FONSECA, D.C.OCAMPO, I.Z.VIEIRA, D.P.2019-07-242019-07-242018FONSECA, D.C.; OCAMPO, I.Z.; VIEIRA, D.P. Genotoxic and anti-proliferative effects of aminoguanidine on gamma-irradiated MCF-7 breast cancer cells. <b>Brazilian Journal of Radiation Sciences</b>, v. 7, p. 1-20, 2018. DOI: <a href="https://dx.doi.org/10.15392/bjrs.v7i1.788">10.15392/bjrs.v7i1.788</a>. Disponível em: http://repositorio.ipen.br/handle/123456789/29944.2319-0612http://repositorio.ipen.br/handle/123456789/29944The intracellular production of nitric oxide is studied as a relevant phenomenon in exposure to ioniz-ing radiation. There is evidence of local nitric oxide production in solid tumors. The study evaluated the effects of the administration of aminoguanidine, a selective inhibitor of an isoform of nitric oxide synthase on the frequency of genotoxic damage, loss of clonogenic potential and induction of cytotoxicity after ex-posure of human breast tumor (MCF7) cells to ionizing radiation in radiotherapeutic doses. Cells were treated with aminoguanidine (1 or 2 mM) and irradiated by gamma radiation at doses between 0.5 and 8Gy. In cultures treated with 1 mM, we observed increased cytotoxicity and genotoxicity, and reduction of the clonogenic potential of the colonies. Alternatively, 2 mM aminoguanidine produced the opposite effect, apparently protecting cultures from the effects of exposures. The experiments suggested that the admin-istration of aminoguanidine may reduce the in vitro radiosensitivity of tumors due to the increase of the frequency of genotoxic damage.1-20openAccessneoplasmsmammary glandsradiationsnitric oxideionizing radiationsbiological radiation effectsdna damagesgamma radiationguanidinesin vitrotumor cellstoxicityradiosensitivityArtigo de periódico710.15392/bjrs.v7i1.7880000-0002-0007-534Xhttps://orcid.org/0000-0002-0007-534X