Developing Fisetin for the Managment of Prostate Cancer

描述(申请人提供)：前列腺癌是美国男性中最常见的癌症，也是男性癌症相关死亡的第二大常见原因。尽管预防和治疗方面的进步提高了总体存活率，但仍然需要有效的基于机制的方法来实现前列腺癌管理的长期改善。在许多与前列腺癌发生有关的信号网络中，PTEN/AKT/哺乳动物雷帕霉素靶点(AKT/mTOR)和MAPK通路就是其中之一。值得注意的是，PTEN/AKT/mTOR和MAPK信号通路协同作用促进肿瘤生长和激素难治性疾病的出现。这些观察结果构成了我们的建议的基础，即同时靶向PTEN/Akt/mTOR和MAPK信号通路可能是抑制前列腺上皮内瘤变(PIN)及其向癌症转化的有效策略。根据这一假设和我们对无毒饮食制剂进行化学预防的追求，我们最近对菲斯汀进行了一些新颖和令人兴奋的观察，菲斯汀是一种结构独特的化学物质，属于多酚类黄酮类化合物。非瑟素对前列腺癌PC3细胞的作用可抑制mTOR激酶信号转导。使用一个独特的人类前列腺上皮细胞系家族，模拟前列腺癌发生过程中的多个步骤，我们观察到转化的细胞具有更高的致癌潜力，表现出更高的mTOR信号和对非瑟素诱导的细胞死亡更敏感。更有趣的是，利用分子模拟，我们观察到菲西汀与mTOR分子发生物理相互作用，并以-8Kcal/mol的结合能对接在两个位置。这些观察结果证明，Fisetin作为一种新的mTOR信号复合体抑制物发挥作用，导致细胞死亡。在这项应用中，我们建议利用Fisetin靶向多个信号通路的能力，并使用一个独特的六人前列腺上皮细胞家族在体外和体内使用基因工程Nkx3.1/Pten突变小鼠模型来研究其有效性，该模型概括了人类前列腺癌的许多特征。与当前研究最相关的是，Nkx3.1/Pten突变小鼠在癌症进展过程中显示出AKT/mTOR和MAPK信号的激活。因此，我们认为这些Nkx3.1/Pten小鼠应该提供一个很好的临床前模型来测试同时靶向AKT/mTOR和ERK MAPK信号在前列腺癌发生中的后果。在本应用中，我们将1)确定PTEN/Akt/mTOR和MAPK信号通路的参与，并确定Fisetin在一个独特的模拟前列腺癌发生过程中多步骤参与的人前列腺上皮细胞系中的作用；2)研究饮食中Fisetin的作用以及PTEN/Akt/mTOR和MAPK信号通路在Nkx3.1/Pten小鼠前列腺癌模型中PIN和雄激素依赖型腺癌的发生发展过程中的作用；3)研究Fisetin对去势诱导的雄激素非依赖性前列腺癌的疗效。这项提议的成功完成可能导致非瑟素作为一种新的预防和治疗前列腺癌的药物的开发。 公共卫生相关性：与晚期前列腺癌有关的主要信号网络包括AKT/哺乳动物雷帕霉素靶点(AKT/mTOR)和MAPK通路。联合抑制AKT/mTOR和ERK MAPK信号通路可有效抑制前列腺癌的发生。我们的研究将提供一种无毒饮食成分Fisetin的使用信息，这种成分可以抑制这些信号通路，在辅助环境下预防和可能的治疗前列腺癌。

DESCRIPTION (provided by applicant): Prostate cancer is the most commonly diagnosed cancer and the second most common cause of cancer related deaths among men in the US. Although advances in prevention and treatment have improved overall survival, there remains a clear need for effective mechanism-based approaches that can achieve long-term improvements in the management prostate cancer. Among the many signaling networks that have been implicated in the development of prostate cancer are the PTEN/AKT/mammalian target of rapamycin (AKT/mTOR) and MAPK pathways. Notably, the PTEN/AKT/mTOR and MAPK signaling pathways function cooperatively to promote tumor growth and the emergence of hormone-refractory disease. These observations form the basis of our proposal that simultaneous targeting of the PTEN/Akt/mTOR and the MAPK signaling pathways may be an effective strategy for inhibiting the development of prostatic intraepithelial neoplasia (PIN) and its conversion to cancer. In line with this hypothesis and in our pursuit for non-toxic dietary agents for chemoprevention, we recently made some novel and exciting observations with fisetin, a structurally distinct chemical substance that belongs to the flavonoid group of polyphenols. Treatment of prostate cancer PC3 cells with fisetin resulted in inhibition of mTOR kinase signaling. Using a unique family of human prostate epithelial cell lines that mimic multiple steps in the process of prostate carcinogenesis we observed that transformed cells with increased potential for tumorigenesis exhibit higher mTOR signaling and greater sensitivity to fisetin induced cell death. More interestingly, using molecular modeling we observed that fisetin physically interacts with the mTOR molecule and docks at two sites with a binding energy of -8Kcal/mol. These observations provide evidence that fisetin functions as a novel inhibitor of mTOR signaling complex leading to induction of cell death. In this application we propose to take advantage of fisetin's ability to target multiple signaling pathways and investigate its efficacy in vitro using a unique family of six human prostate epithelial cells and in vivo using a genetically engineered Nkx3.1/Pten mutant mouse model that recapitulates many features of human prostate cancer. Most relevant for the current study, Nkx3.1/Pten mutant mice display activation of AKT/mTOR and MAPK signaling during cancer progression. Therefore, we reasoned that these Nkx3.1/Pten mice should provide an excellent preclinical model to test the consequences of simultaneous targeting of AKT/mTOR and ERK MAPK signaling for prostate tumorigenesis. In this application we will 1) establish the involvement of PTEN/Akt/mTOR and the MAPK signaling pathways and determine the efficacy of fisetin in a unique family of human prostate epithelial cell lines that mimic multiple steps in the process of prostate carcinogenesis, 2) investigate the effects of dietary fisetin and involvement of PTEN/Akt/mTOR and the MAPK signaling pathways during the development of PIN and androgen dependent adenocarcinoma in the Nkx3.1/Pten mouse model of prostate cancer and 3) investigate the efficacy of fisetin against castration induced androgen independent adenocarcinoma in the Nkx3.1/Pten mutant mouse model of advanced prostate cancer. A successful completion of this proposal may result in the development of fisetin as a novel agent for prevention and possibly for the treatment of prostate cancer. PUBLIC HEALTH RELEVANCE: Among the major signaling networks that have been implicated in advanced prostate cancer are the AKT/mammalian target of rapamycin (AKT/mTOR) and MAPK pathways. Combinatorial inhibition of the AKT/mTOR and ERK MAPK signaling pathways is highly effective for inhibition of prostate tumorigenicity. Our studies will provide information on the use of a non-toxic dietary ingredient fisetin which inhibits these signaling pathways for the prevention and possible treatment of prostate cancer in an adjuvant setting.