Developing Fisetin for the Managment of Prostate Cancer

摘要 前列腺癌是最常见的诊断癌症和第二个最常见的癌症原因 美国男性的相关死亡。尽管预防和治疗方面的进展总体上有所改善， 生存，仍然明显需要有效的机制为基础的方法，可以实现长期 改善前列腺癌的治疗。在众多的信令网络中， 与前列腺癌的发展有关的是雷帕霉素的PTEN/AKT/哺乳动物靶点 (AKT/mTOR）和MAPK通路。值得注意的是，PTEN/AKT/mTOR和MAPK信号传导通路起作用， 协同促进肿瘤生长和肿瘤难治性疾病的出现。这些观察结果 形成了我们提出的同时靶向PTEN/Akt/mTOR和MAPK信号转导的基础， 可能是抑制前列腺上皮内瘤（PIN）发展的有效策略 以及它转化为癌症的过程根据这一假设，在我们追求无毒的饮食制剂， 我们最近对非瑟酮进行了一些新的和令人兴奋的观察，非瑟酮是一种结构上不同的 属于多酚类黄酮类的化学物质。前列腺癌PC 3细胞的治疗 与非瑟酮的联合作用导致mTOR激酶信号传导的抑制。使用一个独特的人类前列腺上皮细胞家族 我们观察到，模拟前列腺癌发生过程中多个步骤的细胞系， 肿瘤发生潜能增加的细胞表现出更高的mTOR信号传导和对非瑟酮更高的敏感性 诱导细胞死亡。更有趣的是，使用分子模拟，我们观察到非瑟酮物理相互作用 与mTOR分子结合，并在两个位点对接，结合能为-8Kcal/mol。这些观察结果 提供证据表明非瑟酮作为mTOR信号传导复合物的新型抑制剂发挥作用，导致诱导 细胞死亡在本申请中，我们建议利用非瑟酮的能力，以多个信号 途径，并研究其在体外使用独特的六个人前列腺上皮细胞家族的功效， 体内使用基因工程改造的Nkx3.1/Pten突变小鼠模型，该模型重现了 人类前列腺癌。与当前研究最相关的是，Nkx3.1/Pten突变小鼠显示出激活 癌症进展过程中的AKT/mTOR和MAPK信号传导。因此，我们推断这些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信号转导与前列腺肿瘤发生在本申请中，我们将1）建立 PTEN/Akt/mTOR和MAPK信号通路的参与，并确定非瑟酮在 一个独特的人类前列腺上皮细胞系家族，模拟前列腺增生过程中的多个步骤， 2）研究膳食非瑟酮的作用以及PTEN/Akt/mTOR和MAPK的参与 PIN和雄激素依赖性腺癌发生过程中的信号通路 Nkx3.1/Pten小鼠前列腺癌模型和3）研究非瑟酮对抗去势的功效 Nkx3.1/Pten突变小鼠模型中诱导的雄激素非依赖性腺癌 前列腺癌一个成功的完成这一建议可能会导致非瑟酮的发展作为一种新的 用于预防和可能用于治疗前列腺癌的药物。

ABSTRACT 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.