中文摘要：

目的：探讨长链非编码RNA MEG3在胃癌组织及细胞系中的表达水平,以及过表达MEG3对胃癌细胞增殖能力的影响,并探索其可能的作用机制。方法：用定量反转录PCR（qRT-PCR）技术检测胃癌组织及细胞系中MEG3的表达水平;通过转染pcDNA-MEG3上调MEG3的表达水平,并通过qRT-PCR检测转染效率。用MTT和克隆形成试验检测上调MEG3的水平对BGC-823细胞和MGC-803细胞的增殖能力的影响,Western blot检测这两种细胞中上调MEG3的水平对p53蛋白的表达水平的影响。结果：相比正常胃组织及细胞,在胃癌组织和细胞中MEG3的表达出现显著下调,SGC7901。MGC-803和BGC-823细胞中MEG3的表达水平分别是正常胃上皮细胞GES-1中的73.6%。42.0%和27.1%（P 〈 0.05）。BGC-823细胞和MGC-803细胞中转染pcDNA-MEG3能显著上调MEG3的表达,MEG3的表达水平分别为对照组的252倍和311倍（P 〈 0.05）;MTT和克隆形成试验显示,上调MEG3的表达能降低BGC-823细胞和MGC-803细胞的增殖能力。Western blot实验显示,转染了pcDNA-MEG3的MGC-803和BGC-823细胞中p53的表达相较对照组中显著增加。结论：胃癌组织及细胞中MEG3的表达下调,且这可能通过抑制p53蛋白的激活从而促进胃癌细胞增殖,影响胃癌的发生和发展。

英文摘要：

Objective：To investigate the expression level of long noncoding RNA MEG3 in gastric cancer tissues and cell lines,and to study the effect of up-regulation of MEG3 expression on gastric cancer cells proliferation and its possible mechanisms. Methods：Quantitative reverse-transcription PCR was performed to detect the relative expression of MEG3 in gastric cancer cell lines and tissues. pcDNA-MEG3 was transfected into BGC-823 cells and MGC-803 cells to down-regulate MEG3 expression,and quantitative reverse-transcription PCR was used to test the transfection efficiency. MTT and colony formation assays were performed to detect the effect of MEG3 on gastric cancer cells proliferation. Western blot assay was used to test the expression level of p53 protein in MGC-803 cells and BGC-823 cells transfected with pcDNA-MEG3,respectively. Results：This study showed that MEG3 was lowly expressed both in gastric cancer samples and cell lines compared with their corresponding normal tissues and cell lines. The expression level of MEG3 in SGC7901,MGC-803 and BGC-823 cells were 73.6%,42.0% and 27.1% of that in normal gastric epithelium cell GES-1,respectively（P 〈 0.05）. Transfection of pcDNA-MEG3 significantly increased its expression in BGC-823 cells and MGC-803 cells,respectively,252 and 311 folds compared with control cells（P 〈 0.05）. MTT and colony formation assays indicated that up-regulated MEG3 inhibited BGC-823 and MGC-803 cells proliferation. Western blot assay showed that the expression level of p53 protein was significantly increased in MGC-803 cells and BGC-823 cells transfected with pcDNA-MEG3, compared with the control group,respectively. Conclusion：Down-regulated MEG3 could promote gastric cells proliferation,probably by inhibiting the activation of p53 protein,and thus affect the development and progression of gastric cancer.