Glutathione depletion induced by c-Myc downregulation triggers apoptosis on treatment with alkylating agents
Glutathione depletion induced by c-Myc downregulation triggers apoptosis on treatment with alkylating agents
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DOI：
10.1593/neo.03370
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发表时间：
2004-05-01
期刊：
影响因子：
4.8
通讯作者：
Zupi, G
中科院分区：
文献类型：
--
作者：
Biroccio, A;Benassi, B;Zupi, G
在这里，我们研究黑色素瘤细胞 c-Myc 依赖性药物反应所涉及的机制。通过使用三个 M14 衍生的 c-Myc 低表达克隆，我们证明烷化剂顺铂和美法仑会引发 c-Myc 反义转染子的细胞凋亡，但不会引发亲本系的细胞凋亡。相反，无论 c-Myc 表达如何，拓扑异构酶抑制剂阿霉素和喜树碱均以相同程度诱导细胞凋亡。因为我们之前证明 c-Myc 下调会降低谷胱甘肽 (GSH) 含量，所以我们评估了 GSH 在不同药物诱导的细胞凋亡中的作用。在用一种烷化剂或其他烷化剂处理的对照细胞中，通过 L-丁硫氨酸-亚砜亚胺预孵育实现的 GSH 消耗打开了细胞凋亡途径。细胞凋亡通过早期 Bax 重定位、细胞色素 c 释放和伴随的 caspase-9 激活进行，而活性氧的产生和线粒体膜电位的改变是晚期事件。通过将 c-Myc 低表达细胞的细胞内 GSH 含量改变至对照水平，证明 GSH 在 c-Myc 依赖性药物诱导的细胞凋亡中起决定作用。事实上，GSH 乙酯介导的 GSH 增加通过抑制 Bax/细胞色素 c 重新分布消除了顺铂和美法仑诱导的细胞凋亡。还在 M14 Myc 过表达克隆以及黑色素瘤 JR8 c-Myc 反义转染子中评估了 c-Myc、GSH 含量和对烷化剂的反应之间的关系。总之，这些结果表明 GSH 在控制 c-Myc 依赖性药物诱导的细胞凋亡中发挥着关键作用。
Here we investigate the mechanism(s) involved in the c-Myc-dependent drug response of melanoma cells. By using three M14-derived c-Myc low-expressing clones, we demonstrate that alkylating agents, cisplatin and melphalan, trigger apoptosis in the c-Myc antisense transfectants, but not in the parental line. On the contrary, topoisomerase inhibitors, adriamycin and camptothecin, induce apoptosis to the same extent regardless of c-Myc expression. Because we previously demonstrated that c-Myc downregulation decreases glutathione (GSH) content, we evaluated the role of GSH in the apoptosis induced by the different drugs. In control cells treated with one of the alkylating agents or the others, GSH depletion achieved by L-buthionine-sulfoximine preincubation opens the apoptotic pathway. The apoptosis proceeded through early Bax relocalization, cytochrome c release, and concomitant caspase-9 activation, whereas reactive oxygen species production and alteration of mitochondria membrane potential were late events. That GSH was determining in the c-Myc-dependent drug-induced apoptosis was demonstrated by altering the intracellular GSH content of the c-Myc low-expressing cells up to the level of controls. Indeed, GSH ethyl ester-mediated increase of GSH abrogated apoptosis induced by cisplatin and melphalan by inhibition of Bax/cytochrome c redistribution. The relationship among c-Myc, GSH content, and the response to alkylating agent has been also evaluated in the M14 Myc overexpressing clones as well as in the melanoma JR8 c-Myc antisense transfectants. All together, these results demonstrate that GSH plays a key role in governing c-Myc-dependent drug-induced apoptosis.