Dissecting and Targeting RB1-Mutant Osteosarcoma

项目总结/摘要 骨癌是儿童和青少年最常见的原发性恶性肿瘤之一。骨肉瘤 包括几乎60%的骨肉瘤的常见组织学亚型。虽然五年生存率 非转移性疾病徘徊在约70%，转移性疾病，最常见的是肺部， 存活率在15%到30%之间尽管在手术和多药化疗方面取得了进展， 对骨质疏松症发生的分子机制的理解阻碍了骨发育的显著改善， 过去40年病人的生存率。这种恶性肿瘤使骨肉瘤的主要原因之一， 儿童和青少年的癌症死亡率。因此，阐明个体的功能， 骨肉瘤相关基因（例如，RB 1和p53肿瘤抑制基因），以探讨可能的病理 骨肉瘤发生、发展和进展的机制对未来的骨肉瘤至关重要 检测和治疗。 诱导性多能干细胞（iPSCs）是癌症公认的最有前途的平台之一 研究人员最近，包括我们在内的几个研究小组成功地将患者来源的iPSC应用于表型癌症 特征，探索疾病机制和筛选治疗药物。这些发现有力地表明病人- 衍生的iPSC是建模和剖析癌症病因的可行系统。遗传性视网膜母细胞瘤患者 (RB)，一种由RB 1肿瘤中的生殖系突变/缺失引起的遗传性常染色体显性癌症疾病 抑癌基因，使骨肉瘤的发病率增加了400倍以上，这提供了一个完美的模型系统 研究RB 1在骨肉瘤发生中的作用。 我们的初步研究表明，RB iPSC来源的成骨细胞中剪接体基因的增加。 这些结果导致我们的中心假设，即剪接体功能的改变对于促进肿瘤的发生是重要的。 RB 1突变型骨肉瘤发生和发展。在强有力的初步数据的指导下，我们计划利用RB 患者来源的iPSC疾病模型，以追求三个特定目的来阐明病理机制 RB 1突变型骨肉瘤中的作用：（1）阐明RB 1缺失如何促进剪接体的上调 基因表达。(2)评价剪接调节剂对骨肉瘤的治疗潜力。（三） 目的探讨CUL 9在调节RB 1功能中的作用。 总的来说，我们提出的研究将广泛影响骨肉瘤领域的特点， 剪接体在调节RB 1突变型骨肉瘤发生中的重要作用。这些研究还将 有可能揭示由CUL 9肿瘤控制的调节RB 1蛋白水解的新分子机制 抑制器。成功完成拟议的实验将增加有价值的和新颖的见解， 一系列领域，包括癌症遗传学、剪接体基因表达失调和泛素- 蛋白酶体蛋白水解途径，每一个都具有潜在的临床应用，为骨肉瘤的治疗。

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.