Rational design of orally-active, pyrrolidine-based progesterone receptor partial agonists (original) (raw)
Related papers
Improving the developability profile of pyrrolidine progesterone receptor partial agonists
Bioorganic & Medicinal Chemistry Letters, 2010
The previously reported pyrrolidine class of progesterone receptor partial agonists demonstrated excellent potency but suffered from serious liabilities including hERG blockade and high volume of distribution in the rat. The basic pyrrolidine amine was intentionally converted to a sulfonamide, carbamate, or amide to address these liabilities. The evaluation of the degree of partial agonism for these non-basic pyrrolidine derivatives and demonstration of their efficacy in an in vivo model of endometriosis is disclosed herein.
Characterization of a new class of selective nonsteroidal progesterone receptor agonists
Steroids, 2004
The identification of a new series of selective nonsteroidal progesterone receptor (PR) agonists is reported. Using a high-throughput screening assay based on the measurement of transactivation of a mouse mammary tumor virus promoter-driven luciferase reporter (MMTV-Luc) in human breast cancer T47D cells, a benzimidazole-2-thione analog was identified. Compound 1 showed an apparent EC50 of 53 nM and efficacy of 93% with respect to progesterone. It binds to PR with high affinity (Ki nM), but had no or very low affinity for other steroid hormone receptors. Structure-activity relationship studies of a series of benzimidazole-2-thione analogs revealed critical positions for high PR binding affinity and transactivation potency as well as receptor selectivity, as exemplified by 25. Compound 25 binds to human PR with high affinity (Ki nM) and had at least > 1000-fold selectivity for PR versus other steroid receptors. Molecular modeling studies suggested that these agonists overlap favorably with progesterone in the ligand-binding domain of PR. In T47D cells, compound 25 acted as a full agonist in the MMTV-Luc reporter assay, as well as in the induction of endogenous alkaline phosphatase activity with apparent EC50 values of 4 and 9 nM, respectively. In the immature rat model, compound 25 provided a significant suppression of estrogen-induced endometrium hypertrophy as measured by luminal epithelial height. In contrast, compound 25 was inactive in the luteinizing hormone release assay in young ovariectomized rats. These benzimidazole-2-thione analogs constitute a new series of nonsteroidal PR agonists with an excellent steroid receptor selectivity profile. The differential activities observed in the in vivo progestogenic assays in rat models suggest that these analogs can act as selective PR modulators.
A New Strategy for Selective Targeting of Progesterone Receptor With Passive Antagonists
Molecular Endocrinology, 2013
Currently available progesterone (P4) receptor (PR) antagonists, such as mifepristone (RU486), lack specificity and display partial agonist properties, leading to potential drawbacks in their clinical use. Recent x-ray crystallographic studies have identified key contacts involved in the binding of agonists and antagonists with PR opening the way for a new rational strategy for inactivating PR. We report here the synthesis and characterization of a novel class of PR antagonists (APRn) designed from such studies. The lead molecule, the homosteroid APR19, displays in vivo endometrial anti-P4 activity. APR19 inhibits P4-induced PR recruitment and transactivation from synthetic and endogenous gene promoters. Importantly, it exhibits high PR selectivity with respect to other steroid hormone receptors and is devoid of any partial agonist activity on PR target gene transcription. Two-hybrid and immunostaining experiments reveal that APR19-bound PR is unable to interact with either steroid receptor coactivators 1 and 2 (SRC1 and SCR2) or nuclear receptor corepressor (NcoR) and silencing mediator of retinoid acid and thyroid hormone receptor (SMRT), in contrast to RU486-PR complexes. APR19 also inhibits agonist-induced phosphorylation of serine 294 regulating PR transcriptional activity and turnover kinetics. In silico docking studies based on the crystal structure of the PR ligand-binding domain show that, in contrast to P4, APR19 does not establish stabilizing hydrogen bonds with the ligandbinding cavity, resulting in an unstable ligand-receptor complex. Altogether, these properties highly distinguish APR19 from RU486 and likely its derivatives, suggesting that it belongs to a new class of pure antiprogestins that inactivate PR by a passive mechanism. These specific PR antagonists open new perspectives for long-term hormonal therapy.
Journal of Biological Chemistry, 2011
The progesterone receptor is able to bind to a large number and variety of ligands that elicit a broad range of transcriptional responses ranging from full agonism to full antagonism and numerous mixed profiles inbetween. We describe here two new progesterone receptor ligand binding domain x-ray structures bound to compounds from a structurally related but functionally divergent series, which show different binding modes corresponding to their agonistic or antagonistic nature. In addition, we present a third progesterone receptor ligand binding domain dimer bound to an agonist in monomer A and an antagonist in monomer B, which display binding modes in agreement with the earlier observation that agonists and antagonists from this series adopt different binding modes.
Bioorganic & Medicinal Chemistry Letters, 2008
We have developed a new class of progesterone receptor agonists having a tetracyclic dibenzo-oxazepine structure 1. In this paper, the synthesis and structure-activity relationships of this new class are described. This work led to the identification of potent progesterone agonists up to 1 nM activity. Substitution at positions 6, 7 and 1 has proven to be crucial for activity, indicating that probably these positions are involved in important interactions with the receptor.
Bioorganic & Medicinal Chemistry, 2011
The biological activity of two seven-membered A-ring (A-homo) analogues of progesterone was evaluated by transactivation assays in Cos-1 cells and by determination of Bcl-x L expression levels in T47D cells. The results show that both compounds act as selective progesterone receptor (PR) agonists but lack mineralocorticoid receptor (MR) activity. Molecular modelling using semiempirical AM1 and ab initio HF/ 6-31G ⁄⁄ calculations, showed that the A-ring of the A-homo steroids may adopt five different conformations, although only three correspond to low energy conformers. The low energy conformers of each analogue were introduced into the ligand binding pocket of the PR ligand binding domain (LBD) obtained from the PR LBD-progesterone crystal structure. The steroid binding mode was then analyzed using 10 ns of molecular dynamics (MD) simulation. The PR LBD-progesterone complex was also simulated as a control system. The MD results showed that both A-homo steroids have one conformer that may be properly recognized by the PR, in agreement with the observed progestagen activity. Moreover, the simulation revealed the importance of a water molecule in the formation of a hydrogen bonding network among specific receptor residues and the steroid A-ring carbonyl.