cholecalciferol and Leukemia--Myelomonocytic--Acute

1alpha,25-dihydroxyvitamin D(3) (1,25D(3)) is a powerful differentiation agent, which has potential for treatment of myeloid leukemias and other types of cancer, but the calcemia produced by pharmacologically active doses precludes the use of this agent in the clinic. We have shown that carnosic acid, the major rosemary polyphenol, enhances the differentiating and antiproliferative effects of low concentrations of 1,25D(3) in human myeloid leukemia cell lines (HL60, U937). Here we translated these findings to in vivo conditions using a syngeneic mouse leukemia tumor model. To this end, we first demonstrated that as in HL60 cells, differentiation of WEHI-3B D(-) murine myelomonocytic leukemia cells induced by 1 nM 1,25D(3) or its low-calcemic analog, 1,25-dihydroxy-16-ene-5,6-trans-cholecalciferol (Ro25-4020), can be synergistically potentiated by carnosic acid (10 microM) or the carnosic acid-rich ethanolic extract of rosemary leaves. This effect was accompanied by cell cycle arrest in G0 + G1 phase and a marked inhibition of cell growth. In the in vivo studies, i.p. injections of 2 microg Ro25-4020 in Balb/c mice bearing WEHI-3B D(-) tumors produced a significant delay in tumor appearance and reduction in tumor size, without significant toxicity. Another analog, 1,25-dihydroxy-16,23Z-diene-20-epi-26,27-hexafluoro-19-nor-cholecalciferol (Ro26-3884) administered at the same dose was less effective than Ro25-4020 and profoundly toxic. Importantly, combined treatment with 1% dry rosemary extract (mixed with food) and 1 microg Ro25-4020 resulted in a strong cooperative antitumor effect, without inducing hypercalcemia. These results indicate for the first time that a plant polyphenolic preparation and a vitamin D derivative can cooperate not only in inducing leukemia cell differentiation in vitro, but also in the antileukemic activity in vivo. These data may suggest novel protocols for chemoprevention or differentiation therapy of myeloid leukemia.

Topics: Abietanes; Animals; Anticarcinogenic Agents; Antineoplastic Agents; Apoptosis; Calcium; Cholecalciferol; Dose-Response Relationship, Drug; Drug Synergism; Flavonoids; Leukemia, Experimental; Leukemia, Myeloid; Leukemia, Myelomonocytic, Acute; Mice; Mice, Inbred BALB C; Phenols; Plant Extracts; Plant Preparations; Polyphenols; Rosmarinus; Tumor Cells, Cultured

The CD14 antigen was originally described as a differentiation antigen on mononuclear cells. The purpose of this study was to investigate the relationship between the appearance of surface CD14 and the acquisition of lipopolysaccharide (LPS) responsiveness during maturation of mononuclear phagocytes. Immature THP-1 cells responded poorly to LPS in the absence or presence of serum. Treatment with the maturational agent calcitriol caused a dose- and time-dependent increase in CD14 mRNA and surface CD14 and enhanced the responsiveness of THP-1 cells to smooth and rough form LPS, complexes of LPS and lipopolysaccharide-binding protein (LBP), and LPS in low concentrations of serum. Monoclonal antibodies to CD14 blocked the responses of THP-1 to LPS, LPS-LBP complexes and LPS in serum. Immunodepletion of LBP from serum also inhibited the effect of LPS in serum. The data show that maturation of the response of THP-1 cells to LPS and LPS-LBP complexes depends on the appearance of CD14 on the cell surface. Maturation of the response to LPS in serum depends in large part on the appearance of CD14 on the cell surface and the presence of LBP in serum.

Topics: Actins; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Base Sequence; Blood Proteins; CD18 Antigens; Cell Differentiation; Cholecalciferol; Culture Media; DNA; Dose-Response Relationship, Drug; Endotoxins; Flow Cytometry; Humans; Leukemia, Myelomonocytic, Acute; Lipopolysaccharide Receptors; Lipopolysaccharides; Molecular Sequence Data; Phagocytes; RNA, Messenger; Time Factors; Tumor Cells, Cultured