The Role of pRb in Hypoxia-mediated Cell Cycle Arrest

描述（由申请人提供）：癌症是由获得增殖能力的细胞发展而来的，尽管有几种抑制生长的生化控制机制。细胞增殖导致形成由暴露于不同微环境的异质细胞群组成的肿瘤。随着肿瘤的生长，血管随机地渗入肿块，这导致肿瘤区域被剥夺营养和氧气。已经表明，具有低氧（低氧）区域优势的肿瘤对标准化疗和放疗不太敏感。这可能是由于在缺氧条件下，细胞停止分裂，因此对靶向活跃分裂细胞的传统疗法不太敏感。该项目旨在研究细胞对缺氧反应的生化机制，以便为开发针对这些细胞的治疗策略奠定基础。低氧介导的细胞增殖停滞的机制将通过分析维持在低氧条件下的非转化CV-1 P和卵巢癌细胞中的关键细胞分裂周期调节蛋白来检查。将研究肿瘤抑制蛋白视网膜母细胞瘤（pRb）以及其他口袋蛋白（p107和p130）在缺氧介导的细胞增殖停滞中的作用。在缺氧条件下，pRb通过pRb特异性激酶活性降低与pRb特异性磷酸酶活性增加的协同作用而被激活（去磷酸化）。这些酶在缺氧中被调节的机制将被检查。此外，pRb通过结合并抑制特定的细胞蛋白质来发挥其作为肿瘤抑制剂的活性。因此，将研究在低氧条件下维持的细胞中pRb的蛋白结合活性。最后，我们将研究p107和p130在缺氧介导的细胞增殖抑制中的作用。本提案中描述的研究的表现将作为未来研究的基础，旨在提高癌症治疗的疗效。

DESCRIPTION (provided by applicant): Cancer develops from cells that acquire the ability to proliferate despite several biochemical control mechanisms that suppress growth. Proliferation of cells leads to the formation of a tumor composed of heterogeneous groups of cells exposed to different microenvironments. As the tumor grows, blood vessels infiltrate the mass randomly which causes areas of the tumor to be deprived of nutrients and oxygen. It has been shown that tumors with a preponderance of hypoxic (low oxygen) regions are less sensitive to standard chemo- and radiotherapy. This may be due to the fact that under hypoxic conditions, cells stop dividing, and are thus less sensitive to traditional therapies that target actively dividing cells. This project is designed to investigate the biochemical mechanism of the cellular response to hypoxia in order to create the foundation for the development of treatment strategies that target these cells. The mechanism of hypoxia-mediated cell proliferation arrest will be examined by analysis of key cell division cycle regulatory proteins in nontransformed CV-1P and ovarian cancer cells maintained under hypoxic conditions. The role of the tumor suppressor protein, Retinoblastoma (pRb), as well as other pocket proteins, (p107 and p130) in hypoxia-mediated cell proliferation arrest will be investigated. Under hypoxic conditions, pRb becomes activated (dephosphorylated) by the concerted action of a decrease in pRb-specific kinase activity coupled with an increase in pRb-specific phosphatase activity. The mechanisms by which these enzymes are regulated in hypoxia will be examined. In addition, pRb exerts its activity as a tumor suppressor by binding to and inhibiting specific cellular proteins. Therefore, the protein binding activity of pRb in cells maintained under hypoxic conditions will be investigated. Finally, the function ofp 107 and p130 in hypoxia-mediated cell proliferation arrest will be examined. The performance of the studies described in this proposal will serve as a basis to build upon in future studies directed toward increasing the efficacy of cancer treatment.