BACKGROUND: The regulatory rnechanisrns of melanocytes underlying ultraviolet(UV) melanogenesis have been an interest tu many investigators. They have shown that several materials produced and secreted frorn norm il human keratinocytes play roles as mitogens of human melanocytes, and demonstrated that UVB exposure stirnulated highly the paracrine linkage of endothelin(ET) be tween keratinocytes and melanocytes. It suggest that ET is one of keratinocytes-derived intrinsic mitogens in UVB induced hyperpigmentation. OBJECTIVE: To evaluate whether ET secreted from keratinocytes under the UV irradiation works as paracrine effects such as melanocyte pro)iferation and function, the present, study was under taken. METHODS: Primary kevatinocytes and rnelanocytes cultures from neonatal foreskins were grown in complete MCDB 154 medium. Cultured human keratinocytes were irradiated with UVB 50mJ/ cm2. Twenty fours hour later, conditioned medium of keratinocytes was added into the growth medium of melanocytes of concentration in 10%, 20%, and 30%, respectively. Four days later, in order to detect of melanocytes proliferat.ion and function, number of melanocytes, melanin granules and tyrosinase activity v ere measured. RESULTS: J. The number of me anocytes were higher increase in groups of incubation with conditioned medium of irradiated keratinocytes than that of incubation with conditioned mediurn of irradiated keratinocytes and treatment of anti-ET-1(5ug/ml)(p>0.05). 2. The melanin contents were significantly higher increase in groups of incubation with conditioned medium(20%, 30%) of irradiated keratinocytes than that of incubation with conditioned medium of irradiated keiatinocytes and treatment of anti-ET-1(5ug/ml)(p<0.05). 3. The tyrosinase activity of melanocyte incubated with 30% COllcentration of conditioned medium from cultured keratinocyte irradiated with UVB was significantly higher increase than that of melanocyte incubated with 30% concentration of conditioned mediurn from cultured keratinocytes irradiated with UVB and treated with anti-ET-1(p<0.05). CONCLUSION: This stud provided an important confirmation of the proposal that ET-1 is intrin sic factor for proliferation and differentiation of human melanocytes. These findings suggest that keratinocyte derived ET-1 make a considerable effect on human melanocyte proliferation and function in UV melanog nesis.
Culture Media, Conditioned ; Endothelin-1* ; Foreskin ; Humans* ; Hyperpigmentation ; Keratinocytes* ; Melanins ; Melanocytes* ; Mitogens ; Monophenol Monooxygenase ; Research Personnel