Targets for selenium in prostate cancer prevention

描述(申请人提供)：这项提案测试了一种假设，即天然和合成的有机硒化合物(SEC)通过靶向氧化还原敏感信号蛋白和转录因子，从而调节增殖和/或凋亡反应，从而改变人类前列腺癌(CAP)细胞的生长。抑制细胞增殖和诱导细胞凋亡是SEC的主要抗癌活性。初步研究证明，利用表型相似的雄激素反应(AR+)和无反应(AR-)的人LNCaP细胞，SECS具有选择性生长抑制作用。蛋白质组学研究表明，硒的形态和细胞的激素状态在生长抑制中起着关键作用。为了验证我们的假设，我们制定了3个具体目标。目的1研究SEC对AR+和AR-细胞的抗增殖作用机制。研究将比较SEC在细胞测量、细胞增殖、凋亡过程和细胞内氧化还原环境方面的时间和剂量反应效应。蛋白质组学分析将检查选定的氧化还原敏感信号和转录因子的表达谱。目的2确定SEC和选定的氧化还原信号蛋白之间的相互作用的位置和类型。从增殖和凋亡途径中挑选的纯化或重组蛋白将被研究，以确定是否存在共价的分子内和分子间-S-S-或S-硒偶联物。来自对照和SEC处理的AR+和AR-细胞的类似信号蛋白的免疫沉淀将被研究。蛋白质水解物的高效液相色谱分离和MALDI-TOF MS分析将确定蛋白质修饰的位置。在目标3中，移植了AR+和AR-细胞的裸鼠和流浪鼠分别饲喂含有低水平和高水平SEC(包括硒酵母)的饲料。在这些模型中，目标1中定义的氧化还原敏感信号蛋白的全球表达谱将相对于膳食SEC来确定。这项研究的完成将在蛋白质组水平上确定SEC的分子靶点，并将在AR+和AR-人前列腺癌细胞中鉴定出化学预防作用所需的不同的生理反应。此外，本研究旨在确定Se所处的分子环境是否介导了调节CAP中增殖和/或凋亡过程的氧化还原敏感信号和/或转录因子。这项研究中确定的分子靶标将为正在进行的检查硒蛋氨酸预防CAP的选择性研究提供有用的相关生物标记物。我们的建议确定了各种形式的硒(天然和合成的)在与人类前列腺癌发生有关的蛋白质靶点上的作用。我们研究的长期目标是设计适当的饮食策略来预防前列腺癌。

DESCRIPTION (provided by applicant): This proposal tests the hypothesis that naturally-occurring and synthetic organoselenium compounds (SeC) modify growth of human prostate cancer (CaP) cells by targeting redox sensitive signal proteins and transcription factors thereby regulating proliferative and/or apoptotic responses. Inhibition of cell proliferation and induction of apoptosis are major cancer preventive activities of SeC. Preliminary studies document selective growth inhibitory effects of SeCs utilizing phenotypically similar androgen-responsive (AR+) and - non-responsive (AR-) human LNCaP cells. Proteomic studies reveal that the form of Se and the cell's hormonal status play critical roles in growth inhibition. To test our hypothesis we formulated 3 specific aims. Aim 1 characterizes antiproliferative mechanisms of SeC in AR+ and AR- cells. Studies will compare time and dose-response effects of SeC on cytometric measurements, cell proliferation, apoptotic_processes, and intracellular redox environment. Proteomic analyses will examine expression profiles of selected redox sensitive signal and transcription factors. Aim 2 identifies sites and characterizes the type of interaction between SeC and selected redox signal proteins. Purified or recombinant proteins selected from prolifiterative and apoptotic pathways will be studied to identify occurrences of covalent intra- and intermolecular -S-S- or S- Se conjugates. Immunoprecipitations of similar signal proteins from control and SeC-treated AR+ and AR- cells will be studied. HPLC separation of proteolytic digests followed by MALDI-TOF MS analyses will locate sites of protein modification. In Aim 3, nude mice implanted with AR+ and AR- cells and TRAMP mice are fed diets containing low and high levels of SeC (including selenized yeast). Global expression profiles of redox-sensitive signal proteins as defined in Aim 1 will be determined relative to dietary SeC in these models. Completion of this study will define the molecular targets of SeC at the proteomic level and will identify in AR+ and AR- human prostate cancer cells distinct physiological responses necessary for chemopreventive action. Also, this study aims to determine whether the molecular environment in which Se resides mediates redox sensitive signal and/or transcription factors that regulate proliferative and/or apoptotic processes in CaP. Molecular targets identified in this study will provide relevant biomarkers useful for the on-going SELECT Study that examines selenomethionine for prevention of CaP. Our proposal determines the role of various forms of selenium (natural and synthetic) on protein targets implicated in development of human prostate cancer. The long-term goal of our reseach is to design appropriate dietary strategies for prevention of prostate cancer.