title: TNF Apoptosis Protection Fraction (TAPF) prevents apoptosis induced by TNF, but not by Fas or TRAIL, via NF-κB-induced increase in cFLIP.
abstract: Tumor Necrosis Factor α (TNFα) induces both the apoptotic pathway and anti-apoptotic factors. Incubation of human dermal fibroblasts with TAPF (TNF Apoptosis Protection Fraction) protects them from apoptosis induced by the subsequent addition of TNF and cycloheximide (CHX). TAPF does not protect against apoptosis induced by CHX in combination with either TRAIL (TNF related apoptosis inducing ligand) or an agonistic Fas antibody, or against apoptosis induced by the chemotherapeutic agent doxorubicin. Incubation with TAPF does not affect the quantity of TNF that binds to the cell. TAPF prevents TNF-induced cleavage of caspases 8, 9, 3 and 7 and the apoptotic substrate PARP (poly-ADP ribose polymerase), but has no effect when these molecules are induced by an agonistic Fas antibody. TAPF induces rapid phosphorylation of the NF-κB/p65 (nuclear factor-κB) transcription factor at serine 536 which is indicative of its activation. TAPF increases the expression of cFLIP (cellular FLICE-inhibitory protein) which is a potent inhibitor of apoptosis that acts by preventing the cleavage of caspase 8. This increase in cFLIP is coincident with protection from TNF-induced apoptosis. Decreasing cFLIP levels using shRNA (short hairpin RNA) decreases protection by TAPF. TAPF also induced the anti-apoptotic A20 protein. These data indicate that TAPF protects human dermal fibroblasts from TNF-induced apoptosis by induction of cFLIP and subsequent inhibition of caspase 8 cleavage.
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA. Electronic address: jseol@yahoo.com.
authors.forename: Ji-Yeon
authors.initials: JY
authors.lastname: Seol
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA. Electronic address: enrico_mihich@dfci.harvard.edu.
authors.forename: Enrico
authors.initials: E
authors.lastname: Mihich
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA. Electronic address: erica.berleth@gmail.com.
authors.forename: Erica S
authors.initials: ES
authors.lastname: Berleth
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology; D006801:Humans; D010766:Phosphorylation / Q000187:drug effects; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D051996:Transcription Factor RelA / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism*
chemical_list: D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C491901:FAS protein, human; C498143:RELA protein, human; D034741:RNA, Small Interfering; C439524:TNF protein, human; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; D004317:Doxorubicin; D003513:Cycloheximide; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3; D053179:Caspase 7; D053181:Caspase 8; D053453:Caspase 9
keywords: Apoptosis; Fas; TNF; TRAIL; cFLIP