DNA hypohydroxymethylation in pediatric central nervous system tumors is associated with CTCF binding sites and reduced survival

Abstract

AbstractNucleotide-specific 5-hydroxymethylcytosine (5hmC) remains understudied in pediatric central nervous system tumors. We measured genome-scale 5hmC in glioma, ependymoma, and embryonal tumors from children, as well as control pediatric brain tissues using oxidative and bisulfite treatments. Tumor 5hmC localized to regulatory elements crucial to cell identity, including transcription factor binding sites and super-enhancers. A linear model tested the CpG-specific differences in 5hmC between tumor and non-tumor samples, as well as between tumor subtypes. Compared to non-tumor samples, tumors were hypohydroxymethylated across the epigenome. Differentially hydroxymethylated loci among tumor subtypes tended to be hypermethylated and disproportionally found in CTCF binding sites and genes related to posttranscriptional RNA regulation, such as DICER1. Model-based clustering results indicated that patients with low 5hmC patterns have poorer overall survival and increased risk of recurrence. These results have implications for emerging molecular neuropathology classification approaches and epigenetic therapeutic strategies in childhood brain tumors.