Insulin inhibits tyrosinase activity and 5-S-cysteinyldopa formation in human melanoma cells.
The effects of insulin on melanogenesis were examined in human Swift melanoma cells. When these cells were grown in a chemically defined culture medium containing insulin (5 microg/ml), they showed a low pigmentation in association with a high activity of glutathione peroxidase (GPO) and a low activity of tyrosinase. In Eagle's minimum essential medium supplemented with foetal calf serum (EMEM-FCS), the Swift cells showed an intense pigmentation in association with a low GPO activity and a high tyrosinase activity. Modulation of GPO activity with sodium selenite had no effect on melanogenesis variables. In contrast, addition of insulin (5 microg/ml) to the EMEM medium led to a marked decrease in tyrosinase activity (p<0.001) and to a concomitant reduction in the levels of 5-S-cysteinyldopa (p <0.01). These results indicate that insulin inhibits the formation of 5-S-cysteinyldopa and that of melanin via the inhibition of tyrosinase activity.
Benathan
M
M
Department of Dermatology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland.
Labidi
F
F
D002118:Calcium / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D003548:Cysteinyldopa / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D008543:Melanins / Q000096:biosynthesis; D008545:Melanoma / Q000378:metabolism*; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D012878:Skin Neoplasms / Q000378:metabolism*; D018038:Sodium Selenite / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D007328:Insulin; D008543:Melanins; D003548:Cysteinyldopa; D005979:Glutathione Peroxidase; D014442:Monophenol Monooxygenase; D005980:Glutathione Reductase; D018038:Sodium Selenite; D002118:Calcium