Stimulation of eryptosis by cryptotanshinone

Background/Aims: Cryptotanshinone, a component of Salvia miltiorrhiza Bunge roots, may trigger suicidal death or apoptosis of tumor cells and has thus been recommended for the prevention and treatment of malignancy. On the other hand, Cryptotanshinone has been shown to counteract apoptosis of neurons and hepatocytes. Similar to apoptosis of nucleated cells, erythrocytes may enter eryptosis, a suicidal death characterized by cell shrinkage and phosphatidylserine translocation to the erythrocyte surface. Eryptosis may be triggered by increase of cytosolic Ca2+-activity ([Ca2+]i). The present study explored whether Cryptotanshinone stimulates eryptosis. Methods: Forward scatter was taken as measure of cell volume, annexin V binding for identification of phosphatidylserine-exposing erythrocytes and Fluo3-fluorescence for determination of [Ca2+]i. Results: A 48 h exposure of human erythrocytes to Cryptotanshinone (10 µM) was followed by significant decrease of forward scatter, significant increase of the percentage annexin-V-binding cells and significant increase of [Ca2+]i. The effect of Cryptotanshinone (1 µM) on annexin-V-binding was virtually abrogated by removal of extracellular Ca2+. Conclusion: Cryptotanshinone is a powerful stimulator of suicidal erythrocyte death or eryptosis, which is effective mainly, if not exclusively, by stimulation of Ca2+ entry.