Keywords: micronucleus, breast cancer, irradiation, comet assay, DNA damage, T-47D, MCF-7, cancer cells, ionising radiation, low radiation, cancer treatment, deficient DNA repair, radioinduced damage, radioresistance, genotoxicity
Evaluation of radioinduced damage and repair capacity in human breast cancer cells, MCF-7 and T-47D
Ionising radiation is an established etiological agent for breast cancer, but is also a therapeutic modality used in cancer treatment. The accumulation of deoxyribonucleic acid (DNA) damage and deficient DNA repair are considered susceptibility factors that predispose individuals to breast cancer development. In the present study, the genetic damage induced by gamma radiation and repair capacity in the target cells, i.e., cell lines originating from breast cancer, were analysed using a micronucleus (MN) test and comet assay (single-cell alkaline gel electrophoresis). Two breast tumour cell lines, MCF-7 and T-47D, were irradiated in a 60Co source (0.722 Gy/min) with various doses (0.5, 1.0, 2.0, 4.0 and 5.0 Gy). Cytogenetic data showed similar spontaneous damage of two cell lines; the radioinduced damage, however, was higher in T-47D starting from 2 Gy, with a more accelerated proliferation rate than MCF-7 at all analysed doses. Both tumour cell lines were able to repair a considerable part of the radioinduced damage within 1 h after exposure, indicating a relative radioresistance of these cell lines to the genotoxic action of ionising radiation.