Effects of RNAi-mediated knockdown of Rac1 gene on growth and transplanted tumors of colon cancer SW480 cells in nude mice

XIE Na; HUANG Yousheng; LUO Zhifei; XUE Fenggui

doi:10.3969/j.issn.1002-266X.2016.40.001

Abstract：Objective To investigate the effects of Rac1 gene silenced by RNA interference (RNAi) on cell prolifera-tion and growth of subcutaneous tumor of colon cancer SW480 cells in nude mice.Methods ① Cell experiment: colon cancer SW480 cells cultured in vitro were randomly divided into the blank control group, negative control group, and shRNA-Rac1 group.Recombinant lentivirus virus vector ( NC-shRNA and Rac1-shRNA) were constructed and were respectively transfected into negative control group and shRNA-Rac1 group.The expression levels of Rac1 mRNA and protein were meas-ured by quantitative real-time polymerase chain reaction ( qRT-PCR) , and Western blotting, respectively.Cell proliferation at 24, 48, 72, and 96 h after transfection was determined by MTT.②Animal experiment:cells from shRNA-Rac1 group and negative control group were planted into nude mice to establish mice models of colon cancer ( observation group and control group) .Formulation and growth of the tumor was observed.After the mice were sacrificed by cervical dislocation, tumor tis-sues were removed completely and we measured its weight and size.Meanwhile, Rac1expression was also detected by immu-nohistocytochemistry.Results ①cell experiment:Compared with the blank control group and negative control group, the expression of Rac1 mRNA and protein in the shRNA-Rac1 group decreased significantly (all P<0.05).The proliferation a-bility of colon cancer cells was significantly inhibited in the shRNA-Rac1 group at all detecting time points as compared with that of the control group (all P<0.05).②Animal experiment:tumor was observed in all cases of the control group 4-8 days after the transplantation.While in the observation group, tumor was only observed in 2 cases 35 days after the transplanta-tion, and it took 10 days longer to form a tumor than that in the control group.On the 35th day of transplantation, average volume of the tumor in the observation group and control group was (948.13 ±523.50) and (32.54 ±43.13) mm3 , and the tumor average weight was respectively (0.873 ±0.372) and (0.023 ±0.031) g, and significant difference was found be-tween the two groups (all P<0.01).Besides, compared with the control group, the expression rate of Rac1 in the observa-tion group was significantly lower than that in the control group (P<0.01).Conclusion Silencing the expression of Rac1 decreases the proliferation of colon cancer cells SW480 and inhibits the tumor formation in nude mice.