目的：探讨miR-455-3p在胃癌细胞中的表达及对胃癌细胞增殖和凋亡的影响。方法：用qRT-PCR检测miR-455-3p在正常胃黏膜上皮细胞RGM-1及5种胃癌细胞系（AGS、Hs746T、MGC-803、SGC-7901及BSG-823）中的表达。将胃癌细胞miR-455-3p模拟物后，分别用CCK8法检测细胞增殖，流式细胞术检测细胞凋亡，Western blot检测细胞p27 kip1、p21的蛋白表达，分光光度法检测细胞caspase酶活性。结果：miR-455-3p在5种胃癌细胞系中的表达水平明显低于RGM-1细胞系，其中在AGS细胞中降低最为明显（均P<0.05）。AGS细胞转染miR-455-3p模拟物后，增殖能力明显降低而胞凋亡率明显升高，p27 kip1蛋白表达量明显升高，caspase-3与caspase-9相对活性明显升高（均P<0.05），但p21蛋白表达量与caspase-8相对活性无明显改变（均P>0.05）。结论：miR-455-3p在胃癌细胞表达下调，增加其表达可抑制胃癌细胞增殖并促进凋亡，其机制可能与其上调p27 kip1表达及增强caspase-3、caspase-9活性有关。
MiR-455-3p expression and its action on proliferation and apoptosis in gastric carcinoma cells
Objective: To investigate the miRNA-455-3p expression and its action on proliferation and apoptosis in gastric cancer cells. Methods: The miRNA-455-3p expression levels in normal gastric mucous cell line RGM-1 and five different types of gastric cancer cell lines (AGS, Hs746T, MGC-803, SGC-7901 and BSG-823) were determined by qRT-PCR method. In gastric cancer cells after transfection with miRNA-455-3p mimics, the cell proliferation was measured by CCK8 assay, the apoptosis was assayed by flow cytometry, the expressions of p27 kip1 and p21 were determined by Western blot analysis, and the activities of the caspase enzymes were analyzed by spectrophotometric method, respectively. Results: The miR-455-3p expression levels were significantly decreased in all the five types of gastric cancer cells compared with RGM-1 cells, which was most evident in AGS cells (all P<0.05). in AGS cells after transfection with miR-455-3p mimics, the proliferative ability was decreased, the apoptosis rate was increased, the p27 kip1 protein expression level was up-regulated, and the relative activities of caspase-3 and -9 were increased significantly (all P<0.05), while the p21 protein expression level and caspase-8 activity showed no significant changes (both P>0.05). Conclusion: miRNA-455-3p expression is down-regulated in gastric cancer cells, up-regulating its expression can inhibit proliferation and induce apoptosis in gastric cancer cells and the mechanism may be associated with its increasing p27 kip1 expression and enhancing caspase-3 and -9 activities.