Effects of ATR-CHK1 inhibition on genome stability and cancer progression

 描述(申请人提供)：我们已经利用ATR检查点激酶的亚形态抑制来促进在癌基因表达的细胞和那些缺乏p53肿瘤抑制基因的细胞中选择性地向DSB折叠复制叉状突起。了解复制叉崩溃的过程有助于确定应用这种疗法的理想遗传背景。为此，我们最近证明，当ATR被抑制时，AURKA-PLK1途径和相扑靶向的E3泛素连接酶RNF4是叉子塌陷和DSB形成所必需的。在这项拨款提案中，我们将1)剖析AURKA-PLK1、RNF4和ATR在复制分叉稳定性中的调控相互关系，2)表征由AURKA-PLK1途径和RNF4介导的泛素化事件，这些事件驱动复制因子从分叉上解脱，以及3)确定扩增是否 在培养细胞和小鼠原位移植肿瘤中，人类乳腺癌中AURKA活性和复制体求和甲基化的研究提高了对ATR/CHK1抑制剂的敏感性。这些研究将促进我们对ATR/CHK1抑制后复制叉崩溃的原因的理解，并探讨放大的AURKA-PLK1活性和复制体求和化在ATR/CHK1抑制剂治疗反应中的预后价值。

 DESCRIPTION (provided by applicant): We have utilized hypomorphic suppression of the ATR checkpoint kinase to promote replication fork collapse into DSBs selectively in oncogene-expressing cells and those lacking the p53 tumor suppressor gene. Understanding the process of replication fork collapse is helpful in determining the ideal genetic contexts in which such therapies should be applied. Towards this objective, we have recently demonstrated that the AURKA-PLK1 pathway and the SUMO-targeted E3 ubiquitin ligase RNF4 are required for fork collapse and DSB formation when ATR is inhibited. In this grant proposal, we will 1) dissect the regulatory interrelationships between AURKA-PLK1, RNF4 and ATR in replication fork stability, 2) characterize the ubiquitination events mediated by the AURKA-PLK1 pathway and RNF4 that drive the disengagement of replication factors from the fork, and 3) determine if the amplification of AURKA activity and replisome sumoylation in human breast cancers promotes sensitivity to ATR/CHK1 inhibitors in cultured cells and orthotopically transplanted tumors in mice. These studies will advance our understanding of the causes of replication fork collapse upon ATR/CHK1 inhibition and investigate the prognostic value of amplified AURKA-PLK1 activity and replisome sumoylation in responsiveness to ATR/CHK1 inhibitor treatments.