Reactive oxygen species mediate ethaselen-induced rapid apoptosis in A549 cells

活性氧族介导乙烷硒啉在A549细胞中诱导的快速凋亡(英文)

Thioredoxin reductase （TrxR） is an important enzyme responsible for the removal of excess reactive oxygen species （ROS） in mammalian cells. This study aimed to investigate the roles of ROS in the anti-tumor effects of ethaselen, a TrxR inhibitor. In a human lung cancer cell line A549, we observed rapidly elevated ROS levels, loss of mitochondrial potential, and cell death with the treatment of ethaselen. Such changes were prevented when cells were pre-incubated with of N-acetyl-cysteine （NAC）, a ROS scavenger. The apoptosis study by Annexin V-PI assay and protein assay by Western blot suggested that mitochondrial pathway was involved in the initiation of apoptosis. In ethaselen-treated cells, cyclosporin A （CsA）, an inhibitor of mitochondrial permeability transition pores （PTPs）, inhibited the release of cytochrome c and reduced cell death in ethaselen-treated cells, while the protein levels of some Bcl-2 family proteins remained unchanged. These results suggest that ROS mediated the ethaselen-induced rapid apoptosis, at least, partially through the enhancement of mitochondrial membrane permeability, which may ultimately lead to the release of pro-apoptotic proteins. Our study, for the first time, demonstrated that the anti-tumor effects of ethaselen, including the early phase of cellular response, are associated with ROS. More studies are needed to confirm our conclusion, as well as to further explore the underlying mechanisms in the anti-tumor effects of ethaselen.

硫氧还蛋白还原酶(TrxR)是哺乳动物细胞内负责清除过量活性氧族(ROS)的重要酶类。本研究的目的是探究ROS在TrxR抑制剂乙烷硒啉抗肿瘤机制中的作用。在人肺癌细胞A549中,乙烷硒啉迅速诱导ROS含量上升和线粒体膜电位下降,并导致细胞死亡。ROS清除剂N-乙酰半胱氨酸的预孵育可以显著抵抗这三种现象。AnnexinV-PI法和Western blot的结果表明乙烷硒啉激活了内源性凋亡通路。线粒体通透性转变孔道抑制剂环孢菌素A可以抑制乙烷硒啉诱发的细胞色素c释放和细胞死亡,而同时一些Bcl-2家族蛋白含量却没有明显变化。这些结果说明ROS可能部分地通过增加线粒体通透性,释放包括线粒体内的促凋亡因子来介导乙烷硒啉诱发的快速凋亡。首次报道了ROS可能在乙烷硒啉抗肿瘤机制,特别是其早期过程中有重要作用。