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Observations on the presence of E domain variants of estrogen receptor‐α in the breast tumors
Author(s) -
Kumar Vijay L.,
Kumar Suresh,
Srivastava Anurag,
Kumar Vijay
Publication year - 2006
Publication title -
journal of surgical oncology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.201
H-Index - 111
eISSN - 1096-9098
pISSN - 0022-4790
DOI - 10.1002/jso.20588
Subject(s) - medicine , estrogen receptor , estrogen , domain (mathematical analysis) , breast cancer , cancer research , estrogen receptor beta , oncology , cancer , mathematical analysis , mathematics
Background and Objectives Estrogen receptor‐α (ER‐α) that exists as multiple splice variants, has been widely used as a prognostic marker in the management of breast cancer. Here we have analyzed the hormone binding E domain splice variants of ER‐α in the breast tumors with reference to the immunoreactive receptor. Methods Thirty breast cancer patients undergoing surgery at the All India Institute of Medical Sciences, New Delhi, were analyzed for the splice variants of E domain by RT‐PCR. The ER level was determined by ELISA and the samples were considered positive if the receptor levels were ≥ 15 fmol/mg protein. Results Our results show that exon 4 and 5 deletions were prevalent in both ER‐positive and ER‐negative categories. While most ER‐positive cases expressed wild‐type (wt) exon 6 + 7, nearly 40% of ER‐negative cases showed deletion of exon 6 + 7. Therefore, deletion of exon 6 + 7 or masking of epitopes could lead to underestimation of ER by ELISA. All the metastasis and recurrence cases had undetectable levels of ER. A significant number of node‐positive cases expressed immunoreactive ER and wt exon 6 + 7 (r = 0.509, P < 0.37). Conclusions Estimation of ER levels combined with composite analysis of ER variants may be a better prognostic marker for breast cancer. J. Surg. Oncol. 2006;94:332–337. © 2006 Wiley‐Liss, Inc