scholarly journals Triggering of Suicidal Erythrocyte Death by Fascaplysin

2016 ◽  
Vol 39 (4) ◽  
pp. 1638-1647 ◽  
Author(s):  
Morena Mischitelli ◽  
Mohamed Jemaà ◽  
Mustafa Almasry ◽  
Caterina Faggio ◽  
Florian Lang
Keyword(s):  
Oxidative Stress ◽  
Cell Membrane ◽  
Indole Alkaloid ◽  
Annexin V ◽  
Hemoglobin Concentration ◽  
Cell Shrinkage ◽  
Cellular Mechanisms ◽  
Forward Scatter ◽  
Erythrocyte Surface ◽  
Phosphatidylserine Translocation

Background/Aims: The bis-indole alkaloid Fascaplysin is effective against malignancy, an effect at least partially due to stimulation of tumor cell apoptosis. Similar to apoptosis of nucleated cells, erythrocytes could enter suicidal erythrocyte death or eryptosis, characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress and ceramide. The present study explored, whether Fascaplysin induces eryptosis and, if so, to shed light on the cellular mechanisms involved. Methods: Flow cytometry was employed to estimate phosphatidylserine exposure at the cell surface from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, ROS formation from DCFDA dependent fluorescence, and ceramide abundance utilizing specific antibodies. Hemolysis was quantified from the hemoglobin concentration in the supernatant. Results: A 48 hours exposure of human erythrocytes to Fascaplysin (≥ 5 µM) significantly increased the percentage of annexin-V-binding cells, significantly decreased forward scatter, and significantly increased Fluo3-fluorescence, DCFDA fluorescence as well as ceramide abundance. The effect of Fascaplysin on annexin-V-binding and forward scatter was significantly blunted but not abolished by removal of extracellular Ca2+. Conclusions: Fascaplysin triggers cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect at least in part due to Ca2+ entry, oxidative stress and ceramide.

scholarly journals Stimulation of Phospholipid Scrambling of the Erythrocyte Membrane by 9-Cis-Retinoic Acid

2017 ◽  
Vol 41 (2) ◽  
pp. 543-554 ◽  
Author(s):  
Majed Abed ◽  
Kousi Alzoubi ◽  
Florian Lang ◽  
Abdulla  Al Mamun Bhuayn
Keyword(s):  
Retinoic Acid ◽  
Cell Membrane ◽  
Annexin V ◽  
Hemoglobin Concentration ◽  
Cell Shrinkage ◽  
Cellular Mechanisms ◽  
Forward Scatter ◽  
Erythrocyte Surface ◽  
Phosphatidylserine Translocation ◽  
Phospholipid Scrambling

Background/Aims: The endogenous retinoid 9-cis-retinoic acid has previously been shown to trigger apoptosis in a wide variety of cells including several tumor cells and has thus been suggested for the treatment of malignancy. Similar to apoptosis of nucleated cells, erythrocytes may enter suicidal erythrocyte death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Cellular mechanisms participating in the accomplishment of eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i) and formation of ceramide. The present study explored, whether 9-cis-retinoic acid induces eryptosis and whether the effect involves Ca2+ and/or ceramide. Methods: Flow cytometry was employed to estimate erythrocyte volume from forward scatter, phosphatidylserine exposure at the cell surface from annexin-V-binding, [Ca2+]i from Fluo3-fluorescence, and ceramide abundance utilizing specific antibodies. Hemolysis was quantified from hemoglobin concentration in the supernatant. Results: A 48 hours exposure of human erythrocytes to 9-cis-retinoic acid (≥ 0.5 µg/ml) significantly increased the percentage of annexin-V-binding cells and significantly decreased forward scatter. Exposure to 9-cis-retinoic acid (≥ 0.5 µg/ml) significantly increased Fluo3-fluorescence, and the effect of 9-cis-retinoic acid on annexin-V-binding was significantly blunted by removal of extracellular Ca2+. Exposure to 9-cis-retinoic acid (1 µg/ml) further significantly increased the ceramide abundance at the erythrocyte surface and significantly increased hemolysis. Conclusions: 9-cis-retinoic acid triggers phospholipid scrambling of the erythrocyte cell membrane, an effect at least in part downstream of Ca2+ and ceramide.

