Synthesis and biological activity of a novel, highly potent progesterone receptor antagonist

Antiprogestins for breast cancer treatment: We are almost ready

The development of antiprogestins was initially a gynecological purpose. However, since mifepristone was developed, its application for breast cancer treatment was immediately proposed. Later, new compounds with lower antiglucocorticoid and antiandrogenic effects were developed to be applied to different pathologies, including breast cancer. We describe herein the studies performed in the breast cancer field with special focus on those reported in recent years, ranging from preclinical biological models to those carried out in patients. We highlight the potential use of antiprogestins in breast cancer prevention in women with BRCA1 mutations, and their use for breast cancer treatment, emphasizing the need to elucidate which patients will respond. In this sense, the PR isoform ratio has emerged as a possible tool to predict antiprogestin responsiveness. The effects of combined treatments of antiprogestins together with other drugs currently used in the clinic, such as tamoxifen, CDK4/CDK6 inhibitors or pembrolizumab in preclinical models is discussed since it is in this scenario that antiprogestins will be probably introduced. Finally, we explain how transcriptomic or proteomic studies, that were carried out in different luminal breast cancer models and in breast cancer samples that responded or were predicted to respond to the antiprogestin therapy, show a decrease in proliferative pathways. Deregulated pathways intrinsic of each model are discussed, as well as how these analyses may contribute to a better understanding of the mechanisms involved.

Cortisol/glucocorticoid receptor: a critical mediator of the ovulatory process and luteinization in human periovulatory follicles

STUDY QUESTION

Do cortisol/glucocorticoid receptors play an active role in the human ovary during ovulation and early luteinization?

SUMMARY ANSWER

The ovulatory hCG stimulation-induced glucocorticoid receptor signaling plays a crucial role in regulating steroidogenesis and ovulatory cascade in human periovulatory follicles.

WHAT IS KNOWN ALREADY

Previous studies reported an increase in cortisol levels in the human follicular fluid after the LH surge or ovulatory hCG administration. However, little is known about the role of cortisol/glucocorticoid receptors in the ovulatory process and luteinization in humans.

STUDY DESIGN, SIZE, DURATION

This study was an experimental prospective clinical and laboratory-based study. An in vivo experimental study was accomplished utilizing the dominant ovarian follicles from 38 premenopausal women undergoing laparoscopic sterilization. An in vitro experimental study was completed using the primary human granulosa/lutein cells (hGLC) from 26 premenopausal women undergoing IVF.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This study was conducted in a private fertility clinic and academic medical centers. Dominant ovarian follicles were collected before the LH surge and at defined times after hCG administration from women undergoing laparoscopic sterilization. Primary hGLC were collected from women undergoing IVF. hGLC were treated without or with hCG in the absence or presence of RU486 (20 µM; dual antagonist for progesterone receptor and glucocorticoid receptor) or CORT125281 (50 µM; selective glucocorticoid receptor antagonist) for 12 or 36 h. The expression of genes involved in glucocorticoid receptor signaling, steroidogenesis, and ovulatory cascade was studied with RT-quantitative PCR and western blotting. The production of cortisol, corticosterone, and progesterone was assessed by hormone assay kits.

MAIN RESULTS AND THE ROLE OF CHANCE

hCG administration upregulated the expression of hydroxysteroid 11-beta dehydrogenase 1 (HSD11B1), nuclear receptor subfamily 3 group C member 1 (NR3C1), FKBP prolyl isomerase 5 (FKBP5), and FKBP prolyl isomerase 4 (FKBP4) in human ovulatory follicles and in hGLC (P < 0.05). RU486 and CORT125281 reduced hCG-induced increases in progesterone and cortisol production in hGLC. The expression of genes involved in glucocorticoid receptor signaling, steroidogenesis, and the key ovulatory process was reduced by RU486 and/or CORT125281 in hGLC.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

The role of cortisol/glucocorticoid receptors demonstrated using the hGLC model may not fully reflect their physiological roles in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

Successful ovulation and luteinization are essential for female fertility. Women with dysregulated cortisol levels often suffer from anovulatory infertility. Deciphering the functional role of glucocorticoid receptor signaling in human periovulatory follicles enhances our knowledge of basic ovarian physiology and may provide therapeutic insights into treating infertility in women.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by P01HD71875 (to M.J., T.E.C., and M.B.) and R01HD096077 (to M.J.) from the Foundation for the National Institutes of Health and the BTPSRF of the University of Kentucky Markey Cancer Center (P30CA177558). The authors report no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

A Novel Dialkylamino-Functionalized Chalcone, DML6, Inhibits Cervical Cancer Cell Proliferation, In Vitro, via Induction of Oxidative Stress, Intrinsic Apoptosis and Mitotic Catastrophe

In this study, we designed, synthesized and evaluated, in vitro, novel chalcone analogs containing dialkylamino pharmacophores in the cervical cancer cell line, OV2008. The compound, DML6 was selective and significantly decreased the proliferation of OV2008 and HeLa cells in sub-micromolar concentrations, compared to prostate, lung, colon, breast or human embryonic kidney cell line (HEK293). DML6, at 5 μM, arrested the OV2008 cells in the G2 phase. Furthermore, DML6, at 5 μM, increased the levels of reactive oxygen species and induced a collapse in the mitochondrial membrane potential, compared to OV2008 cells incubated with a vehicle. DML6, at 5 μM, induced intrinsic apoptosis by significantly (1) increasing the levels of the pro-apoptotic proteins, Bak and Bax, and (2) decreasing the levels of l the anti-apoptotic protein, Bcl-2, compared to cell incubated with a vehicle. Furthermore, DML6, at 5 and 20 μM, induced the cleavage of caspase-9, followed by subsequent cleavage of the executioner caspases, caspase-3 and caspase-7, which produced OV2008 cell death. Overall, our data suggest that DML6 is an apoptosis-inducing compound that should undergo further evaluation as a potential treatment for cervical cancer.

