Diethylstilbestrol enhances melanogenesis via cAMP-PKA-mediating up-regulation of tyrosinase and MITF in mouse B16 melanoma cells

BackgroundIt is well known that melanin synthesis in melanoma cells is controlled by melanogenic enzymes, which regulate the cAMP-PKA signaling pathway. Estrogen was previously reported to upregulate melanogenesis that is associated with human skin pigmentation.ObjectiveTo investigate the influence and mechanism of diethylstilbestrol (DES) on melanogenesis in mouse B16 melanoma cells.MethodsThe effects of diethylstilbestrol on cell viability, melanin content, tyrosinase activity, cAMP level, expression of the tyrosinase family and microphthalmia related transcription factor (MITF) were measured in B16 melanoma. Estrogen receptor (ER) expression were detected in B16 melanoma and A375 melanoma. Diethylstilbestrol-induced melanin synthesis were evaluated in the presence and absence of H89 (a PKA-specific inhibitor) and ICI182, 780 (a pure ER antagonist). Tyrosinase activity, the mRNA levels of tyrosinase and MITF were evaluated in the presence and absence of H89.ResultsIn B16 cells, diethylstilbestrol increased cell proliferation, melanin synthesis, tyrosinase activity and expression of the tyrosinase family and MITF. ER expression have not difference in human and mouse melanoma. When ER were inhibited by ICI182, 780, DES-induced melanogenesis was significantly reduced. Diethylstilbestrol enhanced the level of cAMP. The upregulation of melanin content and tyrosinase activity stimulated by diethylstilbestrol was significantly attenuated in the presence of H89. Further, diethylstilbestrol-induced upregulation of tyrosinase and MITF were significantly attenuated when the PKA pathway was blocked.ConclusionsDiethylstilbestrol can enhance melanin synthesis in melanoma cells. This effect is associated with activation of the cAMP-PKA pathway and upregulation of expression and activity of the melanogenesis-related enzyme tyrosinase and MITF.

► Diethylstilbestrol increase B16 melanoma cell proliferation, melanin synthesis and tyrosinase’s activity.
► Diethylstilbestrol increased the expressions of both mRNA and proteins of tyrosinase, tyrosinase-related protein and MITF.
► Diethylstilbestrol enhanced the intracellular level of cyclic AMP in B16 cell.
► Diethylstilbestrol induced-melanogenesis was significantly attenuated in the presence of PKA inhibitor.