Blockade of p53 and Aurora A in Therapy Resistant Neuroblastoma

描述（申请人提供）：神经母细胞瘤是一种起源于神经嵴的肿瘤，是儿童最常见的颅外实体瘤。MYCN扩增，MYC家族个体发生，发生在约25%的神经母细胞瘤，标志着高风险疾病。神经母细胞瘤在实体肿瘤中是独特的，因为所有患者通常对初始化疗有反应。因此，风险与复发有关，复发通常是耐药的。导致这种耐药性的很大一部分复发肿瘤有治疗诱导的p53通路基因突变，在最初表现时并不明显。与人类疾病类似，TH-MYCN神经母细胞瘤小鼠模型对化疗有反应。为了提供化疗耐药、复发性疾病的小鼠模型，我们将TH-MYCN小鼠与p53ER敲入的小鼠杂交，这些小鼠在基线时p53缺乏。暴露于羟他莫昔芬可以快速和可逆的恢复p53。由此产生的神经母细胞瘤肿瘤在基线时显示出增加的外显率和减少的潜伏期。当p53基因恢复后，小鼠最初表现出生存改善，随后复发。在Aim 1中，我将描述肿瘤如何逃避p53的再激活以使。然后，我将描述p53对现有常规和靶向治疗的化疗耐药性的重要性，为新型治疗药物的临床前开发建立基线，包括在Aim 2中产生的药物。MYCN蛋白在神经母细胞瘤中的稳定性受到上游信号通过PI3K/mTOR途径以及Aurora a蛋白的激酶独立支架功能的严格调节。在Aim 2中，我将描述一类新的Aurora a激酶II型抑制剂，这些抑制剂专门设计用于改变Aurora a的二级结构并破坏MYCN的激酶独立稳定性。在初步研究中，我已经确定了候选抑制剂，它们可以显著降低神经母细胞瘤细胞中的MYCN蛋白，并且似乎是通过所提出的不稳定机制来实现的。我将完成构效关系研究，进一步完善这些候选化合物。该研究的成功完成将会改善耐药神经母细胞瘤的模型，以及一种新的靶向Aurora a抑制剂，预计对神经母细胞瘤具有高效力和特异性。

DESCRIPTION (provided by applicant): Neuroblastoma, a tumor of neural crest origin, is the most common extra-cranial solid tumor of childhood. Amplification of MYCN, a MYC family ontogeny, occurs in ~25% of neuroblastoma and marks high-risk disease. Neuroblastoma is unique among solid tumors in that all patients typically respond to initial chemotherapy. Risk is thus associated with relapse, which is typically therapy-resistant. Contributing to this resistance a large proportion of relapsed tumors have therapy-induced mutations in p53 pathway genes, not evident at initial presentation. Mirroring human disease, the TH-MYCN mouse model of neuroblastoma is responsive to chemotherapy. In order to provide a mouse model of chemotherapy resistant, relapsed disease, we have crossed TH-MYCN mice to mice knocked-in for p53ER, which are p53 deficient at baseline. Exposure to hydroxytamoxifen allows rapid and reversible p53 restoration. Resulting neuroblastoma tumors show increased penetrance and decreased latency at baseline. When p53 is restored, mice show initially improved survival followed by relapse. In Aim 1, I will characterize how tumors evade reactivation of p53 to enable. I will then characterize the importance of p53 in chemotherapy resistance to existent conventional and targeted therapies, establishing a baseline for pre-clinical development of novel therapeutic agents, including those generated in Aim 2. The stability of MYCN protein in neuroblastoma is tightly regulated by upstream signaling through the PI3K/mTOR pathway as well as by a kinase-independent scaffolding function of the Aurora A protein. In Aim 2, I will characterize a novel class of Type II inhibitors of Aurora A kinase designed specifically to alter the secondary structure of Aurora A and disrupt the kinase-independent stabilization of MYCN. In pilot studies I have identified candidate inhibitors that dramatically decrease MYCN protein in neuroblastoma cells and that appear to do so by the destabilization mechanism proposed. I will complete structure activity relationship studies to further refine these candidate compounds. Successful completion will result in both an improved model of chemo-resistant neuroblastoma as well as a new class of targeted Aurora A inhibitors, predicted to be both highly potent and specific against neuroblastoma.