β-Catenin, Nf-κB and FAS protein expression are independent events in head and neck cancer: study of their association with clinical parameters

In spite of much effort, no good markers have yet been found for predicting prognosis or response to therapy in advanced head and neck squamous cell carcinoma (HNSCCs) patients. β-catenin, a protein involved in the cytoskeleton, cell–cell adhesion and gene transcription, is a factor associated with tumour progression. Recently, an interaction has been reported between β-catenin, and NF-κB coupled with an inverse association of β-catenin, and FAS (CD95/APO-1) protein expression in breast and colorectal tumours. To confirm these observations and to test their clinical impact in HNSCCs we have evaluated the expression of β-catenin, NF-κB and FAS proteins. We used tissue microarrays to simultaneously analyse the levels of these proteins immunohistochemically in 118 HNSCCs. Among the 113 tumours evaluable for β-catenin, increased and decreased levels were detected in 41 (36%) and 62 (55%) of the tumours, respectively. β-catenin, protein staining was mainly membranous but 10 tumours (9%) showed the clear presence of protein in the cytoplasm, and none in the nucleus. Moreover, 81% of the tumours had decreased FAS protein expression, indicating that loss of FAS protein is a common feature of HNSCCs. Abnormal or nuclear NF-κB staining was observed in 24% of the tumours. No association was detected between the expression levels of the proteins evaluated. Regarding clinical associations, tumours from the hypopharynx had significantly lower levels of β-catenin expression than those from other locations (P<0.05). Moreover, our data revealed that patients whose tumours had low levels of β-catenin protein expression had decreased survival probability (24.8 months vs. NR, P=0.03) and reduced response to therapy (15.4 vs. 43 months; P=0.01) compared with patients whose tumours had high levels of β-catenin. Taken together, our observations indicate that β-catenin, NF-κB and FAS expression are independent events during HNSCC development and that levels of β-catenin protein may identify subsets of advanced HNSCCs patients with different prognosis and response to therapy capabilities.