Biological activity of fluorinated vitamin D analogs at C-26 and C-27 on human promyelocytic leukemia cells, HL-60.
Vitamin D compounds added to the culture medium induce HL-60 cells to differentiate into macrophage/monocytes via a receptor mechanism. This system provides a biologically relevant assay for the study of biopotency of vitamin D analogs. Using this system, the biological activity of various fluorinated derivatives of vitamin D3 was compared with that of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3). As assessed by cell morphology, nitroblue tetrazolium reduction and nonspecific esterase activity, 26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D3 (26,27-F6-1,25-(OH)2D3) and 26,26,26,27,27,27-hexafluoro-1,24-dihydroxyvitamin D3 (26,27-F6-1,24-(OH)2D3) were about 10 times as potent as 1,25-(OH)2D3 in suppressing HL-60 cell proliferation and inducing cell differentiation. The biological activity of 26,26,26,27,27,27-hexafluoro-1-hydroxyvitamin D3 (26,27-F6-1-OH-D3) was equal to that of 1,25-(OH)2D3 in this system. 1,25-(OH)2D3 and its fluorinated analogs exerted their effects on HL-60 cells in a dose-dependent manner. HL-60 cells have a specific receptor for 1,25-(OH)2D3 with an apparent Kd of 0.25 nM, identical with that of chick intestinal receptor. While the binding affinities of 26,27-F6-1,25-(OH)2D3 and 26,27-F6-1,24-(OH)2D3 for chick intestinal receptor were lower than that of 1,25-(OH)2D3 by factors of 3 and 1.5, respectively, they were as competent as 1,25-(OH)2D3 in binding to HL-60 cell receptor. The ability of 26,27-F6-1-OH-D3 to compete for receptor protein from HL-60 cells and chick intestine was about 1/70 that of 1,25-(OH)2D3. These results indicate that trifluorination of carbons 26 and 27 of vitamin D3 can markedly enhance the effect on HL-60 cells.
Inaba
M
M
Second Department of Internal Medicine, Osaka City University Medical School, Japan.
Okuno
S
S
Nishizawa
Y
Y
Yukioka
K
K
Otani
S
S
Matsui-Yuasa
I
I
Morisawa
S
S
DeLuca
H F
HF
Morii
H
H
D000818:Animals; D001667:Binding, Competitive; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D002645:Chickens; D005461:Fluorine; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007700:Kinetics; D015470:Leukemia, Myeloid, Acute; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000378:metabolism*
D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D005461:Fluorine; D002117:Calcitriol