Induction of tetraploidy through loss of p53 and upregulation of Plk1 by human papillomavirus type-16 E6
Induction of tetraploidy through loss of p53 and upregulation of Plk1 by human papillomavirus type-16 E6
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DOI：
10.1038/sj.onc.1209276
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发表时间：
2006-04-01
期刊：
影响因子：
8
通讯作者：
McCance, DJ
中科院分区：
文献类型：
--
作者：
Incassati, A;Patel, D;McCance, DJ
癌细胞对许多抑制未转化细胞生长的信号不敏感。在这里，我们表明，原代人上皮细胞表达人乳头瘤病毒（HPV）16型E6/E7绕过DNA损伤药物阿霉素引起的逮捕，成为四倍体。为了确定在E7的背景下E6对四倍体的阻滞和诱导的抗性的贡献，我们使用不能降解p53的E6突变体或靶向p53的RNAi进行敲低。E6突变体不能产生四倍体;然而，E7的存在足以绕过停滞，而p53 RNAi允许停滞不敏感性和四倍体。我们以前发表过Polo样激酶1（Plk 1）在表达E6/E7的细胞中上调。我们观察到Plk 1蛋白的异常表达与四倍体相关。使用E6和p53 RNAi的p53结合缺陷突变体，我们表明，p53抑制Plk 1，这表明p53的损失导致四倍体通过上调Plk 1。与这一假设相一致，Plk 1在细胞中的过表达产生四倍体，但不赋予逮捕的阻力。这些结果支持了HPV-16引起的转化模型，其中绕过停滞和四倍体是p53丢失的可分离后果，Plk 1仅用于后一种效果。
Cancer cells are insensitive to many signals that inhibit growth of untransformed cells. Here, we show that primary human epithelial cells expressing human papillomavirus (HPV) type-16 E6/E7 bypass arrest caused by the DNA-damaging drug adriamycin and become tetraploid. To determine the contribution of E6 in the context of E7 to the resistance of arrest and induction of tetraploidy, we used an E6 mutant unable to degrade p53 or RNAi targeting p53 for knockdown. The E6 mutant fails to generate tetraploidy; however, the presence of E7 is sufficient to bypass arrest while the p53 RNAi permits both arrest insensitivity and tetraploidy. We published previously that polo-like kinase 1(Plk1) is upregulated in E6/E7-expressing cells. We observe here that abnormal expression of Plk1 protein correlates with tetraploidy. Using the p53 binding-defective mutant of E6 and p53 RNAi, we show that p53 represses Plk1, suggesting that loss of p53 results in tetraploidy through upregulation of Plk1. Consistent with this hypothesis, overexpression of Plk1 in cells generates tetraploidy but does not confer resistance to arrest. These results support a model for transformation caused by HPV-16 where bypass of arrest and tetraploidy are separable consequences of p53 loss with Plk1 required only for the latter effect.