title: Global DNA methylation in fetal human germ cells and germ cell tumours: association with differentiation and cisplatin resistance.
abstract: Differences in the global methylation pattern, ie hyper- as well as hypo-methylation, are observed in cancers including germ cell tumours (GCTs). Related to their precursor cells, GCT methylation status differs according to histology. We investigated the methylation pattern of normal fetal, infantile, and adult germ cells (n = 103) and GCTs (n = 251) by immunohistochemical staining for 5-(m)cytidine. The global methylation pattern of male germ cells changes from hypomethylation to hypermethylation, whereas female germ cells remain unmethylated at all stages. Undifferentiated GCTs (seminomas, intratubular germ cell neoplasia unclassified, and gonadoblastomas) are hypomethylated, whereas more differentiated GCTs (teratomas, yolk sac tumours, and choriocarcinomas) show a higher degree of methylation. Embryonal carcinomas show an intermediate pattern. Resistance to cisplatin was assessed in the seminomatous cell line TCam-2 before and after demethylation using 5-azacytidine. Exposure to 5-azacytidine resulted in decreased resistance to cisplatin. Furthermore, after demethylation, the stem cell markers NANOG and POU5F1 (OCT3/4), as well as the germ cell-specific marker VASA, showed increased expression. Following treatment with 5-azacytidine, TCam-2 cells were analysed using a high-throughput methylation screen for changes in the methylation sites of 14,000 genes. Among the genes revealing changes, interesting targets were identified: ie demethylation of KLF11, a putative tumour suppressor gene, and hypermethylation of CFLAR, a gene previously described in treatment resistance in GCTs.
authors.affiliation: Department of Pathology, Erasmus MC-Erasmus University Medical Center, Daniel den Hoed Cancer Center, Josephine Nefkens Institute, Rotterdam, The Netherlands.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Wermann
authors.forename: Hans
authors.initials: H
authors.lastname: Stoop
authors.forename: Ad J M
authors.initials: AJ
authors.lastname: Gillis
authors.forename: Friedemann
authors.initials: F
authors.lastname: Honecker
authors.forename: Ruud J H L M
authors.initials: RJ
authors.lastname: van Gurp
authors.forename: Ole
authors.initials: O
authors.lastname: Ammerpohl
authors.forename: Julia
authors.initials: J
authors.lastname: Richter
authors.forename: J Wolter
authors.initials: JW
authors.lastname: Oosterhuis
authors.forename: Carsten
authors.initials: C
authors.lastname: Bokemeyer
authors.forename: Leendert H J
authors.initials: LH
authors.lastname: Looijenga
mesh_terms: D000328:Adult; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D001374:Azacitidine / Q000494:pharmacology; D002454:Cell Differentiation / Q000235:genetics; D002945:Cisplatin / Q000494:pharmacology; D053487:DEAD-box RNA Helicases / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects; D004273:DNA, Neoplasm / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D005333:Fetus / Q000166:cytology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005854:Germ Cells / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D007223:Infant; D008297:Male; D009363:Neoplasm Proteins / Q000378:metabolism; D009373:Neoplasms, Germ Cell and Embryonal / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D010053:Ovary / Q000196:embryology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D018239:Seminoma / Q000235:genetics / Q000378:metabolism; D013736:Testicular Neoplasms / Q000235:genetics / Q000378:metabolism; D013737:Testis / Q000196:embryology
chemical_list: D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; C498288:DDX4 protein, human; D053487:DEAD-box RNA Helicases; D001374:Azacitidine; D002945:Cisplatin