Nordihydroguaiaretic acid-induced Ca2+ handling and cytotoxicity in human prostate cancer cells.
The effect of nordihydroguaiaretic acid (NDGA), a compound commonly used as a lipoxygenases inhibitor, on intracellular free Ca2+ levels ([Ca2+]i) in PC3 human prostate cancer cells was investigated. [Ca2+]i was measured by using the Ca2+ -sensitive dye fura-2. NDGA increased [Ca2+]i in a concentration-dependent manner with an EC50 of 30 microM. The Ca2+ signal comprised a gradual and sustained increase. Removal of extracellular Ca2+ partly decreased the NDGA-induced [Ca2+]i increase, suggesting that the Ca2+ signal was due to both extracellular Ca2+ influx and intracellular Ca2+ release. NDGA-induced Ca2+ influx was independently confirmed by measuring NDGA-induced Mn2+ -coupled quench of fura-2 fluorescence. The NDGA-induced Ca2+ influx was not affected by L-type Ca2+ channel blockers. In Ca2+ -free medium, the NDGA-induced [Ca2+]i increase was abolished by pretreatment with 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor), and conversely, pretreatment with NDGA abolished thapsigargin-induced [Ca2+]i increase. NDGA-induced intracellular Ca2+ release was not altered by inhibition of phospholipase C. Overnight treatment with 20-50 microM NDGA inhibited cell proliferation rate in a concentration-dependent manner. Several other lipoxygenases inhibitors did not alter [Ca2+]i. Collectively, this study shows that in prostate cells, NDGA induced a [Ca2+]i increase via releasing stored Ca2+ from the endoplasmic reticulum in a manner independent of phospholipase C activity, and by causing Ca2+ influx. NDGA also caused cytotoxicity at higher concentrations.
Huang
Jong-Khing
JK
Department of Surgery, Kaohsiung Veterans General Hospital, Taiwan 813.
Chen
Wei-Chuan
WC
Huang
Chun-Jen
CJ
Hsu
Shu-Shong
SS
Chen
Jin-Shyr
JS
Cheng
He-Hsiung
HH
Chang
Hong-Tai
HT
Jiann
Bang-Ping
BP
Jan
Chung-Ren
CR
D000970:Antineoplastic Agents; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003124:Colorimetry; D005456:Fluorescent Dyes; D016257:Fura-2; D006801:Humans; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology*; D008297:Male; D009637:Masoprocol / Q000494:pharmacology*; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D012996:Solutions; D010738:Type C Phospholipases / Q000378:metabolism
D000970:Antineoplastic Agents; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D005456:Fluorescent Dyes; D016859:Lipoxygenase Inhibitors; D012996:Solutions; D009637:Masoprocol; D010738:Type C Phospholipases; D002118:Calcium; D016257:Fura-2