Molecular determinants of PARP inhibitor sensitivity in 11q-deleted malignancy

11q 缺失恶性肿瘤中 PARP 抑制剂敏感性的分子决定因素

• 批准号: 8881505
• 负责人: Sonia Franco
• 金额: $ 18.45万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2017-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8881505
• 关键词: 11q; 11q22; 11q23; Aftercare; Alleles; Antineoplastic Agents; B-Cell Lymphomas; B-Lymphocytes; BRCA1 gene; Biochemical; Biological Assay; Biological Markers; Cell Cycle Progression; Cell Line; Cell Survival; Cells; Chromosomal Stability; Clinical; Clinical Trials; DNA Damage; DNA Double Strand Break; DNA Repair; Data; Defect; Development; Dose; Double Strand Break Repair; Embryo; Fibroblasts; Future; Gene Dosage; Genes; Genetic; Genetic Epistasis; Genetic Recombination; Genome; Genomic Instability; Human; Ionizing radiation; Kinetics; Knowledge; Lesion; Malignant Neoplasms; Mediating; Modeling; Molecular; Molecular Cytogenetics; Mus; Mutation; Natural History; Neuroblastoma; Outcome; PARP inhibition; Pathway interactions; Phenotype; Phosphotransferases; Post-Translational Protein Processing; Pre-Clinical Model; Radiation Tolerance; Radiation induced double strand break; Relative (related person); Reporting; Role; Series; Signal Transduction; Testing; Work; ataxia telangiectasia mutated protein; base; cancer cell; cell transformation; chemotherapeutic agent; chemotherapy; genetic approach; homologous recombination; human H2AX protein; inhibitor/antagonist; insight; knock-down; neoplastic cell; neuroblastoma cell; novel; public health relevance; repaired; research clinical testing; research study; response; tumor

 DESCRIPTION (provided by applicant): Deletions at 11q are common in human malignancies and associate with poor clinical outcomes. In this context, deletions at 11q22, containing the Ataxia-Telangiectasia Mutated (ATM) locus, are frequently observed in B cell lymphomas (BCL) and, combined with mutation of the second allele, render these tumors ATM null. In contrast, deletions at 11q23, containing the histone H2AX locus, result in monoallelic H2AX expression in a subset of neuroblastomas (NB). Given the prominent roles for the ATM kinase and its substrate histone H2AX in the signaling and repair of DNA double-strand breaks (DSB), alterations in their copy number may result in differential responses to DNA damaging agents in cancer cells. In this context, PARP inhibitors (PARPi) are a novel class of DNA damaging chemotherapeutic agents that preferentially eliminate cells with defects in replication-associated DSBs. Based on these previous observations, we propose here to test the hypothesis that monoallelic expression of H2AX in 11q-deleted malignancies sensitizes them to PARPi, by conferring a defect in Homologous Recombination (HR)-mediated repair of PARPi-induced DSBs in human cancer cells. In support of our hypothesis, we provide strong genetic evidence that H2AX deficiency is synthetic lethal with PARP inhibition. First, we find that combined loss of H2AX and either of the two main PARPi targets, PARP1 or PARP2, results in embryonic lethality in the mouse. Secondly, we demonstrate a defect in the repair of replication-associated DSBs after treatment with PARPi, in an H2AX gene dose- dependent manner. Lastly, we demonstrate that H2AX is also limiting for DSB repair in NB cells with 11q23 deletion and monoallelic H2AX expression. To test our hypotheses, we will employ a combination of biochemical, molecular and cytogenetic assays on mouse primary and transformed cells and in human NB cells. Specifically, experiments in Aim 1 will employ murine cells to test the hypothesis that H2AX becomes limiting for HR-mediated repair of PARPi-induced lesions, characterize the underlying genetic pathway and define the relative contribution of PARP1 and PARP2 to these phenotypes. In Aim 2, we will assess PARPi sensitivity in 11q23-deleted NB cells as a function of H2AX gene dose and define roles for PARP1 and PARP2 in DSB repair in human cancer cells with reduced H2AX expression. In Aim 3, we will employ a novel murine model to examine nonoverlapping functions for ATM and H2AX in the repair of PARPi-induced lesions, modeling the subset of human cancers that co-delete the two factors. In the longer term, knowledge gained from these exploratory studies will increase our understanding of how PARPi interfere with the mechanisms that normally protect the genome during replication and facilitate the development of future clinical trials for biomarker development in a variety of human malignancies with 11q abnormalities.

 描述（适用提供）：在B细胞淋巴瘤（BCL）中经常观察到11q23的缺失，其中包含组蛋白H2AX基因座，并与第二等位基因的突变结合，使这些肿瘤ATM无效。相比之下，含有组蛋白H2AX基因座的11季度的缺失导致单位型H2AX表达在神经母细胞瘤（NB）的子集中。鉴于ATM激酶及其底物组蛋白H2AX在DNA双链断裂（DSB）中的重要作用（DSB），其拷贝数的变化可能会导致对癌细胞中DNA损伤剂的反应不同。在这种情况下，PARP抑制剂（PARPI）是一类新型的DNA损伤化学治疗剂，可更好地消除与复制相关的DSB中缺陷的细胞。基于这些先前的观察结果，我们在这里提出了以下假设：通过汇总同源性重组（HR）介导的PARPI诱导的人类癌细胞中Parpi诱导的DSB的缺陷，H2AX在11Q删除的恶性肿瘤中的单呈单相表达使它们感知到PARPI。为了支持我们的假设，我们提供了强有力的遗传证据，表明H2AX缺乏症是合成的致死性，并抑制了PARP。首先，我们发现综合的损失 H2AX以及两个主要PARPI靶标PARP1或PARP2中的任何一个都会导致小鼠的胚胎致死性。其次，我们以H2AX基因剂量依赖性方式证明了在用PARPI处理后修复复制相关的DSB的缺陷。最后，我们证明了H2AX也限制了具有11q23缺失和单一链球H2AX表达的NB细胞中DSB修复的限制。为了检验我们的假设，我们将在小鼠原代和转化的细胞以及人NB细胞中采用生化，分子和细胞遗传学评估的组合。具体而言，AIM 1中的实验将采用鼠类细胞来检验以下假设：H2AX限制了HR介导的PARPI诱导病变的修复，表征了基本的遗传途径，并定义了PARP1和PARP2对这些表型的相对贡献。在AIM 2中，我们将评估11q23删除的NB细胞中的PARPI敏感性，这是H2AX基因剂量的函数，并定义了H2AX表达降低的人类癌细胞中DSB修复中PARP1和PARP2的作用。在AIM 3中，我们将采用一种新型的鼠模型来检查ATM和H2AX的非重叠功能，以修复Parpi诱导的病变，对两个因素共降解的人类癌症的子集进行建模。从长远来看，从这些探索性研究中获得的知识将增加我们对PARPI干扰通常在复制过程中保护基因组的机制的理解，并支持未来的生物标志物发育临床试验的发展，从而在各种人类恶性肿瘤中具有11Q异常。