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Jue-Long Wang,
Hsin-Ju Chang,
Li-Ling Tseng,
Chun-Peng Liu,
Kam-Chung Lee,
Kang-Ju Chou,
Jin-Shiung Cheng,
Yuk-Keung Lo, Warren Su,
Yee-Ping Law,
Wei-Chung Chen,
Rai-Chi Chan,
Chung-Ren Jan
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ABSTRACT: Nordihydroguaiaretic acid (NDGA) is widely used as a pharmacological tool to inhibit lipoxygenases; however, recent evidence suggests that it increases renal intracellular [Ca2+]i via novel mechanisms. Here the effect of NDGA on Ca2+ signaling in MG63 osteoblastic cells was explored using fura-2 as a Ca2+ indicator. NDGA (2–50 μM) increased [Ca2+]i in a concentration-dependent manner. The signal comprised an initial rise and an elevated phase over a time period of 4 min. Removing extracellular Ca2+ reduced 2–50 μM NDGA-induced signals by 62±2%. After incubation with 50 μM NDGA in Ca2+-free medium for several minutes, addition of 3 mM CaCl2 induced an increase in [Ca2+]i. NDGA (50 μM)-induced [Ca2+]i increases were not changed by pretreatment with 10 μM of verapamil, diltiazem, nifedipine, nimodipine and nicardipine. In Ca2+-free medium, pretreatment with the endoplasmic reticulum Ca2+ pump inhibitor thapsigargin (1 μM) inhibited 50 μM NDGA-induced [Ca2+]i increases by 69±3%. Inhibition of phospholipase C with 2 μM U73122 had little effect on 50 μM NDGA-induced Ca2+ release. Several other lipoxygenase inhibitors had no effect on basal [Ca2+]i. At a concentration that did not increase basal [Ca2+]i, NDGA (1 μM) did not alter 10 μM ATP- or 1 μM thapsigargin-induced [Ca2+]i increases. Alteration of protein kinase C activity with 1 nM phorbol 12-myristate 13-acetate or 2 μM GF 109203X did not affect 50 μM NDGA-induced [Ca2+]i increases. Together, the results show that NDGA increased [Ca2+]i in osteoblasts in a lipoxygenase-independent manner, by releasing stored Ca2+ in a fashion independent of phospholipase C activity, and by causing Ca2+ influx.
Pharmacology & Toxicology 11/2003; 89(6):301 - 305.
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ABSTRACT: The study was undertaken to explore the effect of CP55,940 ((-)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol), a drug commonly used as a CB1/CB2 cannabinoid receptor agonist, on intracellular free Ca2+ levels ([Ca2+]i) in MG63 human osteoblast-like epithelial cells. [Ca2+]i was measured in suspended cells by using the fluorescent dye fura-2 as an indicator. At concentrations between 2-20 microM, CP55,940 increased [Ca2+]i in a concentration-dependent manner with an EC50 of 8 microM. The [Ca2+] signal comprised an initial rise, a slow decay, and a sustained phase. CP55940 (10 microM)-induced [Ca2+]i signal was not altered by 5 microM of two cannabinoid receptor antagonists (AM-251, N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole3-carboxamide; AM-281, 1-(2,4-Dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-4-morpholinyl-1H-pyrazole-3-carboxamide). Extracellular Ca2+ removal decreased the maximum value of the Ca2+ signals by 50%. CP55,940 induced quench of fura-2 fluorescence by Mn2+ (50 microM), suggesting the presence of Ca2+ influx across the plasma membrane. CP55,940 (10 microM)-induced [Ca2+]i increase in Ca(2+)-free medium was inhibited by 84% by pretreatment with 1 microM thapsigargin, an endoplasmic reticulum Ca2+ pump inhibitor. Conversely, pretreatment with 10 microM CP55,940 in Ca(2+)-free medium abolished thapsigargin-induced [Ca2+]i increase. At 1 microM, nifedipine, verapamil, and diltiazem did not alter CP55, 940 (10 microM)-induced [Ca2+]i increase. CP55,940 (20 microM)-induced Ca2+ release was not affected when phospholipase C was inhibited by 2 microM U73122 (1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino) hexyl)-1H-pyrrole-2,5-dione). CP55,940 (20 microM) did not induce acute cell death after incubation for 30 min as assayed by trypan blue exclusion. Collectively, CP55,940 induced significant [Ca2+]i increases in osteoblasts by releasing store Ca2+ from thapsigargin-sensitive stores and by causing Ca2+ entry. The CP55,940's action appears to be independent of stimulation of CB1 cannabinoid receptors.
