Using mouse models to understand retinoblastoma initiation and progression

描述(申请人提供)：视网膜母细胞瘤是一种恶性的儿科肿瘤，其中Rb基因突变发生在绝大多数病例中。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尚不清楚。这项建议旨在研究视网膜母细胞瘤开始和进展为恶性时所发生的变化。视网膜母细胞瘤中Rb缺失的协同机制可能与许多人类癌症广泛相关。我推测，继发性改变帮助起源于视网膜母细胞瘤的细胞避开了由Rb家族成员p130控制的细胞周期退出途径。这些继发性改变可能通过控制细胞周期蛋白依赖性蛋白激酶(CDK)来改变p130的活性，也可能作用于该途径的其他点(例如，通过调节E2F转录因子)。此外，我假设在Rb缺陷细胞中逃避p130控制的细胞周期退出可能不仅对视网膜母细胞瘤很重要，而且对其他类型的肿瘤也很重要。为了验证这些假设，我们将结合使用小鼠遗传学、细胞培养研究以及对人类和小鼠原发肿瘤样本的调查。这些研究将利用小鼠模型的力量来明确确定候选Rb协同基因是否对肿瘤发生重要，并了解这些协同基因如何与Rb缺失协同作用。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是否改变了pRb家族成员促进肿瘤发生的活性。这项工作对于理解许多表现出RB途径失活的人类肿瘤类型具有重要的意义。如果RB家族成员控制的通路通过二次改变而在功能上失活，那么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.