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目的应用化学修饰的小干扰RNA(si RNA)阻断裸鼠乳癌移植瘤中血管内皮生长因子C(VEGF-C)基因,探讨其对人乳癌MCF-7裸鼠移植瘤生长的影响。方法于雌裸鼠皮下种植MCF-7细胞,将成瘤阳性的裸鼠随机分为VEGF-C si RNA处理组、脂质体组和对照组,每组5只。VEGF-C si RNA处理组肿瘤局部注射VEGF-C si RNA1 mg/kg和PEITM,脂质体组肿瘤局部注射PEITM和PBS,对照组仅注射PBS,每3 d注射1次,连续注射8次。22 d后拉颈处死全部动物,取肿瘤,采用半定量RT-PCR分析VEGF-C mRNA水平,Western blotting检测VEGF-C蛋白表达水平。结果VEGF-C si RNA处理组瘤组织的增长受到明显抑制,VEGF-C基因的mRNA和蛋白表达水平显著降低(F=73.64~197.15,q=8.74~25.56,P<0.05)。对照组各指标无显著变化。结论化学修饰的si RNA介导的RNAi在体内能成功下调人乳癌裸鼠移植瘤中VEGF-C基因的表达,抑制肿瘤的生长,是潜在的肿瘤基因治疗新方法。
OBJECTIVE: To study the effect of chemically modified small interfering RNA (si RNA) on the expression of vascular endothelial growth factor C (VEGF-C) gene in human breast cancer xenografts in nude mice and to investigate its effect on the growth of transplanted human breast cancer MCF-7 nude mice. Methods MCF-7 cells were implanted subcutaneously into nude mice. The tumor-positive nude mice were randomly divided into VEGF-C si RNA-treated group, lipofectamine group and control group, with 5 mice in each group. The VEGF-C si RNA-treated tumors were locally injected with 1 mg / kg VEGF-C si RNA and PEITM. The liposome group was injected with PEITM and PBS locally. The control group was injected with PBS only once every 3 days for 8 consecutive injections. Twenty-two days later, all the animals were sacrificed by neck-pulling and the tumors were harvested. VEGF-C mRNA level was analyzed by semi-quantitative RT-PCR and VEGF-C protein expression by Western blotting. Results The growth of tumor tissue was significantly inhibited by VEGF-C si RNA, and the mRNA and protein expression of VEGF-C gene was significantly decreased (F = 73.64 ~ 197.15, q = 8.74 ~ 25.56, P <0.05). There was no significant change in each index of the control group. Conclusion Chemically modified si RNA-mediated RNAi can successfully down-regulate the expression of VEGF-C gene in human breast cancer xenografts in nude mice and inhibit the growth of the tumor. It is a potential new method for gene therapy of tumors.