Kuster Anika, Mozaffari Nour L, Wilkinson Oliver J, Wojtaszek Jessica L, Zurfluh Christina, Przetocka Sara, Zyla Dawid, von Aesch Christine, Dillingham Mark S, Williams R Scott, Sartori Alessandro A
Institute of Molecular Cancer Research, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
School of Biochemistry, University of Bristol, University Walk, Clifton BS8 1TD, Bristol, UK.
Sci Adv. 2021 Feb 19;7(8). doi: 10.1126/sciadv.abc6381. Print 2021 Feb.
Cancer cells display high levels of DNA damage and replication stress, vulnerabilities that could be exploited by drugs targeting DNA repair proteins. Human CtIP promotes homology-mediated repair of DNA double-strand breaks (DSBs) and protects stalled replication forks from nucleolytic degradation, thus representing an attractive candidate for targeted cancer therapy. Here, we establish a peptide mimetic of the CtIP tetramerization motif that inhibits CtIP activity. The hydrocarbon-stapled peptide encompassing amino acid residues 18 to 28 of CtIP (SP) stably binds to CtIP tetramers in vitro and facilitates their aggregation into higher-order structures. Efficient intracellular uptake of SP abrogates CtIP localization to damaged chromatin, impairs DSB repair, and triggers extensive fork degradation. Moreover, prolonged SP treatment causes hypersensitivity to DNA-damaging agents and selectively reduces the viability of -mutated cancer cell lines. Together, our data provide a basis for the future development of CtIP-targeting compounds with the potential to treat patients with cancer.
癌细胞表现出高水平的DNA损伤和复制应激，这些弱点可被靶向DNA修复蛋白的药物利用。人类CtIP促进DNA双链断裂（DSB）的同源介导修复，并保护停滞的复制叉免受核酸酶降解，因此是靶向癌症治疗的一个有吸引力的候选对象。在这里，我们建立了一种抑制CtIP活性的CtIP四聚化基序的肽模拟物。包含CtIP第18至28位氨基酸残基的碳氢订书肽（SP）在体外与CtIP四聚体稳定结合，并促进它们聚集成更高阶结构。SP在细胞内的有效摄取消除了CtIP在受损染色质上的定位，损害了DSB修复，并引发广泛的叉状降解。此外，延长SP处理会导致对DNA损伤剂的超敏反应，并选择性降低突变癌细胞系的活力。总之，我们的数据为未来开发有潜力治疗癌症患者的靶向CtIP化合物提供了基础。
