37 research outputs found
Establishment and characterization of a human mixed-lineage, T- lymphoid/myeloid cell line (USP-91)
Establishment and characterization of a human mixed-lineage, T- lymphoid/myeloid cell line (USP-91)
Distribution and Functional Properties of PNA+ and PNA- Cells in Central and Peripheral Lymphoid Organs of the Chicken
Synergistic decrease of clonal proliferation, induction of differentiation, and apoptosis of acute promyelocytic leukemia cells after combined treatment with novel 20-epi vitamin D3 analogs and 9-cis retinoic acid.
Patients with acute promyelocytic leukemia (APL) usually relapse after all-trans retinoic acid (RA) treatment because this therapy fails to eradicate the malignant clone. Our data showed that KH 1060 and other 20-epi vitamin D3 analogs alone were potent inhibitors of clonal growth of NB4 cells, an APL cell line (ED50, approximately 5 x 10(-11) M). The combination of KH 1060 and 9-cis-RA synergistically and irreversibly enhanced this effect. Neither KH 1060 nor 9-cis-RA (10(-6) M, 3 d) were strong inducers of differentiation of NB4 cells. However, 98% of the cells underwent differentiation to a mature phenotype with features of both granulocytes and monocytes after exposure to a combination of both compounds. Apoptosis only increased after incubation of NB4 cells with 9-cis-RA alone (28%) or with a combination of 9-cis-RA plus KH1060 (32%). Immunohistochemistry showed that the bcl-2 protein decreased from nearly 100% of the wild-type NB4 cells to 2% after incubation with a combination of KH 1060 and 9-cis-RA, and the bax protein increased from 50% of wild-type NB4 cells to 92% after culture with both analogs (5 x 10(-7) M, 3 d). Western blot analysis paralleled these results. Studies of APL cells from one untreated individual paralleled our results with NB4 cells. Taken together, the data demonstrated that nearly all of the NB4 cells can be irreversibly induced to differentiate terminally when exposed to the combination of KH 1060 and 9-cis-RA
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Combination of a potent 20-epi-vitamin D3 analogue (KH 1060) with 9-cis-retinoic acid irreversibly inhibits clonal growth, decreases bcl-2 expression, and induces apoptosis in HL-60 leukemic cells.
All-trans retinoic acid (RA) is the first highly effective differentiation-inducing agent for remission induction in patients with acute promyelocytic leukemia. However, remissions are short-lived because the treatment fails to induce complete differentiation and fails to eradicate the malignant clone. To eliminate rapidly the malignant clone, in analogy with aggressive chemotherapy, the combination of potent differentiation- and apoptosis-inducing drugs working through different receptors and signal pathways may be useful. The active form of vitamin D3 (1,25-dihydroxyvitamin D3; 1,25(OH)2D3) inhibits proliferation and induces differentiation of myeloid leukemic cells. The 9-cis-RA, unlike all-trans-RA which binds only retinoic acid receptors, is a high affinity ligand for both retinoic acid receptors and retinoid X receptors. The aim of this study was to evaluate the therapeutic potential of combining a vitamin D(3) analogue, 20-epi-22-oxa-24a,26a,27a-tri-homo-1alpha,25(OH) 2D, (KH 1060), which belongs to the family of potent 20-epi-1,25(OH),D3 analogues, with 9-cis-RA by assessing their effects on the proliferation, differentiation, and apoptosis of the human leukemia cell line HL-60 in vitro. Our data show that KH 1060 alone is a very potent inhibitor of clonal proliferation of HL-60, but this effect is reversible, and that 9-cis-RA alone is a weak inhibitor of clonal proliferation of HL-60 cells. In contrast, the combination of KH 1060 and 9-cis-RA synergistically and irreversibly inhibited the clonal proliferation of HL-60 cells and induced apoptosis, as detected by morphological changes and DNA fragmentation. This combination also affected the expression of apoptosis-related genes. The bcl-2 protein became nearly undetectable, and expression of bax protein increased slightly (the bax:bcl-2 ratio was 14-fold higher than in untreated cells). Differentiation of treated HL-60 cells was assessed by their ability to produce superoxide, as measured by reduction of nitro blue tetrazolium, positive staining for alpha-naphthyl acetate esterase, phagocytosis, morphology, and analysis of membrane-bound differentiation markers with two-color immunofluorescence. Treatment with the combination of KH 1060 and 9-cis-RA was a potent inducer of differentiation of HL-60, with the cells developing a myelomonocytic phenotype. In summary, our data demonstrate that the combination of both KH 1060 and 9-cis-RA irreversibly and synergistically inhibited clonal growth, induced differentiation and apoptosis of HL-60 cells concomitantly with a very marked decreased expression of bcl-2, and increased the bax:bcl-2 ratio. This drug combination may have important therapeutic significance