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）：认为转座酶活性在人类中已灭绝，因为DNA运动在较高的生物体中可能是有害的，从而导致基因组不稳定性和可能的​​恶性肿瘤。但是，我们分离了一种称为组蛋白甲基酶和非同源末端加入（NHEJ）DNA修复活性的人类转座酶蛋白。发现它与DNA连接酶IV相互作用，与其NHEJ修复活性一致。 Metnase也是超螺旋DNA的核酸酶优惠。因此，我们探讨了metnase在衰减复制的染色单体中的作用。 Metnase与临界衰减酶的拓扑异构酶II（TOPO II）相互作用，并在体外和细胞内增强了其在DNA衰减中的活性。需要完全增强TOPO II脱发活性，需要在metnase的转座酶结构域内的核酸酶活性。 MetNase提高了TOPO II脱发DNA的速率，并提高了TOPO II抵抗蛋白抑制剂ICRF-193的能力。 Metnase提高对ICRF-193的TOPO II耐药性的发现刺激了研究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。我们发现，Metnase可以防止依托泊苷在体外抑制TOPO II衰减，并介导对依托泊苷的细胞耐药性，从而在存在依托泊苷存在下促进增殖。 Metnase还促进了依托泊苷诱导的DSB的更快清除。因此，Metnase似乎介导对依托泊苷诱导的DNA损伤和细胞周期停滞的抗性。这是依托泊苷耐药性的一种新型机制，未经探索。该应用建议通过提出三个问题来定义metnase介导对依托泊苷的耐药性的机制：1）哪些上游信号调节了metnase降低依托泊苷DSB的能力？ 2）metnase降低依托泊苷DSB的下游途径是什么？ 3）Metnase水平是否在人类恶性肿瘤中对依托泊苷的预性临床抗性？