Structure-based virtual screening of perfluoroalkyl and polyfluoroalkyl substances (PFASs) as endocrine disruptors of androgen receptor activity using molecular docking and machine learning

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) pose a substantial threat as endocrine disruptors, and thus early identification of those that may interact with steroid hormone receptors, such as the androgen receptor (AR), is critical. In this study we screened 5,206 PFASs from the CompTox database against the different binding sites on the AR using both molecular docking and machine learning techniques. We developed support vector machine models trained on Tox21 data to classify the active and inactive PFASs for AR using different chemical fingerprints as features. The maximum accuracy was 95.01% and Matthew's correlation coefficient (MCC) was 0.76 respectively, based on MACCS fingerprints (MACCSFP). The combination of docking-based screening and machine learning models identified 29 PFASs that have strong potential for activity against the AR and should be considered priority chemicals for biological toxicity testing.

Ligand Binding Induces Agonistic-Like Conformational Adaptations in Helix 12 of Progesterone Receptor Ligand Binding Domain

Progesterone receptor (PR) is a member of the nuclear receptor (NR) superfamily and plays a vital role in the female reproductive system. The malfunction of it would lead to several types of cancers. The understanding of conformational changes in its ligand binding domain (LBD) is valuable for both biological function studies and therapeutically intervenes. A key unsolved question is how the binding of a ligand (agonist, antagonist, or a selective modulator) induces conformational changes of PR LBD, especially its helix 12. We applied molecular dynamics (MD) simulations to explore the conformational adaptations of PR LBD with or without a ligand or the co-repressor peptides binding. From the simulations, both the agonist progesterone (P4) and the selective PR modulator (SPRM) asoprisnil induces agonistic-like helix 12 conformations (the "closed" states) in PR LBD and the complex of LBD-SPRM is less stable, comparing to the agonist-liganded PR LBD. The results, therefore, explain the partial agonism of the SPRM, which could induce weak agonistic effects in PR. We also found that co-repressor peptides could be stably associated with the LBD and stabilize the LBD in a "semi-open" state for helix 12. These findings would enhance our understanding of PR structural and functional relationships and would also be useful for future structure and knowledge-based drug discovery.

Discovery of Vilaprisan (BAY 1002670): A Highly Potent and Selective Progesterone Receptor Modulator Optimized for Gynecologic Therapies

Progesterone plays an important role in the female reproductive system. However, there is also evidence that gynecologic disorders/diseases such as uterine fibroids and endometriosis are progesterone-dependent. Steroidal and non-steroidal selective progesterone receptor modulators (SPRMs) have shown potential for the treatment of such diseases. Steroidal SPRMs, including mifepristone and ulipristal acetate, have proven effective in clinical trials. However, several steroidal SPRMs containing a dimethylamino substituent have been associated with elevated liver enzymes in patients. An earlier drug discovery program identified lonaprisan as a highly selective SPRM that did not show drug-related change in liver enzyme activity. Building on data obtained from that work, here we describe the research program that culminated in the discovery of a novel steroidal SPRM, vilaprisan, which combines an extremely high potency with very favorable drug metabolism and pharmacokinetic properties. Vilaprisan has entered clinical development and is currently undergoing phase 3 clinical trials.

Potential contribution of progesterone receptors to the development of sexual behavior in male and female mice

We previously showed that estradiol can have both defeminizing and feminizing effects on the developing mouse brain. Pre- and early postnatal estradiol defeminized the ability to show lordosis in adulthood, whereas prepubertal estradiol feminized this ability. Furthermore, we found that estradiol upregulates progesterone receptors (PR) during development, inducing both a male-and female-typical pattern of PR expression in the mouse hypothalamus. In the present study, we took advantage of a newly developed PR antagonist (ZK 137316) to determine whether PR contributes to either male- or female-typical sexual differentiation. Thus groups of male and female C57Bl/6j mice were treated with ZK 137316 or OIL as control: males were treated neonatally (P0-P10), during the critical period for male sexual differentiation, and females were treated prepubertally (P15-P25), during the critical period for female sexual differentiation. In adulthood, mice were tested for sexual behavior. In males, some minor effects of neonatal ZK treatment on sexual behavior were observed: latencies to the first mount, intromission and ejaculation were decreased in neonatally ZK treated males; however, this effect disappeared by the second mating test. By contrast, female mice treated with ZK during the prepubertal period showed significantly less lordosis than OIL-treated females. Mate preferences were not affected in either males or females treated with ZK during development. Taken together, these results suggest a role for PR and thus perhaps progesterone in the development of lordosis behavior in female mice. By contrast, no obvious role for PR can be discerned in the development of male sexual behavior.

