PI3K pathway in prostate epithelial transformation

PI3K/PTEN通路是细胞死亡和细胞增殖的重要调节因子。PTEN抑癌基因在相当数量的前列腺癌中发生突变，我们已经证明PTEN蛋白的缺失与高Gleason分级的肿瘤有关。PTEN的缺失会导致Akt激酶的激活。AKT进而磷酸化并抑制一些下游靶标，包括BAD、Caspase 9、GSK-3以及叉头转录因子AFX、FKHRL1和FKHR。初步数据表明，在没有PTEN的情况下，叉头转录因子被解除调控，恢复叉头功能足以抑制PTEN缺失的肿瘤细胞的生长。因此，这些因素可能是PTEN下游生长抑制的关键调节因子。在这项工作的基础上，本项目旨在研究该途径在转化小鼠前列腺上皮细胞中的作用。在目标1中，将使用转基因方法在小鼠前列腺中实现Akt的结构性激活。在前列腺中表达激活Akt的转基因动物将被分析以开发方法。在前列腺中表达激活Akt的转基因动物将被分析为小鼠肿瘤的发展。这些动物将被分析，并与罗伯茨和坎特利实验室购买阵列分析产生的动物进行比较。在这里，我们的目标将是在体内使用转录图谱来剖析这一途径，以确定一致或不同的转录靶点。在目标2中，我们将确定显性负性FKFR是否足以抑制细胞中的FKHR功能，如果是，那么FKHR是否是PTEN调节生长功能所必需的。显性阴性的FKHR将在小鼠的前列腺中表达，以询问抑制FKHR活性是否足以进行转化。在目标3中，我们将与Robert的实验室一起研究这一途径在人类肿瘤中的激活状态，确定PTEN缺失是否伴随着FKHR重新定位到细胞质，通过IGFI-R受体激活，以及细胞周期蛋白依赖的激酶抑制物p27的失控。

The PI3K/PTEN pathway is a critical regulator of cell-death and cellular proliferation. The PTEN tumor suppressor gene is mutated in a significant number of prostate tumors, and we have shown that loss of the PTEN protein is associated with high Gleason grade tumors. PTEN loss leads to activation of the Akt kinase. Akt in turn phosphorylates and inhibits a number of downstream targets including BAD, Caspase 9, GSK-3, and the forkhead transcription factors AFX, FKHRL1 and FKHR. Preliminary data suggests that in the absence of PTEN, forkhead transcription factors are deregulated and that restoring Forkhead function is sufficient to suppress the growth of PTEN null tumor cells. Thus, these factors are likely critical regulators of growth suppression downstream of PTEN. Based upon this work, this project aims to study the role of this pathway in the transforming murine prostate epithelial cells. In aim 1, constitutive activation of Akt in the murine prostate will be achieving using transgenic approaches. Transgenic animals expressing activated Akt in the prostate will be analyzed for the development of approaches. Transgenic animals expressing activated Akt in the prostate will be analyzed for the development of murine tumors. These animals will be analyzed and compared with animals generated by the Roberts and Cantley labs buy array analysis. Here, the goal will be to dissect this pathway in vivo using transcriptional profiling to identify concordant or divergent transcriptional targets. In aim 2, we will determine whether dominant-negative FKFR is sufficient for inhibition of FKHR function in cells and if so, whether FKHR is necessary for PTEN function in regulating growth. Dominant-negative FKHR will be expressed in the murine prostate to ask whether inhibition of FKHR activity is sufficient for transformation. In aim 3, in conjunction with the Robert's lab we will study the activation status of this pathway in human tumors do determine whether PTEN loss is accompanied by FKHR relocalization to the cytoplasm, by IGFI-R receptor activation, and be deregulation of the cyclin-dependent kinase inhibitor p27.