Exploration of Niflumic Acid ’s Action on Ca²⁺ Movement and Cell Viability in Human Osteosarcoma Cells.
This study examined the effect of niflumic acid on
cytosolic free Ca²⁺ concentrations ([Ca²⁺]i) in MG63 human osteosarcoma cells. Intracellular Ca²⁺
concentrations in suspended cells were monitored by using the fluorescent Ca²⁺-sensitive dye fura-
2. Cell viability was examined by using 4-[3-[4-lodophenyl]-2-4(4-nitrophenyl)-2H-5-tetrazolio-
1,3-benzene disulfonate] water soluble tetrazolium-1 (WST-1). In MG63 cells, niflumic acid at
concentrations of 250-750 μM evoked [Ca²⁺]i rises concentration-dependently. Niflumic acid-evoked
Ca²⁺ entry was confirmed by Mn²⁺-induced quenching of fura-2 fluorescence. This entry
was inhibited by nifedipine, econazole, SKF96365, the protein kinase C (PKC) activator phorbol
12-myristate 13 acetate (PMA), but was not affected by the PKC inhibitor GF109203X. In Ca²⁺-
free medium, treatment with the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin (TG)
inhibited niflumic acid-evoked [Ca²⁺]i rises. Conversely, treatment with niflumic acid abolished TG-evoked
[Ca²⁺]i rises. Inhibition of phospholipase C (PLC) with U73122 also partly reduced niflumic
acid-evoked [Ca²⁺]i rises. Niflumic acid killed cells at 200-500 μM in a concentration-dependent
fashion. Chelating cytosolic Ca²⁺ with 1,2-bis(2-aminophenoxy)ethane-N,N,N’,N’-tetraacetic acid/
AM (BAPTA/AM) did not reverse niflumic acid-induced cytotoxicity. Collectively, our data suggest
that in MG63 cells, niflumic acid induced [Ca²⁺]i rises by e...
Source: The Chinese Journal of Physiology - Category: Physiology Tags: Chin J Physiol Source Type: research