TRANSPOSASES IN ETOPOSIDE RESISTANCE

依托泊苷抗性中的转座酶

• 批准号: 8192937
• 负责人: Robert A Hromas
• 金额: $ 27.12万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-02 至 2013-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8192937
• 关键词: Antineoplastic Agents; Apoptosis; Cancer Patient; Cell Cycle Arrest; Cell Proliferation; Cell Survival; Cell division; Cells; Chromatids; Chromosomes; Cleaved cell; Clinical; Consensus; DNA; DNA Damage; DNA Double Strand Break; DNA Repair; DNA ligase IV; DNA repair protein; Drug Delivery Systems; Enzymes; Etoposide; Generations; Genomic Instability; Germ cell tumor; Health; Histones; Human; In Vitro; Investigation; Malignant Neoplasms; Malignant neoplasm of ovary; Malignant neoplasm of testis; Mediating; Mitosis; Movement; NBS1 gene; Neurofibrillary Tangles; Nonhomologous DNA End Joining; Organism; Outcome; Pathway interactions; Patients; Pharmaceutical Preparations; Phosphorylation; Proteins; Relative (related person); Resistance; Risk; Role; SET Domain; Sampling; Screening procedure; Signal Transduction; Site; Structure; Superhelical DNA; Tertiary Protein Structure; Testing; Topoisomerase II; Topoisomerase II inhibition; Topoisomerase-II Inhibitor; Transposase; base; cancer cell; cancer type; clinically relevant; endonuclease; experience; histone methyltransferase; improved; in vivo; inhibitor/antagonist; leukemia/lymphoma; lung small cell carcinoma; neoplastic; novel; nuclease; prevent; repaired; repository; response; small molecule; tumor; virtual

DESCRIPTION (provided by applicant): Transposase activity was thought to be extinct in humans because DNA movement can be deleterious in higher organisms, resulting in genomic instability and perhaps malignancy. However, we isolated a human transposase protein termed Metnase that had histone methylase and non-homologous end-joining (NHEJ) DNA repair activity. It was found to interact with DNA Ligase IV, consistent with its NHEJ repair activity. Metnase also was an endonuclease preferential for supercoiled DNA. We therefore explored Metnase's role in decatenating replicated chromatids. Metnase interacted with Topoisomerase II (Topo II ), the critical decatenating enzyme, and enhanced its activity in DNA decatenation, both in vitro and intracellularly. The nuclease activity within the transposase domain of Metnase was required for full enhancement of Topo II decatenating activity. Metnase improved the rate at which Topo II decatenated DNA, and increased the ability of Topo II to resist the decatenation inhibitor ICRF-193. The finding that Metnase improved Topo II resistance to ICRF-193 stimulated an investigation into whether it could mediate resistance to the clinically relevant Topo II inhibitor etoposide. We found that Metnase prevented inhibition of Topo II decatenation by etoposide in vitro, and mediated cellular resistance to etoposide, promoting proliferation in the presence of etoposide. Metnase also promoted a more rapid clearance of etoposide-induced DSB. Thus, Metnase appeared to mediate resistance to etoposide-induced DNA damage and cell cycle arrest. This is a novel mechanism of etoposide resistance that is unexplored. This application proposes to define the mechanism by which Metnase mediates resistance to etoposide by asking three questions: 1) What are the upstream signals that regulate the ability of Metnase to reduce etoposide DSBs? 2) What is the downstream pathway by which Metnase reduces etoposide DSBs? 3) Do Metnase levels predic clinical resistance to etoposide in human malignancy?

描述（由申请人提供）：转座酶活性被认为在人类中已经灭绝，因为 DNA 运动对高等生物体可能是有害的，导致基因组不稳定，甚至可能导致恶性肿瘤。然而，我们分离出了一种名为 Metnase 的人类转座酶蛋白，它具有组蛋白甲基化酶和非同源末端连接 (NHEJ) DNA 修复活性。人们发现它与 DNA 连接酶 IV 相互作用，与其 NHEJ 修复活性一致。 Metnase 也是一种优先用于超螺旋 DNA 的核酸内切酶。因此，我们探索了 Metnase 在连接复制染色单体中的作用。 Metnase 与关键的去连接酶拓扑异构酶 II (Topo II ) 相互作用，并增强其在体外和细胞内 DNA 去连接中的活性。 Metnase 转座酶结构域内的核酸酶活性是充分增强 Topo II 去连接活性所必需的。 Metnase 提高了 Topo II 脱链 DNA 的速率，并增强了 Topo II 抵抗脱链抑制剂 ICRF-193 的能力。 Metnase 改善了 Topo II 对 ICRF-193 的耐药性这一发现激发了人们对它是否可以介导对临床相关的 Topo II 抑制剂依托泊苷的耐药性的研究。我们发现 Metnase 可以在体外阻止依托泊苷对 Topo II 去连接的抑制，并介导细胞对依托泊苷的耐药性，从而在依托泊苷存在的情况下促进增殖。 Metnase 还促进依托泊苷诱导的 DSB 更快速的清除。因此，Metnase 似乎可以介导对依托泊苷诱导的 DNA 损伤和细胞周期停滞的抗性。这是一种尚未探索的依托泊苷耐药的新机制。本申请提出通过提出三个问题来定义 Metnase 介导依托泊苷耐药性的机制：1) 调节 Metnase 减少依托泊苷 DSB 能力的上游信号是什么？ 2) Metnase 还原依托泊苷 DSB 的下游途径是什么？ 3) Metnase 水平是否预示人类恶性肿瘤对依托泊苷的临床耐药性？