Optimizing Pro-Apoptotic Therapeutics With Kinase Inhibition in Neuroblastoma

描述（申请人提供）：神经母细胞瘤（Neuroblastoma， NB）是一种常见的儿童实体肿瘤，具有高致死率。大多数患者具有高危特征，由于肿瘤细胞凋亡途径失活，导致化疗耐药。Bcl2同源结构域或BH蛋白（如Bcl2、Mcl1、Bak和Bax）主要通过介导线粒体对激活特异性促死亡BH3蛋白的应激源的反应来控制细胞对化疗的反应。许多肿瘤类型依赖于改变的BH蛋白相互作用来生存。我们的初步数据表明，NB异质表达Mcl1和Bcl2可能通过隔离活性BH3死亡信号来阻止细胞凋亡。此外，在体外和体内，模拟BH3蛋白死亡结构域的BH3模拟肽均能诱导NB细胞凋亡。新的化学修饰稳定肽二级结构，提高血清稳定性和效力。我们建议利用NB中不受调节的凋亡途径的知识来设计合理的促死亡治疗策略，其目的如下：1)确定BH蛋白：在NB中负责异常线粒体凋亡的蛋白相互作用；2)评估化学修饰bh3结构域肽在体外和体内对NB细胞株的功效和效力；3)在这些模型中，当与酪氨酸激酶抑制剂联合靶向神经母细胞瘤中介导存活、增殖和化学反应的受体时，BH3肽的效力得到改善。

DESCRIPTION (provided by applicant): Neuroblastoma (NB) is a common pediatric solid tumor with high lethality. Most patients present with high-risk features and succumb to chemoresistant disease due to disabled tumor apoptosis pathways. Bcl2 homology-domain, or BH, proteins (such as Bcl2, Mcl1, Bak, and Bax) largely govern a cell's response to chemotherapy by mediating mitochondrial reaction to stressors that activate specific pro-death BH3 proteins. Many tumor types depend on altered BH protein interactions for survival. Our preliminary data shows that NB heterogeneously expresses Mcl1 and Bcl2 that may prevent apoptosis by sequestering active BH3 death signals. Further, BH3 mimetic peptides mimicking the death domain of BHS-only proteins potently induce NB apoptosis both in vitro and in vivo. Novel chemical modifications to stabilize peptide secondary structure improve serum stability and potency. We propose to exploit the knowledge of deregulated apoptotic pathways in NB to design rational pro-death therapeutic strategies with the following Aims: 1) Determine BH protein:protein interactions responsible for aberrant mitochondrial apoptosis in NB; 2) Assess the efficacy and potency of chemically modified BH3-domain peptides against NB cell lines both in vitro and in vivo; and 3) Demonstrate improved potency of BH3 peptides in these models when combined with tyrosine kinase inhibitors targeting receptors that mediate survival, proliferation and chemoresponse in neuroblastoma. This proposal lays out a 5-year research and training program that will help the principle investigator transition to become an independent researcher with the ultimate goal of becoming an R01-funded physician-scientist. Her mentors and advisors are leaders in the field of apoptosis, neuroblastoma, and experimental therapeutics. She will take advantage of the ample resources offered through the environments of both the Children's Hospital of Philadelphia and the University of Pennsylvania to foster her career development. Relevance. Neuroblastoma is a highly lethal tumor with no curative therapy following relapse. Current treatments are ineffective and new treatment depends on the identification of therapies that target tumor-specific biology. BH3 peptides that potently kill NB and other cancer cells prove promising as translational pro-death therapeutics given recent novel chemical modifications to improve peptide structure. Combining BH3 peptides with clinically available kinase inhibitors demonstrates that targeting both survival signaling and apoptosis using rationally chosen agents will provide a novel and effective approach to treating cancers resistant to current conventional treatment modalities.