Benathan M
Department of Dermatology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland.
Br J Dermatol. 1997 Nov;137(5):721-7.
The cellular concentration of reduced glutathione (GSH) modulates the sensitivity of human melanoma cells to alkylating drugs in vitro. To investigate whether the membrane-associated enzyme gamma-glutamyl transpeptidase (gamma-GTP) involved in GSH breakdown was expressed in melanoma cells, the enzymatic activity of gamma-GTP as well as the secretion of GSH were measured in human melanoma cells from four different cell lines (Me8, JUSO, GLL19, Swift). All the cells showed low gamma-GTP activities (0-1 mU/mg protein) and released GSH in culture supernatants at significant rates. After incubation for 24 h in growth medium containing 0.1 mmol/L cystine, the levels of GSH in supernatants ranged from 56 to 111 nmol GSH/mg protein. The GSH metabolism of melanoma cells was also evaluated by measuring the levels of the melanogenesis intermediate 5-S-cysteinyldopa under different experimental conditions. The results of these experiments suggest that melanoma cells have a low ability to metabolize the tripeptide GSH, which appears to be responsible for GSH secretion and accumulation in culture supernatants.
还原型谷胱甘肽（GSH）的细胞浓度可调节人黑色素瘤细胞在体外对烷化剂药物的敏感性。为了研究参与GSH分解的膜相关酶γ-谷氨酰转肽酶（γ-GTP）是否在黑色素瘤细胞中表达，我们测定了来自四种不同细胞系（Me8、JUSO、GLL19、Swift）的人黑色素瘤细胞中γ-GTP的酶活性以及GSH的分泌情况。所有细胞均显示出较低的γ-GTP活性（0-1 mU/mg蛋白质），并以显著速率在培养上清液中释放GSH。在含有0.1 mmol/L胱氨酸的生长培养基中孵育24小时后，上清液中GSH的水平范围为56至111 nmol GSH/mg蛋白质。还通过在不同实验条件下测量黑色素生成中间体5-S-半胱氨酰多巴的水平来评估黑色素瘤细胞的GSH代谢。这些实验结果表明，黑色素瘤细胞代谢三肽GSH的能力较低，这似乎是导致GSH在培养上清液中分泌和积累的原因。
