Aptamer-siRNA Chimera/Nanoparticle Conjugates for MRI Guided Cancer Therapy

描述（由申请人提供）：现代医学的主要挑战之一是开发用于有效递送治疗剂和病理学的分子特异性治疗的新方法，其可以在成像引导和监测下进行。纳米技术、生物化学和分子生物学的最新进展为将所有这些能力联合收割机结合在一个实体中提供了机会。在这项研究计划中，我们将利用纳米技术和生物化学的最新成就来设计具有治疗和MRI对比增强能力的纳米材料。该材料将提供以下的优化组合：失活治疗化合物的有效递送、使用外部刺激的前药的选择性活化、活化后的分子特异性治疗效果以及MRI监测和引导。该纳米材料将由金涂层的氧化铁纳米颗粒载体组成，该载体带有连接的寡核苷酸手柄，该手柄通过互补核苷酸与氟化适体-siRNA嵌合体分子相互作用。嵌合体的适体部分将对癌症生物标志物具有特异性，并且siRNA部分将用于下调癌细胞存活所必需的基因的表达。寡核苷酸柄将被设计为与嵌合体的适体部分相互作用并可逆地失活;这将确保颗粒不会自发地结合其靶标，特别是在正常组织中。这些生物缀合的纳米颗粒将在T2加权MRI监测其积累和生物分布下递送到癌组织中。然后，近红外（NIR）照射将被递送到治疗部位，这将导致金层的局部加热，寡核苷酸柄和嵌合体分子的适体部分之间的双链螺旋的熔化，以及嵌合体的释放，嵌合体然后将扩散到癌组织的深处。我们假设嵌合体分子的释放和扩散可以通过19 F MRI成像。适体部分将重新折叠并重新获得分子特异性，将治疗性siRNA递送到癌细胞内，从而诱导细胞死亡。纳米颗粒载体将改善递送，降低非特异性毒性，并能够监测分子特异性癌症治疗的积累和活化。细胞培养和小鼠异种移植模型的初步试验将证明其疗效。该计划的主要目标是开发并初步测试一种新的无毒纳米材料，该材料可以通过近红外光照射激活，释放出一种靶向分子化合物，该化合物可以被癌细胞选择性内化，并诱导治疗性基因沉默反应。纳米颗粒载体将改善递送，降低非特异性毒性，并能够监测分子特异性癌症治疗的积累和活化。小鼠异种移植模型的初步试验将证明其疗效。该项目的成功完成将为实现癌症医学的最终目标之一，即可用于同时检测和治疗癌症的材料，取得重要进展。

DESCRIPTION (provided by applicant): One of the major challenges of modern medicine is the development of novel approaches for the efficient delivery of therapeutics and molecular specific treatment of pathology that can be carried out under imaging guidance and monitoring. Recent advances in nanotechnology, biochemistry and molecular biology give an opportunity to combine all these capabilities in a single entity. In this research program we will use recent achievements in nanotechnology and biochemistry to engineer a nanomaterial with both therapeutic and MRI contrast enhancing capabilities. This material will provide the optimized combination of: efficient delivery of a deactivated therapeutic compound, selective activation of the prodrug using external stimuli, molecular specific therapeutic effect upon activation and MRI monitoring and guidance. The nanomaterial will consist of a gold-coated iron oxide nanoparticle carrier with attached oligonucleotide handles that interact with fluorinated aptamer-siRNA chimera molecules through complementary nucleotides. The aptamer portion of the chimera will be specific for a cancer biomarker and the siRNA portion will be used to down-regulate expression of genes that are essential for cancer cell survival. The oligonucleotide handle will be designed to interact with and reversibly deactivate the aptamer portion of the chimera; this will ensure that the particles do not spontaneously bind to their target especially in normal tissue. These bioconjugated nanoparticles will be delivered in cancerous tissue under T2 weighted MRI monitoring of their accumulation and biodistribution. Then, near infrared (NIR) irradiation will be delivered to the treatment site that will lead to the local heating of the gold layer, melting of the double stranded helix between oligonucleotide handles and the aptamer portion of chimera molecules, and release of the chimeras which will then diffuse deep into the cancerous tissue. We hypothesize that release and diffusion of chimera molecules can be imaged by 19F MRI. The aptamer portion will refold and regain molecular specificity, delivering the therapeutic siRNA inside cancer cells thereby inducing cell death. The nanoparticle carrier will improve delivery, reduce non-specific toxicity, and enable monitoring of accumulation and activation of molecular specific cancer therapy. Initial tests with cell cultures and mouse xenograft models will demonstrate its efficacy. The main objective of this program is to develop and initially test a new, nontoxic nanomaterial that can be activated via NIR light irradiation to release a targeted molecular compound that can be selectively internalized by cancer cells and induce a therapeutic gene-silencing response. The nanoparticle carrier will improve delivery, reduce non-specific toxicity, and enable monitoring of accumulation and activation of molecular specific cancer therapy. Initial tests with mouse xenograft models will demonstrate its efficacy. Successful completion of this project will make an important advance toward realization of one of the ultimate goals of cancer medicine, a material that can be used to simultaneously detect and treat cancer.