Figure 5

APR-246 and MQ reduce glutathione levels in ovarian cancer cells. (a–d) Effects of APR-246 and MQ on intracellular glutathione levels in A2780 and in A2780-CP20 ovarian cancer cells. Total GSH levels (GSH+2 × GSSG) were measured using Cayman Glutathione Assay kit. The results are shown as mean±S.E.M. (n=2). (e and f) MQ forms a Michael adduct with glutathione. (e) Liquid chromatography trace of the reaction mixture after addition of excess glutathione (GSH) shows total consumption of MQ. Product and GSH co-eluates under the conditions used. (f) Mass spectrometry (MS) of the retention time 0.42 peak shows the typical MS pattern of the GS-MQ adduct (m/z: 445 +223). MS-peak of GSH (in excess): m/z: 308 [m+H]. The typical MS pattern of the GS-MQ adduct (m/z: 445 and 223) and the slight excess of added GSH to the reaction mixture is shown by the MS peak m/z=308 [m+H]. The results shown in (e–f) are representative of three independent experiments