Prostate carcinogenesis and PKC signaling

描述（由申请人提供）：前列腺癌的发生和进展涉及一系列遗传和表观遗传变化，导致增殖和存活信号失调。人前列腺癌（以及其他几种上皮癌）中的一个显著变化是PKCe的显著过表达，PKCe是一种存活和促有丝分裂的Ser-Thr激酶，是佛波酯肿瘤促进剂的受体。迄今为止，尚不清楚PKCe是否与前列腺癌的病因学有关。目前尚待解决的问题是PKCe过表达与前列腺癌的发生和进展之间是否存在因果关系。我们使用probasin（PB）启动子建立了将PKC同工酶靶向前列腺上皮的小鼠模型。有趣的是，PB-PKCe转基因小鼠前列腺增生和上皮内肿瘤（PIN）病变，而没有观察到明显的表型，在类似的模型，我们开发的PKCa或PKCd过表达。值得注意的是，当我们将PB-PKCe小鼠与杂合Pten小鼠（其也发展癌前病变）杂交时，所得的复合PB-PKCe Pten小鼠发展了浸润性前列腺腺癌。前列腺病变表现为活性Akt、mTOR、S6、Stat 3和NF-kB水平升高。因此，PKCe过表达是前列腺癌发展的潜在致病因素，并与确定的致癌改变合作。在具体目标1中，目标是使用PKCe缺陷型前列腺癌细胞和特异性PKCe抑制剂（eV 1 -2）来确定PKCe是否有助于前列腺癌细胞的致瘤性和扩散。在具体目标2中，我们建议研究PKCe和PI 3 K/Akt轴在前列腺肿瘤发生中的相互需求。我们将产生前列腺特异性PKCe过表达/Akt缺失小鼠模型，以确定Akt是否与PB-PKCe过表达驱动的前列腺病变的形成有关。我们还将检验PKCe的遗传或药理学靶向可以逆转小鼠中Pten缺乏诱导的恶性表型的假设。在具体目标3中，我们将讨论NF-kB在前列腺癌中PKCe信号传导中的潜在参与。NF-kB超活化是前列腺癌的标志，本申请中提供的初步数据显示PKCe和NF-kB途径之间存在明确的功能关系。具体地，在该目的中，我们将a）检查PKCe的过表达是否足以促进正常前列腺上皮细胞中的NF-κ B活化，并与Pten损失协同作用以活化NF-κ B，B）确定PKCe是否涉及在前列腺癌中观察到的NF-κ B的组成性活化，c）表征PKCe参与NF-κ B调节基因的控制，和d）剖析PKCe控制NF-κ B活化的机制。因此，我们的研究将确立PKCe在前列腺癌病因学中的潜在作用，并确定其作为治疗靶点的潜在意义。 公共卫生相关性：在这个应用程序中，我们将表征佛波酯受体，蛋白激酶C β（PKCe）的家庭成员，其参与前列腺癌的发生。我们已经建立了在以前的资助期间，佛波酯，天然化合物，已用于定义的促进阶段，在诱变剂引发的多阶段致癌作用，调节前列腺癌细胞的命运。PKC家族的离散成员在用佛波醇酯激活后可以产生不同的反应。该提案的主要目标是确定PKCe是否与前列腺癌的病因学有关。我们将研究这种佛波酯受体如何与前列腺癌中定义的遗传改变相互作用，并在细胞和动物模型中剖析这些相互作用的机制基础。我们的研究有可能建立一个主要的作用PKCe，促肿瘤受体的佛波醇酯，在前列腺癌的病因，并可能揭示一个新的治疗目标。

DESCRIPTION (provided by applicant): The genesis and progression of prostate cancer involves a series of both genetic and epigenetic changes that result in deregulation of proliferation and survival signals. One notable alteration in human prostate cancer (as well as in several other epithelial cancers) is the marked overexpression of PKCe, a survival and mitogenic Ser-Thr kinase that is a receptor for the phorbol ester tumor promoters. To date it is not known whether PKCe is implicated in the etiology of prostate cancer. The question that remains to be addressed is whether there is a causal relationship between PKCe overexpression and prostate cancer initiation and progression. We generated mouse models to target PKC isozymes to the prostate epithelium using a probasin (PB) promoter. Interestingly, PB-PKCe transgenic mice developed prostatic hyperplasia and intraepithelial neoplastic (PIN) lesions, whereas no obvious phenotype was observed in similar models that we developed for PKCa or PKCd overexpression. Remarkably, when we crossed PB- PKCe mice with heterozygous Pten mice (which also develop preneoplastic lesions), the resulting compound PB-PKCe Pten mice developed invasive prostatic adenocarcinoma. Prostate lesions present elevated levels of active Akt, mTOR, S6, Stat3, and NF-kB. Thus, PKCe overexpression is a potential causative factor for prostate cancer development and cooperates with defined oncogenic alterations. In Specific Aim 1 the goal is to determine whether PKCe contributes to prostate cancer cell tumorigenicity and dissemination, using both PKCe-deficient prostate cancer cells and a specific PKCe inhibitor (eV1-2). In Specific Aim 2 we propose to study the mutual requirement for PKCe and the PI3K/Akt axis in prostate tumorigenesis. We will generate prostate-specific PKCe overexpressing/Akt-null mouse models to determine whether Akt is implicated in the formation of prostate lesions driven by PB-PKCe overexpression. We will also test the hypothesis that genetic or pharmacological targeting of PKCe can reverse the malignant phenotype induced by Pten deficiency in mice. In Specific Aim 3 we will address a potential involvement of NF-kB in PKCe signaling in prostate cancer. NF-kB hyperactivation is a hallmark of prostate cancer, and preliminary data presented in this application show a clear functional relationship between PKCe and NF-kB pathways. Specifically, in this aim we will a) examine if overexpression of PKCe is sufficient to promote NF-kB activation in normal prostate epithelial cells and cooperates with Pten loss to activate NF-kB, b) determine if PKCe is implicated in the constitutive activation of NF-kB observed in prostate cancer, c) characterize the involvement of PKCe in the control of NF-kB-regulated genes, and d) dissect of the mechanisms by which PKCe controls NF-kB activation. Our studies will therefore establish the potential role of PKCe in the etiology of prostate cancer and determine its potential significance as a therapeutic target. PUBLIC HEALTH RELEVANCE: In this application we will characterize a member of the family of phorbol ester receptors, protein kinase C epsilon (PKCe), and its involvement in prostate carcinogenesis. We have established in previous funding periods that phorbol esters, natural compounds that have been instrumental for defining the promotion stage in mutagen-initiated multistage carcinogenesis, regulate prostate cancer cell fate. Discrete members of the PKC family can exert dissimilar responses upon activation with phorbol esters. A main goal in this proposal is to determine whether PKCe is implicated in the etiology of prostate cancer. We will investigate how this phorbol ester receptor interacts with defined genetic alterations in prostate cancer and dissect the mechanistic basis of these interactions both in cellular and animal models. Our studies have the potential to establish a major role for PKCe, a pro-tumorigenic receptor for the phorbol esters, in prostate cancer etiology, and may potentially reveal a novel target for therapy.