Molecular Biology of Pediatric Tumors

小儿肿瘤的分子生物学

• 批准号: 7331407
• 负责人: LEE J. HELMAN
• 金额: --
• 依托单位: DIVISION OF CLINICAL SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7331407
• 关键词: Molecular; Biology; Pediatric; Tumors

Work on the role of insulin-like growth factors (IGFs) in pediatric sarcomas is continuing to focus on potential therapeutic approaches as well as further defining the downstream signaling events of IGF action. We are currently exploring both humanized moAbs directed against the IGFIR as well as small molecule inhibitors against the IGFIR kinase and are currently analyzing these reagents to determine whether they specifically inhibit metastatic behavior in several mouse models of metastasis in pediatric sarcomas. We ultimately plan to combine this treatment with inhibitors of mTOR. We have continued to study the role of mTOR signaling in pediatric sarcomas. We have linked ezrin expression and metastatic potential (see below) to mTOR activation and have reported that mTOR blockade using rapamysin and its analog, CCI 779, in rhabdomyosarcomas (RMS) and osteosarcomas inhibits both primary tumor growth and metastatic tumor growth and inhibits mTOR signaling in these tumors. We have now demonstrated that mTOR inhibition leads to AKT activation in these models, and that this activation is IGFIR driven, and can be abrogated using a humanized MoAb to the IGFIR. This finding has led to our interest in combining these agents in preclinical and hopefully clinical studies. We have recently demonstrated that one mechanism of growth inhibition by rapamycin appears to be via a HIF1alpha, VEGF inhibitory signal. We have also begun to analyze the potential additive or synergistic effects of combining standard cytotoxic chemotherapy with mTOR inhibition in vitro in RMS cell lines and have seen at least additive effects. We are plan to examine this combination in xenograft models. We have expanded our proteomic analysis of stage III RMS tumor samples from patients treated on COG protocols and expanded analysis continues to suggest that activation of mTOR signaling pathways in these tumor samples is a poor prognostic factor. This data has been presented at ASCO and will hopefully be published shortly. We plan to continue to expand these observations with larger patient numbers. Our work on the role of ezrin in Ewing's sarcomas (ES) has now shown that ezrin is very highly expressed in almost all tumors, and its high expression is associated with activation of anti-apoptotic signaling cascades. We have also demonstrated that blockade of ezrin inhibits metastatic behavior in ES xenografts in a manner analogous to OS models. We have most recently linked ezrin to beta-4 integrin signaling and have shown that blockade of the integrin also leads to inhibition of metastatic behavior in our mouse ostesosarcoma model. We have completed our study the role of chemokine signaling in metastatic behavior of OS, and demonstrated that blocking CXCR5 in OS xenografts blocks metatatic behavior. However, since this effect required pre-incubation with the chemokine antagonist, we have elected to not pursue this line of investigation. We have also begun to attempt to establish an in vitro model of tumor cell-stromal interaction using a mouse OS cell-fibroblast co-culture 3-D system. Preliminary data appears promising and our hope is to use this system to begin to screen for compounds that block this interaction.We have recently begun to a high throughput shRNAi screen in 2 human rhabdomyosarcoma cell lines. We are collaborating with Dr. Lou Staudt who has established this system. We have established the reagents necessary to perform this screen in both an alveolar and an embryonal RMS cell line, and are currently beginning to screen the library to identify genes that are required for tumor cell survival.

关于胰岛素样生长因子（IGF）在小儿肉瘤中的作用的工作一直在继续关注潜在的治疗方法，并进一步定义了IGF作用的下游信号事件。我们目前正在探索针对IGFIR的人性化的摩押，以及针对IGFIR激酶的小分子抑制剂，目前正在分析这些试剂，以确定它们是否在小儿肉瘤中的几种转移小鼠模型中是否明确抑制转移性行为。我们最终计划将这种处理与MTOR的抑制剂结合起来。我们继续研究MTOR信号在小儿肉瘤中的作用。我们已经将Ezrin的表达和转移电位（见下文）与MTOR激活联系起来，并报告说，在横纹肌肉瘤（RMS）和骨肉瘤中，使用Rapamysin及其类似物CCI 779进行了MTOR封锁，而骨肉瘤中的MTOR封锁也抑制了原发性肿瘤的生长，并抑制了MTASPATIC肿瘤的生长，并抑制了MTOR MTOR中的MTOR中的信号。现在，我们已经证明了MTOR抑制作用在这些模型中导致Akt激活，并且这种激活是IGFIR驱动的，并且可以使用人源化的Moab将其驱动到IGFIR上。这一发现使我们有兴趣将这些药物结合在临床前和希望的临床研究中。我们最近证明，雷帕霉素抑制生长的一种机制似乎是通过HIF1Alpha，VEGF抑制信号。我们还开始分析将标准的细胞毒性化疗与MTOR抑制在RMS细胞系中的潜在添加剂或协同作用，并且至少看到了添加剂作用。我们计划在异种移植模型中检查这种组合。我们已经扩展了从COG方案治疗的患者中对III期RMS肿瘤样品的蛋白质组学分析，扩展的分析继续表明，这些肿瘤样品中MTOR信号通路的激活是不良的预后因素。这些数据已在ASCO介绍，希望很快就会发布。我们计划继续以较大的患者人数扩大这些观察结果。我们在Ezrin在Ewing的肉瘤（ES）中的作用的工作现已表明，Ezrin在几乎所有肿瘤中都非常高度表达，并且其高表达与抗凋亡信号传导级联的激活有关。我们还证明，Ezrin的阻断以类似于OS模型的方式抑制ES异种移植物中的转移行为。我们最近将Ezrin连接到β-4整合素信号传导，并表明整联蛋白的阻断还导致抑制我们的小鼠Ostesosarcoma模型中的转移性行为。我们已经完成了研究趋化因子信号在OS转移行为中的作用，并证明OS异种移植物中的CXCR5阻止了Metatatic行为。但是，由于这种作用需要与趋化因子拮抗剂进行预孵育，因此我们选择不进行这一研究。我们还开始尝试使用小鼠OS OS细胞成亲细胞共培养3-D系统建立肿瘤细胞质相互作用的体外模型。初步数据似乎很有希望，我们希望使用该系统开始筛选阻断这种相互作用的化合物。我们最近开始在2种人类横纹肌肉瘤细胞系中进行高吞吐量的Shrnai屏幕。我们正在与建立该系统的Lou Staudt博士合作。我们已经建立了在肺泡和胚胎RMS细胞系中执行此筛选所需的试剂，目前正开始筛选文库以识别肿瘤细胞存活所需的基因。