Deactivation of Akt by a small molecule inhibitor targeting pleckstrin homology domain and facilitating Akt ubiquitination
Deactivation of Akt by a small molecule inhibitor targeting pleckstrin homology domain and facilitating Akt ubiquitination
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DOI：
10.1073/pnas.1019062108
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发表时间：
2011-04-19
影响因子：
11.1
通讯作者：
Luo, Hongbo R.
中科院分区：
文献类型：
--
作者：
Jo, Hakryul;Lo, Pang-Kuo;Luo, Hongbo R.
普列克底物蛋白同源结构域（PH）的磷脂酰肌醇-3，4，5-三磷酸（PIP 3）结合功能对于致癌Akt/PKB激酶的激活是必需的。在PIP 3介导的膜活化之后，活化的Akt经历其他调节事件，包括泛素化介导的失活。在这里，通过识别和表征变构抑制剂，SC 66，我们表明，促进泛素化有效地终止Akt信号。从机制上讲，SC 66表现出双重抑制活性，直接干扰PH结构域与PIP 3的结合并促进Akt泛素化。一种已知的PH结构域依赖性变构抑制剂，其稳定Akt，防止SC 66诱导的Akt泛素化。癌症相关的Akt 1（e17 k）突变体是不稳定的，使其内在敏感的功能抑制SC 66在细胞环境中，其中PI 3 K抑制几乎没有抑制作用。由于其双重抑制活性，与PIP 3/Akt通路的其他抑制剂相比，SC 66表现出对含有高水平Akt信号传导的转化细胞的更有效的生长抑制。最后，我们通过软琼脂试验以及小鼠异种移植肿瘤模型显示了SC 66的抗癌活性。总之，在这项研究中，我们不仅确定了一个双功能Akt抑制剂，而且还表明，Akt泛素化可以被化学利用，以有效地促进其失活，从而确定了一种途径，药理学干预Akt信号。
The phosphatidylinositol-3,4,5-triphosphate (PIP3) binding function of pleckstrin homology (PH) domain is essential for the activation of oncogenic Akt/PKB kinase. Following the PIP3-mediated activation at the membrane, the activated Akt is subjected to other regulatory events, including ubiquitination-mediated deactivation. Here, by identifying and characterizing an allosteric inhibitor, SC66, we show that the facilitated ubiquitination effectively terminates Akt signaling. Mechanistically, SC66 manifests a dual inhibitory activity that directly interferes with the PH domain binding to PIP3 and facilitates Akt ubiquitination. A known PH domain-dependent allosteric inhibitor, which stabilizes Akt, prevents the SC66-induced Akt ubiquitination. A cancer-relevant Akt1 (e17k) mutant is unstable, making it intrinsically sensitive to functional inhibition by SC66 in cellular contexts in which the PI3K inhibition has little inhibitory effect. As a result of its dual inhibitory activity, SC66 manifests a more effective growth suppression of transformed cells that contain a high level of Akt signaling, compared with other inhibitors of PIP3/Akt pathway. Finally, we show the anticancer activity of SC66 by using a soft agar assay as well as a mouse xenograft tumor model. In conclusion, in this study, we not only identify a dual-function Akt inhibitor, but also demonstrate that Akt ubiquitination could be chemically exploited to effectively facilitate its deactivation, thus identifying an avenue for pharmacological intervention in Akt signaling.