Overexpression of cFLIP in head and neck squamous cell carcinoma and its clinicopathologic correlations

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.

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.

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).

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.