Global DNA methylation in fetal human germ cells and germ cell tumours: association with differentiation and cisplatin resistance |
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| Authors: | Hendrik Wermann Hans Stoop Ad JM Gillis Friedemann Honecker Ruud JHLM van Gurp Ole Ammerpohl Julia Richter J Wolter Oosterhuis Carsten Bokemeyer Leendert HJ Looijenga |
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| Affiliation: | 1. Department of Pathology, Erasmus MC—Erasmus University Medical Center, Daniel den Hoed Cancer Center, Josephine Nefkens Institute, 3000 CA Rotterdam, The Netherlands;2. Department of Oncology, Hematology, Bone Marrow Transplantation within Section of Pneumology, University Medical Center Hamburg‐Eppendorf, 20246 Hamburg, Germany;3. Statement of author contributions;4. HW, HS, AG, RvG, OA, and JR conceived and carried out experiments. FH, JWO, CB, and LL conceived experiments and analysed data. All authors were involved in writing the paper and had final approval of the submitted and published versions.;5. Institute of Human Genetics, Christian‐Albrechts University Kiel/University Hospital Schleswig‐Holstein Campus Kiel, 24105 Kiel, Germany |
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| 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‐ 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. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. |
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| Keywords: | germ cell tumours DNA methylation differentiation cisplatin resistance 5‐azacytidine |
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