QUANTITATION OF PROGESTERONE-RECEPTOR MESSENGER-RNA IN BREAST-CARCINOMA BY BRANCHED DNA ASSAY

Expression of progesterone receptor (PR) mRNA is indicative of a norma l gene regulation mechanism mediated by functional estrogen receptor ( ER). A simple assay which can reliably detect and quantitate PR mRNA l evels in a small amount of tissue will be of value for studying functi onal status of ER. We have developed a quantitative nucleic acid hybri dization assay for PR mRNA in breast carcinoma. The assay, which is ba sed on the branched DNA (bDNA) technology, is simple, highly specific, and reproducible, requires 20 mg of tissue, and correlates reasonably well (r = 0.86) with an established methodology. The assay has a dyna mic range of 3 x 10(3) - 6 x 10(7) copies of PR mRNA per well. PR mess age as high as 3.9 x 10(5) copies per well could be detected in normal breast tissues. Thus a sensitivity of 3 x 103 PR copies per well was sufficient for testing clinical samples. In the present studies, accur ate measurement of tissue weight enabled direct reporting of the PR mR NA values as the end point results. The bDNA assay provides a useful t ool for the detection and quantitation of PR mRNA in research and rout ine clinical laboratories.