Prostate carcinogenesis and PKC signaling

描述（由申请人提供）：佛博尔酯是具有肿瘤启动子活性的天然化合物，有助于确定诱变剂引发的多阶段癌变的阶段。佛波酯主要通过激活蛋白激酶C （PKC）起作用，PKC是一个丝氨酸-苏氨酸激酶家族，调节参与细胞生长和恶性转化的途径。矛盾的是，尽管它们具有公认的肿瘤启动子活性，但phobol酯可以在许多细胞类型中引起生长抑制或凋亡，这表明单个PKC同工酶具有不同的功能作用。在之前的资助期内，我们确定了佛波酯通过PKC？-诱导的外源性凋亡级联，p38和JNK级联的激活。另一方面，PKC？使前列腺癌细胞在多种死亡刺激下存活，包括磷酯、细胞因子和辐射，并介导前列腺癌细胞的运动，从而突出了个体PKC同工酶的不同生物学作用。这些结果也高度相关，因为PKC？在人类前列腺癌中显著上调，特别是在高级别肿瘤中。毫不奇怪，研究表明PKC？在其他癌症如乳腺癌和肺癌的病因中过度表达。为了解决我们的发现的相关性，我们产生了前列腺特异性转基因小鼠在原（PB）启动子的控制下。而在PB-PKC？还是PB-PKC ?老鼠,PB-PKC ? ?小鼠出现前列腺增生和上皮内肿瘤（PIN）病变。由于Pten缺乏是前列腺癌中一种常见的致癌改变，我们交叉了PB-PKC？杂合Pten小鼠，也会发生肿瘤前病变。值得注意的是,PB-PKC ?;Pten小鼠发生侵袭性前列腺腺癌，磷酸化- akt水平非常高。因此,PKC吗?过度表达赋予生存信号，并可能通过与其他致癌损伤合作参与前列腺癌的病因学。在具体目标1中，目标是确定PKC？对前列腺癌细胞致瘤性和播散的影响-缺乏前列腺癌细胞和特异性PKC？抑制剂(5 v1-2)。在特异性目标2中，我们将对PKC驱动的病变进行分子表征。超表达。我们推测pin和腺癌来自PKC？过表达的前列腺在有丝分裂和/或生存途径中存在主要的失调，希望确定驱动表型的分子信号，包括Akt及其效应物。我们还将检验PKC？过表达导致Pten的基因组不稳定和双等位基因丢失。在特异性目标3中，我们建议生成前列腺特异性PKC？以确定Akt是否参与PB-PKC中前列腺病变的形成。老鼠。我们还将验证PKC5的遗传或药理学靶向可以逆转Pten缺乏引起的小鼠恶性表型的假设。我们的研究有可能确定PKC的主要作用？一种在前列腺癌病因学中具有致瘤性的磷酸酯受体。公共卫生相关性：在本应用中，我们将描述磷酸酯受体家族的一个成员，蛋白激酶C - epsilon （PKC?）及其在前列腺癌发生中的作用。在之前的资助期内，我们已经确定了佛博尔酯，一种天然化合物，在诱变剂引发的多阶段癌变中，对促进阶段起着重要作用，对前列腺癌细胞产生与细胞命运相关的主要影响。我们已经确定PKC家族的单个成员在被磷酸酯激活时可以产生不同的反应。由于PKC同工酶与包括前列腺癌在内的几种类型癌症的病因有关，我们希望确定PKC？前列腺癌的发生。我们将通过细胞和动物模型来研究这种酚酯受体如何与前列腺癌中定义的改变相互作用，以及这些作用的机制基础。我们的研究有可能确定PKC的主要作用？在前列腺癌病因学中，佛波酯的促肿瘤受体，并可能潜在地揭示新的治疗靶点。

DESCRIPTION (provided by applicant): The phorbol esters are natural compounds with tumor promoter activity that have been instrumental to define the stages of mutagen-initiated multistage carcinogenesis. Phorbol esters act primarily through the activation of protein kinase C (PKC), a family of serine-threonine kinases that modulate pathways involved in cell growth and malignant transformation. Paradoxically, despite their well-established tumor promoter activity, phorbol esters can cause growth inhibition or apoptosis in many cell types, suggesting diverse functional roles for individual PKC isozymes. In previous funding periods we established that phorbol esters cause apoptosis in prostate cancer cells via PKC?-induced activation of the extrinsic apoptotic cascade, p38 and JNK cascades. On the other hand, PKC? confers survival to prostate cancer cells against a number of death stimuli, including phorbol esters, cytokines, and radiation, and it mediates prostate cancer cell motility, thus highlighting the dissimilar biological roles of individual PKC isozymes. These results are also highly relevant because PKC? is markedly up-regulated in human prostate cancer, particularly in high-grade tumors. Not surprisingly, studies have implicated PKC? overexpression in the etiology of other cancers such as breast and lung cancer. To address the relevance of our findings we generated prostate-specific transgenic mice under the control of a probasin (PB) promoter. While no obvious phenotype was observed in PB-PKC? or PB-PKC? mice, PB-PKC??mice develop prostatic hyperplasia and intraepithelial neoplastic (PIN) lesions. As Pten deficiency is a common oncogenic alteration in prostate cancer, we crossed PB-PKC? mice with heterozygous Pten mice, which also develop preneoplastic lesions. Remarkably, PB-PKC?;Pten mice developed invasive prostatic adenocarcinoma with very high phospho-Akt levels. Thus, PKC? overexpression confers survival signaling and possibly contributes to the etiology of prostate cancer by cooperating with other oncogenic injuries. In Specific Aim 1 the goal is to determine whether PKC? contributes to prostate cancer cell tumorigenicity and dissemination, using both PKC?-deficient prostate cancer cells and a specific PKC? inhibitor (5V1-2). In Specific Aim 2 we will pursue a molecular characterization of the lesions driven by PKC? overexpression. We speculate that PINs and adenocarcinomas from PKC? overexpressing prostates have major dysregulations in mitogenic and/or survival pathways, and wish to determine the molecular signals driving the phenotypes, including Akt and its effectors. We will also test the hypothesis that PKC? overexpression leads to genomic instability and biallelic loss of Pten. In Specific Aim 3 we propose to generate a prostate-specific PKC? overexpressing/Akt-null mouse model to determine whether Akt is implicated in the formation of prostate lesions in PB-PKC? mice. We will also test the hypothesis that genetic or pharmacological targeting of PKC5 can reverse the malignant phenotype induced by Pten deficiency in mice. Our studies have the potential to establish a major role for PKC?, a pro-tumorigenic receptor for the phorbol esters, in prostate cancer etiology. PUBLIC HEALTH RELEVANCE: In this application we will characterize a member of the family of phorbol ester receptors, protein kinase C epsilon (PKC?), and its involvement in prostate carcinogenesis. In the previous funding period we have established that phorbol esters, natural compounds that have been instrumental for defining the promotion stage in mutagen-initiated multistage carcinogenesis, exert major effects on prostate cancer cells related to cell fate. We have established that individual members of the PKC family can exert dissimilar responses upon activation with phorbol esters. As PKC isozymes have been implicated in the etiology of several types of cancers, including prostate cancer, we wish to determine the contribution of PKC? to prostate carcinogenesis. We will investigate how this phorbol ester receptor interacts with defined alterations in prostate cancer and the mechanistic basis of these effects using cellular and animal models. Our studies have the potential to establish a major role for PKC?, a pro-tumorigenic receptor for the phorbol esters, in prostate cancer etiology, and may potentially reveal a novel target for therapy.