Cancer Chemoprevention by IP6: Efficacy and Mechanism

IP6 的癌症化学预防：功效和机制

• 批准号: 7106165
• 负责人: Rajesh Agarwal
• 金额: $ 26.95万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7106165
• 关键词: apoptosis; athymic mouse; cell cycle; cell cycle proteins; chemoprevention; death; enzyme inhibitors; human; male; model; neoplasm /cancer; prevention; prostate; prostate neoplasms; protein kinase; tissue /cell culture; xenotransplantation

DESCRIPTION (provided by applicant): The central focus of this grant is to generate critical pre-clinical efficacy and mechanism data with IP6 in various available prostate cancer (PCA) animal models that would set the stage for clinical trials in humans suffering with PCA, which is the most frequently diagnosed invasive malignancy and second most common cause of cancer deaths in males in the United States. Overall, PCA growth and progression involve an aberrant cell cycle progression following gradual accumulation of genetic and epigenetic changes over a period of years. Several mechanisms including a decrease in and/or loss of cyclin-dependent kinase inhibitor (CDKI) function contribute to these events, suggesting that an induction in CDKI level and/or gain in its function is one of the most promising approaches for PCA prevention, growth control and/or therapy. Inositol hexaphosphate (IP6) is a nutrient constituting 6.4% (w/w) or even higher levels in most cereals, legumes, nuts, oil seeds and soybean, and also taken orally as an over-the-counter dietary/nutrient supplement for its several health benefits without any known toxicity. In our recent studies, we found that oral feeding of IP6 to nude mice inhibits the growth of human PCA xenograft without toxicity; completed pilot study in TRAMP model also showed prevention in prostate tumorigenesis by IP6. In PCA cell culture, completed studies by us show that IP6 up- regulates CDKI Kip1/p27 and Cip1/p21 levels together with their increased interaction with CDKs causing inhibition in the kinase activity of CDKs and associated cyclins. These effects of IP6 also caused a G1 arrest, strong inhibition of human and rodent PCA cell growth, and induction of their apoptotic death. No such IP6 effects were observed, however, in non-neoplastic human prostate epithelial cells. Additional studies with siRNA showed that IP6-caused G1 arrest in DU145 cells requires up-regulation of p27 and p21. We also observed that IP6 inhibits PI3K-Akt and NF-KB activation in DU145 cells. Based on these studies, our hypothesis is that p27 and p21 induction is required for cell cycle arrest and in part apoptotic death, together with inhibition of PI3K/Akt/NF-kB activation, by IP6 in its cancer chemopreventive efficacy against PCA. To test this hypothesis, we will: 1) Examine IP6 as a preventive agent in mouse TRAMP and MNU-testosterone rat PCA models; II) Examine efficacy of IP6 in growth control and therapy of PCA using ectopic and orthotopic human prostate carcinoma xenografts in male nude mice; III) Define and characterize in vivo efficacy of IPS on cell cycle regulators in tumor tissues, identify and establish CDKI induction as a molecular target of IP6 action using both cell culture and animal models, and define the mechanism of CDKI induction by IP6 in cell culture; and IV) Define and characterize the in vivo efficacy of IP6 on apoptotic pathways, and identify and establish the role of CDKI, and PI3K-Akt and NF-KB pathways in IPG-induced apoptosis using cell culture systems. Overall, proposed studies would further establish preventive and interventive efficacy of IP6 against PCA and define its molecular mechanisms on cell cycle and apoptosis regulation.

描述（由申请人提供）：这笔赠款的主要重点是在各种可用的前列腺癌（PCA）动物模型中生成关键的临床前功效和机制数据，这些模型将为患有PCA的人类患者的临床试验奠定基础，这是最常见的侵入性恶性肿瘤，是美国癌症中癌症死亡的第二常见原因。总体而言，PCA的生长和进展涉及多年来遗传和表观遗传变化逐渐积累后的异常细胞周期进程。几种机制，包括细胞周期蛋白依赖性激酶抑制剂（CDKI）功能的降低和/或丧失有助于这些事件，这表明其功能的诱导和/或获得的诱导是PCA预防，生长控制和/或治疗的最有希望的方法之一。在大多数谷物，豆类，坚果，油籽和大豆中，肌醇六角磷酸（IP6）是一种营养素，构成6.4％（w/w），甚至更高水平，并且在没有任何已知毒性的情况下以多种健康益处而口头作为非处方饮食/营养补充剂。在我们最近的研究中，我们发现对裸鼠的口服喂养抑制了人类PCA异种移植物的生长而无需毒性。在流浪汉模型中完成的试点研究还显示，IP6预防前列腺肿瘤发生。在PCA细胞培养中，美国完成的研究表明，IP6可以调节CDKI KIP1/P27和CIP1/P21水平，以及它们与CDK的相互作用的增加，从而导致CDKS和相关细胞周期蛋白的激酶活性抑制。 IP6的这些影响还引起了G1停滞，对人和啮齿动物PCA细胞生长的强烈抑制以及诱导其凋亡死亡。但是，在非塑性人前列腺上皮细胞中未观察到这种IP6效应。对siRNA的其他研究表明，在DU145细胞中引起的IP6引起的G1停滞需要上调P27和P21。我们还观察到IP6抑制DU145细胞中的PI3K-AKT和NF-KB激活。基于这些研究，我们的假设是，IP6在其癌症化学预防效力中对PCA的癌症化学预防效力，需要P27和P21诱导才能使细胞周期停滞和部分凋亡死亡以及抑制PI3K/AKT/NF-KB激活所必需。为了检验这一假设，我们将：1）检查IP6作为小鼠流浪汉和MNU-Tostosterone大鼠PCA模型中的预防剂； ii）使用异位和原位人前列腺癌异种移植物在雄性裸鼠中检查IP6在PCA生长控制和PCA治疗方面的功效； iii）定义和表征IPS在肿瘤组织中细胞周期调节剂的体内功效，使用细胞培养和动物模型识别并确定CDKI诱导为IP6作用的分子靶标，并定义IP6在细胞培养中IP6诱导CDKI诱导的机制； iv）定义和表征IP6在凋亡途径上的体内疗效，并识别和确定CDKI的作用，以及使用细胞培养系统在IPG诱导的凋亡中PI3K-AKT和NF-KB途径。总体而言，拟议的研究将进一步建立IP6对PCA的预防和干预功效，并在细胞周期和凋亡调节中定义其分子机制。