effect of sodium arsenite on the expression of antioxidant genes (sod2 and cat) in mcf-7 and jurkat cell lines

background: sodium arsenite (naaso2) has potent cytotoxic activity in human cancer cells. oxidative stress has been suggested as a mechanism for arsenic-induced carcinogenesis. the purpose of the present study was to evaluate the alteration of mrna levels of catalase ( cat ) and superoxide dismutase 2 ( sod2 ) in mcf-7 and jurkat cells after exposure to naaso 2 . methods: methylthiazol tetrazolium (mtt) viability assay was performed to evaluate cytotoxicity of naaso 2 in mcf-7 and jurkat cells. for evaluating the expression levels of the cat and sod2 , we used two concentrations of naaso 2 (5 and 15 µm), lower than the concentrations at which 50% of cell viability were lost. the cells were treated with co-treatment of naaso 2 (15 µm) and n-acetyl-cysteine (nac; 5 µm) in the media for 24 h. the control cells were maintained in sodium arsenite free growth medium. the experiments were done triplicate. using quantitative real-time pcr, the expression levels of cat and sod2 were quantified. one sample student’s t test was performed for comparisons of mrna levels between treatment groups and their corresponding untreated control cells. results: cat mrna level decreased significantly in both cell lines following exposure to naaso 2 ( p <0.05). expression levels of sod2 decreased in jurkat cells and increased in mcf-7 cells after treatment with naaso 2 ( p <0.05). conclusion: after cells exposure to naaso 2 , cat mrna level decreased in both examined cell lines but the alterations of sod2 mrna level is cell specific. the nac modulated the naaso 2 associated alterations of cat and sod2 mrna levels, therefore, the naaso 2 might act through inducing reactive oxygen species.