scholarly journals Stimulation of Eryptosis, the Suicidal Erythrocyte Death by Piceatannol

2016 ◽  
Vol 38 (6) ◽  
pp. 2300-2310 ◽  
Author(s):  
Elena Signoretto ◽  
Michela Castagna ◽  
Florian Lang
Keyword(s):  
Oxidative Stress ◽  
Cell Membrane ◽  
Annexin V ◽  
Hemoglobin Concentration ◽  
Cell Shrinkage ◽  
Cellular Mechanisms ◽  
Cytochrome C Release ◽  
Forward Scatter ◽  
Suicidal Death ◽  
Phosphatidylserine Translocation

Background/Aims: Piceatannol, an analog and metabolite of resveratrol, is effective against various disorders including malignancy. It is in part effective by triggering suicidal death or apoptosis of tumor cells. Cellular mechanisms mediating the proapoptotic effect of Piceatannol include mitochondrial depolarization and cytochrome c release. Erythrocytes lack mitochondria but may nevertheless enter suicidal death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Cellular mechanisms involved in the triggering of eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress and ceramide formation. The present study explored, whether Piceatannol induces eryptosis and, if so, to shed some light on the cellular mechanisms involved. Methods: Phosphatidylserine exposure at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, reactive oxygen species (ROS) formation from 2',7'-dichlorodihydrofluorescein (DCF) diacetate-dependent fluorescence, and ceramide abundance utilizing specific antibodies. Hemoglobin concentration in the supernatant was taken as measure of hemolysis. Results: A 48 hours exposure of human erythrocytes to Piceatannol (10 - 20 µM) significantly increased the percentage of annexin-V-binding cells, significantly decreased forward scatter, significantly increased DCFDA-fluorescence, significantly increased ceramide abundance, but did not significantly increase Fluo3-fluorescence. Removal of extracellular Ca2+ slightly blunted but did not abolish the effect of Piceatannol on annexin-V-binding and forward scatter. Piceatannol (20 µM) significantly augmented the increase of annexin-V-binding, but significantly blunted the decrease of forward scatter following treatment with the Ca2+ ionophore ionomycin. Conclusions: Piceatannol triggers cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect at least in part downstream of Ca2+ and involving oxidative stress and ceramide formation.

scholarly journals Ca2+ Entry, Oxidative Stress, Ceramide and Suicidal Erythrocyte Death Following Diosgenin Treatment

2016 ◽  
Vol 39 (4) ◽  
pp. 1626-1637 ◽  
Author(s):  
Morena Mischitelli ◽  
Mohamed Jemaà ◽  
Mustafa Almasry ◽  
Caterina Faggio ◽  
Florian Lang
Keyword(s):  
Oxidative Stress ◽  
Cell Membrane ◽  
Haemoglobin Concentration ◽  
Annexin V ◽  
Cellular Mechanisms ◽  
Forward Scatter ◽  
Erythrocyte Surface ◽  
Suicidal Death ◽  
Phosphatidylserine Translocation ◽  
Surface Signaling

