The CRUK Gene Function Laboratory, The Institute of Cancer Research, London, UK.
Breast Cancer Now Toby Robins Breast Cancer Research Centre, The Institute of Cancer Research, London, UK.
Mol Oncol. 2024 Feb;18(2):369-385. doi: 10.1002/1878-0261.13537. Epub 2023 Oct 22.
The F-box and WD repeat domain containing 7 (FBXW7) tumour suppressor gene encodes a substrate-recognition subunit of Skp, cullin, F-box (SCF)-containing complexes. The tumour-suppressive role of FBXW7 is ascribed to its ability to drive ubiquitination and degradation of oncoproteins. Despite this molecular understanding, therapeutic approaches that target defective FBXW7 have not been identified. Using genome-wide clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 screens, focussed RNA-interference screens and whole and phospho-proteome mass spectrometry profiling in multiple FBXW7 wild-type and defective isogenic cell lines, we identified a number of FBXW7 synthetic lethal targets, including proteins involved in the response to replication fork stress and proteins involved in replication origin firing, such as cell division cycle 7-related protein kinase (CDC7) and its substrate, DNA replication complex GINS protein SLD5 (GINS4). The CDC7 synthetic lethal effect was confirmed using small-molecule inhibitors. Mechanistically, FBXW7/CDC7 synthetic lethality is dependent upon the replication factor telomere-associated protein RIF1 (RIF1), with RIF1 silencing reversing the FBXW7-selective effects of CDC7 inhibition. The delineation of FBXW7 synthetic lethal effects we describe here could serve as the starting point for subsequent drug discovery and/or development in this area.
F -box 和 WD 重复结构域包含 7（FBXW7）肿瘤抑制基因编码 Skp、cullin、F-box（SCF）含有复合物的底物识别亚基。FBXW7 的肿瘤抑制作用归因于其驱动致癌蛋白泛素化和降解的能力。尽管有了这种分子理解，但尚未确定针对缺陷 FBXW7 的治疗方法。我们使用全基因组成簇规律间隔短回文重复 (CRISPR)-Cas9 筛选、集中 RNA 干扰筛选以及多个 FBXW7 野生型和缺陷同基因细胞系的全和磷酸化蛋白质组质谱分析，鉴定了一些 FBXW7 合成致死靶标，包括参与复制叉应激反应的蛋白质和参与复制起始的蛋白质，例如细胞分裂周期 7 相关蛋白激酶 (CDC7)及其底物 DNA 复制复合物 GINS 蛋白 SLD5 (GINS4)。使用小分子抑制剂证实了 CDC7 的合成致死效应。从机制上讲，FBXW7/CDC7 的合成致死性依赖于复制因子端粒相关蛋白 RIF1（RIF1），沉默 RIF1 可逆转 CDC7 抑制对 FBXW7 的选择性影响。我们在这里描述的 FBXW7 合成致死效应的描绘可以作为该领域后续药物发现和/或开发的起点。
