A simple method for the determination of oestrogen receptor concentrations in breast tumours and other tissues

Abstract

A simple method for the determination of oestrogen receptor activity in breast tumours and other tissues is described. By competition between radioactive and non-radioactive oestradiol-17β for binding to a tissue extract prepared with centrifugation at low speed, the presence or absence of receptors is decided from the unmanipulated data. The concentration of receptors ( P o) and dissociation constant of binding ( K d) are calculated by Scatchard analysis. In two relatively homogeneous tissues, assay precision was of the order of 16% for receptor concentration and 21–33% for the dissociation constant of binding: in heterogeneous breast tumors, much poorer precision can be expected. Sensitivity determined empirically is approximately 0.1 fmol/mg tissue. The method has been applied to the determination of receptor concentrations in human breast cancers, benign breast tumours, non-malignant breast, gynaecomastic breast, and in various tissues of the rat. Receptor activity was detected in 70% of the human breast cancers examined, and in lower amounts, in 21% of the benign human breast tissues. Activity was also detected in rat uterus and mammary gland, and in low amounts in 82% of the rat mammary tumours analysed. Dissociation constant of binding was generally of the order of 0.5 × 10 −10 M. The advantages of the method are discussed.