The effects of PTEN on tyrosine kinase signaling in Breast Cancer

项目摘要/摘要 这些研究的目的是了解肿瘤抑制因子磷酸酶和 10号染色体张力蛋白同源缺失(PTEN)在乳腺癌中的表达及PTEN功能在乳腺癌中的作用 酪氨酸激酶信号转导。磷脂酰肌醇-3激酶(PI3K)途径的异常激活是 人类癌症中最常见的分子改变，最常见的原因是表达缺失或功能丧失 PTEN基因突变。PTEN作为PI3K下游的一种脂质磷酸酶来拮抗PI3K信号，但是 PTEN蛋白磷酸酶活性对肿瘤的抑制作用仍未解决。PTEN缺乏症 结果在包括胰岛素样生长因子-I受体(IGF-IR)在内的受体酪氨酸激酶(RTK)的激活中， 胰岛素受体(InsR)和ErbB3/HER3，提示PTEN参与信号的上游和下游调控。 在PI3K下游。因此，我假设1)PTEN蛋白的肿瘤抑制作用 磷酸酶活性涉及包括RTK在内的癌蛋白的直接去磷酸化，以及2)PTEN缺失 使癌细胞对RTK抑制反应敏感。支持假设1的结果表明PTEN的丢失 不仅增加了PI3K途径的信号转导，而且还通过蛋白质介导的方式增加了致癌信号 路径仍有待定义。在这种情况下，抑制PI3K可能不足以阻止肿瘤的生长 PTEN缺陷性肿瘤。支持假设2的结果将PTEN缺失作为患者的生物标记物 可能从RTK指导的治疗中受益的亚群。为了检验这些假设，我提出了以下建议 具体目的：1)确定PTEN缺失是否对IGF-I、胰岛素和HER3受体信号转导有调节作用； 2)确定PTEN丢失是否对IGF-IR、InsR和HER3的治疗抑制剂敏感；3) 发现PTEN的磷酸蛋白底物以及PTEN蛋白磷酸酶活性对 酪氨酸激酶信号转导。PTEN蛋白底物的全谱分析及PTEN缺失对酪氨酸的影响 激酶信号转导将识别PTEN的新角色，提供因PTEN缺失而改变的候选磷酸蛋白，以及 揭示信号通路之间的新联系。胰岛素样生长因子-IR在大多数人的乳房中表达 治疗癌症和治疗性胰岛素样生长因子-IR抑制剂正在开发中。PTEN基因缺失对血管内皮细胞生长的影响 IGF-IR信号和对IGF-IR靶向治疗的敏感性将揭示PTEN的新功能，以及 确定PTEN状态是否为治疗反应的生物标志物。反过来，这些集体发现将 允许针对IGF-IR和PI3K途径的治疗进行优化。在此提出的研究将 在范德比尔特-英格拉姆癌症中心进行，其设施和中心非常适合 这项研究涉及分子、遗传、蛋白质组和活体动物成像分析。这个机构也 提供广泛的教学活动和职业发展机会，以加强对青少年的培训 调查人员。上述研究将为我在一个丰富的环境中提供更好的科学训练 合作和跨学科研究，以促进成长和独立。我近期的职业目标 是获得一个独立的、终身教职的助理教授职位来建立我自己的 实验室和研究团队，长期目标是在 基于机制的转化型癌症研究。

Project Summary/Abstract The objective of these studies is to understand the effects of loss of the tumor suppressor Phosphatase and Tensin homolog deleted on chromosome 10 (PTEN) in breast cancer, and the effects of PTEN functions on tyrosine kinase signaling. Aberrant activation of the phosphatidylinositol-3 kinase (PI3K) pathway is one of the most frequent molecular alterations in human cancer, most often by loss of expression or loss-of-function mutations in PTEN. PTEN acts as a lipid phosphatase downstream of PI3K to antagonize PI3K signaling, but PTEN protein phosphatase activity has tumor suppressive effects which remain unresolved. PTEN deficiency results in activation of receptor tyrosine kinases (RTKs) including insulin-like growth factor-I receptor (IGF-IR), insulin receptor (InsR), and ErbB3/HER3, implicating PTEN in the modulation of signaling both upstream and downstream of PI3K. I therefore hypothesize that 1) the tumor suppressive effects of PTEN protein phosphatase activity involve direct dephosphorylation of oncoproteins including RTKs, and 2) PTEN loss sensitizes cancer cells to RTK inhibition. Results in support of hypothesis #1 would suggest that loss of PTEN not only increases PI3K pathway signaling, but also increases oncogenic signaling through protein-directed pathways that remain to be defined. In this case, PI3K inhibition may be insufficient to block the growth of PTEN-deficient tumors. Results in support of hypothesis #2 would offer PTEN loss as a biomarker of a patient subpopulation likely to benefit from RTK-directed therapy. To test these hypotheses, I propose the following Specific Aims: 1) To determine whether loss of PTEN modulates IGF-I, insulin, and HER3 receptor signaling; 2) To determine whether PTEN loss sensitizes to therapeutic inhibitors of IGF-IR, InsR, and HER3; 3) To discover phosphoprotein substrates of PTEN and the global effects of PTEN protein phosphatase activity on tyrosine kinase signaling. Global profiling of PTEN protein substrates and the effects of PTEN loss on tyrosine kinase signaling will identify novel roles of PTEN, offer candidate phosphoproteins altered by PTEN loss, and reveal new connections between signaling pathways. IGF-IR is expressed in the majority of human breast cancers, and therapeutic IGF-IR inhibitors are being developed. Identification of the effects of PTEN loss on IGF-IR signaling and sensitivity to IGF-IR-targeted therapies will reveal novel functions of PTEN, and determine whether PTEN status is a biomarker of response to therapy. In turn, these collective findings will allow the optimization of therapies targeting the IGF-IR and PI3K pathways. The studies proposed herein will be carried out at the Vanderbilt-Ingram Cancer Center, with facilities and centers ideally suited for the molecular, genetic, proteomic, and live animal imaging analyses involved in this research. This institution also provides extensive didactic activities and career development opportunities to enhance the training of young investigators. The above studies will provide me with enhanced scientific training in an environment rich with collaborations and interdisciplinary research to promote growth and independence. My immediate career goal is the acquisition of an independent, tenure-track, assistant professor faculty position to establish my own laboratory and research team, with the long-term goal of establishing an extramurally-funded program in mechanism-based translational cancer research.