Acute exposure to progesterone attenuates cardiac contraction by modifying myofilament calcium sensitivity in the female mouse heart

Acute application of progesterone attenuates cardiac contraction, although the underlying mechanisms are unclear. We investigated whether progesterone modified contraction in isolated ventricular myocytes and identified the Ca²⁺ handling mechanisms involved in female C57BL/6 mice (6-9 mo; sodium pentobarbital anesthesia). Cells were field-stimulated (4 Hz; 37°C) and exposed to progesterone (0.001-10.0 μM) or vehicle (35 min). Ca²⁺ transients (fura-2) and cell shortening were recorded simultaneously. Maximal concentrations of progesterone inhibited peak contraction by 71.4% (IC₅₀ = 160 ± 50 nM; n = 12) and slowed relaxation by 75.4%. By contrast, progesterone had no effect on amplitudes or time courses of underlying Ca²⁺ transients. Progesterone (1 µM) also abbreviated action potential duration. When the duration of depolarization was controlled by voltage-clamp, progesterone attenuated contraction and slowed relaxation but did not affect Ca²⁺ currents, Ca²⁺ transients, sarcoplasmic reticulum (SR) content, or fractional release of SR Ca²⁺ Actomyosin MgATPase activity was assayed in myofilaments from hearts perfused with progesterone (1 μM) or vehicle (35 min). While maximal responses to Ca²⁺ were not affected by progesterone, myofilament Ca²⁺ sensitivity was reduced (EC₅₀ = 0.94 ± 0.01 µM for control, n = 7 vs. 1.13 ± 0.05 μM for progesterone, n = 6; P < 0.05) and progesterone increased phosphorylation of myosin binding protein C. The effects on contraction were inhibited by lonaprisan (progesterone receptor antagonist) and levosimendan (Ca²⁺ sensitizer). Unlike results in females, progesterone had no effect on contraction or myofilament Ca²⁺ sensitivity in age-matched male mice. These data indicate that progesterone reduces myofilament Ca²⁺ sensitivity in female hearts, which may exacerbate manifestations of cardiovascular disease late in pregnancy when progesterone levels are high.

NEW & NOTEWORTHY

We investigated myocardial effects of acute application of progesterone. In females, but not males, progesterone attenuates and slows cardiomyocyte contraction with no effect on calcium transients. Progesterone also reduces myofilament calcium sensitivity in female hearts. This may adversely affect heart function, especially when serum progesterone levels are high in pregnancy.Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/acute-progesterone-modifies-cardiac-contraction/.

Progesterone antagonist therapy in a Pelizaeus-Merzbacher mouse model

Pelizaeus-Merzbacher disease (PMD) is a severe hypomyelinating disease, characterized by ataxia, intellectual disability, epilepsy, and premature death. In the majority of cases, PMD is caused by duplication of PLP1 that is expressed in myelinating oligodendrocytes. Despite detailed knowledge of PLP1, there is presently no curative therapy for PMD. We used a Plp1 transgenic PMD mouse model to test the therapeutic effect of Lonaprisan, an antagonist of the nuclear progesterone receptor, in lowering Plp1 mRNA overexpression. We applied placebo-controlled Lonaprisan therapy to PMD mice for 10 weeks and performed the grid slip analysis to assess the clinical phenotype. Additionally, mRNA expression and protein accumulation as well as histological analysis of the central nervous system were performed. Although Plp1 mRNA levels are increased 1.8-fold in PMD mice compared to wild-type controls, daily Lonaprisan treatment reduced overexpression at the RNA level to about 1.5-fold, which was sufficient to significantly improve the poor motor phenotype. Electron microscopy confirmed a 25% increase in the number of myelinated axons in the corticospinal tract when compared to untreated PMD mice. Microarray analysis revealed the upregulation of proapoptotic genes in PMD mice that could be partially rescued by Lonaprisan treatment, which also reduced microgliosis, astrogliosis, and lymphocyte infiltration.

Progesterone reverts LPS-reduced FAAH activity in murine peripheral blood mononuclear cells by a receptor-mediated fashion

Increased anandamide concentrations are associated with pregnancy failure. Anandamide levels are regulated by the fatty acid amide hydrolase (FAAH). The aim of the study was to investigate the role of progesterone (P) on FAAH modulation in murine peripheral blood mononuclear cells (PBMC) under septic conditions. We observed that in vivo administration of LPS to non-pregnant (NP) mice decreased FAAH activity of PBMC while in pregnant mice no changes in FAAH activity were observed. NP animals administered with P had a similar response to LPS as the pregnant animals. Also, NP mice injected with P antagonist and P showed that the effect of P on LPS-reduced FAAH activity was impaired. Furthermore, LPS produced a decrease in the ratio of PR-B/PR-A in NP animals. Our results showed that, in our model the endotoxin decreased PBMC's FAAH activity and this condition was reverted by P in a receptor-mediated fashion.

BAY 1002670: a novel, highly potent and selective progesterone receptor modulator for gynaecological therapies

STUDY QUESTION

Does the novel progesterone receptor (PR) modulator BAY 1002670, based on its preclinical pharmacological profile, offer a potential novel treatment option for uterine fibroids?

SUMMARY ANSWER

The newly synthesized BAY1002670 has proved to be a very potent, highly selective PR modulator in all in vitro and in vivo pharmacodynamics assays performed: it exhibits marked efficacy in an innovative humanized fibroid disease model, suggesting BAY 1002670 to be a very promising treatment option for uterine fibroids.

WHAT IS KNOWN ALREADY

PR inhibiting ligands have shown clinical utility in a range of potential indications and applications. Despite the emergence of the first PR antagonist >30 years ago, no agent of this compound class has been authorized in any indication for long-term application. Among other reasons, suboptimal selectivity and safety profiles of previous candidates have led to discontinuation and modification of development programmes.

STUDY, DESIGN, SIZE, DURATION

The preclinical studies include relevant in vitro and in vivo assays to clarify the properties of the PR modulator BAY 1002670 as well as a fibroid xenograft study to show directly the efficacy of BAY 1002670 on the human target tissue.

PARTICIPANTS/MATERIAL, SETTING, METHODS

BAY 1002670 was tested for binding and transactivational activity towards different human steroid receptors. Activity of the compound in the corresponding in vivo models (rat, rabbit) was assessed. Furthermore, BAY 1002670 was tested in a disease model for uterine fibroids utilizing primary human tumour tissues as xenograft in immunodeficient mice treated with estradiol (E2) and progesterone (P).

