Burrow S M, Phoenix D A, Wainwright M, Waring J J
Department of Biological Sciences, University of Central Lancashire, Preston, UK.
Membr Cell Biol. 2000;14(3):357-66.
Victoria Blue BO (VBBO) is thought to exert its photocytotoxic effects via free radical generation. Glutathione and related enzymes are associated with the protection of normal tissues against free-radical damage and have also been implicated in multiple drug resistance. It might, therefore, be expected that cells containing higher levels of glutathione would be resistant to the cytotoxic effects of VBBO. The total glutathione content for a murine mammary tumour cell line, EMT6-S, was found to be lower than in a multi-drug resistant cell line, EMT6-R, 21.84+/-2.54 microg (mg protein)(-1) and 18.79+/-2.7 microg (mg protein)(-1), respectively; however, this was not found to be a significant difference (p > 0.05, Student t-test). Buthionine sulfoximine, a potent inhibitor of gamma-glutamyl cysteine synthetase, brought about a reduction in glutathione levels in both EMT6-S and EMT6-R cell lines in a concentration-dependent manner. Buthionine sulfoximine administration was effective in reducing intracellular glutathione levels by up to 90% in both types of cells. Interestingly, glutathione depletion of EMT6-S and EMT6-R cells did not enhance the photocytotoxic effect of VBBO, suggesting that the primary site of action of VBBO may be at an intracellular site not protected by glutathione or that the mechanism of action is not via the in situ generation of free radical species.
维多利亚蓝BO（VBBO）被认为是通过产生自由基发挥其光细胞毒性作用。谷胱甘肽及相关酶与保护正常组织免受自由基损伤有关，并且也与多药耐药性有关。因此，可以预期，谷胱甘肽水平较高的细胞会对VBBO的细胞毒性作用产生抗性。发现一种小鼠乳腺肿瘤细胞系EMT6 - S的总谷胱甘肽含量低于一种多药耐药细胞系EMT6 - R，分别为21.84±2.54微克/（毫克蛋白）⁻¹和18.79±2.7微克/（毫克蛋白）⁻¹；然而，未发现这是显著差异（p＞0.05，学生t检验）。丁硫氨酸亚砜胺，一种γ-谷氨酰半胱氨酸合成酶的有效抑制剂，以浓度依赖的方式使EMT6 - S和EMT6 - R细胞系中的谷胱甘肽水平降低。给予丁硫氨酸亚砜胺在两种类型的细胞中均能有效将细胞内谷胱甘肽水平降低达90%。有趣的是，EMT6 - S和EMT6 - R细胞的谷胱甘肽耗竭并未增强VBBO的光细胞毒性作用，这表明VBBO的主要作用位点可能在细胞内不受谷胱甘肽保护的部位，或者其作用机制不是通过原位产生自由基。
