Effect of MK-886 on Ca2+ level and viability in PC3 human prostate cancer cells.
3-[1-(p-chlorobenzyl)-5-(isopropyl)-3-tert-butylthioindol-2-yl]-2, 2-dimethylpropanoic acid (MK-886) is widely used for inhibition of leucotriene synthesis in in vitro studies, however, many of its other effects have been reported. The present study investigated the effect of MK-886 on cytosolic-free Ca(2+) concentrations ([Ca(2+)](i)) and viability in human PC3 prostate cancer cells. [Ca(2+)](i) in suspended cells was measured by using fura-2. MK-886 at concentrations of 1 microM and above increased [Ca(2+)](i) in a concentration-dependent manner with an EC(50) value of 20 microM. The Ca(2+) signal was reduced partly by removing extracellular Ca(2+). MK-886 evoked Mn(2+) quenching of fura-2 fluorescence, implicating Ca(2+) entry. MK-886-induced Ca(2+) influx was inhibited by store-operated Ca(2+) entry inhibitors nifedipine, econazole and SKF96365. In Ca(2+)-free medium, after pre-treatment with 10 microM MK-886, 1 microM thapsigargin (an endoplasmic reticulum Ca(2+) pump inhibitor)-induced [Ca(2+)](i) rises were abolished; and conversely, thapsigargin pre-treatment abolished MK-886-induced [Ca(2+)](i) rises. Inhibition of phospholipase C with U73122 did not alter MK-886-induced [Ca(2+)](i) rises. MK-886 at concentrations of 1-100 microM concentration-dependently decreased cell viability with an IC(50) value of 60 microM. The cytotoxic effect of MK-886 was not inhibited by pre-chelating cytosolic Ca(2+) with BAPTA/AM. Together, in PC3 cells, MK-886 induced [Ca(2+)](i) rises by causing phospholipase C-independent Ca(2+) release from the endoplasmic reticulum; and Ca(2+) influx via store-operated Ca(2+) channels. Independently, MK-886 was cytotoxic to cells in a Ca(2+)-independent manner.
Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan.
Jong-Khing
JK
Huang
Chorng-Chih
CC
Huang
Ti
T
Lu
Hong-Tai
HT
Chang
Ko-Long
KL
Lin
Jeng-Yu
JY
Tsai
Wei-Chuan
WC
Liao
Jau-Min
JM
Chien
Chung-Ren
CR
Jan
D001094:Arachidonate 5-Lipoxygenase / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002413:Cations, Divalent; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004963:Estrenes / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D016859:Lipoxygenase Inhibitors; D008297:Male; D011471:Prostatic Neoplasms; D011760:Pyrrolidinones / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism; D002722:Chlorobenzenes
D001094:Arachidonate 5-Lipoxygenase; D002118:Calcium; D002121:Calcium Channel Blockers; D002413:Cations, Divalent; D004963:Estrenes; D007211:Indoles; D016859:Lipoxygenase Inhibitors; D011760:Pyrrolidinones; D019284:Thapsigargin; D010738:Type C Phospholipases; C060893:MK-886; D002722:Chlorobenzenes; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione