SF increases ROS concentration and inhibits GSH detoxification in MDR cancer cell lines.

<p>Flow-cytometric measurements of dihydroethidium (DHE)-fluorescence correspond to cellular ROS levels (<b>A</b>). Mean fluorescence intensity (MFI) calculated after correction for autofluorescence is presented. The data indicate the average ± S.D. of three experiments carried out in triplicate. Statistical significance of SF treatment compared to untreated control: p<0.01 (**) and p<0.001 (***). Detection of GSH concentration (<b>B</b>) for each sample was performed at least six times. The data indicate the average ± S.D. Statistical significance of SF treatment compared to untreated control: p<0.01 (**). The expression of <i>gst-π</i> mRNA in NCI-H460/R (<b>C</b>) and U87-TxR cells (<b>D</b>) was evaluated relative to the internal control - <i>β-actin</i>. The PCR products were separated on agarose gels beside a 100 bp DNA ladder. Statistical significance between treated and untreated cells is presented as p<0.001 (***).The decreases in γGCS expression in NCI-H460/R (<b>E</b>) and U87-TxR cells (<b>F</b>) after SF treatments were calculated relative to β-actin expression and untreated samples. Statistical significance between treated and untreated cells is presented as p<0.01 (**).