Metabolic exhaustion and casein kinase 1α drive deguelin-induced premature red blood cell death

Apoptosis and eryptosis: similarities and differences

Eryptosis is a regulated cell death (RCD) of mature erythrocytes initially described as a counterpart of apoptosis for enucleated cells. However, over the recent years, a growing number of studies have emphasized certain differences between both cell death modalities. In this review paper, we underline the hallmarks of eryptosis and apoptosis and highlight resemblances and dissimilarities between both RCDs. We summarize and critically discuss differences in the impact of caspase-3, Ca2+ signaling, ROS signaling pathways, opposing roles of casein kinase 1α, protein kinase C, Janus kinase 3, cyclin-dependent kinase 4, and AMP-activated protein kinase to highlight a certain degree of divergence between apoptosis and eryptosis. This review emphasizes the crucial importance of further studies that focus on deepening our knowledge of cell death machinery and identifying novel differences between cell death of nucleated and enucleated cells. This might provide evidence that erythrocytes can be defined as viable entities capable of programmed cell destruction. Additionally, the revealed cell type-specific patterns in cell death can facilitate the development of cell death-modulating therapeutic agents.

Rosmarinic Acid Elicits Calcium-Dependent and Sucrose-Sensitive Eryptosis and Hemolysis through p38 MAPK, CK1α, and PKC

BACKGROUND

Rosmarinic acid (RA) possesses promising anticancer potential, but further development of chemotherapeutic agents is hindered by their toxicity to off-target tissue. In particular, chemotherapy-related anemia is a major obstacle in cancer therapy, which may be aggravated by hemolysis and eryptosis. This work presents a toxicity assessment of RA in human RBCs and explores associated molecular mechanisms.

METHODS

RBCs isolated from healthy donors were treated with anticancer concentrations of RA (10-800 μM) for 24 h at 37 °C, and hemolysis and related markers were photometrically measured. Flow cytometry was used to detect canonical markers of eryptosis, including phosphatidylserine (PS) exposure by annexin-V-FITC, intracellular Ca2+ by Fluo4/AM, cell size by FSC, and oxidative stress by H2DCFDA. Ions and pH were assessed by an ion-selective electrode, while B12 was detected by chemiluminescence.

RESULTS

RA elicited concentration-dependent hemolysis with AST and LDH release but rescued the cells from hypotonic lysis at sub-hemolytic concentrations. RA also significantly increased annexin-V-positive cells, which was ameliorated by extracellular Ca2+ removal and isosmotic sucrose. Furthermore, a significant increase in Fluo4-positive cells and B12 content and a decrease in FSC and extracellular pH with KCl efflux were noted upon RA treatment. Hemolysis was augmented by blocking KCl efflux and was blunted by ATP, SB203580, staurosporin, D4476, isosmotic urea, and PEG 8000.

CONCLUSIONS

RA stimulates Ca2+-dependent and sucrose-sensitive hemolysis and eryptosis characterized by PS exposure, Ca2+ accumulation, loss of ionic regulation, and cell shrinkage. These toxic effects were mediated through energy deprivation, p38 MAPK, protein kinase C, and casein kinase 1α.

Stimulation of Hemolysis and Eryptosis by β-Caryophyllene Oxide

BACKGROUND

Eryptosis stimulated by anticancer drugs can lead to anemia in patients. β-caryophyllene oxide (CPO) is an anticancer sesquiterpene present in various plants; however, its effect on the structure and function of human red blood cells (RBCs) remains unexplored. The aim of this study was to investigate the hemolytic and eryptotic activities and underlying molecular mechanisms of CPO in human RBCs.

METHODS

Cells were treated with 10-100 μM of CPO for 24 h at 37 °C, and hemolysis, LDH, AST, and AChE activities were photometrically assayed. Flow cytometry was employed to determine changes in cell volume from FSC, phosphatidylserine (PS) externalization by annexin-V-FITC, intracellular calcium by Fluo4/AM, and oxidative stress by 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA). Cells were also cotreated with CPO and specific signaling inhibitors and antihemolytic agents. Furthermore, whole blood was exposed to CPO to assess its toxicity to other peripheral blood cells.

RESULTS

CPO induced concentration-responsive hemolysis with LDH and AST leakage, in addition to PS exposure, cell shrinkage, Ca2+ accumulation, oxidative stress, and reduced AChE activity. The toxicity of CPO was ameliorated by D4476, staurosporin, and necrosulfonamide. ATP and PEG 8000 protected the cells from hemolysis, while urea and isotonic sucrose had opposite effects.

CONCLUSIONS

CPO stimulates hemolysis and eryptosis through energy depletion, Ca2+ buildup, oxidative stress, and the signaling mediators casein kinase 1α, protein kinase C, and mixed lineage kinase domain-like pseudokinase. Development of CPO as an anticancer therapeutic must be approached with prudence to mitigate adverse effects on RBCs using eryptosis inhibitors, Ca2+ channel blockers, and antioxidants.

Eriocitrin Disrupts Erythrocyte Membrane Asymmetry through Oxidative Stress and Calcium Signaling and the Activation of Casein Kinase 1α and Rac1 GTPase

BACKGROUND

Hemolysis and eryptosis result in the premature elimination of circulating erythrocytes and thus contribute to chemotherapy-related anemia, which is extremely prevalent in cancer patients. Eriocitrin (ERN), a flavanone glycoside in citrus fruits, has shown great promise as an anticancer agent, but the potential toxicity of ERN to human erythrocytes remains unstudied.

