Redox Effects of Selenium for Prostate Cancer Prevention

描述（由申请人提供）：最近的研究表明，硒（Se）可降低人类前列腺癌的发病率，并在体外诱导前列腺癌细胞的凋亡和生长抑制。然而，硒的潜在化学预防机制仍不清楚。硒引起的超氧自由基的产生被认为是其潜在的机制之一。我们的研究表明，硒诱导细胞凋亡和生长抑制与超氧自由基的产生和上调p53，p21（Waf 1），Bax，和一些抗氧化酶，这表明还原-氧化（氧化还原）介导的影响硒对p53的激活。因此，我们假设硒诱导前列腺癌细胞的生长抑制和凋亡，部分通过调节细胞的氧化还原状态，导致p53，Bax和p21（Waf 1）的上调和激活。具体目标1是确定硒是否有差异氧化还原作用，在正常的前列腺上皮细胞，永生化上皮细胞，和癌细胞通过测量细胞的抗氧化状态，活性氧水平，和氧化应激硒治疗后。具体目标2是确定超氧自由基的产生是否在硒对p53磷酸化和激活以及随后的细胞生长抑制和凋亡的氧化还原作用中起主要作用，以及线粒体是否是细胞凋亡的主要靶点或途径;这一目标将通过改变超氧物歧化酶（SOD）的水平来测试，使用基因转染和siRNA沉默。超氧阴离子自由基和线粒体SOD 2水平与硒的细胞效应相关。具体目标3是通过基因转染和siRNA沉默来改变p53状态并抑制Bax和p21（Waf 1）通路，以确定p53及其靶基因Bax和p21（Waf 1）在Se诱导的细胞凋亡和细胞周期阻滞中的作用。拟议的研究将提供深入了解硒在前列腺癌化学预防中的机制和分子靶点，并有助于制定预防前列腺癌的特异性和有效的饮食干预策略。

DESCRIPTION (provided by applicant): Recent studies demonstrated that selenium (Se) reduced prostate cancer incidence in humans and induced apoptosis and growth inhibition of prostate cancer cells in vitro. However, the underlying chemopreventive mechanism(s) of Se remains unclear. Production of superoxide radicals by Se has been considered as one of the potential mechanisms. Our studies showed that Se induced cell apoptosis and growth inhibition with superoxide radical production and up-regulation of p53, p21(Waf1), Bax, and some antioxidant enzymes, suggesting a reduction-oxidation (redox)-mediated effect of Se on the activation of p53. Thus, we hypothesize that Se induces growth inhibition and apoptosis of prostate cancer cells in part by modulating cell redox state resulting in upregulation and activation of p53, Bax, and p21(Waf1). Specific Aim 1 is to determine whether Se has differential redox effects in normal prostate epithelial cells, immortalized epithelial cells, and cancer cells by measuring cellular antioxidant status, levels of reactive oxygen species, and oxidative stress following Se treatment. Specific Aim 2 is to determine whether superoxide radical production plays a major role in redox effects of Se on p53 phosphorylation and activation and subsequent cell growth inhibition and apoptosis and whether mitochondria are the primary targets or pathways for cell apoptosis; this aim will be tested by altering levels of superoxide dismutases (SOD) using gene transfection and siRNA silencing. Levels of superoxide radical and mitochondrial SOD2 will be correlated with cellular effects of Se. Specific Aim 3 is to determine the role of p53 and its target genes Bax and p21(Waf1) in Se-induced apoptosis and cell cycle arrest using gene transfection and siRNA silencing to alter p53 status and suppress Bax and p21(Waf1) pathways. The proposed studies will provide insights into the mechanism(s) and molecular targets of Se in prostate cancer chemoprevention and help in the development of specific and effective dietary intervention strategies for prostate cancer prevention.