The Chinese journal of physiology 10/2002; 45(3):95-100. · 0.56 Impact Factor
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Guei Jane Wang,
Lie Chwen Lin,
Chieh Fu Chen,
Jin Shiung Cheng,
Yuk Keung Lo,
Kang Ju Chou,
Kam Chung Lee,
Chun Peng Liu,
Yu Yuan Wu, Warren Su,
Wei Chung Chen,
Chung Ren Jan
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ABSTRACT: The effects of timosaponin A-III (TA-III), from Rhizoma Anemarrhenae, on Ca(2+) mobilization in vascular endothelial cells and smooth muscle cells and on vascular tension have been explored. TA-III increased intracellular Ca(2+) concentrations ([Ca(2+)](i)) in endothelials cells at a concentration larger than 5 microM with an EC(50) of 15 microM, and increased [Ca(2+)](i) in smooth muscle cells at a concentration larger than 1 microM with an EC(50) of 8 microM. Within 5 min, the [Ca(2+)](i) signal was composed of a gradual rise, and the speed of rising depended on the concentration of TA-III. The [Ca(2+)](i) signal was abolished by removing extracellular Ca(2+) and was recovered after reintroduction of Ca(2+). The TA-III-induced [Ca(2+)](i) increases in smooth muscle cells were partly inhibited by 10 microM nifedipine or 50 microM La(3+), but was insensitive to 10 microM verapamil and diltiazem. TA-III (10-100 microM) inhibited 0.3 microM phenylephrine-induced vascular contraction, which was abolished by pretreatment with 100 microM N(omega)-nitro-L-arginine (L-NNA) or by denuding the aorta. TA-III also increased [Ca(2+)](i) in renal tubular cells with an EC(50) of 8 microM. Collectively, the results show for the first time that TA-III causes [Ca(2+)](i) increases in the vascular system. TA-III acted by causing Ca(2+) influx without releasing intracellular Ca(2+). TA-III induced relaxation of phenylephrine-induced vascular contraction via inducing release of nitric oxide from endothelial cells.
Life Sciences 08/2002; 71(9):1081-90. · 2.53 Impact Factor
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ABSTRACT: The anti-breast cancer drug tamoxifen has recently been shown to cause an increase in [Ca(2+)]i in renal tubular cells, breast cells and bladder cells. Because tamoxifen is known to interact with oestrogens leading to modulation of bone metabolism, the present study was aimed at exploring whether tamoxifen could alter Ca(2+) signaling in human osteoblast-like MG63 cells. Cytosolic free Ca(2+) levels were recorded by using the Ca(2+)-sensitive dye fura-2. Tamoxifen induced a sustained [Ca(2+)]i increase at concentrations above 1 microM with an EC(50) of 8 microM. Removal of extracellular Ca(2+) reduced the response by 40%, suggesting that tamoxifen induced both Ca(2+) influx and store Ca(2+) release. Tamoxifen-induced Ca(2+) influx was confirmed as tamoxifen caused Mn(2+) influx-induced quench of fura-2 fluorescence. In Ca(2+)-free medium, pretreatment with 10 microM tamoxifen abolished the [Ca(2+)]i increase induced by 1 microM thapsigargin (an endoplasmic reticulum Ca(2+) pump inhibitor), and by 2 microM carbonylcyanide m-chlorophenylhydrazone (a mitochondrial uncoupler). Conversely, pretreatment with thapsigargin and carbonylcyanide m-chlorophenylhydrazone only reduced 64% of tamoxifen-induced [Ca(2+)]i increases. Addition of 2 microM U73122 to inhibit phospholipase C activity abolished the [Ca(2+)]i increase induced by 1 microM histamine, a phospholipase C-dependent Ca(2+) mobilizer, without affecting 10 microM tamoxifen-induced Ca(2+) release. The [Ca(2+)]i increase induced by 10 microM tamoxifen was not altered by 10 microM of nifedipine, verapamil and diltiazem. Together, the data show that tamoxifen induced a lasting increase in [Ca(2+)]i in human osteoblast-like cells by causing Ca(2+) influx and releasing Ca(2+) from multiple stores in a phospholipase C-independent manner.