MAIN RESULT AND THE ROLE OF CHANCE

BAY1002670 in subnanomolar concentrations exhibits a highly selective binding profile and antagonistic activity for the PR. These properties are also reflected in its action in two progesterone-dependent animal models that assess the termination of pregnancy and endometrial transformation. Favourable selectivity towards other nuclear hormone receptors was demonstrated. No in vivo activity was found at the glucocorticoid, estrogenic and mineralocorticoid receptors with only weak anti-androgenic activity. In a human fibroid xenograft model BAY 1002670 showed a marked dose-dependent reduction of fibroid tumour weight gain of 95% at a dose of 3 mg/kg/day (P < 0.005).

LIMITATIONS AND REASON FOR CAUTION

Selectivity and potency of BAY 1002670 have only been determined in vitro and in animal models so far.

WIDER IMPLICATIONS OF THE FINDING

The PR modulator BAY 1002670 might offer a treatment option not only for uterine fibroids but also for other gynaecological indications.

STUDY FUNDING/COMPETING INTEREST

The studies took place at Bayer Pharma AG. All authors are employees of Bayer Pharma AG. No external funding declared.

Contraception technology: past, present and future

Steady progress in contraception research has been achieved over the past 50 years. Hormonal and nonhormonal modern contraceptives have improved women's lives by reducing different health conditions that contributed to considerable morbidity. However, the contraceptives available today are not suitable to all users, and the need to expand contraceptive choices still exists. Novel products such as new implants, contraceptive vaginal rings, transdermal patches and newer combinations of oral contraceptives have recently been introduced in family planning programs, and hormonal contraception is widely used for spacing and limiting births. Concerns over the adverse effects of hormonal contraceptives have led to research and development of new combinations with improved metabolic profile. Recent developments include use of natural compounds such as estradiol and estradiol valerate with the hope to decrease thrombotic risk, in combination with newer progestins derived from the progesterone structure or from spirolactone, in order to avoid the androgenic effects. Progesterone antagonists and progesterone receptor modulators are highly effective in blocking ovulation and preventing follicular rupture and are undergoing investigations in the form of oral pills and in semi-long-acting delivery systems. Future developments also include the combination of a contraceptive with an antiretroviral agent for dual contraception and protection against sexually transmitted diseases, to be used before intercourse or on demand, as well as for continuous use in dual-protection rings. Although clinical trials of male contraception have reflected promising results, limited involvement of industry in that area of research has decreased the likelihood of having a male method available in the current decade. Development of nonhormonal methods is still at an early stage of research, with the identification of specific targets within the reproductive system in ovaries and testes, as well as interactions between spermatozoa and ova. It is hoped that the introduction of new methods with additional health benefits would help women and couples with unmet needs to obtain access to a wider range of contraceptives with improved acceptability.

Antiprogestins in breast cancer treatment: are we ready?

Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer death in females worldwide. It is accepted that breast cancer is not a single disease, but instead constitutes a spectrum of tumor subtypes with distinct cellular origins, somatic changes, and etiologies. Molecular gene expression studies have divided breast cancer into several categories, i.e. basal-like, ErbB2 enriched, normal breast-like (adipose tissue gene signature), luminal subtype A, luminal subtype B, and claudin-low. Chances are that as our knowledge increases, each of these types will also be subclassified. More than 66% of breast carcinomas express estrogen receptor alpha (ERα) and respond to antiestrogen therapies. Most of these ER+ tumors also express progesterone receptors (PRs), the expression of which has been considered as a reliable marker of a functional ER. In this paper we will review the evidence suggesting that PRs are valid targets for breast cancer therapy. Experimental data suggest that both PR isoforms (A and B) have different roles in breast cancer cell growth, and antiprogestins have already been clinically used in patients who have failed to other therapies. We hypothesize that antiprogestin therapy may be suitable for patients with high levels of PR-A. This paper will go over the experimental evidence of our laboratory and others supporting the use of antiprogestins in selected breast cancer patients.

Relaxin improves TNF-α-induced endothelial dysfunction: the role of glucocorticoid receptor and phosphatidylinositol 3-kinase signalling

AIMS

Human relaxin-2 influences renal and cardiovascular functions. We investigated its effects on experimental endothelial dysfunction.

METHODS AND RESULTS

Acetylcholine-mediated vasodilation of rat aortic rings, impaired by 48 h tumour necrosis factor-α (TNF-α) treatment, was dose-dependently improved by relaxin co-incubation, an effect sensitive to phosphatidylinositol 3-kinase (PI3K) inhibition and the glucocorticoid receptor (GR) antagonist RU-486. TNF increased endothelial nitric oxide synthase (eNOS) phosphorylation at Thr495 and decreased total eNOS expression and both basal and stimulated eNOS activity. Relaxin co-incubation did not affect eNOS expression but improved its activity via PI3K-dependent Thr495 dephosphorylation and Ser1177 phosphorylation, and additional Ser633 phosphorylation. Via GR, relaxin attenuated the TNF-related stimulation of endothelin-1 expression, superoxide and nitrotyrosine formation, and arginase II expression. Relaxin restored, via GR-CCAAT/enhancer-binding protein-β (c/EBP-β)-mediated promoter stimulation, the compromised expression of superoxide dismutase-1 (SOD1). In rat aortic endothelial cells, relaxin activated protein kinase B (Akt) and repressed TNF-induced nuclear factor-κB and activator protein-1. Finally, the relevance of the different findings to the model used was proved by pharmacological interventions.

CONCLUSION

Relaxin improved endothelial dysfunction by promoting eNOS activity, suppressing endothelin-1 and arginase-II expression, and up-regulating SOD1 via GR, GR-c/EBP-β, and PI3K-Akt pathways. This corroborates the notion that it functions as an endogenous and potentially therapeutic vasoprotector.

