P252 : Benzo(a)pyrene has effects on the repression of melanogenesis in B16F10 mouse melanoma cells

Background: Benzo(a)pyrene (BaP) is one of the various toxic substances in polluted air. In previous studies, it was reported that BaP accumulates in melanin-containing tissues. However, it remains unclear whether BaP regulates melanogenesis in melanocytes Objectives: We examine the effects of BaP on the melanin synthesis pathway, as well as its effects on the repression of melanogenesis in B16F10 mouse melanoma cell Methods: The melanin content was determined by optical density at 415 nm and normalized to the amount of total protein. We used Western blot with antibodies against MITF, tyrosinase, Tyrp1, Tyrp2 to detect specific proteins. In vitro tyrosinase activity was determined using mushroom tyrosinase. Quantitative real-time PCR was used to determine relative target mRNA expression Results: The mRNA expression of Typ and Tyrp1 were significantly inhibitied in the presence of BaP compared to control メ-MSH treated B16F10 cells. BaP repressed Mitf mRNA and protein expression in メ-MSH treated B16F10 cells. BaP significantly decreased melanin synthesis by Microphthalmia-associated transcription factor-mediated regulation of tyrosinase and tyrosinase-related protein 1 expression in B16F10 mouse melanoma Conclusion: We hypothesize that BaP interrupts the UV protection mechanism by repressing melanin synthesis in the skin, because メ-MSH-induced melanogenesis, the major protection mechanism in UV-exposed skin, is significantly decreased by BaP in B16F10 cells