Background/Aims: The bioactive steroid sapogenin diosgenin is considered for a wide variety of applications including treatment of malignancy. The substance counteracts tumor growth in part by stimulating apoptosis of tumor cells. Similar to apoptosis of nucleated cells, erythrocytes may enter suicidal death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Signaling involved in the stimulation of eryptosis includes increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress and ceramide. The present study explored, whether diosgenin induces eryptosis and, if so, to decipher cellular mechanisms involved. Methods: Flow cytometry was employed to estimate phosphatidylserine exposure at the cell surface from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, ROS formation from DCF dependent fluorescence, and ceramide abundance utilizing specific antibodies. Hemolysis was quantified by determination of haemoglobin concentration in the supernatant. Results: A 48 hours exposure of human erythrocytes to diosgenin significantly increased the percentage of annexin-V-binding cells (≥ 5 µM), significantly decreased forward scatter (15 µM), significantly increased Fluo3-fluorescence (≥ 10 µM), significantly increased DCF fluorescence (15 µM), significantly increased ceramide abundance (15 µM) and significantly increased hemolysis (15 µM). The effect of diosgenin (15 µM) on annexin-V-binding was significantly blunted but not abolished by removal of extracellular Ca2+. Conclusions: Diosgenin stimulates eryptosis with erythrocyte shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect paralleled by and at least in part due to Ca2+ entry, oxidative stress and ceramide.

scholarly journals Triggering of Erythrocyte Cell Membrane Scrambling by Emodin

2016 ◽  
Vol 40 (1-2) ◽  
pp. 91-103 ◽  
Author(s):  
Morena Mischitelli ◽  
Mohamed Jemaà ◽  
Mustafa Almasry ◽  
Caterina Faggio ◽  
Florian Lang
Keyword(s):  
Oxidative Stress ◽  
Cell Membrane ◽  
Annexin V ◽  
Microbial Infection ◽  
Cellular Mechanisms ◽  
Forward Scatter ◽  
Erythrocyte Surface ◽  
Suicidal Death ◽  
Phosphatidylserine Translocation ◽  
Surface Signaling

Background/Aims: The natural anthraquinone derivative emodin (1,3,8-trihydroxy-6-methylanthraquinone) is a component of several Chinese medicinal herbal preparations utilized for more than 2000 years. The substance has been used against diverse disorders including malignancy, inflammation and microbial infection. The substance is effective in part by triggering suicidal death or apoptosis. Similar to apoptosis of nucleated cells erythrocytes may enter suicidal erythrocyte death or eryptosis, characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Signaling involved in the triggering of eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress and ceramide. The present study aimed to test, whether emodin induces eryptosis and, if so, to elucidate underlying cellular mechanisms. Methods: Phosphatidylserine abundance at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, ROS formation from DCFDA dependent fluorescence, and ceramide abundance utilizing specific antibodies. Results: Exposure of human erythrocytes for 48 hours to emodin (≥ 10 µM) significantly increased the percentage of annexin-V-binding cells, and at higher concentrations (≥ 50 µM) significantly increased forward scatter. Emodin significantly increased Fluo3-fluorescence (≥ 10 µM), DCFDA fluorescence (75 µM) and ceramide abundance (75 µM). The effect of emodin on annexin-V-binding was significantly blunted but not abolished by removal of extracellular Ca2+. Conclusions: Emodin triggers phospholipid scrambling of the erythrocyte cell membrane, an effect at least in part due to stimulation of Ca2+ entry and paralleled by oxidative stress and ceramide appearance at the erythroctye surface.

scholarly journals Stimulation of Eryptosis, the Suicidal Erythrocyte Death, by Costunolide

2018 ◽  
Vol 50 (6) ◽  
pp. 2283-2295 ◽  
Author(s):  
Madeline Fink ◽  
Abdulla Al Mamun Bhuyan ◽  
Nefeli Zacharopoulou ◽  
Florian Lang
Keyword(s):  
Oxidative Stress ◽  
Cell Membrane ◽  
Annexin V ◽  
Cell Shrinkage ◽  
Forward Scatter ◽  
Erythrocyte Surface ◽  
Suicidal Death ◽  
Phosphatidylserine Translocation ◽  
Ros Formation ◽  
Binding Cell

