Targets for selenium in prostate cancer prevention

描述（由申请人提供）：该提案测试了天然存在的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/或凋亡反应来改变人前列腺癌（CaP）细胞生长的假设。抑制细胞增殖和诱导细胞凋亡是SeC的主要癌症预防活性。初步研究记录了SeCs利用表型相似的雄激素响应性（AR+）和非响应性（AR-）人LNCaP细胞的选择性生长抑制作用。蛋白质组学研究表明，硒的形式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，我们制定了三个具体目标。目的1研究SeC在AR+和AR-细胞中的抗增殖机制。研究将比较SeC对细胞计数测量、细胞增殖、凋亡过程和细胞内氧化还原环境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确定的网站和特征之间的相互作用的类型SeC和选定的氧化还原信号蛋白。将研究选自增殖和凋亡途径的纯化或重组蛋白，以鉴定共价分子内和分子间-S-S-或S-Se缀合物的发生。将研究来自对照和SeC处理的AR+和AR-细胞的类似信号蛋白的免疫沉淀。HPLC分离蛋白水解酶，然后进行MALDI-TOF MS分析，将定位蛋白质修饰的位点。在目标3中，向植入AR+和AR-细胞的裸鼠和TRAMP小鼠喂食含有低水平和高水平SeC（包括硒化酵母）的饮食。在这些模型中，相对于膳食SeC，将确定目标1中定义的氧化还原敏感信号蛋白的全局表达谱。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化学预防作用所需的不同生理反应。此外，本研究的目的是确定是否硒驻留的分子环境介导的氧化还原敏感的信号和/或转录因子，调节增殖和/或凋亡过程中钙磷。本研究中确定的分子靶点将为正在进行的SELECT研究提供相关生物标志物，该研究检查硒代蛋氨酸预防CaP。我们的建议确定了各种形式的硒（天然和合成）对涉及人类前列腺癌发展的蛋白质靶点的作用。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.