Effect of Methoxsalen on Ca²âº Homeostasis and Viability in Human Osteosarcoma Cells.

Methoxsalen is a natural compound found in many seed plants. The effect of methoxsalen on Ca²âº- related physiology in human osteosarcoma is unclear. This study investigated the effect of methoxsalen on cytosolic free Ca²âº concentrations ([Ca²âº]i) in MG63 human osteosarcoma cells. Methoxsalen induced [Ca²âº]i rises concentration-dependently. Methoxsalen-induced Ca²âº entry was confirmed by Mn²âº-induced quench of fura-2 fluorescence. This Ca²âº entry was suppressed by nifedipine, econazole, and SKF96365. In Ca²âº-free medium, incubation with the endoplasmic reticulum Ca²âº pump inhibitor 2,5-di-tert-butylhydroquinone (BHQ) inhibited methoxsalen-evoked [Ca²âº]i rises by 96%. In contrast, incubation with methoxsalen abolished BHQ-evoked [Ca²âº]i rises. Inhibition of phospholipase C (PLC) with U73122 abolished methoxsalen-induced [Ca²âº]i rises. Methoxsalen was cytotoxic at 300-700 µM in a concentration-dependent fashion. Chelating cytosolic Ca²âº with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid/acetoxymethyl ester (BAPTA/AM) did not prevent methoxsalen-induced cytotoxicity. Collectively, our data suggest that in MG63 cells, methoxsalen induced [Ca²âº]i rises by evoking PLC-dependent Ca²âº release from the endoplasmic reticulum, and Ca²âº entry via store-operated Ca²âº entry. Methoxsalen also induced Ca²âº- disassociated cell death.

Rise of [Ca²âº]i and apoptosis induced by M-3M3FBS in SCM1 human gastric cancer cells.

M-3M3FBS (2,4,6-trimethyl-N-(meta-3-trifluoromethyl-phenyl)-benzenesulfonamide is a presumed phospholipase C activator which induced Ca²âº movement and apoptosis in different cell models. How- ever, the effect of m-3M3FBS on cytosolic free Ca²âº concentrations ([Ca²âº]i) and apoptosis in SCM1 human gastric cancer cells is unclear. This study explored whether m-3M3FBS elevated basal [Ca²âº]i levels in suspended cells by using fura-2 as a Ca²âº-sensitive fluorescent dye. M-3M3FBS at concentrations between 5-50 µM increased [Ca²âº]i in a concentration-dependent manner. The Ca²âº signal was reduced by half by removing extracellular Ca²âº. M-3M3FBS-induced Ca²âº influx was inhibited by nifedipine, econazole, SK&F96365, aristolochic acid, and GF109203X. In Ca²âº-free medium, 50 µM m-3M3FBS pretreatment inhibited the [Ca²âº]i rise induced by the endoplasmic reticulum Ca²âº pump inhibitor thapsigargin. Conversely, pretreatment with thapsigargin partly reduced m-3M3FBS-induced [Ca²âº]i rise. Suppression of inositol 1,4,5-trisphosphate production with U73122 did not change m-3M3FBS- induced [Ca²âº]i rise. At concentrations between 25 and 50 µM m-3M3FBS killed cells in a concentration- dependent manner. The cytotoxic effect of m-3M3FBS was not reversed by prechelating cytosolic Ca²âº with acetoxy-methyl ester of bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA/AM). Annexin V/propidium iodide staining data suggest that m-3M3FBS induced apoptosis at 25 and 50 µM. M-3M3FBS also increased levels of superoxide. Together, in human gastric cancer cells, m-3M3FBS induced a [Ca²âº]i rise by inducing phospholipase C-independent Ca²âº release from the endoplasmic reticulum and Ca²âº entry via protein kinase C-sensitive store-operated Ca²âº channels. M-3M3FBS induced cell death that might involve apoptosis via reactive oxygen species production.

M-3M3FBS-induced Ca² ⁺ movement and apoptosis in HA59T human hepatoma cells.

