Discovery of a Potent Steroidal Glucocorticoid Receptor Antagonist with Enhanced Selectivity against the Progesterone and Androgen Receptors (OP-3633).

Structure-based modification of mifepristone (1) led to the discovery of novel mifepristone derivatives with improved selectivity profile. Addition of a methyl group at the C10 position of the steroid has a significant impact on progesterone receptor (PR) and androgen receptor (AR) activity. Within this series, OP-3633 (15) emerged as a glucocorticoid receptor (GR) antagonist with increased selectivity against PR and AR, improved cytochrome P450 inhibition profile, and significantly improved pharmacokinetic properties compared to 1. Furthermore, 15 demonstrated substantial inhibition of GR transcriptional activity in the GR positive HCC1806 triple negative breast cancer xenograft model. Overall, compound 15 is a promising GR antagonist candidate to clinically evaluate the impact of GR inhibition in reversal or prevention of therapy resistance.

Co-delivery of sorafenib and metapristone encapsulated by CXCR4-targeted PLGA-PEG nanoparticles overcomes hepatocellular carcinoma resistance to sorafenib.

BACKGROUND: Sorafenib is approved as a standard therapy for advanced hepatocellular carcinoma (HCC), but its clinical application is limited due to moderate therapeutic efficacy and high incidence of acquired resistance resulted from elevated levels of SDF-1/CXCR4 axis induced by prolonged sorafenib treatment. We previously demonstrated metapristone (RU486 metabolite) as a cancer metastatic chemopreventive agent targeting SDF-1/CXCR4 axis. Therefore, we hypothesized that combining sorafenib with metapristone could synergistically suppress cell proliferation, enhance anti-cancer activity and repress potential drug resistance. METHODS: Changes in cellular CXCR4 expression by metapristone were analyzed by RT-PCR and western blotting. Effect of combining sorafenib with metapristone on cell viability was examined by MTT assay; combination index value was calculated to evaluate the synergistic effect of combined therapy. To overcome poor pharmacokinetics and reduce off-target toxicity, CXCR4-targeted nanoparticles (NPs) were developed to co-deliver sorafenib and metapristone into CXCR4-expressing HCC in vitro and in vivo; cell proliferation, colony formation and apoptosis assays were conducted; nude mice bearing HCC xenograft were used to examine effects of this therapeutic approach on HCC progression. RESULTS: Here we showed metapristone significantly reduced CXCR4 expression in HCC. Combinatory chemotherapy of sorafenib with metapristone synergistically suppressed HCC proliferation and resistance. CXCR4-targeted PEGylated poly (lactic-co-glycolic acid) NPs conjugated with LFC131 (a peptide inhibitor of CXCR4), could deliver more sorafenib and metapristone into HCC via specific recognition and binding with transmembrane CXCR4, and resulted in the enhanced cytotoxicity, colony inhibition and apoptosis by regulating more Akt/ERK/p38 MAPK/caspase signaling pathways. Co-delivery of sorafenib with metapristone by the LFC131-conjugated NPs showed prolonged circulation and target accumulation at tumor sites, and thus suppressed tumor growth in a tumor xenograft model. CONCLUSIONS: In conclusion, co-delivery of sorafenib and metapristone via the CXCR4-targeted NPs displays a synergistic therapy against HCC. Our results suggest combinational treatment of chemotherapeutics offer an effective strategy for enhancing the therapeutic efficacy on carcinoma, and highlight the potential application of ligand-modified tumor-targeting nanocarriers in delivering drugs as a promising cancer therapeutic approach.

Novel RU486 (mifepristone) analogues with increased activity against Venezuelan Equine Encephalitis Virus but reduced progesterone receptor antagonistic activity.

There are currently no therapeutics to treat infection with the alphavirus Venezuelan equine encephalitis virus (VEEV), which causes flu-like symptoms leading to neurological symptoms in up to 14% of cases. Large outbreaks of VEEV can result in 10,000 s of human cases and mass equine death. We previously showed that mifepristone (RU486) has anti-VEEV activity (EC50 = 20 µM) and only limited cytotoxicity (CC50 > 100 µM), but a limitation in its use is its abortifacient activity resulting from its ability to antagonize the progesterone receptor (PR). Here we generate a suite of new mifepristone analogues with enhanced antiviral properties, succeeding in achieving >11-fold improvement in anti-VEEV activity with no detectable increase in toxicity. Importantly, we were able to derive a lead compound with an EC50 of 7.2 µM and no detectable PR antagonism activity. Finally, based on our SAR analysis we propose avenues for the further development of these analogues as safe and effective anti-VEEV agents.

