Prostate Cancer Metastasis Suppressor: Role of RKIP

描述（由申请人提供）：使用基因阵列，我们已经确定Raf激酶抑制剂蛋白（RKIP）的表达在前列腺癌转移中下调。RKIP抑制JAK/STAT活化和Raf-mediated的MEK/ERK活化。免疫组化证实RKIP存在于正常前列腺和原发性前列腺肿瘤中，但在前列腺癌转移灶中不存在。此外，我们已经证明，用RKIP cDNA转染转移性前列腺癌细胞系可防止鼠模型中的转移，同时对原发性肿瘤的生长速率没有影响，而用反义RKIP转染非转移性前列腺癌细胞系可促进转移。综上所述，这些数据使我们假设RKIP是前列腺癌转移抑制基因，其丢失通过MEK/ERK和JAK/STAT促进转移。为了验证我们的假设，我们将执行以下具体目标：1。确定RKIP在体内的转移抑制活性的程度。使用几种新的前列腺癌细胞系，我们将确定调节RKIP水平对小鼠模型转移的影响。2.确定RKIP失调促进转移的细胞机制。我们将评估操纵RKIP水平对促转移参数（包括血管生成、内皮粘附和侵袭性）的影响。一旦我们基于这些体外研究鉴定出靶分子，我们将在体内使用抑制剂来确定阻断这些活性是否抑制RKIP介导的转移的丧失。3.确定RKIP表达降低介导转移的信号通路。我们将评估调节JAK/STAT和MEK信号通路的活性对体外参数（包括侵袭、增殖和凋亡）的影响。随后，我们将确定对体内转移建立的影响。此外，我们将确定在Aim 2中鉴定的任何促转移细胞表型是否受到这些信号传导途径的调节。当完成后，我们希望这项工作将导致更好地理解RKIP抑制转移的机制，并有希望确定抑制转移的特异性靶点。

DESCRIPTION (provided by applicant): Using a gene array, we have identified that expression of Raf kinase inhibitor protein (RKIP) is down-regulated in prostate cancer metastases. RKIP inhibits JAK/STAT activation and Raf-mediated activation of MEK/ERK. Immunohistochemistry confirmed that RKIP is present in normal prostate and primary prostate tumors, but absent in prostate cancer metastases. Furthermore, we have demonstrated that transfection of a metastatic prostate cancer cell line with RKIP cDNA prevents metastasis in a murine model while having no effect on growth rate of the primary tumor and transfection of a non-metastatic prostate cancer cell line with antisense RKIP promotes metastasis. Taken together, these data lead us to hypothesize RKIP is a prostate cancer metastasis-suppressor gene, whose loss promotes metastasis through MEK/ERK and JAK/STAT. To test our hypothesis, we will perform the following specific aims: 1. Determine the extent of RKIP's metastasis suppressor activity in vivo. Using several novel prostate cancer cell lines we will determine the effect of modulating RKIP levels on metastasis in murine models. 2. Identify the cellular mechanism(s) through which RKIP dysregulation promotes metastasis. We will evaluate the effect of manipulating RKIP levels on pro-metastatic parameters including angiogenesis, endothelial adhesion and invasiveness. Once we identify a target molecule based on these in vitro studies we will use inhibitors in vivo to determine if blocking these activities inhibits loss of RKIP-mediated metastasis. 3.Determine the signaling pathways through which decreased RKIP expression mediates metastasis. We will evaluate the effects of modulating the activities of the JAK/STAT and MEK signaling pathways on in vitro parameters including invasion, proliferation and apoptosis. Subsequently, we will determine the effect on establishment of metastases in vivo. Furthermore, we will determine if any pro-metastatic cellular phenotypes identified in Aim 2 are modulated by these signaling pathways. when completed, we hope this work will lead to a better understanding of the mechanisms through which RKIP suppresses metastasis and hopefully identify specific targets to inhibit metastasis.