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中存在严重缺陷，导致基因组不稳定，并使它们对PARP抑制剂（PARPi）和链间交联剂（ICLs）非常敏感。人们对使用这些药物治疗DNA修复途径中存在功能缺陷的更大范围的散发性癌症非常感兴趣。然而，即使是brca1突变的癌症也可以迅速对PARPi和icl产生耐药性，从而导致肿瘤进展。了解具有DNA修复缺陷的癌症中化学耐药发展的分子机制对于开发克服耐药和改善这些癌症患者预后的方法至关重要。我们最近在brca1突变细胞中发现了一种意想不到的耐药机制。DNA修复和检查点蛋白53BP1的缺失逆转了brca1突变细胞中存在的DNA修复缺陷，并诱导对PARPi和顺铂的耐药性。遗传性brca1相关乳腺癌和散发性“brca1样”乳腺癌的亚群均显示53BP1表达缺失。此外，53BP1的缺失与这些癌症的不良临床结果相关。我们假设53BP1功能异常会减轻brca1突变体和“brca1样”癌症中存在的同源介导的DNA修复缺陷，并导致化疗耐药。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的相互作用伙伴在调节brca1突变细胞中DNA修复缺陷中的作用；3)确定散发性癌症中获得性53BP1的缺失是否是对HDR潜在缺陷的补偿性突变。前两个目标将通过分析具有临床相关BRCA1零突变的小鼠乳腺癌细胞系的遗传定义集来实现。其中一些细胞系通过53BP1的体细胞突变获得了化学抗性。53BP1上游和下游的DNA因子在调节Brca1-/-细胞系DNA修复表型中的作用将通过使用特定的DNA修复试验仔细定义和验证。Aim 3将关注53BP1在更常见的散发性乳腺癌中调控DNA修复表型的作用，其中BRCA1基因完整但功能受损。本文将对鉴定出53BP1功能缺陷的人基底样细胞系进行系统分析，以确定53BP1功能障碍的分子机制，及其对DNA修复和耐药的影响。细胞系中的任何发现都将在临床注释的人类癌症标本中得到验证。通过这种方法，我们将获得53BP1功能如何影响DNA修复表型和遗传性brca1突变和散发性“brca1样”癌症对PARPi和ICL化疗药物的敏感性的新认识。这将最终导致新的方法来克服耐药性，并专门针对这些预后不良的癌症。

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