The effect of 2,4,6-trimethyl-N-(meta-3-trifluoromethyl-phenyl)-benzenesulfonamide (m-3M3FBS), a presumed phospholipase C activator, on cytosolic free Ca² ⁺ concentrations ([Ca² ⁺ ]i ) in HA59T human hepatoma cells is unclear. This study explored whether m-3M3FBS elevated basal [Ca² ⁺ ]i levels in suspended cells by using fura-2 as a Ca² ⁺ -sensitive fluorescent dye. M-3M3FBS at concentrations of 10- 50 µM increased [Ca² ⁺ ]i in a concentration-dependent fashion. The Ca² ⁺ signal was reduced partly by removing extracellular Ca² ⁺ . M-3M3FBS-induced Ca² ⁺ influx was inhibited by nifedipine, econazole, SK&F96365, aristolochic acid, and GF109203X. In Ca² ⁺ -free medium, 50 µM m-3M3FBS pretreatment inhibited the [Ca² ⁺ ]i rise induced by the endoplasmic reticulum Ca² ⁺ pump inhibitor thapsigargin. Conversely, pretreatment with thapsigargin partly reduced m-3M3FBS-induced [Ca² ⁺ ]i rise. Inhibition of inositol 1,4,5-trisphosphate formation with U73122 did not alter m-3M3FBS-induced [Ca² ⁺ ]i rise. At concentrations between 10 and 40 µM m-3M3FBS killed cells in a concentration-dependent manner. The cytotoxic effect of m-3M3FBS was not reversed by prechelating cytosolic Ca² ⁺ with 1,2-bis(2- aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Annexin V/propidium iodide staining data suggest that m-3M3FBS induced apoptosis in a concentration-dependent manner. M-3M3FBS also increased levels of reactive oxygen species. Together, in human hepatoma cells, m-3M3FBS induced a [Ca² ⁺ ]i rise by inducing phospholipase C-independent Ca² ⁺ release from the endoplasmic reticulum and Ca² ⁺ entry via protein kinase C-sensitive store-operated Ca² ⁺ channels. M-3M3FBS induced cell death that might involve apoptosis via mitochondrial pathways.

Effect of the environmental pollutant bisphenol A dimethacylate (BAD) on Ca2+ movement and viability in OC2 human oral cancer cells.

The environmental pollutant bisphenol A dimethacylate (BAD) has been used as a dental composite. The effect of BAD on cytosolic Ca(2+) concentrations ([Ca(2+)]i) and viability in OC2 human oral cancer cells was explored. The Ca(2+)-sensitive fluorescent dye fura-2 was applied to measure [Ca(2+)]i. BAD induced [Ca(2+)]i rises in a concentration-dependent manner. The response was reduced by removing extracellular Ca(2+). BAD-evoked Ca(2+) entry was suppressed by nifedipine, econazole, and SK&F96365. In Ca(2+)-free medium, incubation with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin abolished BAD-induced [Ca(2+)]i rise. Inhibition of phospholipase C with U73122 did not alter BAD-induced [Ca(2+)]i rise. At 10-30µM, BAD inhibited cell viability, which was not reversed by chelating cytosolic Ca(2+). BAD (20-30µM) also induced apoptosis. Collectively, in OC2 cells, BAD induced a [Ca(2+)]i rise by evoking phospholipase C-independent Ca(2+) release from the endoplasmic reticulum and Ca(2+) entry via store-operated Ca(2+) channels. BAD also caused apoptosis.

Effect of sertraline on [Ca2+](i) and viability of human MG63 osteosarcoma cells.

The antidepressant, sertraline, has been shown to have diverse in vitro effects. This study examined whether sertraline altered [Ca(2+)](i) in MG63 human osteosarcoma cells by using fura-2 as a Ca(2+)-sensitive fluorescent dye. At 50-200 µM, sertraline induced a [Ca(2+)](i) rise in a concentration-dependent manner. Ca(2+) response was decreased by removing extracellular Ca(2+), suggesting that Ca(2+) entry and release contributed to the [Ca(2+)](i) signal. Sertraline-induced Ca(2+) entry was inhibited by nifedipine, La(3+), Gd(3+), and SK&F96365. When extracellular Ca(2+) was removed, pretreatment with the endoplasmic reticulum (ER) Ca(2+) pump inhibitor, thapsigargin, or 2,5-di-tert-butylhydroquinone (BHQ) abolished the sertraline-evoked [Ca(2+)](i) rise. Incubation with sertraline also abolished the thapsigargin or BHQ-induced [Ca(2+)](i) rise. Inhibition of phospholipase C (PLC) with U73122 abolished the sertraline-induced [Ca(2+)](i) rise. At 20-30 µM, overnight treatment with sertraline killed cells in a concentration-dependent manner. The cytotoxic effect of sertraline was not reversed by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Annexin V/propidium iodide staining data demonstrate that sertraline (30 µM) evoked apoptosis. Sertraline (20 and 30 µM) also increased levels of reactive oxygen species. Together, in human osteosarcoma cells, sertraline evoked a [Ca(2+)](i) rise by inducing PLC-dependent Ca(2+) release from the ER and Ca(2+) entry by L-type Ca(2+) channels and store-operated Ca(2+) channels. Sertraline induced cell death that may involve apoptosis by mitochondrial pathways.

