Steel Factor is Involved in Regulating the Proliferation and Differentiation of Cultured Epidermal Melanocytes From UVB-Induced Pigmented Spots in the Dorsal Skin of Hairless Mice

Long-term exposure to ultraviolet radiation B (UVB) is known to induce pigmented spots in the dorsal skin of hairless mice. It has been shown that the proliferation of epidermal melanoblasts and melanocytes from UVB-induced pigmented spots is greatly stimulated, and the stimulation is regulated by keratinocytes rather than melanocytes by using a serum-free culture system supplemented with dibutyryl adenosine 3\u27:5\u27-cyclic monophosphate and basic fibroblast growth factor. In this study, to understand what factors derived from keratinocytes are involved in regulating the proliferation and differentiation of epidermal melanoblasts and melanocytes from UVB-induced pigmented spots, a lot of antibodies against growth factors and cytokines were supplemented to the serum-free culture medium in the presence of keratinocytes. Results showed that antibody against steel factor (SLF) inhibited the proliferation and differentiation of cultured epidermal melanoblasts / melanocytes from UVB-induced pigmented spots of hairless mice. But not from non-irradiated mice. In contrast, antibodies against hepatocyte growth factor and leukemia growth factor failed to affect the proliferation and differentiation of cultured epidermal melanoblasts / melanocytes from both control and irradiated mice. These results suggest that SLF is one of the keratinocyte-derived factors and involved in regulating the proliferation and differentiation of epidermal melanoblasts / melanocytes from UVB-induced pigmented spots in the dorsal skin of hairless mice.第18回国際色素細胞学