Lipid-based Nanocapsules and Triggered Chemotherapy

该项目的目的和范围细分为两个具体目标，具体如下：具体目标1：开发具有靶向、成像和药物输送能力的多功能脂质体我们正在开发具有靶向和按需药物释放特性的基于脂质的纳米颗粒(脂质体)，以改善癌症治疗药物的输送。对于光触发应用，我们设计了由可光聚合的双乙酰磷脂(DC8，9PC)制成的脂质体，基于其在脂质体膜中的独特分配。我们的配方还包括一种可调的水性光敏剂，以促进电磁辐射引发的药物释放。对于生物应用(局部药物输送)，我们使用了不影响细胞活力的可见光光源(514 nm激光)。将脂质体/细胞悬浮液预先暴露在激光下，可提高阿霉素对细胞1的输送效率(基于细胞毒性分析)。我们用人鼻咽癌(KB)-异种移植小鼠模型进行的动物实验表明，DPPC：DC8，9PC脂质体与对照(DC8，9PC-)脂质体具有相似的生物分布。我们正在进一步开发这些脂质体，用于体内的药物输送应用。为了改善乳腺癌的治疗，我们将HER2特异性亲和体分子的靶向潜力与脂质体(HER2+亲和体)的温敏特性结合在一起。我们已经通过细胞培养实验成功地证明了HER2+亲和体能作为脂质体在细胞内传递的合适载体。这些用于输送抗癌药物的纳米颗粒的进一步开发将被证明有利于乳腺癌的治疗。具体目标2.放射诱导和靶向化疗的发展(RITCH)。这一概念设想了一种无毒的前药，当静脉给药时，它将分布在全身。当前药物受到局部电磁辐射时，它将在肿瘤部位经历化学转化为细胞毒性化合物。我们已经使用了疏水性膜探针碘-萘叠氮化物(INA)作为原型，它在光照射下与膜蛋白的跨膜部分发生共价反应。INA的光激活会影响许多细胞受体的信号传递能力，导致细胞死亡。由于INA治疗消除了除其他膜蛋白外的多药转运蛋白功能，这种方法对治疗多药耐药肿瘤是有利的。INA以膜蛋白为靶点的独特作用机制为化疗提供了一种新的有效途径。最近，我们观察到交替的辐射方式(如声空化和X射线辐射)可以触发Ritch化合物的反应性。我们计划使用各种触发模式，包括光、声空化和X射线辐射，在体外和体内测试我们的Ritch化合物的有效性。动物研究涉及药代动力学、生物分布和毒性，使用NCI-Frederick的小动物成像设施。我们正在设计新的Ritch化合物，它将更容易适应各种触发模式。此外，我们正在对新化合物的化学以及导致细胞凋亡和细胞死亡的细胞生物学事件进行基础研究。

The purpose and scope of this project is subdivided in two specific aims that are detailed below:Specific Aim 1: Develop Multifunctional Liposomes with Targeting, Imaging and Drug Delivery Capabilities We are developing lipid-based nanoparticles (liposomes) bearing targeting and on-demand drug release properties for improved delivery of cancer therapeutics. For light-triggered applications, we have designed liposomes from a photopolymerizable diacetylenic phospholipid (DC8,9PC), based on its unique partitioning in the liposome membrane. Our formulations also include a tunable aqueous photo-sensitizer to promote electromagnetic radiation-triggered drug release. For biological applications (localized drug delivery), we have used a visible light source (514 nm laser) that does not affect cell viability. Pre-exposure of liposome/cell suspensions to the laser results in improved efficiency of doxorubicin delivery to cells1 (based on cytotoxicity assays). Our animal studies using the human nasopharyngeal carcinoma (KB)-Xenograft mouse model show that DPPC: DC8,9PC liposomes show similar biodistribution when compared with control (DC8,9PC minus) liposomes. We are further developing these liposomes for their drug delivery applications in vivo. To improve breast cancer treatment, we have coupled the targeting potential of HER2-specific Affibody molecules with the thermosensitive properties of liposomes (HER2+ Affisomes). We have successfully demonstrated using cell culture experiments that the HER2+ Affisomes are suitable vehicles for intracellular delivery of liposome-entrapped contents. Further development of these nanoparticles for delivery of anti-cancer agents will prove to be beneficial for breast cancer treatment. Specific Aim 2. Development of Radiation Induced and Targeted Chemotherapy (RITCH).The concept envisions a non-toxic pro-drug that when administered intravenously will distribute throughout the body. When the pro-drug is subjected to localized electromagnetic radiation it will undergo a chemical transformation into a cytotoxic compound at the site of the tumor. We have used as a prototype the hydrophobic membrane probe Iodonaphthyl-azide (INA), which upon light irradiation undergoes a covalent reaction with transmembrane portions of membrane proteins. Photo-activation of INA affects the signaling capabilities of numerous cellular receptors and results in cell death. Since the INA treatment eliminates multidrug transporter function in addition to other membrane proteins, this approach is advantageous for treatment of multidrug resistant tumors. The unique mechanism of action INA targeting membrane proteins thus provides a novel and potent chemotherapeutic approach. Recently we observed that alternate radiation modalities (e.g. sono-cavitation and X-ray radiation) can trigger the reactivity of RITCH compounds. We plan to examine efficacy of our RITCH compounds in vitro and in vivo using various modes of triggering that include light, sono-cavitation and X-ray radiation The animal studies involve pharmacokinetics, bio-distribution and toxicity using the small animal imaging facility at NCI-Frederick. We are designing new RITCH compounds that will be more amenable to various triggering modes. In addition we are pursuing basic studies on the chemistry of the new compounds as well on cell biological events that lead to apoptosis and cell death.