title: Deciphering the Role of Oncogenic MITFE318K in Senescence Delay and Melanoma Progression.
abstract: MITF encodes an oncogenic lineage-specific transcription factor in which a germline mutation ( MITFE318K ) was identified in human patients predisposed to both nevus formation and, among other tumor types, melanoma. The molecular mechanisms underlying the oncogenic activity of MITF E318K remained uncharacterized.
  
  
  
  Here, we compared the SUMOylation status of endogenous MITF by proximity ligation assay in melanocytes isolated from wild-type (n = 3) or E318K (n = 4) MITF donors. We also used a newly generated Mitf E318K knock-in (KI) mouse model to assess the role of Mitf E318K (n = 7 to 13 mice per group) in tumor development in vivo and performed transcriptomic analysis of the tumors to identify the molecular mechanisms. Finally, using immortalized or normal melanocytes (wild-type or E318K MITF, n = 2 per group), we assessed the role of MITF E318K on the induction of senescence mediated by BRAF V600E . All statistical tests were two-sided.
  
  
  
  We demonstrated a decrease in endogenous MITF SUMOylation in melanocytes from MITF E318K patients (mean of cells with hypoSUMOylated MITF, MITF E318K vs MITF WT , 94% vs 44%, difference = 50%, 95% CI = 21.8% to 67.2%, P  = .004). The Mitf E318K mice were slightly hypopigmented (mean melanin content Mitf WT vs Mitf E318K/+ , 0.54 arbitrary units [AU] vs 0.36 AU, difference = -0.18, 95% CI = -0.36 to -0.007, P  = .04). We provided genetic evidence that Mitf E318K enhances BRaf V600E -induced nevus formation in vivo (mean nevus number for Mitf E318K , BRaf V600E vs Mitf WT , BRaf V600E , 68 vs 44, difference = 24, 95% CI = 9.1 to 38.9, P  = .006). Importantly, although Mitf E318K was not sufficient to cooperate with BRaf V600E alone in promoting metastatic melanoma, it accelerated tumor formation on a BRaf V600E , Pten-deficient background (median survival, Mitf E318K/+  = 42 days, 95% CI = 31 to 46 vs Mitf WT  = 51 days, 95% CI = 50 to 55, P  < .001). Transcriptome analysis suggested a decrease in senescence in tumors from Mitf E318K mice. We confirmed this hypothesis by in vitro experiments, demonstrating that Mitf E318K impaired the ability of human melanocytes to undergo BRAF V600E -induced senescence.
  
  
  
