Targeting Metabolic Liabilities in Cancer

摘要/摘要 在转化的细胞中，积累生物质的需求需要大量的代谢途径改变。 了解这种改变的新陈代谢将使识别负债，可用于癌症 疗法在先前的工作中，我们发现高氧应激是一个相当大的推动代谢途径的力量 乳腺癌的依赖性。事实上，在高氧和低氧条件下， NFS 1是乳腺癌转移到肺部所必需的。此外，NFS 1位于一个放大的 肺腺癌中的阳性选择区域。因此，从先前的工作中，我们得出结论， 肺的氧环境是一个关键的代谢因素， 部分通过NFS 1来适应。我们的工作是第一次描述这个关键途径在癌症中的作用。 该补助金的目的是获得NFS 1要求的机械理解，重点是基础- 比如乳腺癌（BLBC）。NFS 1是铁硫簇（ISC）生物合成中的关键酶， 人类48种蛋白质中的辅因子。我们发现BLBC细胞系比鲁米那细胞系更敏感， 抑制NFS 1。我们建议确定这一观察的机制基础， 将我们的发现扩展到其他癌症亚型。我们将抑制一组乳腺癌中含有ISC的蛋白质， 癌细胞系，并验证BLBC中的差异需要。经验证的靶标将被抑制， 基于异种移植物的乳腺癌和转移模型，以评估它们对这些过程的影响。 许多含有ISC的基因参与基因组完整性的维持。我们的前期工作 NFS 1抑制导致双链DNA断裂的形成。这些观察导致 我们抑制POLE，一种关键的基因组完整性酶。有趣的是，抑制POLE也阻止了 在BLBC细胞系中增殖和诱导双链断裂的作用远远超过管腔细胞系。以前的工作有 表明BLBC在DNA修复方面存在缺陷，这可能使其对治疗敏感。因此我们将 抑制POLE并评估对DNA复制、起点激发、复制叉停滞和重新启动的影响， 和修复损坏的复制叉。这些实验将有助于我们的基本 了解BLBC对DNA复制抑制和DNA损伤诱导的敏感性。 最后，NFS 1抑制通过非凋亡形式的细胞死亡使细胞对氧化损伤敏感 称为铁性下垂。我们的发现引出了一个有趣的可能性，即铁饥饿反应的激活 在铁充足的条件下，从而诱使癌细胞摄取过量的铁， 易受进一步的氧化应激和死亡的铁凋亡。通过机械地理解如何最好地 激活NFS 1下游的铁饥饿反应，我们预计我们将获得以下益处 诱导对氧化剂的敏感性增加，而不必靶向通常的细胞必需途径。

Summary/Abstract In transformed cells the demand to accumulate biomass requires substantial metabolic pathway alteration. Understanding this altered metabolism will enable identification of liabilities that can be exploited for cancer therapy. In prior work, we found that hyperoxic stress is a considerable force driving metabolic pathway dependence in breast cancer. Indeed, the enzyme most differentially required in high versus low oxygen environments, NFS1, is required for breast cancer metastasis to the lung. Moreover, NFS1 lies in an amplified region under positive selection in lung adenocarcinoma. Therefore, from prior work we conclude that the high oxygen environment of the lung is a key metabolic factor to which incipient breast metastases and lung tumors uniquely adapt, in part, via NFS1. Ours is the first work to describe a role for this critical pathway in cancer. The purpose of this grant is to gain mechanistic understanding of the NFS1 requirement, focusing on basal- like breast cancer (BLBC). NFS1 is a key enzyme in the biosynthesis of iron-sulfur clusters (ISC), essential cofactors in 48 proteins in humans. We found that BLBC cell lines are strikingly more sensitive than luminal lines to suppression of NFS1. We propose to identify the mechanistic underpinnings of this observation, and extend our findings to other cancer subtypes. We will suppress ISC containing proteins in a panel of breast cancer cell lines and verify which are differentially required in BLBC. Validated targets will be inhibited in xenograft-based models of breast cancer and metastasis to assess their impact on these processes. Many ISC containing genes are involved in the maintenance of genomic integrity. Our preliminary work reveals that NFS1 suppression results in the formation of double strand DNA breaks. These observations led us to suppress POLE, a key genomic integrity enzyme. Interestingly, suppression of POLE also blocks proliferation and induces double strand breaks in BLBC cell lines far more than luminal lines. Prior work has indicated that BLBC has defects in aspects of DNA repair that may sensitize them to therapy. Therefore we will suppress POLE and assess the impact on DNA replication, origin firing, replication fork stalling and restarting, and the repair of damaged replication forks. These experiments will contribute to our fundamental understanding of the sensitivity of BLBC to inhibition of DNA replication and induction of DNA damage. Finally, NFS1 suppression sensitizes cells to oxidative damage via a non-apoptotic form of cell death termed ferroptosis. Our findings lead to the intriguing possibility that activation of the iron-starvation response in iron-replete conditions, thereby tricking cancer cells into taking up excess iron, will render them highly susceptible to further oxidative stress and death by ferroptosis. By mechanistically understanding how best to activate the iron-starvation response downstream of NFS1, we anticipate that we will gain the benefit of inducing increased sensitivity to oxidants without having to target a generally cell-essential pathway.