maxacalcitol and Leukemia--Myeloid

We originally reported that vitamin K(2) (VK2) effectively induces apoptosis in various types of primary cultured leukemia cells and leukemia cell lines in vitro. In addition, VK2 was shown to induce differentiation of leukemia cells when the cells were resistant against VK2-inducing apoptosis. A novel synthetic vitamin D(3)derivative, 22-oxa-1,25-dihydroxyvitamin D(3) (OCT: oxacarcitriol) shows a more potent differentiation-inducing ability among myeloid leukemia cells in vitro with much lesser extent of the induction of hypercalcemia in vivo as compared to the effects of 1alpha,25(OH)(2)D(3). In the present study, we focused on the effects of a combination of OCT plus VK2 on leukemia cells. Treatment of HL-60 cells with OCT for 72 h induces monocytic differentiation. A combination of OCT plus VK2 dramatically enhances monocytic differentiation as assessed by morphologic features, positivity for non-specific esterase staining, and cell surface antigen expressions. This combined effect far exceeds the maximum differentiation induction ability at the optimal concentrations of either OCT or VK2 alone. In addition, pronounced accumulation of the cells in the G0/G1 phase is observed by combined treatment with OCT plus VK2 as compared with each vitamin alone. In contrast to cell differentiation, caspase-3 activation and apoptosis induction in response to VK2 are significantly suppressed in the presence of OCT in HL-60 cells. These data suggest that monocytic differentiation and apoptosis induction of HL-60 cells are inversely regulated. Furthermore, pronounced induction of differentiation by combined treatment with VK2 plus OCT was also observed in four out of six cases of primary cultured acute myeloid leukemia cells in vitro, suggesting that VK2 plus OCT might be a potent combination for the differentiation-based therapy for acute myeloid leukemias.

Topics: Acute Disease; Antineoplastic Agents; Apoptosis; Calcitriol; Cell Differentiation; Drug Screening Assays, Antitumor; Drug Synergism; Female; Gene Expression Regulation, Leukemic; HL-60 Cells; Humans; Leukemia, Myeloid; Male; Middle Aged; Neoplasms, Second Primary; Neoplastic Stem Cells; Tumor Cells, Cultured; Vitamin K 2

The agent 1,25-dihydroxyvitamin D3 (D3) induces the differentiation of HL-60 human leukemia cells into functional monocyte-like cells that can support the intracellular multiplication of Legionella pneumophila. 22-Oxacalcitriol (OCT), a synthetic analogue of D3, exhibits greater differentiation-inducing activity than D3 in WEHI-3 mouse leukemia cells and has been suggested to be clinically more useful because of its lower hypercalcemic activity. The abilities of OCT and D3 to induce the functional differentiation of human leukemia HL-60 cells have now been investigated. OCT induced the differentiation of HL-60 cells into monocyte-like cells to a similar extent as D3. Thus, both OCT and D3 increased (1) the surface expression of CD11b, CD11c, CD14, and CD35; (2) nonspecific esterase staining; and (3) phagocytic activity toward fluorescent beads. HL-60 cells differentiated in response to OCT also supported the intracellular multiplication of L. pneumophila. Activation of both OCT- and D3-treated HL-60 cells with human recombinant interferon-gamma (IFN-gamma) for 24 h before infection markedly inhibited L. pneumophila multiplication. IFN-gamma activation enhanced superoxide anion generation by D3-treated HL-60 cells but not by OCT-treated HL-60 cells, suggesting that the inhibition of L. pneumophila multiplication in IFN-gamma-activated cells is independent of superoxide generation. Finally, D3, but not OCT, markedly stimulated the formation of osteoclast-like multinucleated cells from mouse bone marrow cells, consistent with the lower hypercalcemic activity of OCT.

Topics: Animals; Antineoplastic Agents; Bone Marrow; Bone Marrow Cells; Calcitriol; Cell Differentiation; Humans; Interferon-gamma; Intracellular Fluid; Legionella pneumophila; Leukemia, Myeloid; Mice; Monocytes; Osteoclasts; Recombinant Proteins; Superoxides; Tumor Cells, Cultured

Four vitamin D3 analogues, 1 alpha,24(S)- and 1 alpha,24(R)-dihydroxy-22-oxavitamin D3 (5 and 6) and their 20(R)-epimers (7 and 8) were synthesized from the 20(S)-alcohol (10). In tests of activity to induce differentiation of human myeloid leukemia cells (HL-60) to macrophages, 5 showed comparable activity to 1 alpha,25-dihydroxy-22-oxavitamin D3 (OCT) (2), and the other three analogues (6, 7 and 8) were less active than OCT (2). The binding properties of these analogues to the chick embryonic intestinal 1 alpha,25-dihydroxyvitamin D3 (1) receptor were evaluated. Furthermore, 20(R)-OCT (9) was synthesized and its biological properties were compared with those of OCT(2) and the 20(R)-epimers (7 and 8).

Topics: Animals; Antineoplastic Agents; Calcitriol; Cell Differentiation; Chick Embryo; Cholecalciferol; Humans; Isomerism; Leukemia, Myeloid; Macrophages; Receptors, Calcitriol; Tumor Cells, Cultured