RESUMEN
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.