Pharmacology and clinical use of sex steroid hormone receptor modulators

Sex steroid receptors are ligand-triggered transcription factors. Oestrogen, progesterone and androgen receptors form, together with the glucocorticoid and mineralocorticoid receptors, a subgroup of the superfamily of nuclear receptors. They share a common mode of action, namely translating a hormone-i.e. a small-molecule signal-from outside to changes in gene expression and cell fate, and thereby represent "natural" pharmacological targets.For pharmacological therapy, these receptors have originally been addressed by hormones and synthetic hormone analogues in order to overcome pathologies related to deficiencies in the natural ligands. Another major use for female sex hormone receptor modulators is oral contraception, i.e. birth control.On the other side, blocking the activity of sex steroid receptors has become an established way to treat hormone-dependent malignancies, such as breast and prostate cancer.In this review, we will discuss how the experience gained from the classical pharmacology of these receptors and their molecular similarities led to new options for the treatment of gender-specific diseases and highlight recent progress in medicinal chemistry of sex hormone-modulating drugs.

Synthesis and antihormonal properties of novel 11β-benzoxazole-substituted steroids

Early studies led to the identification of 11β-aryl-4',5'-dihydrospiro[estra-4,9-diene-17β,4'-oxazole] analogs with potent and more selective antiprogestational activity compared to antiglucocorticoid activity than mifepristone. In the present study, we replaced the 4'-dimethylaminophenyl group of mifepristone with the benzoxazol group to give 5a-d. We also prepared the 17β-formamido analogs 6a,b using a new synthetic strategy via the intermediate epoxide 21. These compounds were evaluated for their antagonist hormonal properties using the T47D cell-based alkaline phosphatase assay and the A549 cell-based functional assay. Compound 5c showed potent antagonist activity at GR with better selectivity for GR versus PR than mifepristone and is a promising lead for further development.

Receptor-based QSAR study for a series of 3,3-disubstituted-5-aryl oxindoles and 6-aryl benzimidazol-2-ones derivatives as progesterone receptor inhibitors

Receptor-based comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were performed on a series of 54 progesterone receptor (PR) inhibitors. The established CoMFA model from the training set gives statistically significant results with the cross-validated q (2) of 0.534 and non-cross-validated [Formula: see text] of 0.947. The best CoMSIA model was derived by the combination of steric field and hydrophobic field with a q (2) of 0.615 and [Formula: see text] of 0.954. A test set of 18 compounds was used to validate the predictive ability of the two models. The predicted correlation coefficients [Formula: see text] are 0.681 and 0.677 for CoMFA and CoMSIA models, respectively. Based on the CoMFA maps, the key structural characters of progesterone receptor inhibitors are identified. Moreover, the binding modes of oxindoles and benzimidazol-2-ones are also given by the quantum mechanical/molecular mechanical (QM/MM) calculations. This may provide useful information for drug design.

Responsiveness to PI3K and MEK inhibitors in breast cancer. Use of a 3D culture system to study pathways related to hormone independence in mice

BACKGROUND

A significant proportion of breast cancer patients face failure of endocrine therapy due to the acquisition of endocrine resistance. We have explored mechanisms involved in such disease progression by using a mouse breast cancer model that is induced by medroxyprogesterone acetate (MPA). These tumors transit through different stages of hormone sensitivity. However, when cells from tumor variants were seeded on plastic, all were stimulated by progestins and inhibited by antiprogestins such as RU486. Furthermore, cells from a RU486-resistant tumor variant recovered antiprogestin sensitivity.

HYPOTHESIS

A three-dimensional (3D) culture system, by maintaining differential cellular organization that is typical of each tumor variant, may allow for the maintenance of particular hormone responses and thus be appropriate for the study of the effects of specific inhibitors of signaling pathways associated with disease progression.

METHOD

We compared the behavior of tumors growing in vivo and cancer cells ex vivo (in 3D Matrigel). In this system, we evaluated the effects of kinase inhibitors and hormone antagonists on tumor growth.

PRINCIPAL FINDINGS

LY294002, a PI3K/AKT pathway inhibitor, decreased both tumor growth in vivo and cell survival in Matrigel in MPA-independent tumors with higher AKT activity. Induction of cell death by anti-hormones such as ICI182780 and ZK230211 was more effective in MPA-dependent tumors with lower AKT activity. Inhibition of MEK with PD98059 did not affect tumor growth in any tested variant. Finally, while Matrigel reproduced differential responsiveness of MPA-dependent and -independent breast cancer cells, it was not sufficient to preserve antiprogestin resistance of RU486-resistant tumors.

CONCLUSION

We demonstrated that the PI3K/AKT pathway is relevant for MPA-independent tumor growth. Three-dimensional cultures were useful to test the effects of kinase inhibitors on breast cancer growth and highlight the need for in vivo models to validate experimental tools used for selective therapeutic targeting.

