Microassays for androgen and progesterone receptor quantitation as compared with standard saturation analyses in human prostatic tissues.

Simultaneous measurement of androgen and progesterone receptor content in cytosol and salt extractable nuclear subcompartments of benign hyperplastic prostatic tissue was carried out with various microassay techniques and compared to the results from analyses on bulky tissue from the same tissue specimens. The microassays were carried out as modified saturation analyses or as single concentration assays at various degrees of dilution with tris-EDTA-glycerol (TEG) buffer. Tissue samples for the standard assay weighed between 1.76 and 3.22 g, whereas the microassay samples weighted between 0.14 and 0.47 g. When considering the results of the standard assay as the "true" value, the microassays on the same tissue samples tended to underestimate both the androgen and progesterone receptor contents. Data from the microassays showed a wide variation of the androgen and progesterone receptor content in cytosol and nuclei. With the standard assay technique no detectable amount of progesterone receptor was found in the nuclei, whereas the microassays often indicated false-positive progesterone receptor content in this subcompartment. Therefore, the measurements of steroid receptors using biochemical microassays in prostatic tissue are unreliable and not suitable for clinical use, at least with the techniques available today. Reports in the literature based on such assays should therefore be interpreted with great caution.