title: K562 cells produce and respond to human erythroid-potentiating activity.
abstract: Human erythroid-potentiating activity (EPA) is a 28,000 mol wt glycoprotein that stimulates the growth of erythroid progenitors in vitro and enhances colony formation by the K562 human erythroleukemia cell line. EPA has potent protease inhibitory activity, and is also referred to as tissue inhibitor of metalloproteinases (TIMP). We observed that colony formation by K562 cells in semi-solid medium containing reduced fetal calf serum (FCS) is not directly proportional to the number of cells plated, suggesting production of autostimulatory factors by K562 cells. Using radioimmunoprecipitation and a bioassay for EPA, medium conditioned by K562 cells was found to contain high levels of biologically active EPA; Northern hybridization analysis confirmed the expression of EPA mRNA. Radiolabeled EPA was used to identify cell surface receptors on K562 cells. Together, these results suggest that EPA may act as an autocrine growth factor for K562 cells.
authors.affiliation: Department of Medicine, UCLA School of Medicine.
authors.forename: B R
authors.initials: BR
authors.lastname: Avalos
authors.forename: S E
authors.initials: SE
authors.lastname: Kaufman
authors.forename: M
authors.initials: M
authors.lastname: Tomonaga
authors.forename: R E
authors.initials: RE
authors.lastname: Williams
authors.forename: D W
authors.initials: DW
authors.lastname: Golde
authors.forename: J C
authors.initials: JC
authors.lastname: Gasson
mesh_terms: D000345:Affinity Labels; D002455:Cell Division; D002460:Cell Line; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000473:pathology / Q000503:physiopathology*; D008222:Lymphokines / Q000502:physiology*; D008970:Molecular Weight; D011956:Receptors, Cell Surface / Q000502:physiology*; D019714:Tissue Inhibitor of Metalloproteinases
chemical_list: D000345:Affinity Labels; D008222:Lymphokines; D011956:Receptors, Cell Surface; D019714:Tissue Inhibitor of Metalloproteinases; C056137:erythroid-potentiating activity receptor, human