Action of the natural compound esculetin on Ca2+ movement and survival in prostate cancer cells
Abstract 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 Ca2+ concentration ([Ca2+]i) in prostate cells is unexplored. Fura-2 was used to detect Ca2+ changes. Death was assessed by using WST-1. At doses of 25-100 mM, esculetin evoked [Ca2+]i raises. This signal was lessened by 15% by exclusion of Ca2+. Esculetin (100 μM) induced Mn2+ entry that implied Ca2+ influx. Esculetin-evoked Ca2+ 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 Ca2+, pretreatment with the endoplasmic reticulum (ER) Ca2+ pump inhibitor thapsigargin (1 mM) eradicated esculetin-induced [Ca2+]i raises. U73122, a phospholipase C (PLC) suppressor got rid of esculetin-caused [Ca2+]i rises. Esculetin (20-70 mM) evoked death which was not restrained by treatment with the Ca2+ binder BAPTA/AM. In summary, in PC3 cells, esculetin stimulated [Ca2+]i raises by Ca2+ influx through PKC-sensitive store-operated Ca2+ entry and PLC-associated ER Ca2+ discharging. Esculetin provoked Ca2+-independent cell death.