Endometriosis-Associated Ovarian Cancer: From Molecular Pathologies to Clinical Relevance

Endometriosis is a chronic condition affecting reproductive-aged women, characterized by the growth of ectopic endometrial tissue. Despite being benign, endometriosis is associated with an increased risk of certain cancers, including endometriosis-associated ovarian cancer (EAOC). Ovarian cancer is rare, but more common in women with endometriosis, particularly endometrioid and clear-cell carcinomas. Factors such as hormonal imbalance, reproductive history, environmental exposures, and genetic predisposition contribute to the malignant transformation of endometriosis. Thus, understanding potential risk factors causing malignancy is crucial. Over the past few decades, various genetic mutations, microRNAs, as well as tumor microenvironmental factors have been identified, impacting pathways like PI3K/AKT/mTOR, DNA repair mechanisms, oxidative stress, and inflammation. Thus, this review aims to summarize molecular studies involved in EAOC pathogenesis as potential therapeutic targets. However, further research is needed to better understand the molecular and environmental factors driving EAOC development, to target the susceptibility of endometriotic lesions to malignant progression, and to identify effective therapeutic strategies.

Expression of miR-21 &IL-4 in endometriosis

BACKGROUND

Endometriosis characterized with existence of endometrial-like tissue outside the uterus. Fibrosis of ectopic lesions is an important feature of endometriosis. IL-4 induces fibrosis via fibroblast proliferation, collagen production and myofibroblast differentiation. Increasing of miR-21 expression promotes fibroblast activation and fibrosis expansion. The aim of study was to evaluate the expression of miR-21 and its relationship with IL-4 gene expression in endometrial ectopic and eutopic tissues of endometriosis patients.

METHODS AND RESULTS

Ectopic and eutopic tissue samples were taken from 20 women with endometriosis, and control samples were taken from the endometrium of 20 endometriosis-free women. The relative expression of IL-4 and miR-21 evaluated by Real Time PCR. IL-4 relative gene expression was significantly increased in ectopic tissue compared to eutopic (p = 0.025) and control tissue (p = 0.021). The relative expression of miR-21 gene in ectopic tissue was increased compared to eutopic (p = 0.850) and control tissue (p = 0.978) but these differences were not significant. Also, the correlation between IL-4 and miR-21 relative gene expression was not significant (p = 0.083).

CONCLUSION

The increased expression of miR-21 in endometrium of women with endometriosis may upregulate the IL-4 gene expression and lead to fibrosis. Further studies may suggest miR-21 and IL-4 as candidates for diagnosis of endometriosis.

The Pathological Role of miRNAs in Endometriosis

Association studies investigating miRNA in relation to diseases have consistently shown significant alterations in miRNA expression, particularly within inflammatory pathways, where they regulate inflammatory cytokines, transcription factors (such as NF-κB, STAT3, HIF1α), and inflammatory proteins (including COX-2 and iNOS). Given that endometriosis (EMS) is characterized as an inflammatory disease, albeit one influenced by estrogen levels, it is natural to speculate about the connection between EMS and miRNA. Recent research has indeed confirmed alterations in the expression levels of numerous microRNAs (miRNAs) in both endometriotic lesions and the eutopic endometrium of women with EMS, when compared to healthy controls. The undeniable association of miRNAs with EMS hints at the emergence of a new era in the study of miRNA in the context of EMS. This article reviews the advancements made in understanding the pathological role of miRNA in EMS and its association with EMS-associated infertility. These findings contribute to the ongoing pursuit of developing miRNA-based therapeutics and diagnostic markers for EMS.

Vascularisation in Deep Endometriosis: A Systematic Review with Narrative Outcomes

Deep endometriosis (DE) is the most severe subtype of endometriosis, with the hallmark of lesions infiltrating adjacent tissue. Abnormal vascularisation has been implicated in contributing to endometriosis lesion development in general, and how vascularisation influences the pathogenesis of DE, in particular, is of interest. This systematic review followed the PRISMA guidelines to elucidate and examine the evidence for DE-specific vascularisation. A literature search was performed using MEDLINE, Embase, PubMed, Scopus, Cochrane CENTRAL Library and Europe PubMed Central databases. The databases were searched from inception to the 13 March 2023. A total of 15 studies with 1125 patients were included in the review. The DE lesions were highly vascularised, with a higher microvessel density (MVD) than other types of endometriotic lesions, eutopic endometrium from women with endometriosis and control tissue. Vascular endothelial growth factor, its major subtype (VEGF-A) and associated receptor (VEGFR-2) were significantly increased in the DE lesions compared to superficial endometriosis, eutopic endometrium and control tissue. Progestin therapy was associated with a significant decrease in the MVD of the DE lesions, explaining their therapeutic effect. This review comprehensively summarises the available literature, reporting abnormal vascularisation to be intimately related to the pathogenesis of DE and presents potentially preferential therapeutic targets for the medical management of DE.

