title: Cytokine-mediated erythroid maturation in megakaryoblastic human cell line HU-3.
abstract: HU-3 is a bipotential cell line derived from the bone marrow of a patient with megakaryoblastic leukemia. Continuously proliferating cells evolved from cultures supplemented with nutrient medium containing human serum and granulocyte-macrophage (GM) colony-stimulating factor (CSF). Growth and viability of the HU-3 cell line was strictly dependent on the presence of GM-CSF, interleukin-3, or thrombopoietin (Tpo). Independent of the cytokine, the cells constitutively expressed a well-defined megakaryocyte phenotype, with 70-95% of the cells positive for CD4, CD34, and platelet glycoproteins Ib, IIb, and IIIa. Fewer than 10% of the cells had detectable erythroid glycophorin A. Erythropoiesis was induced in HU-3 parental cells and five clones harvested from culture medium containing GM-CSF by replacement of the growth-promoting cytokine with stem cell factor (SCF) and erythropoietin (Epo). During the first week of induction, the proliferating cells slowly acquired erythroid markers. Concomitant with a maturational growth arrest during the second week, there was a rapid accumulation of gamma and beta globin chains and benzidine reactive hemoglobin, as well as a distinct erythroid morphology. The culture declined after 12 days because of the transient effect of SCF in maintaining viability. Parental and cloned cells cultured for 7 days in Tpo-supplemented medium responded to the synergistic growth effect of SCF and Epo but were markedly suppressed in their yield of hemoglobinized cells. Recycling of the cells in GM-CSF for 4 days did not reverse the suppressive effect of Tpo. These results suggest a role for Tpo in the lineage commitment of erythromegakaryocytic progenitors by suppressing the erythroid potential. With its constitutive megakaryocyte phenotype and inducible erythroid potential, the self-renewing bipotential HU-3 cell line may represent one of the earliest stages in megakaryocytopoiesis before irreversible lineage commitment. The suppressive effect of Tpo on the erythroid potential of cloned HU-3 cells enhances the value of this cell line for deciphering the molecular and cellular events during lineage commitment of progenitor cells.
authors.affiliation: Department of Medicine, Allegheny University of the Health Sciences, Philadelphia, PA 19102, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Morgan
authors.forename: R
authors.initials: R
authors.lastname: Class
authors.forename: G
authors.initials: G
authors.lastname: Soslau
authors.forename: I
authors.initials: I
authors.lastname: Brodsky
mesh_terms: D002455:Cell Division / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000187:drug effects; D003582:Cytogenetics; D016207:Cytokines / Q000494:pharmacology*; D004920:Erythropoiesis / Q000187:drug effects / Q000502:physiology*; D004921:Erythropoietin / Q000494:pharmacology; D005434:Flow Cytometry; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D007947:Leukemia, Megakaryoblastic, Acute / Q000473:pathology; D019089:Stem Cell Factor / Q000494:pharmacology; D013926:Thrombopoietin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D016207:Cytokines; D019089:Stem Cell Factor; D004921:Erythropoietin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D013926:Thrombopoietin