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

 描述（由申请人提供）：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细胞和缺乏p53肿瘤抑制基因的细胞中选择性地复制叉塌陷成DSB。了解复制叉崩溃的过程有助于确定应用此类疗法的理想遗传背景。为了实现这一目标，我们最近已经证明，AURKA-PLK 1途径和SUMO靶向的E3泛素连接酶RNF 4是所需的叉崩溃和DSB形成时，ATR被抑制。在这项资助提案中，我们将1）剖析AURKA-PLK 1，RNF 4和ATR在复制叉稳定性方面的相互关系，2）表征由AURKA-PLK 1途径和RNF 4介导的驱动复制因子从叉脱离的泛素化事件，3）确定扩增是否 AURKA活性和复制体类小泛素化在人乳腺癌中的表达促进了小鼠培养细胞和原位移植肿瘤对ATR/CHK 1抑制剂的敏感性。这些研究将促进我们对ATR/CHK 1抑制后复制叉崩溃原因的理解，并研究扩增的AURKA-PLK 1活性和复制体类小泛素化在ATR/CHK 1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.