Mulcahy R T, Bailey H H, Gipp J J
Department of Human Oncology, University of Wisconsin Medical School, Madison 53792, USA.
Cancer Res. 1995 Nov 1;55(21):4771-5.
Although glutathione (GSH) has long been implicated in resistance to certain common chemotherapeutic agents, including alkylating agents, platinum analogues, and doxorubicin, evidence establishing a direct role in the resistant phenotype has been lacking. We cotransfected COS cells with the cDNAs for the two subunits of gamma-glutamylcysteine synthetase (GCS), which catalyzes the rate-limiting step in the de novo synthesis of GSH and is itself up-regulated in some drug-resistant tumor cells. Transfection resulted in increased GCS activity and elevated GSH levels (up to 2.6-fold). Cotransfection with the two subunits greatly enhanced the synthetic efficiency of the heavy subunit. A direct correlation (P < 0.01) between intracellular GSH levels and the LD99 dose of melphalan was observed, signifying that elevation of the thiol secondary to GCS expression is sufficient to confer the resistance phenotype.
尽管谷胱甘肽（GSH）长期以来被认为与对某些常见化疗药物（包括烷化剂、铂类类似物和阿霉素）的耐药性有关，但一直缺乏能证明其在耐药表型中起直接作用的证据。我们将γ-谷氨酰半胱氨酸合成酶（GCS）的两个亚基的cDNA共转染到COS细胞中，该酶催化GSH从头合成中的限速步骤，并且在一些耐药肿瘤细胞中其自身表达上调。转染导致GCS活性增加和GSH水平升高（高达2.6倍）。两个亚基的共转染极大地提高了重亚基的合成效率。观察到细胞内GSH水平与美法仑的LD99剂量之间存在直接相关性（P < 0.01），这表明GCS表达导致的硫醇升高足以赋予耐药表型。
