RB silencing compromises the DNA damage-induced G2/M checkpoint and causes deregulated expression of the ECT2 oncogene
RB silencing compromises the DNA damage-induced G2/M checkpoint and causes deregulated expression of the ECT2 oncogene
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DOI：
10.1038/sj.onc.1209810
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发表时间：
2007-01-25
期刊：
影响因子：
8
通讯作者：
Kotani, H.
中科院分区：
文献类型：
--
作者：
Eguchi, T.;Takaki, T.;Kotani, H.
由于视网膜母细胞瘤（RB）/E2F通路的改变在人类癌症中很常见，因此需要广泛研究RB/E2F通路突变引起的细胞周期失调的分子机制。与对 G1-S 细胞周期进程中 RB/E2F 功能的充分了解相比，我们尚不完全了解取消的 RB 途径如何影响细胞周期的 G2-M 期。在这里，我们报告说，在 DNA 损伤存在的情况下，RB 的破坏通过提高一组有丝分裂调节基因的表达来加速 G2-M 进程。我们使用短发夹 RNA 生成 RB(+) 和 (-) 匹配细胞。在 RB(-) 细胞中，由 DNA 损伤剂介导的 G2/M 检查点被覆盖。通过微阵列分析，我们发现RB(-)细胞中关键G2-M调控基因的表达上调。特别是，我们证明了原癌基因 ECT2 直接受 E2F 调控。此外，RB(-)细胞中小干扰RNA抑制ECT2表达导致胞质分裂停滞，表明RB(-)细胞缺乏E2F介导的胞质分裂的调节。这些结果表明，在各种人类肿瘤中观察到的异常 ECT2 表达可能是 RB/E2F 通路缺陷的直接结果，从而导致癌症中的细胞分裂。
As alterations in retinoblastoma (RB)/E2F pathway are commonly found in human cancers, the molecular mechanism underlying cell cycle deregulation caused by the mutations in the RB/E2F pathway needs to be investigated extensively. Compared with good understanding of RB/E2F functions in G1-S cell cycle progression, it is not fully understood how an abrogated RB pathway affects the G2-M phase of the cell cycle. Here, we report that disruption of RB accelerated G2-M progression in the presence of DNA damage by elevating the expression of a set of mitotic regulatory genes. We generated RB(+)- and (-)-matched cells using short hairpin RNA. In the RB(-) cells, the G2/M checkpoint mediated by a DNA-damaging agent was over-ridden. With microarray analysis, we found that the expression of key G2-M regulatory genes was upregulated in RB(-) cells. In particular, we demonstrated that the proto-oncogene ECT2 was directly regulated by E2Fs. Furthermore, suppression of ECT2 expression by small interfering RNA in RB(-) cells resulted in cytokinesis arrest, suggesting that RB(-) cells lack the regulation of E2F-mediated cytokinesis. These results indicate that aberrant ECT2 expression, observed in various human tumors, could be the direct result of RB/E2F pathway deficiency, thereby contributing to cell division in cancers.