MACROMOLECULAR BINDING OF GLUCOCORTICOIDS IN HUMAN MAMMARY-CARCINOMA

  • 1 January 1977
    • journal article
    • research article
    • Vol. 37  (3) , 640-645
Abstract
The presence of glucocorticoid receptors was examined in 100 primary and 22 metastatic human breast cancer lesions. Aliquots of cytosol were incubated in vitro with 3H-cortisol and dexamethasone with and without competing steroids. Two types of glucocorticoid receptors were detected. One is similar to transcortin. It sediments at 4 S in the ultracentrifuge, has a dissociation constant in the same range (10-8 M) and does not bind fluorinated corticosteroids. While every tumor showed cortisol binding, very high activity (> 1000 fmol/g tissue) was detected in 38% of primaries and in 59% of metastases. Plasma transcortin could be excluded as the source of binding activity. The other receptor binds natural and fluorinated corticosteroids, has a higher affinity (Kd 10-9 M), and sediments at 8 S. It was present in 23% of tumors and its quantity (26-995 fmol/g) was less than that of cortisol binder (50-6000 fmol/g). While there was no correlation between the 2 glucocorticoid receptors, 80% of dexamethasone receptor positive cases also had estrogen receptor. The results indicate that a significant proportion of these tumors could be subject to glucocorticoid influence.

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