复合miRNA-302b的磁性纳米粒靶向治疗骨肉瘤的系统研究

Magnetic nanoparticles are becoming a popular drug delivery system for their remarkable advantages in reducing the toxicity of chemotherapeutic drugs and enhancing the efficiency of the drugs in targeted tissues. Our group has successfully designed and composed adriamycin–polybutylcyanoacrylate magnetic nanoparticles (ADR–PBCA-MNPs) in the treatment of osteosarcoma. These magnetic nanoparticles have shown to have good stability, high specificity and are capable of increasing adriamycin concentration at tumor sites. Meanwhile, our group has acquired an osteosarcoma microRNA (miRNA) differential expression map by performing miRNA screenings on osteosarcoma cell lines. We found that the overexpression of miRNA-302b in osteosarcoma U2OS and MG-63 cells could lead to significantly suppressed cell proliferation, reduced cell cycle progression, and increased cell apoptosis. Based on these findings, we propose to establish a miRNA-302b magnetic nanoparticle delivery system to specifically deliver miRNA-302b to osteosarcoma tissues and reduce their off-target side effects. We plan to first test the characteristics and physicochemical properties of this novel miRNA delivery system and study its biological effects in vitro using osteosarcoma cell lines. We will then study the in vivo distribution and safety of these nanopaticles on an animal model using C57BL/6 mice. Lastly, we will examine the targeting performance of these novel nanoparticles by applying a local magnetic field to tumor-bearing mice .This system is promising to be applied into clinical use as an alternative to conventional chemotherapy by providing osteosarcoma patients with a highly specific and non-toxic treatment option.

降低化疗的毒副作用、增强化疗药物的治疗靶向性是提高化疗效果的主要策略，磁性纳米粒靶向给药系统与该领域备受关注。本课题组已成功制备磁性纳米粒结合表阿霉素的复合物，其稳定性好，靶向特异性高，可有效提高肿瘤组织中化疗药物浓度。另外，我们研究报道了骨肉瘤细胞的miRNA差异性表达谱，进一步研究发现调控miRNA-302b的表达水平能有效抑制骨肉瘤细胞生物学行为，抑制细胞生长和细胞周期，增加细胞凋亡。在上述研究基础之上，本课题拟构建miRNA-302b与磁性纳米粒靶向系统，检测其表观特征和理化性质，验证其对骨肉瘤细胞的生物学作用，观察在小鼠体内的安全性、自然分布和靶向效果，以证明该复合物具有较好的靶向性，能特异性作用于病变组织，提高化疗疗效，有效的避免化疗药物的毒副作用，为骨肉瘤的分子治疗提供新的思路。

骨肉瘤患者治疗的五年生存率在近10年没有进展，这与化疗耐药、副作用及肿瘤细胞异质性等原因密切相关。降低化疗的毒副作用、增强化疗药物的治疗靶向性是提高化疗效果的主要策略，磁性纳米粒靶向给药系统与该领域备受关注，miRNA纳米载药系统与靶向治疗可能是提高骨肉瘤治疗效果的新方向。本项目的研究基础是，成功制备磁性纳米粒结合表阿霉素的复合物，研究报道了骨肉瘤细胞的miRNA差异性表达谱，并首次发现调控miRNA-302b的表达水平能有效抑制骨肉瘤细胞生物学行为。本项目的主要研究内容：制备及表征载miRNA302b(miR302b)的磁性纳米粒系统(miR302b-DMNPs)，② 研究miRNA302b通过靶向抑制Runx2抗骨肉瘤的生物学作用及机制，③ 探讨miRNA99a抑制骨肉瘤生物学作用及其机制。本项目完成了miR302b-DMNPs磁性纳米粒系统的合成和基本表征，该磁性纳米粒具备较好的靶向性，能提高miR302b的基因治疗疗效，避免化疗药物的毒副作用。本项目证实了miR-302b与骨肉瘤患者临床特征的关系；细胞水平研究结果表明，miR302b高表达抑制143B 和MG-63 细胞的增殖、侵袭和迁移，miR302b靶向作用于143B细胞的Runx2基因，并且，高表达Runx2逆转了miR302b 在143B细胞的抑制效应；动物水平研究表明miR302b抑制原位骨肉瘤裸鼠模型瘤体生长和肺转移癌。本项目还研究表明，miR99a在骨肉瘤细胞系中相对表达高于其他肿瘤细胞系，miR-99a抑制物促进了骨肉瘤细胞凋亡，并抑制了骨肉瘤细胞侵袭和迁移能力。