concanavalin-a and Leukemia--Promyelocytic--Acute

In this study we have investigated the link between increased Ca2+ influx rate, acquired upon the differentiation of HL-60 cells, to changes in cytosolic free Ca2+ ([Ca2+]i], evoked by the chemotactic peptide-FMLP and the mitogen Con-A. Although differentiating and undifferentiated HL-60 cells exhibited similar steady-state levels of [Ca2+]i, cells induced to differentiate by dibutyryl-cAMP, at 48 h, exhibited enhanced Ca2+ influx rate, measured by non-steady state 45Ca2+ uptake, and augmentation of FMLP-stimulated Ca2+ influx. At 120 h the above cells responded to FMLP but not to Con-A, by a marked augmentation of Ca2+ influx, and elevated levels of [Ca2+]i. On the other hand HL-60 cells induced to differentiate by retinoic acid responded, as described above, to Con-A but not to FMLP. HL-60 cells grown in the presence of cholera-toxin, were reported to express high levels of FMLP-receptors without expressing cell differentiation. We have demonstrated that, in these cells the Ca2+ influx rate was unchanged, moreover, FMLP-stimulated Ca2+ influx and [Ca2+]i rise were low. These findings strongly suggest that the presence of receptor is not sufficient for FMLP-mediated changes in [Ca2+]i. A link between increased Ca2+ influx rate, acquired upon induction of differentiation, and receptor mediated response in these cells is proposed.

Topics: Bucladesine; Calcium; Cell Differentiation; Cholera Toxin; Concanavalin A; Humans; Kinetics; Leukemia, Promyelocytic, Acute; N-Formylmethionine Leucyl-Phenylalanine; Receptors, Formyl Peptide; Receptors, Immunologic; Tretinoin; Tumor Cells, Cultured

The adenosine analogue 3-deazaadenosine (c3 Ado) induces differentiation of human promyelocytic leukemia HL-60 cells in vitro. c3 Ado affects in vitro viability and growth of cells involved indirectly (cytokine-producing cells) and directly (transformed myeloid cells) in leukemic cell differentiation. Growth inhibition of proliferating cells is achieved at c3 Ado concentrations between 10-100 microM. Concentrations higher than 100 microM affect viability of proliferating and nonproliferating cells.

Topics: Cell Differentiation; Cell Division; Cell Line; Concanavalin A; Dose-Response Relationship, Drug; Hematopoietic Stem Cells; Humans; Leukemia, Promyelocytic, Acute; Lymphocytes; Neoplastic Stem Cells; Stimulation, Chemical; Tubercidin; Tumor Cells, Cultured