目的：研究环状RNA nei 样DNA糖化酶3（circNEIL3）和微小RNA（miR）-4784 对乳腺癌细胞MDA-MB-231 的增殖、迁移和侵袭的影响。方法：收集2018 年1月至2019 年12月在济南市中西医结合医院经组织病理诊断为乳腺癌并行手术切除的45 例乳腺癌患者的癌组织和配对癌旁组织，qPCR 法检测乳腺癌组织、癌旁组织中circNEIL3 和miR-4784 的相对水平。将circNEIL3 的小干扰RNA（si-circNEIL3）、miR-4784 模拟物、si-circNEIL3+miR-4784 抑制物分别转染MDA-MB-231 细胞，采用CCK-8法、平板克隆实验、划痕愈合实验、Transwell 实验检测circNEIL3和miR-4784 表达对细胞活力、克隆形成、迁移和侵袭的影响。双荧光素酶报告基因实验、RNA免疫沉淀（RIP）和RNA pull-down 实验检测circNEIL3和miR-4784 之间相互作用。结果：乳腺癌组织中circNEIL3呈高表达（P<0.05），miR-4784 呈低表达（P<0.05）。干扰circNEIL3显著降低MDA-MB-231 细胞活力、克隆形成数、划痕愈合率以及侵袭数（均P<0.05）。过表达miR-4784 显著降低MDA-MB-231 细胞活力、克隆形成数、划痕愈合率以及侵袭数（均P<0.05）。双荧光素酶报告基因实验、RIP 和 RNA pull-down 实验均证实circNEIL3 与miR-4784 可直接结合，干扰circNEIL3 能明显上调miR-4784表达（P<0.05），过表达circNEIL3 能明显下调 miR-4784 表达（P<0.05）。抑制miR-4784 表达部分逆转干扰circNEIL3对MDA-MB-231 细胞活力、克隆形成、迁移和侵袭的抑制作用（P<0.05）。结论：干扰circNEIL3通过靶向上调miR-4784表达抑制MDA-MB-231细胞的增殖、迁移和侵袭。

Objective: To study the influence of circRNA nei-like DNA glucoamylase 3 (circNEIL3) and microRNA (miR)-4784 on the proliferation, migration, and invasion of breast cancer MDA-MB-231 cells. Methods: The cancer tissues and paired paracancerous tissues surgically removed from 45 breast cancer patients histopathologically diagnosed with breast cancer in Jinan Hospital of Integrated Traditional Chinese and Western Medicine from January 2018 to December 2019 were collected. qPCR were applied to measure the relative levels of circNEIL3 and miR-4784 in breast cancer tissues and paracancerous tissues. circNEIL3 small interfering RNA (si-circNEIL3), miR-4784 mimics, and si-circNEIL3+miR-4784 inhibitors were transfected into MDA-MB-231 breast cancer cells, respectively. CCK-8 assay, plate cloning assay, scratch healing assay, and Transwell assay were performed to detect the effects of circNEIL3 and miR-4784 expressions on the cell viability, clone formation, migration and invasion. Dual-luciferase reporter assay, RNA immunoprecipitation (RIP), and RNA pull-down assay were used to detect the interactions between circNEIL3 and miR-4784. Results: The relative level of circNEIL3 in breast cancer tissues was significantly higher than that in adjacent tissues (P<0.05) while the relative level of miR-4784 was significantly lower than that in adjacent tissues (P<0.05). Interference with circNEIL3 significantly reduced the viability, clonal formation numbers, wound healing rate, and invasion numbers of MDA-MB-231 cells (P< 0.05). Overexpression of miR-4784 significantly reduced the viability, clonal formation numbers, wound healing rate, and invasion numbers of MDA-MB-231 cells (P<0.05). Dual luciferase reporter gene assay, RIP, and RNA pull-down assay confirmed that circNEIL3 directly binds to miR-4784. Interference with circNEIL3 significantly up-regulated miR-4784 expression (P<0.05), and overexpression of circNEIL3 significantly down-regulated miR-4784 expression (P<0.05). miR-4784 inhibition partially reversed the inhibitory effect of interference with circNEIL3 on the viability, colony formation, migration, and invasion of MDA-MB-231 cells (P<0.05). Conclusion: Interference with circNEIL3 inhibits the proliferation, migration, and invasion of breast cancer cells by targeting and up-regulating miR-4784 expression.