Sensitive Detection of Estrogen Receptor RNA by Polymerase Chain Reaction Assay

We developed a simplified polymerase chain reaction (PCR) technique sensitive enough to detect estrogen receptor (ER) mRNA in breast tumor specimens from 1 microgram of total RNA. We simultaneously amplified a control gene such as beta-actin as a baseline to semiquantitate ER expression. In a preliminary test of this method on a small series of breast tumors, ER message was found as expected in a number of tumors found to be ER positive by ligand binding assay, but also ER negative in one tumor assayed. The ER in this last tumor contained a single base change in the hormone binding region, compared with the MCF-7 breast tumor cell line ER. Therefore, this PCR technique may be useful in the detection and cloning of rare ER transcripts from breast tumor biopsy specimens.