Novel regulation of the CDK4/Cdh1/Pin1 signaling axis for targeted breast cancer therapies

项目概要/摘要： 后期促进复合物/环体（APC/C）是一种明确的多亚基E3泛素 调节靶向细胞周期调节剂以通过泛素蛋白酶体途径降解的连接酶 (UPP)，促进细胞周期由中期向后期进展，并参与G1期 上维护APC/CE 3连接酶复合物在进化上是保守的，并且依赖于两个接头蛋白， Cdc 20和Cdh 1，识别不同的靶蛋白并调节细胞周期进程。然而，在这方面， 与经历Cdh 1介导的破坏的Cdc 20相比，调节Cdc 20的E3连接酶活性， cdh 1还不太清楚。已有的研究表明，在大肠杆菌中有19个丝氨酸和苏氨酸残基， Cdh 1在体内可被多种激酶磷酸化，表明Cdh 1的磷酸化调节是 复杂得多。在本研究中，我发现CDK 4可以在体外磷酸化Cdh 1， 调节其E3连接酶活性。此外，我们发现CDK 4对Cdh 1的磷酸化作用可以被抑制。 由Pin 1脯氨酸异构酶识别，促进Cdh 1-Pin 1复合物的形成。根据这一 因此，使用CDK 4/6抑制剂或突变磷酸化位点可以破坏Cdh 1-Pin 1 互动因此，Cdh 1可以介导Pin 1的多聚泛素化和降解。因此， 内源性Cdh 1的阻断阻断了Pin 1抑制剂处理诱导的Pin 1降解。重要的是， 在Cdh 1缺失的MEFs中，Pin 1受体诱导的细胞增殖抑制也被消除，这表明 Cdh 1的功能性存在是Pin 1介导的细胞增殖抑制所必需的。在 此外，CDK 4/6抑制剂和Pin 1抑制剂的组合表现出显著增强的抑制作用。 对乳腺癌细胞的影响。在本提案的第一个目的中，我将探索CDK 4激酶在以下方面的作用： 调节Cdh 1的E3连接酶活性（目标#1）。因此，本建议的第二个目标是 探索Cdh 1在介导Pin 1抑制剂治疗诱导的Pin 1蛋白破坏中的潜在作用 (Aim 2）。总之，这些结果暗示了CDK 4/Cdh 1/Pin 1信号轴在调节细胞凋亡中的功能作用。 为CDK 4/6抑制剂和Pin 1抑制剂联合治疗乳腺癌提供理论依据 癌

Project Summary/Abstract: The anaphase-promoting complex/Cyclosome (APC/C) is a well-defined multi-subunit E3 ubiquitin ligase that regulates targeted cell cycle regulators for degradation by the Ubiquitin Proteasome Pathway (UPP), promoting cell cycle progression from metaphase to anaphase and being involved in G1 phase maintenance. The APC/C E3 ligase complex is evolutionarily conserved and relies on two adaptor proteins, Cdc20 and Cdh1, to recognize different target proteins and regulate cell cycle progression. However, compared to Cdc20 that is subjected to Cdh1-mediated destruction, regulation of the E3 ligase activity of Cdh1 is not well known yet. Previous study has shown that there were 19 serine and threonine residues on Cdh1 that can be phosphorylated by multi-kinases in vivo, indicating that the phosphoregulation of Cdh1 is much more complex. In the present proposal, I found that CDK4 can phosphorylates Cdh1 in vitro and modulates its E3 ligase activity. Furthermore, we found that the phosphorylation of Cdh1 by CDK4 can be recognized by the Pin1 proline isomerase, facilitating Cdh1-Pin1 complex formation. In keeping with this notion, employment of the CDK4/6 inhibitor or mutating the phosphorylation sites can disrupt the Cdh1-Pin1 interaction. Consequently, Cdh1 can mediate Pin1 for polyubiquitination and degradation. As such, depletion of endogenous Cdh1 abolished the Pin1 inhibitor treatment induced Pin1 degradation in cells. Importantly, the Pin1 inhibitor-induced cell proliferation suppression was also abolished in Cdh1-null MEFs, suggesting the functional presence of Cdh1 is required for Pin1 inhibitor-induced cell proliferation suppression. In addition, combination of the CDK4/6 inhibitor and Pin1 inhibitor exhibits significantly enhanced suppressing effect in breast cancer cells. In the first Aim of this proposal, I am going to explore the role of CDK4 kinase in regulating the E3 ligase activity of Cdh1 (Aim #1). Therefore, the second Aim in this proposal will be exploring the potential role of Cdh1 in mediating Pin1 inhibitor treatment induced Pin1 protein destruction (Aim 2). Together, these results implicate a functional role of the CDK4/Cdh1/Pin1 signaling axis in regulating cell proliferation, and provide rational for combining the CDK4/6 inhibitor and Pin1 inhibitor to treat breast cancer.