Pharmacology & Toxicology 08/2002; 91(1):34-9.
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ABSTRACT: The effect of the oxidant t-butyl hydroperoxide on intracellular free levels of Ca2+ ([Ca2+]i) in PC12 pheochromocytoma cells was examined by using fura-2 as a fluorescent dye. t-Butyl hydroperoxide induced an increase in [Ca2+]i in a concentration-dependent fashion between 50-250 microM with an EC50 of 100 microM. The [Ca2+]i signal consisted of a slow rise and a sustained phase. The response was decreased by 65% by removal of extracellular Ca2+. In Ca(2+)-free medium, pretreatment with 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor) abolished 150 microM t-butyl hydroperoxide-induced [Ca2+]i increase, and conversely, pretreatment with t-butyl hydroperoxide abrogated thapsigargin-induced [Ca2+]i increase. The 150 microM t-butyl hydroperoxide-induced [Ca2+]i increase in Ca2+ medium was reduced by 42 +/- 5% by pretreatment with 0.1 microM nicardipine but not by 10 microM verapamil, nifedipine, nimodipine or diltiazem, or by 50 microM La3+ or Ni2+. Pretreatment with 10 microM t-butyl hydroperoxide for 40 min did not affect 10 microM ATP-induced [Ca2+]i increase. Together, the results show that t-butyl hydroperoxide induced significant [Ca2+]i increase in PC12 cells by causing store Ca2+ release from the thapsigargin-sensitive endoplasmic reticulum pool in an inositol 1,4,5-trisphosphate-independent manner and by inducing Ca2+ influx via a nicardipine-sensitive pathway.
The Chinese journal of physiology 07/2002; 45(2):51-6. · 0.56 Impact Factor
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ABSTRACT: The effect of five lignans isolated from Hernandia nymphaeifolia on estrogenic compounds (17beta-estradiol, tamoxifen and clomiphene)-induced Ca(2+) mobilization in human neutrophils was investigated. The five lignans were epi-yangambin, epi-magnolin, epi-aschantin, deoxypodophyllotoxin and yatein. In Ca(2+)-containing medium, the lignans (50-100 microM) inhibited 10 microM 17beta-estradiol- and 5 microM tamoxifen-induced increases in intracellular free Ca(2+) levels ([Ca(2+)](i)) without changing 25 microM clomiphene-induced [Ca(2+)](i) increase. 17beta-estradiol and tamoxifen increased [Ca(2+)](i) by causing Ca(2+) influx and Ca(2+) release because their responses were partly reduced by removing extracellular Ca(2+). In contrast, clomiphene solely induced Ca(2+) release. The effect of the lignans on these two Ca(2+) movement pathways underlying 17beta-estradiol- and tamoxifen-induced [Ca(2+)](i) increases was explored. All the lignans (50-100 microM) inhibited 10 microM 17beta-estradiol-and 5 microM tamoxifen-induced Ca(2+) release, and 17beta-estradiol-induced Ca(2+) influx. However, only 100 microM epi-aschantin was able to reduce tamoxifen-induced Ca(2+) influx while the other lignans had no effect. Collectively, this study shows that the lignans altered estrogenic compounds-induced Ca(2+) signaling in human neutrophils in a multiple manner.
Life Sciences 06/2002; 70(26):3109-21. · 2.53 Impact Factor
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Yu-Ying Chao,
Ih-Sheng Chen,
Jwu-Lai Yeh,
Jih-Jung Chen,
Ying-Chin Ko,
Jin-Shiung Cheng,
Chun-Peng Liu,
Yuk-Keung Lo, Warren Su,
Kang-Ju Chou,
Wei-Chung Chen,
Chung-Ren Jan
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ABSTRACT: The effect of five lignans, epi-aschantin, epi-magnolin, epi-yangambin, deoxypodophyllotoxin and yatein, isolated from Hernandia nymphaeifolia on Ca(2+) signaling in Madin-Darby canine kidney cells was examined using fura-2 as a Ca(2+) indicator. These lignans at concentrations between 10 and 100 microM increased [Ca(2+)](i) in a concentration-dependent manner. Removal of extracellular Ca(2+) abolished the Ca(2+) signals evoked by 50 microM of the lignans. La(3+)(50 microM) abolished the Ca(2+) signals induced by 100 microM of epi-aschantin, epi-magnolin and epi-yangambin, and 20 microM deoxypodophyllotoxin, but inhibited by 60% 50 microM yatein-induced responses. All five lignans (50-100 microM) inhibited by 42-65% thapsigargin-induced capacitative Ca(2+) entry, and inhibited by 23-61% thapsigargin-induced intracellular Ca(2+) release. Epi-yangambin (100 microM), epi-magnolin (100 microM), and epi-aschantin (100 microM) inhibited by 8-38% 10 microM ATP-induced Ca(2+) release. Trypan blue exclusion revealed that incubation with deoxypodophyllotoxin or yatein (but not the other lignans) decreased cell viability in a concentration-dependent manner. Together, the results suggest that, in renal tubular cells, these lignans exert multiple actions on Ca(2+) signaling. They caused Ca(2+) influx but reduced thapsigargin-induced capacitative Ca(2+) entry and also thapsigargin- and ATP-induced Ca(2+) release. Additionally, deoxypodophyllotoxin and yatein may be cytotoxic.