In vitro characterization of ZK 230211--A type III progesterone receptor antagonist with enhanced antiproliferative properties

The progesterone receptor (PR) is a key regulator of female reproductive functions. Compounds with progesterone inhibiting effects (PR antagonists) have found numerous utilities in female reproductive health, ranging from contraception to potential treatment of progesterone-dependent diseases like uterine leiomyomas. Based on in vitro characteristics such as DNA binding activity and partial agonistic transcriptional behavior in the presence of protein kinase A activators (cyclic-AMP), three types of PR modulators with antagonistic properties have been defined. In this study, we analyzed the in vitro characteristics of the PR antagonist ZK 230211 in comparison to the classical antagonists onapristone and mifepristone. We focused on PR actions in genomic signaling pathways, including DNA binding activity, nuclear localization and association with the nuclear receptor corepressor (NCoR) as well as actions in non-genomic signaling, such as the activation of c-Src kinase signaling and cyclin D1 gene promoter activity. ZK 230211 represents a type of PR antagonist with increased inhibitory properties in comparison to mifepristone and onapristone. When liganded to the progesterone receptor, ZK 230211 induces a strong and persistent binding to its target response element (PRE) and increases NCoR recruitment in CV-1 cells. Furthermore, ZK 230211 displays less agonistic properties with regard to the association of PR isoform B and the cytoplasmic c-Src kinase in HeLa cells. It represses T47D cell cycle progression, in particular estradiol-induced S phase entry. In summary, our studies demonstrate ZK 230211 to be a type III progesterone receptor antagonist which is characterized by very strong DNA binding activity and strong antiproliferative effects in the cancer cell lines HeLa and T47D.

Recent patent trends in the field of progesterone receptor agonists and modulators

BACKGROUND

Progesterone receptor agonists are used in female contraception, hormone replacement therapy or some gynecological conditions like endometriosis. The interest for antagonists or selective progesterone receptor modulators (SPRMs) is growing. Recent reports on this class of compounds indicate that they could become the next generation of therapeutics in gynecological treatments.

OBJECTIVE

This overview summarizes the work on progesterone receptor agonists, SPRMs and antagonists reported in the patent literature in the past 4 years.

METHODS

The focus of the article is the examination of patents, primarily published as WO, EU or US patents since 2005. In some cases, additional data from the public literature is included into the discussion. These data are of substantial interest as the available biological data disclosed in patents are usually limited for new compound classes.

RESULTS/CONCLUSION

Some highly active clusters of compounds have been disclosed in the past 4 years. The current research seems to focus on SPRMs and progesterone receptor antagonists.

New-D-homoandrost-4,6-diene derivatives as potent progesterone receptor antagonist

The aim of this study was to synthesize three different D-homoandrostadiene derivatives (2-4) and study their biological activity. We carried out in vivo and in vitro experiments using female cycling mice, which were synchronized for estrus with luteinizing hormone-releasing hormone (LHRH) and injected with the steroidal compounds. It was also determined the binding of these compounds to the progesterone receptors (PR). Since these steroids have a new D-homoandrostandienone skeleton in their molecular structure, it was of interest also to study their binding to the androgen receptors (AR). After LHRH treatment, the mice of the control group showed the presence of 14+/-4 corpus lutea in the ovary whereas the animals treated with steroids 2-4, with RBAs of 100%, exhibited 11+/-7, 12+/-2, and 10+/-4 respectively. As a result of this study, it is evident that these steroids did not inhibit the ovulation in these animals. The uterus of the control group, showed the typical progestational activity with an enlarged endometrial thickness with a secretory activity. However, the endometrium of the mice treated with steroids 2-4 did not show an enlargement of the endometrium and no secretory activity could be detected. This fact indicates that compounds 2-4 had antagonistic activity in this tissue. The overall data show that steroids 2-4 are antagonists of the PR. However, they do not bind to the AR. These results also demonstrate that 2-4 have an antiprogestational activity in vivo, but do not decrease the number of corpus lutea in the ovary of mice treated with LHRH.

Global gene expression profiling of progesterone receptor modulators in T47D cells provides a new classification system

Progesterone receptor modulators (PRMs) play an important role in women's health. They are widely used in oral contraception or hormone therapy, and provide an attractive treatment approach for gynecological disorders such as uterine leiomyomas, endometriosis or breast cancer. Due to the broad range of activities, various studies were conducted to assess progesterone receptor antagonists (PAs) and selective progesterone receptor modulators (SPRMs) with respect to progesterone receptor (PR) agonistic and antagonistic activities in vivo. These properties are not always adequately reflected in classical in vitro models, especially differences in the agonistic potential of SPRMs, such as asoprisnil, J1042, and J912, and mixed antagonists, such as mifepristone, are not sufficiently substantiated. The effects of PRMs upon gene expression in progesterone target tissues such as breast epithelium and uterus are poorly understood. This study compares the properties of PR ligands using mammalian two-hybrid assays and gene expression profiling. The protein-protein interaction analyses in HeLa cells provide for specific ligand-induced PR conformations, whereas Affymetrix GeneChip HG-U133Plus2.0 analyses in T47D breast cancer cells indicate the transcriptional activity on the level of target genes. The analyses comprise the pure agonist R5020, the non-steroidal PR modulator PRA-910, SPRMs (J1042, asoprisnil, J912), the mixed antagonist mifepristone, classical antagonists (onapristone, ZK 137316) and the pure antagonist lonaprisan to consider all types of ligands described before. Marginal differences were identified in coactivator interaction profiles at all, but significant differences between SPRMs and PR antagonists (PAs) were observed in recruiting the LXXLL-motif containing peptide (LX-H10), very similar to in vivo activities in endometrial transformation in the rabbit (McPhail test). Global gene expression profiles demonstrated progesterone-independent effects for all PR modulators examined and emphasised similarities of asoprisnil and J1042 compared to J912 and all types of PR antagonists. In summary, the data support the popular concept of PR modulator classification in agonists, selective progesterone receptor modulators, mixed and pure antagonists. It further refines previous classification models and accentuates unique effects for each PR modulator.

