title: Thrombospondin-1 (TSP-1) and TSP-1-derived heparin-binding peptides induce promyelocytic leukemia cell differentiation and apoptosis.
abstract: Thrombospondin-1 (TSP-1) is a multifunctional adhesive glycoprotein that is synthesized by several cell types and modulates cell growth and differentiation. In this study, we showed that the amount of TSP-1 secreted by two human leukemia cell lines, HL-60 and NB4, increased markedly during differentiation of these cells by all-trans retinoic acid (ATRA) (10(-7) M), reaching about 100 ng/10(6) cells after 3 days. Addition of purified TSP-1 alone (10(-9)-5 x 10(-8) M) to HL-60 or NB4 cell cultures dose-dependently inhibited cell growth and differentiation. Differently to ATRA, TSP-1-induced differentiation of HL-60 and NB4 cells occurred independently of Bcl-2 regulation, as shown by immunofluorescence and Western immunoblotting. At day 5, TSP-1 also induced promyelocytic leukemia cell apoptosis. The percentage of apoptotic cells in NB4 cultures was higher with TSP-1 (5 x 10(-8) M) than with ATRA (10(-7) M) (46+/-3% versus 19+/-7%, p<0.001), whereas similar levels of apoptosis (37+/-7% and 38+/-6%) were reached with both agents in HL-60 cultures. Studies performed with synthetic peptides derived from the TSP-1 sequence indicated that two heparin-binding peptides, Hep-I and GGWSHW, located within the NH2-terminal and type 1 repeats respectively, were strong inducers of apoptosis of HL-60 and NB4 cells, suggesting that cell surface heparan sulfate molecules might be involved in the apoptotic effect of TSP-1 on promyelocytic cells.
authors.affiliation: Laboratoire Hémostase, Endothélium, Angiogenèse, INSERM Unité 553, IFR 105, Institut Universitaire d'Hématologie Paris 7, Hôpital St Louis, 75475 Paris, France.
authors.forename: Arlette
authors.initials: A
authors.lastname: Bruel
authors.forename: Myriem
authors.initials: M
authors.lastname: Touhami-Carrier
authors.forename: Annick
authors.initials: A
authors.lastname: Thomaidis
authors.forename: Chantal
authors.initials: C
authors.lastname: Legrand
mesh_terms: D000595:Amino Acid Sequence; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects* / Q000502:physiology; D048708:Cell Growth Processes / Q000187:drug effects; D018922:HL-60 Cells; D006493:Heparin / Q000378:metabolism; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D019700:Thrombospondin 1 / Q000378:metabolism / Q000494:pharmacology*; D014212:Tretinoin / Q000494:pharmacology; D051028:bcl-2-Associated X Protein
chemical_list: D000970:Antineoplastic Agents; D010446:Peptide Fragments; D019253:Proto-Oncogene Proteins c-bcl-2; D019700:Thrombospondin 1; D051028:bcl-2-Associated X Protein; D014212:Tretinoin; D006493:Heparin