Stable expression of the human 5 alpha-reductase isoenzymes type I and type II in HEK293 cells to identify dual and selective inhibitors

A eucaryotic cell assay was established to identify novel, dual and selecti ve inhibitors of human 5 alpha -reductase. For this purpose the cDNAs encod ing 5 alpha -reductase type I and type II were inserted into a pRcCMV vecto r and expressed in human embryonic kidney (HEK293) cells. Single cell clone s with substantially high enzymatic activity were selected and established as permanent cell lines. K-M values were determined for both isozymes. The inhibitory potency of several steroidal and non-steroidal compounds synthes ized in our group, as well as finasteride and 4MA as controls, were tested by measuring the conversion of [H-3]androstenedione. Reaction products were quantified by a HPLC reversed phase technique. Using the new cell assays, selective as well as novel dual 5 alpha -reductase inhibitors with IC50 val ues between 1.0 and 2.5 muM were identified.