Aryl hydrocarbon receptor induced intratumoral aromatase in breast cancer

Ryoko Saito, Yasuhiro Miki, Shuko Hata, Takanori Ishida, Takashi Suzuki, Noriaki Ohuchi, Hironobu Sasano

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Purpose: Aryl hydrocarbon receptor (AhR) inhibits estrogen receptor (ER) pathway, which may suppress estrogen-dependent cell proliferation. However, the correlation between AhR stimulation and intratumoral estrogen synthesis, especially through aromatase, has not been reported to date. In the present study, we examined this correlation in breast cancer cells. Methods: We examined AhR and aromatase immunoreactivity in 29 patients with invasive ductal carcinoma. We performed in vitro studies using three breast carcinoma cell lines, MCF-7, T47D, and MDA-MB-231. Results: AhR stimulation induced the mRNA expression of the aromatase gene in vitro in three breast carcinoma cell lines, and increased estrogen synthesis in MCF-7 cell line. Results of microarray analysis showed that AhR-induced aromatase expression was associated with BRCA1 induction. Analysis of patients with breast cancer showed a significant positive correlation between intratumoral AhR and aromatase status. We also compared the effects of AhR stimulation on the induction of intratumoral estrogen synthesis and inhibition of the ER signaling pathway, because AhR exerts contradictory effects on estrogen action in breast carcinoma cells. AhR-induced aromatase expression persisted for a significantly longer duration than AhR-induced ER pathway inhibition. Moreover, breast carcinoma cells treated with an AhR agonist tended to show earlier cell proliferation after removing the agonist than cells not treated with the AhR agonist. Conclusion: The results of the present study suggest that AhR stimulates estrogen-dependent progression of breast carcinoma by inducing aromatase expression under some conditions. These results provide new insights on the possible roles of environmental toxins in breast cancer development.

Original languageEnglish
Pages (from-to)399-407
Number of pages9
JournalBreast Cancer Research and Treatment
Issue number3
Publication statusPublished - 2017 Feb 1


  • Aromatase
  • Aryl hydrocarbon receptor
  • Breast cancer
  • Estrogen receptor pathway

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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