Garola R E, McGuire W L
Cancer Res. 1977 Sep;37(9):3333-7.
We have validated a hydroxylapatite assay for measuring estrogen receptor in extracts from breast tumor nuclei. By adsorption of receptor of hydroxylapatite prior to addition of radioactive ligand and warming, receptor degradation can be avoided. Total binding sites are measured at 30 degrees by exchange, and receptor sites unoccupied by steroid are measured at 4 degrees. A single saturating dose of 5 nM tritiated estradiol (with or without a 100-fold excess of nonradioactive diethylstilbestrol to estimate nonspecific binding) yields results similar to a six-dose Scatchard plot. Following in vivo injection of estradiol into rats bearing mammary tumors, receptor translocation in the tumors can be accurately quantitated with this assay. Applying the assay to human breast cancer, we find that tumor biopsies may contain cytoplasmic receptor alone or may also have appreciable nuclear receptor. The latter may be bound to estradiol or may be found in "free" form. The finding of free receptor in the nuclei in certain cases raises the possibility that unoccupied receptor might be able to stimulate cell replication in these cases, even in the absence of estrogen.
我们已经验证了一种用于测量乳腺肿瘤细胞核提取物中雌激素受体的羟基磷灰石测定法。通过在添加放射性配体之前将受体吸附到羟基磷灰石上并进行温育，可以避免受体降解。通过交换在30摄氏度下测量总结合位点，在4摄氏度下测量未被类固醇占据的受体位点。5 nM的单一饱和剂量的氚化雌二醇（有或没有100倍过量的非放射性己烯雌酚以估计非特异性结合）产生的结果类似于六剂量的Scatchard图。在给患有乳腺肿瘤的大鼠体内注射雌二醇后，用该测定法可以准确地定量肿瘤中的受体转位。将该测定法应用于人类乳腺癌，我们发现肿瘤活检可能仅含有细胞质受体，也可能含有相当数量的核受体。后者可能与雌二醇结合，也可能以“游离”形式存在。在某些情况下在细胞核中发现游离受体增加了这样一种可能性，即在这些情况下，即使没有雌激素，未被占据的受体也可能能够刺激细胞复制。
