h-89 and scoparone

The effect of coumarin derivatives on melanogenesis was investigated in B16 murine melanoma cells.. Melanin content and tyrosinase activity were analyzed spectrophotometrically. The expression of tyrosinase, tyrosinase-related protein-1 (TRP-1) and tyrosinase-related protein-2 (TRP-2) were measured either by reverse transcription-polymerase chain reaction (RT-PCR) or Western blot.. Among the coumarin derivatives studied, scoparone (6,7- dimethoxycoumarin) was the most potent; the 6- or 7-methoxy group was found to be essential for the stimulation of melanogenesis. The melanin content was greatly increased by scoparone in a dose-dependent manner; there was no cytotoxicity at the effective concentrations. Scoparone increased enzyme activity as well as protein and mRNA expression of tyrosinase. In addition, mRNA of TRP-1 and TRP-2 were also increased after treatment with scoparone. H-89, an inhibitor of protein kinase A (PKA), completely inhibited the scoparone-induced increase of melanogenesis and the tyrosinase protein.. These results suggest that scoparone-induced stimulation of melanogenesis is likely to occur at the transcriptional level of melanogenesis-related enzymes through PKA signaling.

Topics: Animals; Cell Line, Tumor; Coumarins; Cyclic AMP-Dependent Protein Kinases; Dose-Response Relationship, Drug; Intramolecular Oxidoreductases; Isoquinolines; Melanins; Melanoma, Experimental; Membrane Glycoproteins; Mice; Monophenol Monooxygenase; Oxidoreductases; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sulfonamides