RI-alpha/RIAZ on Cell Growth in Breast Cancer

RI-α/RIAZ 对乳腺癌细胞生长的影响

• 批准号: 7107114
• 负责人: KHEW-VOON CHIN
• 金额: $ 21.79万
• 依托单位: UNIVERSITY OF TOLEDO HEALTH SCI CAMPUS
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-10 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7107114
• 关键词: RNA interference; apoptosis; athymic mouse; breast neoplasms; cAMP response element binding protein; cell growth regulation; cell transformation; cyclic AMP; enzyme activity; enzyme structure; growth inhibitors; microarray technology; neoplastic growth; protein kinase A; protein protein interaction; transcription factor; yeast two hybrid system

DESCRIPTION (provided by applicant): The effects of cAMP on cell growth and proliferation have been intensely investigated, but its mechanisms of action are not completely understood. The effects of cAMP are predominantly mediated by the cAMP-dependent protein kinase (PKA), which is composed of two distinct subunits, catalytic (C) and regulatory (R), forming a tetrameric holoenzymes, R2C2. The type I regulatory alpha (RIalpha) subunit expression is associated with hyperproliferation in human breast tissue and its overexpression in human breast cancer correlates with malignancy and poor prognosis. Increased expression of RI? stimulates growth, whereas overexpression of the C subunit does not produce such consequence. Most recently, RIalpha was shown to be a tumor suppressor gene in Carney Complex Syndrome. We have demonstrated previously novel interaction of RIalpha that is independent of the C subunit kinase activity. In this application, we show by yeast two-hybrid interaction cloning experiment that RIalpha associates with a novel BTB/POZ domain zinc finger transcription factor, termed RIalpha-associated zinc finger protein (RIAZ). We demonstrate that RIAZ is a cAMP-responsive transcriptional activator regulated by its interaction with RIalpha and potential cooperation with the cAMP-response element binding protein (CREB). We show further that RIAZ is aberrantly expressed in approximately 15% of human primary breast cancer. Furthermore, overexpression of RIAZ causes growth inhibition measured by [3H]thymidine uptake. The growth inhibition is enhanced by cAMP but not affected by the PKA inhibitor H-89. We hypothesize that RI? interaction with RIAZ may be a novel transcriptional mechanism in growth inhibition transduced by cAMP. In this proposal, we will: (1) determine the mechanisms of RI? interaction with RIAZ and regulation by cAMP; (2) investigate the mechanisms of RIAZ transcriptional response to cAMP; and (3) investigate the mechanisms of growth control by RI? interaction with RIAZ in response to cAMP. Our results will shed light on this novel interaction of RIalpha with RIAZ in growth inhibition.

描述（由申请人提供）：cAMP对细胞生长和增殖的影响已被深入研究，但其作用机制尚未完全了解。cAMP的作用主要由cAMP依赖性蛋白激酶（PKA）介导，PKA由两个不同的亚基组成，催化（C）和调节（R），形成四聚体全酶R2C2。I型调节α（RI α）亚基表达与人乳腺组织中的过度增殖相关，并且其在人乳腺癌中的过表达与恶性程度和不良预后相关。增加RI的表达？刺激生长，而C亚基的过表达不产生这种结果。最近，RIalpha被证明是Carney综合征的肿瘤抑制基因。我们已经证明了以前的新的相互作用的RIalpha是独立的C亚基激酶活性。在本申请中，我们通过酵母双杂交相互作用克隆实验表明，RIalpha与一种新的BTB/POZ结构域锌指转录因子相关联，称为RIalpha相关锌指蛋白（RIAZ）。我们证明，RIAZ是一个cAMP反应的转录激活因子调节其与RIalpha的相互作用和潜在的合作与cAMP反应元件结合蛋白（CREB）。我们进一步表明RIAZ在大约15%的人类原发性乳腺癌中异常表达。此外，RIAZ的过表达导致通过[3H]胸苷摄取测量的生长抑制。cAMP增强了生长抑制作用，但PKA抑制剂H-89不影响生长抑制作用。我们假设RI？与RIAZ的相互作用可能是cAMP介导的生长抑制的一种新的转录机制。在本研究中，我们将：（1）确定RI的机制？研究RIAZ与cAMP的相互作用及cAMP的调节作用;（2）研究RIAZ对cAMP的转录应答机制;（3）研究RI？与RIAZ的相互作用响应cAMP。我们的研究结果将揭示这种新的相互作用RIalpha与RIAZ的生长抑制。