Effects of Rap1 GTP-activating protein on proliferation,invasion and migration of colon cancer cells
Purpose To investigate the corr-elation between Rap1 GAP expression in colon cancer tissues and clinicopatho-logical features and prognosis.Methods Immunohistochemistry was used to detect Rap1 GAP protein expression in 125 cases of colon cancer,and its correlation with clinicopathological features and prognosis was analyzed.Rap1 GAP protein expression in co-lon cancer LOVO,HCT116,SW480 cells and normal colon epi-thelial HCoEPiC cells was detected by Western blot.The expres-sion of Rap1 GAP was down-regulated and up-regulated in LO-VO,HCT116 and SW480 cells by lentivirus transfection,and di-vided into no-load group(sh-NON,LV-NON),sh-Rap1 GAP group(low expression Rap1 GAP)and LV-Rap1 GAP group(overexpression Rap1 GAP)according to different treatments.The transfection efficiency was verified by Western blotting.MTT assay and Transwell assay were used to detect cell proliferation,invasion and migration in each group.Results In 125 colon cancer samples,83 cases(66.4％)had the loss of Rap1 GAP expression,which was higher than that in paracancer control(7.2％,P＜0.001).The rate of loss of Rap1 GAP expression was correlated with the degree of tumor differentiation(x2=6.152,P=0.011)and the presence of mucinous adenocarcino-ma(x2=4.908,P=0.028),but not with gender,age,tumor location,tumor stage,or lymph node metastasis(P＞0.05).Western blotting results showed that compared with HCoEPiC(0.189±0.081)cells,Rap1 GAP protein expression was in-creased in colon cancer LOVO(0.238±0.008)cells.Rap1 GAP protein expression was decreased in HCT116(0.064± 0.002)and SW480(0.152±0.026)cells(F=159.6,P＜0.05).After LOVO cells were transfected with Rap1 GAP low expression lentivirus,the expression level of Rap1 GAP in sh-Rap1 GAP-1 group(0.733±0.071)and sh-Rap1 GAP-2 group(0.559±0.136)and sh-Rap1 GAP-3 group(0.606±0.037)was significantly lower than that in LOVO group(1.880± 0.129)(F=49.57,P＜0.05).Compared with sh-NON(1.260±0.109)group,the proliferation ability of sh-Rap1 GAP-2(1.569±0.059)and sh-Rap1 GAP-3(1.548±0.087)cells was significantly increased at 72 h(F=28.36,P＜0.05).Its invasion and migration ability were significantly increased(P＜0.05).After HCT116 cells transfected with overexpression lentivirus,the expression of Rap1 GAP protein in LV-Rap1 GAP group(1.395±0.137)was relatively higher than that in LV-NON group(0.485±0.097)(P＜0.05).The results of MTT assay showed that compared with LV-NON(0.652±0.047)group,the proliferation ability of cells in LV-Rap1 GAP(1.212 ±0.038)group was decreased,and the invasion and migration ability were significantly decreased(P＜0.05).The transfection results,proliferation,invasion and migration of SW480 cells were consistent with those of HCT116 cells.Conclusion The loss rate of Rap1 GAP expression is related to the differentiation degree of colon cancer and whether it is accompanied by mucin-ous adenocarcinoma.The up-regulation of Rap1 GAP expression can inhibit the proliferation,invasion and migration of colon cancer cells,providing a theoretical basis for exploring the occur-rence and development of colon cancer.
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