c-FLIP expression in bladder urothelial carcinomas: its role in resistance to Fas-mediated apoptosis and clinicopathologic correlations.
OBJECTIVE
To investigate the incidence of Fas (exon 9) mutations and the expression of Fas, Fas-Fas ligand (FasL) system, and cellular FLICE-like inhibitory protein (c-FLIP) in relation to standard clinicopathologic parameters and patient outcome in bladder carcinoma. Disruption of apoptotic cell death has been implicated in tumor aggressiveness in bladder urothelial carcinomas. The FasL system is involved in the execution of apoptosis induced by the immune system. c-FLIP protein constitutes an important endogenous inhibitor of Fas and other death receptor-mediated apoptosis.


METHODS
The expression of Fas, FasL, and c-FLIP was quantified immunohistochemically in paraffin-embedded tissues from 53 patients for whom clinical information was available. DNA extracted from the same samples was screened for mutations in Fas exon 9 by single-strand conformation polymorphism and sequencing. The effect of Fas, FasL, and c-FLIP on clinical outcome was assessed by univariate and multivariate analyses.


RESULTS
Positive immunostaining was detected for Fas, FasL, and c-FLIP in 72%, 66%, and 81% of cases, respectively. Concurrent expression of Fas and FasL was seen in 27 samples (51%), of which 22 (81.5%) also displayed c-FLIP positivity. FasL and c-FLIP expression increased with advancing stage but was absent from normal urothelium. None of the 53 urothelial carcinoma samples analyzed showed evidence of mutations by polymerase chain reaction single-strand conformation polymorphism and direct sequencing. Survival analysis demonstrated that although both FasL and c-FLIP expression adversely affected survival, only c-FLIP remained statistically significant on multivariate analysis.


CONCLUSIONS
The frequent expression and coexpression of Fas, FasL, and c-FLIP in urothelial carcinomas implicates c-FLIP as an inhibitor of the Fas-FasL-induced death pathway in these tumors. Moreover, c-FLIP conveys independent prognostic information in the presence of classical prognosticators.
Korkolopoulou
Penelope
P
Department of Pathology, National and Kapodistrian University of Athens Medical School, Athens, Greece.
Goudopoulou
Athina
A
Voutsinas
Gerassimos
G
Thomas-Tsagli
Euphemia
E
Kapralos
Panagiotis
P
Patsouris
Efstratios
E
Saetta
Angelica A
AA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002277:Carcinoma / Q000378:metabolism / Q000473:pathology; D002352:Carrier Proteins / Q000378:metabolism*; D053222:Fas Ligand Protein; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D015999:Multivariate Analysis; D009154:Mutation; D009361:Neoplasm Invasiveness / Q000503:physiopathology*; D009367:Neoplasm Staging; D011506:Proteins / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor; D016019:Survival Analysis; D001749:Urinary Bladder Neoplasms / Q000378:metabolism* / Q000473:pathology*; D019014:fas Receptor
D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; C491901:FAS protein, human; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D011506:Proteins; D018124:Receptors, Tumor Necrosis Factor; D019014:fas Receptor