Background and objective: Recent studies suggest that miR-155 is involved in lung tumorgenesis, whereas the precise mechanism has not yet been characterized. The aim of this study is to investigate the effects of over-expression of miR-155 on the growth of human lung cancer 95D cells in vitro and its possible mechanism, and thus to provide experimental evidence for further researching on the role of miR-155 in the pathogenesis and development of lung cancer.
Methods: miR-155 mimics control and miR-155 mimics were tranfected into human lung cancer 95D cells by FuGENE®HD Transfection Reagent respectively in vitro. The relative expression level of miR-155 in 95D cells was determined using specific probe of real-time PCR after transfection. The proliferation of 95D cells was detected by MTT assay. The cell cycle was analyzed by flow cytometry. The expression of SOS1 protein was measured by Western blot.
Results: Compared with control groups, the expression level of miR-155 was significantly increased in miR-155 mimics transfected group (P<0.05). The proliferation of miR-155-transfected 95D cells was significantly inhibited (P<0.05). The percentage of G0/G1 phase cells was increased significantly in miR-155-transfected 95D cells, while the percentage of S phase was remarkably reduced (P<0.05). Furthermore, the expression of SOS1 in miR-155-transfected 95D cells was significantly down-regulated (P<0.05).
Conclusions: miR-155 could significantly inhibit the growth of human lung cancer 95D cells in vitro, which might be closely related to miR-155 induced G0/G1 phase arrest.
背景与目的: 近年来的研究发现miRNAs（microRNAs）家族成员miR-155与肺癌的发生相关，然而具体机制不明。本研究拟探讨上调miR-155表达对人肺癌95D细胞体外生长的影响及其可能的作用机制，为后续深入研究miR-155在肺癌发生、发展中的作用提供新的实验依据。
方法: 人肺癌95D细胞分为空白对照组、miR-155阴性对照组和miR-155转染组，分别作加入转染试剂、转染miR-155阴性对照和转染miR-155处理。Real-time PCR特异性探针法检测转染后95D细胞中miR-155的表达水平；应用MTT法检测miR-155对95D细胞增殖的抑制作用；流式细胞术检测95D细胞周期的分布；Western blot检测95D细胞SOS1蛋白的表达变化。
结果: Real-time PCR结果显示，与对照组相比，转染组95D细胞miR-155的表达水平明显增加（P < 0.05）；镜下可见转染miR-155的95D细胞生长减缓，形态发生改变；MT结果表明miR-155转染后，95D细胞增殖受到抑制，转染组和对照组存在明显差异（P < 0.05）；流式细胞术分析显示，与对照组相比，转染miR-155的95D细胞周期发生改变，G0/G1期细胞明显增多，而S期则明显减少（P < 0.05）；Western blot结果显示转染组95D细胞SOS1蛋白的表达明显降低（P < 0.05）。
结论: miR-155能明显抑制人肺癌95D细胞的体外生长，这可能与miR-155下调SOS1表达及诱导95D细胞G0/G1期阻滞相关。