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

描述（由申请人提供）： 外源性双链断裂引起的DNA损伤反应已经得到了很好的研究，但是对导致链断裂的停滞复制叉的反应还不太清楚。同源重组（HR）已被主要研究作为DNA双链断裂修复的机制，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复制叉的同源依赖性修复。HR蛋白向阻断或切割的复制叉的募集依赖于HR的BRCA 1-BRCA 2途径，我们知道这在大量人类癌症中是有缺陷的。与两端双链断裂相比，这两种蛋白质在管理复制叉方面的作用可能不同。通过详细研究阻断DNA复制叉的后果，目标是开发治疗BRCA通路缺陷癌症的新的潜在策略。第一个目标将确定由于复制叉阻塞（RFB）而发生的事件以及RFB如何被切割从而导致复制叉崩溃。第二个目标将确定当HR存在缺陷时会发生什么，导致基因组不稳定。由于HR缺陷是一种肿瘤特异性表型，对复制相关事件的理解为新的治疗方法提供了机会。例如，我们需要了解致命的染色体畸变是如何由HR缺陷细胞中的复制相关断裂产生的。复制蛋白A、RAD 52和替代性末端连接的作用在决定细胞命运中都是潜在重要的。从这些拟议的实验中获得的知识应该可以为治疗这种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.