Induction of p21 by p53 following DNA damage inhibits both Cdk4 and Cdk2 activities
Induction of p21 by p53 following DNA damage inhibits both Cdk4 and Cdk2 activities
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DOI：
10.1038/sj.onc.1208474
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发表时间：
2005-04-21
期刊：
影响因子：
8
通讯作者：
Kuang, J
中科院分区：
文献类型：
--
作者：
He, GG;Siddik, ZH;Kuang, J
DNA 损伤通常会激活 p53-p21 通路并导致哺乳动物细胞中的 G(1) 期停滞。尽管有充足的证据表明 p53 诱导 p21 导致 Cdk2 抑制，但尚不清楚该检查点事件是否也会导致 Cdk4 抑制。二氨基环己烷(反式二乙酸基)(二氯)铂(IV) (DAP)是一种铂基配位络合物，是一种DNA损伤剂，可有效对抗多种对母体药物顺铂耐药的肿瘤细胞。我们之前的研究表明，用低有效浓度的 DAP 治疗人类癌细胞会特异性激活 G(1) 相检查点，同时抑制 Cdk4 和 Cdk2 活性。在此，我们证明 DAP 治疗人类癌细胞可激活 p53-p21 通路，而不会激活抑制 Cdk4 和 Cdk2 活性的其他已知机制。诱导的 p21 与 Cdk4/细胞周期蛋白 D 和 Cdk2/细胞周期蛋白 E 复合物结合，并抑制它们的激酶活性。相反，放线菌酮或 p21 基因缺失对 p21 诱导的抑制可防止 DAP 诱导的 Cdk4 和 Cdk2 活性抑制。 p53 表达和 p21 诱导减弱还可消除 DAP 诱导的 G(1) 期停滞以及 Cdk4 和 Cdk2 活性的抑制。总之，这些发现证实 p53-p21 通路的激活负责 DAP 诱导的 G(1) 期检查点反应，并提供了第一个确凿的证据，表明在 DNA 损伤诱导的 G(1) 期检查点反应期间，p53 诱导 p21 抑制 Cdk4 和 Cdk2 活性。
DNA damage often activates the p53-p21 pathway and causes G(1)-phase arrest in mammalian cells. Although there is ample evidence that p21 induction by p53 leads to Cdk2 inhibition, it is unclear whether this checkpoint event also leads to Cdk4 inhibition. Diaminocyclohexane(trans-diacetato)(dichloro) platinum(IV) (DAP), a platinum-based coordination complex, is a DNA-damaging agent that is effective against a variety of tumor cells resistant to the parental drug cisplatin. Our previous studies established that treatment of human cancer cells with low effective concentrations of DAP specifically activates the G(1)-phase checkpoint and simultaneously inhibit Cdk4 and Cdk2 activities. Here we demonstrate that DAP treatment of human cancer cells activates the p53-p21 pathway without activating other known mechanisms that inhibit Cdk4 and Cdk2 activities. The induced p21 binds to both the Cdk4/cyclin D and Cdk2/cyclin E complexes and inhibits both of their kinase activities. Conversely, inhibition of p21 induction by cycloheximide or by p21 gene deletion prevents DAP-induced inhibition of Cdk4 and Cdk2 activities. Attenuated p53 expression and p21 induction also eliminates DAP-induced G(1)-phase arrest and inhibition of Cdk4 and Cdk2 activities. Together, these findings establish that activation of the p53-p21 pathway is responsible for the DAP-induced G(1)-phase checkpoint response and provide the first solid evidence that p21 induction by p53 during a DNA damage-induced G(1)-phase checkpoint response inhibits both Cdk4 and Cdk2 activities.