Immunohistochemical study of sialyl Le^a and sialyl Le(x) antigen in oral squamous cell carcinoma: The association of sialyl Le^a expression with the metastatic potential

Background. Carbohydrate antigens in cancer cells are considered to be involved in the binding of cancer cells to the endothelium during metastasis. Methods. Seventy cases of primary oral squamous cell carcinoma (SCC) were obtained from biopsy specimens and were analyzed immunohistochemically using an antibody against sialyl Lewis (Le)^a or sialyl Le(x). Flow cytometry was performed to detect the sialyl Le^a or sialyl Le(x) expressed on oral SCC cell lines. Results. The expressions of sialyl Le^a, but not sialyl Le(x), of primary tumors significantly correlated to nodal metastasis; 71% of the metastatic cases express sialyl Le^a and the cases with positive sialyl Le^a and no sialyl Le(x) demonstrated a high incidence of metastasis (80%). A flow cytometric study demonstrated the oral SCC cell line, which can metastasize in nude mice, to express a high level of sialyl Le^a. Conclusion. The high expression of sialyl Le^a in primary tumors may thus be involved in nodal metastasis and therefore predict a poor prognosis in oral SCC.