Role of Sprouty 2 in Hepatocellular Carcinoma

摘要 四种Sprouty蛋白（Spry 1、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。由于其作为RTK介导的抑制剂的作用， 细胞增殖和迁移，Spry蛋白，特别是Spry 2的减少与许多 癌症。因此，现在已经很好地确定，在乳腺、肺、前列腺和前列腺中Spry 2蛋白水平降低， 和肝细胞癌（HCC）。该提案的共同PI表明，在患者来源的HCC中， 在肿瘤中，Spry 2水平的显著降低与患者预后不良相关。此外，在 在这些HCC中，Spry 2水平的降低与Nedd 4 -1水平的升高呈负相关， PI的实验室已经证明了E3泛素连接酶之一，它使Spry 2泛素化，靶向它进行降解。的 PI的实验室还发现，Spry 2蛋白水平可以通过脯氨酰羟基化和von Hippel调节。 Lindau蛋白（pVHL）相关E3连接酶。其他人以及我们表明，pVHL蛋白水平是 在HCC亚群中升高。PI实验室的其他发现表明，Spry 2也是SUMO化的， 这种翻译后修饰增加了其细胞含量。根据这些发现，中心假设 HCC中的Spry 2含量受Nedd 4 -1和/或pVHL介导的调控 遍在化和降解或通过其SUMO化的改变并降低Spry 2含量 HCC升高RTK信号传导，从而增强肿瘤形成和生长。为了解决这个假设， 我们将确定破坏内源性Spry 2/Nedd 4 -1相互作用是否会提高Spry 2含量， 并因此抑制小鼠中HCC细胞的迁移和增殖以及HCC形成的能力。我们 还将确定干扰Spry 2与Spry 2和pVHL的相互作用是否会增强其细胞增殖。 含量，并增强其抑制HCC形成的能力。最后，我们将阐明机制 确定SUMO化是否稳定了Spry 2并调节了它的功能。 在HCC细胞中的生物学作用，并且还确定HCC肿瘤中Spry 2 SUMO化的状态。我们 这些研究不仅将确定Spry 2水平调节的新机制，还将提供见解， 探讨肝癌治疗策略的新可能性。此外，由于Spry 2蛋白质水平 减少乳腺癌，前列腺癌和肺癌，折磨男性和女性退伍军人，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.