Protein expression of melanocyte growth factors (bFGF, SCF) and their receptors (FGFR‐1, c‐kit) in nevi and melanoma

Abstract

Basic fibroblast growth factor (bFGF) and stem cell factor (SCF) are essential growth factors for melanocytes which carry the receptors FGFR-1 for bFGF and c-kit for SCF. Because both factors may be involved in melanoma development, the expression of bFGF/FGFR-1 and SCF/c-kit was investigated in melanocytic tumors of different progression stages. Fifty primary melanomas and 44 melanocytic nevi were analyzed for the expression of SCF, c-kit, bFGF, and FGFR-1 by immunohistochemistry. In melanoma, SCF and c-kit were expressed in 76 and 84%, respectively, and coexpressed in 66%. bFGF and FGFR-1 were expressed in 45 and 86%, respectively, and coexpressed in 46%. In melanocytic nevi, SCF was expressed in 23% and c-kit in 70% while coexpression was more common in dysplastic (39%) than non-dysplastic subtypes (8%). bFGF and FGFR-1 were expressed in 55 and 67%, respectively, while coexpression was found in 47% but varied considerably between different histological subtypes. SCF and c-kit were frequently expressed by melanomas and dysplastic nevi suggesting an autocrine growth mechanism as described for bFGF. In both nevi and melanoma, c-kit was almost exclusively found in the epidermis while bFGF was more common in the dermis. Thus the growth factor/receptor expression seems to depend on the cutaneous localization of the melanocytic tumors.