European Journal of Pharmacology 06/2002; 443(1-3):31-8. · 2.52 Impact Factor
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Warren Su,
Li-Ling Tseng,
Muh-Chiou Lin,
Hsin-Ju Chang,
Kam-Chung Lee,
Kang-Ju Chou,
Yuk-Keung Lo,
Jin-Shiung Cheng,
Hong-Tai Chang,
Jue-Long Wang,
Chun-Peng Liu,
Wei-Chung Chen,
Chung-Ren Jan
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ABSTRACT: The effect of nordihydroguaiaretic acid (NDGA) on Ca(2+) signaling in C6 glioma cells has been investigated. NDGA (5-100 microM) increased [Ca(2+)]i concentration-dependently. The [Ca(2+)]i increase comprised an initial rise and an elevated phase over a time period of 4 min. Removal of extracellular Ca(2+) reduced NDGA-induced [Ca(2+)]i signals by 52+/-2%. After incubation of cells with NDGA in Ca(2+)-free medium for 4 min, addition of 3 mM CaCl2 induced a concentration-dependent increase in [Ca(2+)]i. NDGA (100 microM)-induced [Ca(2+)]i increases in Ca(2+)-containing medium was not changed by pretreatment with 10 microM nifedipine or verapamil. In Ca(2+)-free medium, pretreatment with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin (1 microM) abolished 100 microM NDGA-induced [Ca(2+)]i increases. Inhibition of phospholipase C with 2 microM U73122 had little effect on 100 microM NDGA-induced Ca(2+) release. Several other lipoxygenase inhibitors had no effect on basal [Ca(2+)]i. Collectively, the results suggest that NDGA increased [Ca(2+)]i in glioma cells in a lipoxygenase-independent manner, by releasing Ca(2+) from the endoplasmic reticulum in a manner independent of phospholipase C activity and by causing Ca(2+) influx.
Neurochemistry International 04/2002; 40(3):249-54. · 2.86 Impact Factor
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ABSTRACT: The study was undertaken to explore the effect of CP55,940 ((-)-cis-3-[2-Hydroxy4-(1,1-dimethylheptyl) phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol), a drug commonly used as a CB1/CB2 cannabinoid receptor agonist, on intracellular free Ca2+ levels ([Ca2+]i) in several cell types [Ca2+]i was measured in suspended cells by using the fluorescent dye fura-2 as an indicator. At concentrations between 1-50 microM, CP55,940 increased [Ca2+]i in a concentration-dependent manner with an EC50 of 8 microM. The [Ca2+]i signal comprised an initial rise, a slow decay, and a sustained phase. CP55940 (10 microM)-induced (Ca2+]i signal was not altered by 5 microM of two cannabinoid receptor antagonists (AM-251, N-(Piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide; AM-281, 1-(2,4-Dichlorophenyl)-5-(4-iodophenyl)-4-m3thyl-N-4-morpholinyl-1H-pyrazole-3-carboxamide). Extracellular Ca2+ removal decreased the maximum value of the Ca2+ signals by 50%. CPS5,940 (10 microM)-induced [Ca2+]i increase in Ca2+-free medium was inhibited by 80% by pretreatment with 1 microM thapsigargin, an endoplasmic reticulum Ca2+ pump inhibitor. Conversely, pretreatment with 10 microM CP55,940 in Ca2+-free medium for 6 min abolished thapsigargin-induced [Ca2+]i increase. Nifedipine (10 microM) and verapamil (10 microM) did not alter CP55,940 (10 microM)-induced [Ca2+]i increase. CP55, 940 (10 microM)-induced Ca2+ release was not affected when phospholipase C was inhibited by 2 microM U73122 (1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione). CP55,940 (5 microM) also increased [Ca22+] in Madin-Darby canine kidney cells, MG63 human osteosarcoma cells, and IMR-32 neuroblastoma cells. Collectively, CP,55940 induced significant [Ca2+]i increases in several cell types by releasing store Ca2+ from thapsigargin-sensitive pools and by causing Ca2+ entry. The CP55,940's action appears to be dissociated from stimulation of cannabinoid receptors