Mechanism of [Ca2+]i rise induced by angiotensin 1-7 in MDCK renal tubular cells.

The effect of angiotensin 1-7 (Ang 1-7) on cytosolic Ca(2+) concentrations ([Ca(2+)](i)) in MDCK renal tubular cells was explored. The Ca(2+)-sensitive fluorescent dye fura-2 was applied to measure [Ca(2+)](i). Ang 1-7 at concentrations of 10-50 µM induced a [Ca(2+)](i) rise in a concentration-dependent manner. The response was reduced partly by removing Ca(2+). Ang 1-7 evoked store operated Ca(2+) entry that was inhibited by La(3+) and aristolochic acid. In the absence of extracellular Ca(2+), incubation with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin prevented Ang 1-7 from releasing more Ca(2+). Inhibition of phospholipase C with U73122 abolished Ang 1-7-induced [Ca(2+)](i) rise. Ang 1-7-induced [Ca(2+)](i) rise was abolished by the angiotensin type 1 receptor antagonist losartan, but was not affected by the angiotensin type 2 receptor antagonist PD 123,319. In sum, in MDCK cells, Ang 1-7 stimulated angiotensin type 1 receptors leading to a [Ca(2+)](i) rise that was composed of phospholipase C-dependent Ca(2+) release from the endoplasmic reticulum and Ca(2+) entry via phospholipase A2-sensitive store-operated Ca(2+) channels.

Effect of diindolylmethane on Ca2+ homeostasis and viability in PC3 human prostate cancer cells.

The effect of the natural product diindolylmethane on cytosolic Ca(2+) concentrations ([Ca(2+)](i)) and viability in PC3 human prostate cancer cells was explored. The Ca(2+)-sensitive fluorescent dye fura-2 was applied to measure [Ca(2+)](i). Diindolylmethane at concentrations of 20-50 µM induced [Ca(2+)](i) rise in a concentration-dependent manner. The response was reduced partly by removing Ca(2+). Diindolylmethane-evoked Ca(2+) entry was suppressed by nifedipine, econazole, SK&F96365, protein kinase C modulators and aristolochic acid. In the absence of extracellular Ca(2+), incubation with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ) inhibited or abolished diindolylmethane-induced [Ca(2+)](i) rise. Incubation with diindolylmethane also inhibited thapsigargin or BHQ-induced [Ca(2+)](i) rise. Inhibition of phospholipase C with U73122 reduced diindolylmethane-induced [Ca(2+)](i) rise. At concentrations of 50-100 µM, diindolylmethane killed cells in a concentration-dependent manner. This cytotoxic effect was not altered by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Annexin V/PI staining data implicate that diindolylmethane (50 and 100 µM) induced apoptosis in a concentration-dependent manner. In conclusion, diindolylmethane induced a [Ca(2+)](i) rise in PC3 cells by evoking phospholipase C-dependent Ca(2+) release from the endoplasmic reticulum and Ca(2+) entry via phospholipase A(2)-sensitive store-operated Ca(2+) channels. Diindolylmethane caused cell death in which apoptosis may participate.

Effect of methoxychlor on Ca(2+) movement and viability in MDCK renal tubular cells.

