radiation-induced bystander effect via grid radiotherapy and medium transfer in the a-375 human melanoma cancer cell line: an in-vitro study

Purpose: the goal of this research was to investigate the bystander effect in the a-375 cell line under the spatially fractionated radiation therapy (grid therapy technique). in grid therapy, due to direct and indirect cell damage after high-dose radiation, evaluation of radiation-induced bystander effects (ribe) is of the most importance for investigating the risk of therapy.materials and methods: the potential role of ribe was evaluated with different doses of 6 mev electron radiation and different incubation times after irradiation using two methods; grid therapy and medium transfer. colony formation assay (cfa) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2h-tetrazolium bromide (mtt) test were used to detect the mentioned effects. alpha and beta parameters were calculated from the cell survival curve by the quadratic-linear model.results: the result showed that the survival fraction significantly decreases by increasing the radiation dose for both bystander and irradiated cells. however, a decrease in the number of colony-forming cells caused by electron radiation greater than 4mev to target cells was significantly increased compared with bystander cells (p < 0.05). while increasing the incubation time after exposure to an electron beam, it had no significant effect on cell survival fraction (p > 0.05). furthermore, the ribe level in non-target cells increased up to a dose of 4gy, but decreased significantly at doses higher than 4gy. this result in high doses confirmed that a negative feedback mechanism was responsible for reducing the ribe response.conclusion: based on the results, we can state there are classic radiation-induced bystander effects in a-375 monolayer exposed by grid therapy and medium transfer technique, which can play an important role in pre-clinical and clinical studies.