Drug Resistance in Cancer Therapy

描述（由申请人提供）：本探索性提案的目的是研究我们最近开发的纳米颗粒制剂克服癌症治疗中耐药性问题的功效。观察到修饰的纳米颗粒在其细胞摄取后定位在细胞核中和周围，并且保留在细胞内，即它们不经历胞吐作用。因此，假设修饰的纳米颗粒将直接将包封的药物递送至细胞核，而不暴露于膜结合的外排转运蛋白和细胞质因子（例如，药物在酸性囊泡中的降解或积累），其限制了抗肿瘤剂在抗性细胞中的核递送。因此，使用修饰的纳米颗粒的药物的直接核递送将克服耐药性的问题，因此该疗法在肿瘤消退中将更有效。我们将使用阿霉素作为模型药物，因为它通过嵌入核DNA起作用。为了检验上述假设，我们将测量药物在正常和耐药乳腺癌细胞系中的抗增殖活性（IC 50），并确定各种细胞内隔室（细胞核、细胞质、内-溶酶体）中的药物水平，以了解修饰纳米颗粒的更大药物疗效的机制。为了测试修饰的纳米颗粒在体内给药的适用性，我们将研究它们的生物相容性，生物分布，然后通过静脉给药确定它们在乳腺癌进展的小鼠模型中的肿瘤消退的功效。该提案的具体目的是：1）测试修饰的纳米颗粒有效地将多柔比星靶向细胞核的假设，并因此克服耐药性的问题，和2）证明修饰的纳米颗粒在使用敏感（MCF-7）和耐药（MCF-7/Adr）细胞诱导的乳腺癌小鼠模型中的肿瘤消退中是有效的。在该提案中研究的纳米颗粒制剂可用作靶向为细胞核的几类治疗剂的有效递送机制。

DESCRIPTION (provided by applicant): This aim of this exploratory proposal is to investigate the efficacy of our recently developed nanoparticle formulation to overcome the problem of drug resistance in cancer therapy. Modified nanoparticles are seen to localize in and around the nucleus following their cellular uptake and are retained inside the cells i.e. they do not undergo exocytosis. Hence, it is hypothesized that modified nanoparticles would deliver the encapsulated drug directly to the nucleus without its exposure to the membrane-bound efflux transporters and cytoplasmic factors (e.g., degradation or accumulation of drug in acidic vesicles) that limit the nuclear delivery of antineoplastic agents in resistant cells. Hence, direct nuclear delivery of the drug using modified nanoparticles would overcome the problem of drug resistance and hence the therapy would be more effective in tumor regression. We will use doxorubicin as a model antineoplastic agent because it acts by intercalating with the nuclear DNA. To test the above hypothesis, we will measure the antiproliferative activity (IC50) of the drug in normal and drug resistant breast cancer cell lines and also determine drug levels in various intracellular compartments (nucleus, cytoplasm, endo-lysosomes) to understand the mechanism of greater drug efficacy with modified nanoparticles. To test the suitability of modified nanoparticles for in vivo administration, we will study their biocompatibility, biodistribution, and then determine their efficacy for tumor regression in a murine model of breast cancer progression via intravenous administration. The specific aims of the proposal are: 1) to test the hypothesis that modified nanoparticles are effective in targeting doxorubicin to the nucleus, and hence in overcoming the problem of drug resistance and 2) to demonstrate that modified nanoparticles are effective in tumor regression in a murine model of breast cancer induced using sensitive (MCF-7) and resistant (MCF-7/Adr) cells. The nanoparticle formulation investigated in this proposal could be used as an effective delivery mechanism for several classes of therapeutics for which the target is nucleus.