Clinical Cooperation Unit Molecular Hematology/Oncology, German Cancer Research Center (DKFZ) and Department of Internal Medicine V, University of Heidelberg; Heidelberg, Germany.
Cell Cycle. 2012 Sep 15;11(18):3492-503. doi: 10.4161/cc.21801. Epub 2012 Aug 16.
Ectopic viral integration site 1 (EVI1), a transcription factor frequently overexpressed in myeloid neoplasias, has been implicated in the generation of malignancy-associated centrosomal aberrations and chromosomal instability. Here, we sought to investigate the underlying cause of centrosome amplification in EVI1-overexpressing cells. We found that overexpression of EVI1-HA in U2OS cells induced supernumerary centrosomes, which were consistently associated with enlarged nuclei or binuclear cells. Live cell imaging experiments identified cytokinesis failure as the underlying cause of this phenotype. In accordance with previous reports, EVI1 overexpression induced a partial cell cycle arrest in G0/1 phase, accompanied by elevated cyclin D1 and p21 levels, reduced Cdk2 activity and activation of the p53 pathway. Supernumerary centrosomes predominantly occurred in resting cells, as identified by low levels of the proliferation marker Ki-67, leading to the conclusion that they result from tetraploidization after cytokinesis failure and are confined to G0/1-arrested tetraploid cells. Depletion of p53 using siRNA revealed that further polyploidization of these cells was inhibited by the p53-dependent tetraploidy checkpoint.
异位病毒整合位点 1（EVI1）是一种在髓系肿瘤中经常过表达的转录因子，它与致瘤性中心体异常和染色体不稳定性的产生有关。在这里，我们试图研究 EVI1 过表达细胞中中心体扩增的潜在原因。我们发现，EVI1-HA 在 U2OS 细胞中的过表达诱导了多余的中心体，这些中心体始终与增大的核或双核细胞相关。活细胞成像实验确定有丝分裂失败是这种表型的潜在原因。与先前的报道一致，EVI1 过表达诱导了 G0/1 期的部分细胞周期阻滞，伴随着细胞周期蛋白 D1 和 p21 水平的升高，Cdk2 活性的降低和 p53 途径的激活。多余的中心体主要发生在静止的细胞中，这是通过增殖标志物 Ki-67 的低水平来确定的，这导致了它们是有丝分裂失败后四倍体化的结果，并局限于 G0/1 期阻滞的四倍体细胞的结论。使用 siRNA 耗尽 p53 表明，这些细胞的进一步多倍化被 p53 依赖性四倍体检查点所抑制。
