Liang B C, Ullyatt E
Department of Neurology, University of Colorado Health Sciences Center, Denver 80262, USA.
Clin Cancer Res. 1998 Mar;4(3):773-81.
Recent data have suggested that mitochondria play a supportive role in maintaining the tumorigenic phenotype. Indeed, antimitochondrial agents have been hypothesized to be potential chemosensitizers to human malignancy. We assessed the utility of this approach by characterizing the antimitochondrial activity of 3,5-di-tert-butyl-4-hydroxybenzylidene-malononitrile (AG17), in combination with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) in two human glioblastoma cell lines. AG17 (NSC 242557) is a tyrphostin that has been thought to have some antimitochondrial activity, with limited tyrosine kinase antagonism, and was used at noncytotoxic and nongrowth-inhibitory concentrations (0.25 microM). Glioblastoma cells were incubated in AG17, and changes in mitochondrial activity were determined. Tumor cells became auxotrophically dependent on uridine and pyruvate, indicating the lack of a functioning respiratory chain. Despite this, cells continued to exhibit no growth-inhibitory effects. Exposure to AG17 was associated with significant depolarization of the mitochondrial membrane potential and decreases in mitochondrial mass in both glioblastoma cell lines, correlating with the finding of auxotrophic dependence. In contrast, normal human astrocytes treated with the same dose of AG17 did not show changes in growth, mitochondrial membrane potential, or mass. Indeed, auxotrophic dependence on uridine and pyruvate could not be established in these cells. Glioblastoma cells became significantly more responsive to BCNU chemotherapy with AG17 pretreatment; a linear relationship was noted that correlated the number as well as percentage of polarized mitochondria with glioblastoma cell survival at the highest dose of BCNU used (144 microg/ml). Normal human astrocytes did not change with regard to the dose response to BCNU with previous incubation with AG17. No difference was found in the type of cellular death (apoptosis) in either of the glioblastoma cell lines, with BCNU treatment alone, or with the combination AG17 and BCNU, despite the decrease in polarized mitochondria and mitochondrial mass. AG17 has antimitochondrial properties when used at low dose in human glioblastoma, which are relatively specific to tumor cells when compared with normal astrocytes. The use of AG17 as a chemosensitizer, with drugs such as BCNU, offers a new and possibly effective approach to be developed in patients with glial tumors.
近期数据表明，线粒体在维持肿瘤发生表型方面发挥着支持作用。事实上，抗线粒体药物已被假定为人类恶性肿瘤的潜在化学增敏剂。我们通过在两种人胶质母细胞瘤细胞系中表征3,5 - 二叔丁基 - 4 - 羟基苄叉丙二腈（AG17）与1,3 - 双（2 - 氯乙基）- 1 - 亚硝基脲（BCNU）联合使用时的抗线粒体活性，评估了这种方法的效用。AG17（NSC 242557）是一种酪氨酸激酶抑制剂，被认为具有一定的抗线粒体活性，酪氨酸激酶拮抗作用有限，且以非细胞毒性和非生长抑制浓度（0.25 microM）使用。将胶质母细胞瘤细胞在AG17中孵育，然后测定线粒体活性的变化。肿瘤细胞变得营养缺陷型地依赖尿苷和丙酮酸，这表明呼吸链功能缺失。尽管如此，细胞仍未表现出生长抑制作用。在两种胶质母细胞瘤细胞系中，暴露于AG17均与线粒体膜电位的显著去极化以及线粒体质量的降低相关，这与营养缺陷型依赖性的发现相关。相比之下，用相同剂量的AG17处理的正常人星形胶质细胞在生长、线粒体膜电位或质量方面未显示出变化。实际上，在这些细胞中无法建立对尿苷和丙酮酸的营养缺陷型依赖性。用AG17预处理后，胶质母细胞瘤细胞对BCNU化疗的反应显著增强；在使用的最高剂量BCNU（144 microg/ml）下，观察到极化线粒体的数量和百分比与胶质母细胞瘤细胞存活率之间存在线性关系。在先前用AG17孵育后，正常人星形胶质细胞对BCNU的剂量反应没有变化。在单独使用BCNU或联合使用AG17和BCNU处理的两种胶质母细胞瘤细胞系中，尽管极化线粒体和线粒体质量有所降低，但细胞死亡类型（凋亡）没有差异。当在人胶质母细胞瘤中低剂量使用时，AG17具有抗线粒体特性，与正常星形胶质细胞相比，这些特性相对特异于肿瘤细胞。将AG17与BCNU等药物联合用作化学增敏剂，为胶质肿瘤患者提供了一种新的且可能有效的治疗方法。
