Molecular Mechanisms of Cellular Immortality

细胞永生的分子机制

• 批准号: 6405536
• 负责人: Sheila A Stewart
• 金额: $ 4.38万
• 依托单位: WHITEHEAD INSTITUTE FOR BIOMEDICAL RES
• 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
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6405536
• 关键词: Retroviridae; athymic mouse; complementary DNA; enzyme activity; neoplasm /cancer; neoplasm /cancer genetics; telomerase; telomere; viral carcinogenesis

Human tumor cells possess a number of characteristics that differ from their normal counterparts. Understanding the molecular details of these differences is critical to our understanding of the tumorigenic process and the rational development of novel cancer therapeutics. Acquisition of immortality is one attribute that is required in the development of a human tumor cell. Cellular immortality is the result of stable telomere maintenance in the face of ongoing cellular division. The telomere is a protective DNA-protein structure located at the end of all eukaryotic chromosomes. In normal cells continued rounds of replication result in telomere shortening that eventually leads to cell arrest. In contrast, tumor cells maintain stable telomere lengths through either the activation of the reverse transcriptase, telomerase, or through an alternative telomere maintenance mechanism (ALT). We have demonstrated that in telomerase-positive cell lines, which represent approximately 90% of all cancers, inhibition of telomerase activity results in loss of telomere maintenance and cell death. These studies also demonstrated that such inhibitors have no affect on telomerase- negative ALT cells. Currently the molecular details of the ALT pathway are unknown. Therefore, in this proposal we seek to unravel the molecular details of the ALT mechanism through the use of a non- biased retroviral screen. In addition, we have shown that in some cells ALT can not substitute for telomerase in tumorigensis raising the question of what role telomerase plays in tumorigenesis in addition to telomere length maintenance. One possibility is that in addition to telomere length telomerase may also aid in maintaining the correct telomere structure and that in some cases ALT may by insufficient. Therefore, we will examine the structure of the telomere in ALT cells in the presence or the absence of telomerase. The specific aims of this proposal are: 1. Identify the gene(s) responsible for telomerase-independent telomere maintenance. 2. Examine the role of ALT and telomerase in tumorigenesis. 2. Examine the role fo ALT and telomerase in tumorigenesis.

人类肿瘤细胞具有许多与正常对应物不同的特征。了解这些差异的分子细节对于我们对肿瘤过程的理解和新型癌症治疗剂的合理发展至关重要。不朽的获取是人类肿瘤细胞发展中所必需的一种属性。细胞永生是面对持续的细胞分裂的稳定端粒维持的结果。端粒是位于所有真核染色体末端的保护性DNA蛋白结构。在正常细胞中，继续复制会导致端粒缩短，最终导致细胞停滞。相反，肿瘤细胞通过逆转录酶，端粒酶或通过替代性端粒维持机制（ALT）的激活来保持稳定的端粒长度。我们已经证明，在端粒酶阳性细胞系中约为所有癌症的90％，抑制端粒酶活性会导致端粒维持和细胞死亡的丧失。这些研究还表明，这种抑制剂对端粒酶 - 负ALT细胞没有影响。目前，ALT途径的分子细节尚不清楚。因此，在此提案中，我们试图通过使用非偏置逆转录病毒筛查来揭示ALT机制的分子细节。此外，我们已经表明，在某些细胞中，ALT不能代替telomerigensis中的端粒酶，这提出了端粒酶在肿瘤发生中何种作用外，除端粒长度维持外。一种可能性是，除了端粒长度外，端粒酶还可能有助于维持正确的端粒结构，在某些情况下，Alt可能会通过不足。因此，我们将在存在或不存在端粒酶的情况下检查Alt细胞中端粒的结构。该提案的具体目的是：1。确定负责端粒酶无关的端粒维持的基因。 2。检查ALT和端粒酶在肿瘤发生中的作用。 2。检查fo Alt和端粒酶在肿瘤发生中的作用。