RECEPTOR SIGNALING, PHYTIC ACID AND PROSTATE CANCER

拨款的整体目的是进行深入研究，以确定和开发基于分子机制的膳食剂植酸干预人类前列腺癌（PCA）的方法。 表皮生长因子受体家族成员（erbB）的异常表达在前列腺上皮内瘤变和侵袭性人PCA中显示出高频率，表明它们在该疾病的病因中的作用。 除了受体活化之外，配体结合还通过促进受体聚集到膜上网格蛋白包被的凹坑中，随后受体内化，导致受体经由内吞作用从细胞表面快速消失。 包被纹孔的主要结构成分是通过相关蛋白衔接子（Aps）锚定到膜的网格蛋白晶格。 AP 2是最普遍的与erbB受体特异性相互作用的相关蛋白。 除了受体外，另一个步骤是通过P13 K-AKT-Rab 5途径介导的液相内吞作用。 基于受体内吞作用与促有丝分裂和抗凋亡反应之间的高度相关性，我们假设受体介导的和液相内吞作用以及与之相关的促有丝分裂和抗凋亡信号传导的受损是PCA生长抑制/阻滞中的强制性步骤。 为了支持这一假设，我们观察到，内吞作用是在人类PCA细胞的操作，和膳食代理植酸损害内吞作用和有丝分裂反应与it. Together，努力是针对在此授予损害受体内吞信号导致抑制有丝分裂和抗凋亡反应作为一种新的和创新的策略，为干预PCA植酸。使用PCA细胞，我们将评估植酸对1）配体诱导的erbB受体内吞信号传导的抑制作用，并确定AP 2和P13 K-AKT-Rab 5通路在该过程中的参与;以及2）响应于受体内吞信号传导受损的MAPK介导的生长和P13 K-AKT-BAD介导的抗凋亡通路。 接下来，我们将使用体外和体内系统评估植酸对人PCA细胞的生长抑制和/或凋亡性死亡的生物学意义，并定义上述分子事件的参与。 这些研究的结果将为未来的长期研究奠定基础，以a）进一步确定受体内吞信号传导和相关事件在人类PCA中作为干预分子靶点的作用，和B）在调查性临床试验和相关实验室研究中评估植酸对PCA的作用。

Overall goal of the grant is to conduct in depth studies to identify and develop molecular-mechanism based intervention approach for human prostate cancer (PCA) by a dietary agent phytic acid. Aberrant expression of epidermal growth factor receptor family members (erbB) is shown with high frequency in prostatic intraepithelial neoplasia and invasive human PCA suggesting their role in the causation of this disease. In addition to receptor activation, ligand binding also results in a rapid disappearance of receptor from cell surface via endocytosis by promoting receptor clustering into clathrin- coated pits on membrane followed by receptor internalization. A main structural component of coated pits is clathrin lattice anchored to membrane by associated protein adaptors (Aps). AP2 is the most ubiquitous of associated proteins that specifically interact with erbB receptors. In addition to receptor, the other step is fluid-phase endocytosis mediated via P13K-AKT-Rab5 pathway. Based on high association between receptor endocytosis and mitogenic and anti-apoptotic responses, we hypothesize that impairment of both receptor-mediated and fluid-phase endocytosis, and the mitogenic and anti-apoptotic signaling associated with them is an obligatory step in the inhibition/retardation of PCA growth. In support of this hypothesis, we observed that endocytosis is operational in human PCA cells, and that a dietary agent phytic acid impairs endocytosis and mitogenic responses associated with it. Together, efforts are directed in this grant to impair receptor endocytosis signaling leading to inhibition of both mitogenic and anti-apoptotic responses as a novel and innovative strategy for the intervention of PCA by phytic acid. Using PCA cells, we will assess the inhibitory effect of phytic acid on 1) ligand-induced erbB receptor endocytosis signaling, and define the involvement of AP2 and P13K-AKT-Rab5 pathways in this process; and 2) MAPK-mediated growth and P13K-AKT-BAD- mediated anti-apoptotic pathways in response to impairment of receptor endocytosis signaling. Next, we will assess the biological significance of phytic acid on growth inhibition and/or apoptotic death of human PCA cells using both in vitro and in vivo systems, and define the involvement of molecular events identified above. The outcome of these studies will build a base for future long term studies to a) further define the role of receptor endocytosis signaling and associated events in human PCA as molecular target(s) for intervention, and b) evaluate the effect of phytic acid against PCA in investigative clinical trials with correlative laboratory studies.