Neural cell adhesion molecule distribution in primary and metastatic uveal melanoma

Tumor cell adhesion, detachment, and aggregation play an important part in tumor invasion and metastasis, and a variety of cell adhesion molecules have been found on tumor cells. Cell adhesion molecules, including those of the immunoglobulin superfamily, are associated with the development of metastatic behavior in cutaneous melanomas. The neural cell adhesion molecule (NCAM) belongs to this family. To investigate its possible role in the development metastatic behavior of uveal melanomas, the authors studied immunohistochemically the expression of NCAM by using an antibody that recognizes all three major isoforms of NCAM and an antibody that recognizes the HNK-1 epitope present on some isoforms of NCAM. The authors studied 32 primary uveal melanomas from 32 patients (among these, 12 were rapidly metastasizing and 16 slowly metastasizing) and 29 metastases from 19 patients. From 13 patients the primary, as well as the metastatic, tumors were available. With one exception, all HNK-1 positive primary and metastatic tumors were also positive for NCAM. NCAM was significantly more expressed in aggressive, rapidly metastasizing primary tumors (P = .02 and .04, respectively) and in metastases. HNK-1 was significantly (P = .04) more expressed in larger tumors. In liver metastases HNK-1 immunoreactivity was significantly (P = .005) less frequently expressed than NCAM. Therefore, NCAM isoforms that lack the HNK-1 epitope might play a role in the organ specific metastatic behavior of uveal melanomas.