Sulforaphane, an isothiocyanate from cruciferous vegetable, counteracts malignancy. The effect is at least in part due to the stimulation of suicidal death or apoptosis of tumour cells. Mechanisms invoked in sulforaphane-induced apoptosis include mitochondrial depolarization and altered gene expression. Despite the lack of mitochondria and nuclei, erythrocytes may, similar to apoptosis of nucleated cells, enter eryptosis, a suicidal cell death characterized by cell shrinkage and phosphatidylserine translocation to the erythrocyte surface. Stimulators of eryptosis include increase of cytosolic Ca(2+)-activity ([Ca(2+)]i). This study explored whether sulforaphane stimulates eryptosis. Cell volume was estimated from forward scatter, phosphatidylserine exposure at the cell surface from annexin V binding and [Ca(2+)]i from Fluo-3 fluorescence. A 48-hr treatment of human erythrocytes with sulforaphane (50-100 μM) significantly decreased forward scatter, significantly increased the percentage of annexin V binding cells and significantly increased [Ca(2+)]i. The effect of sulforaphane (100 μM) on annexin V binding was significantly blunted but not abrogated by the removal of extracellular Ca(2+). Sulforaphane (100 μM) significantly increased ceramide formation. In conclusion, sulforaphane stimulates suicidal erythrocyte death or eryptosis, an effect at least partially, but not exclusively, due to the stimulation of Ca(2+) entry and ceramide formation.
© 2014 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).