Signal Transduction Events and the Regulation of Cell Growth

信号转导事件和细胞生长的调节

• 批准号: 6433123
• 负责人: JANE B TREPEL
• 金额: --
• 依托单位: DIVISION OF CLINICAL SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6433123
• 关键词: HMG coA reductases; N acetylglucosamine; antineoplastics; biological signal transduction; breast neoplasms; cell cell interaction; cell growth regulation; cellular oncology; confocal scanning microscopy; cytoskeleton; enzyme inhibitors; genetic regulation; glycosylation; immunoprecipitation; lovastatin; neoplastic cell; nervous system neoplasms; phosphorylation; posttranslational modifications; prostate neoplasms; retinoblastoma protein; transcription factor; tumor suppressor genes

This project is designed to increase our understanding of cancer cell biology and to develop a new approach to cancer treatment through the study of growth-regulatory signal transduction events. This work is currently focused on (1) novel aspects of the regulation of cancer cell growth by the retinoblastoma susceptibility gene family and (2) the molecular mechanism of negative growth regulation by cyclic AMP. The retinoblastoma protein is currently thought to function only in the cell nucleus and only in the G1 phase of the cell cycle. In contrast, using confocal microscopy and co-immunoprecipitation techniques we found that Rb is associated with the cell cytoskeleton and that this localization is regulated as a function of the cell cycle. These data were supported by in vitro transcription-translation experiments using wild type and mutant GST-Rb constructs, and by transient transfections using hemagglutinin-tagged wild type and mutant Rb constructs. These data suggest a new model of tumor suppressor gene function, in which the tumor suppressor gene product is responsive to cell-cell or cell-substratum interactions. While studying the anticancer action of cyclic AMP we determined that elevation of intracellular cyclic AMP causes loss of cyclin A expression and down-regulation of cyclin A-regulated cyclin-dependent kinase activity. Our recent studies on the mechanism of cyclic AMP-induced G1 arrest in prostate cancer cells demonstrate that cyclic AMP induces transcription of the cyclin-dependent kinase inhibitor p21. We are mapping the cyclic AMP-responsive element on the p21 promoter and have begun characterizing the factors activating the proximal promoter in response to cyclic AMP. These studies demonstrate that cAMP activates the p21 promoter through a novel, non-CRE-mediated mechanism. Furthermore, the data demonstrate the role of histone acetylases (HATs) in p21 promoter activation in response to cAMP.

本项目旨在增加我们对癌细胞生物学的理解，并通过研究生长调节信号转导事件来开发癌症治疗的新方法。这项工作目前集中在(1)视网膜母细胞瘤易感基因家族调控癌细胞生长的新方面和(2)环状AMP负生长调控的分子机制。视网膜母细胞瘤蛋白目前被认为仅在细胞核中起作用，仅在细胞周期的G1期起作用。相比之下，使用共聚焦显微镜和共免疫沉淀技术，我们发现Rb与细胞骨架相关，并且这种定位受细胞周期的功能调节。这些数据得到了野生型和突变型GST-Rb构建体的体外转录翻译实验以及血凝素标记的野生型和突变型Rb构建体的瞬时转染的支持。这些数据提示了一种新的肿瘤抑制基因功能模型，其中肿瘤抑制基因产物对细胞-细胞或细胞-基质相互作用有反应。在研究环AMP的抗癌作用时，我们发现细胞内环AMP的升高会导致细胞周期蛋白A表达的缺失和细胞周期蛋白A调节的周期蛋白依赖性激酶活性的下调。我们最近对环磷酸腺苷诱导前列腺癌细胞G1阻滞机制的研究表明，环磷酸腺苷诱导周期蛋白依赖性激酶抑制剂p21的转录。我们正在绘制p21启动子上的环AMP响应元件，并开始表征响应环AMP激活近端启动子的因子。这些研究表明，cAMP通过一种新的、非cre介导的机制激活p21启动子。此外，这些数据证明了组蛋白乙酰化酶（HATs）在响应cAMP的p21启动子激活中的作用。