ANDROGEN RECEPTOR DEGRADATION

雄激素受体降解

• 批准号: 6736888
• 负责人: AVROM J. CAPLAN
• 金额: $ 27.55万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6736888
• 关键词: androgen receptor; apoptosis; cell cycle; cell line; clinical research; enzyme mechanism; human tissue; immunocytochemistry; isozymes; molecular chaperones; molecular oncology; necrosis; phosphorylation; polymerase chain reaction; prostate neoplasms; protein degradation; protein folding; protein isoforms; protein protein interaction; protein signal sequence; protein structure function; receptor binding; site directed mutagenesis; transfection /expression vector; tumor suppressor proteins; ubiquitin

DESCRIPTION (Provided by applicant): The human androgen receptor (AR) is a member of the nuclear receptor superfamily and a major target of drugs used to control prostate cancer. This targeting is based on the AR being a determinant of prostate gland growth and differentiation. For this reason, it is important to understand how the AR is regulated inside cells. Previous studies showed that the AR is very unstable in its unliganded state, pointing to the importance of proteolysis to regulating AR steady state levels. Our studies are focused on the mechanisms underlying AR degradation, and how this process may itself be regulated. In preliminary studies, we show that the AR is degraded by the ubiquitin/proteasome pathway. This process is further shown to be affected by a protein called Chip that associates with molecular chaperones such as Hsp7O and Hsp9O. We also show that transfection of Chip inhibits growth of prostate cancer cells that also express AR. The long term goals of this project are to fully characterize the mechanisms governing AR degradation, and how Chip leads to prostate cancer cell growth inhibition In aim 1, we will determine the signals that target AR for degradation. Our hypothesis is that the signals for this event are based partly on AR conformation and partly on cis-acting sequences. We will first determine the role of protein folding in AR degradation, and then examine the role of a putative cis-acting signal, called a PEST sequence, in AR degradation. We will also test for the role of AR phosphorylation as a signal for its degradation. In aim 2, we will identify the sites of AR ubiquitinylation and the molecular components that catalyze this reaction. We will determine whether there is a functional relationship between ubiquitinylation, sumoylation, and the PEST sequence. We will also identify the E2 and E3 enzymes that conjugate ubiquitin to AR. Further studies will confirm that these enzymes are expressed in human prostate glandular epithelium. In aim 3, we will detrermine the mechanism by which Chip leads to arrest of prostate cancer cell growth. We will test whether there is a correlation between Chip effects on cell growth and decreasing AR levels, and we will compare the mechanisms of growth arrest in LNCaP cells and their androgen-independent derivative (LNCaPAI) in terms of apoptosis, cell cycle arrest or necrotic cell death.

描述（由申请人提供）：人类雄激素受体（AR）是核受体超家族的成员，也是用于控制前列腺癌的药物的主要靶标。这种靶向是基于 AR 是前列腺生长和分化的决定因素。因此，了解细胞内 AR 的调节机制非常重要。先前的研究表明，AR 在未配体状态下非常不稳定，这表明蛋白水解对于调节 AR 稳态水平的重要性。我们的研究重点是 AR 降解的机制，以及如何调节这一过程本身。在初步研究中，我们表明 AR 是通过泛素/蛋白酶体途径降解的。该过程进一步被证明受到一种名为 Chip 的蛋白质的影响，该蛋白质与 Hsp7O 和 Hsp9O 等分子伴侣相关。我们还表明，Chip 的转染可抑制也表达 AR 的前列腺癌细胞的生长。该项目的长期目标是充分表征控制 AR 降解的机制，以及 Chip 如何导致前列腺癌细胞生长抑制。在目标 1 中，我们将确定针对 AR 降解的信号。 我们的假设是，该事件的信号部分基于 AR 构象，部分基于顺式作用序列。我们将首先确定蛋白质折叠在 AR 降解中的作用，然后检查假定的顺式作用信号（称为 PEST 序列）在 AR 降解中的作用。我们还将测试 AR 磷酸化作为其降解信号的作用。在目标 2 中，我们将确定 AR 泛素化位点以及催化该反应的分子成分。我们将确定泛素化、苏酰化和 PEST 序列之间是否存在功能关系。我们还将鉴定将泛素与 AR 结合的 E2 和 E3 酶。进一步的研究将证实这些酶在人类前列腺腺上皮中表达。在目标 3 中，我们将确定 Chip 导致前列腺癌细胞生长停滞的机制。 我们将测试 Chip 对细胞生长的影响与降低 AR 水平之间是否存在相关性，并且我们将在细胞凋亡、细胞周期停滞或坏死性细胞死亡方面比较 LNCaP 细胞及其雄激素非依赖性衍生物 (LNCaPAI) 的生长停滞机制。