Enhanced eryptosis following auranofin exposure

The antiinflammatory, antimicrobial and anticancer drug auranofin has previously been shown to trigger apoptosis, the suicidal death of nucleated cells. Side effects of the drug include anaemia. At least in theory the anaemia could result from stimulation of suicidal death of erythrocytes or eryptosis, which involves cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface.

Stimulators of eryptosis include oxidative stress and increase of cytosolic Ca2+-activity ([Ca2+]i). In the present study, phosphatidylserine exposure at the cell surface was estimated from annexin V binding, cell volume from forward scatter, hemolysis from hemoglobin release, reactive oxygen species (ROS) from 2',7'-dichlorodihydrofluorescein diacetate (DCFDA) fluorescence, and [Ca2+]i from Fluo3-fluorescence.

A 24 hours exposure of human erythrocytes to auranofin (≥5 µg/ml) significantly increased the percentage of annexin-V-binding cells (from 2.2 ± 0.5 to 17.4 ± 1.5%), significantly decreased forward scatter and significantly enhanced ROS. At higher concentrations (10 µg/ml) auranofin triggered slight hemolysis (from 2.1 ± 0.2 to 3.2 ± 0.3%).

Auranofin stimulates cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect at least partially due to induction of oxidative stress.