ORG-2058 as a ligand in the assay of progesterone receptor in breast cancer

• Published in: Steroids Vol. 48; no. 5; pp. 419 - 426
• Main Authors: Sharoni, Yoav, Feldman, Bianca, Karny, Noga, Levy, Joseph
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.11.1986; Elsevier Science
• Subjects: Animals; Biological and medical sciences; Breast Neoplasms - metabolism; Cytosol - metabolism; Female; Genital system. Mammary gland; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Mammary Neoplasms, Experimental - metabolism; Medical sciences; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Pregnenediones; Promegestone; Rats; Receptors, Progesterone - analysis; Uterus - metabolism; Assay; Human; Vertebrata; Mammalia; Rat; Ligand; Rodentia; Tumor; Mammary gland; Progesterone; Sex steroid hormone; Hormonal receptor
• ISSN: 0039-128X; 1878-5867
• DOI: 10.1016/0039-128X(86)90028-0

Tritiated [(16α-ethyl-21-hydroxy-19-nor-pregn-4-ene-3, 20-dione)-6,7- 3H] (ORG-2058) and 17,21-dimethyl-19-nor-pregna-4,9-diene-3,20-dione (R5020) were compared as ligands in the assay of progesterone receptor in human of and rat breast tumors. We found that ORG-2058 is a better ligand because its low nonspecific binding. Most of the nonspecific binding of the other ligand R5020, is to proteins which bind corticosteroids. In cancerous tissue ORG-2058 binds to progesterone receptor linearly in a range of protein concentrations which are normally used in the receptor assay. On the other hand, R5020 exhibits binding linearity over a narrower protein concentration in many tumor biopsies, which may cause severe limitation in the assay procedure or frequent underestimation of receptor content.