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The effect of the natural product 3,3′-diindolylmethane (DIM) on cytosolic Ca2+ concentrations ([Ca2+]i) and viability in MG63 human osteosarcoma cells was explored. The Ca2+-sensitive fluorescent dye fura-2 was applied to measure [Ca2+]i. DIM at concentrations of 40-80 μM induced a [Ca2+]i rise in a concentration-dependent manner. The response was reduced partly by removing Ca2+. DIM-evoked Ca2+ entry was suppressed by nifedipine, econazole, SK&F96365 and protein kinase C modulators. In the absence of extracellular Ca2+, incubation with the endoplasmic reticulum Ca2+ pump inhibitors thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ) inhibited or abolished DIM-induced [Ca2+]i rise. Incubation with DIM also inhibited thapsigargin or BHQ-induced [Ca2+]i rise. Inhibition of phospholipase C with U73122 abolished DIM-induced [Ca2+]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 Ca2+ 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 [Ca2+]i rise by evoking phospholipase C-dependent Ca2+ release from the endoplasmic reticulum and Ca2+ entry via protein kinase C-sensitive store-operated Ca2+ channels. DIM caused cell death that may involve apoptosis. [ABSTRACT FROM AUTHOR]

The effect of sertraline, an antidepressant, on cytosolic-free Ca2+ levels ([Ca2+]i) in human cancer cells is unclear. This study examined whether sertraline altered basal [Ca2+]i levels in suspended PC3 human prostate cancer cells by using fura-2 as a Ca2+-sensitive fluorescent probe. At concentrations of 10-150 lM, sertraline induced a [Ca2+]i rise in a concentration- dependent fashion. The Ca2+signal was reduced partly by removing extracellular Ca2+indicating that Ca2+entry and release both contributed to the [Ca2+]i rise. Sertraline induced Mn2+ influx, leading to quench of fura-2 fluorescence suggesting Ca2+ influx. This Ca2+ influx was inhibited by the suppression of store-operated Ca2+ channels or by the modulation of protein kinase C activity. In Ca2+-free medium, pre-treatment with the endoplasmic reticulum Ca2+ pump inhibitor thapsigargin or 2,5-di-(t-butyl)-1,4-hydroquinone nearly abolished sertraline-induced Ca2+release. Conversely, pre-treatment with sertraline greatly reduced the inhibitor-induced [Ca2+]i rise, suggesting that sertraline released Ca2+from the endoplasmic reticulum. Inhibition of phospholipase C inhibited sertraline-induced [Ca2+]i rise. At 20-30 μM, sertraline killed cells in a concentrationdependent manner. The cytotoxic effect of sertraline was enhanced by chelating cytosolic Ca2+ 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 [Ca2+]i rises by causing phospholipase C-dependent Ca2+ release from the endoplasmic reticulum and via multiple Ca2+ influx pathways that involve store-operated Ca2+ channels. Sertraline also induced apoptosis that was not triggered by [Ca2+]i rise. [ABSTRACT FROM AUTHOR]

1. It has been shown that the antidepressant desipramine is able to induce increases in [Ca2+]i and cell death in MG63 human osteosacroma cells, but whether apoptosis is involved is unclear. In the present study, the effect of desipramine on apoptosis and the underlying mechanisms were explored. It was demonstrated that desipramine induced cell death in a concentration- and time-dependent manner. 2. Cells treated with 100–800 mmol/L desipramine showed typical apoptotic features, including an increase in sub-diploid nuclei and activation of caspase 3, indicating that these cells underwent apoptosis. Immunoblotting revealed that 100 mmol/L desipramine activated extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). Although pretreatment of cells with 20 mmol/L PD98059 (an ERK inhibitor) or 20 mmol/L SP600125 (an inhibitor of JNK) did not inhibit cell death, the addition of 20 mmol/L SB203580 (a p38 MAPK inhibitor) partially rescued cells from apoptosis. Desipramine-induced caspase 3 activation required p38 MAPK activation. 3. Pretreatment of cells with BAPTA/AM (20 mmol/L) to prevent desipramine-induced increases in [Ca2+]i did not protect cells from death. 4. The results of the present study suggest that, in MG63 human osteosarcoma cells, desipramine causes Ca2+-independent apoptosis by inducing p38 MAPK-associated activation of caspase 3. [ABSTRACT FROM AUTHOR]

Limited information is available concerning the effects of aerobic exercise on vasorelaxation in hypertension. The aim of this study was to investigate the effects of a single bout of aerobic exercise on insulin- and insulin-like growth factor-1 (IGF-1)-induced vasorelaxation in hypertensive rats. Four-month-old spontaneously hypertensive rats were randomly divided into a sedentary group (SHR) and an exercise group (SHR+Ex) subjected to a single bout of aerobic exercise conducted by treadmill running at 21 m min(1) for 1 h. Age-matched Wistar-Kyoto rats were used as a normotensive control group (WKY). Insulin- and IGF-1-induced vasorelaxant responses in the three groups were evaluated by using isolated aortic rings, with or without endothelial denudation, in organ baths. Possible roles of phosphatidylinositol 3-kinase (PI3K) and nitric oxide synthase (NOS) involved in the NO-dependent vasorelaxation were examined by adding selective inhibitors. The role of superoxide was also clarified by adding superoxide dismutase (SOD). In addition, the endothelium-independent vascular responses to sodium nitroprusside (SNP), a NO donor, were examined. The insulin- and IGF-1-induced vasorelaxation was significantly (P < 0.05) decreased in the SHR group compared with the WKY group. This decreased response in SHR was improved by exercise. These vasorelaxant responses among the three groups became similar after endothelial denudation and pretreatment with the PI3K inhibitor, NOS inhibitor or SOD. Also, no difference among groups was found in the SNP-induced vasorelaxation. We concluded that a single bout of aerobic exercise acutely improves insulin- and IGF-1-mediated vasorelaxation in an endothelium-dependent manner in hypertensive rats.

1. It has been shown that the antidepressant desipramine is able to induce increases in [Ca(2+)](i) and cell death in MG63 human osteosacroma cells, but whether apoptosis is involved is unclear. In the present study, the effect of desipramine on apoptosis and the underlying mechanisms were explored. It was demonstrated that desipramine induced cell death in a concentration- and time-dependent manner. 2. Cells treated with 100-800 mmol/L desipramine showed typical apoptotic features, including an increase in sub-diploid nuclei and activation of caspase 3, indicating that these cells underwent apoptosis. Immunoblotting revealed that 100 mmol/L desipramine activated extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). Although pretreatment of cells with 20 mmol/L PD98059 (an ERK inhibitor) or 20 mmol/L SP600125 (an inhibitor of JNK) did not inhibit cell death, the addition of 20 mmol/L SB203580 (a p38 MAPK inhibitor) partially rescued cells from apoptosis. Desipramine-induced caspase 3 activation required p38 MAPK activation. 3. Pretreatment of cells with BAPTA/AM (20 mmol/L) to prevent desipramine-induced increases in [Ca(2+)](i) did not protect cells from death. 4. The results of the present study suggest that, in MG63 human osteosarcoma cells, desipramine causes Ca(2+)-independent apoptosis by inducing p38 MAPK-associated activation of caspase 3.