Both nevus cells and melanocytes are derived from the neural crest. The etiology of giant congenital nevus cell nevus(GCNN) is thought to be the cloned proliferation of melanoblasts, the precursors of melanocytes, during development and distribution in a restricted area. If the proliferation mechanism is triggered at an early developmental stage, the area of distribution is large and GCNN is produced. Melanocytes, on the other hand, usually migrate into the epidermis and settle there, and they are reported to strongly express E-cadherin during the migration process. Nevus cells, however, are unable to migrate into the epidermis, and many of them remain in the dermis. We used cultured epidermis-derived pigment cells (EDPCs) and cultured dermis-derived pigment cells (DDPCs) obtained from tissues collected from 23 patients with GCNN and investigated the migration of DDPCs in vitro after forced expression of E-cadherin. Immunocytochemistry, Western blotting, and RT-PCR showed that the EDPCs expressed E-cadherin, but the DDPCs did not. An experiment using a Boyden chambershowed that migration of both pigmented cells depends on the presence of E-cadherin. Based on these findings, E-cadherin expression appeared to be necessary for pigment cells to move from the dermis into the epidermis, and cells that express E-cadherin appeared to be capable of moving into epidermis where E-cadherin is expressed.

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