FAS-associated death domain (FADD) is a key adaptor protein that bridges a death receptor (e.g., death receptor 5; DR5) to caspase-8 to form the death-inducing signaling complex during apoptosis. The expression and prognostic impact of FADD in head and neck squamous cell carcinoma (HNSCC) have not been well studied. This study focuses on detecting FADD expression and analyzing its prognostic impact in primary and metastatic HNSCCs. We found a significant increase in FADD expression in primary tumors with lymph node metastasis (LNM) in comparison with primary tumors with no LNM. This increase was significantly less in the matched LNM tissues. Both univariate and multivariable analyses indicated that lower FADD expression was significantly associated with better disease-free survival and overall survival in HNSCC patients with LNM although FADD expression did not significantly affect survival of HNSCC patients without LNM . When combined with DR5 or caspase-8 expression, patients with LNM expressing both low FADD and DR5 or both low FADD and caspase-8 had significantly better prognosis than those expressing both high FADD and DR5 or both high FADD and caspase-8. However, the expression of both low FADD and caspase-8 was significantly linked to worse overall survival compared with both high FADD and caspase-8 expression in HNSCC patients without LNM. Hence, we suggest that FADD alone or together with DR5 and caspase-8 participates in metastatic process of HNSCC.
Keywords: FADD; caspase-8; death receptor 5; head and neck cancer; immunohistochemistry.