Role of Sprouty 2 in Hepatocellular Carcinoma

摘要 四种Sprouty蛋白(Spry1、2、3和4)抑制受体酪氨酸激酶(RTK)的生物学作用 从而调节各种器官的发育。因为它们的作用是RTK介导的抑制物 细胞的增殖和迁移，Spry蛋白的减少，特别是SPRY2，已经参与了许多 癌症。因此，现在已经很好地证实，乳腺、肺、前列腺中的SPRY2蛋白水平降低 和肝细胞癌(HCC)。这一提议的联合PI表明，在患者来源的肝癌中 肿瘤，SPRY2水平的显著降低与患者预后不良相关。此外，在一个子集 这些HCCs中，SpRY2水平的降低与Nedd4-1水平的升高呈负相关，Ned4-1的水平 Pi的实验室已经证明，它是一种E3泛素连接酶，可以泛素化SPRY2，使其降解。这个 Pi的实验室还发现，SPRY2蛋白水平可以通过脯氨酸羟化和von Hippel来调节 Lindau蛋白(PVHL)相关的E3连接酶。其他的以及我们显示的pVHL蛋白水平是 在碳氢化合物的亚组中升高。PI实验室的其他发现表明，SPRY2也是SUMO化的， 这种翻译后修饰增加了它的细胞含量。鉴于这些发现，中心假说 这项提案将测试的是，HCCs中的SPRY2含量受Nedd4-1和/或pVHL介导的调节 泛素化和降解或通过其SUMO化的改变和降低SPRY2的含量 肝细胞癌上调RTK信号，从而促进肿瘤的形成和生长。为了解决这一假设， 我们将确定破坏内源性SPRY2/Nedd4-1相互作用是否会增加SPRY2含量 因此，它能够抑制肝癌细胞的迁移和增殖，并抑制小鼠肝癌的形成。我们 也将确定干扰SPRY2与SPRY2和pVHL的相互作用是否会增强其细胞 并增强其抑制肝细胞癌形成的能力。最后，我们将阐明这些机制。 通过SPRY2的SUMO化，确定SUMO化是否稳定SPRY2并调节其 在肝癌细胞中的生物学作用，也决定了SPRY2在肝癌肿瘤中的SUMO化状态。我们的 研究不仅将确定调节SPRY2水平的新机制，而且还将提供见解 探索肝癌治疗策略的新可能性。此外，由于SPRY2蛋白水平是 在困扰男性和女性退伍军人的乳腺癌、前列腺癌和肺癌方面，我们的研究也将 对这些疾病有更广泛的影响。

Abstract The four Sprouty proteins (Spry1, 2, 3, & 4) inhibit the biological actions of receptor tyrosine kinases (RTKs) and thereby regulate the development of various organs. Because of their role as inhibitors RTK- mediated cell proliferation and migration, decrease in Spry proteins, especially Spry2 has been implicated in a number of cancers. Thus, it is now well established that Spry2 protein levels are decreased in breast, lung, prostate and hepatocellular carcinomas (HCC). The co-PI of this proposal has shown that in patient-derived HCC tumors, marked decreases in Spry2 levels correlated with poor patient outcome. Moreover, in a subset of these HCCs, the decreased Spry2 levels inversely correlated with increased levels of Nedd4-1, which the PI's lab has shown is one of the E3 ubiquitin ligases that ubiquitylates Spry2 targeting it for degradation. The PI's lab has also found that Spry2 protein levels can be regulated by prolyl hydroxylation and von Hippel Lindau protein (pVHL)- associated E3 ligase. Others as well as we show that pVHL protein levels are elevated in subsets of HCCs. Additional findings from the PI's lab show that Spry2 is also SUMOylated and this post-translational modification increases its cellular content. Given these findings, the central hypothesis that this proposal will test is that Spry2 content in HCCs is regulated by Nedd4-1- and/or pVHL- mediated ubiquitylation and degradation or via alterations in its SUMOylation and that decreased Spry2 content in HCC elevates RTK signaling, thereby augmenting tumor formation and growth. To address this hypothesis, we will determine whether disrupting the endogenous Spry2/Nedd4-1 interactions enhance Spry2 content and, therefore its ability to inhibit migration and proliferation of HCC cells and HCC formation in mice. We will also determine whether interfering with Spry2 interactions with Spry2 and pVHL enhances its cellular content and also augments its ability to suppress HCC formation. Finally, we will elucidate the mechanisms by which Spry2 is SUMOylated, determine whether SUMOylation stabilizes Spry2 and regulates its biological actions in HCC cells, and also determine the status of Spry2 SUMOylation in HCC tumors. Our studies will not only identify novel mechanisms by which Spry2 levels are regulated but also provide insights into newer possibilities of therapeutic strategies for HCCs. Moreover, since Spry2 protein levels are decreased in breast, prostate, and lung cancer that afflict male and female veterans, our studies will also have a broader impact in these diseases.