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目的:研究MicroRNA-21与乳腺癌细胞MDA-MB-231放射敏感性之间关系及其表达规律。方法:①对乳腺癌细胞MDA-MB-231分别转染miR-21 mimics、miR-21 mimics Scramble(阴性对照)、miR-21 inhibitor、miR-21 inhibitorScramble(阴性对照),转染后进行集落形成实验,通过存活分数(Surviving Fraction SF)的变化检测其辐射敏感性是否发生变化;②时程实验:3Gy X-Ray照射后,分别于0、4、8、12、24 h后,实时荧光定量PCR检测miR-21的表达;③量效实验:0、1、2、4、6Gy X-Ray分别照射细胞24 h后,实时荧光定量PCR检测miR-21的表达。结果:MDA-MB-231细胞转染miR-21mimics后,SF明显升高,与正常对照组比较有显著性差异(P<0.05);MDA-MB-231细胞转染miR-21 inhibitor后,SF明显降低,与正常对照组比较有显著性差异(P<0.05);3GyX射线照射乳腺癌细胞株MDA-MB-231后,miR-21表达量上调,与对照组比较差异具有显著性(P<0.05),并在12 h时达到峰值,24 h时恢复到照前水平;miR-21的表达量随着照射剂量的增加而发生变化,2Gy时达到峰值,照射剂量进一步加大,miR-21表达量开始下调,与对照组比较具有显著性差异(P<0.05),6Gy时miR-21表达量明显低于未照射组。结论:miR-21对于增加乳腺癌细胞株MDA-MB-231的辐射抗性具有一定作用。
Objective: To study the relationship between the radiosensitivity of MicroRNA-21 and breast cancer cell MDA-MB-231 and its expression. Methods: ①MDA-21 mimics, miR-21 mimics Scramble (negative control), miR-21 inhibitor and miR-21 inhibitor Scramble (negative control) were transfected into breast cancer cells MDA-MB- The changes of the radiation sensitivity of surviving fraction (SF) were detected by RT-PCR. (2) Time-course experiments: After 3, 4, 8, 12 and 24 h exposure to 3Gy X-Ray, PCR was used to detect the expression of miR-21. (3) Quantitative effect test: miR-21 was detected by real-time quantitative PCR after cells were irradiated with 0,1,2,4,6 Gy X-ray for 24 h. Results: After transfected with miR-21mimics, the expression of SF in MDA-MB-231 cells was significantly higher than that in normal controls (P <0.05) (P <0.05). The expression of miR-21 was up-regulated in 3GyX-irradiated breast cancer cell line MDA-MB-231 compared with the control group (P < 0.05). The expression of miR-21 reached the peak at 12 h and returned to the pre-irradiation level at 24 h. The expression of miR-21 changed with the increase of irradiation dose, reaching the peak at 2 Gy and the irradiation dose further increased. The expression level of miR-21 began to decrease, which was significantly different from the control group (P <0.05). The expression of miR-21 at 6 Gy was significantly lower than that of the non-irradiated group. Conclusion: miR-21 may play a role in increasing the radiation resistance of breast cancer cell line MDA-MB-231.