[摘要] 目的：探讨miR-424/高迁移率蛋白A1 基因（nigh mobility protein A1，HMGA1）分子轴对乳腺癌细胞放疗敏感性的影响及其分子机制。方法：收集2014 年4 月至2017 年4 月无锡市第四人民医院肿瘤放疗科经手术切除的50 例乳腺癌患者的癌组织标本，用qPCR和Western blotting 检测miR-424 和HMGA1 mRNA与蛋白在乳腺癌放疗敏感患者和放疗抵抗患者癌组织中的表达水平。用不同辐射强度（0、2、4、6 和8 Gy）的60Co γ - 射线处理人乳腺癌细胞株MDA-MB-468 后，观察细胞miR-424 和HMGA1 的表达变化。向MDA-MB-468 细胞中转染miR-424 mimic/inhibitor 和pcDNA-HMGA1，采用平板克隆形成实验、MTT法、Transwell 小室法和Annexin V-FITC/PI 染色流式细胞术检测miR-424 对辐射处理后乳腺癌细胞增殖、侵袭和凋亡的影响。用双荧光素酶报告基因验证miR-424 与HMGA1 的靶向关系。结果：与放疗抵抗的乳腺癌患者比较，miR-424 在放疗敏感的乳腺癌患者癌组织中高表达（P<0.01），HMGA1 低表达（P<0.01）。与0、2 和4 Gy 处理组细胞比较，6 和8 Gy 的γ-射线处理后乳腺癌MDA-MB-468 细胞凋亡率和miR-424 的表达水平显著升高（均P<0.01）；细胞的侵袭能力和HMGA1 的表达水平显著降低（均P<0.01）。双荧光素酶报告基因证实miR-424 靶向作用HMGA1 并下调其表达水平。miR-424 通过靶向下调HMGA1 显著抑制MDA-MB-468 细胞的增殖、侵袭并促进细胞凋亡（均P<0.01），进而上调MDA-MB-468 细胞对放疗的敏感性。结论：miR-424/HMGA1 分子轴可调控乳腺癌放疗敏感性，过表达miR-424 可增强乳腺癌MDA-MB-468 细胞对γ-射线放疗的敏感性。

[Abstract] Objective: To explore the effect of miR-424/HMGA1 (high mobility protein A1) axis on the radio-sensitivity of breast cancer cells and the possible mechanism. Methods: A total of 50 cases of breast cancer tissues from patients, who underwent surgical resection at the Department of Oncological Radiotherapy, Wuxi Fourth People’s Hospital from April 2014 to April 2017, were collected for this study. Real-time quantitative polymerase chain reaction (qPCR) and Western blotting were performed to evaluate the mRNA and protein expressions of miR-424 and HMGA1 in breast cancer tissues of radiation sensitive and insensitive patients. After being treated with different doses of 60Co γ - ray radiation (0, 2, 4, 6 and 8 Gy), the expression changes of miR-424 and HMGA1 in breast cancer MDA-MB-468 cells were observed. Subsequently, miR-424 mimic/inhibitor and pcDNA-HMGA1 were transfected into MDA-MB-468 cells, and the effect of miR-424 on cell proliferation, invasion and apoptosis of radiation-treated MDA-MB-468 cells were evaluated by colony formation assay, MTT assay, Transwell assay and Annexin V-FITC/PI double staining flow cytometry assay, respectively. Furthermore,dual luciferase reporter gene assay was used to verify whether HMGA1 was a target gene of miR-424. Results: The patients in radio-sensitive group exhibited higher miR-424 expression but lower HMGA1 expression than the patients in insensitive group (all P<0.01). Compared with the cells treated with 0, 2 and 4 Gy radiation, the cells treated with 6 and 8Gy radiation exhibited significantly higher apoptosis rate and miR-424 expression but lower HMGA1 expression and cell invasion (all P<0.01). Moreover, luciferase reporter gene assay confirmed that miR-424 down-regulated HMGA1 expression. Mechanistically, miR-424 significantly inhibited cell proliferation, invasion and induced apoptosis of MDA-MB-468 cells (all P<0.01) via targeted down-regulating HMGA1, and further upregulated the radio-sensitivity of breast cancer cells. Conclusion: miR-424/HMGA1 axis regulates the radio-sensitivity of breast cancer,and over-expression of miR-424 may increase the sensitivity of MDA-MB-468 cells to γ-ray radiation therapy.