Dietary prevention of prostate cancer

描述（由申请人提供）：我们的研究重点是具有癌症化疗和/或化学预防特性的天然化合物。在本研究中，我们将对在亚洲和非洲传统医学中广泛使用的Withania somnifera的生物活性化合物Withaferin-A （WA）的作用机制进行表征。WA对雄激素依赖型和雄激素非依赖型前列腺癌（分别为ADPC和AIPC）显示出令人印象深刻的选择性活性，其中后者对所有当前形式的治疗都是难治的。我们在体外和体内的初步数据表明，WA通过抑制Akt（一种激活细胞存活途径的蛋白激酶）的活性来靶向ADPC和AIPC细胞。我们的初步数据表明，在ADPC和AIPC细胞中，WA激活FOXO3a，进而激活前列腺凋亡反应-4 (Par-4)，这是一种选择性诱导癌细胞凋亡的蛋白。基于我们的研究结果，我们假设WA覆盖了Akt对CREB/Par-4信号传导的负面影响，从而实现对AIPC的化学预防和/或化学治疗作用。为了解决这一假设，我们提出以下目标：研究Akt/CREB与Par-4信号传导之间的相互作用（目的1）；以及WA如何调节AIPC中的促凋亡信号（Aim 2）；在转基因小鼠前列腺腺癌（TRAMP）模型中评估WA对雄激素不依赖型前列腺肿瘤生长的影响（目的3）；并在TRAMP和/或TRAMP细胞系中研究wa介导的肿瘤抑制机制（Aim 4）。对于我们的体外研究，我们将使用多种方法（免疫沉淀、siRNA策略、免疫荧光、Western blot、Northern blots、Chip测定、siRNA策略、拉下测定、药理学阻断）来确定Akt/ creb3a和Par-4聚集的分子连接。在体内研究中，我们将进行肿瘤回归研究，同时我们还将检查组织病理学、细胞死亡、促生存蛋白和促凋亡蛋白在肿瘤组织中的表达模式，以及血清和前列腺组织中的WA水平。我们的长期目标是将天然化合物推广到临床环境中，在那里这些药物可以被彻底评估其化学预防和化学治疗特性。我们的初步数据表明，WA是此类临床评估的潜在候选者，我们提出的研究将从化学预防和化学治疗的角度阐明其在机制水平上对前列腺癌的效力。

DESCRIPTION (provided by applicant): Our research focuses on natural compounds that possess chemotherapeutic and/or chemopreventive properties with respect to cancer. In the proposed study, we will characterize the mechanism of action of the compound Withaferin-A (WA), a bioactive compound of Withania somnifera, which is extensively used in Asian and African traditional medicine. WA displays impressive and selective activity against androgen- dependent and androgen-independent prostate cancer (ADPC and AIPC, respectively), of which the latter is refractory to all current forms of treatment. Our preliminary in vitro and in vivo data indicate WA targets ADPC and AIPC cells by inhibiting the activity of Akt, a protein kinase that activates cell survival pathways. Our preliminary data demonstrate that, concomitant to Akt inhibition in ADPC and AIPC cells, WA activates FOXO3a, which in turn activates prostate apoptosis response-4 (Par-4), a protein that selectively induces apoptosis in cancer cells Based on our results, we hypothesize WA overrides the negative effects of Akt on CREB/Par-4 signaling to achieve chemopreventive and/or chemotherapeutic effects on AIPC. To address this hypothesis, we propose the following aims: investigate the interaction between Akt/CREB and Par-4 signaling, (Aim 1); and how WA modulates the pro-apoptotic signaling in AIPC (Aim 2); evaluate the effects of WA on androgen- -independent prostate tumor growth in the transgenic adenocarcinoma of mouse prostate (TRAMP) model (Aim 3); and examine the mechanisms of WA-mediated tumor inhibition in TRAMP and/or TRAMP cell lines (Aim 4). For the in vitro arm of our studies we will use a variety of approaches (immunoprecipitation, siRNA strategies, immunofluorescence, Western blot, Northern blots, Chip assays, siRNA strategies, pull down assays, pharmacological blocking) in order to determine the molecular junction at which Akt/CREB 3aand Par-4 converge. For our in vivo studies, we will conduct tumor regression studies, yet we will also examine histopathology, cell death, expression patterns of pro-survival proteins and pro-apoptotic proteins in the tumor tissues, and WA levels in the serum and prostate tissue. Our long term goal is to promote natural compounds to a clinical environment, where these agents can be thoroughly assessed for their chemopreventive and chemotherapeutic properties. Our preliminary data indicate WA is a potential candidate for such clinical evaluation, and our proposed studies will elucidate at a mechanistic level its potency against prostate cancer, both from a chemopreventive and chemotherapeutic standpoint.