Observations on the presence of E domain variants of estrogen receptor-alpha in the breast tumors.
OBJECTIVE
Estrogen receptor-alpha (ER-alpha) 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-alpha 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 >or= 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.
Kumar
Vijay L
VL
Department of Pharmacology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India. kumarv198@hotmail.com
Kumar
Suresh
S
Srivastava
Anurag
A
Kumar
Vijay
V
D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D004797:Enzyme-Linked Immunosorbent Assay; D047628:Estrogen Receptor alpha / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005260:Female; D017353:Gene Deletion; D014644:Genetic Variation; D006801:Humans; D008207:Lymphatic Metastasis; D009362:Neoplasm Metastasis; D011379:Prognosis; D012326:RNA Splicing; D020133:Reverse Transcriptase Polymerase Chain Reaction
D047628:Estrogen Receptor alpha