Dependence of Human Colorectal Cells Lacking the FBW7 Tumor Suppressor on the Spindle Assembly Checkpoint.
Dependence of Human Colorectal Cells Lacking the FBW7 Tumor Suppressor on the Spindle Assembly Checkpoint.
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DOI：
10.1534/genetics.115.180653
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发表时间：
2015-11
期刊：
影响因子：
3.3
通讯作者：
Hieter P
中科院分区：
文献类型：
--
作者：
Bailey ML;Singh T;Mero P;Moffat J;Hieter P
FBW 7（F-box and WD repeat domain containing 7），也称为FBXW 7或hCDC 4，是一种在广谱癌细胞类型中突变的肿瘤抑制基因。作为SCF E3泛素连接酶的组分，FBW 7负责特异性识别磷酸化底物，许多对肿瘤进展很重要，并靶向它们进行泛素介导的降解。虽然FBW 7作为肿瘤抑制因子的作用已经得到了很好的证实，但FBW 7突变的癌细胞如何被靶向选择性杀伤的研究较少。为了进一步探索这一点，我们使用WT和FBW 7敲除结直肠细胞系进行了全基因组RNAi筛选，并鉴定了纺锤体组装检查点（SAC）蛋白BUBR 1作为候选合成致死靶点。我们在这里表明，异步FBW 7敲除细胞具有增加的有丝分裂APC/C底物水平，并且不仅对BUBR 1而且对BUB 1和MPS 1（其他已知的SAC组分）的敲除敏感，这表明这些细胞依赖于有丝分裂检查点。与这种依赖性一致，在缺乏FBW 7的细胞中敲低BUBR 1导致显著的细胞非整倍性和p53水平的增加。FBW 7底物cyclin E是与BUBR 1基因相互作用所必需的。相反，建立这种对SAC的依赖需要FBW 7的多种底物的放松管制。我们的工作表明，FBW 7敲除细胞对有丝分裂检查点的依赖性很脆弱，这可能是FBW 7突变癌细胞的一个很好的潜在靶点。
FBW7 (F-box and WD repeat domain containing 7), also known as FBXW7 or hCDC4, is a tumor suppressor gene mutated in a broad spectrum of cancer cell types. As a component of the SCF E3 ubiquitin ligase, FBW7 is responsible for specifically recognizing phosphorylated substrates, many important for tumor progression, and targeting them for ubiquitin-mediated degradation. Although the role of FBW7 as a tumor suppressor is well established, less well studied is how FBW7-mutated cancer cells might be targeted for selective killing. To explore this further, we undertook a genome-wide RNAi screen using WT and FBW7 knockout colorectal cell lines and identified the spindle assembly checkpoint (SAC) protein BUBR1, as a candidate synthetic lethal target. We show here that asynchronous FBW7 knockout cells have increased levels of mitotic APC/C substrates and are sensitive to knockdown of not just BUBR1 but BUB1 and MPS1, other known SAC components, suggesting a dependence of these cells on the mitotic checkpoint. Consistent with this dependence, knockdown of BUBR1 in cells lacking FBW7 results in significant cell aneuploidy and increases in p53 levels. The FBW7 substrate cyclin E was necessary for the genetic interaction with BUBR1. In contrast, the establishment of this dependence on the SAC requires the deregulation of multiple substrates of FBW7. Our work suggests that FBW7 knockout cells are vulnerable in their dependence on the mitotic checkpoint and that this may be a good potential target to exploit in FBW7-mutated cancer cells.