EXPRESSION OF THE NEUROECTODERMAL INTERMEDIATE FILAMENT NESTIN IN HUMAN MELANOMAS

Nestin is a newly identified intermediate filament expressed in prolif erating neuronal progenitor cells, but not in the adult brain. Nestin expression reappears in many tumors of the central nervous system and has in human glioblastomas been associated with a high degree of malig nancy. Because melanocytes are of neuroectodermal origin, we studied n estin expression in benign and malignant cells of the melanocytic line age using Northern blot and immunohistochemical analyses. Nestin mRNA was detected in 24 of 34 metastatic melanomas and in 1 of 4 benign nev i, whereas the protein was expressed in 10 of 15 primary melanomas, in 29 of 34 metastatic tumors, and in 3 of 4 nevi. Neither normal melano cytes nor any of 4 basal cell carcinomas showed detectable levels of t he protein. The high fraction of melanocytic tumors which express nest in, particularly the metastatic melanomas, suggests that nestin may be a useful marker for such malignancies. Furthermore, although no signi ficant correlation between nestin expression and tumor malignancy was observed, the protein was most abundantly expressed in the infiltratin g part of the tumors, indicating a possible involvement of nestin in t umor invasion.