RAl GTPases and partners in human bladder cancer metastasis

摘要 膀胱癌每年导致12，000名美国人死亡，但很少有研究项目针对这种疾病。为 大部分病人的死因是癌细胞转移，通常是转移至肺部。因此，我们认为， 更全面地了解推动膀胱癌扩散和生长的分子机制， 肺可能提供新的治疗机会。Ras家族小GTP酶RalA和RalB 已显示在人类肿瘤形成和发展中起重要作用。具体而言，RalB是 在膀胱癌中升高并促进迁移和转移。RalB依赖性的全基因组分析 基因表达的变化显示RalB调节CD24，一种GPI连接的糖蛋白， 这是许多人类癌细胞系生长所必需的。CD24也是膀胱癌转移的生物标志物 癌RalB诱导CD24表达涉及Ral效应子RalBP 1，其在膀胱癌中也升高。 癌症和锌指转录因子RREB1。我们的指导假设是，一部新的RalB？ 本项目发现的RalBP 1 <$RREB 1 <$CD 24信号通路促进膀胱癌 转移为了验证这一假设，我们提出了以下具体目标：在目标1中， RalB和RalBP1对膀胱癌肺转移的贡献将使用RalB和RalBP1的突变体进行剖析。 在特定功能和效应物相互作用中受损。由于RalA不促进移民， 转移，我们将使用RalA/RalB嵌合体来鉴定转移所必需的RalB序列， 随后通过这些区域与RalB特异性结合的蛋白质。成功实现这一目标， 为药物发现提供新的靶点。目的2将确定RalB和RalBP 1如何调节RREB 1活性 并评估CD24表达中对RREB1调节的需求。由于RalB的全基因组分析 依赖性基因表达导致转移生物标志物CD24的发现，我们将使用人 膀胱癌组织库和先进的计算工具，以生成RalB的基因签名 表情考虑到RalB在膀胱癌进展中的重要性， 将评估患者中转移性疾病的发展。最终，这个签名可能是 预后价值和选择患者进行个体化RalB靶向治疗的途径。在目标3中， 评估膀胱癌转移对CD24的需求。现有的CD24敲除小鼠将被 用于研究CD24在膀胱癌形成、侵袭和转移的化学致癌模型中的作用。 转移在一项临床前研究中，我们还将测试抗CD24免疫疗法是否可以阻断肿瘤细胞的生长。 已证实的人膀胱癌肺转移。这些关于一种新的信号通路的机制研究 将提供Ral GTP酶如何促进膀胱癌肺转移的分子信息， 为未来的患者风险分层提供了框架，并为新的治疗方法提供了机会， 转移性疾病项目叙述 膀胱癌每年导致12，000名美国人死亡，但很少有研究项目针对这种疾病。为 大部分病人的死因是癌细胞转移，通常是转移至肺部。目标 该项目的目的是了解人类膀胱癌肺转移的机制， 这些知识来预测和治疗患者的这种情况。

ABSTRACT Bladder cancer kills 12,000 Americans each year, but few research projects are targeted to this disease. For most of these patients, the cause of death is attributable to metastatic spread, commonly to the lungs. Hence, a fuller understanding of the molecular mechanisms driving the dissemination and growth of bladder cancer to the lungs is likely to present new therapeutic opportunities. The Ras family small GTPases RalA and RalB have been shown to play important roles in human tumor formation and progression. Specifically, RalB is elevated in bladder cancer and promotes migration and metastasis. Genome-wide analysis of RalB dependent changes in gene expression revealed that RalB regulates the expression of CD24, a GPI-linked glycoprotein, necessary for the growth of many human cancer cell lines. CD24 is also a biomarker of metastasis in bladder cancer. RalB induction of CD24 expression involves the Ral effector RalBP1, which is also elevated in bladder cancer, and the zinc finger transcription factor RREB1. Our Guiding Hypothesis is that a novel RalB ¿ RalBP1 ¿ RREB1 ¿ CD24 signaling pathway that was discovered by this project, promotes bladder cancer metastasis. To test this hypothesis we propose the following Specific Aims: In Aim 1, the mechanistic contributions of RalB and RalBP1 to bladder cancer lung metastasis will be dissected using mutants of both that are impaired in specific functions and effector interactions. Since RalA does not promote migration or metastasis, we will use RalA/RalB chimeras to identify RalB sequences necessary for metastasis and subsequently proteins that specifically bind to RalB via those regions. Successful completion of this aim should result in new targets for drug discovery. Aim 2 will determine how RalB and RalBP1 regulate RREB1 activity and evaluate the requirement for RREB1 regulation in CD24 expression. Since genome-wide profiling of RalB dependent gene expression led to the discovery of the metastasis biomarker CD24, we will use a human bladder cancer tissue repository and advanced computational tools to generate a gene signature of RalB expression. Given the importance of RalB in bladder cancer progression, the ability of this signature to predict the development of metastatic disease in patients will be evaluated. Eventually, this signature may be of prognostic value and an avenue to select patients for individualized RalB targeted therapy. In Aim 3 we will evaluate the requirement for CD24 in bladder cancer metastasis. An existing CD24 knockout mouse will be used to study the role of CD24 in a chemical carcinogenesis model of bladder cancer formation, invasion, and metastasis. In a preclinical study, we will also test whether anti-CD24 immunotherapy can block the growth of established human bladder cancer lung metastases. These mechanistic studies of a novel signaling pathway will provide molecular information on how Ral GTPases promote bladder cancer lung metastasis, thus providing both a framework for future patient risk stratification and opportunities for novel therapies of metastatic disease. PROJECT NARRATIVE Bladder cancer kills 12,000 Americans each year, but few research projects are targeted to this disease. For most of these patients, the cause of death is attributable to metastatic spread, commonly to the lungs. The goal of this project is to understand the mechanisms that underlie lung metastasis in human bladder cancer and use this knowledge to predict and treat this condition in patients.