Effect of calcipotriol on melanin synthesis by human melanocytes.

Abstract

Objective To investigate the effect of calcipotriol on melanin synthesis by human melanocytes and its possible action mechanism.Methods Primary melanocytes were cultured with various concentrations(10-5,10-6,10-7,10-8,10-9,10-10 mol/L)of calcipotriol for 24 or 48 hours.Subsequently,MTT assay,NaoH assay.Dopa-oxidase assay,Western blot and semiquantitative RT-PCR were used to measure the cell proliferation of,melanin synthesis by.tyrosinase activity,protein and mRNA expression levels in the melanocytes.respectively.Those untreated melanocytes served as the control.Results The calcipotriol between 10-9 and 10-5 mol/L had no significant effect on the proliferation of cultured melanocytes(P＞0.05).while that of 10-9 and 10-8 mol/L increased tyrosinase activity by 137%and 123%,and enhanced melanin synthesis by 40.63%and 18.75%,respectively,compamd with untreated melanocytes(both P＜0.05).Moreover,the tyrosinase protein level increased by 270.4%(P＜0.05)in melanocytes treated with calcipotriol at 10-9 mol/L for 24 hours.The strongest tyrosinase activity and melanin synthesis was observed in melanocytes treated with calcipotriol of 10-9 moI/L.Conclusions The proliferation of melanocytes is unaffected by calcipotriol at 10-9 to 10-5 mol/L,but it can elevate the expression of tyrosinase protein,enhance tyrosinase activity,and promote melanin synthesis in melanocytes. Key words: Melanocytes; Melanins; Calcitriol; Monophenol monooxygenase