Targeting Tumor Cell Iron Addiction to Achieve Tumor-Selective Cell Death

项目摘要/摘要 肿瘤细胞对高水平的过渡元素铁上瘾，这是发挥肿瘤细胞功能所必需的。 能使肿瘤细胞快速分裂和生长的铁依赖酶。当隔离不当时，铁 具有高度的氧化还原活性，可以催化形成有毒的活性氧物种，从而破坏细胞。它 因此，应该可以通过释放这种氧化还原活性来选择性地杀死肿瘤细胞 元素。RAS-RAF-MEK通路激活在许多癌症中是一种常见事件，目前难以 用现有的药物治疗。我们之前发现了几种小分子化合物，它们可以选择性地杀死一种 在这一途径中具有激活突变的多种人类肿瘤细胞。这些RAS选择性致死(RSL) 化合物似乎引发了一种新的细胞死亡形式，这种形式利用了在细胞内发现的高水平的铁 这些肿瘤细胞。在这里，我将重点放在一种RSL的致死机制上，Erastin。使用RNA干扰(RNAi) 筛选I确定了11个与Erastin诱导死亡有关的基因，其中包括未鉴定的基因ACSF2。 我假设ACSF2调节一种铁结合分子(铁载体)的产生，这是必要的 对于肿瘤细胞的快速增殖和erastin的致死作用，通过调节胞质铁水平和 血红素依赖的NADPH氧化酶1(NOX1)复合体活性。我将在人类肿瘤细胞中测试这一假说 在Acsf2基因敲除小鼠中，使用遗传、生化和化学方法检测细胞死亡、铁代谢、 NOx活性、铁载体生成与移植瘤生长。这项工作将定义小说《细胞死亡》 由erastin和类似化合物触发的途径，为铁载体介导的铁的作用提供了洞察力 摄取肿瘤细胞生长并显著提高我们靶向细胞铁成瘾的能力 RAS途径突变癌症中的肿瘤选择性细胞死亡。

Project Summary/Abstract Tumor cells are 'addicted' to high levels of the transition element iron, which is necessary for the function of iron-dependent enzymes that enable rapid tumor cell division and growth. When improperly sequestered, iron is highly redox active and can catalyze the formation of toxic reactive oxygen species that destroy the cell. It should therefore be possible to kill tumor cells in a selective way by unleashing the redox activity of this element. RAS-RAF-MEK pathway activation is a common event in many cancers that is currently difficult to treat with existing drugs. We previously identified several small molecule compounds that selectively kill a variety of human tumor cells with activating mutations in this pathway. These RAS-selective lethal (RSL) compounds appear to trigger a new form of cell death that exploits the high levels of intracellular iron found in these tumor cells. Here I focus on the lethal mechanism of one RSL, erastin. Using RNA interference (RNAi) screening I identified 11 genes required for erastin-induced death, including the uncharacterized gene ACSF2. I hypothesize that ACSF2 regulates the production of an iron-binding molecule (siderophore) that is necessary for rapid tumor cell proliferation and for the lethal effects of erastin, via regulation of cytosolic iron levels and heme-dependent NADPH oxidase 1 (NOX1) complex activity. I will test this hypothesis in human tumor cells and in Acsf2 knockout mice using genetic, biochemical and chemical assays of cell death, iron metabolism, NOX activity, siderophore production and xenograft tumor growth. This work will define the novel cell death pathway triggered by erastin and similar compounds, provide insight into the role of siderophore-mediated iron uptake in tumor cell growth and significantly improve our ability to target cellular iron addiction to achieve tumor-selective cell death in RAS pathway mutant cancers.