miR-21靶向E2F1对三阴性乳腺癌细胞恶性生物学活性及裸鼠肿瘤抑制率的影响

目的 探究miR-21靶向E2F1对三阴性乳腺癌细胞恶性生物学活性及裸鼠肿瘤抑制率的影响。方法将MDA-MB-231细胞分为5组，即MDA-MB-231组、miR-21 inhibitor组、miR-NC inhibitor组、siRNA-E2F1组和siRNA-NC组。检测细胞中miR-21表达（RT-PCR法）；分别检测细胞增殖（MTT法）、侵袭（Transwell法）、迁移（划痕实验）和凋亡能力（流式细胞仪）；检测细胞中E2F1蛋白表达；检测miR-21与E2F1的靶向关系（双荧光素酶实验报告）。结果MDA-MB-231细胞中miR-21表达明显高于MCF10A细胞（P<0.05）；miR-21 inhibitor组细胞细胞中miR-21表达明显低于MDA-MB-231组（P<0.05）。与MDA-MB-231组相比，miR-21 inhibitor组细胞吸光度值、侵袭能力、迁移能力和细胞中E2F1蛋白表达均明显降低，细胞凋亡能力明显升高（P<0.05）；MDA-MB-231组细胞吸光度值、侵袭、迁移、凋亡能力和细胞中E2F1蛋白表达与miR-NC inhibitor组相比差异无统计学意义（P>0.05）。预测软件显示E2F1的3′UTR端与miR-21有碱基互补结合点位。通过向MDA-MB-231细胞中转染野生型E2F1（E2F1-WT）时，miR-21组荧光素酶活性明显低于miR-NC组（P<0.05）；miR-21组和miR-NC组突变体荧光素酶活性相比差异无统计学意义（P>0.05）。与siRNA-NC组相比，siRNA-E2F1组细胞增殖、侵袭、迁移和细胞中E2F1蛋白表达均明显降低，细胞凋亡能力明显增加（P<0.05）。与miR-NC inhibitor组裸鼠移植肿瘤第8天时相比，miR-21 inhibitor组裸鼠肿瘤体积明显降低，肿瘤抑制率为45.3%（P<0.05）。结论低表达miR-21可抑制三阴性乳腺癌细胞增殖、侵袭，促进凋亡，且抑制裸鼠移植瘤体积，其作用机制可能与抑制E2F1表达有关。

Effects of miR-21 targeting E2F1 on malignant biological activity of triple-negative breast cancer cells and its tumor inhibition rate in nude mice

Objective To investigatethe effect of miR-21 targeting E2F1 on the malignant biological activity of triple-negative breast cancer cells and its tumor inhibition rate in nude mice. Methods The MDA-MB-231 cells were divided into 5 groups, including MDA-MB-231 group, miR-21 inhibitor group, miR-NC inhibitor group, siRNA-E2F1 group and siRNA-NC group. Th miR-21 expression in cells was assessed with RT-PCR method.The cell proliferation, invasion, migration and apoptosiswere assessed with MTT method, transwell method, scratch test and flow cytometry, respectively. The protein expression of E2F1 in cells was assessed.The targeting correlation between miR-21 and E2F1 was assessed dual-luciferase experimental report. Results The expression of miR-21 in MDA-MB-231 cells was significantly higher than that in MCF10A cells (P<0.05).The expression of miR-21 in miR-21 inhibitor group cells was significantly lower than that in MDA-MB-231 group (P<0.05). Compared with the MDA-MB-231 group, the absorbance, invasion ability, migration ability and E2F1 protein expression in the cells of the miR-21 inhibitor group were significantly reduced, while the apoptosis ability was significantly increased (P<0.05). Compared with the miR-NC inhibitor group, there was no significant differences in the absorbance, invasion, migration, apoptosis ability or E2F1 protein expression in the MDA-MB-231 group (P>0.05). The prediction software showed that the 3′UTR end of E2F1 had a base complementary binding site to miR-21. By transfecting wild-type E2F1 (E2F1-WT) into MDA-MB-231 cells, the luciferase activity of miR-21 group was significantly lower than that of miR-NC group (P<0.05). There was no significant difference in luciferase activity between miR-21 group and miR-NC group (P>0.05). Compared with the siRNA-NC group, the cell proliferation, invasion, migration and E2F1 protein expression in the siRNA-E2F1 group were significantly reduced, and the apoptosis ability was significantly increased (P<0.05). Compared with the miR-NC inhibitor group on the 8th day of tumor transplantation, the tumor volume of the miR-21 inhibitor group was significantly reduced, and the tumor inhibition rate was 45.3% (P<0.05). Conclusion Low expression of miR-21 can inhibit the proliferation and invasion of triple-negative breast cancer cells, promote apoptosis, and inhibit the volume of transplanted tumors in nude mice, and its mechanism may be related to the inhibition of E2F1 expression.