ErbB2 potentiates breast tumor proliferation through modulation of p27Kip1-Cdk2 complex formation:: Receptor overexpression does not determine growth dependency
ErbB2 potentiates breast tumor proliferation through modulation of p27Kip1-Cdk2 complex formation:: Receptor overexpression does not determine growth dependency
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DOI：
10.1128/mcb.20.9.3210-3223.2000
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发表时间：
2000-05-01
影响因子：
5.3
通讯作者：
Hynes, NE
中科院分区：
文献类型：
--
作者：
Lane, HA;Beuvink, I;Hynes, NE
ErbB2 受体（ErbB 受体信号网络的主要组成部分）的过度表达有助于许多人类癌症的发展，因此 ErbB2 成为抗体介导疗法的靶标。在这方面，抗ErbB2单克隆抗体4D5特异性抑制过表达ErbB2的肿瘤细胞的生长。我们分析了 4D5 介导的 ErbB2 抑制对乳腺肿瘤 BT474 细胞周期的影响。 BT474 细胞的 4D5 处理导致 G(1) 停滞，随后 ErbB2 快速去磷酸化、细胞质信号转导途径受到抑制、细胞周期蛋白依赖性激酶抑制剂 p27(Kip1) 积累以及细胞周期蛋白-Cdk2 复合物失活。时间进程表明，4D5 治疗将 p27(Kip1) 重定向到 Cdk2 复合物上，这是 p27(Kip1) 表达增加之前的事件；这与 c-Myc 和 D 型细胞周期蛋白（参与 p27(Kip1) 隔离的蛋白质）的下调以及 Cdk4 复合物中 p27(Kip1) 的丢失有关。在 ErbB2 过表达的 SKBR3 细胞中观察到类似的事件，该细胞在 4D5 处理后表现出增殖减少。此处，p27(Kip1) 重新分布导致部分 Cdk2 失活，与 G1 积累一致。此外，p27（Kip1）蛋白水平保持恒定。反义介导的 4D5 处理的 BT474 细胞中 p27(Kip1) 表达的抑制进一步证明，在没有 p27(Kip1) 积累的情况下，p27(Kip1) 重定向到 Cdk2 复合物足以使 Cdk2 失活并建立 G(1) 阻滞。这些数据表明，ErbB2 过表达通过调节 p27(Kip1) 隔离蛋白导致细胞周期蛋白 E-Cdk2 活性增强，从而解除 G(1)/S 转换的调节。此外，通过与对 4D5 处理不敏感的 ErbB2 过表达细胞系进行比较，我们证明了这些细胞周期事件的特异性，并表明仅 ErbB2 过表达不足以确定细胞对受体抑制的反应。
Overexpression of the ErbB2 receptor, a major component of the ErbB receptor signaling network, contributes to the development of a number of human cancers, ErbB2 presents itself therefore, as a target for antibody-mediated therapies. In this respect, anti-ErbB2 monoclonal antibody 4D5 specifically inhibits the growth of tumor cells overexpressing ErbB2. We have analyzed the effect of 4D5-mediated ErbB2 inhibition on the cell cycle of the breast tumor fell line BT474. 4D5 treatment of BT474 cells resulted in a G(1) arrest, preceded by rapid dephosphorylation of ErbB2, inhibition of cytoplasmic signal transduction pathways, accumulation of the cyclin-dependent kinase inhibitor p27(Kip1), and inactivation of cyclin-Cdk2 complexes. Time courses demonstrated that 4D5 treatment redirects p27(Kip1) onto Cdk2 complexes, an event preceding increased p27(Kip1) expression; this correlates with the downregulation of c-Myc and D-type cyclins (proteins involved in p27(Kip1) sequestration) and the loss of p27(Kip1) from Cdk4 complexes. Similar events were observed in ErbB2-overexpressing SKBR3 cells, which exhibited reduced proliferation in response to 4D5 treatment. Here, p27(Kip1) redistribution resulted in partial Cdk2 inactivation, consistent with a G1 accumulation. Moreover, p27(Kip1) protein levels remained constant. Antisense-mediated inhibition of p27(Kip1) expression in 4D5-treated BT474 cells Further demonstrated that in the absence of p27(Kip1) accumulation, p27(Kip1) redirection onto Cdk2 complexes is sufficient to inactivate Cdk2 and establish the G(1) block. These data suggest that ErbB2 overexpression leads to potentiation of cyclin E-Cdk2 activity through regulation of p27(Kip1) sequestration proteins, thus deregulating the G(1)/S transition. Moreover, through comparison with an ErbB2-overexpressing cell line insensitive to 4D5 treatment, we demonstrate the specificity of these cell cycle events and show that ErbB2 overexpression alone is insufficient to determine the cellular response to receptor inhibition.