Drosophila models of Ret fusions in Papillary Thyroid Carcinoma

描述（由申请人提供）：甲状腺癌的发病率在过去几十年中增加了两倍，使其成为增长最快的癌症形式。80%的甲状腺癌病例是甲状腺乳头状癌（PTC），它是由甲状腺滤泡细胞转化引起的。转移性PTC没有有效的治疗方法，五年生存率为50%，每年在美国导致约1500名患者死亡。5-30%的PTC病例涉及融合蛋白，其中Ret受体酪氨酸激酶与各种胞质蛋白的卷曲螺旋结构域融合。最近，Ret融合也已被确定在肺腺癌的子集。因此，用于Ret融合驱动的肿瘤的治疗剂仍然是未满足的需求。两种Ret融合，CCDC 6-RET（PTC 1）和NcoA 4-RET（PTC 3）占PTC中发现的融合的90%以上。尽管两种融合蛋白都导致Ret的活化，但这两种融合与不同的PTC亚型相关。CCDC 6-RET与典型变异密切相关，这是一种更良性的亚型，而NcoA 4-RET与更具侵袭性和恶性的实体亚型密切相关。Cagan实验室的工作已经验证了与甲状腺髓样癌（MTC）相关的致癌Ret亚型的果蝇模型。这些模型用于探索功能以及识别先导治疗命中。该提案的目的是表征由Ret融合CCDC 6-RET和NcoA 4-RET激活的信号通路，确定具有临床意义的差异，并开发优化的治疗方法。首先，将通过Western印迹分析和免疫荧光来表征和比较果蝇中由CCDC 6-RET和NcoA 4-RET表达引起的信号变化。第二，将临床相关激酶抑制剂喂食表达 Ret融合以鉴定基于转基因诱导的表型的拯救的潜在疗法。最后，PTC肿瘤的遗传复杂性与治疗的相关性将使用预先存在的果蝇激酶组RNAi文库，使用功能驱动者与乘客筛选进行评估。将在哺乳动物模型（如癌细胞系）中评估所有确定的疗法，以确保研究结果与患者相关。本文提出的创新研究将为Ret融合如何驱动PTC，不同的Ret融合在其效果上如何不同以及Ret融合驱动的肿瘤如何对靶向治疗作出反应提供重要见解。

DESCRIPTION (provided by applicant): Rates of thyroid cancer have tripled in the last few decades, making it the fastest growing form of cancer. 80% of thyroid cancer cases are Papillary Thyroid Carcinoma (PTC), which arises from transformation of follicular cells in the thyroid. Metastatic PTC has no effective treatment, a five-year survival rate of 50%, and results in the death of approximately 1500 patients in the US each year. 5-30% of PTC cases involve fusion proteins in which the Ret receptor tyrosine kinase is fused to the coiled-coiled domain of various cytoplasmic proteins. Recently, Ret fusions have also been identified in a subset of lung adenocarcinomas. Thus, therapeutics for Ret fusion-driven tumors remains an unmet need. Two Ret fusions, CCDC6-RET (PTC1) and NcoA4-RET (PTC3) account for greater than 90% of fusions found in PTC. Although both fusion proteins lead to activation of Ret, the two fusions are associated with different PTC subtypes. CCDC6-RET is closely associated with the classic variant, a more benign subtype, and NcoA4-RET is closely associated with the solid subtype, which is more aggressive and malignant. Work by the Cagan lab has validated Drosophila models of oncogenic Ret isoforms that are associated with Medullary Thyroid Carcinoma (MTC). These models were used to explore function as well as identify lead therapeutic hits. The aim of this proposal is to characterize the signaling pathways activated by Ret fusions CCDC6-RET and NcoA4-RET, identify differences that are clinically significant, and develop an optimized therapy. First, signaling changes caused by expression of CCDC6-RET and NcoA4-RET in Drosophila will be characterized and compared by Western blot analysis and immunoflourescence. Secondly, clinically relevant kinase inhibitors will be fed to flies expressing either Ret fusion to identify potential therapies based on rescue of transgene-induced phenotypes. Lastly, the relevance of genetic complexity of PTC tumors on treatment will be evaluated using a functional driver vs. passenger screen using a pre-existing Drosophila kinome RNAi library. All identified therapies will be evaluated in mammalian models, such as cancer cell lines, to ensure the findings are relevant to patients. The innovative studies proposed here will provide critical insight into how Ret fusions drive PTC, how different Ret fusions may differ in their effects, and how Ret fusion driven tumors may respond to targeted therapies.