Therapeutic Roles of Statins in Gynecology and Obstetrics: The Current Evidence

Use of statins and risks of ovarian, uterine, and cervical diseases: a cohort study in the UK Biobank

PURPOSE

To examine the associations between use of statins and risks of various ovarian, uterine, and cervical diseases, including ovarian cancer, endometrial cancer, cervical cancer, ovarian cyst, polycystic ovarian syndrome, endometriosis, endometrial hyperplasia, endometrial polyp, and cervical polyp.

METHODS

We conducted a cohort study among female participants in the UK Biobank. Information on the use of statins was collected through verbal interview. Outcome information was obtained by linking to national cancer registry data and hospital inpatient data. We used Cox proportional hazards regression to examine the associations.

RESULTS

A total of 180,855 female participants (18,403 statin users and 162,452 non-users) were included. Use of statins was significantly associated with increased risks of cervical cancer (adjusted hazard ratio (HR), 1.55; 95% confidence interval (95% CI), 1.05-2.30) and polycystic ovarian syndrome (adjusted HR, 4.39; 95% CI, 1.68-11.49). However, we observed no significant association between use of statins and risk of ovarian cancer, endometrial cancer, ovarian cyst, endometriosis, endometrial hyperplasia, endometrial polyp, or cervical polyp.

CONCLUSION

Our findings suggest that use of statins is associated with increased risks of cervical cancer and polycystic ovarian syndrome, but is not associated with increased or decreased risk of ovarian cancer, endometrial cancer, ovarian cyst, endometriosis, endometrial polyp, or cervical polyp.

Currently Available Treatment Modalities for Uterine Fibroids

Uterine fibroids (leiomyomas and myomas) are the most common benign gynecological condition in patients presenting with abnormal uterine bleeding, pelvic masses causing pressure or pain, infertility and obstetric complications. Almost a third of women with fibroids need treatment due to symptoms.

OBJECTIVES

In this review we present all currently available treatment modalities for uterine fibroids.

METHODS

An extensive search for the available data regarding surgical, medical and other treatment options for uterine fibroids was conducted.

REVIEW

Nowadays, treatment for fibroids is intended to control symptoms while preserving future fertility. The choice of treatment depends on the patient's age and fertility and the number, size and location of the fibroids. Current management strategies mainly involve surgical interventions (hysterectomy and myomectomy hysteroscopy, laparoscopy or laparotomy). Other surgical and non-surgical minimally invasive techniques include interventions performed under radiologic or ultrasound guidance (uterine artery embolization and occlusion, myolysis, magnetic resonance-guided focused ultrasound surgery, radiofrequency ablation of fibroids and endometrial ablation). Medical treatment options for fibroids are still restricted and available medications (progestogens, combined oral contraceptives andgonadotropin-releasing hormone agonists and antagonists) are generally used for short-term treatment of fibroid-induced bleeding. Recently, it was shown that SPRMs could be administered intermittently long-term with good results on bleeding and fibroid size reduction. Novel medical treatments are still under investigation but with promising results.

CONCLUSIONS

Treatment of fibroids must be individualized based on the presence and severity of symptoms and the patient's desire for definitive treatment or fertility preservation.

Atorvastatin exerts dual effects of lesion regression and ovarian protection in the prevention and treatment of endometriosis

Endometriosis is a frequent, chronic, estrogen-dependent and inflammatory gynecological disease leading to pain and infertility. Clinical and metabolic studies reveal that patients with endometriosis are susceptible to hyperlipemia and lipid dysfunction, putting them at ascending risk of cardiovascular diseases. Statins constitute a group of cholesterol-lowering drugs with pleiotropic effects. A plethora of researches have proved their ability to inhibit the growth of ectopic lesions in endometriosis. However, concerns exist about their possible adverse effects on ovarian function. This study aimed to investigate the possible effect of atorvastatin on the ovarian endocrine function and fertility capacity in the prevention and treatment of endometriosis. Here, 5 mg/kg atorvastatin was intraperitoneally injected to the endometriosis mice once a day for consecutive fourteen days during and after the development of endometriotic implants. The results indicated that atorvastatin not only led to regression of the ectopic lesions, but also caused no discernible harm to the ovary for both the preventive and the therapeutic models. In addition, it elicited a protective effect on the ovarian reserve and fertility possibly by reducing inflammation in the ovary. Hence, atorvastatin could be a promising drug for endometriosis prevention and treatment.

Drug Repositioning for Ovarian Cancer Treatment: An Update

Ovarian cancer (OC) is one of the most prevalent malignancies in female reproductive organs, and its 5-year survival is below 45%. Despite the advances in surgical and chemotherapeutic options, OC treatment is still a challenge, and new anticancer agents are urgently needed. Drug repositioning has gained significant attention in drug discovery, representing a smart way to identify new clinical applications for drugs whose human safety and pharmacokinetics have already been established, with great time and cost savings in pharmaceutical development endeavors. This review offers an update on the most promising drugs repurposable for OC treatment and/or prevention.

Cardiometabolic profile of women with uterine leiomyoma: a cross-sectional study

BACKGROUND

Emerging evidence suggests that cardiometabolic risk factors contribute to uterine leiomyoma development, but cardiometabolic profiles of women with the tumor remain poorly defined. This study aimed to determine the association of cardiometabolic comorbidities and cardiometabolic medication use with a leiomyoma diagnosis.

METHODS

In this cross-sectional study, aggregate-level data from 2013-2020 were collected using the SlicerDicer feature of Epic (Epic, Verona, WI, USA) electronic medical record system. Women ≥18 years with at least one visit or hospital encounter at the Johns Hopkins Health System (N.=679,981) were assigned as cases or controls according to leiomyoma status. Individual prevalence of each prespecified cardiometabolic comorbidity and relevant prescription medications was obtained. Prevalence Odds Ratios were used to assess the association of cardiometabolic comorbidities and medication use with uterine leiomyoma.

RESULTS

Women with uterine leiomyoma (N.=27,703) were more likely to be obese (2.56; 95% CI: 2.49-2.63), have metabolic syndrome (1.82; 95% CI: 1.51-2.19), essential hypertension (1.45; 95% CI: 1.42-1.49), diabetes mellitus (1.29; 95% CI: 1.24-1.33) and hyperlipidemia (1.23; 95% CI: 1.19-1.26). These associations were stronger among younger women and persisted after excluding those with a hysterectomy. Notably, statins were the only medications associated with a lower leiomyoma risk (0.81; 95% CI: 0.79-0.84).

CONCLUSIONS

Uterine leiomyoma is associated with a spectrum of cardiometabolic comorbidities and use of associated medications, constituting an unfavorable cardiometabolic profile in women with the tumor. If definitively correlated, prevention and early management of cardiometabolic risk factors may decrease uterine leiomyoma incidence, and screening women with uterine leiomyoma for cardiometabolic comorbidities may aid in cardiovascular disease prevention.

Simvastatin-loaded liposome nanoparticles treatment for uterine leiomyoma in a patient-derived xenograft mouse model: a pilot study

Uterine leiomyomas are complex tumours with limited medical treatment options. Simvastatin is used to treat hypercholesterolaemia and has shown promising effects as a treatment option for leiomyomas. Previously, our group demonstrated a promising effect of simvastatin treatment in a patient-derived xenograft mouse model. Here, we tested the efficacy of simvastatin liposomal nanoparticles (NPs). After bilateral leiomyoma xenograft implantation, mice (N = 12) were divided into three treatment arms: control, simvastatin and simvastatin-loaded liposome NPs (simvastatin-NPs). Treatment with simvastatin significantly reduced tumour volume and inhibited the Ki67 expression when compared to the control group. There was a trend of reduced tumour volume and Ki67 expression after treatment with simvastatin-NP; however, the results were not significant. Due to low bioavailability and short half-life of simvastatin, liposomal NPs have the potential to enhance drug delivery, however, in this study NP did not provide improvement over simvastatin, but did demonstrate their potential for the delivery of simvastatin.Impact statementWhat is already known on this subject? Simvastatin treatment in a patient-derived xenograft mouse model reduced tumour growth and decreased proliferation.What do the results of this study add? Treatment with simvastatin significantly reduced tumour volume and inhibited the Ki67 expression when compared to the control group. There was a trend of reduced tumour volume and Ki67 expression after treatment with simvastatin-NP, however, it did not improve the efficacy of simvastatin at reducing tumour growth and proliferation.What are the implications of these findings for clinical practice and/or further research? More studies are needed to optimise the formulation of NPs to further enhance the sustainable delivery of simvastatin.

Simvastatin inhibits stem cell proliferation in human leiomyoma via TGF-β3 and Wnt/β-Catenin pathways

Uterine leiomyoma (UL) is the most common gynaecologic tumour, affecting an estimated 70 to 80% of women. Leiomyomas develop from the transformation of myometrial stem cells into leiomyoma stem (or tumour-initiating) cells. These cells undergo self-renewal and differentiation to mature cells, both are necessary for the maintenance of tumour stem cell niche and tumour growth, respectively. Wnt/β-catenin and TGF-β/SMAD pathways, both overactive in UL, promote stem cell self-renewal, crosstalk between stem and mature cells, cellular proliferation, extracellular matrix (ECM) accumulation and drive overall UL growth. Recent evidence suggests that simvastatin, an antihyperlipidemic drug, may have anti-leiomyoma properties. Herein, we investigated the effects of simvastatin on UL stem cells. We isolated leiomyoma stem cells by flow cytometry using DyeCycle Violet staining and Stro-1/CD44 surface markers. We found that simvastatin inhibits proliferation and induces apoptosis in UL stem cells. In addition, it also suppressed the expression of the stemness markers Nanog, Oct4 and Sox2. Simvastatin significantly decreased the production of the key ECM proteins, collagen 1 and fibronectin. Finally, it inhibited genes and/or proteins expression of TGF-β1, 2 and 3, SMAD2, SMAD4, Wnt4, β-Catenin, LRP6, AXIN2 and Cyclin D1 in UL stem cells, all are key drivers of the TGF-β3/SMAD2 and Wnt4/β-Catenin pathways. Thus, we have identified a novel stem cell-targeting anti-leiomyoma simvastatin effect. Further studies are needed to replicate these findings in vivo.

Diet and Nutrition in Gynecological Disorders: A Focus on Clinical Studies

A healthy lifestyle and a balanced diet play a paramount role in promoting and maintaining homeostatic functions and preventing an array of chronic and debilitating diseases. Based upon observational and epidemiological investigations, it is clear that nutritional factors and dietary habits play a significant role in gynecological disease development, including uterine leiomyoma, endometriosis, polycystic ovary syndrome, and gynecological malignancies. Diets rich in fruits and vegetables, Mediterranean diets, green tea, vitamin D, and plant-derived natural compounds may have a long-term positive impact on gynecological diseases, while fats, red meat, alcohol, and coffee may contribute to their development. Data regarding the association between dietary habits and gynecological disorders are, at times, conflicting, with potential confounding factors, including food pollutants, reduced physical activity, ethnic background, and environmental factors limiting overall conclusions. This review provides a synopsis of the current clinical data and biological basis of the association between available dietary and nutritional data, along with their impact on the biology and pathophysiology of different gynecological disorders, as well as an outlook on future directions that will guide further investigational research.

Assessing the risk of rapid fibroid growth in patients with asymptomatic solitary uterine myoma using a multivariate prediction model

Background

Long-term conservative approaches are effective management options for asymptomatic uterine fibroids, but not for uterine myomas with excessive growth. In this investigation, a regression model was constructed to evaluate the clinical characteristics related to uterine fibroids’ growth.

Methods

In this retrospective study, 19,840 patients with ultrasound-diagnosed uterine fibroids were identified from six centers between 2013 and 2019. In total, 739 patients were followed up for more than 1 year with B-ultrasound test results and clinical test results and had no acute events or surgical treatments. The endpoint was changed in the size of the uterine fibroids. Multivariate stepwise logistic regression analysis was used to identify predictors of uterine fibroid growth, and these were used to build a prediction model. The prediction model’s discrimination, calibration, and clinical efficacy were assessed using the area under the curve (AUC)/index of concordance (C-index), calibration plot, decision curve analysis, and clinical impact curve. Internal validation was performed using bootstrapping validation. A linear regression model was constructed to predict uterine fibroids’ growth rate without the occurrence of acute events.

Results

A total of 513 patients presented with significant growth of uterine fibroids, with an average follow-up time of 927 days, and 267 patients showed negative growth, with an average follow-up time of 960 days. Age, follicle-stimulating hormone (FSH), low-density lipoprotein (LDL), luteinizing hormone (LH), total cholesterol (TCHO), and neutrophil to lymphocyte ratio (NLR) were the main influential factors that predicted the uterine fibroid growth state, and these were used to develop a nomogram with predictive accuracy (AUC: 0.825). A linear regression prediction model was built based on the following factors: FSH, high-density lipoprotein (HDL), LH, triglyceride (TRIG), TCHO, and lymphocyte to monocyte ratio (LMR). The mean square error (MSE) was 0.32.

Conclusions

This study directly measured the growth rate of uterine fibroids. A prediction model assessing the growth rate of asymptomatic uterine fibroids was established. This model is useful for the early detection of potentially rapidly growing uterine fibroids in patients.

Small Molecule Targeting of Oxysterol-Binding Protein (OSBP)-Related Protein 4 and OSBP Inhibits Ovarian Cancer Cell Proliferation in Monolayer and Spheroid Cell Models

The development of precision drugs for the selective treatment of ovarian cancer will require targeting proliferative factors selectively expressed in ovarian tumors or targeting unique physiological microenvironments specific for ovarian tumors. Here, we report that oxysterol-binding protein (OSBP)-related protein 4 (ORP4) is a potential druggable precision target in ovarian cancer cells. ORP4 has limited expression in normal tissues and was recently recognized to be a cancer-specific driver of cellular proliferation, including in patient-isolated leukemias. We demonstrate that ORP4 is strongly expressed in a panel of ovarian cancer cell lines. The antiproliferative natural product compound OSW-1 targets ORP4 and OSBP. Our results demonstrate that the OSW-1 compound has high antiproliferative potency in both monolayer and three-dimensional ovarian cancer spheroid models, especially compared to the standard-of-care agents cisplatin and paclitaxel. OSW-1 compound treatment induces a loss of ORP4 expression after 48 h, which is coincident with the cytotoxic effects of OSW-1. The absence of extracellular lipids markedly potentiated the cytotoxicity of OSW-1, which was reversed by addition of extracellular free cholesterol. OSBP, but not ORP4, is reported to transport cholesterol and other lipids between organelles. Our results indicate that the targeting of ORP4 is responsible for the antiproliferative activity of the OSW-1 compound, but that in the absence of exogenously supplied cholesterol, which might be similar to the in vivo ovarian cancer microenvironment, possible OSW-1 targeting of OSBP further potentiates the anticancer activity of the compound. Overall, ORP4 and potentially OSBP are revealed as potential druggable targets for the development of novel treatments for ovarian cancer.

Statins as adjuvants in the treatment of ovarian cancer: Controversy and misunderstanding

Ovarian cancer is frequently detected in advanced stages when the chances of survival are very low. Although chemotherapy is the treatment of choice, it is often rapidly compromised by the development of chemoresistance in patients. There are few pharmacological alternatives for managing chemoresistant ovarian cancer and statins have been suggested as an alternative, but their use is considered controversial. We present an overview of the most relevant epidemiological, in vitro and in vivo studies on the effects of statins in mono- or polytherapy for ovarian cancer. We conclude that the negative or inconclusive results of some epidemiological studies on statin-based cancer treatment are probably due, in large part, to the low doses given to patients, equivalent to those prescribed for hypercholesterolemia. Higher concentrations are well tolerated in animal models and by most patients in clinical trials. Future research is necessary to explore this possibility.

Uterine Stem Cells and Benign Gynecological Disorders: Role in Pathobiology and Therapeutic Implications

Stem cells in the endometrium and myometrium possess an immense regenerative potential which is necessary to maintain the menstrual cycle and support pregnancy. These cells, as well as bone marrow stem cells, have also been implicated in the development of common benign gynecological disorders including leiomyomas, endometriosis and adenomyosis. Current evidence suggests the conversion of uterine stem cells to tumor initiating stem cells in leiomyomas, endometriosis stem cells, and adenomyosis stem cells, acquiring genetic and epigenetic alterations for the progression of each benign condition. In this comprehensive review, we aim to summarize the progress that has been made to characterize the involvement of stem cells in the pathogenesis of benign gynecologic conditions which, despite their enormous burden, are not yet fully understood. We focus on the stem cell characteristics and aberrations that contribute to the development of benign gynecological disorders and the possible clinical implications of what is known so far. Lastly, we discuss the role of uterine stem cells in the setting of regenerative medicine, particularly in the treatment of Asherman syndrome.Graphical abstract.

Simvastatin ameliorates altered mechanotransduction in uterine leiomyoma cells

BACKGROUND

Uterine leiomyomas, the most common tumors of the female reproductive system, are characterized by excessive deposition of disordered stiff extracellular matrix and fundamental alteration in the mechanical signaling pathways. Specifically, these alterations affect the normal dynamic state of responsiveness to mechanical cues in the extracellular environment. These mechanical cues are converted through integrins, cell membrane receptors, to biochemical signals including cytoskeletal signaling pathways to maintain mechanical homeostasis. Leiomyoma cells overexpress β1 integrin and other downstream mechanical signaling proteins. We previously reported that simvastatin, an antihyperlipidemic drug, has antileiomyoma effects through cellular, animal model, and epidemiologic studies.

OBJECTIVE

This study aimed to examine the hypothesis that simvastatin might influence altered mechanotransduction in leiomyoma cells.

STUDY DESIGN

This is a laboratory-based experimental study. Primary leiomyoma cells were isolated from 5 patients who underwent hysterectomy at the Department of Gynecology and Obstetrics of the Johns Hopkins University Hospital. Primary and immortalized human uterine leiomyoma cells were treated with simvastatin at increasing concentrations (0.001, 0.01, 0.1, and 1 μM, or control) for 48 hours. Protein and mRNA levels of β1 integrin and extracellular matrix components involved in mechanical signaling were quantified by quantitative real-time polymerase chain reaction, western blotting, and immunofluorescence. In addition, we examined the effect of simvastatin on the activity of Ras homolog family member A using pull-down assay and gel contraction.

RESULTS

We found that simvastatin significantly reduced the protein expression of β1 integrin by 44% and type I collagen by 60% compared with untreated leiomyoma cells. Simvastatin-treated cells reduced phosphorylation of focal adhesion kinase down to 26%-60% of control, whereas it increased total focal adhesion kinase protein expression. Using a Ras homolog family member A pull-down activation assay, we observed reduced levels of active Ras homolog family member A in simvastatin-treated cells by 45%-85% compared with control. Consistent with impaired Ras homolog family member A activation, simvastatin treatment reduced tumor gel contraction where gel area was 122%-153% larger than control. Furthermore, simvastatin treatment led to reduced levels of mechanical signaling proteins involved in β1 integrin downstream signaling, such as A-kinase anchor protein 13, Rho-associated protein kinase 1, myosin light-chain kinase, and cyclin D1.

CONCLUSION

The results of this study suggest a possible therapeutic role of simvastatin in restoring the altered state of mechanotransduction signaling in leiomyoma. Collectively, these findings are aligned with previous epidemiologic studies and other reports and support the need for clinical trials.

