Surgical Studies on the Role on Gastrin-releasing Peptide in Neuroblastoma

 描述（由申请人提供）：神经母细胞瘤（NB）仍然是最难治疗的儿科癌症之一，因为近三分之二的患者在诊断时存在转移。尽管有积极的治疗方案，“高风险”NB，年龄超过18个月的儿童中的4期肿瘤和/或MYCN扩增，总生存率仅为50%。在对肿瘤难治性和疾病复发的肿瘤生物学的全面理解方面存在显著的差距，因此，阐明负责侵袭性肿瘤行为的信号传导机制对于开发新的靶向临床治疗具有重要意义。G蛋白偶联受体（GPCR）超家族的成员代表了药物开发活动的中心，占所有靶向治疗的40%。我们的实验室先前已经表明，靶向一个这样的GPCR，胃泌素释放肽受体（GRP-R）及其配体GRP抑制NB致瘤性通过调节磷脂酰肌醇3-激酶（PI 3 K）/AKT途径，一个关键的细胞存活途径。在上一个资助期（见进展报告），我们报告了GRP-R信号传导调节NB转移，特别是通过激活AKT 2和下调AKT的内源性负调节因子PTEN。GRP-R信号传导和特定AKT亚型AKT 2在NB从组织侵袭到远处器官转移的多步骤进展中的确切作用尚未阐明。靶向PI 3 K/AKT 2以及AKT轴下游的mTOR可能是一种潜在的策略，因为该途径调节肿瘤血管系统和微环境（TME）。在这项竞争性更新申请中，我们计划确定GRP-R/AKT 2轴调节转移起始细胞的形成和维持及其向远处器官的传播并促进转移性病变建立的确切机制。因此，该提议的中心假设是，经由AKT 2的GRP/GRP-R信号传导调节对常规疗法的抗性和转移灶的形成，从而暗示该轴在NB难治性和疾病复发中的关键作用。为了检验这一假设，我们提出了以下三个具体目的：1）确定GRP-R/AKT 2信号传导在诱导对常规疗法的抗性和肿瘤进展中的作用。2)确定AKT 2在难治性和/或转移性NB中介导GRP/GRP-R致癌作用的作用。3)确定靶向GRP-R/AKT 2在难治性和/或转移性NB中的临床前疗效。我们的目标的成功完成将产生关于GRP/GRP-R介导的NB难治性和疾病复发的机制的重要新知识，包括癌症干细胞在转移中的作用以及肿瘤细胞的外渗及其与TME的相互作用。提出的目标具有直接的翻译相关性，因为它们解决了对常规疗法和TME的耐药性的重要分子机制。最后，临床前研究将进一步提供关于 新疗法对毒性“高风险”NB的安全性和有效性。

 DESCRIPTION (provided by applicant): Neuroblastoma (NB) remains one of the most difficult pediatric cancers to treat, as nearly two-thirds of the patients present with metastasis at the tim of diagnosis. Despite aggressive treatment protocols, `high-risk' NB, stage 4 tumors in children older than 18 months of age and/or MYCN amplification, have dismal overall survival of only 50%. There is a significant gap in the comprehensive understanding of the tumor biology for tumor refractoriness and disease relapse, and therefore, elucidation of signaling mechanisms responsible for the aggressive tumor behavior would be highly significant for development of novel targeted clinical therapies. Members of the G-protein coupled receptor (GPCR) superfamily represent the hub of drug development activities and accounts for 40% of all targeted therapies. Our laboratory has previously shown that targeting one such GPCR, gastrin-releasing peptide receptor (GRP-R) and its ligand GRP inhibited NB tumorigenicity via regulation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, a key cell survival pathway. During the previous funding period (see Progress Report), we reported that the GRP-R signaling regulates NB metastasis, specifically through activation of AKT2, and downregulation of PTEN, an endogenous negative regulator of AKT. The exact role of the GRP-R signaling and specific AKT isoform, AKT2, in the multi-step NB progression from tissue invasion to distant organ metastasis is yet to be elucidated. Targeting PI3K/AKT2, as well as mTOR, downstream of AKT, axis may be a potential strategy as this pathway regulates tumor vasculature and microenvironment (TME). In this competitive renewal application, we plan to determine the exact mechanisms by which GRP-R/AKT2 axis regulates the formation and maintenance of metastasis-initiating cells and their dissemination to distant organs and facilitate establishment of metastatic lesions. Hence, the central hypothesis of this proposal is that GRP/GRP-R signaling via AKT2 regulates resistance to conventional therapies and formation of metastatic foci, thereby, implicating a critical role for this axis in NB refractoriness and disease relapse. o examine this hypothesis, we propose the following three Specific Aims: 1) Determine the role of GRP-R/AKT2 signaling in inducing resistance to conventional therapies and tumor progression. 2) Determine the role of AKT2 in mediating the oncogenic effects of GRP/GRP-R in refractory and/or metastatic NB. 3) Determine the preclinical efficacy of targeting GRP-R/AKT2 in refractory and/or metastatic NB. Successful completion of our Aims will yield significant new knowledge regarding the mechanisms of GRP/GRP-R mediated NB refractoriness and disease relapse, including the role of cancer stem cell in metastasis as well as the extravasation of tumor cells and their interactions with TME. The aims proposed have direct translational relevance as they address an important molecular mechanism of resistance to conventional therapies and the TME. Finally, preclinical study will further provide important information on the safety and efficacy of novel therapeutics against virulent `high-risk' NB.