53BP1-Mediated Regulation of DNA Repair and Chemoresistance

53BP1-介导的 DNA 修复和化疗耐药性调节

• 批准号: 9091478
• 负责人: Shridar Ganesan
• 金额: $ 32.93万
• 依托单位: RBHS -CANCER INSTITUTE OF NEW JERSEY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9091478
• 关键词: BRCA1 gene; Biological Assay; Breast Cancer cell line; Cancer Prognosis; Cell Line; Cells; Cisplatin; Clinical; Crosslinker; DNA; DNA Repair; DNA Repair Pathway; Data; Defect; Development; Elements; Functional disorder; Genomic Instability; Human; Inherited; Lead; Malignant Neoplasms; Mediating; Methods; Modeling; Molecular; Mus; Mutation; Nonhomologous DNA End Joining; Outcome; Pathway interactions; Patients; Phenotype; Phosphorylation; Platinum; Play; Proteins; Regulation; Resistance; Resistance development; Role; Somatic Mutation; Specimen; Structure; cancer cell; chemotherapeutic agent; clinically relevant; homologous recombination; improved; improved outcome; inhibitor/antagonist; insight; interest; malignant breast neoplasm; mutant; novel strategies; null mutation; outcome forecast; p53-binding protein 1; repaired; resistance mechanism; restoration; triple-negative invasive breast carcinoma; tumor progression

DESCRIPTION (provided by applicant): Cancer cells lacking functional BRCA1 have a profound defect in HDR that leads to genomic instability and renders them exquisitely sensitive to PARP inhibitors (PARPi) and interstrand crosslinkers (ICLs). There is great interest in using these agents to treat a larger spectrum of sporadic cancers with functional defects in DNA repair pathways. However, even BRCA1-mutant cancers can rapidly develop resistance to PARPi and ICLs leading to tumor progression. Understanding the molecular mechanism underlying the development of chemoresistance in cancers with defined defects in DNA repair will be critical for developing methods to overcome resistance and improve the outcome of patients with these cancers. We have recently identified an unexpected mechanism of chemo-resistance in BRCA1-mutant cells. Loss of the DNA- repair and checkpoint protein 53BP1 reverses the DNA repair defect present in BRCA1-mutant cells and induces resistance to both PARPi and cisplatin. Subsets of both hereditary BRCA1-associated breast cancers and sporadic "BRCA1-like" breast cancers show loss of 53BP1 expression. Moreover, loss of 53BP1 is associated with poor clinical outcome in these cancers. We hypothesize that abnormalities in 53BP1 function will alleviate the defect in homology-mediated DNA repair present in BRCA1-mutant and "BRCA1-like" cancers, and lead to chemo-resistance. To investigate this hypothesis we will: 1) Determine the functional elements of 53BP1 required to maintain the HDR defect present in BRCA1-mutant cells. 2) Determine the role of interacting partners of 53BP1 in regulating the DNA repair defect in BRCA1-mutant cells and 3) Determine whether or not acquired loss of 53BP1 in sporadic cancers is a compensating mutation for an underlying defect in HDR. The first two aims will be achieved through the analysis of genetically defined sets of murine breast cancer cell lines with clinically relevant null mutations in BRCA1. Several of these cell lines hav acquired chemo-resistance through somatic mutations in 53BP1. The role of DNA factors upstream and downstream of 53BP1 in regulating the DNA repair phenotype in Brca1-/- cell lines will be carefully defined and validated through use of specific DNA repair assays. Aim 3 will focus on the role of 53BP1 in regulating the DNA repair phenotype in the more common sporadic breast cancers in which BRCA1 is genetically intact but functionally impaired. Here human basal-like cell lines identified to have defects in 53BP1 function will be systematically analyzed to determine the molecular mechanism of 53BP1 dysfunction, and its effect on DNA repair and chemo-resistance. Any findings in cell lines will be validated in clinically annotated sets of human cancer specimens. By this approach we will gain a new understanding of how 53BP1 function impacts the DNA repair phenotype and sensitivity of both hereditary BRCA1-mutant and sporadic "BRCA1-like" cancers to PARPi and ICL chemotherapeutic agents. This will ultimately lead to new approaches to overcome resistance and specifically target these poor-prognosis cancers.

描述（由申请人提供）：缺乏功能性BRCA1的癌细胞在HDR中具有深远的缺陷，从而导致基因组不稳定性，并使它们对PARP抑制剂（PARPI）和链间交叉链接链（ICL）非常敏感。人们非常有兴趣使用这些药物治疗DNA修复途径中具有功能缺陷的零星癌症范围。但是，即使是BRCA1突变癌也可以快速发展对PARPI和ICL的抗性，从而导致肿瘤进展。了解在DNA修复中定义缺陷的癌症中化学耐药性发展的分子机制对于开发克服耐药性和改善这些癌症患者的结果的方法至关重要。我们最近确定了BRCA1突变细胞中化学抗性的意外机制。 DNA修复和检查点蛋白53BP1的丧失会逆转BRCA1突变细胞中存在的DNA修复缺陷，并诱导对PARPI和顺铂的抗性。遗传性BRCA1相关的乳腺癌和零星的“ BRCA1样”乳腺癌的子集均显示出53BP1表达的损失。此外，在这些癌症中，损失53BP1与临床结果不佳有关。我们假设53BP1功能的异常会减轻BRCA1突变和“ BRCA1样癌症”中同源介导的DNA修复的缺陷，并导致化学耐药性。为了研究这一假设，我们将：1）确定维持BRCA1突变细胞中存在的HDR缺陷所需的53BP1的功能元件。 2）确定53BP1相互作用伴侣在调节BRCA1突变细胞中DNA修复缺陷中的作用； 3）确定在散发性癌症中获得的53BP1损失是否是HDR中潜在缺陷的补偿突变。通过分析BRCA1中具有临床相关的无效的null突变，将通过分析遗传定义的鼠类乳腺癌细胞系来实现前两个目标。这些细胞系中有几种通过53BP1中的体细胞突变获得了化学抗性。 53BP1上游和下游DNA因子在调节BRCA1 - / - 细胞系中DNA修复表型中的作用将通过使用特定的DNA修复分析来仔细定义和验证。 AIM 3将集中于53BP1在调节DNA修复表型中的作用，在BRCA1在遗传上完好无损但功能障碍的更常见的零星乳腺癌中。在这里，将系统地分析被确定在53BP1功能中具有缺陷的人基基细胞系，以确定53BP1功能障碍的分子机制及其对DNA修复和化学耐药性的影响。细胞系中的任何发现将在临床注释的人类癌标本集中验证。通过这种方法，我们将对53BP1功能如何影响遗传性BRCA1突变剂和零星的“ BRCA1样”癌对PARPI和ICL化学治疗剂的DNA修复表型和灵敏度有了新的了解。这最终将导致克服抗药性的新方法，并特别针对这些不良的预测癌。

项目成果

The DNA repair function of CUX1 contributes to radioresistance.

• DOI: 10.18632/oncotarget.14875
• 发表时间: 2017-03-21
• 期刊: Oncotarget
• 作者: Ramdzan ZM;Ginjala V;Pinder JB;Chung D;Donovan CM;Kaur S;Leduy L;Dellaire G;Ganesan S;Nepveu A
• 通讯作者: Nepveu A