Effect of Adenosine on Melanogenesis in B16 Cells and Zebrafish

BACKGROUND: Adenosine is a nucleoside, in which an adenine molecule is attached to a ribofuranose sugar moiety. It can be released into the microenvironment by metabolically active cells, and then fulfills a multitude of functions in regulation of cell proliferation, by activating four subtypes of G protein-coupled adenosine receptors. OBJECTIVE: In this study, we investigated the effect of adenosine on melanogenesis, using B16 melanoma cells. METHODS: The toxic effects of adenosine on B16 melanoma cells were assessed. To understand the mechanism of the effect of adenosine on melanogenesis in B16 cells, melanin content and tyrosinase activity were measured. Tyrosinase, tyrosinase-related protein-1, and dopachrome tautomerase were monitored by Western blotting. Finally, adenosine was applied to zebrafish embryos, and its in vivo effect on pigmentation investigated. RESULTS: At a low concentration, adenosine increased melanin content and tyrosinase activity, while a high dose of adenosine resulted in inhibition of tyrosinase activity. Western blotting showed that adenosine increased tyrosinase protein levels slightly, while high-dose adenosine decreased the expression of tyrosinase. In zebrafish tests, adenosine slightly inhibited body pigmentation. CONCLUSION: In this study, we investigated the effect of adenosine on melanogenesis, using the well-established B16 melanoma cell and zebrafish models. The results suggest that adenosine may inhibit pigmentation, through negative regulation of tyrosinase.

Angiolymphoid Hyperplasia with Eosinophilia That Was Possibly Induced by Vaccination in a Child

Angiolymphoid hyperplasia with eosinophilia (ALHE) is a rare benign vasoproliferative disease of an unknown cause involving the skin or subcutaneous tissue of the head and neck, and particularly around the ear. It predominantly affects Caucasian adults during the third and fourth decades and it very rarely occurs in children. We experienced a case of ALHE in a 2-year-old Korean boy who had a firm, pruritic, skin-colored, subcutaneous nodule on his right upper arm. The histopathological findings were compatible with ALHE and they showed prominent vascular changes with epitheloid or histiocytoid endothelial cells surrounded by inflammatory cells, including a large proportion of eosinophils. This unusual distribution of the lesion and the young age of the patient may be associated with vaccination.