Mifepristone Inhibits the Migration of Cervical Cancer Cells by Inhibiting Exocrine Secretion.

Cervical cancer (CC) is one of the most common gynecological malignancies, and metastasis limits the use of surgical resection. Metapristone (MIF) was reported to suppress the proliferation and migration of several cancer cells. Exosomes play a variety of roles in cellular biological processes. The relation of exosomes and CC is less studied. Cell viability, apoptosis assay and migration assay was conducted in HeLa cells treated by MIF by CCK-8 kit, staining by Annexin V-fluorescein isothiocyanate and propidium iodide, and wound test respectively. ISG15 expression level was examined in MIF-treated HeLa cells by Western blot. The migration of HeLa cells treated by MIF/GW4869 was measured by wound test. MIF suppressed the growth and migration, as well as induced apoptosis of CC cells. MIF inhibited the exocrine secretion of CC cells by upregulating ISG15, while treating CC cells by ISG15 stimulus, IFN, inhibited the secretion of exosomes. The inhibition of exocrine secretion by GW4869 enhanced the migration inhibition of MIF on CC cells. This study demonstrates that MIF suppresses the CC cell migration by inhibiting exocrine secretion through upregulating ISG1.

Metapristone (RU486 derivative) inhibits cell proliferation and migration as melanoma metastatic chemopreventive agent.

Uncontrolled cell proliferation and metastasis are the two well-known manifestations of melanoma. We hypothesized that metapristone, a potential cancer metastatic chemopreventive agent derived from mifepristone (RU486), had a dual function to fight cancer. In the present study, our findings clearly demonstrated that metapristone had modest cytostatic effect in melanoma cells. Metapristone inhibited cell viability and induced both early and late apoptosis in B16F10 and A375 cells in a time- and concentrate-dependent manner. Metapristone-treatment caused the cell arrest at the G0/G1 stage, and the inhibition of colony formation in B16F10 cells. Western blot analysis further revealed that metapristone treatment elicited a decline of Akt and ERK phosphorylation and Bcl-2, and facilitated expression of total P53 and Bax in A375 cells. In addition, cell migration and invasion were significantly suppressed by metapristone through down-regulating the expression of MMP-2, MMP-9, N-cadherin and vimentin, whereas up-regulating E-cadherin expression. Notably, metapristone exhibited anti-metastatic activity in melanoma B16F10 cells in vivo. Our results reveal metapristone, having the dual function of anti-proliferation and anti-migration for melanoma cell lines, may be a useful chemopreventive agent to reduce the risk of melanoma cancer metastasis.

Metapristone suppresses non-small cell lung cancer proliferation and metastasis via modulating RAS/RAF/MEK/MAPK signaling pathway.

BACKGROUND: Metastasis is the key phase of cancer progression that characterizes a more advanced stage and a poorer prognosis. The majority of cancer fatalities occur as a consequence of metastasis. OBJECTIVE: Mifepristone (RU486), a chemical abortifacient, has recently been used in clinical trials for psychotic depression and cancer chemotherapy. As the most predominant biological active metabolite of mifepristone, metapristone is being developed as a novel cancer metastasis chemopreventive agent by us. However, there is no information available to address the effects of metapristone on non-small cell lung cancer (NSCLC). The aim of our study was to investigate the inhibitory effect of metapristone on the proliferation and metastasis of NSCLC cells. METHOD: In the present study, we evaluated the efficacy of metapristone on the growth, migration and invasion in different kinds of NSCLC cells (A549, H1975 and H1299), and further investigated the underlying mechanism of metapristone by real time PCR and western blot assay. RESULTS: Metapristone could significantly inhibit the proliferation, migration and invasion of NSCLC cells through suppressing RAS/RAF/MEK/MAPK and PI3K/AKT signaling pathways. Moreover, metapristone could effectively inhibit the formation of NSCLC cells' cytoskeleton in a concentration-dependent manner, which possibly led to the inhibition of NSCLC cells' migration. CONCLUSION: Overall, it was preliminarily demonstrated that metapristone could be developed as a useful agent to show anti-metastasis activity for NSCLC.

