Title:Insight into the Mechanism of 17β-Hydroxysteroid Dehydrogenase Type 3 Inhibition by the Androsterone Derivative RM-532-105
Volume: 16
Issue: 3
Author(s): Preyesh Stephen, Jenny Roy, René Maltais and Donald Poirier*
Affiliation:
- Endocrinology and Nephrology Unit, CHU de Quebec - Research Center, Quebec, QC,Canada
Keywords:
17beta-HSD3, androgen, docking, enzyme inhibitor, steroid, non-steroid.
Abstract:
Background: The last step in the production of androgen testosterone from 4-androstene-
3,17-dione (4-dione) in testis involves the 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3).
Blocking this microsomal enzyme with an inhibitor would lower the level of testosterone and, consequently,
could be an approach for the treatment of androgen-dependent diseases. RM-532-105 was
developed as a steroidal inhibitor of 17β-HSD3, but its mechanism of action is not yet known.
Objective: To identify potential binding sites of the 17β-HSD3 substrate 4-dione, cofactor NADPH,
as well as inhibitor RM-532-105.
Methods: Since there is no crystal structure of 17β-HSD3 available, complexed or not with a ligand,
a homology model was prepared followed by molecular docking, and enzymatic assay experiments
were performed.
Results: Transfected LNCaP prostate cancer cells were used as a source of 17β-HSD3 activity for the
transformation of 4-dione into testosterone in the presence of varying concentrations of a substrate, a
cofactor or an inhibitor. Molecular modeling experiments and enzymatic assays with these cells suggest
a competitive action of RM-532-105 with the cofactor and a non-competitive action with the
substrate 4-dione.
Conclusion: These results allow the selection of one inhibitor orientation in the enzyme binding site,
from the two possibilities predicted by the docking experiments, and appear to be in agreement with
previous structure-activity relationships.
