Effectors of protein kinase C-mediated tumor progression

 描述(申请人提供)：这项申请集中在一种新的信号链上，该信号链可能对前列腺癌的化学预防和个性化治疗具有重要意义。具体地说，我们确定了致癌蛋白激酶Cε和诱导性环氧合酶-2(COX-2)之间的功能联系。研究表明，COX-2在原发肿瘤中的上调、转移的发展和患者的不良生存之间存在明显的关联。有重要证据表明，用非类固醇抗炎药抑制COX亚型可降低人类癌症的风险。此外，在小鼠模型中，COX-2抑制剂抑制前列腺癌细胞的增殖和触发细胞凋亡，并损害前列腺癌的生长。PKCε在前列腺癌和其他癌症中显著上调，它控制着ERK、Akt、Stat-3和NF-κB等关键的有丝分裂/存活通路。我们建立了一种前列腺特异性的PKCε转基因小鼠模型(PB-PKCε)，它会发展成前列腺癌上皮内瘤变(PIN)。最值得注意的是，在Pten缺失(+/-)的背景下，PKCε转基因小鼠发生侵袭性前列腺癌，Akt和NF-κB过度激活，COX-2上调。前列腺癌上皮细胞模型被设计来概括PKCε过度表达和Pten缺失(即PI3K过度激活)，在裸鼠体内获得致瘤潜力，变得高度侵袭，表现出COX-2上调和PGE 2产生增加(这与前列腺癌有关)，并对COX-2抑制剂的杀伤作用变得高度敏感。在特定的目的1中，主要目的是通过多种方法确定COX-2是否介导了PKCε驱动的肿瘤发生，包括在PKCε表达/Pten缺失的细胞中COX-2shRNA沉默，用COX-2抑制剂治疗PB-PKCε小鼠，以及在PKCε过表达的背景下建立前列腺特异性COX-2基因缺失的小鼠模型。在特定的目标2中，我们将剖析我们最近发现的PKCε和可诱导的前列腺素E 2合成酶mPGES-1之间的联系的功能相关性。将产生前列腺特异性蛋白激酶Cε在mPGES-1缺失背景下过度表达的双重小鼠模型。PGE2(EP)受体在驱动自分泌致癌“恶性循环”中的作用将被机械地剖析。在特定的目标3中，我们将检验特定的p110PI3K亚型介导COX-2/mPGES-1/PGE_2在前列腺模型中的诱导以及由PKCε过表达/Pten缺失所驱动的肿瘤表型。最后，为了增加我们的研究的预后和翻译价值，在特定的目标4中，我们将利用大量的人类前列腺癌标本来确定PKCε的过度表达与COX-2/mPGES-1的诱导之间是否存在相关性。将使用不同Gleason分级、前列腺切除术后疾病复发和去势抵抗(CRPC)疾病的样本。除了重要的机制、预后和治疗意义外，我们的研究还可能为使用COX-2/mPGES-1/EP受体途径抑制剂预防和治疗具有明确致癌改变的前列腺癌患者亚组提供原则证据。

 DESCRIPTION (provided by applicant): This application focuses on a novel signaling link that could have significant implications for chemoprevention and personalized therapy for prostate cancer. Specifically, we identified a functional link between the oncogenic kinase PKCε and inducible cyclooxygenase-2 (COX-2). Studies demonstrated a clear association between COX- 2 up-regulation in primary tumors, development of metastasis, and poor patient survival. There is significant evidence that inhibition of COX isoforms with non-steroidal anti-inflammatory drugs reduces risk of human cancers. In addition, COX-2 inhibitors inhibit proliferation and trigger apoptosis in prostate cancer cells, and impair prostate tumor growth in mouse models. PKCε is markedly up-regulated in prostate cancer and other cancers, and it controls key mitogenic/survival pathways such as Erk, Akt, Stat-3 and NF-κB. We generated a prostate-specific transgenic mouse model for PKCε (PB-PKCε), which develops prostatic intraepithelial neoplasia (PIN) lesions. Most remarkably, in a Pten-deficient (+/-) background, PKCε transgenic mice develop invasive prostate adenocarcinomas with Akt and NF-κB hyperactivation, and COX-2 up-regulation. Prostate epithelial cellular models engineered to recapitulate PKCε overexpression and Pten loss (i.e. PI3K hyperactivation) acquire tumorigenic potential in nude mice, become highly invasive, display COX-2 up- regulation and elevated PGE2 production (which has been linked to prostate cancer), and become highly sensitive to the killing effect of a COX-2 inhibitor. In Specific Aim 1 the main goal is to determine if COX-2 mediates PKCε-driven tumorigenesis using a number of approaches, including COX-2 shRNA silencing in PKCε expressing/Pten depleted cells orthotopically implanted in mouse prostates, treatment of PB-PKCε mice with COX-2 inhibitors, and the generation of a mouse model for prostate-specific COX-2 gene deletion in the context of PKCε overexpression. In Specific Aim 2 we will dissect the functional relevance of a link we recently identified between PKCε and the inducible PGE2 synthase mPGES-1. A dual mouse model for prostate specific PKCε overexpression in a mPGES-1-null background will be generated. The role of PGE2 (EP) receptors in driving an autocrine tumorigenic "vicious cycle" will be mechanistically dissected. In Specific Aim 3 we will test the hypothesis that specific p110 PI3K isoforms mediate COX-2/mPGES-1/PGE2 induction in prostate models and the tumorigenic phenotype driven by PKCε overexpression/Pten loss. Finally, to add prognostic and translational value to our studies, in Specific Aim 4 we will take advantage of a large collection of human prostate cancer specimens to determine if correlations exist between PKCε overexpression and COX-2/mPGES-1 induction. Samples with different Gleason grades, disease recurrence after prostatectomy, and castration-resistant (CRPC) disease will be used. In addition to the significant mechanistic, prognostic and therapeutic implications, our studies may provide proof-of-principle for the use of inhibitors of the COX-2/mPGES-1/EP receptor pathway for the prevention and treatment of subsets of prostate cancer patients with defined oncogenic alterations.