[Demonstration of polysialic acid and N-CAM in neuroendocrine tumors]

The neural cell adhesion molecule (N-CAM) is a general calcium-independent cell adhesion molecule. A common structural feature of N-CAM is the presence of homopolymers of alpha-2,8-linked sialic acid residues, which regulates the homophilic adhesive properties of N-CAM. N-CAM undergoes a change from a highly sialyated to a less sialylated form from embryonic to adult life. We have investigated the presence of N-CAM, using a monoclonal antibody against polysialic acid, and polyclonal antibodies against N-CAM. We found the presence of highly sialylated N-CAM in pheochromocytomas, medullary carcinomas of the thyroid, neuroblastomas, small cell cancer of lung and pituitary adenomas. We failed to visualize N-CAM in neuroendocrine tumors of various organs (carcinoids), melanomas and pancreatic endocrine tumors. The visualization of polysialic acid and N-CAM could serve as an additional criterium for the differential diagnosis of neuroendocrine tumors.