pHLIP Nanotechnology Platform for Cancer Imaging and Therapy

描述（由申请人提供）：我们的项目是基于水溶性膜肽pHLIP的使用，我们已经通过全身荧光和PET成像显示，pHLIP在体内选择性靶向酸性实体瘤，并将极性货物分子转运到培养的癌细胞的胞浆中。pHLIP在弱酸性条件下作为单体单向插入穿过细胞膜的脂质双层，如在肿瘤中发现的，并形成跨膜α螺旋，而在健康组织的正常细胞外pH下几乎不存在穿过细胞膜的插入。迄今为止，无论是对培养细胞还是对小鼠，均未观察到pHLIP暴露的毒性作用。在这里，我们建议开发一个纳米技术平台的基础上使用的pHLIP-生物纳米注射器的肿瘤的成像和治疗剂的选择性交付。通过将货物分子附着在pHLIP的末端，使其留在膜外，我们可以将成像或治疗探针锚在癌细胞表面，从而促进诊断、治疗和治疗监测。通过经由可切割的连接将货物连接到其插入末端，pHLIP可用于将极性的、细胞不可渗透的分子选择性易位到癌细胞中。通过三个实验室的共同努力，这项有前途的技术将有可能得到广泛的发展。我们将使用pHLIP靶向来测试癌症模型，并确定肿瘤生长和发展如何与肿瘤酸度相关。为了改进pHLIP技术，我们将设计、合成和测试各种树状聚合物-pHLIP构建体，以使多种治疗和/或成像探针能够递送至肿瘤。我们将介绍一种通过可裂解的S-S键将货物分子和荧光染料同时偶联到pHLIP的C-末端的合成方案，并建立pHLIP可以通过膜的脂质双层转位的货物分子的性质（极性，形状，电荷和大小），定义一种新的极性治疗分子，可以用于肿瘤治疗。我们将测试pHLIP的细胞内交付的两个功能性细胞在体内不可渗透的分子：毒素（鬼笔环肽）和基因调控剂（肽核酸）。重要的是，我们将尝试通过标记的pHLIP-鬼笔环肽同时检测和治疗肿瘤，这是我们第一个潜在的抗转移药物。此外，我们将开发用于在体内癌细胞表面特异性拴系和组装纳米颗粒的两步递送方案：1）使用具有结合结构域的pHLIP靶向肿瘤，其将被拴系到癌细胞的表面，以及2）用含有治疗和/或成像有效载荷并具有表面暴露的互补结合结构域的脂质体靶向pHLIP。受当前版本pHLIP特性的启发，我们将进一步评估pHLIP序列变异对肽插入膜的影响，从而设计出具有一系列有用特性的第二代纳米注射器。pHLIP纳米技术为癌症的疾病特异性成像和治疗提供了新的方法。我们的最终目标是改善癌症的诊断和治疗，癌症占美国和其他发达国家所有死亡人数的25%左右。有几个方面的问题，我们的技术发展可能是有用的，但主要的概念是选择性地将治疗和成像剂输送到肿瘤细胞。该技术的另一个方面是，它允许使用一类新的治疗剂：细胞不可渗透的分子，这些分子只会转移到患病组织中的细胞中，而不会影响健康细胞。基于这些概念的治疗将表现出更高的疗效和/或显著减少的副作用。这种改进对于癌症治疗尤其重要，因为大多数抗癌药物都是损害正常细胞的毒药。

DESCRIPTION (provided by applicant): Our project is based on the use of a water-soluble membrane peptide, pHLIP, which we have shown, by whole-body fluorescence and PET imaging, to selectively target acidic solid tumors in vivo and to translocate polar cargo molecules into the cytoplasms of cultured cancer cells. pHLIP inserts unidirectionally across the lipid bilayer of a cell membrane as a monomer under mildly acidic conditions, as are found in tumors and forms a transmembrane alpha helix, whereas there is practically no insertion across the membranes of cells with the normal extracellular pH of healthy tissue. To date, no toxic effects of pHLIP exposure have been observed either for cells in culture or for mice. Here we propose to develop a nanotechnology platform for selective delivery of imaging and therapeutic agents to tumors based on the use of the pHLIP-bionanosyringe. By attaching cargo molecules to the end of pHLIP that stays outside of the membrane, we can anchor imaging or therapeutic probes to the surfaces of cancer cells, facilitating diagnosis, treatment and therapeutic monitoring. By attaching cargo to its inserted end via cleavable links, pHLIP can be used for the selective translocation of polar, cell-impermeable molecules into cancer cells. By combining the efforts of three laboratories, a broad development of this promising technology will be possible. We will use pHLIP targeting to test cancer models and establish how tumor growth and development correlate with tumor acidity. To improve pHLIP technology, we will design, synthesize and test various dendrimeric-pHLIP constructs to enable delivery of multiple therapeutic and/or imaging probes to tumors. We will introduce a synthetic scheme of simultaneous conjugation of cargo molecules and fluorescent dyes to the C-terminus of pHLIP via a cleavable S-S bond and establish the properties (polarity, shape, charge and size) of cargo molecules that pHLIP can translocate through the lipid bilayer of a membrane, defining a new, polar class of therapeutic molecules that can be delivered for tumor treatment. We will test pHLIP for the intracellular delivery of two functional cell-impermeable molecules in vivo: a toxin (phalloidin) and a gene regulation agent (Peptide Nucleic Acid). Importantly, we will attempt the simultaneous detection and treatment of tumors by labeled pHLIP-phalloidin, which is our first lead for a potential antimetastatic drug. Further, we will develop a two-step delivery scheme for the specific tethering and assembly of nanoparticles at the surfaces of cancer cells in vivo: 1) targeting tumors using pHLIP with a binding domain, which will be tethered to the surface of cancer cells and 2) targeting the pHLIP with liposomes containing therapeutic and/or imaging payloads and having a surface-exposed complementary binding domain. Inspired by the properties of pHLIP in its current version, we will further evaluate the effect of pHLIP sequence variation on peptide insertion into a membrane, enabling the design of a second generation of the nanosyringe with a range of useful properties. pHLIP nanotechnology offers a new approach for the disease-specific imaging and treatment of cancers. Our ultimate goal is to improve the diagnosis and treatment of cancer, which is responsible for about 25% of all deaths in the USA and other developed countries. There are several aspects of the problem where our technology development could be useful, but the major concept is the selective delivery of therapeutic and imaging agents to cells in tumors. Another aspect of the technology is that it permits the use of a new class of therapeutic agents: cell-impermeable molecules that would be translocated into cells only in diseased tissue while not affecting healthy cells. A therapy based on these concepts would exhibit much higher efficacy and/or significantly reduced side effects. Such improvements are especially important for cancer treatment, since the majority of anti-cancer drugs are poisons that damage normal cells.