纳米转运系统介导microRNA靶向沉默HIF-1α和Survivin对鼻咽癌放疗敏感性的影响及机制探讨

Radiotherapy is the most important primary treatment for Nasopharyngeal carcinoma. Radioresistance is the major obstacle that often lead to the failure of clinical cancer therapy. Both anoxic cell ratio and apoptosis inhibition are important factors which affects the sensitivity to radiation. HIF-1 gene is related to hypoxia of tumor cells. It may be beneficial to tumor cells survival and proliferation in hypoxia condition. Survivin is by far the strongest member of antiapoptotic proteins up to now. Owing to its special structure and surface charge, nano has high efficiency of gene transfer. Integration of exogenous genes to the host cell chromosomal DNA can be mediated by nano. Nano can also protect transduction gene against destruction which originated from variety of enzymes in the body plasma or the complements of tissue cells. Non-immunogenic, non-genotoxic and cytotoxic are its characteristics of nano. If HIF-1 gene and survivin can be combined effectly, meanwhile nanoparticles as gene transfection vectors will be used because of its efficiency, security, targeting and controlled release, targeting HIF-1 and survivin micro of RNA into nasopharyngeal carcinoma cells, thereby blocking their function. Based of above, in conjunction with radiation therapy , the treatment of NPC will be more specific and effective. It may be a new breakthrough to enhancing tumor sensitivity to radiotherapy in the nasopharyngeal carcinoma.

放疗是鼻咽癌主要治疗手段,但部分患者对放疗不敏感，常不能得到满意的治疗效果。乏氧细胞的比例及细胞凋亡抑制是影响细胞放射敏感性的重要因素。肿瘤的缺氧状态和HIF-1α的表达水平相关, HIF-1α使肿瘤细胞能在缺氧的环境中存活和生长。Survivin是迄今发现最强的凋亡抑制因子。纳米载体特殊的结构及表面电荷，使其具有很高的基因转移效率，可介导外源基因在宿主细胞中的整合，可保护转导基因不受机体血浆，或组织细胞中各种补体以及各种酶的破坏，无免疫原性，无遗传毒性和细胞毒性。如果将HIF-1α和Survivin这两个靶基因有效联合，运用纳米颗粒作为基因转染载体，将靶向HIF-1α和Survivin的micro RNA导入鼻咽癌细胞，阻断鼻咽癌HIF-1α和Survivin表达，同时配合放射治疗，将会使抗肿瘤治疗更加特异有效，并可能从放射增敏的角度为鼻咽癌的特异基因治疗寻找一个新的突破点。

放疗是鼻咽癌主要治疗手段,但部分患者对放疗不敏感，常不能得到满意的治疗效果。乏氧细胞的比例及细胞凋亡抑制是影响细胞放射敏感性的重要因素。肿瘤的缺氧状态和HIF-1α的表达水平相关, HIF-1α使肿瘤细胞能在缺氧的环境中存活和生长。Survivin是迄今发现最强的凋亡抑制因子。纳米载体特殊的结构及表面电荷，使其具有很高的基因转移效率，可介导外源基因在宿主细胞中的整合，可保护转导基因不受机体血浆，或组织细胞中各种补体以及各种酶的破坏，无免疫原性，无遗传毒性和细胞毒性。如果将HIF-1α和Survivin这两个靶基因有效联合，运用纳米颗粒作为基因转染载体，将靶向HIF-1α和Survivin的micro RNA导入鼻咽癌细胞，阻断鼻咽癌HIF-1α和Survivin表达，同时配合放射治疗，将会使抗肿瘤治疗更加特异有效，并可能从放射增敏的角度为鼻咽癌的特异基因治疗寻找一个新的突破点。课题组成功构建PEI-Fe3O4磁性纳米粒，并成功转染包被miRNA-HIF-1α质粒和miRNA-Survivin质粒的PEI-Fe3O4磁性纳米粒到鼻咽癌CNEII细胞中，H组、S组、HS组转染率分别为55.3%±6.5%、48.1%±2.3%、46.6%±4.1%。体内外实验，在分子水平及蛋白水平均能沉默靶基因。沉默靶基因后的鼻咽癌细胞凋亡增加，S组、HS组与NC组相比，凋亡平均增加1.97倍、1.46倍。施以放射线照射后凋亡增加更为明显，H组、S组、HS组凋亡率相比于NC组分别平均增加4.00倍、3.40倍、3.67倍。本项目从基因放射增敏的角度来阻断肿瘤细胞的生长，从而为鼻咽癌的特异放射增敏基因治疗的研究开辟一条新途径，在转染载体的选择上提供一个新的研究思路，为今后进行系列基因放射增敏研究奠定良好的基础。