PROTEIN KINASE B PATHWAY IN CELL TRANSFORMATION

已知通过受体酪氨酸激酶的信号传导可启动 许多细胞事件，当解除管制时， 不同的疾病状态，包括癌症。磷酸肌醇3-激酶 （P13 K）已被证明是一个主要的信号蛋白下游的 酪氨酸激酶受体，尽管其直接靶点仍然存在， 难以捉摸。 蛋白激酶B或c-akt是一种原癌基因， 在许多人类肿瘤中扩增，并通过生长激活 P13 K依赖性因素。 P13 K本身也在增加， 卵巢癌的基因拷贝数。 这条途径的重要性 肿瘤的形成被怀疑是由于细胞的增加， 生存，大概是通过磷酸化蛋白BAD， PKB。 最近，我们发现并鉴定了一种新的蛋白质， 磷酸肌醇依赖性激酶-1（PDK-1）， 介导P13 K激活PKB。 P13 K的产物 通过激活PDK-1和启动PKB来激活这一通路， 磷酸化的PDK-1。 这项研究旨在进一步 表征PDK-1在该途径中的作用，以确定其是否 活性以生长因子依赖的方式调节，以观察其 在一组不同的条件下， 条件下，并筛选该激酶的其他底物（Aim 1）。 第二个目标是解决分子内相互作用是否 在非刺激条件下对PKB活性有抑制作用 条件下，并询问是否有其他蛋白质参与PKB activation. 最后，P13 K/PKB通路的活性将被 在许多不同的肿瘤细胞中进行分析，以确定 含有升高活性的肿瘤的比例。 的影响 还将检查抑制该途径的肿瘤发生（目的3）。

Signaling through receptor tyrosine kinases is known to initiate a number of cellular events, and when deregulated are associated with many different disease states including cancer. Phosphoinositide 3-kinase (P13K) has been shown to be a major signaling protein downstream of tyrosine kinase receptors, although its direct targets have remained elusive. Protein kinase B, or c-akt, is a proto-oncogene that is amplified in a number of human tumors, and is activated by growth factors in a P13K-dependent manner. P13K itself is also increased in copy number in ovarian cancers. The importance of this pathway in tumor formation is suspected to be due to increasing cell survival,presumably through phosphorylation of the protein BAD by PKB. Recently, we identified and characterized a novel protein kinase termed phosphoinositide-dependent kinase-1 (PDK-1), which mediates the activation of PKB by P13K. The products of P13K act on this pathway by both activating PDK-1, and priming PKB for phosphorylation by PDK-1. This research proposal seeks to further characterize the role of PDK-1 in this pathway, to determine whether its activity is modulated in a growth factor-dependent manner, to see if its activity is required for PKB activation under a set of different conditions, and to screen for additional substrates of this kinase (Aim 1). The second aim will address whether intramolecular interactions play a role in suppressing the activity of PKB under non-stimulating conditions, and ask whether additional proteins are involved in PKB activation. Finally the activity of the P13K/PKB pathway will be analyzed in a number of different tumor cells to determine the proportion of tumors containing elevated activity. The effect on tumorigenesis of inhibiting this pathway will also be examined (Aim 3).