Design of Therapeutic Peptide-Based Nanoparticles

描述(由申请人提供)：随着对制药行业投资的增加，市场上新药的数量出现了矛盾的下降。造成这一现象的原因之一是制药公司将重点放在小分子药物的开发上。尽管它们是靶蛋白的有效抑制剂，但小分子以其低特异性而闻名。更大和更复杂的分子，如多肽，提供更具体的目标识别。然而，多肽是不稳定的，需要设计细胞递送机制。利用多肽分子在生物溶剂中的结构可塑性是解决多肽类药物问题的新途径。在水溶液中，某些多肽表现出独特的β-发夹构象，使它们能够组装成球形纳米结构。纳米结构遇到质膜的疏水环境，分解，插入膜中，改变其构象，抑制靶蛋白。我推测，通过研究多肽组装成纳米颗粒的机制，有可能制定出一套设计能够形成纳米颗粒的多肽的要求。长期目标是定义多肽之间分子间相互作用的要求，以便组装成纳米颗粒。了解多肽结构转变的机制将有助于开发能够执行一系列编码任务的新型治疗纳米粒。我将通过研究单体多肽的结构、纳米颗粒组装的机制以及脂质环境中的结构变化来解决此类多肽设计的要求。我提出了以下具体目标：(1)利用核磁共振技术确定能够组装成纳米颗粒的单体多肽的结构要求；(2)使用核磁共振、电子显微镜和动态光散射技术确定负责将多肽组装成纳米颗粒的分子间相互作用；(3)通过核磁共振分析多肽分子在脂质环境中经历的结构变化。 公共卫生相关性：本申请旨在阐明多肽组装成球形纳米颗粒的机制，并基于结构优化趋化因子受体CXCR4抑制物肽F22的抗癌活性。聚乙二醇化的F22多肽在小鼠乳腺癌消退模型中组装成球形纳米颗粒，抑制乳腺癌生长，延长生存期。F22自组装到纳米粒中可以防止多肽在血流中降解，并由于增强的通透性和滞留效应而提供F22到表达CXCR4的肿瘤的靶向递送。作为拟议研究的结果，所获得的知识可应用于新型多肽药物的开发。

DESCRIPTION (provided by applicant): With increasing investment into pharmaceutical industry there is a paradoxical decline in the number of new medicines on the market. One of the reasons for this phenomenon is the focus of pharmaceutical companies on small molecules for development of therapeutic agents. Although they are potent inhibitors of target proteins, small molecules are known for their low specificity. Larger and more complex molecules, such as peptides, provide more specific target recognition. However, peptides are unstable and require design of cellular delivery mechanisms. Utilization of structural plasticity of peptide molecules in biological solvents is a novel approach to solve the problems with peptide pharmaceutical agents. In aqueous solutions certain peptides exhibit a distinct beta-hairpin conformation that allows them to assemble into spherical nanostructures. Nanostructures encounter a hydrophobic environment of the plasma membrane, disassemble, insert into the membrane, change their conformation, and inhibit target proteins. I hypothesize that by studying the peptide assembly mechanism into nanoparticles it is possible to formulate a set of requirements for the design of peptides capable to form nanoparticles. The long term goal is to define the requirements for intermolecular interactions between peptides allowing assembly into nanoparticles. Understanding the mechanism of peptide structure transitions will enable development of novel therapeutic nanoparticles capable of performing an encoded sequence of tasks. I shall address the requirements for the design of such peptides by studying the structure of the monomeric peptides, the mechanism of nanoparticle assembly, and the structural changes in the lipid environment. I propose the following specific aims: (1) Determine the structural requirements for the monomeric peptide that allow assembly into nanoparticles using nuclear magnetic resonance (NMR) techniques; (2) Identify the intermolecular interactions responsible for peptide assembly into nanoparticles using NMR, electron microscopy, and dynamic light-scattering; (3) Analyze structural changes that the peptide molecules undergo in the lipid environment by NMR. PUBLIC HEALTH RELEVANCE: This application addresses elucidation of mechanisms of peptide assembly into spherical nanoparticles and structure-based optimization of anti-cancer activity of chemokine receptor CXCR4 inhibitor peptide f22. PEGylated f22 peptide assembles into spherical nanoparticles, inhibits breast cancer growth, and prolongs survival in mouse breast cancer dissipation model. F22 self-assembly into nanoparticles may prevent peptide degradation in the blood stream and provide targeted delivery of f22 to CXCR4 expressing tumors due to the enhanced permeability and retention effect. The knowledge acquired as a result of the proposed research may be applied to the development of novel peptide pharmaceutical agents.