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J Clin Pathol. 2011 Jan;64(1):54-7. doi: 10.1136/jcp.2010.082776. Epub 2010 Nov 2.

ER-α36, a novel isoform of ER-α66, is commonly over-expressed in apocrine and adenoid cystic carcinomas of the breast.

Author information

  • 1Department of Pathology, Creighton University Medical Center, Omaha, Nebraska, USA. semir.vranic@gmail.com

Abstract

BACKGROUND:

ER-α36 is a novel 36 kDa isoform of the full-length oestrogen receptor alpha (ER-α66). ER-α36 primarily localises to the cytoplasm and the plasma membrane, and responds to membrane-initiated oestrogen and antioestrogen signalling pathways.

AIM:

To examine the expression of ER-α36 in apocrine and adenoid cystic carcinoma of the breast, both of which are consistently ER-α66 negative and currently lack effective targeted therapeutic options.

METHODS:

19 pure apocrine carcinomas (17 invasive and two in-situ carcinomas) and 11 adenoid cystic carcinomas of the breast were evaluated for ER-α36 expression, along with expressions of ER-α66, progesterone receptor (PR) and androgen receptor (AR) using immunohistochemical methods.

RESULTS:

All pure apocrine carcinomas showed a characteristic steroid receptor expression profile (ER-α66 and PR negative, AR strongly positive). ER-α36 expression was detected in 18/19 pure apocrine carcinomas (94.7%, 95% CI 75.1 to 98.7) in predominantly membranous and cytoplasmic distribution. When positive, pure apocrine carcinomas uniformly (100% of cells) expressed ER-α36. All adenoid cystic carcinomas were uniformly negative for all three classic steroid receptors, but ER-α36 was detected in 8/11 cases (72.7%, 95% CI 42.8 to 90) with the similar sub-cellular pattern of expression as in the pure apocrine carcinomas. When positive, adenoid cystic carcinomas expressed ER-α36 in the majority of cells (average 76%).

CONCLUSION:

ER-α36, a novel isoform of ER-α66, is frequently over-expressed in apocrine and adenoid cystic carcinomas of the breast. These results indicate a potential for a novel targeted treatment in these cancers.

PMID:
21045236
[PubMed - indexed for MEDLINE]
PMCID:
PMC3380072
Free PMC Article

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