Abortifacient metapristone (RU486 derivative) interrupts CXCL12/CXCR4 axis for ovarian metastatic chemoprevention.

Recent global epidemiological studies revealed the lower ovarian cancer death from long-term use of oral contraceptives. However, the underlying mechanism of action is not clear. Here, we use the abortifacient metapristone (RU486 derivative) to test the hypothesis that the contraceptives might interrupt CXCL12/CXCR4 chemokine axis to inhibit ovarian cancer metastasis. Metapristone at concentrations (

Pharmacoproteomic analysis reveals that metapristone (RU486 metabolite) intervenes E-cadherin and vimentin to realize cancer metastasis chemoprevention.

Metapristone is the most predominant biological active metabolite of mifepristone, and being developed as a novel cancer metastasis chemopreventive agent by us. Despite its prominent metastasis chemopreventive effect, the underlying mechanism remains elusive. Our study, for the first time, demonstrated that metapristone had the ability to prevent breast cancer cells from migration, invasion, and interfere with their adhesion to endothelial cells. To explore the underlying mechanism of metapristone, we employed the iTRAQ technique to assess the effect of metapristone on MDA-MB-231 cells. In total, 5,145 proteins were identified, of which, 311 proteins showed significant differences in metapristone-treated cells compared to the control group (P-value < 0.05). Bioinformatic analysis showed many differentially expressed proteins (DEPs) functionally associated with post-translational modification, chaperones, translation, transcription, replication, signal transduction, etc. Importantly, many of the DEPs, such as E-cadherin, vimentin, TGF-ß receptor I/II, smad2/3, ß-catenin, caveolin, and dystroglycan were associated with TGF-ß and Wnt signaling pathways, which were also linked to epithelial-to-mesenchymal transition (EMT) process. Further validation of the epithelial marker "E-caderin" and mesenchymal marker "vimetin" were carried out using immunoblot and immunofluorescence. These results have revealed a novel mechanism that metapristone-mediated metastasis chemoprevention is through intervening the EMT-related signaling pathways.

Thirty-day rat toxicity study reveals reversible liver toxicity of mifepristone (RU486) and metapristone.

OBJECTIVE: Mifepristone (RU486) is an oral first-line contraceptive used by hundreds of millions of women, and recently it was tested for anticancer activity in both genders worldwide. We are developing metapristone (the N-monodemethyl RU486) as a potential metastasis chemopreventive. The present acute and 30-d subacute toxicity study aimed at examining and compared in parallel the potential toxicity of the two drugs. METHODS: The single-dose acute toxicity and 30-d subacute toxicity studies were conducted in mice and rats, respectively, by gavaging metapristone or mifepristone at various doses. Blood samples and organs were collected for blood chemistry, hematology and histology analyses. RESULTS: Oral mifepristone (3000 mg/kg) caused 30% and 40% death in female and male mice, respectively, within 15 h post-dosing. In comparison, the same dose of metapristone produced 30% acute death in males only. Thirty-day oral administration of the two drugs to rats (12.5, 50 and 200 mg/kg/day) caused reversible hepatotoxicity that only occurred at 200 mg/kg/day group, evidenced by the elevated liver enzyme activity and liver organ weight. CONCLUSION: The present study, for the first time, reveals reversible hepatotoxicity in rats caused by the 30-d consecutive administration at the high dose, and warns the potential hepatotoxicity caused by long-term administrations of high doses of mifepristone or metapristone in clinical trials but not by the acute single abortion doses.

In vitro and in vivo efficacy and safety evaluation of metapristone and mifepristone as cancer metastatic chemopreventive agents.

