敲减血管内皮生长因子受体-2表达抑制人乳腺癌裸鼠移植瘤的生长

应用化学修饰的小干扰RNA(small interference RNA,siRNA)抑制裸鼠乳腺癌移植瘤血管内皮生长因子受体-2基因（VEGFR2,又称kinase insert domain-containing receptor, KDR)的表达, 探讨抑制肿瘤血管生成对人乳腺癌(MCF-7)裸鼠移植瘤生长的影响．雌裸鼠皮下种植MCF 7 细胞,肿瘤长至一定大小时, 随机分为对照组（A）、转染试剂对照组（B）、小剂量治疗组（C）及大剂量治疗组（D）．肿瘤局部分别注射葡萄糖溶液、In vivo jetPEI^TM转染试剂和In vivo jetPEI^TM转染试剂包裹的KDRsiRNA．22 d后处死全部动物, 取肿瘤, 测其大小及重量, HE 及免疫组化染色,微血管密度计数，同时用RT-PCR检测KDR基因的表达水平．结果显示，siRNA治疗组瘤组织的增长受到明显抑制；HE染色显示,治疗组肿瘤中心区出现大面积细胞坏死；免疫组化结果显示,染色阳性血管数明显低于对照组；同时RT-PCR结果表明,治疗组KDR表达下调．对照组各指标无显著变化．因此，化学修饰的siRNA介导的RNAi可以降低人乳腺癌裸鼠移植瘤血管中KDR 表达, 抑制血管生成进而抑制肿瘤的生长，是潜在的肿瘤治疗新方法．

Knock-down of Kinase Insert Domain-containing Receptor Gene Expression Retards Transplantation Tumor Growth

The chemically modified siRNA was used to inhabit VEGFR2 (kinase insert domain-containing receptor, KDR) gene expression on new vessels of breast cancer and affected on the growth of transplantation tumor(MCF-7 breast cancer cells) in nude mice by inhibiting the growth of tumor vessels. MCF -7 breast cancer cells were implanted under the skin of female nude mice. After the tumors grew up to a definite size, the mice were randomly divided into four groups: control group(A), transfecting agent group(B), small dose treatment group(C) and big dose treatment group(D).The tumor was respectively injected with 5% glucose, transfecting agent(in vivo jetPEI~ TM ) and transfecting agent(in vivo jetPEI~ TM ) with small dose or big dose KDR siRNA. All animals were killed after 22 days.The tumors were taken out and their size and weight were measured.HE dyeing and immunohistochemical( IHC ) analysis was conmpleted, and RNA expression of KDR gene in tumor vessels was examined by RT-PCR. In KDR siRNA treated groups, the tumor growth was visibly suppressed. HE dyeing showed that there were large areas of cytoclasis in the center of tumors. And immunohistochemical( IHC ) analysis showed that the immunoreactivity was decreased significantly. Furthermore, RT-PCR results indicated that KDR mRNA expression was decreased. In contrast, there were no obvious changes in control groups. Therefore, RNAi mediated by chemically modified siRNA greatly decreased KDR gene expression in the transplantation tumor vessels of nude mice, inhibited the growth of new vessels and also suppressed the tumor growth. It may be a potential method to treat human cancer.