NOVEL DNA DOUBLE STRAND BREAK REPAIR TARGETING THERAPEUTICS FOR CANCER TREATMENT

新型 DNA 双链断裂修复靶向治疗癌症

• 批准号: 8693254
• 负责人: LARRY A. SKLAR
• 金额: $ 46.26万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2017-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8693254
• 关键词: 2-cyclopentyl-5-(5-isoquinolylsulfonyl)-6-nitro-1H-benzo(D)imidazole; Affect; Aftercare; Biological Assay; Cell Cycle; Cell Death; Cell Line; Cell physiology; Cells; Chemicals; Collaborations; Complex; Critical Pathways; DNA Damage; DNA Double Strand Break; DNA Repair; DNA Repair Disorder; DNA Repair Pathway; DNA repair protein; Defect; Double Strand Break Repair; Exhibits; Flow Cytometry; Future; G1 Phase; Genomic Instability; Histones; Ionizing radiation; Lead; Libraries; Malignant Neoplasms; Mediating; Molecular; New Mexico; Nonhomologous DNA End Joining; Normal Cell; Normal tissue morphology; Pathway interactions; Pharmaceutical Chemistry; Pharmaceutical Preparations; Poly(ADP-ribose) Polymerases; Protein Deficiency; Proteins; Relapse; Reporter; Therapeutic; Therapeutic Agents; Tumor Suppressor Proteins; Universities; Validation; base; cancer cell; cancer stem cell; cancer therapy; cell type; dosage; genetic evolution; high throughput screening; homologous recombination; inhibitor/antagonist; malignant breast neoplasm; meetings; neoplastic cell; novel; novel therapeutics; public health relevance; repaired; response; screening; small molecule libraries; therapeutic target; tumor

DESCRIPTION: Cancer cells frequently inactivate DNA double strand break (DSB) repair proteins causing genomic instability and the genetic evolution of tumors. Inactivation of these proteins usually does not cause overt defects in DNA DSB repair due to the activity of compensatory repair pathways. We reason that identifying compounds that cripple these compensatory pathways will be the first step in developing therapeutic agents that can sensitize tumor cells, but not normal tissues to genotoxic cancer therapies. The DNA damage response histone protein H2AX is a dosage-dependent tumor suppressor that exhibits reduced expression in many cancers. H2AX deficiency leads to genomic instability, but not to overt defects in DNA DSB repair by non-homologous end joining (NHEJ). Deficiency in the NHEJ factor XLF also does not lead to demonstrable defects in NHEJ. However, the combined deficiency of H2AX and XLF leads to a severe block in DSB repair by NHEJ. These findings demonstrate that H2AX and XLF are in compensatory DSB repair pathways and that inhibition of one pathway in cells deficient in the other will lead to a profound block in NHEJ. In conjunction with the University of New Mexico Center for Molecular Discover (UNMCMD), we have developed a flow cytometric high throughput screen for chemical compounds that inhibit NHEJ. This screen has been optimized and used to screen a small library of compounds (1,500) achieving Z' scores of >0.6. Here, we propose to use this approach to screen a larger, more complex chemical library to identify compounds that inhibit NHEJ specifically in H2AX-deficient, but not wild type cells. We refer to these compounds as H2AX-specific Synthetic Inhibitors of NHEJ (SINs). A linear, multistep approach to validate the function of these compounds will also be developed. We believe that developing agents that selectively inhibit NHEJ in cancer cells will ultimately enable us to exploit DNA repair pathway defects to treat cancers. Moreover, this approach has significant advantages over current efforts to selectively inhibit the other major pathway of DSB repair, homologous recombination (HR) in cancer cells. Whereas HR only functions in DSB repair in dividing cells, NHEJ is required for DSB repair in all cells in the G0-G1 phases of the cell cycle. Thus, agents identified by our screen, which inhibit NHEJ will be effective in treating all cancer cells including the vast majority that are not actively dividing. Importantly, cancer stem cells, which are thought to be the basis for relapse of many cancers after treatment, exist primarily in G1 and would also be sensitized by SINs. In addition to identifying H2AX-specific SINs, completion of these studies will establish a linear pipeline for th future identification of SINs for treating cancers defective in a broad range of DNA DSB repair proteins. Moreover, they will also identify novel DSB repair pathways used by normal cells and cancer cells.

描述：癌细胞经常失活DNA双链断裂（DSB）修复蛋白，导致基因组不稳定性和肿瘤的遗传进化。由于补偿性修复途径的活性，这些蛋白质的灭活通常不会导致DNA DSB修复的明显缺陷。我们认为，鉴定削弱这些补偿途径的化合物将是开发可以使肿瘤细胞敏感的治疗剂的第一步，但不是正常的组织对遗传毒性癌症疗法。 DNA损伤反应组蛋白H2AX是剂量依赖性肿瘤抑制因子，在许多癌症中表现出降低的表达。 H2AX缺乏会导致基因组不稳定性，但不会通过非同源末端连接（NHEJ）在DNA DSB修复中明显缺陷。 NHEJ因子XLF的缺陷也不会导致NHEJ中的可证明缺陷。但是，H2AX和XLF的综合缺乏导致NHEJ在DSB修复中的严重阻滞。这些发现表明，H2AX和XLF处于补偿性DSB修复途径中，并且抑制另一个细胞中一种途径的抑制作用将导致NHEJ的深刻障碍。与新墨西哥大学分子发现中心（UMCMD）一起，我们开发了抑制NHEJ的化合物的流式细胞术高通量筛选。此屏幕已被优化，并用于筛选一个小型化合物（1,500）的小库，其Z'得分> 0.6。在这里，我们建议使用这种方法来筛选一个更大，更复杂的化学文库，以识别抑制NHEJ在H2AX缺陷型但不是野生型细胞中的化合物。我们将这些化合物称为NHEJ（SINS）的H2AX特异性合成抑制剂。也将开发一种线性的多步验证方法来验证这些化合物的功能。我们认为，在癌细胞中有选择地抑制NHEJ的开发剂最终将使我们能够利用DNA修复途径缺陷来治疗癌症。此外，这种方法比当前的努力具有显着优势，以选择性地抑制DSB修复，癌细胞同源重组（HR）的其他主要途径。 HR仅在分裂细胞中的DSB修复中起作用，而在细胞周期的G0-G1阶段，所有细胞中DSB修复需要NHEJ。因此，我们屏幕识别的试剂抑制NHEJ将有效治疗所有癌细胞，包括绝大多数不积极分裂的癌细胞。重要的是，被认为是治疗后许多癌症复发的基础的癌症干细胞主要存在于G1中，并且也会受到罪恶的敏感。除了确定H2AX特异性的罪恶之外，这些研究的完成还将建立线性管道，用于将来鉴定出在广泛的DNA DSB修复蛋白中有缺陷的癌症识别的罪行。此外，他们还将确定正常细胞和癌细胞使用的新型DSB修复途径。