Malignant melanoma, the most deadly form of skin cancer, has a high propensity for metastatic spread and is notoriously chemotherapy-resistant. Metapristone is the primary metabolite of mifepristone (RU486) and shows biological activities similar to RU486. In the present study, we comprehensively investigated the efficacy of metapristone as a metastatic chemopreventive against melanoma B16F10 cells in vitro and in vivo, and evaluated the safety profile of both drugs in mice. Metapristone showed less cytostatic effect in vitro and in vivo in comparison with mifepristone. However, metapristone interfered the adhesion of B16F10 cells to fibronectin by down-regulating cellular expression of integrin α4. Chemopreventive pretreatment followed by oral administration of metapristone and mifepristone (2.5, 10, 50 mg/kg/day for 35 days) to melanoma C57BL/6 mouse model showed significant attenuation of pulmonary metastatic development. Oral administration of high doses of metapristone and mifepristone to normal mice for 35 days (25, 100, 250 mg/kg/day) resulted in a dose-dependent increase in mouse liver weight that was more severe with mifepristone than metapristone. The long-term toxicity study revealed more changes by mifepristone in counts of erythrocytes, leukocytes and platelets than by metapristone. In conclusion, metapristone may fit into a new class of cancer metastatic chemopreventive agents. It showed a safety and efficacy profile better than mifepristone.

A novel UPLC/MS/MS method for rapid determination of metapristone in rat plasma, a new cancer metastasis chemopreventive agent derived from mifepristone (RU486).

Mifepristone (RU486) is a chemical abortifacient used by hundreds of millions of women world-wide. It has recently been used in clinical trials for psychotic depression and cancer chemotherapy. Metapristone is the most predominant biological active metabolite of mifepristone, and being developed as a novel cancer metastasis chemopreventive agent based on its unique pharmacological properties. In this study, a novel rapid and sensitive method using UPLC/MS/MS was developed and validated for quantitative analysis of metapristone in plasma, which used less plasma volume and was demonstrated to be more simple and low-cost than the published methods. Metapristone in plasma was recovered by liquid-liquid extraction using 1 mL of ethyl acetate and chromatographic separation was carried on a C18 column at 35 °C, with a gradient mobile phase consisting of methanol and water containing 0.1% (v/v) formic acid at a flow rate of 0.3 mL/min. The mass spectrometric detection was carried out using a triple-quadrupole system via positive electrospray ionization. Multiple reaction monitoring was used for quantitation of m/z transitions from 416.3 to 119.9 for metapristone and from 313.1 to 109 for levonorgestrel (internal standard). Good linearity (r²> 0.9926) was achieved over a concentration range from 7.1 to 2840 ng/mL with a lower limit of quantification of 7.1 ng/mL for metapristone. The intra- and inter-day variations of the assay were 2.4-10.0% relative standard deviation with an accuracy of -5.6 to 8.6% relative error. This newly developed method was successfully applied to a pharmacokinetic study that revealed, for the first time, that there was a significant difference in pharmacokinetic profile between genders.

Synthesis, spectral characterization, and in vitro cellular activities of metapristone, a potential cancer metastatic chemopreventive agent derived from mifepristone (RU486).

Mifepristone (RU486) is marketed and used widely by women as an abortifacient, and experimentally for psychotic depression and anticancer treatments. After administration, metapristone is found to be the most predominant metabolite of mifepristone. We hypothesized that adhesion of circulating tumor cells (CTCs) to vascular endothelial bed is a crucial starting point in metastatic cascade, and that metapristone can serve as a cancer metastatic chemopreventive agent that can interrupt adhesion and invasion of CTCs to the intima of microvasculature. In the present study, we modified the synthesis procedure to produce grams of metapristone, fully characterized its spectral properties and in vitro cellular activities, including its cytostatic effects, cell cycle arrest, mitochondrial membrane potential, and apoptosis on human colorectal cancer HT-29 cells. Metapristone concentration dependently interrupted adhesion of HT-29 cells to endothelial cells. Metapristone may potentially be a useful agent to interrupt metastatic initiation.

Synthesis and biological evaluation of partially fluorinated antiprogestins and mesoprogestins.

A series of antiprogestins have been synthesized by partially fluorinating the steroid molecule in positions relevant for receptor binding. By introducing fluorine at the exo-methylene of the 17 spirofuran ring, we obtained partial agonists (mesoprogestins) with significant applications for antiproliferative and antiovulatory treatment strategies in gynecological therapy such as uterine fibroids, endometriosis and heavy menstrual bleeding. Compared to the standard drug RU486, our synthesized compounds exhibited considerable dissociation between antiprogestational and antiglucocorticoid PR receptors. Furthermore, our studies have shown that pure antiprogestins can be generated by partially fluorinating the 17 propenyl and propynl group or by substituting the 4' acetyl phenyl group in the 11 position using trifluromethyl group.