Background/Aims: The sesquiterpene lactone Costunolide is effective against various disorders including inflammation and malignancy. The substance is effective in part by triggering suicidal death or apoptosis of tumor cells. Mechanisms involved include altered function of transcription factors and mitochondria. Erythrocytes lack nuclei and mitochondria but are – in analogy to apoptosis of nucleated cells – able to enter suicidal erythrocyte death or eryptosis, characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress and ceramide. The present study explored, whether Costunolide induces eryptosis and, if so, to shed light on the mechanisms involved. Methods: Phosphatidylserine exposure at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, reactive oxygen species (ROS) formation from 2’,7’-dichlorodihydrofluorescein (DCF)-dependent fluorescence, and ceramide abundance utilizing specific antibodies. Results: A 48 hours exposure of human erythrocytes to Costunolide (15 µg/ml) significantly enhanced the percentage of annexin-V-binding cells, significantly decreased forward scatter and significantly increased Fluo3-fluorescence, DCF-fluorescence, and ceramide abundance. The effect of Costunolide on annexin-V-binding was significantly blunted by removal of extracellular Ca2+. Conclusion: Costunolide triggers cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect at least in part due to Ca2+ entry and paralleled by oxidative stress and ceramide formation.

scholarly journals Enhanced Eryptosis Following Exposure to Carnosic Acid

2015 ◽  
Vol 37 (5) ◽  
pp. 1779-1791 ◽  
Author(s):  
Katja Stockinger ◽  
Rosi Bissinger ◽  
Ghada Bouguerra ◽  
Salem Abbès ◽  
Florian Lang
Keyword(s):  
Cell Membrane ◽  
Annexin V ◽  
Human Erythrocytes ◽  
Carnosic Acid ◽  
Cell Shrinkage ◽  
Cellular Mechanisms ◽  
Forward Scatter ◽  
Erythrocyte Surface ◽  
Suicidal Death ◽  
Phosphatidylserine Translocation

Background/Aims: The phenolic abietane diterpene component of rosemary and sage, carnosic acid, may either induce or inhibit apoptosis of nucleated cells. The mechanisms involved in the effects of carnosic acid include altered mitochondrial function and gene expression. Human erythrocytes lack mitochondria and nuclei but are nevertheless able to enter suicidal death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Cellular mechanisms involved in the stimulation of eryptosis include oxidative stress, increase of cytosolic Ca2+ activity ([Ca2+]i), and ceramide formation. The present study explored, whether and how carnosic acid induces eryptosis. Methods: Phosphatidylserine exposure at the cell surface was estimated from annexin V binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, ROS formation from DCFDA dependent fluorescence and ceramide abundance utilizing specific antibodies. Results: A 48 hours exposure of human erythrocytes to carnosic acid significantly increased the percentage of annexin-V-binding cells (2.5 µg/ml), significantly decreased forward scatter (10 µg/ml), significantly increased Fluo3 fluorescence (10 µg/ml), significantly increased ceramide abundance (10 µg/ml), significantly increased hemolysis (10 µg/ml), but significantly decreased DCFDA fluorescence (10 µg/ml). The effect of carnosic acid on annexin-V-binding was significantly blunted, but not abolished by removal of extracellular Ca2+. Conclusion: Carnosic acid triggers cell shrinkage and phospholipid scrambling of the human erythrocyte cell membrane, an effect paralleled by and/or in part due to Ca2+ entry and increased ceramide abundance.

scholarly journals Stimulation of Suicidal Erythrocyte Death by Tafenoquine

2016 ◽  
Vol 39 (6) ◽  
pp. 2464-2476 ◽  
Author(s):  
Abdulla Al Mamun Bhuyan ◽  
Rosi Bissinger ◽  
Katja Stockinger ◽  
Florian Lang
Keyword(s):  
Oxidative Stress ◽  
Cell Membrane ◽  
Annexin V ◽  
Casein Kinase ◽  
Cell Shrinkage ◽  
Cellular Mechanisms ◽  
Forward Scatter ◽  
Suicidal Death ◽  
Phosphatidylserine Translocation ◽  
Stimulation Of

