目的：制备聚酰胺胺型树枝状分子（polyamidoamine dendrimer，PAMAM-D）载送CXCR4-shRNA的纳米复合微粒（PAMAM-shRNA），研究其在体外抑制人肾癌A498细胞增殖的效应。方法：将第7代的PAMAM-D室温下与CXCR4-shRNA混合（质量比为1∶0.73），制备成纳米树形分子与CXCR4-shRNA的纳米复合物PAMAM-shRNA，采用透射电镜观察PAMAM-shRNA的形态结构，激光粒径仪测定其粒径。分别以PAMAM-shRNA、CXCR4-shRNA和PAMAM-D转染A498细胞，MTT法检测PAMAM-shRNA对肾癌细胞A498增殖的抑制作用，流式细胞术检测PAMAM-shRNA诱导A498细胞的凋亡情况，Real-time PCR分析转染后肾癌A498细胞CXCR4 mRNA的表达水平。结果：成功制备的新型纳米复合微粒PAMAM-shRNA分散性好，不粘连，其平均粒径为（176.5±25.48）nm。PAMAM-shRNA可以有效地抑制人肾癌细胞A498的增殖，且随着PAMAM-shRNA浓度和药物作用时间的增加，细胞增殖抑制的效果越明显，其最高增殖抑制率达（66.5±2.7）% ；其还可加强诱导肾癌A498细胞凋亡。Real-time PCR检测结果表明，与CXCR4-shRNA组相比，PAMAM-shRNA组的CXCR4 mRNA的表达水平明显下降\[（0.29±0.035）vs（0.70±0.084），P<0.05\]。结论： PAMAM-D能高效递送CXCR4-shRNA进入A498细胞，PAMAM-shRNA以剂量和时间依赖方式显著抑制肾癌细胞增殖和诱导肾癌细胞凋亡，其在肿瘤基因治疗中具有潜在的应用价值。

Objective: To optimize the preparation of polyamidoamine dendrimer-CXCR4-shRNA nanoparticles (PAMAM-shRNA) and study the inhibitory effect of PAMAM-shRNA nanoparticles on the proliferation of renal carcinoma cells in vitro. Methods: The seventh generation of polyamidoamine dendrimer (PAMAM-D) and CXCR4-shRNA were mixed at a mass ratio of 1∶0.73) at room temperature. The morphology and structure of PAMAM-shRNA by transmission electron microscopy, and determined the size of the nanoparticles were analyzed by laser particle size analyzer. Human renal carcinoma A498 cells were transfected with PAMAM-shRNA,CXCR4-shRNA and PAMAM-D respectively. After transfection, cell viability was assessed by MTT assays, cell apoptosis by flow cytometry, and CXCR4 mRNA abundance by Real-time PCR. Results: The prepared PAMAM-shRNA nanoparticles were evenly distributed and non-adherent with a mean diameter of 176.5±25.48 nm. PAMAM-shRNA effectively inhibited A498 proliferation in time- and dose-dependent manners, and the highest proliferation inhibition rate was up to （66.5±2.7)%. PAMAM-shRNA induced A498 cell apoptosis. CXCR4 mRNA abundance was significantly decreased (P<0.05) in cells transfected with PAMAM-shRNA (0.29±0035) than in cells transfected with CXCR4-shRNA (0.70±0.084). Conclusions: PAMAM dendrimers may efficiently mediate the entry of CXCR4-shRNA into renal carcinoma cells, where they exert proliferation-inhibitory and apoptosis-promoting activities. These observations suggest that PAMAM-shRNA nanoparticles may have a potential clinical application in gene therapy of renal cancer.

国家自然科学基金资助项目（No. 81202019）；上海市卫生局青年科研资助项目（No. 2011Y197）。