Abstract

The objective of this study was to investigate the effect of arsenic trioxide (As₂O₃) on topoisomerase II levels using western blotting method on MDAH 2774 ovarian carcinoma cell culture. Experimental designs were established to determine the cytotoxic effects of As₂O₃ on MDAH 2774 cells and the IC50 (fatal dose for the 50% of cells) value. Cytotoxicity experiments were carried out using various concentrations of As₂O₃. The 2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) and trypan blue dye–exclusion tests were used to evaluate cytotoxicity. Topoisomerase II expressions were investigated using western blotting method with various concentrations of As₂O₃. Densitometric analysis of topoisomerase 2 bands was carried out using Quantity One 1-D analysis software (Bio-Rad USA, Life Science Research, Hercules, CA). IC50 value of As₂O₃ was found to be 5 × 10⁻⁶ M for MDAH 2774 cells. When the bands were evaluated, it was observed that there was a decrease in topoisomerase II levels in MDAH 2774 cells with increasing concentrations of As₂O₃. It was also observed by the densitometric analysis that topoisomerase II expression ratios of MDAH 2774 cells were decreased by approximately 50% at this concentration. Topoisomerase II levels were significantly decreased with the increasing concentrations of As₂O₃. Inhibition of topoisomerase II enzyme was one of the antiproliferative influence mechanisms of As₂O₃.