Cytosol and nuclear estradiol receptors in normal and cancerous breast tissue of women

Specific estradiol receptors were quantitatively determined in the cytosol and nuclear fractions of twelve cancerous and six normal breast tissues of women. The number of cytosol receptors was observed to be in the range of 10-800 f moles/100 μg. nuclear DNA in the cancerous tissues and 26-500 f moles in the normal tissues, while the number of nuclear receptors was observed to be from 10-107 f moles/100 μg. nuclear DNA in the cancerous tissues and from 13-104 f moles in the normal tissues. Thus the number of nuclear receptors was significantly less compared with cytosol receptors. Sucrose gradient analysis demonstrated that cytosols from 50% of the cancerous tissues had identical sedimentation pattern to the cytosols from normal tissues, wherein two peaks in the regions of 3-5 S and 8-9 S were observed. The cytosols from other cancerous tissues demonstrated a variable and abnormal pattern. The dissociation constant (Kd) of the estradiol receptors, analysed from the scatchard plot, was observed to be higher in the cytosols of cancerous tissues (mean Kd 0.74 nM) compared with cytosols from normal tissues (mean Kd 0.49 nM). These findings have been discussed in relation to clinical parameters of the patients.