A hybrid ligand method for androgen receptor measurement.
Existing techniques for androgen receptor (AR) assay are complicated by cross-reactivity of ligand binding affinities that can lead to incorrect estimation of receptor concentration. Two most frequently used ligands are [3H]dihydrotestosterone [( 3H]DHT) and [3H]methyltrienolone [( 3H]R1881), which in addition to binding to AR also bind to sex hormone binding globulin (SHBG; Kd = 1.5 nM) and progesterone receptors (PgR; Human Kd = 1 nM, rat Kd = 6 nM) respectively. Triamcinolone acetonide (TMA) is commonly used to block binding of [3H]R1881 to PgR, however at high concentrations TMA itself will bind AR (Kd = 7 microM). We have developed a hybrid ligand method for the measurement of AR in the presence of SHBG and PgR. This method used [3H]R1881 as the high specific activity labelled tracer and DHT as the unlabelled competitor of specific AR binding. Using this assay, 20% of human colorectal carcinomas were found to contain AR.
Stebbings
W S
WS
Department of Biochemistry, St Bartholomew's Hospital Medical College, London, England.
Anderson
E
E
Puddefoot
J R
JR
Farthing
M J
MJ
Vinson
G P
GP
D000818:Animals; D001667:Binding, Competitive; D003110:Colonic Neoplasms / Q000032:analysis; D003600:Cytosol / Q000378:metabolism; D013196:Dihydrotestosterone / Q000378:metabolism*; D004963:Estrenes / Q000378:metabolism*; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008297:Male; D015741:Metribolone; D009919:Orchiectomy; D011467:Prostate / Q000378:metabolism; D011470:Prostatic Hyperplasia / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011944:Receptors, Androgen / Q000032:analysis* / Q000378:metabolism; D012004:Rectal Neoplasms / Q000032:analysis; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D014222:Triamcinolone Acetonide / Q000378:metabolism*; D014316:Tritium; D014599:Uterus / Q000378:metabolism
D004963:Estrenes; D011944:Receptors, Androgen; D012738:Sex Hormone-Binding Globulin; D013196:Dihydrotestosterone; D014316:Tritium; D015741:Metribolone; D014222:Triamcinolone Acetonide