Elevated expression of retinoic acid receptor-α (RARα) in estrogen- receptor-positive breast carcinomas as detected by immunohistochemistry

Qi Xia Han, Elizabeth A. Allegretto, Zhi Ming Shao, Timothy E. Kute, Jose Ordonez, Seena C. Aisner, Arun K. Rishi, Joseph A. Fontana

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Retinoids modulate gene activity, cell growth, and differentiation by binding to a series of nuclear receptors, i.e., retinoic acid receptors (RARs) or retinoid X receptors. Retinoic acid (RA) inhibition of estrogen receptor (ER)positive breast carcinoma seems to be mediated through RARα. Estrogens upregulate RARα in ER-positive breast carcinoma cell lines. In this study we examined RARα expression in the ER-positive MCF7 and ER negative MDA-MB-231 human breast carcinoma cell lines as well as in 10 ER- negative and 9 ER-positive infiltrating ductal breast carcinoma specimens using immunohistochemistry and quantitation by image cytometry. MCF7 cells expressed twofold higher levels of RARα protein than MDA-MB-231 cells. RARα expression, as detected by immunostaining and quantitated by image cytometry, was upregulated in these cells by estradiol. ER-positive breast carcinoma specimens also exhibited approximately twofold higher RARα levels than their ER-negative counterparts. Thus, RARα expression is significantly elevated in ER-positive breast tumors as assessed by detection and quantitation using immunohistochemical staining and image cytometry, respectively. Whether the decrease in RARα protein levels and loss of RA-mediated growth inhibition in ER negative tumor plays a role in the increased metastatic potential of ER- negative tumors remains to be determined.

Original languageEnglish (US)
Pages (from-to)42-48
Number of pages7
JournalDiagnostic Molecular Pathology
Issue number1
StatePublished - Feb 1997
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Pathology and Forensic Medicine
  • Molecular Biology
  • Cell Biology


  • Breast carcinoma
  • Estradiol
  • Immunohistochemistry
  • Retinoic acid receptor- α


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