摘要 : 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 inhibito... 展开 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 wasdeveloped 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 experimentswere performed.Results: Transfected LNCaP prostate cancer cells were used as a source of 17β-HSD3 activity forthe 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 thesecells suggest a competitive action of RM-532-105 with the cofactor and a non-competitive actionwith 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 withprevious structure-activity relationships. 收起