title: Mining gene expression signature for the detection of pre-malignant melanocytes and early melanomas with risk for metastasis.
abstract: BACKGROUND
  Metastatic melanoma is a highly aggressive skin cancer and currently resistant to systemic therapy. Melanomas may involve genetic, epigenetic and metabolic abnormalities. Evidence is emerging that epigenetic changes might play a significant role in tumor cell plasticity and metastatic phenotype of melanoma cells.
  
  
  RESULTS
  In this study, we developed a systematic approach to identify genes implicated in melanoma progression. To do this, we used the Affymetrix GeneChip Arrays to screen 34,000 mouse transcripts in melan-a melanocytes, 4C pre-malignant melanocytes, 4C11- non-metastatic and 4C11+ metastatic melanoma cell lines. The genome-wide association studies revealed pathways commonly over-represented in the transition from immortalized to pre-malignant stage, and under-represented in the transition from non-metastatic to metastatic stage. Additionally, the treatment of cells with 10 µM 5-aza-2'-deoxycytidine (5AzaCdR) for 48 hours allowed us to identify genes differentially re-expressed at specific stages of melan-a malignant transformation. Treatment of human primary melanocytes with the demethylating agent 5AzaCdR in combination to the histone deacetylase inhibitor Trichostatin A (TSA) revealed changes on melanocyte morphology and gene expression which could be an indicator of epigenetic flexibility in normal melanocytes. Moreover, changes on gene expression recognized by affecting the melanocyte biology (NDRG2 and VDR), phenotype of metastatic melanoma cells (HSPB1 and SERPINE1) and response to cancer therapy (CTCF, NSD1 and SRC) were found when Mel-2 and/or Mel-3-derived patient metastases were exposed to 5AzaCdR plus TSA treatment. Hierarchical clustering and network analyses in a panel of five patient-derived metastatic melanoma cells showed gene interactions that have never been described in melanomas.
  
  
  CONCLUSIONS
  Despite the heterogeneity observed in melanomas, this study demonstrates the utility of our murine melanoma progression model to identify molecular markers commonly perturbed in metastasis. Additionally, the novel gene expression signature identified here may be useful in the future into a model more closely related to translational research.
authors.affiliation: Departamento de Farmacologia, Universidade Federal de São Paulo, São Paulo, São Paulo, Brazil.
authors.forename: Camila Ferreira
authors.initials: CF
authors.lastname: de Souza
authors.forename: Patrícia
authors.initials: P
authors.lastname: Xander
authors.forename: Ana Carolina
authors.initials: AC
authors.lastname: Monteiro
authors.forename: Amanda Gonçalves dos Santos
authors.initials: AG
authors.lastname: Silva
authors.forename: Débora Castanheira Pereira
authors.initials: DC
authors.lastname: da Silva
authors.forename: Sabine
authors.initials: S
authors.lastname: Mai
authors.forename: Viviane
authors.initials: V
authors.lastname: Bernardo
authors.forename: José Daniel
authors.initials: JD
authors.lastname: Lopes
authors.forename: Miriam Galvonas
authors.initials: MG
authors.lastname: Jasiulionis
mesh_terms: D000818:Animals; D001374:Azacitidine / Q000031:analogs & derivatives / Q000378:metabolism; D045744:Cell Line, Tumor; D018450:Disease Progression; D044127:Epigenesis, Genetic; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D007621:Karyotyping; D008544:Melanocytes / Q000166:cytology / Q000378:metabolism*; D008545:Melanoma / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009362:Neoplasm Metastasis; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D012306:Risk; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism*
chemical_list: D006877:Hydroxamic Acids; C012589:trichostatin A; C041519:5-aza-2'-deoxycytidine-5'-monophosphate; D001374:Azacitidine