探讨S-腺苷甲硫氨酸抑制miRNA-34a依赖的肺癌转移机制。

选取肺癌细胞A549，分别采用0、50、100、200、500 μM的S-腺苷甲硫氨酸(S-adenosylmethionine, SAMe)刺激A549细胞并检测miR-34a以及下游STAT3信号通路的表达情况，同时检测不同刺激条件下A549细胞的侵袭转移情况；实时荧光定量(real-time fluorescence quantification, qPCR)检测miR-34a、E-cadherin、α-catenin、N-cadherin、Vimentin的mRNA表达水平；Western Blot实验检测STAT3、p-STAT3、β-actin的表达水平；Transwell实验检测A549细胞的侵袭能力变化。

随着SAMe浓度的增加，miR-34a的表达水平呈梯度增加，与对照组相比，经t检验分析，差异有统计学的意义(P<0.05)；Western Blot实验显示，与对照组相比，500 μM SAMe刺激后，下游的p-STAT3蛋白水平下降，总STAT3和内参蛋白β-actin水平不变；qPCR结果显示，随着药物浓度的增加，表皮蛋白E-cadherin、α-catenin的mRNA水平上升，间质蛋白N-cadherin、Vimentin的mRNA水平下降；Transwell实验显示经50、100、200、500 μM的SAMe刺激后，A549细胞的侵袭转移抑制率分别为18.70%、31.24%、47.66%、58.46%，与对照组相比，经t检验分析，差异有统计学的意义(P<0.05)。

SAMe可通过抑制miR-34a依赖的下游STAT3信号通路抑制肺癌细胞的侵袭转移，提示SAMe在肺癌侵袭转移过程中发挥重要作用。

To investigate the molecular mechanisms of S-adenosine methionine in suppressing lung cancer metastasis with a miRNA-34a-dependent manner.

A549 lung cancer cell was selected as the study model of this time research. A549 cells were stimulated with 0, 50, 100, 200, 500 μM SAMe, respectively and the expression of miR-34a and its related STAT3 signaling pathways were also detected. The invasive capacity of cells was detected under various condition as well; miR-34a, E-cadherin, α-catenin, N-cadherin and Vimentin mRNA expression were detected by qPCR method; Western Blot was used to detect expression of STAT3, p-STAT3 and β-actin; Invasive capacity of A549 cells was detected by Transwell experiment.

As the increase of SAMe concentration, miR-34a expression increased gradually, and when it was compared to the control group, the difference was statistically significant through the t-test (P<0.05); Western Blot experiments showed that p-STAT3 protein level of 500 μM SAMe stimulation was lower than 0 μM treatment, while total STAT3 and β-actin level had no change; q-PCR results showed that E-cadherin and α-catenin level elevated, but N-cadherin and Vimentin level decreased as the increase of drug concentration; Transwell experiments showed that invasive inhibitory rates of A549 cells in 50, 100, 200, 500 μM of SAMe were 18.70%, 31.24%, 47.66% and 58.46%, respectively. And compared to the control group, the difference had statistical significance by t-tset (P<0.05).

SAMe could suppress cell metastasis through a miR-34a-dependent manner by inhibiting STAT3 signaling pathway in lung cancer cells, which suggested a potential role of SAMe in metastasis of lung cancer.