The effect of the insecticide methoxychlor on the physiology of renal tubular cells is unknown. This study aimed to explore the effect of methoxychlor on cytosolic Ca(2+) concentrations ([Ca(2+) ](i) ) in MDCK renal tubular cells using the Ca(2+) -sensitive fluorescent dye fura-2. Methoxychlor at 5-20 µM increased [Ca(2+) ](i) in a concentration-dependent manner. The signal was reduced by 80% by removing extracellular Ca(2+) . Methoxychlor-induced Ca(2+) entry was not affected by nifedipine and SK&F96365 but was inhibited by econazole and protein kinase C modulators. In Ca(2+) -free medium, treatment with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ) partly inhibited methoxychlor-induced [Ca(2+) ](i) rise. Incubation with methoxychlor also inhibited thapsigargin- or BHQ-induced [Ca(2+) ](i) rise. Inhibition of phospholipase C with U73122 nearly abolished methoxychlor-induced [Ca(2+) ](i) rise. At 5-15 µM, methoxychlor slightly increased cell viability, whereas at 20 µM, it decreased viability. The cytotoxic effect of methoxychlor was not reversed by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N,N-tetraacetic acid/AM (BAPTA/AM). Annexin V-FITC data suggest that 10 µM methoxychlor inhibited apoptosis, while 20 µM methoxychlor enhanced apoptosis. Methoxychlor (10 and 20 µM) increased the production of reactive oxygen species. Together, in renal tubular cells, methoxychlor induced [Ca(2+) ](i) rise by inducing phospholipase C-dependent Ca(2+) release from multiple stores and Ca(2+) entry via protein kinase C- and econazole-sensitive channels. Methoxychlor slightly enhanced or inhibited cell viability in a concentration-dependent, Ca(2+) -independent manner. Methoxychlor induced cell death that may involve apoptosis via mitochondrial pathways.

3,3'-Diindolylmethane alters Ca2+ homeostasis and viability in MG63 human osteosarcoma cells.

The effect of the natural product 3,3'-diindolylmethane (DIM) on cytosolic Ca(2+) concentrations ([Ca(2+)](i)) and viability in MG63 human osteosarcoma cells was explored. The Ca(2+)-sensitive fluorescent dye fura-2 was applied to measure [Ca(2+)](i). DIM at concentrations of 40-80 µM induced a [Ca(2+)](i) rise in a concentration-dependent manner. The response was reduced partly by removing Ca(2+). DIM-evoked Ca(2+) entry was suppressed by nifedipine, econazole, SK&F96365 and protein kinase C modulators. In the absence of extracellular Ca(2+), incubation with the endoplasmic reticulum Ca(2+) pump inhibitors thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ) inhibited or abolished DIM-induced [Ca(2+)](i) rise. Incubation with DIM also inhibited thapsigargin or BHQ-induced [Ca(2+)](i) rise. Inhibition of phospholipase C with U73122 abolished DIM-induced [Ca(2+)](i) rise. At concentrations of 10-50 µM, DIM killed cells in a concentration-dependent manner. This cytotoxic effect was not altered by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Annexin V/propidium iodide staining data implicate that DIM (20 and 40 µM) induced apoptosis in a concentration-dependent manner. In sum, in MG63 cells, DIM induced a [Ca(2+)](i) rise by evoking phospholipase C-dependent Ca(2+) release from the endoplasmic reticulum and Ca(2+) entry via protein kinase C-sensitive store-operated Ca(2+) channels. DIM caused cell death that may involve apoptosis.

Effect of celecoxib on Ca(2+) handling and viability in human prostate cancer cells (PC3).

Celecoxib has been shown to have an antitumor effect in previous studies, but the mechanisms are unclear. Ca(2+) is a key second messenger in most cells. The effect of celecoxib on cytosolic free Ca(2+) concentrations ([Ca(2+)](i)) in human suspended PC3 prostate cancer cells was explored by using fura-2 as a fluorescent dye. Celecoxib at concentrations between 5 and 30 µM increased [Ca(2+)](i) in a concentration-dependent manner. The Ca(2+) signal was reduced partly by removing extracellular Ca(2+). Celecoxib-induced Ca(2+) influx was not blocked by L-type Ca(2+) entry inhibitors or protein kinase C/A modulators [phorbol 12-myristate 13-acetate (PMA), GF109203X, H-89], but was inhibited by the phospholipase A(2) inhibitor, aristolochic acid. In Ca(2+)-free medium, 30 µM of celecoxib failed to induce a [Ca(2+)](i) rise after pretreatment with thapsigargin (an endoplasmic reticulum [ER] Ca(2+) pump inhibitor). Conversely, pretreatment with celecoxib inhibited thapsigargin-induced Ca(2+) release. Inhibition of phospholipase C with U73122 did not change celecoxib-induced [Ca(2+)](i) rises. Celecoxib induced slight cell death in a concentration-dependent manner, which was enhanced by chelating cytosolic Ca(2+) with BAPTA. Collectively, in PC3 cells, celecoxib induced [Ca(2+)](i) rises by causing phospholipase C-independent Ca(2+) release from the ER and Ca(2+) influx via non-L-type, phospholipase A(2)-regulated Ca(2+) channels. These data may contribute to the understanding of the effect of celecoxib on prostate cancer cells.

