CXCL13: a mediator of prostate cancer progression

 描述（由申请人提供）：前列腺癌是美国男性癌症相关死亡的第二大原因。大量证据表明蛋白激酶C β（PKC β）与癌症进展有关。PKC β在上皮性癌包括前列腺癌中显著上调，可能反映其参与疾病的病因和进展。我们发现，前列腺特异性PKC β转基因小鼠（PB-PKC β）发展癌前病变（PIN），并显着，他们发展浸润性前列腺癌在Pten单倍缺陷的背景。理解这种协同性的分子基础是高度相关的，因为肿瘤抑制因子Pten（PI 3 K途径的负调节因子）的丧失是前列腺癌的常见改变。我们产生了一些细胞模型重演PKC β过表达和Pten损失，显示增强的生长，运动性和体外侵袭性，并获得裸鼠的致瘤潜力。此外，基因分析和生物信息学分析显示，PKC β过表达/Pten耗尽的细胞显示出人类转移性前列腺癌特有的基因表达模式。我们发现，在这个微阵列分析中的“最高命中”是趋化因子CXCL 13。值得注意的是，PKC β与Pten损失协同作用，强烈诱导CXCL 13 mRNA水平及其释放，并且CXCL 13或其受体（CXCR 5）的RNAi消耗损害PKC β过表达/Pten缺陷细胞增殖和迁移的能力。初步数据还表明，PKC β和PI 3 K是CXCR 5的下游效应子，这表明正放大环可能充当恶性循环。在特定目标1中，我们将使用诱导沉默方法建立CXCL 13：CXCR 5轴在前列腺肿瘤发生中的相关性。将使用免疫活性小鼠和参与CXCL 13产生的淋巴细胞耗竭来检查基质CXCL 13的潜在贡献。此外，将CXCL 13和CXCR 5敲除小鼠与PB-PKC β小鼠杂交，作为评估前列腺病变发展和关键促有丝分裂/存活途径激活中CXCL 13：CXCR 5轴的需求的方法。在具体目标2中，我们将使用前列腺内注射检查CXCL 13：CXCR 5在转移中的作用，并评估该途径在骨转移性播散中的作用。将进行机制研究，以探索Rac（一种小G蛋白）及其交换因子（Rac-GEF）在由PKC β-PI 3 K-CXCL 13-CXCR 5途径驱动的运动/侵袭表型中的潜在相关性。在具体目标3中，我们将重点关注PKC β和PI 3 K诱导CXCL 13的机制，特别是分析Akt、Erk、Stat 3、NF-κ B B和特异性p110 PI 3 Ks在控制CXCL 13产生中的作用。我们还将研究PKC β作为潜在的CXCR 5下游效应子。最后，在具体目标4中，我们将使用大量前列腺癌标本建立PKC β/Pten-CXCL 13相关性在人前列腺肿瘤中的相关性，并评估与疾病进展和复发的相关性。除了机制的影响，拟议的研究可能有重大的预后和个性化的前列腺癌治疗的治疗影响。

 DESCRIPTION (provided by applicant): Prostate cancer is the second leading cause of cancer-related deaths among men in the US. A large body of evidence links protein kinase C epsilon (PKC) to cancer progression. PKC is markedly up-regulated in epithelial cancers, including prostate cancer, potentially reflecting its involvement in the etiology and progression o the disease. We found that prostate-specific PKC transgenic mice (PB-PKC) develop preneoplastic lesions (PINs), and remarkably, they develop invasive prostatic adenocarcinomas in a Pten haplodeficient background. Understanding the molecular basis of this cooperativity is highly relevant, as loss of the tumor suppressor Pten, a negative regulator of the PI3K pathway, is a common alteration of prostate cancer. We generated a number of cellular models recapitulating PKC overexpression and Pten loss, which display enhanced growth, motility, and invasiveness in vitro, and acquire tumorigenic potential in nude mice. Moreover, gene profiling and bioinformatics analysis revealed that PKC overexpressing/Pten depleted cells display a pattern of gene expression distinctive of human metastatic prostate cancer. We found that the "top hit" in this microarray analysis is the chemokine CXCL13. Notably, PKC cooperates with Pten loss to strongly induce CXCL13 mRNA levels and its release, and RNAi depletion of CXCL13 or its receptor (CXCR5) impairs the ability of PKC overexpressing/Pten-deficient cells to proliferate and migrate. Preliminary data also suggest that PKC and PI3K are downstream effectors of CXCR5, suggesting a positive amplification loop that may act as a vicious cycle. In Specific Aim 1, we will establish the relevance of the CXCL13:CXCR5 axis in prostate tumorigenesis using an inducible silencing approach. A potential contribution of stromal CXCL13 will be examined using immunocompetent mice and depletion of lymphocytes involved in CXCL13 production. In addition, knock-out CXCL13 and CXCR5 mice will be crossed with PB- PKC mice as an approach to assess the requirement of the CXCL13:CXCR5 axis in the development of prostate lesions and the activation of key mitogenic/survival pathways. In Specific Aim 2, we will examine the role of CXCL13:CXCR5 in metastasis using intraprostatic injections and also assess the role of this pathway in metastatic dissemination to bone. Mechanistic studies will be pursued to explore the potential relevance of Rac, a small G-protein, and its exchange factors (Rac-GEFs) in the motile/invasive phenotype driven by the PKC-PI3K-CXCL13-CXCR5 pathway. In Specific Aim 3, we will focus on the mechanisms involved in CXCL13 induction by PKC and PI3K, specifically dissecting the roles of Akt, Erk, Stat3, NF-B and specific p110 PI3Ks in controlling CXCL13 production. We will also investigate PKC as a potential CXCR5 downstream effector. Lastly, in Specific Aim 4 we will establish the relevance of the PKC/Pten-CXCL13 association in human prostate tumors using a large collection of prostate cancer specimens, and assess correlations with disease progression and recurrence. In addition to the mechanistic implications, the proposed studies may have major prognostic and therapeutic impact for personalized prostate cancer treatment.