High level of cFLIP correlates with resistance to death receptor-induced apoptosis in bladder carcinoma cells.
BACKGROUND
The cellular form of FLICE-inhibitory protein (cFLIP) blocks death receptor-induced apoptosis and has been implicated in tumour progression. cFLIP interacts with caspase-8, thereby preventing activation of the caspase cascade. In this study we investigated the endogenous expression of cFLIP and caspase-8 in bladder carcinoma cells in relation to their sensitivity to death receptor-ligation.


METHODS
Apoptosis was induced by agonistic anti-CD95 mAbs or recombinant TRAIL and quantified by the TUNEL technique. The relative mRNA expression of cFLIP and caspase-8 was quantified by real-time PCR. Stable expression of cFLIP long (cFLIPL) was obtained by retroviral transduction.


RESULTS
The relative ratio of cFLIP and caspase-8 was directly correlated to resistance to anti-CD95 or TRAIL-mediated apoptosis. Overexpression of cFLIPL shifted the responsiveness towards resistant status.


CONCLUSIONS
cFLIP is an important determinant of susceptibility to death receptor-induced apoptosis in bladder carcinomas and could function as a prognostic marker for death receptor sensitivity in future immune therapy.
Jönsson
Gun
G
Department of Immunology, Wenner-Gren Institute, Stockholm University, S-106 91 Stockholm, Sweden. gun@imm2.su.se
Paulie
Staffan
S
Grandien
Alf
A
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002277:Carcinoma / Q000378:metabolism / Q000473:pathology*; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D019008:Drug Resistance, Neoplasm; D004790:Enzyme Induction; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020287:In Situ Nick-End Labeling; D047908:Intracellular Signaling Peptides and Proteins; D019169:Jurkat Cells / Q000378:metabolism / Q000473:pathology; D008562:Membrane Glycoproteins / Q000494:pharmacology; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000187:drug effects / Q000502:physiology*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D001749:Urinary Bladder Neoplasms / Q000378:metabolism / Q000473:pathology*; D019014:fas Receptor / Q000187:drug effects / Q000502:physiology*
D000911:Antibodies, Monoclonal; D051017:Apoptosis Regulatory Proteins; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases