Regression of uterine leiomyomata in response to the antiprogesterone RU 486

Clinical Utility of Mifepristone: Apprising the Expanding Horizons

Mifepristone is a progesterone and glucocorticoid receptor antagonist. Medical abortion with mifepristone and prostaglandin has revolutionized the abortion process extending abortion care to the doors of females. From as low as 2 mg/day to doses extending to 600 mg, from daily dosing to single dosage treatment, mifepristone has a wide perspective in the treatment of various pathologies. Cervical dilatation and myometrial contractility have made the utility of mifepristone feasible for second-trimester termination of pregnancy and induction of labor awaiting Food and Drug Administration approvals. Its anti-progesterone action on the menstrual cycle has a new dimension of use as a contraceptive, as well as use as a menstruation inductive agent. Its role in endometriosis, ectopic pregnancy, and adenomyosis requires more intensive research. Apoptotic action of mifepristone, interference of heterotypic cell adhesion to the basement membrane, cell migration, growth inhibition of various cancer cell lines, decreased epidermal growth factor expression, suppression of invasive and metastatic cancer potential, increase in tumor necrosis factor, downregulation of cyclin-dependent kinase 2, B-cell lymphoma 2, and Nuclear factor kappa B have opened its potential to be explored as anti-cancer treatment and its effects on leiomyoma. The drug needs to be studied more for the prospectus of its anti-glucocorticoid actions in a wider dimension beyond its acquiescence for the treatment of Cushing syndrome.

PXR mediates mifepristone-induced hepatomegaly in mice

Mifepristone (Mif), an effective synthetic steroidal antiprogesterone drug, is widely used for medical abortion and pregnancy prevention. Due to its anti-glucocorticoid effect, high-dose Mif is also used to treat Cushing's syndrome. Mif was reported to active pregnane X receptor (PXR) in vitro and PXR can induce hepatomegaly via activation and interaction with yes-associated protein (YAP) pathway. High-dose Mif was reported to induce hepatomegaly in rats and mice, but the underlying mechanism remains unclear. Here, the role of PXR was studied in Mif-induced hepatomegaly in C57BL/6 mice and Pxr-knockout mice. The results demonstrated that high-dose Mif (100 mg · kg^-1 · d^-1, i.p.) treatment for 5 days significantly induced hepatomegaly with enlarged hepatocytes and promoted proliferation, but low dose of Mif (5 mg · kg^-1 · d^-1, i.p.) cannot induce hepatomegaly. The dual-luciferase reporter gene assays showed that Mif can activate human PXR in a concentration-dependent manner. In addition, Mif could promote nuclear translocation of PXR and YAP, and significantly induced the expression of PXR, YAP, and their target proteins such as CYP3A11, CYP2B10, UGT1A1, ANKRD, and CTGF. However, Mif (100 mg · kg^-1 · d^-1, i.p.) failed to induce hepatomegaly in Pxr-knockout mice, as well as hepatocyte enlargement and proliferation, further indicating that Mif-induced hepatomegaly is PXR-dependent. In summary, this study demonstrated that PXR-mediated Mif-induced hepatomegaly in mice probably via activation of YAP pathway. This study provides new insights in Mif-induced hepatomegaly, and provides novel evidence on the crucial function of PXR in liver enlargement and regeneration.

Association between vitamin D and uterine fibroids: a study protocol of an open-label, randomised controlled trial

INTRODUCTION

Uterine fibroids are the most common pelvic benign tumour with no satisfactory long-term medical treatment. Recent studies have demonstrated that vitamin D significantly inhibited the growth of fibroids in vitro, vivo and a small-sample clinical trial. Therefore, the aim of this randomised clinical trial (RCT) is to evaluate whether supplementation with vitamin D could reduce the risk and inhibit the growth of uterine fibroids in reproductive stage women.

METHODS AND ANALYSIS

The open-label, RCT comprises two parts, including parts I and II. In part I, 2230 vitamin D deficiency or vitamin D insufficiency patients without uterine fibroids will be randomly assigned to two groups: intervention group (according to the level of serum 25-hydroxyvitamin D₃, receive 1600 or 800 IU/day of vitamin D₃ for 2 years) and control group (followed up at the same time points). By using gynaecological ultrasound examinations, the incidence of uterine fibroids will be employed to measure the outcome in different groups. In part II, 360 uterine fibroids patients with vitamin D deficiency or vitamin D insufficiency will be randomly assigned to intervention group or control group. According to the level of serum 25-hydroxyvitamin D₃, 180 patients will receive 1600 or 800 IU/day of vitamin D₃ for 2 years. Control group will receive regular follow-up. The outcome measure will be conducted using gynaecological ultrasound examinations to detect the growth of uterine fibroids in each group.

ETHICS AND DISSEMINATION

This study has been approved by the institutional review board of the Second Affiliated Hospital of Wenzhou Medical University (No. LCKY2018-35).

TRIAL REGISTRATION NUMBERS

NCT03586947 and NCT03584529.

Safety and efficacy of the selective progesterone receptor modulator asoprisnil for heavy menstrual bleeding with uterine fibroids: pooled analysis of two 12-month, placebo-controlled, randomized trials

STUDY QUESTION

Can asoprisnil, a selective progesterone receptor modulator, provide clinically meaningful improvements in heavy menstrual bleeding (HMB) associated with uterine fibroids with an acceptable safety profile?

SUMMARY ANSWER

Uninterrupted treatment with asoprisnil for 12 months effectively controlled HMB and reduced fibroid and uterine volume with few adverse events.

WHAT IS KNOWN ALREADY

In a 3-month study, asoprisnil (5, 10 and 25 mg) suppressed uterine bleeding, reduced fibroid and uterine volume, and improved hematological parameters in a dose-dependent manner.

STUDY DESIGN, SIZE, DURATION

In two Phase 3, double-blind, randomized, placebo-controlled, multicentre studies, women received oral asoprisnil 10 mg, asoprisnil 25 mg or placebo (2:2:1) once daily for up to 12 months.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Premenopausal women ≥18 years of age in North America with HMB associated with uterine fibroids were included (N = 907). The primary efficacy endpoint was the percentage of women who met all three predefined criteria at 12 months or the final month for patients who prematurely discontinued: (1) ≥50% reduction in monthly blood loss (MBL) by menstrual pictogram, (2) hemoglobin concentration ≥11 g/dL or an increase of ≥1 g/dL, and (3) no interventional therapy for uterine fibroids. Secondary efficacy endpoints included changes in other menstrual bleeding parameters, volume of the largest fibroids, uterine volume and health-related quality of life (HRQL).

MAIN RESULTS AND THE ROLE OF CHANCE

In all, 90% and 93% of women in the asoprisnil 10-mg and 25-mg groups, respectively, and 35% of women in the placebo group met the primary endpoint (P < 0.001). Similar results were observed at month 6 (P < 0.001). The percentage of women who achieved amenorrhea in any specified month ranged from 66-78% in the asoprisnil 10-mg group and 83-93% in the asoprisnil 25-mg group, significantly higher than with placebo (3-12%, P < 0.001). Hemoglobin increased rapidly (by month 2) with asoprisnil treatment and was significantly higher versus placebo throughout treatment. The primary fibroid and uterine volumes were significantly reduced from baseline through month 12 with asoprisnil 10 mg (median changes up to -48% and -28%, respectively) and 25 mg (median changes up to -63% and -39%, respectively) versus placebo (median changes up to +16% and +13%, respectively; all P < 0.001). Dose-dependent, significant improvements in HRQL (Uterine Fibroid Symptom and Quality of Life instrument) were observed with asoprisnil treatment. Asoprisnil was generally well tolerated. Endometrial biopsies indicated dose- and time-dependent decreases in proliferative patterns and increases in quiescent or minimally stimulated endometrium at month 12 of treatment. Although not statistically significantly different at month 6, mean endometrial thickness at month 12 increased by ~2 mm in both asoprisnil groups compared with placebo (P < 0.01). This effect was associated with cystic changes in the endometrium on MRI and ultrasonography, which led to invasive diagnostic and therapeutic procedures in some asoprisnil-treated women.

LIMITATIONS, REASONS FOR CAUTION

Most study participants were black; few Asian and Hispanic women participated. The study duration may have been insufficient to fully characterize the endometrial effects.

WIDER IMPLICATIONS OF THE FINDINGS

Daily uninterrupted treatment with asoprisnil was highly effective in controlling menstrual bleeding, improving anemia, reducing fibroid and uterine volume, and increasing HRQL in women with HMB associated with uterine fibroids. However, this treatment led to an increase in endometrial thickness and invasive diagnostic and therapeutic procedures, with potential unknown consequences.

STUDY FUNDING/COMPETING INTEREST(S)

This trial was funded by AbbVie Inc. (prior sponsors: TAP Pharmaceutical Products Inc., Abbott Laboratories). E.A. Stewart was a site investigator in the Phase 2 study of asoprisnil and consulted for TAP during the design and conduct of these studies while at Harvard Medical School and Brigham and Women's Hospital. She received support from National Institutes of Health grants HD063312, HS023418 and HD074711 and research funding, paid to Mayo Clinic for patient care costs related to an NIH-funded trial from InSightec Ltd. She consulted for AbbVie, Allergan, Bayer HealthCare AG, Gynesonics, and Welltwigs. She received royalties from UpToDate and the Med Learning Group. M.P. Diamond received research funding for the conduct of the studies paid to the institution and consulted for AbbVie. He is a stockholder and board and director member of Advanced Reproductive Care. He has also received funding for study conduct paid to the institution from Bayer and ObsEva. A.R.W. Williams consulted for TAP and Repros Therapeutics Inc. He has current consultancies with PregLem SA, Gedeon Richter, HRA Pharma and Bayer. B.R. Carr consulted for and received research funding from AbbVie. E.R. Myers consulted for AbbVie, Allergan and Bayer. R.A. Feldman received compensation for serving as a principal investigator and participating in the conduct of the trial. W. Elger was co-inventor of several patents related to asoprisnil. C. Mattia-Goldberg is a former employee of AbbVie and may own AbbVie stock or stock options. B.M. Schwefel and K. Chwalisz are employees of AbbVie and may own AbbVie stock or stock options.

TRIAL REGISTRATION NUMBER

NCT00152269, NCT00160381 (clinicaltrials.gov).

TRIAL REGISTRATION DATE

7 September 2005; 8 September 2005.

DATE OF FIRST PATIENT’S ENROLMENT

12 September 2002; 6 September 2002.

90 YEARS OF PROGESTERONE: Selective progesterone receptor modulators in gynaecological therapies

Abnormal uterine bleeding (AUB) is a chronic, debilitating and common condition affecting one in four women of reproductive age. Current treatments (conservative, medical and surgical) may be unsuitable, poorly tolerated or may result in loss of fertility. Selective progesterone receptor modulators (SPRMs) influence progesterone-regulated pathways, a hormone critical to female reproductive health and disease; therefore, SPRMs hold great potential in fulfilling an unmet need in managing gynaecological disorders. SPRMs in current clinical use include RU486 (mifepristone), which is licensed for pregnancy interruption, and CDB-2914 (ulipristal acetate), licensed for managing AUB in women with leiomyomas and in a higher dose as an emergency contraceptive. In this article, we explore the clinical journey of SPRMs and the need for further interrogation of this class of drugs with the ultimate goal of improving women's quality of life.

The Selective Progesterone Receptor Modulator Ulipristal Acetate Inhibits the Activity of the Glucocorticoid Receptor

CONTEXT

The selective progesterone modulator ulipristal acetate (ulipristal) offers a much-needed therapeutic option for the clinical management of uterine fibroids. Although ulipristal initially passed safety evaluations in Europe, postmarketing analysis identified cases of hepatic injury and failure, leading to restrictions on the long-term use of ulipristal. One of the factors potentially contributing to significant side effects with the selective progesterone modulators is cross-reactivity with other steroid receptors.

OBJECTIVE

To determine whether ulipristal can alter the activity of the endogenous glucocorticoid receptor (GR) in relevant cell types.

DESIGN

Immortalized human uterine fibroid cells (UtLM) and hepatocytes (HepG2) were treated with the synthetic glucocorticoid dexamethasone and/or ulipristal. Primary uterine fibroid tissue was isolated from patients undergoing elective gynecological surgery and treated ex vivo with dexamethasone and/or ulipristal. In vivo ulipristal exposure was performed in C57Bl/6 mice to measure the effect on basal gene expression in target tissues throughout the body.

RESULTS

Dexamethasone induced the expression of established glucocorticoid-target genes period 1 (PER1), FK506 binding protein 51 (FKBP5), and glucocorticoid-induced leucine zipper (GILZ) in UtLM and HepG2 cells, whereas cotreatment with ulipristal blocked the transcriptional response to glucocorticoids in a dose-dependent manner. Ulipristal inhibited glucocorticoid-mediated phosphorylation, nuclear translocation, and DNA interactions of GR. Glucocorticoid stimulation of PER1, FKBP5, and GILZ was abolished by cotreatment with ulipristal in primary uterine fibroid tissue. The expression of glucocorticoid-responsive genes was decreased in the lung, liver, and uterus of mice exposed to 2 mg/kg ulipristal. Interestingly, transcript levels of Fkbp5 and Gilz were increased in the hippocampus and pituitary.

CONCLUSIONS

These studies demonstrate that ulipristal inhibits endogenous glucocorticoid signaling in human fibroid and liver cells, which is an important consideration for its use as a long-term therapeutic agent.

Uterine fibroids: an update on current and emerging medical treatment options

Uterine fibroids are the most common gynecological disorder, classically requiring surgery when symptomatic. Although attempts at finding a nonsurgical cure date back to centuries, it is only around the middle of the last century that serious attempts at a medical treatment were carried out. Initially, both progestins and estrogen–progestin combinations have been utilized, although proof of their usefulness is lacking. A major step forward was achieved when peptide analogs of the GnRH were introduced, first those with superagonist properties and subsequently those acting as antagonists. Initially, the latter produced side effects preventing their routine utilization; eventually, this problem was overcome following the synthesis of cetrorelix. Because both types of analogs produce hypoestrogenism, their use is limited to a maximum of 6 months and, for this reason, today they are utilized as an adjuvant treatment before surgery with overall good results. Over the last decade, new, nonpeptidic, orally active GnRH-receptor blockers have also been synthesized. One of them, Elagolix, is in the early stages of testing in women with fibroids. Another fundamental development has been the utilization of the so-called selective progesterone receptor modulators, sometimes referred to as “antiprogestins”. The first such compound to be applied to the long-term treatment of fibroids was Mifepristone; today, this compound is mostly used outside of Western Countries, where the substance of choice is Ulipristal acetate. Large clinical trials have proven the effectiveness of Ulipristal in the long-term medical therapy of fibroids, although some caution must be exercised because of the rare occurrence of liver complications. All selective progesterone receptor modulators produce unique endometrial changes that are today considered benign, reversible, and without negative consequences. In conclusion, long-term medical treatment of fibroids seems possible today, especially in premenopausal women.

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.

Current medical treatment of uterine fibroids

Uterine fibroids (leiomyomas or myomas), benign monoclonal tumors, are the most common benign tumors in women. Heavy or prolonged menstrual bleeding, abnormal uterine bleeding, resultant anemia, pelvic pain, infertility, and/or recurrent pregnancy loss are generally associated with uterine fibroids. Although curative treatment of this tumor relies on surgical therapies, medical treatments are considered the first-line treatment to preserve fertility and avoid or delay surgery. The aim of this review is to provide available and emerging medical treatment options for symptomatic uterine fibroids. Literature review and consensus of expert opinion. Many uterine fibroids are asymptomatic and require no intervention, although it is advisable to follow-up patients to document stability in size and growth. Fibroid-associated symptoms include heavy menstrual bleeding and pain or pelvic discomfort. The association between infertility and fibroids increases with age. Treatment options for symptomatic uterine fibroids - include medical, surgical, and radiologically guided interventions. Various medical therapies are now available for women with uterine fibroids, although each therapy has its own advantages and disadvantages. Currently, gonadotrophin-releasing hormone (GnRH) agonists and selective progesterone receptor modulators (SPRMs) are the most effective medical therapies, with the most evidence to support their reduction of fibroid volume and symptomatic improvement in menstrual bleeding. The choice of treatment depends on the patient's personal treatment goals, as well as efficacy and need for repeated interventions.

A Comprehensive Review of the Pharmacologic Management of Uterine Leiomyoma

Uterine leiomyomata are the most common benign tumors of the gynecologic tract impacting up to 80% of women by 50 years of age. It is well established that these tumors are the leading cause for hysterectomy with an estimated total financial burden greater than $30 billion per year in the United States. However, for the woman who desires future fertility or is a poor surgical candidate, definitive management with hysterectomy is not an optimal management plan. Typical gynecologic symptoms of leiomyoma include infertility, abnormal uterine bleeding (AUB)/heavy menstrual bleeding (HMB) and/or intermenstrual bleeding (IMB) with resulting iron-deficiency anemia, pelvic pressure and pain, urinary incontinence, and dysmenorrhea. The morbidity caused by these tumors is directly attributable to increases in tumor burden. Interestingly, leiomyoma cells within a tumor do not rapidly proliferate, but rather the increase in tumor size is secondary to production of an excessive, stable, and aberrant extracellular matrix (ECM) made of disorganized collagens and proteoglycans. As a result, medical management should induce leiomyoma cells toward dissolution of the extracellular matrix, as well as halting or inhibiting cellular proliferation. Herein, we review the current literature regarding the medical management of uterine leiomyoma.

Accelerated Episodic Luteinizing Hormone Release Accompanies Blunted Progesterone Regulation in PCOS-like Female Rhesus Monkeys (Macaca Mulatta) Exposed to Testosterone during Early-to-Mid Gestation

BACKGROUND/AIMS

Ovarian theca cell hyperandrogenism in women with polycystic ovary syndrome (PCOS) is compounded by androgen receptor-mediated impairment of estradiol and progesterone negative feedback regulation of episodic luteinizing hormone (LH) release. The resultant LH hypersecretion, likely the product of accelerated episodic release of gonadotropin-releasing hormone (GnRH) from the median eminence of the hypothalamus, hyperstimulates ovarian theca cell steroidogenesis, enabling testosterone (T) and androstenedione excess. Prenatally androgenized (PA) female monkeys exposed to fetal male levels of T during early-to-mid gestation, when adult, demonstrate PCOS-like traits, including high T and LH levels. This study tests the hypothesis that progesterone resistance-associated acceleration in episodic LH release contributes to PA monkey LH excess.

METHODS

A total of 4 PA and 3 regularly cycling, healthy control adult female rhesus monkeys of comparable age and body mass index underwent (1) a 10 h, frequent intravenous sampling assessment for LH episodic release, immediately followed by (2) IV infusion of exogenous GnRH to quantify continuing pituitary LH responsiveness, and subsequently (3) an SC injection of a progesterone receptor antagonist, mifepristone, to examine LH responses to blockade of progesterone-mediated action.

RESULTS

Compared to controls, the relatively hyperandrogenic PA females exhibited ~100% increase (p = 0.037) in LH pulse frequency, positive correlation of LH pulse amplitude (p = 0.017) with androstenedione, ~100% greater increase (p = 0.034) in acute (0-10 min) LH responses to exogenous GnRH, and an absence (p = 0.008) of modest LH elevation following acute progesterone receptor blockade suggestive of diminished progesterone negative feedback.

CONCLUSION

Such dysregulation of LH release in PCOS-like monkeys implicates impaired feedback control of episodic release of hypothalamic GnRH reminiscent of PCOS neuroendocrinopathy.

Progesterone Receptor Isoforms, Nuclear Corepressor-1 and Steroid Receptor Coactivator-1 and B-Cell Lymphoma 2 and Akt and Akt Phosphorylation Status in Uterine Myomas after Ulipristal Acetate Treatment: A Systematic Immunohistochemical Evaluation

OBJECTIVE

To investigate whether ulipristal acetate (UPA) treatment modifies the expression of progesterone receptor (PR), its nuclear cofactors steroid receptor coactivator-1 (SRC1) and nuclear corepressor-1 (NCoR1), prosurvival factor B-cell lymphoma 2 (Bcl-2), and Akt in uterine myomas.

PATIENTS

Prospective study of 59 women with symptomatic myomas undergoing myomectomy. Forty-two patients were treated preoperatively with UPA; the remaining 17 were not and they served as controls.

METHOD

Tissue microarrays were obtained from surgical specimens and immunohistochemistry was performed. Blinded quantification of expression of PR (PR-A vs. PR-B), coactivator SRC1 and corepressor NCoR1, and prosurvival factor Bcl-2, and Akt and evaluation of Akt phosphorylation levels.

RESULTS

Compared with the control group, UPA does not alter PR protein levels or expression patterns in myomas, and the PR-A/PR-B ratio was similar, as well as cytoplasmic or nuclear expression of cofactors SRC1 and NCoR1. Bcl-2 was heterogeneously expressed throughout the samples and no significant modification in expression was evidenced. No significant difference was found in Akt expression and phosphorylation between treated and untreated myomas.

CONCLUSION

This study did not find any significant change in the expression of the studied factors in myomas after UPA exposure. In conclusion, various theories on myomas cells proposed on the basis of in vitro studies are not supported in vivo.

Novel Non-steroidal Progesterone Receptor Ligands Based on m-Carborane Containing a Secondary Alcohol: Effect of Chirality on Ligand Activity

The progesterone receptor (PR) controls various physiological processes, including the female reproductive system, and nonsteroidal PR ligands are considered to be drug candidates for treatment of various diseases without significant adverse effects. Here, we designed and synthesized m-carborane-based secondary alcohols and investigated their PR-ligand activity. All the synthesized alcohols exhibited PR-antagonistic activity at subnanomolar concentration. Among them, alcohols having a small alkyl side chain and a 4-cyanophenyl group also exhibited PR-agonistic activity in a relatively high concentration range. Optical resolution of secondary alcohols having a methyl side chain was performed, and the PR-ligand activity and PR-binding affinity of the purified enantiomers were examined. The chirality of the secondary alcohol appears to have a more significant influence on PR-agonistic activity than on antagonistic activity.

Human Chorionic Gonadotrophin as a Possible Mediator of Leiomyoma Growth during Pregnancy: Molecular Mechanisms

Uterine fibroids are the most common gynecologic benign tumors. Studies supporting a strong pregnancy-related growth of leiomyomas generally claimed a crucial role of sex steroid hormones. However, sex steroids are unlikely the unique actors involved as estrogen and progesterone achieve a pick serum concentration in the last trimester while leiomyomas show a typical increase during the first trimester. Given the rapid exponential raise in serum human Chorionic Gonadotrophin (hCG) at the beginning of gestation, we conducted a review to assess the potential role of hCG in the striking growth of leiomyomas during initial pregnancy. Fibroid growth during initial pregnancy seems to correlate to the similar increase of serum hCG levels until 12 weeks of gestation. The presence of functional Luteinizing Hormone/human Chorionic Gonadotropin (LH/hCG) receptors was demonstrated on leiomyomas. In vitro treatment of leiomyoma cells with hCG determines an up to 500% increase in cell number after three days. Expression of cyclin E and cyclin-dependent kinase 1 was significantly increased in leiomyoma cells by hCG treatment. Moreover, upon binding to the receptor, hCG stimulates prolactin secretion in leiomyoma cells, promoting cell proliferation via the mitogen-activated protein kinase cascade. Fibroid enlargement during initial pregnancy may be regulated by serum hCG.

Different dosages of mifepristone versus enantone to treat uterine fibroids: A multicenter randomized controlled trial

BACKGROUND

To evaluate the efficacy and safety of 10 mg and 25 mg mifepristone per day compared with 3.75 mg enantone in treating uterine fibroids.

METHODS

This is a Multicenter randomized controlled trial. A total of 501 subjects with symptomatic uterine fibroids were enrolled and randomized into the group of 10mg, 25mg mifepristone and 3.75 enantone (with 307, 102 and 92 subjects respectively), with 458 subjects completed the treatment. Three months of daily therapy with oral mifepristone (at a dose of either 10 mg or 25 mg) or once-monthly subcutaneous injections of enantone (at a dose of 3.75 mg) were used. Change in volume of the largest uterine fibroid was the primary efficacy variable, and secondary efficacy variables included changes in anemia and relevant symptom. Safety evaluation included the analyses of adverse events, laboratory values, and relevant endometrial changes.

RESULTS

After three months of treatment, the mean volume of the largest leiomyoma was significantly reduced by mifepristone 10 mg or 25 mg or enantone 3.75 mg (40.27%, 42.59% and 44.49% respectively) (P < 0.0001). Percentage change from baseline in largest leiomyoma volume was not statistically significant among the three groups (P = 0.1057). Most of the patients in all groups experienced amenorrhea after the treatment. There were also significant elevations in red blood cell count, hemoglobin and hematocrit (P < 0.0001), and significant reductions in prevalence of dysmenorrhea, pelvic pressure, non-menstrual abdominal pain (P < 0.0001) in each group, while no significant difference among the three groups.All study medications are well-tolerated, and no serious adverse event was reported. Treatment-related adverse event rate was significantly lower in mifepristone 10 mg group, compared to Enantone 3.75 mg group (13.59% vs. 32.58%, P = 0.0002). In both mifepristone groups, estradiol levels were maintained in the premenopausal range, whereas patients in the enantone group had a significant reduction to postmenopausal levels (P < 0.0001).

CONCLUSION

10mg is as effective as 25mg mifepristone and 3.75 mg enantone with minimal drug-related side effects, and may provide an alternative for clinical application, especially for patient who are in perimenopause with uterine fibroids.

Efficacy of Use of Long-Term, Low-Dose Mifepristone for the Treatment of Fibroids

BACKGROUND

Fibroid or myoma is the commonest reported tumor of uterus, and is one of the important reasons for hysterectomy in our setting. Different drugs are available for medical management of fibroid uterus including mifepristone, a progesterone antagonist. Varying dosage regimen for mifepristone was studied as medical management of fibroid uterus. The aim of the project was to study the effect of mifepristone on the symptoms and size of fibroids, especially using a low-dose regimen for 6 months. In addition, any symptomatic improvement of menorrhagia and dysmenorrhea was also studied.

METHODS

The study was designed as an observational prospective "before-after" study. Women diagnosed with uterine fibroids attending OPD of a tertiary care hospital were selected according to the inclusion criteria. A total of 36 patients were enrolled in the study. Sample size was calculated to study changes in various parameters after 6 months treatment with mifepristone 50 mg once a week. Baseline investigations were performed and menstrual blood loss was assessed using pictorial blood assessment charts. Fifty milligrams of mifepristone weekly was used, and patient assessed at 1 and 6 month. They were also further followed up till 3 months after stopping the drug to observe the changes in menstrual pattern, fibroid volume, hemoglobin and liver function tests. Baseline endometrial biopsy and another at 6 month on cessation of drug therapy were done for all patients.

RESULTS

Majority of the study population comprised of perimenopausal women, i.e., 41-45 years (44 %). Fifty percent of the patients were Para 2 and belonged to the perimenopausal age-group (18 out of 36). The dominant presenting symptom was menorrhagia associated with dysmenorrhea and pelvic pain. After 6 months of treatment with mifepristone, the mean fibroid volume reduced from 204.33 to 113.16 cm(3) (n = 33); p ≤ 0.001, and the percentage mean volume reduction of the fibroid in the study population was 44.57 % (range 1.10-100 %). Immediate reduction in bleeding PV was observed in 100 %, and 88.89 % (32/36) patients attained amenorrhea. The mean hemoglobin increased from 9.18 to 10.82 g/dl (p = 0.001). There was a transient rise in mean transaminases (AST/ALT) levels at 6 months which reverted to normal at 9 months follow-up.

CONCLUSION

To conclude, 6 months therapy with 50 mg of mifepristone given weekly is efficacious and acceptable for the treatment of symptomatic leiomyoma, especially in a select group of patients. Although its use as a primary medical therapy is limited due to recurrence of fibroid after stopping treatment, it is useful for perimenopausal women whose myoma would regress after menopause, and younger infertile patients with small-size deep intramural myomas not easily accessible to either hysteroscopic or laparoscopic surgery. It is also beneficial as a preoperative adjunct, in patients with preoperative severe anemia and large fibroids where surgery is technically difficult. Mode of surgery can be changed to a less-invasive vaginal hysterectomy rather than an abdominal procedure.

Epidemiological and genetic clues for molecular mechanisms involved in uterine leiomyoma development and growth

BACKGROUND

Uterine leiomyomas (fibroids) are highly prevalent benign smooth muscle tumors of the uterus. In the USA, the lifetime risk for women developing uterine leiomyomas is estimated as up to 75%. Except for hysterectomy, most therapies or treatments often provide only partial or temporary relief and are not successful in every patient. There is a clear racial disparity in the disease; African-American women are estimated to be three times more likely to develop uterine leiomyomas and generally develop more severe symptoms. There is also familial clustering between first-degree relatives and twins, and multiple inherited syndromes in which fibroid development occurs. Leiomyomas have been described as clonal and hormonally regulated, but despite the healthcare burden imposed by the disease, the etiology of uterine leiomyomas remains largely unknown. The mechanisms involved in their growth are also essentially unknown, which has contributed to the slow progress in development of effective treatment options.

METHODS

A comprehensive PubMed search for and critical assessment of articles related to the epidemiological, biological and genetic clues for uterine leiomyoma development was performed. The individual functions of some of the best candidate genes are explained to provide more insight into their biological function and to interconnect and organize genes and pathways in one overarching figure that represents the current state of knowledge about uterine leiomyoma development and growth.

RESULTS

In this review, the widely recognized roles of estrogen and progesterone in uterine leiomyoma pathobiology on the basis of clinical and experimental data are presented. This is followed by fundamental aspects and concepts including the possible cellular origin of uterine fibroids. The central themes in the subsequent parts are cytogenetic aberrations in leiomyomas and the racial/ethnic disparities in uterine fibroid biology. Then, the attributes of various in vitro and in vivo, human syndrome, rodent xenograft, naturally mutant, and genetically modified models used to study possible molecular mechanisms of leiomyoma development and growth are described. Particular emphasis is placed on known links to fibrosis, hypertrophy, and hyperplasia and genes that are potentially important in these processes.

CONCLUSIONS

Menstrual cycle-related injury and repair and coinciding hormonal cycling appears to affect myometrial stem cells that, at a certain stage of fibroid development, often obtain cytogenetic aberrations and mutations of Mediator complex subunit 12 (MED12). Mammalian target of rapamycin (mTOR), a master regulator of proliferation, is activated in many of these tumors, possibly by mechanisms that are similar to some human fibrosis syndromes and/or by mutation of upstream tumor suppressor genes. Animal models of the disease support some of these dysregulated pathways in fibroid etiology or pathogenesis, but none are definitive. All of this suggests that there are likely several key mechanisms involved in the disease that, in addition to increasing the complexity of uterine fibroid pathobiology, offer possible approaches for patient-specific therapies. A final model that incorporates many of these reported mechanisms is presented with a discussion of their implications for leiomyoma clinical practice.

Role of nuclear progesterone receptor isoforms in uterine pathophysiology

BACKGROUND

Progesterone is a key hormonal regulator of the female reproductive system. It plays a major role to prepare the uterus for implantation and in the establishment and maintenance of pregnancy. Actions of progesterone on the uterine tissues (endometrium, myometrium and cervix) are mediated by the combined effects of two progesterone receptor (PR) isoforms, designated PR-A and PR-B. Both receptors function primarily as ligand-activated transcription factors. Progesterone action on the uterine tissues is qualitatively and quantitatively determined by the relative levels and transcriptional activities of PR-A and PR-B. The transcriptional activity of the PR isoforms is affected by specific transcriptional coregulators and by PR post-translational modifications that affect gene promoter targeting. In this context, appropriate temporal and cell-specific expression and function of PR-A and PR-B are critical for normal uterine function.

METHODS

Relevant studies describing the role of PRs in uterine physiology and pathology (endometriosis, uterine leiomyoma, endometrial cancer, cervical cancer and recurrent pregnancy loss) were comprehensively searched using PubMed, Cochrane Library, Web of Science, and Google Scholar and critically reviewed.

RESULTS

Progesterone, acting through PR-A and PR-B, regulates the development and function of the endometrium and induces changes in cells essential for implantation and the establishment and maintenance of pregnancy. During pregnancy, progesterone via the PRs promotes myometrial relaxation and cervical closure. Withdrawal of PR-mediated progesterone signaling triggers menstruation and parturition. PR-mediated progesterone signaling is anti-mitogenic in endometrial epithelial cells, and as such, mitigates the tropic effects of estrogen on eutopic normal endometrium, and on ectopic implants in endometriosis. Similarly, ligand-activated PRs function as tumor suppressors in endometrial cancer cells through inhibition of key cellular signaling pathways required for growth. In contrast, progesterone via PR activation appears to increase leiomyoma growth. The exact role of PRs in cervical cancer is unclear. PRs regulate implantation and therefore aberrant PR function may be implicated in recurrent pregnancy loss (RPL). PRs likely regulate key immunogenic factors involved in RPL. However, the exact role of PRs in the pathophysiology of RPL and the use of progesterone for therapeutic benefit remains uncertain.

CONCLUSIONS

PRs are key mediators of progesterone action in uterine tissues and are essential for normal uterine function. Aberrant PR function (due to abnormal expression and/or function) is a major cause of uterine pathophysiology. Further investigation of the underlying mechanisms of PR isoform action in the uterus is required, as this knowledge will afford the opportunity to create progestin/PR-based therapeutics to treat various uterine pathologies.

Antiprogestins in gynecological diseases

Antiprogestins constitute a group of compounds, developed since the early 1980s, that bind progesterone receptors with different affinities. The first clinical uses for antiprogestins were in reproductive medicine, e.g., menstrual regulation, emergency contraception, and termination of early pregnancies. These initial applications, however, belied the capacity for these compounds to interfere with cell growth. Within the context of gynecological diseases, antiprogestins can block the growth of and kill gynecological-related cancer cells, such as those originating in the breast, ovary, endometrium, and cervix. They can also interrupt the excessive growth of cells giving rise to benign gynecological diseases such as endometriosis and leiomyomata (uterine fibroids). In this article, we present a review of the literature providing support for the antigrowth activity that antiprogestins impose on cells in various gynecological diseases. We also provide a summary of the cellular and molecular mechanisms reported for these compounds that lead to cell growth inhibition and death. The preclinical knowledge gained during the past few years provides robust evidence to encourage the use of antiprogestins in order to alleviate the burden of gynecological diseases, either as monotherapies or as adjuvants of other therapies with the perspective of allowing for long-term treatments with tolerable side effects. The key to the clinical success of antiprogestins in this field probably lies in selecting those patients who will benefit from this therapy. This can be achieved by defining the genetic makeup required - within each particular gynecological disease - for attaining an objective response to antiprogestin-driven growth inhibition therapy.Free Spanish abstractA Spanish translation of this abstract is freely available at http://www.reproduction-online.org/content/149/1/15/suppl/DC1.

Ovarian steroids, stem cells and uterine leiomyoma: therapeutic implications

BACKGROUND

Uterine leiomyoma is the most common benign tumor in women and is thought to arise from the clonal expansion of a single myometrial smooth muscle cell transformed by a cellular insult. Leiomyomas cause a variety of symptoms, including abnormal uterine bleeding, pelvic pain, bladder or bowel dysfunction, and recurrent pregnancy loss, and are the most common indication for hysterectomy in the USA. A slow rate of cell proliferation, combined with the production of copious amounts of extracellular matrix, accounts for tumor expansion. A common salient feature of leiomyomas is their responsiveness to steroid hormones, thus providing an opportunity for intervention.

METHODS

A comprehensive search of PUBMED was conducted to identify peer-reviewed literature published since 1980 pertinent to the roles of steroid hormones and somatic stem cells in leiomyoma, including literature on therapeutics that target steroid hormone action in leiomyoma. Reviewed articles were restricted to English language only. Studies in both animals and humans were reviewed for the manuscript.

RESULTS

Estrogen stimulates the growth of leiomyomas, which are exposed to this hormone not only through ovarian steroidogenesis, but also through local conversion of androgens by aromatase within the tumors themselves. The primary action of estrogen, together with its receptor estrogen receptor α (ERα), is likely mediated via induction of progesterone receptor (PR) expression, thereby allowing leiomyoma responsiveness to progesterone. Progesterone has been shown to stimulate the growth of leiomyoma through a set of key genes that regulate both apoptosis and proliferation. Given these findings, aromatase inhibitors and antiprogestins have been developed for the treatment of leiomyoma, but neither treatment results in complete regression of leiomyoma, and tumors recur after treatment is stopped. Recently, distinct cell populations were discovered in leiomyomas; a small population showed stem-progenitor cell properties, and was found to be essential for ovarian steroid-dependent growth of leiomyomas. Interestingly, these stem-progenitor cells were deficient in ERα and PR and instead relied on the strikingly higher levels of these receptors in surrounding differentiated cells to mediate estrogen and progesterone action via paracrine signaling.

CONCLUSIONS

It has been well established that estrogen and progesterone are involved in the proliferation and maintenance of uterine leiomyoma, and the majority of medical treatments currently available for leiomyoma work by inhibiting steroid hormone production or action. A pitfall of these therapeutics is that they decrease leiomyoma size, but do not completely eradicate them, and tumors tend to regrow once treatment is stopped. The recent discovery of stem cells and their paracrine interactions with more differentiated cell populations within leiomyoma has the potential to provide the missing link between developing therapeutics that temper leiomyoma growth and those that eradicate them.

Expression of a mitochondrial progesterone receptor (PR-M) in leiomyomata and association with increased mitochondrial membrane potential

CONTEXT

Clinical evidence supports a role for progestins in the growth of leiomyomata (fibroids). The mechanism(s) for this is thought to involve gene regulation via the nuclear progesterone receptors. Recently a mitochondrial progesterone receptor (PR-M) has been identified with evidence of a progesterone/progestin-dependent increase in cellular respiration. This observation raises a possible new mechanism whereby progesterone/progestin may affect the growth of fibroids.

OBJECTIVE

The goals of this research were to determine differential expression of PR-M in normal myometrium compared with the edge of a fibroid within the same uterus, to demonstrate a progestin-dependent increase in mitochondria membrane potential using an immortalized human myometrial cell line and to examine mitochondrial membrane potential in transfected cells expressing the complete coding sequence of PR-M.

DESIGN

Protein levels of PR-M, PR-B, PR-A, mitochondrial porin, and glyceraldehyde-3-phosphate dehydrogenase were determined in the myometrium and adjacent edge of a fibroid in 10 subjects undergoing hysterectomy for benign indications. Mitochondrial membrane potential was determined by fluorescent emission of 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolecarbocyanide iodine in hTERT-HM cells treated with R5020 and in transfected hTERT-HM cells determined by the fluorescent emission of tetramethylrhodamine methyl ester.

RESULTS

Higher levels of PR-M and mitochondrial porin were found in the fibroid edge compared with adjacent myometrium. Progestin increased mitochondrial membrane potential in hTERT-HM cells, which was not affected by a translation inhibitor. This effect was exaggerated in hTERT-HM cells expressing PR-M after transient transfection.

CONCLUSION

These studies suggest a mechanism whereby progesterone/progestin may affect the growth of fibroids by altering mitochondrial activity.

Progesterone action in endometrial cancer, endometriosis, uterine fibroids, and breast cancer

Progesterone receptor (PR) mediates the actions of the ovarian steroid progesterone, which together with estradiol regulates gonadotropin secretion, prepares the endometrium for implantation, maintains pregnancy, and differentiates breast tissue. Separation of estrogen and progesterone actions in hormone-responsive tissues remains a challenge. Pathologies of the uterus and breast, including endometrial cancer, endometriosis, uterine fibroids, and breast cancer, are highly associated with estrogen, considered to be the mitogenic factor. Emerging evidence supports distinct roles of progesterone and its influence on the pathogenesis of these diseases. Progesterone antagonizes estrogen-driven growth in the endometrium, and insufficient progesterone action strikingly increases the risk of endometrial cancer. In endometriosis, eutopic and ectopic tissues do not respond sufficiently to progesterone and are considered to be progesterone-resistant, which contributes to proliferation and survival. In uterine fibroids, progesterone promotes growth by increasing proliferation, cellular hypertrophy, and deposition of extracellular matrix. In normal mammary tissue and breast cancer, progesterone is pro-proliferative and carcinogenic. A key difference between these tissues that could explain the diverse effects of progesterone is the paracrine interactions of PR-expressing stroma and epithelium. Normal endometrium is a mucosa containing large quantities of distinct stromal cells with abundant PR, which influences epithelial cell proliferation and differentiation and protects against carcinogenic transformation. In contrast, the primary target cells of progesterone in the breast and fibroids are the mammary epithelial cells and the leiomyoma cells, which lack specifically organized stromal components with significant PR expression. This review provides a unifying perspective for the diverse effects of progesterone across human tissues and diseases.

The role of progesterone signaling in the pathogenesis of uterine leiomyoma

Uterine leiomyomas are benign tumors that originate from the myometrium. Evidence points to ovarian steroid hormones, in particular, progesterone as major promoters of leiomyoma development and growth. While progesterone action in leiomyomas involves the classical nuclear receptor effects on gene regulation, there is growing evidence that signaling pathways are directly activated by the progesterone receptor (PR) and that PR can interact with growth factor signaling systems to promote proliferation and survival of leiomyomas. Studies investigating the genomic and non-genomic actions of PR and its role in leiomyoma growth are summarized here. Studies testing various selective progesterone receptor modulators for the treatment of leiomyomas are also highlighted. An increased understanding of the mechanisms associated with progesterone-driven growth of leiomyomas is critical in order to develop more efficient and targeted therapies for this prevalent disease.

Mifepristone 2.5 mg versus 5 mg daily in the treatment of leiomyoma before surgery

OBJECTIVES

To evaluate the efficacy and safety of 2.5 mg and 5 mg mifepristone during 3 months for the treatment of uterine fibroids before surgery.

DESIGN

Multicenter randomized clinical trial.

LOCATIONS

Eusebio Hernández Hospital, Havana, Cuba and the Alemán Hospital, Managua, Nicaragua.

SUBJECTS

Included in the study were 146 women with symptomatic uterine fibroids.

TREATMENT

GROUP I: half a tablet of 5 mg (2.5 mg) mifepristone taken orally every 24 hours, and Group II: one tablet of 5 mg mifepristone taken orally every 24 hours over a period of 3 months in both groups. Two endometrial biopsies were performed. VARIABLES TO EVALUATE EFFICACY: Increase in average hemoglobin, changes in fibroid and uterine volume, and symptomatic improvement.

RESULTS

The average hemoglobin at the end of treatment was 0.6 g/dL greater in the 5 mg mifepristone group (P = 0.033). In both groups there were similar reductions in fibroid volumes. Clinical improvement was more significant in the 5 mg group.

CONCLUSION

The dose to be used should be 5 mg.

Genome-wide progesterone receptor binding: cell type-specific and shared mechanisms in T47D breast cancer cells and primary leiomyoma cells

Background

Progesterone, via its nuclear receptor (PR), exerts an overall tumorigenic effect on both uterine fibroid (leiomyoma) and breast cancer tissues, whereas the antiprogestin RU486 inhibits growth of these tissues through an unknown mechanism. Here, we determined the interaction between common or cell-specific genome-wide binding sites of PR and mRNA expression in RU486-treated uterine leiomyoma and breast cancer cells.

Principal Findings

ChIP-sequencing revealed 31,457 and 7,034 PR-binding sites in breast cancer and uterine leiomyoma cells, respectively; 1,035 sites overlapped in both cell types. Based on the chromatin-PR interaction in both cell types, we statistically refined the consensus progesterone response element to G•ACA• • •TGT•C. We identified two striking differences between uterine leiomyoma and breast cancer cells. First, the cis-regulatory elements for HSF, TEF-1, and C/EBPα and β were statistically enriched at genomic RU486/PR-targets in uterine leiomyoma, whereas E2F, FOXO1, FOXA1, and FOXF sites were preferentially enriched in breast cancer cells. Second, 51.5% of RU486-regulated genes in breast cancer cells but only 6.6% of RU486-regulated genes in uterine leiomyoma cells contained a PR-binding site within 5 kb from their transcription start sites (TSSs), whereas 75.4% of RU486-regulated genes contained a PR-binding site farther than 50 kb from their TSSs in uterine leiomyoma cells. RU486 regulated only seven mRNAs in both cell types. Among these, adipophilin (PLIN2), a pro-differentiation gene, was induced via RU486 and PR via the same regulatory region in both cell types.

Conclusions

Our studies have identified molecular components in a RU486/PR-controlled gene network involved in the regulation of cell growth, cell migration, and extracellular matrix function. Tissue-specific and common patterns of genome-wide PR binding and gene regulation may determine the therapeutic effects of antiprogestins in uterine fibroids and breast cancer.

A study evaluating the effect of mifepristone (RU-486) for the treatment of leiomyomata uteri

BACKGROUND

To estimate the efficacy of daily administration of 25 mg mifepristone for the treatment of uterine leiomyoma.

MATERIALS AND METHODS

A total of 30 women were to receive 25 mg mifepristone daily for a period of 6 months. Abdominal ultrasonography was performed before treatment, at 3 months and after 6 months, to evaluate the leiomyoma size and uterine volume. Endometrial biopsy was done after the treatment. Efficacy was estimated by the reduction in leiomyoma size, uterine volume, and improvement in quality of life.

RESULTS

After 180 days of treatment, there was a 47% decrease in the leiomyoma volume and a 53% decrease in the uterine volume. Symptomatic improvement was noted. Twenty-three of 30 women (75.7%) became amenorrheic after the treatment. Endometrial biopsy after treatment revealed simple hyperplasia in two of 30 women.

CONCLUSION

25 mg mifepristone produces reduction in leiomyoma size and uterine volume and produces symptomatic improvement in women with fibroids.

Multiple solitary leiomyomas in the esophagus: report of a case

We herein report our findings for an asymptomatic 65-year-old man presenting with multiple solitary leiomyomas in the esophagus, who was undergoing follow-up for primary aldosteronism with high levels of serum progesterone. Esophageal endoscopy and computed tomography showed multiple submucosal tumors with calcification in the thoracic esophagus. A subtotal esophagectomy was performed because the possibility of malignancy could not be ruled out based on a needle biopsy taken of the specimen. The final resected specimen showed eight solitary, encapsulated nodules between the middle and lower thoracic esophagus. Histopathological examinations showed these nodules to have the typical histological findings of leiomyomas. In addition, staining with antibodies against the progesterone receptor revealed diffuse expression in the nuclei of the leiomyoma cells. Only four cases with more than eight solitary leiomyomas have been reported, including the current case. However, this is the first reported case where primary aldosteronism with elevated serum progesterone levels has been implicated in the pathogenesis of multiple solitary leiomyomas in the esophagus.

Progesterone and mifepristone regulate L-type amino acid transporter 2 and 4F2 heavy chain expression in uterine leiomyoma cells

CONTEXT

Progesterone and its receptor (PR) play key roles in uterine leiomyoma growth. Previously, using chromatin immunoprecipitation-based cloning, we uncovered L-type amino acid transporter 2 (LAT2) as a novel PR target gene. LAT2 forms heterodimeric complexes with 4F2 heavy chain (4F2hc), a single transmembrane domain protein essential for LAT2 to exert its function in the plasma membrane. Until now, little is known about the roles of LAT2/4F2hc in the regulation of the growth of human uterine leiomyoma.

OBJECTIVE

The aim of the study is to investigate the regulation of LAT2 and 4F2hc by progesterone and the antiprogestin mifepristone and their functions in primary human uterine leiomyoma smooth muscle (LSM) cells and tissues from 39 premenopausal women.

RESULTS

In primary LSM cells, progesterone significantly induced LAT2 mRNA levels, and this was blocked by cotreatment with mifepristone. Progesterone did not alter 4F2hc mRNA levels, whereas mifepristone significantly induced 4F2hc mRNA expression. Small interfering RNA knockdown of LAT2 or 4F2hc markedly increased LSM cell proliferation. LAT2, PR-B, and PR-A levels were significantly higher in freshly isolated LSM cells vs. adjacent myometrial cells. In vivo, mRNA levels of LAT2 and PR but not 4F2hc were significantly higher in leiomyoma tissues compared with matched myometrial tissues.

CONCLUSION

We present evidence that progesterone and its antagonist mifepristone regulate the amino acid transporter system LAT2/4F2hc in leiomyoma tissues and cells. Our findings suggest that products of the LAT2/4F2hc genes may play important roles in leiomyoma cell proliferation. We speculate that critical ratios of LAT2 to 4F2hc regulate leiomyoma growth.

Estradiol and progesterone-induced slowing of gonadotropin-releasing hormone pulse frequency is not reversed by subsequent administration of mifepristone

Subsequent to suppression of LH (GnRH) pulse frequency by progesterone (P) and estradiol (E(2)), LH pulse frequency remains slow for 7 days after P withdrawal if mid-luteal E(2) concentrations are maintained. This may reflect an ability of E(2) to potentiate the suppressive effects of low P levels. We explored this notion in a similar experimental paradigm by administering a P-receptor antagonist (mifepristone) after P withdrawal while continuing E(2). Studies were performed in seven ovulatory, non-obese women. Transdermal E(2) (0.2 mg/day) and oral micronized P (100 mg every 8 h) were started within 24 h of the LH surge and continued for 10 days. Subjects then underwent a 13-h blood sampling protocol for determination of LH pulse characteristics and various hormone concentrations. Oral P was then discontinued, and oral mifepristone (50, 100, or 200 mg daily) and transdermal E(2) (0.2 mg/day) were administered for 7 days, after which the above sampling protocol was repeated. Results with all mifepristone doses were similar and therefore pooled. Mean LH, LH amplitude, and mean FSH markedly decreased after 7 days of mifepristone, but LH pulse frequency did not change (3.3 +/- 1.5 vs. 2.4 +/- 1.5 pulses/13 h). Prolactin and androstenedione increased between the first and second admissions, with no changes in E(2), cortisol, testosterone, or DHEAS. In conclusion, blockade of P action by mifepristone does not reverse a suppressed LH pulse frequency within 7 days when E(2) concentrations are maintained, suggesting that P withdrawal alone may not explain the luteal-follicular increase of GnRH pulse frequency.

Estrogen and progesterone receptors: from molecular structures to clinical targets

Research involving estrogen and progesterone receptors (ER and PR) have greatly contributed to our understanding of cell signaling and transcriptional regulation. In addition to the classical ER and PR nuclear actions, new signaling pathways have recently been identified due to ER and PR association with cell membranes and signal transduction proteins. Bio-informatics has unveiled how ER and PR recognize their ligands, selective modulators and co-factors, which has helped to implement them as key targets in the treatment of benign and malignant tumors. Knowledge regarding ER and PR is vast and complex; therefore, this review will focus on their isoforms, signaling pathways, co-activators and co-repressors, which lead to target gene regulation. Moreover it will highlight ER and PR involvement in benign and malignant diseases as well as pharmacological substances influencing cell signaling and provide established and new structural insights into the mechanism of activation and inhibition of these receptors.

Antiprogestin pharmacodynamics, pharmacokinetics, and metabolism: implications for their long-term use

Antiprogestins represent a relatively new and promising class of therapeutic agents that could have significant impact on human health and reproduction. In the present work, the pharmacodynamics, pharmacokinetics, and metabolism of mifepristone (MIF), lilopristone (LIL), and onapristone (ONA) in humans are reviewed, and characteristics bearing important clinical implications are discussed. Although MIF has gained notoriety as an "abortion pill," antiprogestins may more importantly prove effective in the treatment of endometriosis, uterine leiomyoma, meningioma, cancers of the breast and prostate, and as contraceptive agents. MIF pharmacokinetics display nonlinearities associated with saturable plasma protein (alpha 1-acid glycoprotein, AAG) binding and characterized by lack of dose dependency for parent drug plasma concentrations (for doses greater than 100 mg) and a zero-order phase of elimination. LIL and ONA pharmacokinetics are less well characterized but ONA does not appear to bind AAG and displays a much shorter t1/2 than the other agents. The three antiprogestins are substrates of cytochrome P450 (CYP) 3A4, an enzyme exceedingly important in human xenobiotic metabolism. Even more implicative of likely drug-drug interactions subsequent to their long-term administration are recent data from our laboratory indicating that they inactivate CYP3A4 in a cofactor- and time-dependent manner, suggesting that complexation and induction of the enzyme may occur in vivo via protein stabilization. Moreover, it has been demonstrated that MIF increases CYP3A4 mRNA levels in human hepatocytes in primary culture, indicative of message stabilization and/or transcriptional activation of CYP3A4 expression. Finally, MIF has also been shown to inhibit P-glycoprotein function. Whether LIL and ONA share these latter two characteristics with MIF has not yet been determined but they illustrate properties that, in addition to diminished antiglucocorticoid activities and altered pharmacokinetic characteristics, warrant consideration during the development of these and never antiprogestational agents.

Antioxidant: a new role for RU-486 and related compounds

RU-486 (17 beta-hydroxy-4-dimethylaminophenyl-17-alpha-propenyl estrone 4,9 diene-3-one; mifepristone) is suggested to act by binding to progesterone and glucocorticoid receptors. Based on its chemical nature, we anticipated that RU-486 may have potent antioxidant properties. We used the oxidation of LDL as our model system. RU-486 and a similar compound, onapristone, at 1-5-microM concentrations, decreased the formation of oxidized LDL. LDL isolated from plasma of subjects who were orally supplemented with RU-486 was resistant to oxidation, as compared to LDL isolated from control plasma. The antioxidant effect of RU-486 appears to reside in the dimethylaminophenyl side chain moiety. Reduction of the A-ring of the steroid molecule had no effect on its antioxidant property. Analogs of RU-486 which lack the dimethylaminophenyl group, were without antioxidant activity. Levonorgestrel, which lacks the dimethylaminophenyl group failed to inhibit the oxidation of LDL even at 100-microM levels. In contrast, ethinylestradiol and estradiol which do not possess the dimethylamino group, were able to inhibit the oxidation of LDL by virtue of their phenolic steroid "A" ring. Thus RU-486, with its long half life, high plasma concentrations, association with lipoproteins, and ability to readily enter the cell may have additional intra- and extra-cellular antioxidant effects.