Global dna hypomethylation in epithelial ovarian cancer: Passive demethylation and association with genomic instability

Wa Zhang, David Klinkebiel, Carter J. Barger, Sanjit Pandey, Chittibabu Guda, Austin Miller, Stacey N. Akers, Kunle Odunsi, Adam R. Karpf

Research output: Contribution to journalArticle

Abstract

A hallmark of human cancer is global DNA hypomethylation (GDHO), but the mechanisms accounting for this defect and its pathological consequences have not been investigated in human epithelial ovarian cancer (EOC). In EOC, GDHO was associated with advanced disease and reduced overall and disease-free survival. GDHO (+) EOC tumors displayed a proliferative gene expression signature, including FOXM1 and CCNE1 overexpression. Furthermore, DNA hypomethylation in these tumors was enriched within genomic blocks (hypomethylated blocks) that overlapped late-replicating regions, lamina-associated domains, PRC2 binding sites, and the H3K27me3 histone mark. Increased proliferation coupled with hypomethylated blocks at late-replicating regions suggests a passive hypomethylation mechanism. This hypothesis was further supported by our observation that cytosine DNA methyltransferases (DNMTs) and UHRF1 showed significantly reduced expression in GDHO (+) EOC after normalization to canonical proliferation markers, including MKI67. Finally, GDHO (+) EOC tumors had elevated chromosomal instability (CIN), and copy number alterations (CNA) were enriched at the DNA hypomethylated blocks. Together, these findings implicate a passive DNA demethylation mechanism in ovarian cancer that is associated with genomic instability and poor prognosis.

Original languageEnglish (US)
Article number764
JournalCancers
Volume12
Issue number3
DOIs
StatePublished - Mar 2020

Keywords

  • DNA hypomethylation
  • DNMTs
  • Epithelial ovarian cancer
  • Gene expression
  • Genomic instability
  • Repetitive elements

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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