目的：探讨miR-125a-5p 在诱导非小细胞肺癌（non-small cell lung cancer，NSCLC）细胞吉非替尼（gefitinib，Gef）耐药中的作用及其机制。方法：选用人NSCLC 耐药细胞株A549/GR 和NSCLC细胞株A549，将miR-125a-5p mimic、miR-125a-5p inhibitor、pcDNA3.1-APAF1、空载体pcDNA3.1 转染至A549/GR细胞。用qPCR检测细胞中miR-125a-5p 的表达水平，用MTT法、Transwell 小室法和流式细胞术检测Gef 对细胞增殖、迁移和凋亡的影响。用双荧光素酶报告基因实验验证miR-125a-5p 与细胞凋亡蛋白酶活化因子1（apoptotic peptidase activating factor 1，APAF1）的靶向关系，用Western blotting检测A549/GR细胞中APAF1蛋白水平，用比色法测定细胞中caspase-3 及caspase-9 表达水平。结果：A549/GR 细胞中miR-125a-5p 表达水平显著高于A549 细胞（P<0.01）。敲降miR-125a-5p 显著增强Gef 对A549/GR细胞增殖、迁移的抑制作用（均P<0.05），并促进细胞凋亡（P<0.01）。双荧光素酶报告基因实验证实miR-125a-5p 靶向APAF1，并负调控其表达。进一步实验显示，miR-125a-5p 通过靶向下调APAF1 缓解Gef 对A549/G 细胞增殖、迁移的抑制作用及凋亡的促进作用（均P<0.05），减弱Gef引起的凋亡相关蛋白caspase-3及caspase-9表达的上调（均P<0.05）。结论：miR-125a-5p 促进NSCLC细胞Gef 耐药，其机制是通过靶向APAF1 而促进细胞的增殖、迁移并抑制凋亡。

Objective: To investigate the role of miR-125a-5p in inducing the gefitinib (Gef)-resistance of non-small cell lung carcinoma (NSCLC) cells and its possible mechanism. Methods: Human NSCLC drug-resistant cell line A549/GR and NSCLC cell line A549 were chosen for this study. miR-125a-5p mimic, miR-125a-5p inhibitor, pcDNA3.1-APAF1 and empty vector pcDNA3.1 were transfected into A549/GR cells. The expression level of miR-125a-5p in cell lines was detected by qPCR. MTT, Transwell and Flow cytometry were used to detect the effects of Gef on proliferation, migration and apoptosis of cell lines, respectively. The targeting relationship between miR-125a-5p and APAF1 (apoptotic peptidase activating factor 1) was verified by Dual-luciferase reporter gene system. In addition, the expression of APAF1 protein in A549/GR cells was detected by Western blotting. The expression levels of caspase-3 and caspase-9 were assessed by colorimetry. Results: Expression level of miR-125a-5p was upregulated significantly in Gefresistant A549/GR cells (P<0.01). And the influences of Gef onA549/GR cells were enhanced by knockdown of miR-125a-5p, including inhibiting cell proliferation and migration (all P<0.05) and inducing apoptosis (P<0.01). Dual luciferase reporter gene assay confirmed that miR-125a-5p targeted APAF1 and negatively regulated its expression. Furthermore, by targetedly downregulating APAF1,miR-125a-5p alleviated the inhibition of proliferation and migration (all P<0.05) and promotion of apoptosis (P<0.05) of A549/GR cells caused by Gef, and attenuated Gef-induced upregulation of apoptosis-related proteins caspase-3 and caspase-9 (all P<0.05).Conclusion: miR-125a-5p promotes Gef-resistance of A549/GR cells, and the underlying mechanisms are promotion of proliferation,migration and inhibition of apoptosis of non-small cell lung cancer cells by targeting APAF1.