Novel HDAC-interacting proteins that regulate breast cancer cell growth

描述(由申请人提供)：染色质结构在维持适当的基因表达方面起着关键作用。组蛋白的共价修饰形式的表观遗传变化，包括乙酰化，有助于调节染色质结构和基因表达。组蛋白脱乙酰酶(HDACs)是一组酶，它催化从组蛋白中去除乙酰基，这通常会导致基因抑制。由于控制细胞生长的基因表达的异常变化可导致癌症，HDAC已成为化疗药物的重要靶点。组蛋白去乙酰酶抑制剂目前正在进行临床试验，以治疗几种类型的癌症，包括乳腺癌。这些药物在优先阻止癌细胞生长方面比正常细胞有效。然而，目前使用的HDAC抑制剂针对HDAC的催化部位，并不区分人体内几种结构相似的HDAC。因此，这些HDAC抑制剂由于缺乏对单个HDAC的特异性而表现出不良的副作用。单独的HDAC存在于多亚单位蛋白质复合体中，一些已知的例子表明，这些与HDAC相关的蛋白质中的一些与特定的HDAC的催化活性相关并且是其催化活性所必需的。因此，作为抑制HDAC酶本身的替代方法，抑制HDAC相互作用的蛋白应该提供同样有效但更特异的治疗方法。这项建议将确定与HDAC1或HDAC3特定相关的蛋白质，这些蛋白质可以通过调节其特定的相关HDAC活性来控制乳腺癌的增殖。 具体目的：1.进行蛋白质组学分析，以确定人类细胞中与HDAC1和HDACs相关的蛋白质。生物化学鉴定HDAC及其差异相关蛋白所在的亚基组成和不同复合体的数量。2.确定哪些HDAC相互作用蛋白对HDAC活性是重要的，并确定HDAC1和HDAC相关蛋白如何影响其相关HDAC复合体的活性和完整性。3.使用siRNAs靶向浸润性乳腺癌细胞中含有HDAC1和3的复合体，并确定哪些蛋白质在被取消时会阻止癌细胞的生长。与公共卫生相关：目前许多抗癌药物在患者中显示出不想要的毒副作用，这是因为这些药物对其靶标的特异性很差。这项建议旨在为化疗药物寻找更具体的蛋白质靶点，以降低这些药物的毒性。

DESCRIPTION (provided by applicant): Chromatin structure plays a critical role in maintaining proper gene expression. Epigenetic changes in the form of covalent modifications on histones including acetylation help regulate chromatin structure and gene expression. One group of enzymes, the histone deacetylases (HDACs) catalyze the removal of acetyl groups from histones which generally leads to gene repression. Since cancer can be caused by aberrant changes in the expression of genes that control cell growth, HDACs have become important targets of chemotherapeutics. Histone deacetylase inhibitors are currently being tested in clinical trials to treat several types of cancers, including breast cancer. These drugs are effective at preferentially halting growth of cancer cells over normal cells. However, the HDAC inhibitors currently in use target the catalytic sites of HDACs and do not discriminate among the several structurally similar HDACs in humans. Thus these HDAC inhibitors exhibit undesirable side effects due to their lack of specificity for individual HDACs. Individual HDACs reside in multi-subunit protein complexes, and a few known examples show that some of these HDAC-associated proteins are associated with and required for the catalytic activity of a particular HDAC. Therefore, as an alternative to inhibiting the HDAC enzymes themselves, inhibiting HDAC- interacting proteins should provide just as effective, but more specific treatment. This proposal will identify and functionally characterize proteins specifically associated with either HDAC1 or HDAC3 that can control breast cancer proliferation through modulation of their specific associated HDAC's activity. Specific Aims: 1. Perform proteomics analysis to identify proteins associated with HDAC1 and HDACS in human cells. Biochemically identify the subunit composition and the number of distinct complex(es) the HDACs and their differentially associated proteins reside in. 2. Identify which HDAC-interacting proteins are important for HDAC activity and determine how HDAC1- and HDACS-associated proteins affect the activity and integrity of their associated HDAC complex. 3. Target HDAC1- and 3-containing complexes in invasive breast cancer cells using siRNAs and identify which proteins, when abrogated, halt cancer cell growth. Relevance to Public Health: Many current anti-cancer drugs show unwanted toxic side effects in patients due to poor specificity of these drugs for their targets. This proposal seeks to find more specific protein targets for chemotherapeutics which should decrease the toxicity of these drugs.