Reductase Enzyme-responsive, Self-immolative Nanovehicles

描述(申请人提供)：本申请的目的是评估一种假设，即由氧化还原反应磷脂制成的囊泡(脂质体)可以通过脂质体与一种在大多数癌症肿瘤组织中高度集中的特定的苯醌还原酶相互作用而有效地释放，即NAD(P)H：苯醌氧化还原酶1型(NQO1，DT-黄递酶)。这一点的证明将使一组史无前例的氧化还原敏感脂质体的未来发展成为可能，这种脂质体在结构上进行了优化，优先在肿瘤中积累，并以特定部位的方式传递其内容物，这是它们因癌症肿瘤中过度表达的还原酶活性而被打开的结果。通过选择性地、酶催化还原组成脂质体的稳定的喹亚基亚基来实现对苯醌还原酶反应脂质体的高度特异性的失稳。对苯二酚基团的还原导致对苯二酚和脂质体双层中磷脂之间的共价键的断裂，产生不能维持双层的磷脂酰乙醇胺类脂。酶的专一性还原导致脂质体的破坏和其内容物的释放。评估这一假说的具体目的包括：1)开发具有快速NQO1催化还原和自裂解速度的人工工程的苯醌亚基，以便在整个NQO1刺激过程中产生高速率；以及2)通过优化NQO1与苯醌稳定亚基的相互作用，制造能够快速破坏NQO1激活的苯醌脂质体。这些目标将通过完成一系列精心设计的实验目标来实现，这些目标涉及合成具有热力学还原值和对酶破坏最有利的自裂解速率的醌脂类化合物，以及能够导致有效的NQO1与醌亚单位相互作用的脂质体(脂类的组成)。该项目直接涉及一类技术的开发，这些技术有可能治疗一种重要的疾病--癌症，以及与之相关的过度表达还原酶的炎性组织疾病，如类风湿性关节炎。在这项工作中将开发的方法和材料直接适用于该机构各研究所的任务，包括国家生物医学成像和生物工程研究所、国家癌症研究所和国家眼科研究所的任务。 公共卫生相关性：这项研究的目标是开发一种响应性纳米系统，该系统能够包含药物，然后通过与癌症肿瘤相关的特定蛋白的存在来刺激它们。与目前商业上可用的纳米递送系统相比，该响应系统有可能提供显著更有效的癌症肿瘤化疗治疗，且副作用更少。蛋白质反应递送系统的长期影响是巨大的，因为每年约有600万人死于癌症。

DESCRIPTION (provided by applicant): The goal of this application is to evaluate the hypothesis that the contents of vesicles (liposomes) made of redox-responsive phospholipids can be efficiently released upon liposome interaction with a specific quinone reductase enzyme that is highly concentrated in the majority of cancer tumor tissues, namely, NAD(P)H:quinone oxidoreductase type 1 (NQO1, DT-diaphorase). Demonstration of this will allow for the future development of an unprecedented group of redox-sensitive liposomes that are structurally optimized to preferentially accumulate in tumors and deliver their contents in a site-specific manner, as the result of their being opened in response to the overexpressed reductase activities in cancer tumors. Highly specific destabilization of the quinone reductase-responsive liposomes is proposed to occur by selective, enzyme-catalyzed reduction of stabilizing quinone subunits of lipids composing the liposomes. Reduction of the quinone groups leads to cleavage of the covalent link between the quinone and the phospholipid in the liposome bilayer, yielding phosphatidylethanolamine lipids that are unable to sustain bilayers. Enzyme-specific reduction leads to destruction of the liposome and release of its contents. Specific Aims to evaluate the hypothesis include that of: 1) developing synthetically engineered quinone subunits having fast speeds of NQO1-catalyzed reduction and self-cleavage so as to yield a high rate for the overall NQO1-stimulated process; and 2) making quinone-lipid liposomes capable of rapid NQO1-activated destruction by optimizing the interaction of NQO1 with the quinone stabilizing subunits. These Aims will be achieved by completion of a set of carefully designed experimental Objectives that address the synthesis of quinone-lipids having thermodynamic reduction values and self-cleavage rates that are optimal for enzymatic destruction and the formulation of liposomes (composition of lipids) that leads to efficient NQO1 interaction with quinone subunits. This project directly addresses the development of a class of technologies with the potential to treat an important disease, cancer, as well as inflammatory tissue diseases, such as rheumatoid arthritis, that have associated with them overexpressed reductase enzymes. The methods and materials to be developed during this work are directly applicable to the missions of the Agency Institutes, including those of the National Institute of Biomedical Imaging and Bioengineering, the National Cancer Institute, and the National Eye Institute. PUBLIC HEALTH RELEVANCE: This research targets the development of a responsive nanoscopic system capable of containing drugs and then delivering them upon stimulation by the presence of a specific protein associated with cancer tumors. The responsive system has the potential to provide significantly more efficient chemotherapeutic treatment of cancer tumors with fewer side effects in comparison to the current, commercially available nanoscopic delivery systems. The long-term impact of the protein-responsive delivery system is great, for roughly 6 million deaths are attributed to cancer each year.