Dissecting and Targeting RB1-Mutant Osteosarcoma

项目摘要/摘要 骨癌是儿童和青少年最常见的原发恶性肿瘤之一。骨肉瘤 几乎占骨肉瘤常见组织学亚型的60%。而五年的存活率 非转移性疾病徘徊在大约70%，转移性疾病，最常见的是肺部转移。 存活率在15%到30%之间。尽管手术和多药化疗取得了进展，但缺乏 对骨肉瘤形成的分子机制的了解阻碍了在 患者在过去40年中的生存情况。骨肉瘤是导致骨肉瘤的主要原因之一。 儿童和青少年的癌症死亡率。因此，对人的功能的阐明 骨肉瘤相关基因(如RB1和P53抑癌基因)探讨其可能的病理机制 骨肉瘤发生、发展和发展的机制对未来的骨肉瘤至关重要 检测和治疗。 诱导多能干细胞(IPSCs)是肿瘤识别的最有前景的平台之一 研究人员。最近，包括我们在内的几个小组成功地将患者来源的ipscs应用于表型癌症。 特征，探索疾病机制，筛选治疗药物。这些发现强烈表明患者- 派生的IPSCs是一种可行的癌症病因学模型和剖析系统。遗传性视网膜母细胞瘤患者 (Rb)，一种遗传性常染色体显性遗传性癌症疾病，由RB1肿瘤的胚系突变/缺失引起 抑癌基因，使骨肉瘤的发病率增加了400倍，这为骨肉瘤提供了一个完善的模型体系 目的：研究RB1在骨肉瘤发生中的作用。 我们的初步研究表明，在Rb IPSC来源的成骨细胞中，剪接体基因增加。 这些结果导致了我们的中心假设，即剪接体功能的改变对于促进肿瘤是重要的 RB1突变型骨肉瘤的发生发展在强劲的初步数据的指导下，我们计划利用RB 患者源性IPSC疾病模型追求三个特定目的阐明其病理机制 参与RB1突变的骨肉瘤：(1)阐明RB1缺失对剪接体上调的影响 基因表达。(2)评价剪接调节剂对骨肉瘤的治疗潜力。(3) 明确CUL9在调节RB1功能中的作用。 总的来说，我们建议的研究将通过表征骨肉瘤领域的特征而广泛影响骨肉瘤领域 剪接体在调节RB1突变骨肉瘤发展中的重要作用。这些研究还将有 发现CUL9肿瘤调控RB1蛋白降解的新分子机制 抑制者。拟议中的实验的成功完成将为广泛的 一系列领域包括癌症遗传学，剪接体基因表达失调，以及泛素- 蛋白酶体蛋白分解途径，每个途径都具有潜在的骨肉瘤治疗的临床应用。

PROJECT SUMMARY/ABSTRACT Bone cancer is one of the most common primary malignancies in children and adolescents. Osteosarcoma comprises almost 60% of the common histological subtypes of bone sarcoma. While the five-year survival rate of non-metastatic disease hovers at approximately 70%, metastatic disease, most often to the lungs, is associated with survival rates of 15% to 30%. Despite advances in surgery and multi-agent chemotherapy, lack of understanding of the molecular mechanisms of osteosarcomagenesis has prevented significant improvement in the survival of patients over the past 40 years. This malignancy makes osteosarcoma one of the leading causes of cancer mortality among children and adolescents. Therefore, elucidation of the function of individual osteosarcoma-associated genes (e.g., RB1 and p53 tumor suppressor genes) to explore the possible pathological mechanisms involved in osteosarcoma initiation, development and progression is critical for future osteosarcoma detection and treatment. Induced pluripotent stem cells (iPSCs) is one of the most promising platforms recognized by cancer researchers. Recently, several groups including us successfully apply patient-derived iPSCs to phenocopy cancer features, explore disease mechanisms, and screen therapeutic drugs. These findings strongly suggest patient- derived iPSCs is a feasible system to model and dissect cancer etiology. Patients with hereditary retinoblastoma (RB), an inherited autosomal dominant cancer disorder caused by germline mutations/deletions in the RB1 tumor suppressor gene, have increased >400 fold incidence of osteosarcoma, which provides a perfect model system to study the role of RB1 in osteosarcomagenesis. Our preliminary studies revealed that an increase of spliceosome genes in RB iPSC-derived osteoblasts. These results lead to our central hypothesis that an altered spliceosome function is important for facilitating tumor initiation and development in RB1-mutant osteosarcoma. Guided by strong preliminary data, we plan to utilize RB patient-derived iPSC disease model to pursue three Specific Aims to elucidate the pathological mechanisms involved in RB1-mutant osteosarcoma: (1) To elucidate how loss of RB1 contributes to upregulated spliceosome gene expression. (2) To evaluate the therapeutic potential of splicing modulators for osteosarcoma treatment. (3) To define the role of CUL9 in regulating RB1 function. Collectively, our proposed research will broadly impact the osteosarcoma field by characterizing the essential role of spliceosome in regulating RB1-mutant osteosarcoma development. These studies will also have potential to uncover novel molecular mechanisms regulating RB1 proteolysis controlled by CUL9 tumor suppressor. Successful completion of the proposed experiment will add valuable and novel insights to a broad range of fields including cancer genetics, dysregulation of spliceosome gene expression, and ubiquitin- proteasome proteolytic pathway, each of which bears potential clinical applications for osteosarcoma treatment.