ABSTRACT
First-generation nonsteroidal androgen receptor (AR) antagonists, such as flutamide (2a) and bicalutamide (3), are effective for most prostate cancer patients, but resistance often appears after several years due to the mutation of AR. Second-generation AR antagonists are effective against some of these castration-resistant prostate cancers, but their structural variety is still limited. In this study, we designed and synthesized 4-methyl-7-(N-alkyl-arylcarboxamido)coumarins as AR antagonist candidates and evaluated their growth-inhibitory activity toward androgen-dependent SC-3 cells. Coumarinamides with a secondary amide bond did not show inhibitory activity, but their N-methylated derivatives exhibited AR-antagonistic activity. Especially, 19b and 31b were more potent than the lead compound 7b, which was comparable to hydroxyflutamide (2b). Conformational analysis showed that the inactive coumarinamides with a secondary amide bond have an extended structure with a trans-amide bond, while the active N-methylated coumarinamides have a folded structure with a cis-amide bond, in which the two aromatic rings are placed face-to-face. Docking study suggested that this folded structure is important for binding to AR. Selected coumarinamide derivatives showed AR-antagonistic activity toward LNCaP cells with T877A AR, and they had weak progesterone receptor (PR)-antagonistic activity. The folded coumarinamide structure appears to be a unique pharmacophore, different from those of conventional AR antagonists.
Subject(s)
Androgens/genetics , Prostatic Neoplasms, Castration-Resistant/drug therapy , Prostatic Neoplasms/drug therapy , Receptors, Androgen/genetics , Androgen Receptor Antagonists/chemistry , Androgen Receptor Antagonists/pharmacology , Androgens/metabolism , Cell Line, Tumor , Cell Proliferation/drug effects , Coumarins/chemistry , Coumarins/pharmacology , Flutamide/analogs & derivatives , Flutamide/chemistry , Flutamide/pharmacology , Humans , Male , Molecular Structure , Mutation , Nonsteroidal Anti-Androgens/chemistry , Nonsteroidal Anti-Androgens/pharmacology , Prostate-Specific Antigen/genetics , Prostatic Neoplasms/genetics , Prostatic Neoplasms/pathology , Prostatic Neoplasms, Castration-Resistant/genetics , Prostatic Neoplasms, Castration-Resistant/pathology , Receptors, Androgen/drug effectsABSTRACT
Progesterone is involved in multiple physiological processes, including female reproduction, via binding to the progesterone receptor (PR). We have developed 6-arylcoumarins such as 5 and 6 as non-steroidal PR antagonists with receptor-binding-dependent fluorescence. In this study, we investigated the structure-activity relationships and fluorescence properties of coumarin derivatives bearing a heterocyclic aromatic moiety. Among these derivatives, 7c (IC50: 34nM) and 10b (IC50: 24nM) showed more potent PR-antagonistic activity than lead compounds 5 (IC50: 500nM) and 6 (IC50: 65nM) in alkaline phosphatase (AP) assay. Compound 9b showed solvent-dependent fluorescence intensity, exhibiting strong fluorescence in the presence of PR LBD only in buffer solution. On the other hand, 10b showed a solvent-dependent shift of the fluorescence maximum wavelength in the presence of PR LBD. These results indicate that 6-arylcoumarin will be a useful scaffold for PR antagonists and fluorescent probes targeting PR.
