title: Fas ligand promotes tumor immune evasion of colon cancer in vivo.
abstract: The study of the role of Fas ligand (FasL/CD95L) in tumor immune evasion has been complicated by the discovery that FasL may trigger cytokine secretion and induce inflammation. Antisense suppression of FasL expression by colon tumor cells was used to investigate if a reduction in endogenously expressed FasL in tumors resulted in reduced tumor development and improved anti-tumor immune challenge in vivo. Downregulation of FasL expression had no effect on tumor growth in vitro but significantly reduced tumor development in syngeneic immune-competent mice in vivo. Tumor size was also significantly decreased. Reduced FasL expression by tumor cells was associated with increased lymphocyte infiltration. Moreover, constitutively expressed FasL was not pro-inflammatory. This study indicates that upregulation of FasL expression by colon tumor cells results in an improved anti-tumor immune challenge in vivo, providing functional evidence in favor of the 'Fas counterattack' as a mechanism of tumor immune evasion.
authors.affiliation: Department of Medicine, National University of Ireland Cork, Cork, Ireland.
authors.forename: Aideen E
authors.initials: AE
authors.lastname: Ryan
authors.forename: Fergus
authors.initials: F
authors.lastname: Shanahan
authors.forename: Joe
authors.initials: J
authors.lastname: O'Connell
authors.forename: Aileen M
authors.initials: AM
authors.lastname: Houston
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D053222:Fas Ligand Protein / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D016131:Lymphocyte Subsets / Q000276:immunology*; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009368:Neoplasm Transplantation; D020319:Oligodeoxyribonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D014162:Transfection
chemical_list: D053222:Fas Ligand Protein; D020319:Oligodeoxyribonucleotides, Antisense