title: RUNX1/ETO blocks selectin-mediated adhesion via epigenetic silencing of PSGL-1.
abstract: RUNX1/ETO (RE), the t(8;21)-derived leukemic transcription factor associated with acute myeloid leukemia (AML) development, deregulates genes involved in differentiation, self-renewal and proliferation. In addition, these cells show differences in cellular adhesion behavior whose molecular basis is not well understood. Here, we demonstrate that RE epigenetically silences the gene encoding P-Selectin Glycoprotein Ligand-1 (PSGL-1) and downregulates PSGL-1 expression in human CD34+ and murine lin- hematopoietic progenitor cells. Levels of PSGL-1 inversely and dose-dependently correlate with RE oncogene levels. However, a DNA-binding defective mutant fails to downregulate PSGL-1. We show by ChIP experiments that the PSGL-1 promoter is a direct target of RE and binding is accompanied by high levels of the repressive chromatin mark histone H3K27me3. In t(8;21)+ Kasumi-1 cells, PSGL-1 expression is completely restored at both the mRNA and cell surface protein levels following RE downregulation with short hairpin RNA (shRNA) or RE inhibition with tetramerization-blocking peptides, and at the promoter H3K27me3 is replaced by the activating chromatin mark H3K9ac as well as by RNA polymerase II. Upregulation of PSGL-1 restores the binding of cells to P- and E-selectin and re-establishes myeloid-specific cellular adhesion while it fails to bind to lymphocyte-specific L-selectin. Overall, our data suggest that the RE oncoprotein epigenetically represses PSGL-1 via binding to its promoter region and thus affects the adhesive behavior of t(8;21)+ AML cells.
authors: 1] Department of Transfusion Medicine, Cell Therapeutics and Hemostaseology, Ludwig-Maximilian University Hospital, Munich, Germany [2] Institute of Transfusion Medicine and Immunohematology, Goethe University, Frankfurt, Germany.
authors: K
authors: K
authors: Ponnusamy
authors: Institute for Tumor Biology and Experimental Therapy, Georg-Speyer-Haus, Frankfurt, Germany.
authors: N
authors: N
authors: Kohrs
authors: School of Cancer Sciences, University of Birmingham, Birmingham, UK.
authors: A
authors: A
authors: Ptasinska
authors: School of Cancer Sciences, University of Birmingham, Birmingham, UK.
authors: S A
authors: SA
authors: Assi
authors: Department of Internal Medicine 3, Ludwig-Maximilian University Hospital, Munich, Germany.
authors: T
authors: T
authors: Herold
authors: Department of Internal Medicine 3, Ludwig-Maximilian University Hospital, Munich, Germany.
authors: W
authors: W
authors: Hiddemann
authors: Institute for Tumor Biology and Experimental Therapy, Georg-Speyer-Haus, Frankfurt, Germany.
authors: J
authors: J
authors: Lausen
authors: School of Cancer Sciences, University of Birmingham, Birmingham, UK.
authors: C
authors: C
authors: Bonifer
authors: 1] Department of Transfusion Medicine, Cell Therapeutics and Hemostaseology, Ludwig-Maximilian University Hospital, Munich, Germany [2] Institute of Transfusion Medicine and Immunohematology, Goethe University, Frankfurt, Germany.
authors: R
authors: R
authors: Henschler
authors: 1] Department of Transfusion Medicine, Cell Therapeutics and Hemostaseology, Ludwig-Maximilian University Hospital, Munich, Germany [2] Institute for Tumor Biology and Experimental Therapy, Georg-Speyer-Haus, Frankfurt, Germany.
authors: C
authors: C
authors: Wichmann