Background and Objectives: The EGFR is a member of the erbB family of receptor tyrosine kinase proteins, which also includes HER2/neu (erbB2), HER3 (erbB3), and HER4 (erbB4). High levels of EGFR expression are correlated with poor prognosis and resistance to radiation therapy in a variety of cancers, mostly in head and neck squamous cell carcinoma (HNSCC). So we examined the expression of EGFR in hypopharyngeal cancer and the effect of EGF in progression of hypopharyngeal SCC in the hypopharyngeal SCC cell line (FaDu).
Materials and Methods: We performed immunohistochemical stains on 57 specimens of each normal mucosa and hypopharyngeal SCC with EGFR antibody. For Western blot, fresh normal and cancer tissue from the hypopharynx obtained from three patients were used. We performed RT-PCR and Western blot analyses of FaDu cells. Proliferative of the FaDu cells was assayed by counting the number of the cells after treatment by EGF of different concentration of 0, 10, 30 ng/㎖. Dispersion of the cells was observed by measuring the separation and morphologic changes of the cells after colony of FaDu cells was formed in the media and then was treated with EGF of 10ng/㎖ or 30ng/㎖ for 24 hours. Tumor cell invasiveness was assessed by the membrane invasion assay. RT-PCR and zymography were performed to examine the roles of matrix metalloproteinase-2(MMP-2) and MMP-9, as well as the relationship between EGF and MMPs in FaDu invasiveness.
Results: The positive rates of EGFR expression in hypopharyngeal SCC were 63.2%. EGFR staining was significantly correlated with pathologic stage (p<0.05). The increased expresssion of EGFR mRNA(RT-PCR) and protein (Western Blot) were detected in hypopharyngeal cancer tissue. Exogenous EGF significantly enhanced the growth of FaDu in a dose-dependent manner 30ng/㎖ (p<0.05). EGF markedly enhanced the invasiveness of cancer cells in a Transwell invasion chamber in a dose-dependent manner (p < 0.05). MMP expression was detected in the FaDu cells, and exogenous EGF enhanced the expression and its activity in the RT-PCR and zymogram analysis.
Conclusions: These results suggest that EGF may play an important role in the progression of hypopharyngeal cancer.