title: Hypermethylation of genes in testicular embryonal carcinomas.
abstract: BACKGROUND
  Testicular embryonal carcinoma (EC) is a major subtype of non-seminomatous germ cell tumours in males. Embryonal carcinomas are pluripotent, undifferentiated germ cell tumours believed to originate from primordial germ cells. Epigenetic changes during testicular EC tumorigenesis require better elucidation.
  
  
  METHODS
  To identify epigenetic changes during testicular neoplastic transformation, we profiled DNA methylation of six ECs. These samples represent different stages (stage I and stage III) of divergent invasiveness. Non-cancerous testicular tissues were included. Expression of a number of hypermethylated genes were examined by quantitative RT-PCR and immunohistochemistry (IHC).
  
  
  RESULTS
  A total of 1167 tumour-hypermethylated differentially methylated regions (DMRs) were identified across the genome. Among them, 40 genes/ncRNAs were found to have hypermethylated promoters. Quantitative RT-PCR confirmed downregulation of 8 out of 9 of the genes. Among the confirmed genes, five were sex-linked genes, including X-linked genes STAG2, SPANXD/E and MIR1184, and Y-linked genes RBMY1A1/1B/1D and FAM197Y2P. RBMY1A is a testis-specific gene for spermatogenesis. RNF168 and USP13 are potential tumour suppressors. Expression of RBMY1A was lost in EC and seminoma as documented in the Protein Atlas. We confirmed downregulation of USP13 in EC by IHC.
  
  
  CONCLUSIONS
  Our genome-wide analysis of testicular EC identified methylation changes in several previously unknown genes. This may provide insight of crosstalk between normal germ cell development and carcinogenesis.
authors.affiliation: The Chinese University of Hong Kong-Shandong University Joint Laboratory on Reproductive Genetics, School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
authors.forename: Hoi-Hung
authors.initials: HH
authors.lastname: Cheung
authors.affiliation: Key Laboratory of Fertility Preservation and Maintenance, Ministry of Education, Key Laboratory of Reproduction and Genetics in Ningxia, Ningxia Medical University, Ningxia 750004, China.
authors.forename: Yanzhou
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Reproduction, Development and Endocrinology Theme, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
authors.forename: Tin-Lap
authors.initials: TL
authors.lastname: Lee
authors.affiliation: The Eunice Kennedy Shriver National Institute of Child Health & Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Owen
authors.initials: O
authors.lastname: Rennert
authors.affiliation: The Chinese University of Hong Kong-Shandong University Joint Laboratory on Reproductive Genetics, School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.|Reproduction, Development and Endocrinology Theme, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
authors.forename: Wai-Yee
authors.initials: WY
authors.lastname: Chan
mesh_terms: D000217:Acyltransferases / Q000235:genetics; D000293:Adolescent; D000328:Adult; D018236:Carcinoma, Embryonal / Q000235:genetics* / Q000473:pathology; D016022:Case-Control Studies; D015331:Cohort Studies; D019175:DNA Methylation; D010450:Endopeptidases / Q000235:genetics; D044127:Epigenesis, Genetic; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009687:Nuclear Proteins / Q000235:genetics; D011401:Promoter Regions, Genetic; D016601:RNA-Binding Proteins / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D013736:Testicular Neoplasms / Q000235:genetics* / Q000473:pathology; D046888:Tissue Array Analysis; D044767:Ubiquitin-Protein Ligases / Q000235:genetics; D064570:Ubiquitin-Specific Proteases; D055815:Young Adult
chemical_list: D009687:Nuclear Proteins; C501499:RBMY1A1 protein, human; D016601:RNA-Binding Proteins; C521016:SPANXD protein, human; D000217:Acyltransferases; C018764:2-acylglycerophosphate acyltransferase; C535210:RNF168 protein, human; D044767:Ubiquitin-Protein Ligases; D010450:Endopeptidases; C561638:USP13 protein, human; D064570:Ubiquitin-Specific Proteases