Prostate carcinogenesis and PKC signaling

描述（由申请人提供）：佛波醇酯是具有肿瘤促进活性的天然化合物，有助于确定诱变剂引发的多阶段致癌作用的阶段。佛波酯主要通过激活蛋白激酶C（PKC）发挥作用，PKC是一种丝氨酸-苏氨酸激酶家族，可调节细胞生长和恶性转化相关途径。奇怪的是，尽管它们具有良好的肿瘤促进活性，佛波醇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。在以前的资助期间，我们确定佛波醇酯通过PKC？引起前列腺癌细胞凋亡。诱导外源性凋亡级联、p38和JNK级联的激活。另一方面，PKC？赋予前列腺癌细胞抵抗许多死亡刺激（包括佛波醇酯、细胞因子和辐射）的存活，并且它介导前列腺癌细胞运动，从而突出了单个PKC同工酶的不同生物学作用。这些结果也是高度相关的，因为PKC？在人前列腺癌中，特别是在高级别肿瘤中显著上调。毫不奇怪，研究表明PKC？在其他癌症如乳腺癌和肺癌的病因学中，为了解决我们的研究结果的相关性，我们产生了前列腺特异性转基因小鼠的probasin（PB）启动子的控制下。PB-PKC未观察到明显的表型？还是PB-PKC小鼠PB-PKC？小鼠出现前列腺增生和上皮内肿瘤（PIN）病变。由于Pten缺乏是前列腺癌中常见的致癌改变，我们将PB-PKC？小鼠与杂合子Pten小鼠，其也发展癌前病变。值得注意的是，PB-PKC？Pten小鼠发生具有非常高的磷酸化Akt水平的侵袭性前列腺腺癌。因此，PKC？过表达赋予存活信号，并可能通过与其它致癌损伤协同作用而导致前列腺癌的病因。在具体目标1的目标是确定是否PKC？有助于前列腺癌细胞的致瘤性和传播，使用PKC？缺乏前列腺癌细胞和特定的PKC？抑制剂（5V1 - 2）。在具体目标2，我们将追求的分子特征的病变驱动的蛋白激酶C？过度表达我们推测，PIN和腺癌从PKC？过表达的前列腺在促有丝分裂和/或存活途径中具有严重的失调，并且希望确定驱动表型的分子信号，包括Akt及其效应物。我们还将测试的假设，PKC？过表达导致Pten的基因组不稳定性和双等位基因丢失。在具体目标3中，我们建议产生前列腺特异性PKC？过表达/Akt缺失小鼠模型，以确定Akt是否与PB-PKC前列腺病变的形成有关？小鼠我们还将测试这一假设，即基因或药理学靶向的PKC 5可以逆转恶性表型诱导的Pten缺乏症的小鼠。我们的研究有可能确立PKC？的主要作用，前列腺癌病因学中佛波醇酯的促肿瘤发生受体。公共卫生相关性：在本申请中，我们将描述佛波酯受体家族的一个成员，蛋白激酶C β（PKC？），以及其在前列腺癌发生中的作用。在前一个资助期，我们已经确定，佛波酯，天然化合物，已用于定义在诱变剂引发的多阶段致癌作用的促进阶段，对前列腺癌细胞的细胞命运产生重大影响。我们已经确定，PKC家族的个别成员可以发挥不同的反应后，激活佛波醇酯。由于PKC同工酶与包括前列腺癌在内的几种癌症的病因学有关，我们希望确定PKC的贡献。前列腺癌的发生我们将研究这种佛波酯受体如何与前列腺癌中定义的改变相互作用，以及使用细胞和动物模型的这些作用的机制基础。我们的研究有可能确立PKC？的主要作用，前列腺癌病因学中佛波醇酯的促肿瘤发生受体，并可能揭示新的治疗靶点。

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.