Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
Endocrine Research Center, Institute of Endocrinology and Metabolism, Iran University of Medical Sciences (IUMS), Tehran, Iran.
Sci Rep. 2020 Jun 3;10(1):9054. doi: 10.1038/s41598-020-65680-z.
Radiotherapy is a fundamental step in the treatment of breast cancer patients. The treatment efficiency is however reduced by the possible onset of radiation resistance. In order to develop the effective treatment approach, it is important to understand molecular basis of radiosensitivity in breast cancer. The purpose of the present study was to investigate different radiation response of breast cancer cell lines, and find out if this response may be related to change in the microRNAs expression profile. MDA-MB-231 and T47D cells were subjected to different doses of radiation, then MTT and clonogenic assays were performed to assess radiation sensitivity. Cytofluorometric and western blot analysis were performed to gain insight into cell cycle distribution and protein expression. MicroRNA sequencing and bioinformatics prediction methods were used to identify the difference in microRNAs expression between two breast cancer cells and the related genes and pathways. T47D cells were more sensitive to radiation respect to MDA-MB-231 cells as demonstrated by a remarkable G2 cell cycle arrest followed by a greater reduction in cell viability and colony forming ability. Accordingly, T47D cells showed higher increase in the phosphorylation of ATM, TP53 and CDK1 (markers of radiation response) and faster and more pronounced increase in RAD51 and γH2AX expression (markers of DNA damage), when compared to MDA-MB-231 cells. The two cell lines had different microRNAs expression profiles with a confirmed significant differential expression of miR-16-5p, which targets cell cycle related genes and predicts longer overall survival of breast cancer patients, as determined by bioinformatics analysis. These results suggest a possible role for miR-16-5p as radiation sensitizing microRNA and as prognostic/predictive biomarker in breast cancer.
放射治疗是乳腺癌患者治疗的重要步骤。然而，放射治疗的效果会因可能发生的放射抗性而降低。为了开发有效的治疗方法，了解乳腺癌放射敏感性的分子基础非常重要。本研究的目的是研究不同乳腺癌细胞系的放射反应，并确定这种反应是否与 microRNAs 表达谱的变化有关。MDA-MB-231 和 T47D 细胞接受不同剂量的辐射，然后进行 MTT 和集落形成测定以评估放射敏感性。通过细胞荧光和 Western blot 分析了解细胞周期分布和蛋白表达。通过 microRNA 测序和生物信息学预测方法，鉴定两种乳腺癌细胞之间 microRNAs 表达的差异及其相关基因和通路。与 MDA-MB-231 细胞相比，T47D 细胞对辐射更敏感，表现为明显的 G2 细胞周期阻滞，随后细胞活力和集落形成能力显著降低。相应地，T47D 细胞中 ATM、TP53 和 CDK1 的磷酸化（放射反应标志物）增加更为显著，RAD51 和 γH2AX 的表达（DNA 损伤标志物）更快且更为明显增加，与 MDA-MB-231 细胞相比。两种细胞系具有不同的 microRNAs 表达谱，miR-16-5p 的表达水平存在显著差异，通过生物信息学分析证实其可靶向细胞周期相关基因，并预测乳腺癌患者的总生存期更长。这些结果表明，miR-16-5p 可能作为放射增敏 microRNA 以及作为乳腺癌的预后/预测生物标志物发挥作用。
