聚酰胺-胺型树枝状高聚合物介导survivin反义寡核苷酸抑制结直肠癌裸鼠皮下移植瘤生长的作用

Polyamidoamine dendrimer-mediated survivin antisense oligonucleotide inhibits the growth of subcutaneously transplanted colorectal cancer in nude mice

目的探讨聚酰胺-胺型树枝状高聚合物(PAMAM)介导survivin反义寡核苷酸(survivin-ASODN)对结直肠癌裸鼠移植瘤的抑制作用。方法以人结直肠癌细胞SW620裸鼠皮下注射建立结直肠癌裸鼠皮下移植瘤模型,将PAMAM和阳离子脂质体分别与survivin-ASODN混合得到载反义基因转染复合物。透射电镜观察复合物的形态,激光散射粒径分析仪测定粒径,zeta电位分析仪测定复合物的zeta电位,离心法和紫外分光分度仪测定复合物的包封率和体外DNA释放速度。将两种反义基因复合物注射裸鼠移植瘤体内,观察两组移植瘤体积,Western bloting方法检测移植瘤组织中survivin基因的表达。结果PAMAM-survivin-ASODN复合物的粒径小于脂质体-survivinASODN复合物的粒径(P<0.01),而zeta电位高于PAMAM-survivin-ASODN复合物zeta电位(P<0.05),基因包封率两组无显著差异。PAMAM对DNA持续释放达14d,但脂质体复合物只持续5d。PAMAM-survivin-ASODN复合物治疗组裸鼠移植瘤survivin蛋白表达低于脂质体-survivin-ASODN复合物组(P<0.05)。PAMAM-survivin-ASODN复合物治疗组移植瘤体积低于脂质体-survivin-ASODN复合物组(P<0.05)。结论PAMAM能将survivin-ASODN高效递送到结直肠癌移植瘤细胞,降低survivin蛋白的表达,抑制移植瘤生长。

Objective To evaluate the inhibitory effects ofsurvivin antisense oligonucleotide （survivin-ASODN） mediated by polyamidoamine dendrimer （PAMAM） against the growth of subcutaneously transplanted colorectal cancer in nude mice. Methods Nude mouse models bearing colorectal cancer was established by subcutaneous injection of SW620 cells. Surrivin- OSADN （300 μg/L） was mixed with 4.06 μg/L PAMAM or liposome to prepare two transfection complexes, and their morphologies were observed by transmission electron microscope. The particle size of the prepared complexes was determined by laserparticle size analyzer, and the zeta potential was measured. The encapsulation efficiency and the DNA release rate in vitro were determined by ultraviolet spectrophotometer. The transfection complexes were then directly injected into the xenografls of the tumor-beating nude mice. The tumor volume changes were observed, and the expression of survivin in the transplanted tumor was measuredbyWestem blotting Results The PAMAM-survivin-ASODN complex had a significantly smaller diameter and greater zeta potential than liposome-survivin-ASODN （P〈0.01 and 0.05, respectively）. The encapsulation efficiency was comparable between the two complexes. In in vitro condition, PAMAM-survivin-ASODN allowed sustained survivin-ASODN release for as long as 14 days, as compared with the 5 days for the liposome complex. After injection into the tumor xenografts, PAMAM-survivin- ASODN resulted in significantly lower expression ofsurvivin protein in the transplanted tumors （P〈0.05）, and also in significantly greater reduction of the tumor volume than the liposome complex （P〈0.05）. Conclusion PAMAM can effectively deliver survivin-ASODN into transplanted colorectal tumor cells to reduce the expression of survivin and inhibit the tumor growth.