  We characterized the functions of melanoma-associated MITF E318K mutations. Our results demonstrate that MITF E318K reduces the program of senescence to potentially favor melanoma progression in vivo.
authors.affiliation: INSERM, U1065 (équipe 1), Equipe labélisée ARC 2016, C3M, Nice, France.|University of Nice Sophia-Antipolis, UFR Médecine, Nice, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Bonet
authors.affiliation: Center for Human Genetics, KU Leuven, Leuven, Belgium.|Center for the Biology of Disease, VIB, Leuven, Belgium.
authors.forename: Flavie
authors.initials: F
authors.lastname: Luciani
authors.affiliation: INSERM, U1065 (équipe 1), Equipe labélisée ARC 2016, C3M, Nice, France.|University of Nice Sophia-Antipolis, UFR Médecine, Nice, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Ottavi
authors.affiliation: INSERM, U1065 (équipe 1), Equipe labélisée ARC 2016, C3M, Nice, France.|University of Nice Sophia-Antipolis, UFR Médecine, Nice, France.
authors.forename: Justine
authors.initials: J
authors.lastname: Leclerc
authors.affiliation: Service de Génétique, Institut de Cancérologie Gustave Roussy, Villejuif, France.
authors.forename: Fanélie-Marie
authors.initials: FM
authors.lastname: Jouenne
authors.affiliation: INSERM, U1065 (équipe 1), Equipe labélisée ARC 2016, C3M, Nice, France.|University of Nice Sophia-Antipolis, UFR Médecine, Nice, France.
authors.forename: Marina
authors.initials: M
authors.lastname: Boncompagni
authors.affiliation: INSERM, U1065 (équipe 1), Equipe labélisée ARC 2016, C3M, Nice, France.|University of Nice Sophia-Antipolis, UFR Médecine, Nice, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Bille
authors.affiliation: University of Nice Sophia-Antipolis, UFR Médecine, Nice, France.|Inserm, ERI21/EA 4319, Nice, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Hofman
authors.affiliation: CNRS-UMR 5535, Montpellier, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Bossis
authors.affiliation: INSERM, U1065 (équipe 12), C3M, Nice, France.
authors.forename: Gian
authors.initials: G
authors.lastname: Marco de Donatis
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS, INSERM, Université de Strasbourg, Illkirch, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Strub
authors.affiliation: INSERM, U1065 (équipe 1), Equipe labélisée ARC 2016, C3M, Nice, France.|University of Nice Sophia-Antipolis, UFR Médecine, Nice, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Cheli
authors.affiliation: INSERM, U1065 (équipe 1), Equipe labélisée ARC 2016, C3M, Nice, France.|University of Nice Sophia-Antipolis, UFR Médecine, Nice, France.
authors.forename: Mickaël
authors.initials: M
authors.lastname: Ohanna
authors.affiliation: INSERM, U1065 (équipe 2), C3M, Nice, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Luciano
authors.affiliation: INSERM, U1065 (équipe 2), C3M, Nice, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Marchetti
authors.affiliation: INSERM, U1065 (équipe 1), Equipe labélisée ARC 2016, C3M, Nice, France.|University of Nice Sophia-Antipolis, UFR Médecine, Nice, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Rocchi
authors.affiliation: INSERM, U1065 (équipe 1), Equipe labélisée ARC 2016, C3M, Nice, France.|Institut Clinique de la Souris-Mouse Clinical Institute, Illkirch, France.
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Birling
authors.affiliation: AP-HP, Hôpital Cochin -Tarnier, Service de Dermatologie et Faculté Paris Descartes, Paris, France.
authors.forename: Marie-Françoise
authors.initials: MF
authors.lastname: Avril
authors.affiliation: Centre Hospitalier Universitaire de Lyon, Department of Dermatology, Lyon, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Poulalhon
authors.affiliation: Centre Hospitalier Universitaire de Lyon, Department of Dermatology, Lyon, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Luc
authors.affiliation: University of Nice Sophia-Antipolis, UFR Médecine, Nice, France.|Inserm, ERI21/EA 4319, Nice, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Hofman
authors.affiliation: Centre Hospitalier Universitaire de Nice, Service de Dermatologie, Nice, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Lacour
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS, INSERM, Université de Strasbourg, Illkirch, France.
authors.forename: Irwin
authors.initials: I
authors.lastname: Davidson
authors.affiliation: Service de Génétique, Institut de Cancérologie Gustave Roussy, Villejuif, France.|INSERM U1186, Immunologie intégrative des tumeurs et génétique oncologique, Paris, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Bressac-de Paillerets
authors.affiliation: INSERM, U1065 (équipe 1), Equipe labélisée ARC 2016, C3M, Nice, France.|University of Nice Sophia-Antipolis, UFR Médecine, Nice, France.
authors.forename: Robert
authors.initials: R
authors.lastname: Ballotti
authors.affiliation: Center for Human Genetics, KU Leuven, Leuven, Belgium.|Center for the Biology of Disease, VIB, Leuven, Belgium.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Marine
authors.affiliation: INSERM, U1065 (équipe 1), Equipe labélisée ARC 2016, C3M, Nice, France.|University of Nice Sophia-Antipolis, UFR Médecine, Nice, France.
authors.forename: Corine
authors.initials: C
authors.lastname: Bertolotto
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D045744:Cell Line, Tumor; D016922:Cellular Senescence / Q000235:genetics; D004195:Disease Models, Animal; D018095:Germ-Line Mutation; D006801:Humans; D008544:Melanocytes; D008545:Melanoma / Q000235:genetics*; D051379:Mice; D051739:Microphthalmia-Associated Transcription Factor / Q000235:genetics* / Q000378:metabolism*; D008875:Middle Aged; D009506:Nevus / Q000235:genetics*; D051059:PTEN Phosphohydrolase / Q000235:genetics; D061251:Primary Cell Culture; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D012878:Skin Neoplasms / Q000235:genetics*; D058207:Sumoylation; D059467:Transcriptome
chemical_list: D051739:Microphthalmia-Associated Transcription Factor; D048493:Proto-Oncogene Proteins B-raf; D051059:PTEN Phosphohydrolase