microRNA-451对人结肠癌细胞SW620裸鼠皮下种植瘤生长的抑制作用及机制探讨

Inhibiting Effect of MicroRNA-451 to Subcutaneous Implantation Tumor of Human Colorectal Cancer in Nude Mice and Probably Mechanism

目的探讨microRNA-451(miR-451)对人结肠癌细胞系SW620裸鼠皮下种植瘤生长的影响,并探讨其可能机制。方法 18只裸鼠随机分为3组,实验组(SW-620-451组)、阴性对照组(SW-620-NC)、空白对照组(SW-620组),每组6只,分别皮下接种转染miRNA-451agomir的SW620细胞、转染了阴性片段agomir Negative Control(NC)的SW620细胞和不经处理的结肠癌SW620细胞,并每周两次于瘤体内分别注射miRNA-451 agomir、miRNA-451agomir NC片段及生理盐水。比较各组裸鼠皮下形成瘤体的大小并计算抑瘤率,接种四周后处死裸鼠取组织,用免疫组化法和Western-blot法定性定量分析和比较肿瘤相关基因c-myc的表达。结果各组裸鼠皮下接种肿瘤细胞6天后均有瘤体形成,成瘤率100%,实验组(SW-620-451组)瘤体生长速度明显低于其他两组(p<0.05);时间终点为第30天时,实验组(SW-620-451组)裸鼠皮下种植瘤的体积为(0.95±0.13)cm^3,阴性对照组(SW-620-NC组)为(2 25±0.50)cm^3,空白对照组(SW-620组)为(2.46±0.59)cm^3;实验组(SW-620-451组)瘤体体积显著小于其他两组体积(p<0.05);实验组(SW-620-451组)瘤体质量为(1.15±0.13)g,明显低于SW-620-NC组(2.59±0.46)g及SW-620组(2.76±0 44)g(p<0.05)。实验组种植瘤中c-myc的表达量较另外两组下降(p<0 05)。结论转染miR-451后可以抑制结肠癌细胞SW620裸鼠皮下移植瘤的生长,其机制可能与下调c-myc表达有关。

Objective To explore the effects of mieroRNA-451 （ miR-451 ） on the growth of implanted subcutaneous tumors in human coloreetal tumor-bearing nude mice, and to investigate the potential mechanism of miR-451 as a new tumor suppressor in vivo. Methods Eighteen nude mice were allotted randomly into 3 groups ,SW-620-451 group, SW-620-NC group and SW-620 group, six mice every group. The animal model of subcutaneous implantation tumor in nude mice was established by corresponding injecting of 6 ×10^6SW-620-451 （ transfected with miR- 451agomir ）eens,SW-620-NC （transfected with agomir Nonsense Control sequence） cells and SW-620 ceils subcutaneously. The mice of three groups were respectively injected with miR-451 agomir, miR-451 agomir NC and saline twice a week. Make comparison the tumor growth in each group and calculate the tumor inhibition rate. The mice was killed in 4 weeks. The expression of c-mye in each group was examined by immunohistochemistry and Western-blotting respectively. Results Every nude mouse has tumor formation after 6 days of subcutaneous inoc- ulation with a tumor formation rate of 100%. The tumor growth rate of SW-620-451 group was significantly lower than the other two groups（p 〈0.05 ）. At the endpoint time of 30th days ,the average tumor volume of SW-620-451 group was smaller than that of SW-620-NC and SW- 620 groups [ （0. 95 ± 0. 13 ） cm3 vs. （ 2.25 ± 0. 50 ） cm3 and （2. 46 ± 0.59 ） cm3 ,p 〈 0. 05 ]. The average tumor weight of SW-620-451 group was lighter than that of SW-620-NC and SW-620 groups [ （ 1.15 ±0. 13 ） g vs. （2.59 ± 0. 46） g and （ 2.76 ± 0. 44 ） g,p 〈 0. 051. The ex- pression of c-myc in SW-620-451 group was decreased compared with that of SW-620-NC groups and SW-620 groups（p 〈0. 05 ）. Conclu- sion The high expression of miR-451 can effectively inhibit the growth of tumor in human colorectal tumor-bearing nude mice and the mech- anism maybe related to the decrease expression of c-myc protein.