Recycling the Purpose of Old Drugs to Treat Ovarian Cancer

The main challenge in ovarian cancer treatment is the management of recurrences. Facing this scenario, therapy selection is based on multiple factors to define the best treatment sequence. Target therapies, such as bevacizumab and polymerase (PARP) inhibitors, improved patient survival. However, despite their achievements, ovarian cancer survival remains poor; these therapeutic options are highly costly and can be associated with potential side effects. Recently, it has been shown that the combination of repurposed, conventional, chemotherapeutic drugs could be an alternative, presenting good patient outcomes with few side effects and low costs for healthcare institutions. The main aim of this review is to strengthen the importance of repurposed drugs as therapeutic alternatives, and to propose an in vitro model to assess the therapeutic value. Herein, we compiled the current knowledge on the most promising non-oncological drugs for ovarian cancer treatment, focusing on statins, metformin, bisphosphonates, ivermectin, itraconazole, and ritonavir. We discuss the primary drug use, anticancer mechanisms, and applicability in ovarian cancer. Finally, we propose the use of these therapies to perform drug efficacy tests in ovarian cancer ex vivo cultures. This personalized testing approach could be crucial to validate the existing evidences supporting the use of repurposed drugs for ovarian cancer treatment.

Cardiometabolic Risk Factors and Benign Gynecologic Disorders

Importance

While it has long been known that polycystic ovarian syndrome is associated with cardiometabolic risk factors (CMRFs), there is emerging evidence that other benign gynecologic conditions, such as uterine leiomyomas, endometriosis, and even hysterectomy without oophorectomy, can be associated with CMRFs. Understanding the evidence and mechanisms of these associations can lead to novel preventive and therapeutic interventions.

Objective

This article discusses the evidence and the potential mechanisms mediating the association between CMRFs and benign gynecologic disorders.

Evidence Acquisition

We reviewed PubMed, EMBASE, Scopus, and Google Scholar databases to obtain plausible clinical and biological evidence, including hormonal, immunologic, inflammatory, growth factor-related, genetic, epigenetic, atherogenic, vitamin D-related, and dietary factors.

Results

Cardiometabolic risk factors appear to contribute to uterine leiomyoma pathogenesis. For example, obesity can modulate leiomyomatous cellular proliferation and extracellular matrix deposition through hyperestrogenic states, chronic inflammation, insulin resistance, and adipokines. On the other hand, endometriosis has been shown to induce systemic inflammation, thereby increasing cardiometabolic risks, for example, through inducing atherosclerotic changes.

Conclusion and Relevance

Clinical implications of these associations are 2-fold. First, screening and early modification of CMRFs can be part of a preventive strategy for uterine leiomyomas and hysterectomy. Second, patients diagnosed with uterine leiomyomas or endometriosis can be screened and closely followed for CMRFs and cardiovascular disease.

Statin use and the risk of ovarian and endometrial cancers: a meta-analysis

Background

The relationship between statin use and the risk of ovarian or endometrial cancer remains controversial. Here, we investigated the relationship between statin use and the risk of ovarian and endometrial cancers.

Methods

We conducted a meta-analysis using articles retrieved from the PubMed, Embase, and Web of Science databases. All original comparative studies published in English that were related to statin use and the risk of ovarian or endometrial cancer were included.

Results

This meta-analysis included 19 studies enrolling 1,999,362 female subjects and 19,849 cancer cases (7,948 ovarian cancer cases and 11,901 endometrial cancer cases). The overall analysis indicated that statin use did not significantly reduce the risk of ovarian cancer [relative risk (RR) = 0.88, 95% confidence interval (CI) 0.76–1.03, p = 0.12] or the risk of endometrial cancer (RR = 0.88, 95% CI 0.78–1.00, p = 0.05.) Subgroup analyses based on study type, percentage of cancer cases, study location, and quality of studies also supported our conclusions. No association was found between long-term statin use (> 5 years) and the risk of ovarian cancer (RR = 0.73, 95% CI 0.51–1.04, p = 0.08) or endometrial cancer (RR = 0.79, 95% CI 0.58–1.08, p = 0.14).