Differential effect of glucocorticoid receptor antagonists on glucocorticoid receptor nuclear translocation and DNA binding.

The effects of RU486 and S-P, a more selective glucocorticoid receptor antagonist from Schering-Plough, were investigated on glucocorticoid receptor nuclear translocation and DNA binding. In the in vitro study, AtT20 cells were treated with vehicle or with RU486, S-P or corticosterone (3-300 nM) or co-treated with vehicle or glucocorticoid receptor antagonists (3-300 nM) and 30 nM corticosterone. Both glucocorticoid receptor antagonists induced glucocorticoid receptor nuclear translocation but only RU486 induced DNA binding. RU486 potentiated the effect of corticosterone on glucocorticoid receptor nuclear translocation and DNA binding, S-P inhibited corticosterone-induced glucocorticoid receptor nuclear translocation, but not glucocorticoid receptor-DNA binding. In the in vivo study, adrenalectomized rats were treated with vehicle, RU486 (20 mg/kg) and S-P (50 mg/kg) alone or in combination with corticosterone (3 mg/kg). RU486 induced glucocorticoid receptor nuclear translocation in the pituitary, hippocampus and prefrontal cortex and glucocorticoid receptor-DNA binding in the hippocampus, whereas no effect of S-P on glucocorticoid receptor nuclear translocation or DNA binding was observed in any of the areas analysed. These findings reveal differential effects of RU486 and S-P on areas involved in regulation of hypothalamic-pituitary-adrenal axis activity in vivo and they are important in light of the potential use of this class of compounds in the treatment of disorders associated with hyperactivity of the hypothalamic-pituitary-adrenal axis.

Suppressive effect of dexamethasone on TIMP-1 production involves murine osteoblastic MC3T3-E1 cell apoptosis.

High dose glucocorticoid (GC) treatment induces osteoporosis partly via increasing osteoblast apoptosis. However, the mechanism of GC-induced apoptosis has not been fully elucidated. Osteoblast-derived tissue inhibitor of metalloproteinase-1 (TIMP-1) was recently reported to be involved in bone metabolism. Our previous study demonstrated that TIMP-1 suppressed apoptosis of the mouse bone marrow stromal cell line MBA-1 (pre-osteoblast) induced by serum deprivation. Therefore, we tested the effect of the GC dexamethasone (Dex) on TIMP-1 production in murine osteoblastic MC3T3-E1 cells and further determined whether this action is associated with Dex-induced osteoblast apoptosis. Dex decreased TIMP-1 production in MC3T3-E1 cells, and this effect was blocked by the glucocorticoid receptor (GR) antagonists, RU486 and RU40555. Recombinant TIMP-1 protein reduced caspase-3 activation and apoptosis induced by Dex in MC3T3-E1 cells. In addition, the pro-apoptotic effect of the Dex was augmented by suppression of TIMP-1 with siRNA. Furthermore, mutant TIMP-1, which has no inhibitory effects on MMPs, yet protects MC3T3-E1 cells against Dex-induced apoptosis. Our study demonstrates that Dex suppresses TIMP-1 production in osteoblasts through GR, and this effect is associated with its induction of osteoblast apoptosis. The anti-apoptotic action of TIMP-1 is independent of its inhibitory effects on MMPs activities. The decrease in TIMP-1 production caused by Dex may contribute to the mechanisms of Dex-induced bone loss.

Syntheses and antigestagenic activity of mifepristone derivatives.

A series of mifepristone derivatives with different "linker groups" in position 4' of the phenyl ring in the 11beta-position of the steroid scaffold (2-41) have been synthesized. Their antigestagenic activites were determined in a cell-based assay (alkali phosphatase assay in T47-D breast cancer cells) and compared with that of the parent compound mifepristone. SAR and QSAR studies reveal the influence of both lipophilicity and partial charge based van der Waals surface area descriptors on biological activity. Within the series of compounds described in this study, three mifepristone derivatives are identified with considerably high antigestagenic activity. These compounds are regarded as useful starting materials for the synthesis of either physiologically stable or cleavable progesterone receptor-binding conjugates for therapeutic or diagnostic purposes.

