c-FLIP expression in colorectal carcinomas: association with Fas/FasL expression and prognostic implications.

AIMS: Disruption of apoptotic cell death has been implicated in tumour aggressiveness in colonic carcinogenesis. The Fas-Fas ligand (FasL) system is involved in the execution of apoptosis induced by the immune system. c-FLIP protein constitutes an inhibitor of Fas and other (TRAIL) death receptor-mediated apoptosis. The aim of this study was to investigate the simultaneous expression of Fas, FasL and c-FLIP in relation to standard clinicopathological parameters and patients' outcome in colorectal cancer. METHODS AND RESULTS: Levels of Fas, FasL and c-FLIP protein expression were quantified immunohistochemically in paraffin-embedded tissues from 90 patients. Immunopositivity was detected for Fas, FasL and c-FLIP in 71%, 35.5% and 68.8% of cases, respectively. Concurrent expression of Fas/FasL was seen in 28 samples (31%), of which 24 (85.7%) also displayed c-FLIP positivity (P = 0.04). c-FLIP overexpression (> 10%) tended to prevail marginally in higher stage tumours (P = 0.09). Additionally, FasL and c-FLIP adversely affected survival on both univariate (P = 0.001 and P = 0.0024, respectively) and multivariate analysis [hazard ratio (HR) 3.491, P = 0.005 and HR 2.960, P = 0.036, respectively]. CONCLUSIONS: The frequent expression and coexpression of Fas, FasL and c-FLIP in colorectal carcinoma implicates c-FLIP as an inhibitor of the Fas-FasL-induced death pathway in these tumours. Moreover, c-FLIP conveys independent prognostic information in the presence of classical prognosticators.

Microsatellite instability in sporadic and inherited colon adenocarcinomas from Greek patients: correlation with several clinicopathological characteristics.

BACKGROUND AND AIMS: Microsatellite instability seems to play a significant role in colorectal carcinogenesis, as it is reported to occur in HNPCC patients as well as in a proportion of sporadic cases. The aim of this study was to examine the presence of microsatellite instability in relation to other commonly observed genetic abnormalities and clinicopathological characteristics of sporadic and inherited colorectal cancers. METHODOLOGY: One hundred and three sporadic colorectal adenocarcinomas and 9 adenocarcinomas from HNPCC patients were histologically evaluated. The presence of microsatellite instability was investigated at six loci. K-ras and p53 mutations, p53 LOH, hMLH1 expression and methylation status were examined as well. Statistical analysis was performed to define possible correlations of the observed genetic alterations with the clinicopathological characteristics of the analysed tumors. RESULTS: High-grade microsatellite instability was found in 14% of sporadic adenocarcinomas and in 78% of adenocarcinomas from HNPCC patients. K-ras and p53 mutations were found in 29% and 28% of sporadic adenocarcinomas respectively and in 0% and 22% of the 9 HNPCC cases. A statistically significant correlation was noticed in sporadic tumors between the presence of MSI-H and tumor location at the proximal colon, as well as with the female gender. CONCLUSIONS: Sporadic MSI+ colon adenocarcinomas seem to represent a distinct entity with a unique profile of genetic changes, different from those observed in HNPCC or MSI negative sporadic tumors.