Cell cycle dependent modulating effects of melatonin on radiation induced cytogenetic damages in lymphocytes of normal individuals and breast cancer patients

Background: The use of radioprotectors to ameliorate the deleterious effects of radiation could be an option to reduce normal tissue radiotoxicity.In this study, melatonin as an efficient naturally occurring antioxidant was used to explore its modulating effects on radiation induced cytogenetic damages at G0 and G2lymphocytes of control and breast cancer (BC) patients.Materials and Methods:Whole blood samples were collected from 20 BC patients, and also 10 healthy individuals.Lymphocyte culture was initiated, irradiation was applied in G0lymphocytes 1 hour before culture initiation using a 6 MV linear accelerator at dose of 3Gy and 4 hours before harvesting for G2-lymphocytes at a dose of 1Gy in the presence or absence of melatonin (800 µg/ml).Cytogenetic damages were assessed using cytochalasin-B blocked micronucleus (CBMN) assay and chromosomal aberrations were analyzed using G2-assay according to standard methods.Data were statistically analyzed and P-value