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Updated: Apr 2, 2026

Profiling of Estrogen-regulated MicroRNAs in Breast Cancer Cells
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APOBEC3B-Mediated Cytidine Deamination Is Required for Estrogen Receptor Action in Breast Cancer

Manikandan Periyasamy1, Hetal Patel1, Chun-Fui Lai1

  • 1Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.

Cell Reports
|September 29, 2015
PubMed

Insights

APOBEC3B (A3B) deaminates DNA at estrogen receptor binding sites, promoting gene expression in ER+ breast cancer. This mechanism, involving DNA repair pathways, is linked to poorer patient survival.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cancer Research

Background:

  • Estrogen receptor alpha (ERα) is a critical driver in many breast cancers.
  • The precise mechanisms by which ERα regulates gene expression are complex and still under investigation.

Purpose of the Study:

  • To investigate the role of APOBEC3B (A3B) in the regulation of gene expression by ERα.
  • To elucidate the molecular mechanisms by which A3B influences ERα target gene activity.

Main Methods:

  • Assessing C-to-U deamination at ER binding regions.
  • Investigating DNA strand break generation via base excision repair (BER).
  • Analyzing repair by non-homologous end-joining (NHEJ) pathways.

Main Results:

  • APOBEC3B (A3B) causes C-to-U deamination at ER binding regions, facilitating ER-mediated gene regulation.
  • A3B-induced deamination triggers DNA strand breaks, repaired by BER and NHEJ.
  • Transient deamination by A3B promotes chromatin modification and remodelling at ER target gene regulatory regions, enhancing their expression.

Conclusions:

  • APOBEC3B is essential for ER-mediated gene regulation in ER+ breast cancer.
  • The A3B-driven mechanism involving DNA deamination and repair influences chromatin dynamics and gene expression.
  • A3B expression correlates with poor patient survival in ER+ breast cancer, highlighting its clinical relevance.

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