The role of mitochondrial glutathione homeostasis in tumor formation

项目摘要 癌细胞需要大量的抗氧化能力来克服活性氧的毒性作用 （ROS）。尽管它们只在胞浆中产生，但细胞抗氧化剂也大量存在于细胞中。 细胞器，特别是线粒体。特别是线粒体，作为活性氧的来源， (ROS)，需要大量的抗氧化剂来保护其关键的氧化还原功能。虽然以前的工作 提示线粒体氧化还原代谢和肿瘤生长之间的联系， 维持线粒体氧化还原稳态和线粒体抗氧化剂在肿瘤进展中的作用 我们对此知之甚少。在内源性线粒体抗氧化剂中，谷胱甘肽（GSH）是主要的小分子抗氧化剂。 分子硫醇，以毫摩尔浓度存在。GSH通常在癌细胞中上调， 转移定植和对化疗药物的抗性。在我们以前的工作中，使用生物化学和 利用蛋白质组学方法，我们鉴定了SLC25A39，一个功能未知的线粒体膜载体， 介导GSH输入到癌细胞的线粒体中。SLC25A39缺失强烈降低线粒体GSH 水平及其进口，而不影响那些在胞质溶胶。我们的初步工作表明，SLC25A39 表达与乳腺癌患者的预后不良和生存率降低相关， SLC25A39是乳腺癌侵袭和转移所必需的。这一发现给了我们机会， 第一次，在肿瘤进展过程中，将线粒体氧化还原代谢与细胞质氧化还原代谢解偶联。建筑 在此基础上，我们将检验SLC25A39介导的线粒体GSH输入的假说， 能够转移乳腺癌细胞的定植。为了解决这一问题，利用生物化学和遗传学 实验，我们将首先确定线粒体GSH使乳腺癌的确切机制， 转移到肺部然后我们将测试SLC25A39在肿瘤中线粒体GSH输入的作用。 形成和转移的研究。最后，SLC25A39蛋白水平 在肺定殖过程中显著增加，表明诱导线粒体的强选择性压力 转移时GSH摄取。因此，我们将确定线粒体GSH的可用性和肺 环境调节乳腺癌细胞中SLC25A39蛋白水平。该提案将揭示 线粒体GSH稳态在乳腺癌进展中的作用，并将确定一个区室化的传感 转移定植所必需的途径。

Project Summary Cancer cells require substantial antioxidant capacity to overcome toxic effects of reactive oxygen species (ROS). Despite their exclusive cytosolic production, cellular antioxidants are also abundantly present in organelles, particularly in mitochondria. In particular, mitochondria, as the source of reactive oxygen species (ROS), require substantial availability of antioxidants to protect its critical redox functions. While previous work suggests a link between mitochondrial redox metabolism and tumor growth, molecular mechanisms involved in maintaining mitochondrial redox homeostasis and the role of mitochondrial antioxidants in tumor progression are poorly understood. Among endogenous mitochondrial antioxidants, glutathione (GSH) is the dominant small molecule thiol, existing in millimolar concentrations. GSH is commonly upregulated in cancer cells, enabling metastatic colonization and resistance to chemotherapeutic drugs. In our previous work, using biochemical and proteomics methods, we identified SLC25A39, a mitochondrial membrane carrier of unknown function, to mediate GSH import into mitochondria of cancer cells. SLC25A39 loss strongly reduces mitochondrial GSH levels and its import, without impacting those in the cytosol. Our preliminary work suggests that SLC25A39 expression is associated with poor prognosis and decreased survival of breast cancer patients, and that SLC25A39 is necessary for breast cancer invasion and metastasis. This finding gave us the opportunity, for the first time, to uncouple mitochondrial redox metabolism from that of cytosol during tumor progression. Building upon this evidence, in this proposal, we will test the hypothesis that mitochondrial GSH import by SLC25A39 enables metastatic colonization of breast cancer cells. To address this, using biochemical and genetic experiments, we will first identify the precise mechanism by which mitochondrial GSH enables breast cancer cells to metastasize to lung. We will then test the role of mitochondrial GSH import by SLC25A39 in tumor formation and metastasis using mouse and human breast cancer models. Finally, SLC25A39 protein levels substantially increase during lung colonization, indicating a strong selective pressure to induce mitochondrial GSH uptake during metastasis. Therefore, we will determine how mitochondrial GSH availability and lung environment regulate SLC25A39 protein levels in breast cancer cells. This proposal will reveal the role of mitochondrial GSH homeostasis in breast cancer progression and will identify a compartmentalized sensing pathway essential for metastatic colonization.