中文摘要：

目的：采用RNA干扰技术下调Notch2基因在Lewis肺癌细胞（LLC）的表达,探讨Notch2表达下调对LLC增殖和周期的影响。方法：通过脂质体2000将Notch2-siRNA和对照con-siRNA分别转染LLC后,通过PCR,RT-PCR检测Notch2的表达情况;通过MTT、软琼脂克隆形成实验检测LLC的生长情况;并使用流式细胞技术检测细胞周期。结果：SiRNA转染LLC48小时后,PCR和RT-PCR检测结果显示Notch2在实验组的表达受到显著抑制;MTT实验显示干扰Notch2的表达显著抑制了LLC的增殖（P〈0.001）;软琼脂克隆形成实验表明干扰Notch2的表达将影响LLC的克隆形成;细胞周期实验进一步证实干扰Notch2的表达使处于活跃增殖期（S期）的LLC数量明显减少。结论：Notch2在LLC中的表达发挥重要的促癌作用,干扰Notch2的表达能显著抑制LLC的分裂增殖和克隆形成,从而抑制肿瘤的生长。

英文摘要：

Objective：To investigate the effects of Lewis lung cancer cells（LLC） after Notch2 gene down-regulated by siRNA on cell circle and proliferation.Methods：Notch2-siRNA and control siRNA（con-siRNA） were transfected into LLC respectively by lipofectamin 2000.Notch2 mRNA expression was detected by PCR and real-time PCR after 48 hours;MTT and soft agar colony assays were performed to examine cell proliferation.Cell cycle was analyzed by flow cytometry.Results：The expression of Notch2 mRNA in LLC reduced significantly in Notch2-siRNA groups（P0.001） after 48 h transfection.The results of MTT showed that down-regulation of Notch2 expression inhibited LLC proliferation（P0.001）.Clone formation of LLC was also inhibited after Notch2-siRNA transfection.In addition,down-regulation of Notch2 expression significantly decreased the number of LLC in S phase of cell cycle.Conclusion：Notch2 gene functions play as an oncogene in LLC.Down-regulation of Notch2 expression by siRNA inhibits LLC proliferation and clone formation in vitro.