Effect of kappa elastin on melanogenesis in A375 human melanoma cells and its related mechanism.

BACKGROUND: Elastin derived peptides can regulate melanocyte precursor development. Ultraviolet irradiation, infrared radiation and heat can increase the synthesis of tropoelastin in human skin epidermis. The aim of this study was to investigate whether the over expressed tropoelastin in epidermis has some role in melanogenesis of melanocytes. METHODS: A375 human melanoma cells were treated with different concentrations of kappa elastin for 24 hours. A375 human melanoma cells were randomly assigned to control, kappa elastin, and lactose pre-incubated groups. The cell viabilities were detected by the methyl thiazoleterazolium assay. Melanin content and tyrosinase activity in A375 melanoma cells were measured. The expressions of endothelin B receptor (ET(B)R) mRNA and c-kit mRNA in A375 melanoma cells were measured by quantative reverse transcription polymerase chain reaction. RESULTS: Fifty µg/ml of kappa elastin significantly increased the melanin content by 56.64% compared with the control (P < 0.05). Kappa elastin increased cellular tyrosinase activity by 46.73% compared with the control at 24 hours (P < 0.05). Kappa elastin increased the expressions of ET(B)R and c-kit mRNA levels by 2.13-fold and 2.47-fold compared with the controls, respectively. When pre-incubating cells with a lactose solution (10 mmol/L), the inhibition on melanin production was 34.96% compared with the kappa elastin group (P < 0.05), tyrosinase activity was inhibited by 29.93% compared with kappa elastin group (P < 0.05), and the expressions of ET(B)R mRNA and c-kit mRNA were decreased by 1.56-fold and 0.82-fold compared with kappa elastin group, respectively. CONCLUSION: Kappa elastin increased the melanogenesis in A375 melanoma cells via the stimulation of tyrosinase activity and the expression of ET(B)R and c-kit. The over expressed tropoelastin produced by keratinocytes might play a role in melanogenesis of epidermal melanocytes.