Conclusions

Statin use did not lower the risk of ovarian cancer or endometrial cancer. The long-term use of statins (> 5 years) was not associated with a reduction in the risk of ovarian or endometrial cancer.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5954-0) contains supplementary material, which is available to authorized users.

Simvastatin, at clinically relevant concentrations, affects human uterine leiomyoma growth and extracellular matrix production

OBJECTIVE

To observe the antifibroid effects of therapeutic concentrations of simvastatin, which interferes with cholesterol biosynthesis, a known precursor of five major classes of steroid hormones, including progesterone and estrogen, which play a major role in the development and growth of uterine leiomyomas.

DESIGN

Two-dimensional and three-dimensional cell culture study of immortalized human leiomyoma and patient-matched myometrium cells treated with simvastatin.

SETTING

University laboratory.

PATIENT(S)

None.

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

Cell proliferation, alteration in apoptotic signaling pathways, and extracellular matrix (ECM) protein production.

RESULT(S)

Simvastatin demonstrated a concentration-dependent antiproliferative effect on both the leiomyoma cells and the patient-matched myometrium cells, but a higher inhibitory effect at lower concentrations of simvastatin was observed in leiomyoma cells. Simvastatin also regulated leiomyoma cell apoptosis through a concentration-dependent increase in activity of caspase-3. Simvastatin significantly inhibited expression of major ECM proteins collagen I, collagen III, fibronectin, versican, and brevican in leiomyoma cells at concentrations as low as 10^-9 mol/L within 48 hours of exposure.

CONCLUSION(S)

Simvastatin induces apoptosis in uterine leiomyoma cells at low concentrations, as evidenced by increased active caspase levels. Furthermore, inhibited production of the ECM proteins may lead to reduction in tumor size. Simvastatin may represent a novel therapeutic treatment strategy for uterine leiomyomas.

Physiology and Pathophysiology of Steroid Biosynthesis, Transport and Metabolism in the Human Placenta

The steroid hormones progestagens, estrogens, androgens, and glucocorticoids as well as their precursor cholesterol are required for successful establishment and maintenance of pregnancy and proper development of the fetus. The human placenta forms at the interface of maternal and fetal circulation. It participates in biosynthesis and metabolism of steroids as well as their regulated exchange between maternal and fetal compartment. This review outlines the mechanisms of human placental handling of steroid compounds. Cholesterol is transported from mother to offspring involving lipoprotein receptors such as low-density lipoprotein receptor (LDLR) and scavenger receptor class B type I (SRB1) as well as ATP-binding cassette (ABC)-transporters, ABCA1 and ABCG1. Additionally, cholesterol is also a precursor for placental progesterone and estrogen synthesis. Hormone synthesis is predominantly performed by members of the cytochrome P-450 (CYP) enzyme family including CYP11A1 or CYP19A1 and hydroxysteroid dehydrogenases (HSDs) such as 3β-HSD and 17β-HSD. Placental estrogen synthesis requires delivery of sulfate-conjugated precursor molecules from fetal and maternal serum. Placental uptake of these precursors is mediated by members of the solute carrier (SLC) family including sodium-dependent organic anion transporter (SOAT), organic anion transporter 4 (OAT4), and organic anion transporting polypeptide 2B1 (OATP2B1). Maternal-fetal glucocorticoid transport has to be tightly regulated in order to ensure healthy fetal growth and development. For that purpose, the placenta expresses the enzymes 11β-HSD 1 and 2 as well as the transporter ABCB1. This article also summarizes the impact of diverse compounds and diseases on the expression level and activity of the involved transporters, receptors, and metabolizing enzymes and concludes that the regulatory mechanisms changing the physiological to a pathophysiological state are barely explored. The structure and the cellular composition of the human placental barrier are introduced. While steroid production, metabolism and transport in the placental syncytiotrophoblast have been explored for decades, few information is available for the role of placental-fetal endothelial cells in these processes. With regard to placental structure and function, significant differences exist between species. To further decipher physiologic pathways and their pathologic alterations in placental steroid handling, proper model systems are mandatory.