目的：探讨miR-21靶向程序性细胞死亡因子4（programmed cell death factor 4，PDCD4）对非小细胞肺癌（non-small cell lung cancer，NSCLC）A549 细胞增殖和迁移的影响及其作用机制。方法：采用脂质体转染技术分别将 miR-21 mimics、miR-21 inhibitors、miR-NC质粒转染到对数生长期的A549细胞，转染48 h后在荧光显微镜下观察转染效率，用qPCR法检测A549细胞中miR-21、PDCD4 mRNA的表达水平。用双荧光素酶报告基因验证miR-21与PDCD4的靶向关系，用MTT法检测细胞的增殖能力，用Transwell小室法检测细胞的迁移能力，用 ELISA 法检测各组细胞培养液中TNF-α水平，用WB法检测细胞中PDCD4、NF-κB p65、p-NF-κB p65蛋白的表达水平。结果：成功构建miR-21过表达和沉默的A549细胞系。双荧光素酶报告基因实验证实miR-21靶向抑制 PDCD4 表达。过表达 miR-21 可明显抑制A549细胞中PDCD4 mRNA表达（P<0.01），促进细胞的增殖与迁移能力（P<0.05 或 P<0.01），提高 TNF-α 分泌水平（P<0.01），下调 PDCD4 蛋白的表达（P<0.01），上调 p-NF-κB p65 蛋白的表达（P<0.05）。沉默miR-21对细胞的影响则与过表达miR-21的作用相反。结论：过表达miR-21可促进A549细胞增殖和迁移能力，该作用可能与其靶向抑制PDCD4、激活NF-κB/TNF-α通路有关。

Objective: To explore the effects of miR-21 targeting PDCD4 (programmed cell death factor 4) on proliferation and migration of non-small cell lung cancer (NSCLC) A549 cells and the possible mechanism. Methods: The miR-21 mimics, miR-21 inhibitors and miR-NC plasmids were transfected into A549 cells in logarithmic growth phase by liposome transfection technology. Forty-eight hours after transfection, the transfection efficiency was observed under a fluorescence microscope, and the mRNA expression levels of miR-21 and PDCD4 in A549 cells were detected by qPCR. Dual luciferase reporter gene experiment was used to detect the targeting relationship between miR-21 and PDCD4, MTT method was used to detect cell proliferation, Transwell chamber method was used to detect cell migration ability,and ELISA was used to detect the content of TNF-α in each group of cell culture fluids. WB was used to detect the protein expression levels of PDCD4, NF-κB p65 and p-NF-κB p65 in cells. Results: The A549 cell line with miR-21 over-expression or knockdown was successfully constructed. Dual luciferase reporter gene assay confirmed that miR-21 targetedly inhibited PDCD4 expression. Over-expression of miR-21 could significantly inhibit the mRNA expression of PDCD4 in A549 cells (P<0.01), promote cell proliferation and migration (P<0.05 or P<0.01), increase the secretion level of TNF-α (P<0.01), down-regulate the expression of PDCD4 protein (P<0.01), and up-regulate p-NF-κB p65 protein level (P<0.05). The effect of silencing miR-21 on cells was opposite to the effect of miR-21 over-expression.Conclusion: Over-expression of miR-21 can promote the proliferation and migration ability of A549 cells, which may be related to its targeted inhibition of PDCD4 and activating the NF-κB/TNF-α pathway.

河南省科技研发专项基金资助项目（No.172102310051）