Synthesis and biological effect of halogen substituted phenyl acetic acid derivatives of progesterone as potent progesterone receptor antagonists

In this paper, we report the relative binding affinities to the progesterone receptor (PR) of several progesterone derivatives containing an acetoxyphenyl substituent at C-17 and their structure-bioactivity relationship. The inhibitory effect to ovulation as well as their function as interrupters of endometrial maturation is also described. The biological activity of the novel steroids was determined in vivo and in vitro experiments using female cycling mice, which were synchronized for estrus with luteinizing hormone-releasing hormone (LHRH) and injected with the steroidal compounds. The cytosol used for the determination of the PR, was obtained from the uteri of adult estrogen-primed rabbits and the androgen (AR), mineralocorticoid (MR) and glucocorticoid (GR) receptors were determined in the cytosolic fractions from the prostate of castrated rats and from the kidneys and livers of adenalectomized male rats. We evaluated six related steroidal compounds 8a-8f differing in the nature of the 17alpha ester side chain for the inhibition of [3H] R5020 binding to the PR. The IC50 values for the displacement of [3H] R5020 binding to the PR and its relative binding affinities (RBAs) were determined. Progesterone and R5020 had similar IC(50) values; steroids 8a, 8f and 8c bind to the progesterone receptor with RBAs of 100%, whereas 8e, 8b and 8d have RBA values <100%. These data indicate that there is a relationship between the structure of these steroids and their binding activity to the progesterone receptors. Having demonstrated in this study that steroids 8a-8f bind to the PR, we also evaluated the receptor's selectivity, since some progesterone derivatives bind to AR, MR, GR receptors. We demonstrated that the tested steroids did not bind to the AR, MR, GR, since none of the steroids inhibited the labeled mibolerone, aldosterone or dexamethasone binding to the AR, MR or GR, respectively. These results show that the novel compounds have certain selectivity for the PR. After LHRH treatment, the mice of the control group showed the presence of ova in the oviduct, whereas the animals treated with steroids 8a, 8f, 8e and 8c with RBAs of 92-100%, did not exhibit any ovum in the oviducts. As a result of this study, it is evident that the novel steroids 8a, 8f, 8e and 8c inhibited the ovulation in these animals at dose of 0.22 mg/kg. After the treatment with LHRH, the uterus of the control group showed the typical progestational activity with an enlarged endometrial thickness with secretory activity. However, the endometrium of the mice treated with steroids 8a, 8f, 8e and 8c (with RBAs of 92-100%) neither did show any enlargement of the endometrium, nor a secretory activity could be detected. The diameter of the uterus was also significantly reduced compared to those of the control group, thus indicating that compounds 8a, 8f, 8e and 8c had antagonistic activity in this tissue. The overall data showed that steroids 8a, 8f, 8e and 8c have a high and selective binding activity to the PR. Furthermore there is a relationship between the structure of these steroids and their binding activity, since the presence of fluorine atom in meta position in the acetoxyphenyl substituent at C-17, improved the binding activity as compared to that for the ortho and para positions. These data also demonstrated that 8a-8f have an anti-progestational activity in vivo, and therefore they have better characteristics than the compounds previously reported.

Investigational developments for the treatment of progesterone-dependent diseases

BACKGROUND

Clinical evidence has shown that conditions such as uterine fibroids, endometriosis and breast cancer are progesterone-dependent diseases. Therefore, progesterone receptor (PR) antagonists and selective PR modulators (SPRMs) are under development for the treatment of these conditions. However, the first PR antagonists that became available exhibit insufficient selectivity or tolerability for the chronic administration required to treat these conditions. Despite initial setbacks, development of second-generation PR antagonists with better selectivity continues forward.

OBJECTIVE

In this review we would like to summarise prospects for using PR antagonists for the treatment of uterine fibroids, endometriosis and breast cancer, and to give an overview of the development of new steroidal and non-steroidal PR antagonists.

METHOD

Available preclinical and clinical data and publications have been reviewed with the focus on scientific background and use in the three mentioned indications.

RESULTS/CONCLUSION

Preclinical and clinical evidence demonstrated that PR antagonists and SPRMs are effective for the treatment of progesterone-dependent diseases. Future development will demonstrate if they can become important drugs.

Synthesis and identification of novel 11beta-aryl-4',5'-dihydrospiro[estra-4,9-diene-17beta,4'-oxazole] analogs with dissociated antiprogesterone activities

A series of novel 11beta-aryl-4',5'-dihydrospiro[estra-4,9-diene-17beta,4'-oxazole] analogs have been evaluated for their antagonist hormonal properties using the T47D cell-based alkaline phosphatase assay and the A549 cell-based functional assay. Some of the compounds showed highly potent, and more selective antiprogestational activity against antiglucocorticoid activity than mifepristone (RU 486).

Distinct temporal and spatial activities of RU486 on progesterone receptor function in reproductive organs of ovariectomized mice

RU486 is an incomplete progesterone receptor (PR) antagonist due to its partial agonist activity. To investigate the tissue-specific effects of RU486 on PR function in an ovariectomized mouse model, we used the progesterone receptor activity indicator mouse and evaluated the key determinants of progesterone-dependent gene activity: PR, coregulators, and kinases. As might be expected, acute RU486 treatment (6 h after injection) reduced PR transcriptional activity in the uterus, compared with vehicle or progesterone (P4) treatments. Chronic RU486 treatment (3 d) had a distinctly different effect on PR-mediated transcription, elevating PR activity in both the uterus and mammary gland, whereas chronic P4 treatment reduced PR activity in both tissues. This elevated uterine PR activity was associated with increased modified forms of PR and total protein levels of steroid receptor coactivator (SRC)-1 without affecting SRC-2 or SRC-3 protein levels. In addition to increased levels of coactivators, chronic RU486 treatment activated the ERK-1/2 and c-Jun N-terminal kinase signaling pathways in the uterus in a manner comparable with P4 treatment. In contrast to our observations in the uterus, chronic RU486 treatment increased modified forms of PR and the SRC-3 protein levels (but not SRC-1 and SRC-2 levels) in luminal epithelial cells of the mammary gland. Chronic RU486 also activated the c-Jun N-terminal kinase, but not ERK-1/2, signaling pathways in mammary luminal epithelial cells. This report suggests that in comparison with chronic natural hormone (P4), a mixed antagonist/agonist (RU486) induces a distinct temporal and spatial pattern of cellular genetic regulators that accompany ligand-specific gene expression.

