Comparison of the radiosensitivity of cancer and normal cells to X-ray irradiation using MTT assay: An in-vitro study

Background: MTT assay [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] is a sensitive and accurate method to determine survival fraction of irradiated cancer cells. The aim of present study was to evaluate the radiosensitivity of cancer cells X-ray Irradiation in comparison to normal cells using the MTT assay. Methods: Four cancer cell lines were used, the mouse breast 4T1 cells, the mouse fibroblast L929 cells, the human gastric AGS cells, and the human dermal fibroblasts (HDF) cells. For each cell line, MTT assay was carried out after irradiation to 0, 2, 4, and 6 Gy. For MTT assay, the relationship between absorbed dose and cell number, optimal seeding of cell number, and optimal timing of assay were determined. Then, MTT assay was performed when the irradiated cells had regained exponential growth, or when the non-irradiated cells had undergone doubling times. Findings: With increasing radiation dose, the mortality of the cells increased, and radiation blocked cell growth. Conclusion: The response of different cells to irradiation was different. MTT assay may successfully be used, and also may distinguish cell responses to different photon energies. MTT assay was undertaken with optimal assay conditions, and showed the sensitivity of cells to irradiation with regard to the plating efficiency of each cell line, and doubling time at least. © 2018, Isfahan University of Medical Sciences(IUMS). All rights reserved.