Characterization of MYCN effects in retinoblastoma progression and targeting MYCN for personalized retinoblastoma treatment (MYtargetRB)

视网膜母细胞瘤是儿童最常见的眼部肿瘤。它是由肿瘤抑制基因RB 1的双等位基因失活引发的肿瘤的范例。额外的遗传改变是罕见的，但转录因子MYCN的扩增是常见的，MYCN mRNA表达超过了在其他肿瘤实体中观察到的水平。解决MYCN失调被认为是一种有前途的治疗方法。在MYtargetRB中，我们假设对视网膜母细胞瘤中MYCN调节的功能后果和分子机制的更完整理解将定义可能受益于MYCN定向治疗的患者目标群体。我们的实验方法包括使用MYCN定向的shRNA在视网膜母细胞瘤细胞系中遗传靶向MYCN表达，以表征MYCN对体外和卵内试验中增殖、凋亡、细胞周期、肿瘤细胞侵袭力和转移潜力的影响。MYtargetRB的第二部分致力于研究MYCN作为视网膜母细胞瘤创新靶向治疗候选药物的潜力。初步结果显示了令人鼓舞的抗肿瘤作用，靶向MYCN的表观遗传调节或MYCN蛋白的稳定性。将在体外和卵内视网膜母细胞瘤模型中评估靶向MYCN的几种小分子的作用，并将用RNA-Seq定量对下游靶标的基因表达的作用。基于基因表达谱中的特征，我们将MYCN签名定义为能够选择对MYCN定向治疗反应最佳的分子肿瘤亚组的预测性生物标志物。然后，该特征用于对12种原发性视网膜母细胞瘤进行分类，并定义每个亚组的临床参数。该项目的主要目标是描述MYCN在视网膜母细胞瘤肿瘤发生中的作用，并为MYCN靶向视网膜母细胞瘤的治疗潜力提供第一批数据。需要一种新的治疗药物来提高预后不良的转移性视网膜母细胞瘤患者的生存率，并减少幸存者的长期后遗症。

Retinoblastoma is the most common eye tumor in childhood. It is the paradigm of a tumor that is initiated by biallelic inactivation of the tumor suppressor gene RB1. Additional genetic alterations are rare, but amplification of the transcription factor MYCN is common and MYCN mRNA expression exceeds levels observed in other tumor entities. Addressing MYCN deregulation is considered a promising therapeutic approach across entities. In MYtargetRB, we hypothesize that a more complete understanding of the functional consequences and molecular mechanisms of MYCN modulation in retinoblastoma will define a patient target group who may benefit from MYCN-directed therapies. Our experimental approaches include genetic targeting of MYCN expression in retinoblastoma cell lines using MYCN-directed shRNA to characterize the effect of MYCN on proliferation, apoptosis, cell cycle, tumor cell invasiveness and metastatic potential in vitro and in in ovo assays. The second part of MYtargetRB is dedicated to investigate the potential of MYCN as a candidate for innovative targeted therapies of retinoblastoma. Preliminary results show an encouraging anti-tumor effect targeting either epigenetic regulation of MYCN or the stability of MYCN protein. The effect of several small molecules targeting MYCN will be assessed in in vitro and in ovo retinoblastoma models and the effect on gene expression of downstream targets will be quantified with RNA-Seq. Based on the characteristics in gene expression profiles, we will define a MYCN signature as a predictive biomarker capable of selecting the molecular tumor subgroup that best responds to MYCN directed therapies. This signature serves to then classify twelve primary retinoblastomas and to define the clinical parameters of each subgroup. The main goal of this project is to characterize the role of MYCN in retinoblastoma tumorigenesis and to provide first data for the therapeutic potential of MYCN targeting in retinoblastoma. A new therapeutic agent is needed to improve survival rates in patients with the devastating prognosis of metastasized retinoblastoma and to reduce long-term sequelae in survivors.