title: NOTCH1 mutations associate with low CD20 level in chronic lymphocytic leukemia: evidence for a NOTCH1 mutation-driven epigenetic dysregulation.
abstract: In chronic lymphocytic leukemia (CLL), NOTCH1 mutations have been associated with clinical resistance to the anti-CD20 rituximab, although the mechanisms behind this peculiar behavior remain to be clarified. In a wide CLL series (n=692), we demonstrated that CLL cells from NOTCH1-mutated cases (87/692) were characterized by lower CD20 expression and lower relative lysis induced by anti-CD20 exposure in vitro. Consistently, CD20 expression by CLL cells was upregulated in vitro by γ-secretase inhibitors or NOTCH1-specific small interfering RNA and the stable transfection of a mutated (c.7541-7542delCT) NOTCH1 intracellular domain (NICD-mut) into CLL-like cells resulted in a strong downregulation of both CD20 protein and transcript. By using these NICD-mut transfectants, we investigated protein interactions of RBPJ, a transcription factor acting either as activator or repressor of NOTCH1 pathway when respectively bound to NICD or histone deacetylases (HDACs). Compared with controls, NICD-mut transfectants had RBPJ preferentially complexed to NICD and showed higher levels of HDACs interacting with the promoter of the CD20 gene. Finally, treatment with the HDAC inhibitor valproic acid upregulated CD20 in both NICD-mut transfectants and primary CLL cells. In conclusion, NOTCH1 mutations are associated with low CD20 levels in CLL and are responsible for a dysregulation of HDAC-mediated epigenetic repression of CD20 expression.
authors.affiliation: Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy.
authors.forename: F
authors.initials: F
authors.lastname: Pozzo
authors.affiliation: Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy.
authors.forename: T
authors.initials: T
authors.lastname: Bittolo
authors.affiliation: Immunogenetics Unit, Human Genetics Foundation (HuGeF), Torino, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Arruga
authors.affiliation: Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy.
authors.forename: P
authors.initials: P
authors.lastname: Bulian
authors.affiliation: Department of Life Sciences, University of Trieste, Trieste, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Macor
authors.affiliation: Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy.
authors.forename: E
authors.initials: E
authors.lastname: Tissino
authors.affiliation: Immunogenetics Unit, Human Genetics Foundation (HuGeF), Torino, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Gizdic
authors.affiliation: Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy.
authors.forename: F M
authors.initials: FM
authors.lastname: Rossi
authors.affiliation: Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy.
authors.forename: R
authors.initials: R
authors.lastname: Bomben
authors.affiliation: Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy.
authors.forename: A
authors.initials: A
authors.lastname: Zucchetto
authors.affiliation: Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy.
authors.forename: D
authors.initials: D
authors.lastname: Benedetti
authors.affiliation: Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy.
authors.forename: M
authors.initials: M
authors.lastname: Degan
authors.affiliation: Onco-Hematology Department, Centro di Riferimento Oncologico della Basilicata, I.R.C.C.S., Rionero in Vulture, Italy.
authors.forename: G
authors.initials: G
authors.lastname: D'Arena
authors.affiliation: Division of Hematology, Ferrarotto Hospital, Catania, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Chiarenza
authors.affiliation: Clinica Ematologica, Centro Trapianti e Terapie Cellulari 'Carlo Melzi' DISM, Azienda Ospedaliera Universitaria S. Maria Misericordia, Udine, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Zaja
authors.affiliation: Department of Internal Medicine and Hematology, Maggiore General Hospital, University of Trieste, Trieste, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Pozzato
authors.affiliation: Division of Hematology, Department of Translational Medicine, Amedeo Avogadro University of Eastern Piedmont, Novara, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Rossi
authors.affiliation: Division of Hematology, Department of Translational Medicine, Amedeo Avogadro University of Eastern Piedmont, Novara, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Gaidano
authors.affiliation: Division of Hematology, S. Eugenio Hospital and University of Tor Vergata, Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Del Poeta
authors.affiliation: Immunogenetics Unit, Human Genetics Foundation (HuGeF), Torino, Italy.|Department of Medical Sciences, University of Torino, Torino, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Deaglio
authors.affiliation: Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy.
authors.forename: V
authors.initials: V
authors.lastname: Gattei
authors.affiliation: Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy.
authors.forename: M
authors.initials: M
authors.lastname: Dal Bo
mesh_terms: D018951:Antigens, CD20 / Q000032:analysis*; D044127:Epigenesis, Genetic; D015972:Gene Expression Regulation, Neoplastic; D056284:Histone Deacetylase 1 / Q000032:analysis; D056464:Histone Deacetylase 2 / Q000032:analysis; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006801:Humans; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000378:metabolism; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics* / Q000276:immunology; D009154:Mutation; D051881:Receptor, Notch1 / Q000235:genetics*
chemical_list: D018951:Antigens, CD20; D056572:Histone Deacetylase Inhibitors; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; C497761:NOTCH1 protein, human; C497570:RBPJ protein, human; D051881:Receptor, Notch1; C110550:HDAC1 protein, human; C533423:HDAC2 protein, human; D056284:Histone Deacetylase 1; D056464:Histone Deacetylase 2