Abstract: Objective To explore the regulatory mechanism of tyrosinase activity by cAMP/PKA dependent signaling pathway. Methods The regulatory effects on tyrosinase mRNA level were assessed by forskolin, a specific activator of adenylate cyclase in cultured B16F10 murine melanoma cells by using RT-PCR technique. Results It was shown that forskolin could significantly enhance tyrosinase activity, melanin content, and tyrosinase mRNA level. Tyrosinase activity and melanin content were as much as seven to ten-fold higher in cells exposed simultaneously to forskolin and 8-MOP than those in untreated cells. The levels of tyrosinase mRNA were up-regulated by 26.06% with 8-MOP, 6.58% with forskolin, and 56.82% with 8-MOP plus forskolin, respectively. Conclusion Forskolin is shown to enhance 8-MOP-induced tyrosinase activity, probably by way of up-regulation of tyrosinase mRNA expression and tyrosinase synthesis. Further study is needed to understand the therapeutic significance of forskolin for vitiligo.

Key words: Monophenol monooxygenase, Cyclic AMP-dependent protein kinases, Gene expression, Methoxsalen