探討甲型硫辛酸對B16-F1黑色素瘤細胞中eumelanin生合成相關基因表現之影響

已知TRP1和TRP2是黑色素細胞中eumelanin生成過程之重要酵素，且二者之表現受上游基因Mitf的活化而向上調控。又已知甲型硫辛酸會藉由調控細胞中麩胱甘肽含量，使B16-F1黑色素瘤細胞內外之eumelanin生合成降低，並減少細胞內、外黑色素含量，因此，本實驗主要探討(1)不同濃度甲型硫辛酸處理B16-F1黑色素瘤細胞72小時後，對細胞內、外黑色素生合成之影響。(2)以西方墨點分析法檢測不同濃度甲型硫辛酸處理B16-F1黑色素瘤細胞72小時後，對細胞中eumelanin生合成相關基因，包括TRP1、TRP2、Mitf表現之影響。實驗結果發現：(1)隨著甲型硫辛酸濃度增加，會減少B16-F1黑色素瘤細胞內、外黑色素含量。(2) 400μM甲型硫辛酸之處理會降低B16-F1黑色素瘤細胞中TRP2及Mitf之表現量，然而對TRP1之表現則無明顯影響。顯示甲型硫辛酸可能藉由抑制Mitf的表現，進而抑制下游基因TRP2之表現，使 B16-F1黑色素瘤細胞內、外黑色素含量降低。

It has been confirmed that TRP1 and TRP2 are the important enzymes involved in eumelanogenesis of melanocytes, and the expressions of TRP1 and TRP2 genes are up-regulated by activation of upstream gene, Mitf. Alpha-Lipoic acid decreased eumelanogenesis by regulating the glutathione content in cells, and reduced the intra/ extracellular melanin content of B16-F1 melanoma cells. Therefore, our study was to evaluate (1) the intra/extracellular melanin biosynthesis of B16-F1 melanoma cells when treated with different concentrations of Alpha-lipoic acid at 72 hours, (2) the expressions of eumelanogenesis related genes, including TRP1, TRP2 and Mitf of B16-F1 melanoma cells when treated with different concentrations of Alpha-lipoic acid at 72 hours. Our results has shown that (1) the intra/extracellular melanin content were decreased by increasing the concentrations of Alpha-lipoic acid. (2) 400μM Alpha-lipoic acid also reduced the expressions of TRP2 and Mitf of B16-F1 melanoma cells, but TRP1 expression remained unchanged. The results suggested that Alpha-lipoic acid inhibited the expression of Mitf, and further inhibited the expression of a downstream gene, TRP2, to decrease intra/ extracellular melanin content of B16-F1 melanoma cells.