Prostate Cancer Prevention by Procyanidins in Grape Seed Extract

描述（由申请人提供）： 前列腺癌（PCA）是老年男性中最常见的恶性肿瘤，被列为男性癌症死亡的第二大原因。恶性肿瘤具有从肿瘤前病变发展到完全发展的癌症的长潜伏期，这提供了充足的时间来采用化学预防策略干预或改变这种疾病的进展。此外，许多研究表明，某些癌症的风险可以通过饮食控制来降低，特别是通过增加水果和蔬菜的消费。因此，人们对确定饮食或饮食成分（营养性和非营养性植物化学物质）作为化学预防剂的潜在用途非常感兴趣。葡萄籽提取物（GSE）是一种丰富的原花青素（也称为原花青素）的商业来源，由于其广泛的有益效果，通常被用作健康补充剂。关于癌症，我们和其他人的几项研究已经证明了GSE对各种上皮恶性肿瘤（包括PCA细胞）的抗癌和化学预防功效。由于GSE代表多酚的复杂混合物，因此在上一个资助期间研究的中心焦点是分离和表征GSE中的活性成分，以使用纯的和确定的试剂进行抗癌活性的详细机制和功效研究。我们最近从GSE中分离并鉴定了原花青素B2- 3，3 '-二-O-没食子酸酯（B2-G2）作为活性化合物，其对人前列腺癌DU 145细胞具有强的抗癌活性。对这种化合物的进一步研究表明，它被PCA细胞吸收，并引起细胞毒性和细胞生长抑制作用。其他研究表明，B2-G2在携带功能性雄激素受体的人PCA细胞中引起细胞周期停滞和凋亡诱导;这些细胞特别代表大多数人前列腺肿瘤。重要的是，B2-G2在正常人前列腺上皮细胞和基质细胞中没有显示出细胞毒性，表明其在人PCA细胞中的选择性。由于由于细胞周期进程失调和凋亡功能丧失导致的不受控制的增殖是包括PCA在内的大多数癌症的主要潜在缺陷，并且由于B2-G2在PCA细胞中发挥强烈的细胞周期停滞和凋亡反应，我们的中心假设是原花青素B2-3，3 '-二-O-没食子酸盐选择性地诱导肿瘤性前列腺上皮细胞的细胞周期停滞和凋亡，这共同导致其预防和治疗前列腺增生的功效。PCA。我们的具体目标是：1）制备计划的机制、生物利用度和功效研究所需的B2-G2，2）进行体外研究以阐明涉及细胞周期停滞和凋亡的B2-G2的作用机制，和3）使用体内转基因小鼠前列腺癌（TRAMP）模型确定B2-G2的功效和生物利用度，所述模型紧密且自然地模拟人类前列腺癌的进展。总体而言，我们的长期目标是开发原花青素B2- 3，3 '-二-O-没食子酸酯作为基于机制的潜在PCA化学预防剂。前列腺癌是美国癌症相关死亡的第二大原因，因此是一个重要的公共卫生问题。使用化学预防剂似乎是控制前列腺癌的更有效方法，因为它具有长的潜伏期发展;有时从前驱病变到完全疾病需要数十年。目前的拨款提案集中在开发这样一种药剂，这种药剂是从葡萄籽提取物中分离出来的，葡萄籽提取物是一种广泛消费的健康补充剂。我们提出的研究结果将为预防人类前列腺癌提供一种基于机制的药物。

DESCRIPTION (provided by applicant): Prostate cancer (PCA) is the most frequently diagnosed malignancy in elderly men, and is rated as second leading cause of cancer deaths in men. The malignancy has long latent period of development from pre-neoplastic lesion to full-blown cancer providing ample time to intervene or alter the progression of this disease employing chemopreventive strategies. Additionally, numerous studies have shown that the risk for certain cancers could be lowered by dietary manipulations, especially by increased consumption of fruits and vegetables. Accordingly, there has been serious interest in identifying diets or dietary constituents (both nutritive and non-nutritive phytochemicals) for their potential use as chemopreventive agents. Grape seed extract (GSE), a rich and commercially available source of proanthocyanidins (also known as procyanidins), is usually consumed as a health supplement for its wide range of beneficial effects. Regarding cancer, several studies by us and others have demonstrated the anti-cancer and chemopreventive efficacy of GSE against various epithelial malignancies including PCA cells. Since GSE represents a complex mixture of polyphenols, the central focus of the studies during the last funding period was to isolate and characterize active component(s) in GSE to carry out detailed mechanistic and efficacy studies for anticancer activity employing pure and defined agents. We recently isolated and characterized procyanidin B2- 3,3'-di-O-gallate (B2-G2) as an active compound from GSE with strong anti-cancer activity against human prostate carcinoma DU145 cells. Further studies with this compound revealed that it is taken up by PCA cells and that it causes both cytotoxic as well as cell growth inhibitory effects. Additional studies revealed that B2-G2 causes both cell cycle arrest and apoptosis induction in human PCA cells carrying functional androgen receptor; these cells specifically represent majority of human prostate tumors. Importantly, B2-G2 did not show cytotoxicity in normal human prostate epithelial and stromal cells, showing its selectivity in human PCA cells. Since uncontrolled proliferation due to deregulated cell cycle progression and loss of apoptotic function are the major underlying defects in most of the cancers including PCA and since B2-G2 exerts strong cell cycle arrest and apoptotic responses in PCA cells, our central hypothesis is that procyanidin B2-3,3'-di-O-gallate selectively induces cell cycle arrest and apoptosis in neoplastic prostate epithelial cells which collectively leads to its preventive and therapeutic efficacy against PCA. Our specific aims are to: 1) prepare B2-G2 needed for planned mechanistic, bioavailability and efficacy studies, 2) conduct in vitro studies to address mechanism of action of B2-G2 involved in cell cycle arrest and apoptosis, and 3) determine efficacy and bioavailability of B2-G2 employing an in vivo transgenic carcinoma of the mouse prostate (TRAMP) model, which closely and naturally mimics the progression of prostatic carcinoma in humans. Overall, our long term goal is to develop procyanidin B2-3,3'-di- O-gallate as a mechanism-based potential chemopreventive agent against PCA. PUBLIC HEALTH RELEVANCE Prostate cancer is second leading cause of cancer-related deaths in United States, and thus is an important public health issue. Use of chemopreventive agents seems to be more effective approach for the control of prostate cancer as it has long latent period of development; sometimes over decades from precursor lesions to full blown disease. Current grant proposal focuses on the development of one such agent, which has been isolated from grape seed extract, a widely consumed health supplement. Outcomes of our proposed research will provide a mechanism-based agent for the prevention of prostate cancer in humans.