Evaluating ADGRB3 as a tumor suppressor epigenetically silenced in WNT medulloblastoma

项目总结：与首次提交相比无变更 目前迫切需要为髓母细胞瘤（MB）患者开发新的治疗方法， 儿童中枢神经系统恶性肿瘤目前的治疗方法包括手术、放疗、 和化疗，根据亚型，5年生存率为40-90%。但儿童 因治疗而导致严重的疾病，包括神经、智力和身体残疾。 本项目的总体目的是研究ADGRB 3受体在易感性中的作用。 探讨小脑转化的相关机制，并探索MB的新治疗方法。ADGRB3 是一种在脑中特异性表达的孤儿七跨膜G蛋白偶联受体（GPCR）， 属于粘附型亚家族。我们的新的初步数据表明，ADGRB 3表达是 在WNT组的MB患者中显著降低，并且启动子在表观遗传学上沉默， 这表明ADGRB 3损失可能促进WNT-MB形成。我们提供证据证明 甲基化的CpG结合蛋白MBD 2和组蛋白甲基转移酶EZH 2的表达， 染色质此外，我们发现ADGRB 3的再活化可以减少细胞增殖和肿瘤生长， 支持肿瘤抑制作用。为了在生理环境中测试这一点，我们产生了ADGRB 3敲除。 (KO)小鼠，我们计划将其与在神经祖细胞中表达突变型b-连环蛋白的小鼠杂交， 菱形唇和背侧脑干，它们是WNT-MB的起源细胞。基于这些结果，我们 假设ADGRB 3是小脑中肿瘤抑制因子， 表观遗传学疗法可能代表了WNT-MB儿童的一种新的治疗干预。来测试我们 假设，我们提出了以下目标：（i）识别和靶向表观遗传机制（S）的基础 WNT-MB中ADGRB 3基因沉默，（ii）确定ADGRB 3表达是否恢复以及如何恢复 可以抑制MB细胞生长、致癌信号传导和致瘤特性，和（iii）确定是否丧失 在致癌性Ctnnb 1激活背景下ADGRB 3基因表达的降低使小鼠易患小脑 转化和MB肿瘤发展。这些研究很重要，因为它们增加了我们的知识 关于中枢神经系统的发育神经生物学，并可能导致新的治疗方法的发展， 髓母细胞瘤患者的手术方法。

PROJECT SUMMARY: No changes from initial submission There is an urgent need to develop novel therapies for patients with medulloblastoma (MB), the most common malignant central nervous system (CNS) tumor in children. Current treatments include surgery, radiotherapy, and chemotherapy and result in 5-year survival rates of 40-90% depending on subtype. However, children suffer important morbidity secondary to treatment, including neurological, intellectual and physical disabilities. The overall purpose of the present project is to investigate the role of the ADGRB3 receptor in susceptibility of cerebellar transformation, and explore new therapies for MB based on the related mechanisms. ADGRB3 is an orphan seven transmembrane G protein-coupled receptor (GPCR) specifically expressed in the brain, and belonging to the adhesion-type sub-family. Our new preliminary data show that ADGRB3 expression is significantly reduced in patients with MBs of the WNT group, and the promoter is epigenetically silenced, suggesting that ADGRB3 loss may facilitate WNT-MB formation. We present evidence for the involvement of methylated CpG binding protein MBD2 and histone methyltransferase EZH2 in switch to a silent chromatin. Moreover, we show that reactivation of ADGRB3 can reduce cell proliferation and tumor growth, supporting a tumor suppressive role. To test this in the physiological setting, we generated ADGRB3 knockout (KO) mice, which we plan to cross with mice expressing mutant b-catenin in neural progenitors of the rhombic lip and dorsal brainstem, which are the cells of origin of WNT-MB. Based on these results, we hypothesize that ADGRB3 is a tumor suppressor in the cerebellum and that restoration of its expression with epigenetic therapy may represent a novel therapeutic intervention for children with WNT-MB. To test our hypothesis, we propose the following aims: (i) identify and target the epigenetic mechanism(s) underlying ADGRB3 gene silencing in WNT-MB, (ii) determine whether and how restoration of ADGRB3 expression can inhibit MB cell growth, oncogenic signaling and tumorigenic properties, and (iii) determine whether loss of ADGRB3 gene expression in the background of oncogenic Ctnnb1 activation predisposes mice to cerebellar transformation and MB tumor development. These studies are important as they increase our knowledge about developmental neurobiology in the CNS, and may lead to the development of novel therapeutic approaches for patients with medulloblastoma.