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) 在儿科肉瘤中的作用的研究继续关注潜在的治疗方法，并进一步定义 IGF 作用的下游信号事件。我们目前正在探索针对 IGFIR 的人源化单克隆抗体以及针对 IGFIR 激酶的小分子抑制剂，并正在分析这些试剂以确定它们是否能特异性抑制几种小儿肉瘤转移小鼠模型的转移行为。我们最终计划将这种治疗与 mTOR 抑制剂结合起来。我们继续研究 mTOR 信号传导在儿科肉瘤中的作用。我们将 ezrin 表达和转移潜力（见下文）与 mTOR 激活联系起来，并报道了在横纹肌肉瘤 (RMS) 和骨肉瘤中使用雷帕霉素及其类似物 CCI 779 阻断 mTOR 可抑制原发性肿瘤生长和转移性肿瘤生长，并抑制 mTOR 信号转导在这些肿瘤中。我们现在已经证明，mTOR 抑制会导致这些模型中的 AKT 激活，并且这种激活是 IGFIR 驱动的，并且可以使用针对 IGFIR 的人源化 MoAb 来消除。这一发现引起了我们在临床前研究和临床研究中结合这些药物的兴趣。我们最近证明，雷帕霉素抑制生长的一种机制似乎是通过 HIF1α、VEGF 抑制信号。我们还开始在 RMS 细胞系中分析标准细胞毒性化疗与体外 mTOR 抑制相结合的潜在相加或协同效应，并且至少看到了相加效应。我们计划在异种移植模型中检查这种组合。我们扩大了对来自接受 COG 方案治疗的患者的 III 期 RMS 肿瘤样本的蛋白质组学分析，扩大的分析继续表明这些肿瘤样本中 mTOR 信号通路的激活是一个不良的预后因素。该数据已在 ASCO 上公布，有望很快发布。我们计划继续扩大这些观察范围，扩大患者数量。我们对埃兹蛋白在尤文氏肉瘤（ES）中作用的研究现已表明，埃兹蛋白在几乎所有肿瘤中都非常高表达，并且其高表达与抗凋亡信号级联的激活有关。我们还证明，埃兹蛋白的阻断以类似于 OS 模型的方式抑制 ES 异种移植物的转移行为。我们最近将埃兹蛋白与β-4整合素信号传导联系起来，并证明整合素的阻断也可以抑制我们的小鼠骨肉瘤模型中的转移行为。我们已经完成了趋化因子信号传导在 OS 转移行为中的作用的研究，并证明阻断 OS 异种移植物中的 CXCR5 可阻断转移行为。然而，由于这种效应需要与趋化因子拮抗剂预先孵育，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 细胞-成纤维细胞共培养 3-D 系统建立肿瘤细胞-基质相互作用的体外模型。初步数据看起来很有希望，我们希望利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通量 shRNAi 筛选。我们正在与 Lou Staudt 博士合作，他建立了这个系统。我们已经建立了在肺泡和胚胎 RMS 细胞系中进行此筛选所需的试剂，并且目前正在开始筛选文库以鉴定肿瘤细胞存活所需的基因。