Optimization and prevalidation of the in vitro AR CALUX method to test androgenic and antiandrogenic activity of compounds.

To date there are no validated methods available to test androgenicity or antiandrogenicity in vitro. A problem with testing androgenicity using reporter genes is the possibility by other steroid receptors than androgen receptors to activate the same reporter gene, thereby lowering selectivity. To avoid this we have established a robust and very selective method, the AR CALUX reporter gene assay, to test androgenic and antiandrogenic activity of compounds in vitro. This assay uses a human U2-OS cell line stably transfected with the human androgen receptor and an androgen receptor responsive reporter gene. We optimized protocols to be used in combination with AR CALUX cells and carried out an in house prevalidation. In addition we successfully transferred this assay to another laboratory, leading to comparable test results with a panel of androgen receptor agonists and antagonists. The assay was able to readily rank a range of chemicals on the basis of their EC50 values. The CALUX assay was found to be selective for androgens and seemed not influenced by signaling through other steroid receptors.