Abstract
PURPOSE: The aim of this study was to determine the expression of cellular FLICE-like inhibitory protein (cFLIP) in head and neck squamous cell carcinoma (HNSCC) and revealed its possible correlation to Fas protein and tumour clinical parameters. METHODS: The expression of cFLIP was analysed in 58 HNSCC samples and 30 morphologically normal tissues adjacent to the carcinomas using immunohistochemistry, reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis. Furthermore, its possible correlation to the expression of Fas protein and tumour clinicopathologic parameters were discussed. RESULTS: Cellular FLICE-like inhibitory protein was demonstrated to be up regulated in most HNSCC than in normal tissues by immunohistochemistry (p<0.01). Although the mRNA levels of both isoforms of cFLIP, long form (cFLIP(L)) and short form (cFLIP(S)), in HNSCC were higher than those in normal tissues (p<0.01), only cFLIP(L) protein could be detected by western blot. Furthermore, the expression of cFLIP(L) protein was significantly associated with tumour clinical stage (p<0.01) and lymph node metastasis (p=0.01). Since all of the tumours with Fas immunostaining also express cFLIP protein, there was no significant correlation between them (p>0.05). CONCLUSIONS: Overexpression of cFLIP(L) is a frequent event in HNSCC and HNSCC cells in vivo may need it to evade apoptosis mediated by Fas or other receptors, which might contribute to tumour development and progression.