目的：观察Rac1蛋白在结直肠癌细胞中的表达，并分析其与结直肠癌LoVo细胞骨架、细胞周期和细胞凋亡的相关性。方法：Western blotting测定5种结直肠癌细胞株（LoVo,SW480,SW620,SW1116,HT29)中Rac1蛋白的表达；Rac1-shRNA质粒转染LoVo细胞后，激光共聚焦显微镜观察LoVo细胞骨架的变化，流式细胞仪检测细胞周期和细胞凋亡的变化。结果：5种结直肠癌细胞株中均有Rac1蛋白的高表达。Rac1基因沉默后，LoVo细胞中交联状态的F-actin网明显减少且紊乱，G0/G1期细胞比例较对照组显著增加\[（74.63±4.40）% vs（56.46±3.09）%，P<0.05\]，而S期细胞比例较对照组显著减少\[（1287±1.77）% vs （29.66±1.92）%，P<0.05\]；Rac1-shRNA转染组LoVo细胞凋亡率较对照组显著增加\[（25.31±205）% vs （9.38±1.16）%，P<0.05\]。结论：RNA沉默Rac1基因的表达影响了LoVo细胞骨架的形成和细胞周期，为以Rac1为靶点治疗结直肠癌提供了实验依据。

Objective:To detect the expression of Rac1 protein in colorectal cancer cells and to observe its correlation with cytoskeleton, cell cycle and apoptosis of colorectal cancer LoVo cells. Methods: The expression of Rac1 protein was detected by Western blotting in five colorectal cancer cell lines. The cytoskeleton changes were observed by confocal microscopy in LoVo cells transfected with Rac1-shRNA. The cell cycle and apoptosis were observed by flow cytometry in LoVo cells transfected with Rac1-shRNA. Results: Rac1 protein was highly expressed in five colorectal cancer cells. The cross-linked F-actin network was significantly reduced and disordered in LoVo cells transfected with Rac1-shRNA. The cell number in G0/G1 phase was significantly increased in Rac1-shRNA group compared with the control group (\[74.63±440\]% vs \[56.46±3.09\]%，P<0.05), whereas it was reduced in S phase (\[12.87±1.77\]% vs \[29.66±192\]%，P<0.05) and the apoptosis rate of LoVo cells was significantly increased in Rac1-shRNA group compared with the control group (\[25.31±2.05\]% vs \[9.38±1.16\]%, P<0.05). Conclusion: Silencing Rac1 expression mediated by RNA interference affects the formation of cytoskeleton and the cell cycle of LoVo cells, which provides clinical evidence for Rac1-targeted treatment of colorectal cancer.

济南市科技局基金资助项目（No. 2007-153）；济南市卫生局基金资助项目（No. 2008-089）