Background. Sialyl Lewis-x (sLx) is a cellular adhesion molecule (CAM) that has been implicated in the inflammatory reaction and cancer metastasis. The sLx is the carbohydrate ligand of endothelial-selectin (E-selectin), an inducible vascular endothelial CAM. The role of sLx has been investigated in several cancers, and its presence has been correlated with advanced disease stage, decreased disease-free survival, and greater metastatic potential. A recent study has found that cultured head and neck (HN) squamous cell carcinoma (SCC) cell lines express sLx and that binding of these cells to cytokine activated endothelium correlates with the endothelial expression of E-selectin. The purpose of this study was to identify sLx in the tumors of patients with HNSCC and to see if the presence of sLx correlated with disease status.
Methods. We performed immunohistochemical (IHC) staining to detect the sLx antigen using the monoclonal antibody (MAb) KM-93. Eighty-two specimens of HNSCC that were obtained at the time of resection or biopsy were analyzed for sLx staining patterns and intensities. The clinical outcomes of survival, disease-free interval, and incidence of distant metastasis were then assessed to determine whether there was a correlation with sLx tumor expression. In addition, we analyzed specimens from metastatic HNSCC sites for expression of sLx.
Results. The sLx expression was identified in 62% of the primary tumor specimens and 87% of the metastatic tumor specimens analyzed by IHC. The staining pattern in the HNSCC tumors differed from that seen in normal squamous epithelium but was variable in both intensity and distribution. The sLx expression in the metastatic sites was higher than in the primary sites in 67% of the specimens (10 of 15). There was no correlation between sLx staining and disease status.
Conclusions. The results of this study demonstrate that sLx is present in HNSCC and supports the data that show that sLx may play a role in the metastasis of HNSCC. Future studies are warranted to evaluate the role of sLx, E-selectin, and other CAMs in HNSCC.