Background/Aims: The 8-aminoquinoline tafenoquine has been shown to be effective against Plasmodia, Leishmania and Trypanosoma. The substance is at least in part effective by triggering apoptosis of the parasites. Similar to apoptosis, erythrocytes may enter suicidal death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Signaling involved in the regulation of eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress, ceramide, zVAD sensitive caspases, SB203580 sensitive p38 kinase, staurosporine sensitive protein kinase C as well as D4476 sensitive casein kinase. The present study explored, whether tafenoquine induces eryptosis and aimed to possibly identify cellular mechanisms involved. Methods: Flow cytometry was employed to estimate phosphatidylserine exposure at the cell surface from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, ROS formation from 2′,7′-dichlorodihydrofluorescein diacetate (DCFDA) dependent fluorescence, and ceramide abundance utilizing specific antibodies. Results: A 48 hours exposure of human erythrocytes to tafenoquine (500 ng/ml) significantly increased the percentage of annexin-V-binding cells, significantly decreased forward scatter, significantly increased Fluo3-fluorescence, and significantly increased DCFDA fluorescence. Tafenoquine did not significantly modify ceramide abundance. The effect of tafenoquine on annexin-V-binding was significantly blunted but not abolished by removal of extracellular Ca2+. The effect of tafenoquine on annexin-V-binding was not significantly blunted by zVAD (10 µM), SB203580 (2 µM) or staurosporine (1 µM). The effect of tafenoquine on annexin-V-binding was significantly blunted but not abolished by D4476 (10 µM). Conclusions: Tafenoquine triggers cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect at least in part due to stimulation of Ca2+ entry, oxidative stress and possibly activation of casein kinase.

scholarly journals Taurolidine Sensitivity of Eryptosis, the Suicidal Erythrocyte Death

2018 ◽  
Vol 51 (2) ◽  
pp. 501-512 ◽  
Author(s):  
Madeline Fink ◽  
Abdulla  Al Mamun Bhuyan ◽  
Nefeli Zacharopoulou ◽  
Florian Lang
Keyword(s):  
Cell Membrane ◽  
Annexin V ◽  
Cell Shrinkage ◽  
Cellular Mechanisms ◽  
Forward Scatter ◽  
Erythrocyte Surface ◽  
Suicidal Death ◽  
Phosphatidylserine Translocation ◽  
Surface Signaling ◽  
Induced Apoptosis

Background/Aims: The taurine derivative Taurolidine is effective against diverse bacteria and tumor growth. In the treatment of cancer, the substance is effective in part by triggering suicidal death or apoptosis of tumor cells. The Taurolidine-induced apoptosis involves mitochondria. Erythrocytes lack mitochondria but are nevertheless able to enter suicidal erythrocyte death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Signaling of eryptosis includes increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress and ceramide. The present study explores, whether Taurolidine induces eryptosis and, if so, which cellular mechanisms are involved. Methods: Phosphatidylserine exposure at the cell surface was estimated using annexin-V-binding, cell volume using forward scatter, [Ca2+]i using Fluo3-fuorescence, reactive oxygen species (ROS) formation using 2’,7’-dichlorodihydrofuorescein (DCF)-dependent fluorescence, and ceramide abundance using specific antibodies. Results: A 48 hours exposure of human erythrocytes to Taurolidine (60 µg/ml) significantly enhanced the percentage of annexin-V-binding cells, significantly decreased forward scatter and significantly increased Fluo3-fluorescence and ceramide abundance, but not DCF-fluorescence. The effect of Taurolidine on annexin-V-binding was virtually abrogated by removal of extracellular Ca2+. Conclusion: Taurolidine triggers cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect at least in part due to Ca2+ entry and paralleled by increase of ceramide abundance.

scholarly journals Camalexin-Induced Cell Membrane Scrambling and Cell Shrinkage in Human Erythrocytes

2017 ◽  
Vol 41 (2) ◽  
pp. 731-741 ◽  
Author(s):  
Mustafa Almasry ◽  
Mohamed Jemaà ◽  
Morena Mischitelli ◽  
Florian Lang ◽  
Caterina Faggio
Keyword(s):  
Cell Membrane ◽  
Kinase Inhibitors ◽  
Annexin V ◽  
Human Erythrocytes ◽  
Cell Shrinkage ◽  
Cellular Mechanisms ◽  
Forward Scatter ◽  
Erythrocyte Surface ◽  
Suicidal Death ◽  
Phosphatidylserine Translocation

