Effects of sugars on melanogenesis in cultured melanoma cells

Abstract
A permanent cell line C2M of mouse melanoma B16 was highly melanized in a modified Eagle's MEM supplemented with 10% calf serum, when the medium contained 1 mM galactose and 10 mM pyruvate instead of 5.5 mM glucose. The activity of the key enzyme for melanogenesis, tyrosinase (EC 1.14.18.1), of living cells cultured in the galactose‐pyruvate medium was consistently 27 times higher than that of cells in normal MEM. This high level of tyrosinase activity was maintained in the stationary phase, in contrast to the activity of cells in normal medium, which decreased sharply in the stationary phase. It seems likely that tyrosinase activity is suppressed by the presence of glucose rather than stimulated by galactose. This modified medium should be useful for obtaining a high level of tyrosinase activity in living cells in culture and in cell‐free extracts.