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中起着关键作用。包括乙酰化在内的组蛋白共价修饰形式的表观遗传变化有助于调节染色质结构和基因表达。一组酶，组蛋白去乙酰化酶（hdac）催化从组蛋白中去除乙酰基团，这通常导致基因抑制。由于癌症可由控制细胞生长的基因表达的异常变化引起，hdac已成为化疗药物的重要靶点。组蛋白去乙酰化酶抑制剂目前正在临床试验中用于治疗包括乳腺癌在内的几种癌症。这些药物在优先阻止癌细胞比正常细胞生长方面是有效的。然而，目前使用的HDAC抑制剂靶向HDAC的催化位点，并且不能区分人类几种结构相似的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。单个HDAC存在于多亚基蛋白复合物中，一些已知的例子表明，其中一些HDAC相关蛋白与特定HDAC的催化活性相关，并且是必需的。因此，作为抑制HDAC酶本身的一种替代方法，抑制HDAC相互作用蛋白应该提供同样有效，但更具体的治疗。本研究将鉴定和功能表征与HDAC1或HDAC3特异性相关的蛋白，这些蛋白可以通过调节其特异性相关的HDAC活性来控制乳腺癌的增殖。

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.