Department of Physiology, University of Tuebingen, Gmelinstr. 5, Tuebingen D-72076, Germany.
Toxins (Basel). 2013 Apr 19;5(4):703-16. doi: 10.3390/toxins5040703.
The nitrosourea alkylating agent, carmustine, is used as chemotherapeutic drug in several malignancies. The substance triggers tumor cell apoptosis. Side effects of carmustine include myelotoxicity with anemia. At least in theory, anemia could partly be due to stimulation of eryptosis, the suicidal death of erythrocytes, characterized by cell shrinkage and breakdown of phosphatidylserine asymmetry of the cell membrane with phosphatidylserine exposure at the erythrocyte surface. Stimulators of eryptosis include increase of cytosolic Ca²⁺ activity ([Ca²⁺]i). The present study tested whether carmustine triggers eryptosis. To this end [Ca²⁺]i was estimated from Fluo3 fluorescence, cell volume from forward scatter, phosphatidylserine exposure from annexin V binding, and hemolysis from hemoglobin release. As a result a 48 h exposure to carmustine (≥25 µM) significantly increased [Ca²⁺]i, decreased forward scatter and increased annexin V binding. The effect on annexin V binding was significantly blunted in the absence of extracellular Ca²⁺. In conclusion, carmustine stimulates eryptosis at least partially by increasing cytosolic Ca²⁺ activity.
亚硝脲类烷化剂卡莫司汀被用作几种恶性肿瘤的化疗药物。该物质触发肿瘤细胞凋亡。卡莫司汀的副作用包括骨髓抑制导致的贫血。至少从理论上讲，贫血部分可能是由于促红细胞生成素的刺激，即红细胞的自杀性死亡，其特征是细胞收缩和细胞膜磷脂酰丝氨酸不对称性的破坏，导致磷脂酰丝氨酸在红细胞表面暴露。促红细胞生成素的刺激物包括细胞浆钙离子活性（[Ca²⁺]i）的增加。本研究测试了卡莫司汀是否引发促红细胞生成素。为此，通过 Fluo3 荧光测定细胞内钙离子浓度 ([Ca²⁺]i)，通过前向散射测定细胞体积，通过 Annexin V 结合测定磷脂酰丝氨酸暴露，通过血红蛋白释放测定溶血。结果显示，卡莫司汀（≥25µM）暴露 48 小时后显著增加 [Ca²⁺]i，降低前向散射，并增加 Annexin V 结合。在不存在细胞外 Ca²⁺的情况下，这种对 Annexin V 结合的影响明显减弱。总之，卡莫司汀至少部分通过增加细胞浆钙离子活性来刺激促红细胞生成素。
