Carvacrol, a monoterpenic phenol compound, has been shown to possess various biological effects in different models. However, the effect of carvacrol on intracellular Ca²⁺ and its related physiology in human prostate cancer is unknown. This study explored the effect of carvacrol on cytosolic free Ca²⁺ levels ([Ca²⁺]i) and viability in PC3 human prostate cancer cells. Fura-2, a Ca²⁺- sensitive fluorescent dye, was used to assess [Ca²⁺]i. Cell viability was measured by the detecting reagent WST-1. Carvacrol at concentrations of 200-800 μM caused [Ca²⁺]i rises in a concentration-dependent manner. Removal of extracellular Ca²⁺ reduced carvacrol’s effect by approximately 60%. Carvacrol-induced Ca²⁺ entry was confirmed by Mn²⁺ entry-induced quench of fura-2 fluorescence, and was inhibited by approximately 30% by nifedipine, econazole, SKF96365, and the protein kinase C (PKC) inhibitor GF109203X. In Ca²⁺-free medium, treatment with the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin (TG) abolished carvacrol-induced [Ca²⁺]i rises. Treatment with carvacrol also abolished TG-induced [Ca²⁺]i rises. Carvacrol-induced Ca²⁺ release from the endoplasmic reticulum was abolished by inhibition of phospholipase C (PLC). Carvacrol killed cells at concentrations of 200-600 μM in a concentration-dependent fashion. Chelating cytosolic Ca²⁺ with BAPTA/AM did not prevent carvacrol’s cytotoxicity. Together, in PC3 cells, carvacrol induced [Ca²⁺]i rises by inducing PLC-dependent Ca²⁺ release from the endoplasmic reticulum and Ca²⁺ entry via PKC-sensitive store-operated Ca²⁺ channels and other unknown channels. Carvacrol also induced Ca²⁺-dissociated cell death.

Protriptyline, a tricyclic anti-depressant, is used primarily to treat the combination of symptoms of anxiety and depression. However, the effect of protriptyline on prostate caner is unknown. This study examined whether the anti-depressant protriptyline altered Ca(2+) movement and cell viability in PC3 human prostate cancer cells. The Ca(2+)-sensitive fluorescent dye fura-2 was used to measure [Ca(2+)](i). Protriptyline evoked [Ca(2+)](i) rises concentration-dependently. The response was reduced by removing extracellular Ca(2+). Protriptyline-evoked Ca(2+) entry was inhibited by store-operated channel inhibitors (nifedipine, econazole and SKF96365), protein kinase C activator (phorbol 12-myristate 13 acetate, PMA) and protein kinase C inhibitor (GF109203X). Treatment with the endoplasmic reticulum Ca(2+) pump inhibitor 2,5-di-tert-butylhydr-oquinone (BHQ) in Ca(2+)-free medium inhibited 60% of protriptyline-evoked [Ca(2+)](i) rises. Conversely, treatment with protriptyline abolished BHQ-evoked [Ca(2+)](i) rises. Inhibition of phospholipase C with U73122 suppressed 50% of protriptyline-evoked [Ca(2+)](i) rises. At concentrations of 50-70 µM, protriptyline decreased cell viability in a concentration-dependent manner; which were not reversed by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA/AM). Collectively, in PC3 cells, protriptyline evoked [Ca(2+)](i) rises by inducing phospholipase C-associated Ca(2+) release from the endoplasmic reticulum and other stores, and Ca(2+) influx via protein kinase C-sensitive store-operated Ca(2+) channels. Protriptyline caused cell death that was independent of [Ca(2+)](i) rises.

The effect of sertraline, a selective serotonin reuptake inhibitor (SSRI), on cytosolic free Ca²⁺ concentrations ([Ca²⁺](i)) in a rabbit corneal epithelial cell line (SIRC) is unclear. This study explored whether sertraline changed basal [Ca²⁺](i) levels in suspended SIRC cells by using fura-2 as a Ca²⁺-sensitive fluorescent dye. Sertraline at concentrations between 10-100 μM increased [Ca²⁺](i) in a concentration-dependent manner. The Ca²⁺ signal was reduced by 23% by removing extracellular Ca²⁺. Sertraline induced Mn²⁺ influx, leading to quench of fura-2 fluorescence, suggesting Ca²⁺ influx. This Ca²⁺ influx was inhibited by phospholipase A₂ inhibitor aristolochic acid, but not by store-operated Ca²⁺ channel blockers and protein kinase C/A modulators. In Ca²⁺-free medium, pretreatment with the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin, cyclopiazonic acid or 2,5-di-tert-butylhydroquinone greatly inhibited sertraline-induced Ca²⁺ release. Inhibition of phospholipase C with U73122 abolished sertraline-induced [Ca²⁺](i) rise. At concentrations of 5-50 μM, sertraline killed cells in a concentration-dependent manner. The cytotoxic effect of 25 μM sertraline was not reversed by prechelating cytosolic Ca²⁺ with BAPTA/AM. Collectively, in SIRC cells, sertraline induced [Ca²⁺](i) rises by causing phospholipase C-dependent Ca²⁺ release from the endoplasmic reticulum and Ca²⁺ influx via phospholipase A₂-sensitive Ca²⁺ channels. Sertraline-caused cytotoxicity was mediated by Ca²⁺-independent pathways.

No abstract

Safrole is a carcinogen found in plants. The effect of safrole on cytosolic free Ca²⁺ concentrations ([Ca²⁺](i)) and viability in SCM1 human gastric cancer cells was explored. The Ca²⁺-sensitive fluorescent dye fura-2 was applied to measure [Ca²⁺](i). Safrole at concentrations of 150-450 μM induced a [Ca²⁺](i) rise in a concentration-dependent manner. The response was reduced by 60% by removing extracellular Ca²⁺. Safrole-evoked Ca²⁺ entry was not altered by nifedipine, econazole, SKF96365, and protein kinase C activator or inhibitor. In Ca²⁺-free medium, treatment with the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ) abolished safrole-evoked [Ca²⁺](i) rises. Conversely, treatment with safrole abolished thapsigargin or BHQ-evoked [Ca²⁺](i) rises. Inhibition of phospholipase C (PLC) with U73122 abolished safrole-induced [Ca²⁺](i) rises. At 250-550 μM, safrole decreased cell viability concentration-dependently, which was not reversed by chelating cytosolic Ca²⁺ with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid/acetoxy methyl (BAPTA/AM). Annexin V/propidium iodide staining data suggest that safrole (350-550 μM) induced apoptosis concentration-dependently. These studies suggest that in SCM1 human gastric cancer cells, safrole induced [Ca²⁺](i) rises by inducing PLC-dependent Ca²⁺ release from the endoplasmic reticulum and Ca²⁺ influx via non-store-operated Ca²⁺ entry pathways. Safrole-induced cell death may involve apoptosis.