Normal and stable transfected cancer cell lines: tools for a screening of progestogenic, antiprogestogenic and antiglucocorticoid substances

Abstract

Synthetic ligands for steroid receptors represent important drugs in the control of fertility and in the therapy of a large variety of endocrinological diseases. In the present study we describe the establishment of different biochemical and molecular biological screening methods. We developed a microtiter plate assay for the induction of the de novo synthesis of alkaline phosphatase in T47D cells as a suitable and fast system for the measurement of actions of progestogenic and antiprogestogenic compounds. We compared several progestogenic activities with relative molar binding affinities (RBA) to the progesterone receptor. The ED50 values for the induction of alkaline phosphatase are in good accordance with RBA to the progesterone receptor. Furthermore, glucocorticoid and antiglucocorticoid effects were measured in the stable transfected breast cancer cell line ZR75/-763AGP-CAT. The construct AGP-CAT contains the glucocorticoid responsible element of the rat alpha-1-acid glycoprotein (AGP) gene with the bacterial chloramphenicol acetyltransferase (CAT) gene. The rat hepatoma Reuber cell line H4-II-E with the tyrosine aminotransferase gene is a further suitable marker of glucocorticoid action and was used as a second model for glucocorticoid activity. Thus, we demonstrated in three cell systems the antiprogestogenic and antiglucocorticoid activities of the model compound mifepristone.