Breast cancer cell response to ionizing radiation / Agnė Bartnykaitė, Rasa Ugenskienė, Arturas Inčiūra, Elona Juozaitytė

Radiobiology

ISBN 978-86-901150-1-3.

Acknowledgments: This project has received funding from the European Union's H2020 Research and Innovation Programme, under Grant Agreement No: 730983.

Background. Nowadays breast cancer is one of the most common cancers around the world and the radiotherapy is one of the highly targeted and effective ways to destroy cancer cells. There is still an urgent need of clinical and basic research in order to improve the effectiveness of radiotherapy in cancer treatment. Lithuanian University of Health Sciences participates in Horizon 2020 project “INfraStructure in Proton International Research” (INSPIRE) in the Framework Programme for Research and Innovation. The aim of INSPIRE project is to integrate infrastructures in proton beam therapy research. Consequently, in this project we aimed to study the molecular basis of breast cancer cell resistance to ionizing radiation. For this purpose, the survival, the extent of apoptosis and cell cycle delay in irradiated MDA-MB-231 breast cancer cells were analyzed. Materials and methods. Commercially available MDA-MB-231 breast cancer cells were exposed to different doses of ionizing radiation (IR) from Clinac 2100C/D linear accelerator. Colony forming assay was performed for cell survival analysis following irradiation. The intensity of the radiation-induced apoptosis and cell-cycle delay were measured via flow cytometer analysis. Results. In colony forming assay the fraction of surviving cells was 51.6%±2.15 following the exposure to 2 Gy. The survival decreased with IR doses, however, the results suggested that MDA-MB-231 cells were rather resistant to IR. Furthermore, the early radiation-induced apoptosis analysis showed no apoptotic response after 24 hours following the exposure to IR. A significant amount of apoptotic cells was found at 48 hour time-point following the exposure to 8 and 10 Gy of IR. In addition, the cell cycle analysis revealed IR induced arrest of MDA-MB-231 cells in the G2/M phase, which indicated that entry into mitosis had been delayed. Conclusions. We concluded that MDA-MB-231 cell line is [...].