The Chinese journal of physiology 04/2002; 45(1):33-9. · 0.56 Impact Factor
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ABSTRACT: The effects of triethyltin on Ca2+ mobilization in human PC3 prostate cancer cells have been explored. Triethyltin increased [Ca2+]i at concentrations larger than 3 microM with an EC50 of 30 microM. Within 5 min, the [Ca2+]i signal was composed of a gradual rise and a sustained phase. The [Ca2+]i signal was reduced by half by removing extracellular Ca2+. The triethyltin-induced [Ca2+]i increases were inhibited by 40% by 10 microM nifedipine, nimodipine and nicardipine, but were not affected by 10 microM of verapamil or diltiazem. In Ca2+-free medium, pretreatment with thapsigargin (1 microM), an endoplasmic reticulum Ca+ pump inhibitor, reduced 200 microM triethyltin-induced Ca+ increases by 50%. Pretreatment with U73122 (2 microM) to inhibit phospholipase C did not alter 200 microM triethyltin-induced [Ca2+]i increases. Incubation with triethyltin at a concentration that did not increase [Ca2+]i (1 microM) in Ca2+-containing medium for 3 min potentiated ATP (10 microM)- or bradykinin (1 microLM)-induced [Ca2+]i increases by 41 +/- 3% and 51 +/- 2%, respectively. Collectively, this study shows that the environmental toxicant triethyltin altered Ca2+ handling in PC3 prostate cancer cells in a concentration-dependent manner: at higher concentrations it increased basal [Ca2+]i; and at lower concentrations it potentiated agonists-induced [Ca2+]i increases.
Life Sciences 03/2002; 70(11):1337-45. · 2.53 Impact Factor
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Yu-Ying Chao, Warren Su,
Chung-Ren Jan,
Ying-Chin Ko,
Jih-Jung Chen,
Jin-Shiung Cheng,
Chun-Peng Liu,
Yuk-Keung Lo,
Kang-Ju Chou,
Kam-Chung Lee,
Wei-Chung Chen,
Ih-Sheng Chen
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ABSTRACT: The effects of five lignans (epi-aschantin, epi-magnolin, epi-yangambin, deoxypodophyllotoxin, yatein) isolated from Hernandia nymphaeifolia (Presl.) Kubitzki (Hernandiaceae) on intracellular Ca2+ levels ([Ca2+]i) in human neutrophils were investigated by using fura-2 as a fluorescent probe. In both Ca2+-containing and Ca2+-free media, the lignans (50-100 microM) did not alter basal [Ca2+]i but inhibited the [Ca2+]i increase induced by platelet activating factor (PAF, 10 microM), leukotriene B4 (LTB4, 0.2 microM), and thapsigargin (1 microM) to different extents. In Ca2+-free medium, after depleting stores of Ca2+ with PAF, LTB4 or thapsigargin, addition of 3 mM Ca2+ induced Ca2+ influx. Each of the lignans (50-100 microM) caused 39-89% inhibition of PAF-induced Ca2+ influx; whereas only epi-aschantin was able to inhibit LTB4- and thapsigargin-induced Ca2+ influx by 54-79%. Together, the results suggest that in human neutrophils, these lignans did not alter basal [Ca2+]i but inhibited Ca2+ movement induced by Ca2+ mobilizing agents.
