PROTEIN KINASE B PATHWAY IN CELL TRANSFORMATION

已知通过受体酪氨酸激酶的信号转导可启动 细胞事件的数量，当放松管制时，与许多 不同的疾病状态，包括癌症。磷脂酰肌醇3-激酶 (P13K)已被证明是下游的一个主要信号蛋白 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，并被生长所激活 这些因子以P13K依赖的方式存在。P13K本身也在增加 卵巢癌中的拷贝数。这条途径在人类社会中的重要性 肿瘤的形成被怀疑是由于细胞增加所致 存活，推测是通过BAD蛋白的磷酸化 PKB.最近，我们鉴定并鉴定了一种新的蛋白质 被称为磷脂酰肌醇依赖的激酶-1(PDK-1)，它 介导P13K激活PKB。P13K法案的产物 通过激活PDK-1和启动PKB来实现这一途径 PDK-1的磷酸化。这项研究提案旨在进一步 鉴定PDK-1在这一途径中的作用，以确定其 活动是以依赖于生长因子的方式调节的，以查看其 在一组不同的情况下激活PKB需要活动 条件，并筛选该激酶的其他底物(AIM 1)。第二个目标将解决分子内相互作用 在非刺激性条件下发挥抑制PKB活性的作用 条件，并询问是否有更多的蛋白质参与PKB 激活。最后，P13K/PKB通路的活性将是 在一些不同的肿瘤细胞中进行分析以确定 活跃性升高的肿瘤比例。对…的影响 抑制这一途径的肿瘤发生也将被研究(目标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).