1,25-Dihydroxyvitamin D3 enhances cytosolic free calcium in HL-60 cells.
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 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.
Barnea
E
E
Clinical Biochemistry Unit, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva, Israel.
Levy
R
R
Zimlichman
R
R
Shany
S
S
D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D003600:Cytosol / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007700:Kinetics; D015473:Leukemia, Promyelocytic, Acute; D013050:Spectrometry, Fluorescence; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014807:Vitamin D / Q000494:pharmacology
D014807:Vitamin D; D002117:Calcitriol; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium