靶向抑制PIM-1基因对人前列腺癌裸鼠移植瘤生长的影响

摘要

目的 探讨RNA干扰(RNAi)靶向沉默PIM-1基因对人前列腺癌裸鼠移植瘤体内生长的影响.方法 12只裸鼠经腋窝下注射前列腺癌细胞(PC-3)建立人前列腺癌裸鼠移植瘤模型.建模后将荷瘤裸鼠随机分为干扰质粒组(瘤体内注射PIM-1特异性RNAi重组质粒PPIM1-shRNA-3)、空载体组(空质粒)和阴性对照组(脂质体),每组4只;每隔2d注射1次,共注射5次.实验期间测量肿瘤体积,绘制肿瘤生长曲线.处理结束后处死动物,测量肿瘤质量,计算抑瘤率.分别采用RT-PCR及Western blot技术检测各组肿瘤标本PIM-1、c-MYC mRNA和蛋白表达情况,免疫组化染色观察各组肿瘤标本PIM-1的表达.结果 成功构建人前列腺癌裸鼠移植瘤模型.分组处理后第6天开始,干扰质粒组的肿瘤体积明显小于空载体组和阴性对照组,抑瘤效果明显,同时PIM-1 mRNA及蛋白表达水平均低于空载体组和阴性对照组,PIM-1免疫组化染色亦得出相同结果 .干扰质粒组肿瘤组织c-MYC mRNA含量与另2组无明显差异,但c-MYC蛋白的表达明显低于其他2组.结论 RNAi靶向沉默PIM-1可明显抑制前列腺癌移植瘤的生长,并在翻译水平降低c-MYC蛋白的表达,PIM-1可能是前列腺癌基因治疗的有效靶点.%Objective To study the effect of PIM-1 gene silence by RNA interference (RNAi) on the growth of human prostate cancer xenograft tumor in nude mice. Methods The xenograft tumor model of human prostate cancer was established by injecting PC-3 cells in armpits of 12 nude mice. After modeling, the nude mice were randomly divided into three groups: interference plasmid group (injecting with RNAi recombinant plasmid), empty plasmid group and negative control group (liposome every), 4 mice in each group. Mice were injected every 2 days for 5 times. The tumor volumes of xenografts were measured during experiment, and the curve of tumor growth was drawn accordingly. The quality of tumor was measured, and the inhibitory rate of tumor was calculated at the end of the experiments. The expression levels of PIM-1, c-MYC mRNA and protein in xenograft tumors were detected by real-time PCR and Western blot assay, respectively. Furthermore, immunohistochemistry staining was used to verify the expression of PIM-1. Results The xenograft tumor model of human prostate cancer was established successfully. The volume of tumor was significantly decreased 6 days after the injection treatment in interference plasmid group than that of empty plasmid group and negative control group. The effect of suppressing tumor growth was remarkable. The expression levels of PIM-1 mRNA and protein were down-regulated significantly in interference plasmid group than those of other two groups. The immunohistochemical staining of PIM-1 showed the same changes. There was no significant difference in c-MYC protein level between the three groups. But interestingly, the c-MYC mRNA level was significantly decreased in interference plasmid group than that of other two groups. Conclusion The silence of PIM-1 gene by RNAi recombinant plasmid can result a significant growth suppression of the human prostate cancer xenograft tumors in nude mice. The expression of c-MYC gene is down-regulated at translation level in the therapeutic group concomitantly. PIM-1 may be a promising target of gene therapy for prostate cancer.