Effect of Thymol on Ca²⁺ Homeostasis and Viability in MG63 Human Osteosarcoma Cells

Abstract

Aims: The effect of the natural product thymol on cytosolic Ca²⁺ concentrations ([Ca²⁺]_i) and viability in MG63 human osteosarcoma cells was examined. Methods: The Ca²⁺-sensitive fluorescent dye fura-2 was applied to measure [Ca²⁺]_i. Results: Thymol at concentrations of 200–1,000 µmol/l induced a [Ca²⁺]_i rise in a concentration-dependent fashion. The response was decreased partially by removal of extracellular Ca²⁺. Thymol-induced Ca²⁺ entry was inhibited by nifedipine, econazole, SK&F96365 and protein kinase C modulators. When extracellular Ca²⁺ was removed, incubation with the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ) inhibited the thymol-induced [Ca²⁺]_i rise. Incubation with thymol also inhibited the thapsigargin or BHQ-induced [Ca²⁺]_i rise. Inhibition of phospholipase C with U73122 abolished the thymol-induced [Ca²⁺]_i rise. At concentrations of 100–600 µmol/l, thymol killed cells in a concentration-dependent manner. This cytotoxic effect was not changed by chelating cytosolic Ca²⁺ with 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid/AM. Annexin V/propidium iodide staining data suggest that thymol (200 and 400 µmol/l) induced apoptosis in a concentration-dependent manner. Thymol (200 and 400 µmol/l) also increased levels of reactive oxygen species. Conclusions: In MG63 cells, thymol induced a [Ca²⁺]_i rise by inducing phospholipase C-dependent Ca²⁺ release from the endoplasmic reticulum and Ca²⁺ entry via protein kinase C-sensitive store-operated Ca²⁺ channels. Thymol induced cell death that may involve apoptosis via mitochondrial pathways.

IgE-mediated mast cell responses are inhibited by thymol-mediated, activation-induced cell death in skin inflammation

“…Mast cell degranulation and histamine production is Ca 2+ dependent and thymol has previously been shown to mobilize calcium stores in glioblastoma, 29 osteoblastoma, 31 and pituitary GH3 cells. 30 To test whether thymol directly affects mast cell Ca 2+ flux, BMMCs were load with fluo-4-AM and analyzed by flow cytometry before and after thymol stimulation.…”

“…28 Despite this very early clinical report, the use of thymol in treating skin inflammation has not been further pursued, perhaps because the underlying mechanisms are unknown. Studies investigating the effect of thymol in vitro have shown that low thymol concentrations of can promote calcium mobilization 29-31 and protect cells from DNA damage, 32, 33 radiation-induced cytotoxicity, 25 and oxidative stress. 34 Conversely, at higher concentrations, it inhibits cell proliferation and can induce apoptosis in human and murine cancer cell lines.…”

Regulation of C6 glioma cell migration by thymol

“…The anticancer effect of thymol on various cancers has been reported (20)(21)(22)(23)(24). However, the effect of thymol on the motility of glioma cells…”

Efficacy of Essential Oils ofThymus vulgarisandOriganum vulgareonEchinococcus granulosus

“…Permeabilization of outer and inner mitochondrial membranes leads to cell death by apoptosis and necrosis [71, 72]. Apoptosis induced by thymol in cancer cells was associated with mitochondrial pathway [73, 74]. TUNEL assay revealed that thymol and essential oils of T. vulgaris and O. vulgare can induce apoptosis in the cells of protoscoleces.…”