Background/Aims: The thaliana phytoalexin Camalexin has been proposed for the treatment of malignancy. Camalexin counteracts tumor growth in part by stimulation of suicidal death or apoptosis of tumor cells. Similar to apoptosis of nucleated cells, erythrocytes may enter suicidal death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Cellular mechanisms contributing to the complex machinery executing eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress, ceramide, protein kinase C and caspases. The present study explored, whether Camalexin induces eryptosis and, if so, to shed light on mechanisms involved. Methods: Phosphatidylserine exposure at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo-3 fluorescence, ROS formation from DCFDA dependent fluorescence, and ceramide abundance utilizing specific antibodies. Results: A 48 hours exposure of human erythrocytes to Camalexin significantly increased the percentage of annexin-V-binding cells (≥ 10 µg/ml), significantly decreased forward scatter (≥ 5 µg/ml) and significantly increased Fluo-3-fluorescence (≥ 10 µg/ml), but did not significantly modify DCFDA fluorescence or ceramide abundance. The effect of Camalexin on annexin-V-binding was significantly blunted by removal of extracellular Ca2+, by kinase inhibitors staurosporine (1 µM) and chelerythrine (10 µM), as well as by caspase inhibitors zVAD (10 µM) and zIETD-fmk (50 µM). Conclusions: Camalexin triggers cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect at least in part depending on Ca2+ entry, as well as staurosporine and chelerythrine sensitive kinase(s) as well as zVAD and zIETD-fmk sensitive caspase(s).

scholarly journals Triggering of Eryptosis, the Suicidal Erythrocyte Death, by Perifosine

2017 ◽  
Vol 41 (6) ◽  
pp. 2534-2544 ◽  
Author(s):  
Jasmin Egler ◽  
Florian Lang
Keyword(s):  
Oxidative Stress ◽  
Annexin V ◽  
Hemoglobin Concentration ◽  
Tumor Cell Death ◽  
Cellular Mechanisms ◽  
Forward Scatter ◽  
Kinase Activation ◽  
Erythrocyte Surface ◽  
Phosphatidylserine Translocation ◽  
Binding Cell

Background/Aims: The alkylphospholipid perifosine is used for the treatment of malignancy. The substance is effective by triggering suicidal tumor cell death or apoptosis. Side effects of perifosine include anemia. At least in theory, perifosine-induced anemia could result from stimulation of suicidal erythrocyte death or eryptosis. Hallmarks of eryptosis are cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Cellular mechanisms participating in the orchestration of eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress, increase of ceramide abundance, as well as activation of staurosporine sensitive protein kinase C and/or of SB203580 sensitive p38 kinase. The present study explored, whether perifosine induces eryptosis and, if so, whether its effect involves and/or requires Ca2+ entry, oxidative stress, ceramide and kinase activation. Methods: 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 (ROS) abundance from DCFDA dependent fluorescence, and ceramide abundance utilizing specific antibodies. Hemolysis was estimated from hemoglobin concentration in the supernatant. Results: A 24 hours exposure of human erythrocytes to perifosine (2.5 µg/ml) significantly increased the percentage of annexin-V-binding cells, significantly decreased average forward scatter, significantly increased the percentage of shrunken erythrocytes, and significantly decreased the percentage of swollen erythrocytes. Perifosine significantly increased the percentage of hemolytic erythrocytes. Perifosine significantly increased Fluo3-fluorescence, but decreased DCFDA fluorescence and ceramide abundance. The effect of perifosine on annexin-V-binding was significantly blunted by removal of extracellular Ca2+ and by addition of staurosporine (1 µM), but not by addition of SB203580 (2 µM). Conclusions: Perifosine triggers eryptosis, an effect at least in part due to Ca2+ entry and activation of staurosporine sensitive kinases.

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