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

项目总结/摘要 肿瘤细胞对高水平的过渡元素铁“上瘾”，这是肿瘤细胞功能所必需的。 铁依赖性酶，使肿瘤细胞快速分裂和生长。如果隔离不当，铁 是高度氧化还原活性的，并且可以催化破坏细胞的有毒活性氧物质的形成。它 因此，应该有可能以选择性的方式杀死肿瘤细胞，通过释放这种氧化还原活性， 元素RAS-RAF-MEK通路活化是目前难以识别的许多癌症中的常见事件。 用现有的药物治疗。我们以前发现了几种小分子化合物，可以选择性地杀死 在该途径中具有激活突变的各种人类肿瘤细胞。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，这种死亡利用了在细胞内发现的高水平的细胞内铁。 这些肿瘤细胞。在这里，我专注于一个RSL的致命机制，erastin。RNA干扰（RNAi） 筛选I鉴定了erastin诱导的死亡所需的11个基因，包括未表征的基因ACSF 2。 我假设ACSF 2调节铁结合分子（铁载体）的产生， 通过调节胞浆铁水平， 血红素依赖性NADPH氧化酶1（NOX 1）复合物活性。我将在人类肿瘤细胞中检验这一假设 以及在Acsf2敲除小鼠中使用细胞死亡，铁代谢， NOX活性、铁载体产生和异种移植肿瘤生长。这项工作将定义新的细胞死亡 由erastin和类似化合物触发的途径，提供了对铁载体介导的铁的作用的深入了解 肿瘤细胞生长中的吸收，并显着提高我们针对细胞铁成瘾实现的能力 RAS通路突变型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.