Related Experiment Videos
Inhibition of Suicidal Erythrocyte Death by Volasertib
Abdulla Al Mamun Bhuyan1, A K M Ashiqul Haque2, Itishri Sahu1
1Department of Internal Medicine III, Eberhard-Karls-University of Tuebingen, Tuebingen, Germany.
Background/Aims:
The Polo-like kinase 1 (Plk1) inhibitor volasertib is used in the treatment of malignancy. Volasertib is partially effective by triggering suicidal death or apoptosis of tumor cells. Similar to apoptosis of nucleated cells, erythrocytes may enter suicidal cell death or eryptosis, which is characterized by cell membrane scrambling with phosphatidylserine translocation to the cell surface and by cell shrinkage. Stimulators of eryptosis include energy depletion, hyperosmotic shock, oxidative stress and excessive increase of cytosolic Ca2+ activity ([Ca2+]i). The present study explored, whether volasertib impacts on eryptosis.
Methods:
Human erythrocytes have been exposed to energy depletion (glucose withdrawal for 48 hours), hyperosmotic shock (addition of 550 mM sucrose for 6 hours), oxidative stress (addition of 0.3 mM tert-butylhydroperoxide [tBOOH] for 50 min) or Ca2+ ionophore ionomycin (1 µM for 60 min) in absence and presence of volasertib (0.5-1.5 µg/ml) and flow cytometry was employed to quantify phosphatidylserine exposure at the cell surface from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3 fluorescence, reactive oxygen species from 2',7'-dichlorodihydrofluorescein diacetate (DCFDA) fluorescence and ceramide abundance utilizing antibodies. For comparison, annexin-V-binding and forward scatter were determined following a 48 hours exposure of human leukemic K562 cells in RPMI-1640 medium to volasertib.
Results:
Treatment with volasertib alone did not significantly modify annexin-V-binding or forward scatter in mature erythrocytes. Energy depletion, hyperosmotic shock, oxidative stress and ionomycin, all markedly and significantly increased the percentage of annexin-V-binding erythrocytes, and decreased the forward scatter. Volasertib significantly blunted the effect of energy depletion and hyperosmotic shock, but not of oxidative stress and ionomycin on annexin-V-binding. Volasertib did not significantly influence the effect of any maneuver on forward scatter. In K562 cells, volasertib enhanced annexin-V-binding and decreased the forward scatter.
Conclusions:
Volasertib is a novel inhibitor of erythrocyte cell membrane scrambling following energy depletion and hyperosmotic shock, effects contrasting the stimulation of K562 cell apoptosis.
Insights
Volasertib, a cancer drug, inhibits suicidal death (eryptosis) in red blood cells induced by energy depletion and osmotic shock. However, it does not affect eryptosis triggered by oxidative stress or calcium influx.
Area of Science:
- Hematology
- Cell Biology
- Pharmacology
Background:
- Polo-like kinase 1 (Plk1) inhibitor volasertib treats malignancy by inducing tumor cell apoptosis.
- Eryptosis, or suicidal red blood cell death, shares features with apoptosis, including phosphatidylserine exposure and cell shrinkage.
- Eryptosis can be triggered by energy depletion, hyperosmotic shock, oxidative stress, and increased intracellular calcium.
Purpose of the Study:
- To investigate the impact of volasertib on eryptosis in human erythrocytes.
- To compare volasertib's effects on red blood cell eryptosis with its effects on cancer cell apoptosis.
Main Methods:
- Human erythrocytes were subjected to eryptosis-inducing conditions (energy depletion, hyperosmotic shock, oxidative stress, ionomycin) with or without volasertib.
- Flow cytometry was used to quantify phosphatidylserine exposure, cell volume, intracellular calcium, reactive oxygen species, and ceramide.
- Human leukemic K562 cells were also treated with volasertib for comparison.
Main Results:
- Volasertib alone did not affect erythrocyte phosphatidylserine exposure or cell volume.
- Volasertib significantly reduced phosphatidylserine exposure caused by energy depletion and hyperosmotic shock.
- Volasertib did not alter volasertib-induced phosphatidylserine exposure from oxidative stress or ionomycin, nor did it affect cell volume changes.
Conclusions:
- Volasertib acts as a novel inhibitor of red blood cell membrane scrambling during eryptosis induced by energy depletion and hyperosmotic shock.
- These findings contrast with volasertib's known effect of stimulating apoptosis in K562 cancer cells.