Suppression of centrosome amplification after DNA damage depends on p27 accumulation
Suppression of centrosome amplification after DNA damage depends on p27 accumulation
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DOI：
10.1158/0008-5472.can-05-3250
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发表时间：
2006-04-15
期刊：
影响因子：
11.2
通讯作者：
Miwa, M
中科院分区：
文献类型：
--
作者：
Sugihara, E;Kanai, M;Miwa, M
中心体在细胞分裂、细胞极性和细胞周期进程中起着重要作用。中心体复制主要由细胞周期蛋白依赖性激酶2（CDK 2）/细胞周期蛋白E和细胞周期蛋白A复合物控制，该复合物被CDK抑制剂p21（Cip 1）和P27（Kip 1）抑制。据认为，CDK 2的异常激活诱导中心体扩增，这在广泛的侵袭性肿瘤中经常观察到。我们以前报道过MYCN癌基因的过度表达导致神经母细胞瘤细胞DNA损伤后中心体扩增。我们在这里表明，γ射线照射后的中心体扩增是由MYCN过表达细胞中p27表达的抑制引起的。我们进一步表明，p27（-/-）和p27（-/-）小鼠胚胎成纤维细胞和p27沉默的人类细胞表现出显着增加，在DNA损伤后的中心体扩增。此外，在p27沉默的细胞中经常观察到中心体扩增的异常有丝分裂细胞。作为对DNA损伤的响应，正常细胞中p27的水平逐渐增加，而Skp 2（SCF泛素连接酶复合物的F-box蛋白组分，靶向p27）则减少，这与共济失调毛细血管扩张症突变/p53通路无关。此外，通过Skp 2小干扰RNA处理，MYCN过表达细胞中的p27水平恢复，表明MYCN下调p27是由于Skp 2的高表达。这些结果表明，DNA损伤后p27的积累是抑制中心体扩增所必需的，从而防止染色体不稳定。
The centrosome plays a fundamental role in cell division, cell polarity, and cell cycle progression. Centrosome duplication is mainly controlled by cyclin-dependent kinase 2 (CDK2)/cyclin E and cyclin A complexes, which are inhibited by the CDK inhibitors p21(Cip1) and P27(Kip1). It is thought that abnormal activation of CDK2 induces centrosome amplification that Is frequently observed in a wide range of aggressive tumors. We previously reported that overexpression of the oncogene MYCN leads to centrosome amplification after DNA damage in neuroblastoma cells. We here show that centrosome amplification after gamma-irradiation was caused by suppression of p27 expression in MYCN-overexpressing cells. We further show that p27(-/-) and p27(-/-) mouse embryonic fibroblasts and p27-silenced human cells exhibited a significant increase in centrosome amplification after DNA damage. Moreover, abnormal mitotic cells with amplified centrosomes were frequently observed in p27-silenced cells. In response to DNA damage, the level of p27 gradually increased in normal cells independently of the ataxia telangiectasia mutated/p53 pathway, whereas Skp2, an F-box protein component of an SCF ubiquitin ligase complex that targets p27, was reduced. Additionally, p27 levels in MYCN-overexpressing cells were restored by treatment with Skp2 small interfering RNA, indicating that down-regulation of p27 by MYCN was due to high expression of Skp2. These results suggest that the accumulation of p27 after DNA damage is required for suppression of centrosome amplification, thereby preventing chromosomal instability.