Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Program in Virology, Graduate School of Arts and Sciences, Harvard University, Cambridge, MA, USA.
Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Center for DNA Damage and Repair, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
Cell Rep. 2021 Mar 2;34(9):108808. doi: 10.1016/j.celrep.2021.108808.
To identify genes whose loss confers resistance to CHK1 inhibitors, we perform genome-wide CRISPR-Cas9 screens in non-small-cell lung cancer (NSCLC) cell lines treated with the CHK1 inhibitor prexasertib (CHK1i). Five of the top six hits of the screens, MYBL2 (B-MYB), LIN54, FOXM1, cyclin A2 (CCNA2), and CDC25B, are cell-cycle-regulated genes that contribute to entry into mitosis. Knockout of MMB-FOXM1 complex components LIN54 and FOXM1 reduce CHK1i-induced DNA replication stress markers and premature mitosis during Late S phase. Activation of a feedback loop between the MMB-FOXM1 complex and CDK1 is required for CHK1i-induced premature mitosis in Late S phase and subsequent replication catastrophe, indicating that dysregulation of the S to M transition is necessary for CHK1 inhibitor sensitivity. These findings provide mechanistic insights into small molecule inhibitors currently studied in clinical trials and provide rationale for combination therapies.
为了鉴定那些导致细胞周期蛋白依赖性激酶 1（CHK1）抑制剂耐药的基因，我们在非小细胞肺癌（NSCLC）细胞系中进行了全基因组 CRISPR-Cas9 筛选，这些细胞系用 CHK1 抑制剂 prexasertib（CHK1i）处理。这些筛选的前六个命中靶点中的五个，MYBL2（B-MYB）、LIN54、FOXM1、细胞周期蛋白 A2（CCNA2）和 CDC25B，都是细胞周期调控基因，它们有助于进入有丝分裂。MMB-FOXM1 复合物成分 LIN54 和 FOXM1 的敲除减少了 CHK1i 诱导的 DNA 复制应激标记物和晚期 S 期过早有丝分裂。MMB-FOXM1 复合物和 CDK1 之间的反馈回路的激活是 CHK1i 诱导晚期 S 期过早有丝分裂和随后的复制灾难所必需的，这表明 S 到 M 期过渡的失调对于 CHK1 抑制剂的敏感性是必要的。这些发现为目前正在临床试验中研究的小分子抑制剂提供了机制上的见解，并为联合治疗提供了依据。