The mechanism of sertraline-induced [Ca(2+) ](i) rise in human PC3 prostate cancer cells.

The effect of sertraline, an antidepressant, on cytosolic-free Ca(2+) levels ([Ca(2+) ](i) ) in human cancer cells is unclear. This study examined whether sertraline altered basal [Ca(2+) ](i) levels in suspended PC3 human prostate cancer cells by using fura-2 as a Ca(2+) -sensitive fluorescent probe. At concentrations of 10-150 µM, sertraline induced a [Ca(2+) ](i) rise in a concentration-dependent fashion. The Ca(2+) signal was reduced partly by removing extracellular Ca(2+) indicating that Ca(2+) entry and release both contributed to the [Ca(2+) ](i) rise. Sertraline induced Mn(2+) influx, leading to quench of fura-2 fluorescence suggesting Ca(2+) influx. This Ca(2+) influx was inhibited by the suppression of store-operated Ca(2+) channels or by the modulation of protein kinase C activity. In Ca(2+) -free medium, pre-treatment with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin or 2,5-di-(t-butyl)-1,4-hydroquinone nearly abolished sertraline-induced Ca(2+) release. Conversely, pre-treatment with sertraline greatly reduced the inhibitor-induced [Ca(2+) ](i) rise, suggesting that sertraline released Ca(2+) from the endoplasmic reticulum. Inhibition of phospholipase C inhibited sertraline-induced [Ca(2+) ](i) rise. At 20-30 µM, sertraline killed cells in a concentration-dependent manner. The cytotoxic effect of sertraline was enhanced by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid/AM. Annexin V-FITC data suggest that sertraline (20 and 30 µM) evoked apoptosis in a concentration-dependent manner. Together, in PC3 human prostate cancer cells, sertraline induced [Ca(2+) ](i) rises by causing phospholipase C-dependent Ca(2+) release from the endoplasmic reticulum and via multiple Ca(2+) influx pathways that involve store-operated Ca(2+) channels. Sertraline also induced apoptosis that was not triggered by [Ca(2+) ](i) rise.

Effect of thapsigargin on Ca²+ fluxes and viability in human prostate cancer cells.

Effect of the carcinogen thapsigargin on human prostate cancer cells is unclear. This study examined if thapsigargin altered basal [Ca²âº](i) levels in suspended PC3 human prostate cancer cells by using fura-2 as a Ca²âº-sensitive fluorescent probe. Thapsigargin at concentrations between 10 nM and 10 µM increased [Ca²âº](i) in a concentration-dependent fashion. The Ca²âº signal was reduced partly by removing extracellular Ca²âº indicating that Ca²âº entry and release both contributed to the [Ca²âº](i) rise. This Ca²âº influx was inhibited by suppression of phospholipase A2, but not by inhibition of store-operated Ca²âº channels or by modulation of protein kinase C activity. In Ca²âº-free medium, pretreatment with the endoplasmic reticulum Ca²âº pump inhibitor 2,5-di-(t-butyl)-1,4-hydroquinone (BHQ) nearly abolished thapsigargin-induced Ca²âº release. Conversely, pretreatment with thapsigargin greatly reduced BHQ-induced [Ca²âº](i) rise, suggesting that thapsigargin released Ca²âº from the endoplasmic reticulum. Inhibition of phospholipase C did not change thapsigargin-induced [Ca²âº](i) rise. At concentrations of 1-10 µM, thapsigargin induced cell death that was partly reversed by chelation of Ca²âº with BAPTA/AM. Annexin V/propidium iodide staining data suggest that apoptosis was partly responsible for thapsigargin-induced cell death. Together, in PC3 human prostate cancer cells, thapsigargin induced [Ca²âº](i) rises by causing phospholipase C-independent Ca²âº release from the endoplasmic reticulum and Ca²âº influx via phospholipase A2-sensitive Ca²âº channels. Thapsigargin also induced cell death via Ca²âº-dependent pathways and Ca²âº-independent apoptotic pathways.