miR-340通过靶向GRP78促进结直肠癌细胞凋亡并抑制其增殖、迁移和侵袭

miR-340能够促进癌细胞的增殖和侵袭，但是在结直肠癌中miR-340如何调控癌症的发生与发展鲜有报道。本研究探究miR-340在结直肠癌细胞中的生物学功能和靶基因调控机制。首先通过RT-qPCR检测不同的结直肠癌细胞株中miR-340的表达水平，再利用过表达和抑制miR-340，分别转染COLO-205细胞，以CCK-8检测细胞的增殖能力，Transwell法检测细胞的迁移和侵袭能力，流式细胞技术检测细胞的凋亡和细胞周期分布；最后通过生物信息学预测miR-340的靶基因，荧光素酶报告基因及Western印迹分析进行验证。结果显示，miR-340在COLO-205细胞中低表达，与对照组比较，细胞的增殖、迁移和侵袭在过表达miR-340转染组显著受到抑制，在抑制miR-340组中却被促进（P<0.01）。流式细胞检测结果显示，过表达miR-340 转染组细胞凋亡比例显著升高，而抑制miR-340 组中凋亡比例却降低（P<0.01）。过表达miR-340 转染组细胞生物信息学分析结果显示，葡萄糖调节蛋白78（glucose regulated protein 78 kD, GRP78）的3′UTR上有miR-340-5p的结合位点，并且荧光素酶活性在转染过表达miR-340 组中显著降低（P<0.01）；Western 印迹结果同样表明，过表达miR-340能够抑制GRP78的表达，而抑制miR-340，GRP78的表达抑制解除。综上所述，miR-340能够直接靶向GRP78来促进COLO-205细胞的凋亡，并抑制其增殖、迁移和侵袭。

The Biological Role of miR-340 in Colorectal Cancer Cells and the Regulatory Mechanism of Target Genes

miR-340 can promote the proliferation and invasion of cancer cells, but how miR-340 regulates the occurrence and development of cancer in colon cancer is rarely reported. This study aims to explore the biological function and target gene regulation mechanism of miR-340 in colorectal cancer cells. Firstly, RT-qPCR was used to detect the expression level of miR-340 in different colorectal cancer cell lines, and then miR-340 was overexpressed or inhibited in COLO-205 cells. CCK-8, Transwell migration and invasion assay, and flow cytometry were performed to analyze the cell ability of proliferation, migration and invasion, as well as cell apoptosis and cell cycle. Finally, after bioinformatics prediction of miR-340 target genes, luciferase reporter gene and Western blot experiment were applied to verify those target genes. The results showed that miR-340 was downregulated in COLO-205 cells. Compared with the control group, cell proliferation, migration and invasion were significantly inhibited in the miR-340 overexpression group, but were promoted in the miR-340 suppression group (P<0.01). The results of flow cytometry showed that the percentage of apoptosis in the miR-340 overexpression group was significantly increased, while the percentage of apoptosis in the miR-340 inhibition group was decreased (P<0.01). The bioinformatics analysis of the overexpression miR-340 transfection group showed that the 3′UTR of glucose regulated protein 78 kD (GRP78) had a miR-340-5p binding site, and the luciferase activity was significantly reduced in the overexpression miR-340 group (P<0.01); Western blot results also showed that overexpression of miR-340 can inhibit the expression of GRP78, while inhibiting miR-340 expression, the expression of GRP78 is relieved. In summary, miR-340 can directly target GRP78 to promote the apoptosis of COLO 205 cells and inhibit their proliferation, migration and invasion.