Assessing DNA polymerase theta as a therapeutic target in BRCA1 mutant cancer

项目摘要 DNA聚合酶θ（Polθ）活性的遗传破坏已被证明可有效靶向突变的BRCA 1。 细胞，而使BRCA 1野生型（WT）细胞保持完整。Polθ促进θ介导的DNA末端连接（TMEJ） 通过促进DNA突触的修复和在含有3'单链（ss）DNA的断裂位点的修复合成 悬垂部分。尽管目前正在开发Polθ活性的小分子抑制剂用于治疗 在BRCA 1突变型癌症中，关于激活TMEJ并导致Polθ-的机制知之甚少。 BRCA 1突变细胞的依赖性。此外，目前的范式假设同源重组， （HR）缺乏导致Polθi敏感性，因此PARPi反应性预期是Polθ的生物标志物 抑制剂（Polθi）敏感性。在我们的初步数据中，我们意外地发现了常用的Brca 1突变体， 在基因Polq（Polθ）敲除（KO）的情况下，细胞生长相对不受干扰，表明Polθi和PARPi 灵敏度可能不一定相关。在这个建议中，我们将阐明TMEJ的分子要求 激活和识别区分PARPi和Polθi敏感性的生物因子。我们将解决以下问题 具体目的：1）揭示Brca 1突变细胞中TMEJ激活的分子基础; 2）揭示遗传Polθ- 在Brca 1突变细胞中的依赖性;和3）检查Brca 1突变细胞中的药理学Polθ抑制。 总之，这些研究将为未来使用Polθi的临床研究提供信息。

PROJECT SUMMARY Genetic disruption of DNA polymerase theta (Polθ) activity has been shown to effectively target BRCA1 mutated cells, while leaving BRCA1 wild-type (WT) cells intact. Polθ facilitates theta-mediated DNA end joining (TMEJ) repair by promoting DNA synapsis and repair synthesis at break sites containing 3' single stranded (ss)DNA overhangs. Although small molecule inhibitors of Polθ activity are currently under development for the treatment of BRCA1 mutant cancers, very little is known regarding the mechanisms that activate TMEJ and result in Polθ- dependency in BRCA1 mutant cells. Moreover, the current paradigm assumes that homologous recombination (HR)-deficiency confers Polθi sensitivity, therefore PARPi responsiveness is expected to be a biomarker for Polθ inhibitor (Polθi) sensitivity. In our preliminary data, we unexpectedly identified commonly used Brca1 mutant cells that grow relatively unperturbed with genetic Polq (Polθ) knockout (KO), indicating that Polθi and PARPi sensitivity may not necessarily correlate. In this proposal, we will elucidate the molecular requirements for TMEJ activation and identify biological factors that distinguish PARPi and Polθi sensitivity. We will address the following Specific Aims: 1) reveal the molecular basis of TMEJ activation in Brca1 mutant cells; 2) uncover genetic Polθ- dependencies in Brca1 mutant cells; and 3) examine pharmacologic Polθ inhibition in Brca1 mutant cells. Collectively, these studies will be informative for future clinical studies employing Polθi.