Using mouse models to understand retinoblastoma initiation and progression

描述（由申请人提供）：视网膜母细胞瘤是一种恶性儿科肿瘤，绝大多数病例发生RB基因突变。虽然视网膜母细胞瘤是由RB失活启动的，但RB丢失和肿瘤发生之间的步骤还不清楚。本研究旨在探讨视网膜母细胞瘤发生和发展为恶性肿瘤的变化。视网膜母细胞瘤中与RB缺失合作的机制可能与许多人类癌症广泛相关。我推测，继发性改变帮助视网膜母细胞瘤细胞的起源逃避一个途径，以控制Rb家族成员，p130的细胞周期退出。这些继发性改变可以通过控制细胞周期蛋白依赖性激酶（CDK）来改变p130的活性，或者可以在途径中的其他点起作用（例如通过调节E2 F转录因子）。此外，我推测，逃避p130控制的细胞周期退出RB缺陷的细胞可能是重要的，不仅为视网膜母细胞瘤，但对其他肿瘤类型。为了验证这些假设，我们将使用小鼠遗传学，细胞培养研究和原发性人类和小鼠肿瘤样本的调查相结合。这些研究将利用小鼠模型的力量来确定候选Rb合作基因是否对肿瘤发生重要，并了解这些合作基因如何与Rb丢失协同作用。具体目的1：探讨Arf在视网膜母细胞瘤中作为抑癌基因的作用机制。具体目标2：评估N-myc是否改变pRB家族成员在促进肿瘤发生中的活性。这项工作对于理解许多表现出RB通路失活的人类肿瘤类型具有重要意义。如果RB家族成员控制的通路通过继发性改变而功能失活，则这些通路的重新激活可能为治疗干预提供新的机会。

DESCRIPTION (provided by applicant): Retinoblastoma is a malignant pediatric tumor in which mutations in the RB gene occur in the vast majority of cases. While retinoblastoma is initiated by RB inactivation, the steps between RB loss and tumorigenesis are not well understood. This proposal aims to investigate the changes that occur as retinoblastomas initiate and progress to malignancy. Mechanisms of cooperation with RB deletion in retinoblastoma may be broadly relevant for many human cancers. I hypothesize that secondary alterations help the retinoblastoma cell of origin evade a pathway to cell cycle exit controlled by the Rb family member, p130. These secondary alterations may alter the activity of p130 through control of cyclin dependent kinases (CDKs) or may act at other points in the pathway (e.g. by regulating E2F transcription factors). Moreover, I hypothesize that evasion of p130-controlled cell cycle exit in RB-deficient cells may be important not only for retinoblastoma, but for other tumor types. To test these hypotheses, we will use a combination of mouse genetics, cell culture studies and investigation of primary human and murine tumor samples. These studies will use the power of mouse models to determine definitively whether candidate Rb-cooperating genes are important for tumorigenesis and to understand how these co-operating genes synergize with Rb loss. Specific Aim 1: Investigate the mechanism by which Arf functions as tumor suppressor gene in retinoblastoma. Specific Aim 2: Assess whether N-myc alters the activity of the pRB family members in promoting tumorigenesis. This work has important implications for understanding many human tumor types that exhibit RB pathway inactivation. If pathways controlled by RB family members are functionally inactivated through secondary alterations, then reactivation of such pathways may provide new opportunities for therapeutic intervention.