Archive für Toxikologie 02/2002; 75(11-12):695-702. · 4.67 Impact Factor
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Hong-Tai Chang,
Jong-Khing Huang,
Jue-Long Wang,
Jin-Shiung Cheng,
Kam-Chung Lee,
Yuk-Keung Lo,
Chun-Pin Liu,
Kang-Ju Chou,
Wei-Chung Chen, Warren Su,
Yee-Ping Law,
Chung-Ren Jan
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ABSTRACT: Tamoxifen has been shown to increase cytoplasmic free Ca2+ levels [Ca2+]i in renal tubular cells and bladder cancer cells, and to after Ca2+ signaling in MCF-7 breast cancer cells. The present study examined the effect of tamoxifen on [Ca2+], in ZR-75-1 human breast cancer cells using fura-2 as an indicator. Tamoxifen increased [Ca2+]i at a concentration above 2 microM with an EC50 of 5 microM. Removing extracellular Ca2+ reduced the response by 48+/-2%. In Ca2+-free medium, after tamoxifen-induced [Ca2+]i increased had returned to baseline, adding 3 mM Ca2+ increased [Ca2+]i in a concentration-dependent manner. Further, pretreatment with 10 microM tamoxifen abolished the [Ca2+]i increase induced by 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor); and conversely, pretreatment with thapsigargin prevented tamoxifen from releasing more Ca2+. Tamoxifen (10 microM)-induced Ca2+ release was not changed by inhibiting phospholipase C activity with 2 microM U73122. Trypan blue exclusion assay revealed that tamoxifen (1-10 microM) did not alter viability after 1 min of incubation, but killed 10% of cells after 3-10 min of incubation. Together, this study shows that tamoxifen (>2 microM) induced a significant, immediate increase in [Ca2+]i in ZR-75-1 breast cancer cells. Tamoxifen acted by releasing Ca2+ from the endoplasmic reticulum Ca2+ stores in a manner independent of phospholipase C activity, and by inducing Ca2+ entry from extracellular medium. Tamoxifen may be of mild cytotoxicity after acute exposure.
Breast Cancer Research and Treatment 02/2002; 71(2):125-31. · 4.43 Impact Factor
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Yu-Ying Chao, Warren Su,
Chung-Ren Jan,
Ying-Chin Ko,
Jih-Jung Chen,
Jin-Shiung Cheng,
Chun-Peng Liu,
Yuk-Keung Lo,
Kang-Ju Chou,
Kam-Chung Lee,
Wei-Chung Chen,
Ih-Sheng Chen
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ABSTRACT: The effects of five lignans (epi-aschantin, epi-magnolin, epi-yangambin, deoxypodophyllotoxin, yatein) isolated from Hernandia nymphaeifolia (Presl.) Kubitzki (Hernandiaceae) on intracellular Ca 2+ levels ([Ca 2+] i) in human neutrophils were investigated by using fura-2 as a fluorescent probe. In both Ca 2+-containing and Ca 2+-free media, the lignans (50–100M) did not alter basal [Ca 2+] i but inhibited the [Ca 2+] i increase induced by platelet activating factor (PAF, 10M), leukotriene B 4 (LTB 4, 0.2M), and thapsigargin (1M) to different extents. In Ca 2+-free medium, after depleting stores of Ca 2+ with PAF, LTB 4 or thapsigargin, addition of 3mM Ca 2+ induced Ca 2+ influx. Each of the lignans (50–100M) caused 39–89% inhibition of PAF-induced Ca 2+ influx; whereas only epi-aschantin was able to inhibit LTB 4- and thapsigargin-induced Ca 2+ influx by 54–79%. Together, the results suggest that in human neutrophils, these lignans did not alter basal [Ca 2+] i but inhibited Ca 2+ movement induced by Ca 2+ mobilizing agents.
Archive für Toxikologie 12/2001; 75(11):695-702. · 4.67 Impact Factor
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Jin‐Shiung Cheng,
Kang‐Ju Chou,
Jue‐Long Wang,
Kam‐Chung Lee,
Li‐Ling Tseng,
Kwong‐Yui Tang,
Jong‐Khing Huang,
Hong‐Tai Chang, Warren Su,
Yee‐Ping Law,
Chung‐Ren Jan
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ABSTRACT: SUMMARY1. The effects of the antianginal drug fendiline (N-[3,3-diphenylpropyl]-α-methyl-benzylamine) on intracellular free Ca2+ levels ([Ca2+]i) in Chang liver cells were evaluated using fura-2 as a fluorescent Ca2+ indicator.2. Fendiline (1–100 μmol/L) increased [Ca2+]i in a concentration-dependent manner, with an EC50 of 25 μmol/L.3. The [Ca2+]i response was composed of an initial rise and a slow decay to a sustained phase. Removal of extracellular Ca2+ partly reduced the [Ca2+]i signals.4. Fendiline (10 μmol/L)-induced release of intracellular Ca2+ was reduced by 65% following pretreatment with 1 μmol/L thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor) to deplete Ca2+ stored in the endoplasmic reticulum.5. After pretreatment with 10 μmol/L fendiline in Ca2+-free medium for several minutes, addition of 3 mmol/L Ca2+ induced an increase in [Ca2+]i of a magnitude four-fold greater than control. This increase in [Ca2+]i was not reduced by 10 μmol/L SKF96365, econazole, nifedipine or verapamil.6. Fendiline (10 μmol/L)-induced release of intracellular Ca2+ was not altered by inhibition of phospholipase C with 2 μmol/L 1-(6-((17β-3-methoxyestra-1,3,5(10)-trien-17-yl)amino) hexyl)-1H-pyrrole-2,5-dione (U73122).7. The results of the present study show that fendiline induces an increase in [Ca2+]i in Chang liver cells by releasing stored Ca2+ in an inositol 1,4,5-trisphosphate-independent manner and by causing extracellular Ca2+ influx.
Clinical and Experimental Pharmacology and Physiology 09/2001; 28(9):729 - 733. · 1.85 Impact Factor
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Wei-Chung Chen,
Muh-Chiou Lin,
Kang-Ju Chou,
Hua-Chang Fang,
Chun-Peng Liu,
Jin-Shiung Cheng,
Yuk-Keung Lo,
Kim-Chung Lee,
Jue-Long Wang, Warren Su,
Yee-Ping Law,
Chung-Ren Jan
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ABSTRACT: The effect of oleamide, a sleep-inducing endogenous lipid in animal models, on intracellular free levels of Ca2+ ([Ca2+]i) in Madin-Darby renal tubular cells was examined using fura-2 as a fluorescent dye. Oleamide (5–50 μM) increased [Ca2+]i in a concentration-dependent fashion with an EC50 value of 20 μM. The [Ca2+]i signal comprised an initial rise and an elevated phase and was reduced by removing extracellular Ca2+ by 50%. After pretreatment with 5–50 μM oleamide in Ca2+-free medium, addition of 3 mM Ca2+ increased [Ca2+]i in a manner dependent on the concentration of oleamide. In Ca2+-free medium, pretreatment with thapsigargin (1 μM), an endoplasmic reticulum Ca2+ pump inhibitor, abolished [Ca2+]i increases induced by 20 μM oleamide; conversely, pretreatment with 20 μM oleamide reduced 1 μM thapsigargin-induced [Ca2+]i increases by 50%. Suppression of the activity of phospholipase C with 2 μM U73122 abolished 20 μM oleamide-induced Ca2+ release. Collectively, these data demonstrate that oleamide induced significant [Ca2+]i increases in renal tubular cells by a phospholipase C-dependent release of Ca2+ from thapsigargin-sensitive stores and by inducing Ca2+ entry via store-operated Ca2+ entry. Drug Dev. Res. 54:40–44, 2001. © 2001 Wiley-Liss, Inc.
Drug Development Research 08/2001; 54(1):40 - 44. · 1.19 Impact Factor
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ABSTRACT: Riluzole is an effective neuroprotective drug. Its effect on intracellular free Ca2+ levels ([Ca2+]i) has not been explored. This study examined the effect of riluzole on [Ca2+]i in IMR32 neuroblastoma cells using fura-2 as a Ca2+ probe. Riluzole 0.1-1 mM increased [Ca2+]i in a concentration-dependent manner. Removal of extracellular Ca2+ inhibited the response by 52LJ%. The [Ca2+]i increase induced by 0.2 mM riluzole was unaltered by 0.1 mM La3+ or 10 M verapamil, but was inhibited by 51dž% by 10 M nifedipine. In Ca2+-free medium, pretreatment with 1 M thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor) reduced the 0.2 mM riluzole-induced Ca2+ release by 44Dž%; this reduction was augmented to 66LJ% by additionally depleting the Ca2+ stores in the Golgi complex with 50 M brefeldin A. Inhibition of inositol 1,4,5-trisphosphate formation by 2 M U73122, a phospholipase C inhibitor, did not affect Ca2+ release induced by 0.2 M riluzole. It was concluded that the neuroprotective agent riluzole increased [Ca2+]i in IMR32 neuroblastoma cells concentration-dependently by releasing Ca2+ from multiple stores in an inositol 1,4,5-trisphosphate-independent manner and also by inducing nifedipine-sensitive Ca2+ influx.
