ABSTRACT
Objective: To observe the influence of miRNA-21 in the radiosensitivity of the breast cancer cells, and to preliminarily explore its mechanism. Methods: The breast cancer T47D and MDA-MB-361 cells were irradiated with 0. 0. 2.5. and 5. 0 Gy y-ray. respectively; CCK8 assay was used to detect the survival rates of T47D and MDA-MB-361 cells and flow cytometry was used to analyze the cell cycle; real-time quantitative PCR was used to detect the expression levels of miRNA-21 in cells during 72 h. The T47D and MDA-MB-361 cells were transfected with anti-miRNA-21 sequence (anti-miRNA-21 group) and negative control sequence (negative control group)∗ respectively; the untransfected cells were set as blank control group. Real-time quantitative PCR was used to detect the expression levels of miRNA-21 in cells in various groups. After irradiation with 0. 0 and 5. 0 Gy y-ray. CCK8 assay was used to detect the survival rates, and flow cytometry was used to analyze the cell cycle. Results: After irradiation with 5. 0 Gy y-ray. the survival rate of T47D cells was significantly higher than that of the MDA-MB-361 cells (PC0.05). Compared with 0. 0 Gy radiation group, the percentages of T47D and MDA-MB-361 cells in G: