Fig. 3.

JS-K toxicity depends on intracellular ROS/RNS. A, JS-K toxicity (as IC₅₀ values) correlated significantly with endogenous ROS/RNS levels, measured as DCF fluorescence (arbitrary units). B, pretreatment with NAC reduced JS-K toxicity, whereas depletion of glutathione using the glutathione synthase inhibitor BSO sensitized the cells to JS-K. The H1703 cells were treated with NAC or BSO for 24 h, followed by 24 h with 1 μM JS-K. The number of surviving cells was assessed by the MTT assay. a, P < 0.0001; b, P = 0.003; c, P = 0.04 by Mann-Whitney test. C, depletion of GSH in the H1944 cells sensitized the cells to JS-K. Cells were treated with 1 mM BSO in complete medium for 24 h followed by 10 μM JS-K for another 24 h, and the number of surviving cells was assessed by the MTT assay.