[Resistance to Fas-mediated apoptosis in head and neck squamous cell carcinoma cells].
Various types of carcinoma cells have been shown to escape immune recognition by constitutive resistance to Fas receptor (Fas)-mediated apoptosis. The purpose of this study was to examine the sensitivity to Fas-mediated apoptosis of human head and neck squamous cell carcinoma (HNSCC) cells. We applied an anti-Fas monoclonal antibody (CH11) to HNSCC cell lines and monitored their cell death. All three HNSCC cell lines examined expressed Fas protein but not Fas-ligand mRNA. CH11 did not induce cell death (CH11-resistant) in any of the three HNSCC cell lines examined. Treatment with actinomycin D (ActD) converted the phenotypes of the CH11-resistant HNSCC cell lines from CH11-resistant to CH11-sensitive, suggesting that the resistance to CH11-induced apoptosis was dependent on RNA synthesis. Western blot analysis did not show any differences in expression of Bcl-2 between the non-treated and ActD-treated HNSCC cell lines. Expression of Bcl-XL, on the other hand, was greatly reduced in the ActD-treated HNSCC cell lines, implying that Fas signaling in the CH11-resistant HNSCC cell lines might be regulated by an Bcl-XL-inhibitable step.
Otani
Y
Y
Department of Otolaryngology, St. Marianna University School of Medicine, Kanagawa.
Kuwahara
D
D
Tsutsumi
K
K
D017209:Apoptosis; D002294:Carcinoma, Squamous Cell / Q000276:immunology*; D003609:Dactinomycin / Q000494:pharmacology; D006258:Head and Neck Neoplasms / Q000276:immunology*; D006801:Humans; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D014407:Tumor Cells, Cultured; D019014:fas Receptor / Q000235:genetics / Q000276:immunology*
D019384:Nucleic Acid Synthesis Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D019014:fas Receptor; D003609:Dactinomycin