METHODS

Erythrocytes were exposed to anticancer concentrations of ERN (10-100 μM) for 24 h at 37 °C, and hemolysis and associated markers were quantified using colorimetric assays. Eryptosis was assessed by flow cytometric analysis to detect phosphatidylserine (PS) exposure by annexin-V-FITC, intracellular Ca2+ using Fluo4/AM, and oxidative stress with 2-,7-dichlorodihydrofluorescin diacetate (H2DCFDA). ERN was also tested against specific signaling inhibitors and anti-hemolytic agents.

RESULTS

ERN caused significant, concentration-dependent hemolysis at 20-100 μM. ERN also significantly increased the percentage of eryptotic cells characterized by Ca2+ elevation and oxidative stress. Furthermore, the hemolytic activity of ERN was significantly ameliorated in the presence of D4476, NSC23766, isosmotic urea and sucrose, and polyethylene glycol 8000 (PEG). In whole blood, ERN significantly elevated MCV and ESR, with no appreciable effects on other peripheral blood cells.

CONCLUSIONS

ERN promotes premature erythrocyte death through hemolysis and eryptosis characterized by PS externalization, Ca2+ accumulation, membrane blebbing, loss of cellular volume, and oxidative stress. These toxic effects, mediated through casein kinase 1α and Rac1 GTPase, can be ameliorated by urea, sucrose, and PEG. Altogether, these novel findings are relevant to the further development of ERN as an anticancer therapeutic.

Tamoxifen induces eryptosis through calcium accumulation and oxidative stress

Chemotherapy-related anemia is a major obstacle in anticancer therapy. Tamoxifen (TAM) is an antiestrogen prescribed for breast cancer patients with hemolytic potential and apoptotic properties in nucleated cells. However, the eryptotic activity of TAM has hitherto escaped the efforts of investigators. RBCs from apparently healthy volunteers were treated with 1-50 μM of TAM for 24 h at 37 °C. Hemoglobin leakage and LDH, AST, and AChE activities were photometrically determined while K+, Na+, and Mg2+ were detected by ion-selective electrode. Flow cytometry was used to identify eryptotic cells by annexin-V-FITC, intracellular Ca2+ by Fluo4/AM, sell size and morphology by FSC and SSC signals, respectively, and oxidative stress by H2DCFDA. Whole blood was also exposed to 30 μM of TAM for 24 h at 37 °C to examine the toxicity of TAM to WBCs and platelets. TAM caused Ca2+-independent, dose-responsive hemolysis accompanied by K+, LDH, and AST leakage without improving the mechanical stability of RBCs in hypotonic environments. TAM treatment also increased the proportion of cells positive for annexin-V-FITC, Fluo4, and DCF, along with diminished FSC and SSC signals and AChE activity. Notably, TAM toxicity was aggravated by sucrose but abrogated by vitamin C, PEG 8000, and urea. Moreover, TAM exhibited distinct cytotoxic profiles against leukocytes and platelets. TAM-induced eryptosis is characterized by breakdown of membrane asymmetry, inhibition of AChE activity, Ca2+ accumulation, cell shrinkage, and oxidative stress. Vitamin C, PEG 8000, and urea may hold promise to subvert the undesirable toxic effects of TAM on RBCs.

Stimulation of Hemolysis and Eryptosis by α-Mangostin through Rac1 GTPase and Oxidative Injury in Human Red Blood Cells

BACKGROUND

Chemotherapy-related anemia is prevalent in up to 75% of patients, which may arise due to hemolysis and eryptosis. Alpha-mangostin (α-MG) is a polyphenolic xanthonoid found in the mangosteen tree (Garcinia mangostana) whose antitumor medicinal properties are well-established. Nevertheless, the potential toxic effects of α-MG on red blood cells (RBCs) have, as of yet, not been as well studied.

METHODS

RBCs were exposed to 1-40 μM of α-MG for 24 h at 37 °C. Hemolysis and related markers were measured using colorimetric assays, eryptotic cells were identified through Annexin-V-FITC, Ca2+ was detected with Fluo4/AM, and oxidative stress was assessed through H2DCFDA using flow cytometry. The toxicity of α-MG was also examined in the presence of specific signal transduction inhibitors and in whole blood.

RESULTS

α-MG at 10-40 μM caused dose-dependent hemolysis with concurrent significant elevation in K+, Mg2+, and LDH leakage, but at 2.5 μM it significantly increased the osmotic resistance of cells. A significant increase was also noted in Annexin-V-binding cells, along with intracellular Ca2+, oxidative stress, and cell shrinkage. Moreover, acetylcholinesterase activity was significantly inhibited by α-MG, whose hemolytic potential was significantly ameliorated by the presence of BAPTA-AM, vitamin C, NSC23766, and isosmotic sucrose but not urea. In whole blood, α-MG significantly depleted intracellular hemoglobin stores and was selectively toxic to platelets and monocytes.

CONCLUSIONS

α-MG possesses hemolytic and eryptotic activities mediated through Ca2+ signaling, Rac1 GTPase activity, and oxidative injury. Also, α-MG leads to accelerated cellular aging and specifically targets platelet and monocyte populations in a whole blood milieu.