Action of the natural compound esculetin on Ca2+ movement and survival in prostate cancer cells

Esculetin is derived from coumarin and is shown to be the main constituent of the Chinese herb Cortex Fraxini . The molecular paths underlying the action of esculetin are intensively studied. The outcome of esculetin on Ca 2+ concentration ([Ca 2+ ] i ) in prostate cells is unexplored. Fura-2 was used to detect Ca 2+ changes. Death was assessed by using WST-1. At doses of 25-100 mM, esculetin evoked [Ca 2+ ] i raises. This signal was lessened by 15% by exclusion of Ca 2+ . Esculetin (100 μM) induced Mn 2+ entry that implied Ca 2+ influx. Esculetin-evoked Ca 2+ influx was curbed by 50% by nifedipine (1 mM), econazole (0.5 mM) and SKF96365 (5 mM); phorbol 12-myristate 13 acetate (PMA; 1 nM; a protein kinase C [PKC] activator); and GF109203X (2 mM; a PKC inhibitor. In the absence of Ca 2+ , pretreatment with the endoplasmic reticulum (ER) Ca 2+ pump inhibitor thapsigargin (1 mM) eradicated esculetin-induced [Ca 2+ ] i raises. U73122, a phospholipase C (PLC) suppressor got rid of esculetin-caused [Ca 2+ ] i rises. Esculetin (20-70 mM) evoked death which was not restrained by treatment with the Ca 2+ binder BAPTA/AM. In summary, in PC3 cells, esculetin stimulated [Ca 2+ ] i raises by Ca 2+ influx through PKC-sensitive store-operated Ca 2+ entry and PLC-associated ER Ca 2+ discharging. Esculetin provoked Ca 2+ -independent cell death.