1,25-Dihydroxyvitamin D3 (1,25[OH]2D3) caused a rise in the concentration of intracellular free calcium ions ([Ca2+](i)) in HL-60 cells. This effect of 1,25(OH)2D3 parallels its suppression of cell proliferation and its induction of cell differentiation into monocyte-like cells. The changes in [Ca2+](i) are dose and time time dependent. The concentration of 1,25(OH)2D3 (10-7 M) that induced maximal differentiation also caused the maximal increase in intracellular Ca2+. The rise in cytoplasmic free Ca2+ concentration was not immediate and reached statistical significance only after 24 h. The [Ca2+](i) reached its peak at 48 h (134 ± 4 nM vs 101 ± 3 nM in controls) and remained stable at this level. The increase in intracellular Ca2+ was found to be related to new protein synthesis, because it was inhibited in the presence of specific RNA and protein synthesis inhibitors. The rise in [Ca2+](i) was not observed during incubation of HL-60 cells with 24,25-dihydroxyvitamin D3 (24,25[OH]2D3), a vitamin D metabolite that does not induce the differentiation of HL-60 cells. In contrast, 25-hydroxyvitamin D3 (25-OH-D3) and phorbol 12-myristate 13-acetate (TPA), both of which induce differentiation in this cell line, also increase [Ca2+](i). In conclusion, the present study emphasizes that a significant increase in intracellular free Ca2+ occurs in the effect of 1,25(OH)2D3 on HL-60 cells.
|Number of pages||5|
|State||Published - 1 Dec 1990|
- Cytosolic free calcium
- HL-60 cells