DNA hypomethylation at the ZNF206-exon 5 CpG island associated with neuronal differentiation in mice and development of neuroblastoma in humans.

Differentiation of human neuroblastoma recapitulates neural crest development. In our whole genome DNA methylation screening of tissue-specific differentially methylated regions (T-DMRs) and developmental stage specific differentially methylated regions (DS-DMRs) we reported that the exon 5 CpG island (CpGi) of Zfp206 (human: ZNF206), which was required to maintain embryonic stem cells in a pluripotent state, was one of potent brain and testis-specific T-DMRs in mice. In this study methylation level of the CpG sites at Zfp206-exon 5 CpGi in mouse brain samples at three different developmental stages (15-day-old embryo; E15, new born; NB, 12-week adult; AD) were quantitatively analyzed and it was identified that Zfp206-exon 5 CpGi was the DS-DMRs in mouse brain. In AD brains, Zfp206-exon 5 CpGi was significantly hypomethylated and Zfp206 expression was repressed, compared with E15 and NB brains. Hence, methylation level of human 5'-end of CpGi at ZNF206-exon 5, which is homologous CpGi to mice, was analyzed in neuroblastomas. Although all four adrenal samples showed complete methylation at the homologous region, we found the hypomethylation in 7 out of 26 neuroblastomas and a significant association between the hypomethylation and poor prognosis. In neuroblastoma cell lines and specimens, the hypomethylation was also associated with ZNF206 expression. These data indicated that the changes in DNA methylation levels at the Zfp206-exon 5 might be one of the important factors during neuronal development in mice and that the hypomethylation of the homologous region induced ZNF206 expression in humans and was associated with human neuroblastomagenesis. Even though the function of ZNF206 and its expression regulation in neuroblastoma remain elusive, ZNF206 might be a candidate differentiation suppressor and prognosis marker in neuroblastoma.