Archive für Toxikologie 05/2001; 75(4):214-220. · 4.67 Impact Factor
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Kam-Chung Lee,
Hong-Tai Chang,
Kang-Ju Chou,
Kwong-Yui Tang,
Jue-Long Wang,
Yuk-Keung Lo,
Jong-Khing Huang,
Wei-Chung Chen, Warren Su,
Yee-Ping Law,
Chung-Ren Jan
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ABSTRACT: The effect of histamine on intracellular free Ca 2+levels ([Ca 2+] i) in PC3 human prostate cancer cells and the underlying mechanism were evaluated using fura-2 as a Ca 2+dye. Histamine at concentrations between 0.1 and 50 μM increased [Ca 2+] iin a concentration-dependent manner with an EC 50value of 1 μM. The [Ca 2+] iresponse comprised an initial rise and a slow decay, which returned to baseline within 3 min. Extracellular Ca 2+removal inhibited 50% of the [Ca 2+] isignal. In the absence of extracellular Ca 2+, after cells were treated with 1 μM thapsigargin (an endoplasmic reticulum Ca 2+pump inhibitor), 10 μM histamine did not increase [Ca 2+] i. After pretreatment with 10 μM histamine in a Ca 2+-free medium for several minutes, addition of 3 mM Ca 2+induced [Ca 2+] iincreases. Histamine (10 μM)-induced intracellular Ca 2+release was abolished by inhibiting phospholipase C with 2 μM 1-(6-((17 β-3- methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione (U73122), and by 10 μM pyrilamine but was not altered by 50 μM cimetidine. Collectively, the present study shows that histamine induced [Ca 2+] itransients in PC3 human prostate cancer cells by stimulating H1 histamine receptors leading to Ca 2+release from the endoplasmic reticulum in an inositol 1,4,5-trisphosphate-dependent manner, and by inducing Ca 2+entry.
Pharmacological Research.
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Yuk-Keung Lo,
Kwong-Yui Tang,
Wen-Neng Chang,
Cheng-Hsien Lu,
Jin-Shiung Cheng,
Kam-Chung Lee,
Kang-Ju Chou,
Chun-Peng Liu,
Wei-Chung Chen, Warren Su,
Yee-Ping Law,
Chung-Ren Jan
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ABSTRACT: The effect of oleamide, a sleep-inducing endogenous lipid in animal models, on intracellular free levels of Ca2+ ([Ca2+]i) in non-excitable and excitable cells was examined by using fura-2 as a fluorescent dye. [Ca2+]i in pheochromocytoma cells, renal tubular cells, osteoblast-like cells, and bladder cancer cells were increased on stimulation of 50 μM oleamide. The response in human bladder cancer cells (T24) was the greatest and was further explored. Oleamide (10–100 μM) increased [Ca2+]i in a concentration-dependent fashion with an EC50 of 50 μM. The [Ca2+]i signal comprised an initial rise and a sustained plateau and was reduced by removing extracellular Ca2+ by 85 ± 5%. After pre-treatment with 10–100 μM oleamide in Ca2+-free medium, addition of 3 mM Ca2+ increased [Ca2+]i in a manner dependent on the concentration of oleamide. The [Ca2+]i increase induced by 50 μM oleamide was reduced by 100 μM La3+ by 40%, but was not altered by 10 μM nifedipine, 10 μM verapamil, and 50 μM Ni2+. In Ca2+-free medium, pre-treatment with thapsigargin (1 μM), an endoplasmic reticulum Ca2+ pump inhibitor, abolished 50 μM oleamide-induced [Ca2+]i increases; conversely, pretreatment with 50 μM oleamide reduced 1 μM thapsigargin-induced [Ca2+]i increases by 50 ± 3%. Suppression of the activity of phospholipase C with 2 μM U73122 failed to alter 50 μM oleamide-induced Ca2+ release. Linoleamide (10–100 μM), another sleep-inducing lipid with a structure similar to that of oleamide, also induced an increase in [Ca2+]i. Together, it was shown that oleamide induced significant [Ca2+]i increases in cells by a phospholipase C-independent release of Ca2+ from thapsigargin-sensitive stores and by inducing Ca2+ entry.
Biochemical Pharmacology. 62(10):1363-1369.
