Effect of miconazole on intracellular Ca 2+ levels and proliferation in human osteosarcoma cells

Abstract

The effect of miconazole, an anti-fungal drug, on cytoplasmic free Ca 2+ concentrations ([Ca 2+] i) in human osteosarcoma cells (MG63) was explored by using the Ca 2+-sensitive dye fura-2. Miconazole acted in a concentration-dependent manner with an EC 50 of 75 μM. The Ca 2+ signal comprised a gradual rise and a sustained elevation. Removal of extracellular Ca 2+ reduced 50% of the signal. In Ca 2+-free medium, the [Ca 2+] i rise induced by 1 μM thapsigargin (an endoplasmic reticulum Ca 2+ pump inhibitor) was completely inhibited by pretreatment with 20 μM miconazole. Pretreatment with thapsigargin partly inhibited miconazole-induced Ca 2+ release. The miconazole-induced Ca 2+ release was not changed by inhibition of phospholipase C with 2 μM U73122. By using tetrazolium as a fluorescent probe, it was shown that 10–100 μM miconazole decreased cell proliferation rate in a concentration-dependent manner. Collectively, this study shows that miconazole induces [Ca 2+] i rises in human osteosarcoma cells via releasing Ca 2+ mainly from the endoplasmic reticulum in a manner independent of phospholipase C activity, and by causing Ca 2+ influx. Furthermore, miconazole may be cytotoxic to the cells at higher concentrations.