A p27kip1-binding Protein, p27RF-Rho, Promotes Cancer Metastasis via Activation of RhoA and RhoC
A p27kip1-binding Protein, p27RF-Rho, Promotes Cancer Metastasis via Activation of RhoA and RhoC
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DOI：
10.1074/jbc.m110.159715
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发表时间：
2011-01-28
影响因子：
4.8
通讯作者：
Seiki, Motoharu
中科院分区：
文献类型：
--
作者：
Hoshino, Daisuke;Koshikawa, Naohiko;Seiki, Motoharu
Rho家族蛋白通过调节肌动蛋白细胞骨架和基因表达来调节多种细胞功能，包括运动和侵袭。Rho蛋白的激活是由多个调控因子以时空方式精确控制的。RhoA和/或RhoC是调节恶性肿瘤细胞转移活性的关键参与者，因此特别感兴趣的是了解这些Rho蛋白的激活是如何控制的。我们最近发现了一种RhoA激活的上游调节因子，p27 RF-Rho（来自RhoA的p27（kip 1）释放因子），其作用是使RhoA从p27（kip 1）的抑制中释放出来。p27（kip 1）在定位于细胞核时是细胞周期调节剂，但当其定位于细胞质时，其结合RhoA并抑制RhoA的活化。在这里，我们表明，小鼠黑色素瘤B16细胞（F10）的转移性变体表现出更高的表达p27 RF-Rho，RhoA和RhoC比非转移性亲本细胞（F0）。将F10细胞注射到小鼠尾静脉中导致转移性肺集落的形成，而使用特异性shRNA序列预先敲低三种蛋白质中的任一种的表达显著降低了转移。p27 RF-Rho调节RhoA和RhoC的活化，从而调节细胞粘附和运动，除了细胞周蛋白水解。通过p27 RF-Rho增强的Rho活性对F10细胞在肺中的倒伏效率具有显著影响，这代表了转移的早期步骤。p27 RF-Rho还调节人黑色素瘤和纤维肉瘤细胞的转移。因此，p27 RF-Rho是RhoA和RhoC的关键上游调节因子，其控制肿瘤细胞的扩散。
Rho family proteins regulate multiple cellular functions including motility and invasion through regulation of the actin cytoskeleton and gene expression. Activation of Rho proteins is controlled precisely by multiple regulators in a spatiotemporal manner. RhoA and/or RhoC are key players that regulate the metastatic activity of malignant tumor cells, and it is therefore of particular interest to understand how activation of these Rho proteins is controlled. We recently identified an upstream regulator of RhoA activation, p27RF-Rho (p27(kip1) releasing factor from RhoA) that acts by freeing RhoA from inhibition by p27(kip1). p27(kip1) is a cell cycle regulator when it is localized to the nucleus, but it binds RhoA and inhibits activation of the latter when it is localized to the cytoplasm. Here, we show that a metastatic variant of mouse melanoma B16 cells (F10) exhibits greater expression of p27RF-Rho, RhoA, and RhoC than the nonmetastatic parental cells (F0). Injection of F10 cells into mouse tail vein resulted in the formation of metastatic lung colonies, whereas prior knockdown of expression of either one of the three proteins using specific shRNA sequences decreased metastasis markedly. p27RF-Rho regulated the activation of RhoA and RhoC and thereby modulated cellular adhesion and motility, in addition to pericellullar proteolysis. The Rho activities enhanced by p27RF-Rho had a marked effect upon efficiency of lodging of F10 cells in the lung, which represents an early step of metastasis. p27RF-Rho also regulated metastasis of human melanoma and fibrosarcoma cells. Thus, p27RF-Rho is a key upstream regulator of RhoA and RhoC that controls spreading of tumor cells.