Antiprogestin-releasing intrauterine devices: a novel approach to endometrial contraception

Intrauterine devices (IUDs) that release progestins are highly effective contraceptives, but they induce breakthrough bleeding that some women find unacceptable. Because progesterone (P) antagonists [antiprogestins (APs)] are known to suppress the endometrium, induce amenorrhea and inhibit fertility, AP-releasing IUDs (AP-IUDs) may provide an effective contraceptive that also controls endometrial bleeding. Here, we assessed the effects of empty (blank) vs. AP-IUDs (ZK 230 211) on bleeding patterns and endometrial growth in ovariectomized, artificially cycled macaques. The AP-IUDs (but not the blank controls) induced extended, frank menstruation when inserted during the late luteal phase, an indication of local AP action. Over time, endometrial glandular and arterial proliferation were inhibited, steroid receptors were elevated, spiral arteries showed degenerative changes, P withdrawal bleeding was prevented, and estradiol (E(2))-dependent proliferation was suppressed by the AP-IUDs. In sum, AP-IUDs suppressed the effects of P on endometrial progestational development and blocked the effects of E(2) on endometrial proliferation, as previously shown for systemic treatment with APs. Therefore, AP IUDs may provide novel contraceptive devices with minimal breakthrough bleeding.

Animal models of inherited neuropathies

PURPOSE OF REVIEW

Mutations in a number of genes have been associated with inherited neuropathies (Charcot-Marie-Tooth or CMT disease). This review highlights how animal models of demyelinating CMT have improved our understanding of disease mechanisms. Transgenic CMT models also allow therapies to be developed in a preclinical setting.

RECENT FINDINGS

Rodent models for the most common subtypes of human CMT disease are now available, and two mouse mutants modeling the rare CMT4B subform have lately extended this repertoire. In a peripheral myelin protein 22 kDa (Pmp22) transgenic rat model of CMT1A, administration of a progesterone receptor antagonist reduced Pmp22 overexpression, axon loss and clinical impairments. Dietary ascorbic acid prevented dysmyelination and premature death in a Pmp22 transgenic mouse line. Neurotrophin-3 promoted small fiber remyelination in CMT1A xenografts and sensory functions in CMT1A patients. Gene expression profiling in rodent models of CMT may identify further therapeutical targets. While original classifications distinguish the demyelinating and axonal forms of CMT, recent findings emphasize that axon loss is a common feature, possibly caused by Schwann cell defects rather than demyelination per se. This supports our model that myelination and long-term axonal support are distinct functions of all myelinating glial cells.

SUMMARY

Animal models have opened up new perspectives on the pathomechanisms and possible treatment strategies of inherited neuropathies.

Chronic progesterone antagonist-estradiol therapy suppresses breakthrough bleeding and endometrial proliferation in a menopausal macaque model

BACKGROUND

Clinicians routinely prescribe progestins along with estrogens during menopausal hormone therapy (HT) to block estrogen-dependent endometrial proliferation. Breakthrough bleeding (BTB) can negate the utility of this treatment. Because progestin antagonists also inhibit estrogen-dependent endometrial proliferation in women and macaques, we used a menopausal macaque model to determine whether a potent progestin antagonist (ZK 230 211, Schering AG; ZK) combined with estrogen would provide a novel mode of HT.

METHOD

Ovariectomized rhesus macaques were treated for 5 months with either estradiol (E(2)) alone, E(2) + progesterone (two doses) or E(2) + ZK (0.01, 0.05 or 0.25 mg/kg).

RESULTS

In the E(2) + progesterone groups, progesterone suppressed endometrial proliferation and induced a thick decidualized endometrium. In the E(2) + ZK 230 211 groups, all doses of ZK blocked endometrial proliferation and induced endometrial atrophy. In all ZK-treated groups, the atrophied endometrium contained some dilated glands lined by an inactive, flattened, non-mitotic epithelium. BTB was much lower in the E(2) + ZK groups (17 days of spotting, all groups) than in the E(2) and E(2) + progesterone groups (155 bleeding days, all groups). ZK suppressed E(2) effects in the cervix, but not in the vagina, oviduct or mammary glands. All serum chemistry and lipid profiles were normal.

CONCLUSION

The ability of ZK to block estrogen-dependent endometrial proliferation, induce endometrial atrophy and suppress BTB in a menopausal macaque model indicates that progestin antagonists may provide a novel mode of HT.

Myelin disorders: Causes and perspectives of Charcot-Marie-Tooth neuropathy

Charcot-Marie-Tooth (CMT) disease is a common hereditary neuropathy that causes progressive distally pronounced muscle weakness and can lead to life-long disability in patients. In most cases, the disorder has been associated with a partial duplication of human chromosome 17 (CMT1A), causing 1.5-fold overexpression of the peripheral myelin protein 22 kDa (PMP22). Increased PMP22 gene dosage results in demyelination, secondary axonal loss, and neurogenic muscle atrophy. Experimental therapeutic approaches based on the role of progesterone and ascorbic acid in myelin formation recently have reached preclinical proof-of-principle trials in rodents. It was shown that progesterone receptor antagonists can reduce PMP22 overexpression and clinical severity in a CMT1A rat model. Furthermore, ascorbic acid treatment reduced premature death and demyelination in a CMT1A mouse model. Thus, basic research has opened up new vistas for the understanding and treatment of hereditary neuropathies.