Single CpG site methylation controls estrogen receptor gene transcription and correlates with hormone therapy resistance

Kouki Tsuboi, Takamasa Nagatomo, Tatsuyuki Gohno, Toru Higuchi, Shunta Sasaki, Natsu Fujiki, Masafumi Kurosumi, Hiroyuki Takei, Yuri Yamaguchi, Toshifumi Niwa, Shin ichi Hayashi

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

Hormone therapy is the most effective treatment for patients with estrogen receptor α-positive breast cancers. However, although resistance occurs during treatment in some cases and often reflects changed estrogen receptor α status, the relationship between changes in estrogen receptor α expression and resistance to therapy are poorly understood. In this study, we identified a mechanism for altered estrogen receptor α expression during disease progression and acquired hormone therapy resistance in aromatase inhibitor-resistant breast cancer cell lines. Subsequently, we investigated promoter switching and DNA methylation status of the estrogen receptor α promoter, and found marked changes of methylation at a single CpG site (CpG4) in resistant cells. In addition, luciferase reporter assays showed reduced transcriptional activity from this methylated CpG site. This CpG region was also completely conserved among species, suggesting that it acts as a methylation-sensitive Ets-2 transcription factor binding site, as confirmed using chromatin immunoprecipitation assays. In estrogen receptor α-positive tumors, CpG4 methylation levels were inversely correlated with estrogen receptor α expression status, suggesting that single CpG site plays an important role in the regulation of estrogen receptor α transcription.

Original languageEnglish
Pages (from-to)209-217
Number of pages9
JournalJournal of Steroid Biochemistry and Molecular Biology
Volume171
DOIs
Publication statusPublished - 2017 Jul

Keywords

  • Breast cancer
  • DNA methylation
  • Estrogen receptor alpha
  • Ets-2
  • Hormone therapy resistance

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Endocrinology
  • Clinical Biochemistry
  • Cell Biology

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