Molecular mechanisms of chemoresistance in breast cancer

摘要： 细胞凋亡是程序性细胞死亡的一种形式，其在正常组织稳态中起关键作用， 发展响应于各种遗传毒性或细胞毒性应激物，细胞凋亡通过释放 细胞色素c从线粒体，这促进成核的结构被称为线粒体， 激活半胱氨酸蛋白酶半胱天冬酶。与未转化的细胞相比，癌细胞表现出显著的 通过阻断线粒体细胞色素c释放和/或通过抑制线粒体DNA酶体来抵抗细胞凋亡 在细胞色素C释放后形成。 已知受体酪氨酸激酶ErbB 2的过度表达与患者的不良预后相关。 乳腺癌患者。尽管ErbB 2特异性分子抑制剂的可用性，但大多数ErbB 2- 过表达的乳腺癌最终在一段时间内发展出对这些抑制剂的抗性（即， 获得性抗性），表明存在目前未表征的化学抗性机制。 在这个建议中，我调查的分子机制，有助于乳腺癌细胞凋亡抑制 对拉帕替尼（一种FDA批准的ErbB 2抑制剂）具有获得性耐药性。我的核心假设是 抑制溶酶体形成在乳腺癌中获得性拉帕替尼耐药性中起关键作用。这 这一假设是根据我们实验室和其他实验室的证据提出的， 溶酶体抑制可以通过两个关键的独立途径发生：HSP 90低磷酸化和CAS 下调通过这些机制的凋亡体抑制可以覆盖由细胞凋亡引起的细胞死亡信号。 各种促凋亡刺激。为此，我将追求以下两个具体目标：1）确定 HSP 90低磷酸化在获得性拉帕替尼耐药中的作用，2）阐明HSP 90低磷酸化在获得性拉帕替尼耐药中的分子作用。 CAS下调机制。我的主要职业目标是在一个学术机构获得一个终身职位。 在美国一所主要大学里。我的长期目标是建立一个独立的研究生涯作为一个分子 癌症生物学家为了实现这些目标，我希望既发展我的知识基础， 在整个拟议的研究期间增加我的技术技能。这次培训应该是 在杜克大学医学中心的Kornbluth实验室很容易获得;我们的实验室有相当多的 在复杂信号通路的生化分析和分子解剖方面的专业知识， 细胞凋亡和细胞周期进程。此外，我还获得了两位杰出的合作者， Spector和Mark Dewhirst是乳腺癌和小鼠肿瘤领域的研究人员， 异种移植物癌症模型。此外，为了促进和确保我在 职业发展奖期间，我组织了一个咨询委员会， 在与我的研究和职业目标相关的不同领域拥有专业知识的高级科学家。统称 拟议的研究将提供重要的洞察机制的化学抗性和潜在的战略 用于使细胞对促凋亡剂敏感。此外，这项工作将为我提供建立 我是独立调查员

Abstract: Apoptosis is a form of programmed cell death that plays a crucial role in normal tissue homeostasis and development. In response to various genotoxic or cytotoxic stressors, apoptosis occurs by release of cytochrome c from the mitochondria, which promotes nucleation of a structure known as the apoptosome to activate cysteine proteases called caspases. In contrast to untransformed cells, cancer cells exhibit marked resistance to apoptosis by blocking mitochondrial cytochrome c release and/or by inhibiting apoptosome formation following cytochrome c release. Overexpression of the receptor tyrosine kinase ErbB2 is known to be associated with poor prognosis in breast cancer patients. Despite the availability of ErbB2-specific molecular inhibitors, the majority of ErbB2- overexpressing breast cancers eventually develop resistance to these inhibitors over a period of time (i.e., acquired resistance), suggesting the presence of currently uncharacterized mechanisms of chemoresistance. In this proposal, I investigate the molecular mechanisms contributing to apoptotic inhibition in breast cancers with acquired resistance to lapatinib, an FDA-approved ErbB2 inhibitor. It is my central hypothesis that inhibition of apoptosome formation plays a critical role in acquired lapatinib resistance in breast cancer. This hypothesis was formulated based on evidence from our laboratory as well as from others demonstrating that apoptosome inhibition can occur by two key independent pathways: HSP90¿ hypophosphorylation and CAS downregulation. Apoptosome inhibition by these mechanisms may override cell death signals caused by various pro-apoptotic stimuli. Towards this end, I will pursue the following two specific aims: 1) to determine the role of HSP90¿ hypophosphorylation in acquired lapatinib resistance, and 2) to elucidate the molecular mechanism of CAS downregulation. My primary career goal is to obtain a tenure-track position in an academic setting at a major U.S. university. My long-term goal is to build an independent research career as a molecular cancer biologist. To achieve these goals, I hope to both develop my intellectual knowledge base as well as increase my technical skill repertoire throughout the duration of the proposed study. This training should be readily attainable in the Kornbluth laboratory at Duke University Medical Center; our lab has considerable expertise in the biochemical analysis and molecular dissection of complex signaling pathways, both during apoptosis and cell cycle progression. In addition, I have obtained two outstanding collaborators, Drs. Neil Spector and Mark Dewhirst, who are established investigators in the fields of breast cancer and mouse xenograft models of cancer, respectively. Moreover, in order to promote and assure my progress during the Career Development Award period, I have organized an advisory committee consisting of well-established senior scientists with expertise in different areas relevant to my research and career goals. Collectively, the proposed studies will provide significant insight into mechanisms of chemoresistance and potential strategies for sensitizing cells to pro-apoptotic agents. Moreover, this work will provide me with the means to establish myself as an independent investigator.