Inhibition of TrxR. (A) To determine the inhibitory effect of [Au(SCN)(PEt₃)] on TrxR, a control experiment was performed where cell line U1810 was cultured with medium containing the gold(I) compound. Cells grown with 2.5 μM [Au(SCN)(PEt₃)] were harvested at 24 and 48 hrs and TrxR activity was measured and compared to untreated controls. The y-axis denotes ng-active TrxR/mg total protein. Error bars show standard deviation of triplicates. (B) Cell line U1810 was also continuously cultured with 0.05 μM [Au(SCN)(PEt₃)] after the initial 48 hrs treatment. Cells were harvested after 3, 6 and 9 days and TrxR activity measured and compared to untreated control. The y-axis denotes ng-active TrxR/mg total protein. Error bars show standard deviation of triplicates. (C) Cell line U1810 was transfected with siRNA directed at TrxR1 and mRNA levels measured with qPCR after 24, 48 and 72 hrs (black bars). A scrambled siRNA sequence was used as negative control (grey bars). Levels of mRNA were normalized to levels of untreated controls (white bars). Error bars show standard deviation of triplicates. (D) The effect of siRNA transfection on protein level was confirmed with Western blot analysis.