title: Methylation-dependent SOX9 expression mediates invasion in human melanoma cells and is a negative prognostic factor in advanced melanoma.
abstract: BACKGROUND
  Melanoma is the most fatal skin cancer displaying a high degree of molecular heterogeneity. Phenotype switching is a mechanism that contributes to melanoma heterogeneity by altering transcription profiles for the transition between states of proliferation/differentiation and invasion/stemness. As phenotype switching is reversible, epigenetic mechanisms, like DNA methylation, could contribute to the changes in gene expression.
  
  
  RESULTS
  Integrative analysis of methylation and gene expression datasets of five proliferative and five invasion melanoma cell cultures reveal two distinct clusters. SOX9 is methylated and lowly expressed in the highly proliferative group. SOX9 overexpression results in decreased proliferation but increased invasion in vitro. In a B16 mouse model, sox9 overexpression increases the number of lung metastases. Transcriptional analysis of SOX9-overexpressing melanoma cells reveals enrichment in epithelial to mesenchymal transition (EMT) pathways. Survival analysis of The Cancer Genome Atlas melanoma dataset shows that metastatic patients with high expression levels of SOX9 have significantly worse survival rates. Additional survival analysis on the targets of SOX9 reveals that most SOX9 downregulated genes have survival benefit for metastatic patients.
  
  
  CONCLUSIONS
  Our genome-wide DNA methylation and gene expression study of 10 early passage melanoma cell cultures reveals two phenotypically distinct groups. One of the genes regulated by DNA methylation between the two groups is SOX9. SOX9 induces melanoma cell invasion and metastasis and decreases patient survival. A number of genes downregulated by SOX9 have a negative impact on patient survival. In conclusion, SOX9 is an important gene involved in melanoma invasion and negatively impacts melanoma patient survival.
authors.affiliation: Department of Dermatology, Faculty of Medicine, University Hospital Zürich, and University of Zürich, Wagistrasse 14, CH-8952, Zürich, Switzerland. phil.cheng@usz.ch.
authors.forename: Phil F
authors.initials: PF
authors.lastname: Cheng
authors.affiliation: Cell and Developmental Biology, Institute of Anatomy, University of Zürich, Zürich, Switzerland. olga.shakhova@usz.ch.
authors.forename: Olga
authors.initials: O
authors.lastname: Shakhova
authors.affiliation: Department of Dermatology, Faculty of Medicine, University Hospital Zürich, and University of Zürich, Wagistrasse 14, CH-8952, Zürich, Switzerland. daniel.widmer@usz.ch.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Widmer
authors.affiliation: Department of Dermatology, Faculty of Medicine, University Hospital Zürich, and University of Zürich, Wagistrasse 14, CH-8952, Zürich, Switzerland. ossia.eichhoff@usz.ch.
authors.forename: Ossia M
authors.initials: OM
authors.lastname: Eichhoff
authors.affiliation: Cell and Developmental Biology, Institute of Anatomy, University of Zürich, Zürich, Switzerland. daniel.zingg@uzh.ch.
authors.forename: Daniel
authors.initials: D
authors.lastname: Zingg
authors.affiliation: Institute of Veterinary Biochemistry and Molecular Biology, University of Zürich, Zürich, Switzerland. sandra.frommel@vetbio.uzh.ch.
authors.forename: Sandra C
authors.initials: SC
authors.lastname: Frommel
authors.affiliation: Department of Dermatology, Faculty of Medicine, University Hospital Zürich, and University of Zürich, Wagistrasse 14, CH-8952, Zürich, Switzerland. benedetta.belloni@lrz.tum.de.
authors.forename: Benedetta
authors.initials: B
authors.lastname: Belloni
authors.affiliation: Department of Dermatology, Faculty of Medicine, University Hospital Zürich, and University of Zürich, Wagistrasse 14, CH-8952, Zürich, Switzerland. marieke.raaijmakers@usz.ch.
authors.forename: Marieke Ig
authors.initials: MI
authors.lastname: Raaijmakers
authors.affiliation: Department of Dermatology, Faculty of Medicine, University Hospital Zürich, and University of Zürich, Wagistrasse 14, CH-8952, Zürich, Switzerland. simone.goldinger@usz.ch.
authors.forename: Simone M
authors.initials: SM
authors.lastname: Goldinger
authors.affiliation: Institute of Veterinary Biochemistry and Molecular Biology, University of Zürich, Zürich, Switzerland. raffaella.santoro@vetbio.uzh.ch.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Santoro
authors.affiliation: Faculty of Mathematics and Natural Sciences, Institute of Molecular Life Sciences, University of Zürich, Zürich, Switzerland. silvio.hemmi@imls.uzh.ch.
authors.forename: Silvio
authors.initials: S
authors.lastname: Hemmi
authors.affiliation: Cell and Developmental Biology, Institute of Anatomy, University of Zürich, Zürich, Switzerland. lukas.sommer@anatom.uzh.ch.
authors.forename: Lukas
authors.initials: L
authors.lastname: Sommer
authors.affiliation: Department of Dermatology, Faculty of Medicine, University Hospital Zürich, and University of Zürich, Wagistrasse 14, CH-8952, Zürich, Switzerland. reinhard.dummer@usz.ch.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Dummer
authors.affiliation: Department of Dermatology, Faculty of Medicine, University Hospital Zürich, and University of Zürich, Wagistrasse 14, CH-8952, Zürich, Switzerland. mitchellpaul.levesque@usz.ch.
authors.forename: Mitchell P
authors.initials: MP
authors.lastname: Levesque
mesh_terms: D000368:Aged; D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D008545:Melanoma / Q000235:genetics* / Q000473:pathology; D051379:Mice; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000235:genetics* / Q000473:pathology; D009367:Neoplasm Staging; D011379:Prognosis; D055758:SOX9 Transcription Factor / Q000096:biosynthesis* / Q000235:genetics; D015398:Signal Transduction; D012878:Skin Neoplasms / Q000235:genetics* / Q000473:pathology; D016019:Survival Analysis
chemical_list: D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human