Fig. 6: High glucose and ROS primes cells to undergo necroptosis, while preventing apoptosis in the absence of death receptor ligands.

U937 cells were grown in 10 or 50 mM glucose in the presence or absence of superoxide dismutase inhibitor, diethyldithiocarbamate (DDC), for 24 h. Cells were then stained with A Cellrox Green or B MitoSOX Red, and analyzed by flow cytometry. There is a robust increase in staining for both reagents in cells grown in 50 mM glucose or those treated with DDC in normal glucose. Results in A and B are from three independent experiments. Graphed values represent mean ± standard deviation. Two-way ANOVA, ***p < 0.001. C U937 cells were grown in the presence or absence of DDC for 24 h followed by immunoblotting. RIP1 exists as a high MW, oxidized species in cells grown in 50 mM glucose or those treated with DDC. D U937 cells were treated as in C. Caspases-3, -6, and -7 decrease in cells grown in 50 mM glucose or treated with DDC. These results indicate that high glucose or ROS predispose cells to undergo necroptosis in the absence of TNF-α or other death receptor ligands. All western blot images are representative of three independent experiments.