title: A role for serine proteases in mediating phorbol ester-induced differentiation of HL-60 cells.
abstract: Treatment of human HL-60 promyelocytic leukemia cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) results in increases in proteolytic activity and maturation toward the monocytic lineage. To investigate the potential roles that different classes of proteases play in the monocytic differentiation of HL-60 cells, cells were treated with phorbol ester in the presence of various serine and cysteine protease inhibitors. The serine protease inhibitors 4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF), N-alpha-tosyl-phenylalanine chloromethyl ketone (TPCK), and N-alpha-tosyl-lysine chloromethyl ketone (TLCK) repressed a number of phenotypic markers of monocytic differentiation including surface expression of the CD11b integrin, cell aggregate formation, cell cycle exit, and cell death. CD11b was not detected at the cell surface by FACS analysis up to 24 h after induction of differentiation; however, both CD11b mRNA and protein were present. Downregulation of c-myc mRNA and upregulation of c-fos and egr-1 mRNA and protein, which normally occur during TPA-induced differentiation, were not affected by inclusion of the protease inhibitors. These data indicate that serine proteases specifically mediate many of the phenotypic aspects of TPA-induced monocytic differentiation but are not involved with the induction or repression of differentiation-sensitive transcription factors and suggest that serine protease activity is required for intracellular processing of CD11b.
authors.affiliation: Departments of Biochemistry & Molecular Biology and Oncology, The University of Calgary Health Sciences Centre, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada.
authors.forename: L J
authors.initials: LJ
authors.lastname: Bestilny
authors.forename: K T
authors.initials: KT
authors.lastname: Riabowol
mesh_terms: D015703:Antigens, CD / Q000235:genetics / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D018922:HL-60 Cells; D006801:Humans; D007700:Kinetics; D016177:Macrophage-1 Antigen / Q000235:genetics / Q000502:physiology; D012697:Serine Endopeptidases / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D013450:Sulfones / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014107:Tosyllysine Chloromethyl Ketone / Q000494:pharmacology; D014108:Tosylphenylalanyl Chloromethyl Ketone / Q000494:pharmacology; D014158:Transcription, Genetic
chemical_list: D015703:Antigens, CD; D015853:Cysteine Proteinase Inhibitors; D016177:Macrophage-1 Antigen; D015842:Serine Proteinase Inhibitors; D013450:Sulfones; D014107:Tosyllysine Chloromethyl Ketone; C002010:4-(2-aminoethyl)benzenesulfonylfluoride; D014108:Tosylphenylalanyl Chloromethyl Ketone; D012697:Serine Endopeptidases; D013755:Tetradecanoylphorbol Acetate