miR-27b-3p通过靶向PLK2促进乳腺癌细胞的辐射抵抗

目的 研究miR-27b-3p对乳腺癌细胞辐射抵抗的影响。方法 通过检索基因表达（GEO）数据库，筛选分析miR-27b-3p在正常乳腺组织和乳腺癌组织中的表达水平。利用实时荧光定量PCR技术分析其在不同乳腺癌细胞系中的表达水平。通过细胞克隆形成、免疫荧光和5-乙炔基-2''-脱氧尿苷（EDU）检测技术评价miR-27b-3p对乳腺癌细胞辐射抵抗作用。采用荧光素酶报告基因技术确定miR-27b-3p的靶基因PLK2，并在乳腺癌细胞中进一步验证miR-27b-3p的辐射抵抗作用。结果 与正常乳腺组织和细胞相比，miR-27b-3p在乳腺癌组织（t=2.99，P<0.01）和乳腺癌细胞中表达水平显著上调（t=21.21、32.88，P<0.05）。尤其在抗辐射细胞MCF-7R中升高更加明显（t=25.63，P<0.05）。过表达miR-27b-3p增强了MCF-7细胞的克隆形成能力（t=10.32，P<0.05），且随着辐照剂量的增加，miR-27b-3p对MCF-7增殖能力的保护效应逐渐凸显（t=8.77、8.26、8.03，P<0.05）；干扰miR-27b-3p则抑制MCF-7R细胞克隆形成数（t=40.00，P<0.05），且随着辐照剂量的增加，进一步削弱了MCF-7R细胞的增殖能力（t=8.54、8.32、8.23，P<0.05）。报告基因实验结果表明，PLK2是miR-27b-3p的直接靶标。过表达PLK2抑制了miR-27b-3p介导的乳腺癌细胞辐射抵抗（MCF-7：t=9.66，P<0.05；MCF-7R：t=6.42，P<0.05）。结论 miR-27b-3p可通过靶向PLK2提高乳腺癌细胞的辐射抗性。

Elevated miR-27b-3p enhances the radioresistance by targeting PLK2 in breast cancer

Objective To investigate the effect of miR-27b-3p on radiation resistance of breast cancer cells.Methods The relative expression levels of miR-27b-3p in normal tissues and breast cancer tissues were analyzed through GEO database and verified by the qRT-PCR assay. Cloning formation, immunofluorescence, and EDU assay were used to assess the functions of miR-27b-3p on radioresistance of breast cancer cells. The luciferase reporter assay was used to verify whether miR-27b-3p directly targeted PLK2 mRNA. A rescue experiment was performed to identify the influence of PLK2 overexpression on miR-27b-3p regulated radioresistance.Results The expression level of miR-27b-3p in both breast cancer tissues (t=2.99, P<0.01) and breast cancer cells (t=21.21, 32.88, P<0.05) was significantly higher than those in normal breast tissues and cells, especially, it was elevated in radioresistant MCF-7R cells (t=25.63, P<0.05). Overexpression of miR-27b-3p enhanced the cloning efficiency of MCF-7 cells (t=10.32, P<0.05), and had a protective effect on the proliferation of irradiated MCF-7 cells (t=8.77, 8.26, 8.03, P<0.05). But interference of miR-27b-3p reduced the cloning efficiency and proliferation of MCF-7R cells (t=40.00, P<0.05) after irradiation with different doses(t=8.54, 8.32, 8.23, P<0.05). Moreover, PLK2 was verified to be a direct target of miR-27b-3p, and overexpression of PLK2 inhibited miR-27b-3p-mediated radioresistance of breast cancer cells (MCF-7:t=9.66, P<0.05; MCF-7R:t=6.42, P<0.05).Conclusions miR-27b-3p contributes to the radioresistance of breast cancer cells by targeting PLK2.