Simultaneous determination of mifepristone and monodemethyl-mifepristone in human plasma by liquid chromatography-tandem mass spectrometry method using levonorgestrel as an internal standard: application to a pharmacokinetic study.

A rapid and sensitive liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed and validated to simultaneously determine mifepristone and monodemethyl-mifepristone in human plasma using levonorgestrel as the internal standard (IS). After solid-phase extraction of the plasma samples, mifepristone, monodemethyl-mifepristone and the IS were subjected to LC-MS/MS analysis using electro-spray ionization (ESI) in the multiple reaction monitoring (MRM) mode. Chromatographic separation was performed on an XTERRA MS C(18) column (150 x 2.1 mm i.d., 5 microm). The method had a chromatographic run time of 4.5 min and linear calibration curves over the concentration ranges of 5-2000 ng/mL for mifepristone and monodemethyl-mifepristone. The recoveries of the method were found to be 94.5-103.7% for mifepristone and 70.7-77.3% for monodemethyl-mifepristone. The method had a lower limit of quantification (LLOQ) of 5.0 ng/mL and a lower limit of detection (LOD) of 1.0 ng/mL for both mifepristone and monodemethyl-mifepristone. The intra- and inter-batch precision was less than 15% for all quality control samples at concentrations of 10, 100 and 1000 ng/mL. These results indicate that the method was efficient with a short run time (4.5 min) and acceptable accuracy, precision and sensitivity. The validated LC-MS/MS method was successfully used in a pharmacokinetic study in healthy female volunteers after oral administration of 25 mg mifepristone tablet.

Glucocorticoid receptor activation is involved in producing abnormal phenotypes of single-prolonged stress rats: a putative post-traumatic stress disorder model.

Post-traumatic stress disorder (PTSD) is a stress-related mental disorder caused by traumatic experience, and presents with characteristic symptoms, such as intrusive memories, a state of hyperarousal, and avoidance, that endure for years. Single-prolonged stress (SPS) is one of the animal models proposed for PTSD. Rats exposed to SPS showed enhanced inhibition of the hypothalamo-pituitary-adrenal (HPA) axis, which has been reliably reproduced in patients with PTSD, and increased expression of glucocorticoid receptor (GR) in the hippocampus. In this study, we characterized further neuroendocrinologic, behavioral and electrophysiological alterations in SPS rats. Plasma corticosterone recovered from an initial increase within a week, and gross histological changes and neuronal cell death were not observed in the hippocampus of the SPS rats. Behavioral analyses revealed that the SPS rats presented enhanced acoustic startle and impaired spatial memory that paralleled the deficits in hippocampal long-term potentiation (LTP) and depression. Contextual fear memory was enhanced in the rats 1 week after SPS exposure, whereas LTP in the amygdala was blunted. Interestingly, blockade of GR activation by administering 17-beta-hydroxy-11-beta-/4-/[methyl]-[1-methylethyl]aminophenyl/-17-alpha-[prop-1-ynyl]estra-4-9-diene-3-one (RU40555), a GR antagonist, prior to SPS exposure prevented potentiation of fear conditioning and impairment of LTP in the CA1 region. Altogether, SPS caused a number of behavioral changes similar to those described in PTSD, which marks SPS as a putative PTSD model. The preventive effects of a GR antagonist suggested that GR activation might play a critical role in producing the altered behavior and neuronal function of SPS rats.

Synthesis of C-11 modified mifepristone analog libraries.

Substitution of the C-11 aniline of mifepristone can provide compounds with altered pharmacokinetic and pharmacodynamic (PK/PD) profiles that may find use for new indications. The development of new steroid intermediates and specialized library synthesis methods were required to enable the efficient preparation of structurally complex C-11 modified mifepristone analogs.

Parallel strategies for the preparation and selection of liver-targeted glucocorticoid receptor antagonists.

Libraries of mifepristone analogs, MP-Acids, were designed and synthesized to increase the chances of identifying GR antagonists that possess liver-selective pharmacological profiles. MP-Acids were uniformly potent GR antagonists in binding and in cell-based functional assays. A high throughput pharmacokinetic selection strategy that employs the cassette dosing of MP-Acids was developed to identify liver-targeting compounds. Thus, resource-intensive in vivo assays to measure liver-selective pharmacology were enriched with GR antagonists that achieve high concentrations in the liver.