ENHANCED SYNTHESIS OF TUMOR NECROSIS FACTOR-INDUCIBLE PROTEINS, PLASMINOGEN-ACTIVATOR INHIBITOR-2, MANGANESE SUPEROXIDE-DISMUTASE, AND PROTEIN 28 5.6, IS SELECTIVELY TRIGGERED BY THE 55-KDA TUMOR-NECROSIS-FACTOR RECEPTOR IN HUMAN-MELANOMA CELLS/

We have demonstrated that A375 melanoma cells express mRNA for both ty pes of tumor necrosis factor (TNF) receptors and receptor proteins on their plasma membranes. Specific agonist and blocking antibodies to ei ther 55-kDa (TNF-R1) or 75-kDa (TNF-R2) TNF receptors combined with tw o-dimensional gel analysis were employed to determine which receptor t ype is responsible for mediating the induction of individual melanoma proteins. Our results indicate that the enhanced synthesis of proteins 21/>7 (M(r)/pI), 28/5.6, and 41/5.7 is selectively induced through TN F-R1. TNF induces these proteins; antagonist antibody to TNF-R1 preven ts their induction by TNF, and TNF-R1 agonist induces them in the abse nce of TNF. Identification of these proteins by immunoblot analysis pr oved that 21/>7 is manganese superoxide dismutase, protein 28/5.6 is u nrelated to 27/28-kDa heat shock protein, and protein 41/5.7 is plasmi nogen activator inhibitor-2. Furthermore, TNF cytotoxicity for A375 ce lls is also mediated by TNF-R1. These studies indicate that TNF-R1 is a critical signaling receptor for TNF action on A375 cells and demonst rate the potential use of TNF-R1 antibodies to selectively block or en hance specific effects of TNF on melanoma cells.