The prognostic role of claudins in head and neck squamous cell carcinomas

The expression of tight junction proteins is frequently altered in epithelial cancers. The loss of cell-cell adhesion associates with enhanced metastatic potential, which underlies the role of altered expression pattern of tight junction component claudins (CLDNs). Our study assessed the expression of CLDN 1, 2, 3, 4, 7, 8 and 10 in squamous cell carcinoma of the head and neck region (HNSCC) including oropahrynx, larynx, and hypopharynx in comparison to normal epithelial tissue of the same patient. The surgical samples were examined by tissue microarray and immunohistochemistry, the expression was calculated by H-score, which took account of intensity and percentage of positivity as well. Both normal and cancerous tissue proved negative for CLDN 3, 8 and 10. Normal epithelia showed mild expression of CLDN 4, but the minimal positivity disappeared in squamous cancer. In case of CLDN 1 and CLDN 7 we demonstrated significantly increased intensity in cancer, while CLDN 2 showed decreased expression compared with normal epithelium. The normal polarity and distribution of claudins were lost in HNSCC. Moreover, preserved expression of CLDN 2 (but not that of 1 and 7) was associated with better survival, which suggested a potential prognostic role of CLDN 2.