Benathan M, Alvero-Jackson H, Mooy A M, Scaletta C, Frenk E
Department of Dermatology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
Melanoma Res. 1992 Dec;2(5-6):305-14. doi: 10.1097/00008390-199212000-00003.
Resistance to alkylating agents has been correlated with cellular levels of reduced glutathione (GSH) and glutathione-S-transferase (GST). GSH is also involved in regulation of melanin synthesis. Therefore, we examined sensitivity to melphalan as a function of differentiation and GSH/GST levels in three human melanoma cell lines. The Me8 cell line, classified as undifferentiated on the basis of cell shape, absence of pigment, insignificant dopa oxidase activity and presence of inhibitors of dopa-melanin formation, showed the lowest GST activity among the cell lines investigated. GLL19 cells exhibited normal differentiation as indicated by the presence of dendrites, typical eumelanosomes, melanin granules and dopa oxidase activity. These cells showed the highest GSH content and the highest GST activity. The JUSO cell line showed incomplete differentiation, and its dopa oxidase and GST activities were intermediate between the Me8 and GLL19 cell lines. The sensitivity of melanoma cell lines to melphalan increased with their degree of differentiation; it was lowest for Me8, intermediate for JUSO and highest for GLL19. Dibutyryl cyclic AMP (dbcAMP) enhanced melphalan toxicity against Me8 cells. Depletion of intracellular GSH with buthionine sulphoximine (BSO) resulted in a three-fold increase in melphalan sensitivity in all three cell lines. Our results indicate that melphalan toxicity is related to cell differentiation and GSH status of melanoma cells. Based on the observed relationship between dopa oxidase, GSH/GST levels and drug toxicity, it is proposed that competition for the GSH pool between quinonoid melanin intermediates and melphalan could diminish drug conjugation and increase cytotoxicity.
对烷化剂的耐药性与细胞内还原型谷胱甘肽（GSH）和谷胱甘肽-S-转移酶（GST）的水平相关。GSH还参与黑色素合成的调节。因此，我们研究了三种人黑色素瘤细胞系中马法兰敏感性与分化及GSH/GST水平之间的关系。根据细胞形态、无色素、多巴氧化酶活性不显著以及存在多巴-黑色素形成抑制剂，Me8细胞系被归类为未分化细胞系，在所研究的细胞系中其GST活性最低。GLL19细胞表现出正常分化，有树突、典型的真黑素小体、黑色素颗粒和多巴氧化酶活性。这些细胞显示出最高的GSH含量和最高的GST活性。JUSO细胞系表现出不完全分化，其多巴氧化酶和GST活性介于Me8和GLL19细胞系之间。黑色素瘤细胞系对马法兰的敏感性随其分化程度增加而增加；Me8最低，JUSO中等，GLL19最高。二丁酰环磷腺苷（dbcAMP）增强了马法兰对Me8细胞的毒性。用丁硫氨酸亚砜胺（BSO）耗尽细胞内GSH导致所有三种细胞系对马法兰的敏感性增加了三倍。我们的结果表明，马法兰毒性与黑色素瘤细胞的细胞分化和GSH状态有关。基于观察到的多巴氧化酶、GSH/GST水平与药物毒性之间的关系，有人提出醌类黑色素中间体与马法兰之间对GSH池的竞争可能会减少药物结合并增加细胞毒性。
