The Response to a Site-Specific Blocked DNA Replication Fork in Human Cancers

描述(由申请人提供)： 外源性双链断裂对DNA损伤的反应已经被很好地研究了，但对停滞不前的复制叉子导致链切割的反应却不太清楚。同源重组(HR)被认为是DNA双链断裂修复的一种主要机制，但HR蛋白在保护基因组中的主要作用可能是由于切割的DNA复制叉的同源依赖修复。HR蛋白在被阻断或切割的复制叉处的募集取决于HR的BRCA1-BRCA2通路，我们知道该通路在相当数量的人类癌症中存在缺陷。与双链两端断裂相比，这两种蛋白质在管理复制分叉方面的作用可能不同。通过详细研究被阻断的DNA复制叉子的后果，目标是为BRCA途径缺陷的癌症的治疗开发新的潜在策略。第一个目标将确定作为复制分叉阻塞(RFB)的结果而发生的事件，以及如何切割RFB以导致复制分叉崩溃。第二个目标将决定当HR存在缺陷，导致基因组不稳定时会发生什么。由于HR缺乏是一种肿瘤特有的表型，对复制相关事件的了解为新的治疗方法提供了机会。例如，我们需要了解HR缺陷细胞中复制相关断裂是如何造成致命的染色体异常的。复制蛋白A、RAD52和可选择的末端连接在决定细胞命运方面都具有潜在的重要作用。从这些拟议的实验中获得的知识应该会为治疗这一途径存在缺陷的人类癌症提供新的见解。

DESCRIPTION (provided by applicant): The DNA damage response from exogenous double-strand breaks is well-studied, but the response to stalled replication forks that results in strand cleavage is less well understood. Homologous recombination (HR) has been predominantly studied as a mechanism of DNA double-strand break repair, but the major role of HR proteins in protecting the genome may be due to the homology-dependent repair of cleaved DNA replication forks. The recruitment of HR proteins to blocked or cleaved replication forks depends on BRCA1-BRCA2 pathway of HR, which we know is defective in a significant number of human cancers. The role of both proteins may not be the same in managing replication forks compared to double-strand breaks with two ends. By studying the consequences of a blocked DNA replication fork in detail, the goal is to develop new potential strategies for the therapy of BRCA-pathway deficient cancers. The first aim will determine events that occur as a result of replication fork block (RFB) and how the RFB is cleaved resulting in replication fork collapse. The second aim will determine what happens when there are defects in HR, resulting in genomic instability. Since HR-deficiency is a tumor-specific phenotype, the understanding of replication-associated events provides opportunities for novel therapeutics. For example, we need to understand how fatal chromosomal aberrations are created by replication-associated breaks in HR-deficient cells. The role of Replication Protein A, RAD52, and alternative end-joining are all potentially important in determining cell fate. The knowledge from these proposed experiments should allow new insight for treating human cancers with defects in this pathway.