中文摘要：

目的探讨下调Cullin1（Cull）基因对乳腺癌细胞增殖的影响及其机制。方法利用脂质体将靶向Cull基因小干扰RNA（siRNA）、对照siRNA分别转染人乳腺癌MDA—MB-231和BT-549细胞，Westernblot技术检测Cull基因表达，细胞计数试剂盒（CCK-8）比色法检测细胞增殖，流式细胞仪检测细胞周期变化，Westernblot检测细胞周期蛋白（Cyclin）A、CyclinD1、CyclinE以及细胞周期蛋白依赖性激酶抑制因子p21和p27表达。结果与对照组比较，转染CullsiRNA48h后MDA—MB-231和BT-549细胞Cull蛋白表达明显降低；细胞增殖明显减慢，72h和96h更加明显（P〈0．01）；Cull基因干涉6h后2种细胞G，期细胞比例[（29．49±0．75）％、（24．86％±0．52）％]增加，与对照组[（17．39±0．56）％、（t2．73％±0．41）％]比较差异有统计学意义（P〈0．01）。Cull基因干涉后2种细胞CyclinA、CyclinD1及CyclinE表达明显减少，而p21和p27表达明显增加，差异均有统计学意义（P〈0．01）。结论Cull基因干涉后能通过影响细胞周期蛋白及其依赖性激酶抑制因子的表达，使乳腺癌细胞停滞在G1期，最终抑制其增殖。

英文摘要：

Objective To investigate the role of Cullinl （Cull） gene on human breast cancer cell proliferation. Methods The Cull small interfering RNA （siRNA） were transferred into MDA-MB-231 and BT-549 breast cancer cells. The expression of Cull gene in both cancer cells were assessed by Western blot- ting. The proliferation of both cancer cells after Cull interference were measured by cell counting kit-8 （ CCK-8 ） assay. The cell cycle of breast cancer cells were detected by flow cytometry. The expression levels of Cyclin family （Cyclin A, Cyclin D1, Cyclin E） and CDK inhibitor proteins （p21 and p27） were detec- ted by Western blotting. Results Cull siRNA could silence the expression of Cull gene in both breast cancer cells significantly. Cull interference could drastically decreased the ability of cell proliferation in both breast cancer cells and rose to its peak level at 96 h. The G1 population in both breast cancer cells treated by Cull siRNA [ （29. 49 _＋ 0.75 ） %, （ 24. 86 ＋ 0. 52 ） % ] increased significantly than the cells treated by control siRNA [ （ 17.39 ＋ 0. 56） %, （ !2. 73 ＋ 0.41 ） % ] at 6 h. The expression levels of Cyclin A, Cyclin D1, and Cyclin E proteins were drastically decreased in both breast cancer cells after Cull inter- ference, at the same time, p21 and p27 protein expression leve｜s was significantly increased. Conclusion Silence of Cull could suppress human breast cancer cell growth through down-regulation of Cyclin A, Cyc- lin D1, ancl Cyclin E proteins, up-regulation of p21 and p27 proteins making cell cycle arrest at G1 phase.