A simple and sensitive high-throughput assay for steroid agonists and antagonists

Area of Science:

• Biochemistry
• Molecular Biology
• Endocrinology

Background:

• Steroid compounds regulate numerous biological processes.
• Accurate and sensitive assays are crucial for analyzing steroid activity.
• Existing methods may lack the sensitivity required for detecting low-level steroid effects.

Purpose of the Study:

• To develop a novel, highly sensitive tissue culture-based assay for evaluating the biological activity of steroids.
• To establish stable human cell lines for efficient screening of steroid agonists and antagonists.
• To enable the detection of low-level agonist activity in steroid antagonists.

Main Methods:

• Development of a synthetic steroid-inducible promoter (GRE5) controlling chloramphenicol acetyltransferase (CAT) gene expression.
• Insertion of the GRE5-CAT cassette into an Epstein-Barr virus (EBV) episomal vector.
• Generation of stably transfected human cell lines (HeLa and T47D) for autonomous replication of the vector.
• Utilizing a colorimetric CAT assay for direct screening of compounds in microtiter wells.

Main Results:

• The GRE5 promoter demonstrated over 100-fold induction by specific steroids (dexamethasone, progesterone, dihydrotestosterone) in respective cell lines.
• Basal expression of CAT activity was strictly steroid-dependent, allowing detection of very low induction levels.
• The developed cell lines effectively screened for steroid agonist and antagonist activities.

Conclusions:

• The established cell lines provide a sensitive and efficient platform for screening and analyzing a large number of steroid compounds.
• This assay system facilitates the identification of both steroid agonists and antagonists.
• The method is applicable to screening natural and synthetic steroidal compounds for biological activity.