ABSTRACT
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 NaAsO2. METHODS: Methylthiazol tetrazolium (MTT) viability assay was performed to evaluate cytotoxicity of NaAsO2 in MCF-7 and Jurkat cells. For evaluating the expression levels of the CAT and SOD2, we used two concentrations of NaAsO2 (5 and 15 µM), lower than the concentrations at which 50% of cell viability were lost. The cells were treated with co-treatment of NaAsO2 (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 NaAsO2 (P<0.05). Expression levels of SOD2 decreased in Jurkat cells and increased in MCF-7 cells after treatment with NaAsO2 (P<0.05). CONCLUSION: After cells exposure to NaAsO2, CAT mRNA level decreased in both examined cell lines but the alterations of SOD2 mRNA level is cell specific. The NAC modulated the NaAsO2 associated alterations of CAT and SOD2 mRNA levels, therefore, the NaAsO2 might act through inducing reactive oxygen species.
