Selective release of tumor necrosis factor binding protein II by malignant human epidermal cells reveals protection from tumor necrosis factor alpha-mediated cytotoxicity.
Most tumor cells produce both tumor necrosis factor (TNF) receptors, the M(r) 55,000 TNFRI and the M(r) 75,000 TNFRII, but they are mostly resistant to TNF-alpha-induced cytotoxicity. To gain further insight into the escape mechanisms of tumor cells from the harmful effect of TNF-alpha, we investigated the production of TNF-binding proteins (TNF-BPI, TNF-BPII, both M(r) 30,000) by malignant and normal epidermal cells and studied their functional role in TNF-alpha-induced cytotoxicity. Malignant human keratinocytes (A431, KB, HaCaT) and malignant human melanoma cells (KRFM) produced significant levels of both TNF-BPI and TNF-BPII on stimulation with phorbol myristate acetate. In contrast, normal human keratinocytes (HNK) and normal human melanocytes (HNM) released TNF-BPI but not TNF-BPII. The specific production of TNF-BPII in concert with TNF-BPI by the malignant cell lines revealed an inhibitory effect of supernatants on recombinant human TNF-alpha-mediated cytotoxicity of the TNF-dependent murine cell line L929, while supernatants of normal epidermal cells had no effect. Preincubation of supernatants with anti-TNF-BPI monoclonal antibody htr-9 or anti-TNF-BPII monoclonal antibody utr-1 reversed this inhibitory effect additively, indicating that the production of both TNF-BPs is necessary to protect cells from TNF-alpha-mediated cytotoxicity. A TNF-alpha scavanging effect of TNF-BPs resulting in subsequent inhibition of TNF-alpha binding to L929 cells could be demonstrated by ligand blotting and fluorescence-activated cell sorting analysis. Thus the production of TNF-BPII by epidermal tumor cells in concert with TNF-BPI appears to demonstrate a specific mechanism by which malignant epithelial cells escape from TNF-alpha-mediated cytotoxicity.
Department of Special and Environmental Dermatology, University of Vienna, Austria.
P
P
Neuner
G
G
Klosner
M
M
Pourmojib
F
F
Trautinger
R
R
Knobler
D000818:Animals; D000911:Antibodies, Monoclonal; D002352:Carrier Proteins / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism*; D008544:Melanocytes / Q000378:metabolism*; D008545:Melanoma / Q000378:metabolism*; D051379:Mice; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D012878:Skin Neoplasms / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D053319:Tumor Necrosis Factor Decoy Receptors; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D053319:Tumor Necrosis Factor Decoy Receptors; D014409:Tumor Necrosis Factor-alpha; C069521:recombinant human tumor necrosis factor-binding protein-1