antibody nor Fas-Fc molecule inhibited T-cell lysis of Fas-sensitive tumor clone. This cytotoxicity was extracellular Ca(2+)-dependent and abolished in the presence of EGTA, indicating that it was mainly granzyme-mediated. Interestingly, although the caspase inhibitor z-VAD-fmk had no effect on tumor-cell lysis, it efficiently blocked target DNA damage triggered by autologous CTLs via the granule exocytosis pathway, indicating that the latter event was caspase-dependent. The present results suggest that lung carcinoma-specific CTLs use mainly a granule exocytosis-dependent pathway to lyse autologous target cells and that these effectors are able to circumvent alteration of the Fas-triggered intracellular signalling pathway via activation of a caspase-independent cytoplasmic death mechanism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis*
  • Blotting, Western
  • Carcinoma, Large Cell / immunology
  • Carcinoma, Large Cell / pathology*
  • Carcinoma, Non-Small-Cell Lung / immunology
  • Carcinoma, Non-Small-Cell Lung / pathology*
  • Caspase 8
  • Caspase 9
  • Caspases / metabolism
  • Cytoplasmic Granules / metabolism
  • Exocytosis / physiology*
  • Fas Ligand Protein
  • Flow Cytometry
  • Humans
  • Lung Neoplasms / immunology
  • Lung Neoplasms / pathology*
  • Lymphocytes, Tumor-Infiltrating / immunology*
  • Membrane Glycoproteins / physiology
  • Monitoring, Immunologic
  • Signal Transduction
  • T-Lymphocytes, Cytotoxic / immunology*
  • Transfection
  • Tumor Cells, Cultured
  • fas Receptor / metabolism
  • fas Receptor / physiology*


  • FASLG protein, human
  • Fas Ligand Protein
  • Membrane Glycoproteins
  • fas Receptor
  • CASP8 protein, human
  • CASP9 protein, human
  • Caspase 8
  • Caspase 9
  • Caspases