RESUMO
Previous studies have demonstrated that approximately 30% of squamous cell carcinoma of the head and neck (SCCHN) cell lines express high levels of interleukin-13 receptor(s) (IL-13R). However, the incidence, expression level, and significance of IL-13R expression in human tumor specimens is not known. In addition, it is not known whether normal head and neck tissues express IL-13R. In this study, we evaluated the expression of IL-13R subunits (IL-13Ralpha1, IL-13Ralpha2, and IL-4Ralpha) in 337 surgically excised specimens of SCCHN and normal head and neck tissues. Specimens were obtained from 139 patients with SCCHN and 16 patients with benign tonsil disorders from two centers in the United States and Japan and evaluated with immunohistochemistry and in situ hybridization. Extensive analysis demonstrated that the majority of SCCHN tumors uniformly expressed low levels of IL-13Ralpha1 chain; however, 77% of the tumors expressed moderate to high levels of IL-4Ralpha, which forms a signaling complex with IL-13Ralpha1 chain. On the other hand, 33% of SCCHN tumors expressed moderate to high levels of IL-13Ralpha2 chain. Using tissue array from 99 patients, we observed that the expression levels of IL-13Ralpha2 and IL-4Ralpha were significantly higher in SCCHN than in normal head and neck tissues (P < 0.005). Detailed analysis of clinicopathological features demonstrated a positive statistically significant correlation between IL-13Ralpha2 expression and clinically advanced primary SCCHN tumor (T(4); Tumor-Node-Metastasis classification; P < 0.05). However, there was no correlation among IL-13R expression and sex, age of patients, stage of lymph node metastasis, squamous cell carcinoma grade, or allergic history. Taken together, this study suggests that IL-13R may be involved in SCCHN tumor progression, and 33% of IL-13Ralpha2-positive SCCHN cases may be targeted by IL-13 cytotoxin and IL-13R-targeted agent.