The Expression of TGF-β1, SMAD3, ILK and miRNA-21 in the Ectopic and Eutopic Endometrium of Women with Endometriosis

The molecular pathogenesis of endometriosis has been associated with pathological alterations of protein expression via disturbances in homeostatic genes, miRNA expression profiles, and signaling pathways that play an essential role in the epithelial-mesenchymal transition (EMT) process. TGF-β1 has been hypothesized to play a key role in the development and progression of endometriosis, but the activation of a specific mechanism via the TGF-β-SMAD-ILK axis in the formation of endometriotic lesions is poorly understood. The aim of this study was to assess the expression of EMT markers (TGF-β1, SMAD3, ILK) and miR-21 in ectopic endometrium (ECE), in its eutopic (EUE) counterpart, and in the endometrium of healthy women. The expression level of the tested genes and miRNA was also evaluated in peripheral blood mononuclear cells (PBMC) in women with and without endometriosis. Fifty-four patients (n = 54; with endometriosis, n = 29, and without endometriosis, n = 25) were enrolled in the study. The expression levels (RQ) of the studied genes and miRNA were evaluated using qPCR. Endometriosis patients manifested higher TGF-β1, SMAD3, and ILK expression levels in the eutopic endometrium and a decreased expression level in the ectopic lesions in relation to control tissue. Compared to the endometrium of healthy participants, miR-21 expression levels did not change in the eutopic endometrium of women with endometriosis, but the RQ was higher in their endometrial implants. In PBMC, negative correlations were found between the expression level of miR-21 and the studied genes, with the strongest statistically significant correlation observed between miR-21 and TGF-β1. Our results suggest the loss of the endometrial epithelial phenotype defined by the differential expression of the TGF-β1, SMAD3 and ILK genes in the eutopic and ectopic endometrium. We concluded that the TGF-β1-SMAD3-ILK signaling pathway, probably via a mechanism related to the EMT, may be important in the pathogenesis of endometriosis. We also identified miR-21 as a possible inhibitor of this TGF-β1-SMAD3-ILK axis.

Endometrial Cells Acutely Exposed to Phthalates In Vitro Do Not Phenocopy Endometriosis

Environmental factors that have been linked to an increased endometriosis risk include exposure to di-(2-ethylhexyl)-phthalate (DEHP), an endocrine disruptor. This study aims to investigate whether DEHP in vitro exposure in primary endometrial stromal cells (EnSC), primary endometrial epithelial cells (EnEC), and the human endometrial adenocarcinoma cell line Ishikawa properly mimics alterations described in the eutopic endometrium of women with endometriosis. Primary EnSC and EnEC, isolated from six fertile egg donors, and Ishikawa cells were exposed to DEHP (0.1, 1, and 10 µM) and were assessed for viability, endometriosis markers (IL-6, VEGF-A, HOXA10, EZH2, and LSD1), steroid receptor gene expressions (ER-1, ER-2, PR-T, PR-B, and PGRMC1), and invasive capacity. Viability after 72 h of DEHP exposure was not significantly affected. None of the endometriosis markers studied were altered after acute DEHP exposure, nor was the expression of steroid receptors. The invasive capacity of EnSC was significantly increased after 10 µM of DEHP exposure. In conclusion, acute DEHP exposure in primary endometrial cells does not fully phenocopy the changes in the viability, expression of markers, or steroidal receptors described in endometriosis. However, the significant increase in EnSC invasiveness observed after DEHP exposure could be a link between DEHP exposure and increased endometriosis likelihood.

Genes Relating to Biological Processes of Endometriosis: Expression Changes Common to a Mouse Model and Patients

Endometriosis is one of the most common gynecological diseases in women of reproductive age. Retrograde menstruation is considered a major reason for the development of endometriosis. The syngeneic transplantation mouse model is an endometriosis animal model that is considered to mimic retrograde menstruation. However, it remains poorly understood which genetic signatures of endometriosis are reflected in this model. Here, we employed an in vivo syngeneic mouse endometriosis model and identified differentially expressed genes (DEGs) between the ectopic and eutopic tissues using microarray analysis. Three gene expression profile datasets, GSE5108, GSE7305, and GSE11691, were downloaded from the Gene Expression Omnibus database and DEGs between ectopic and eutopic tissues from the same patients were identified. Gene ontology analysis of the DEGs revealed that biological processes including cell adhesion, the inflammatory response, the response to mechanical stimulus, cell proliferation, and extracellular matrix organization were enriched in both the model and patients. Of the 195 DEGs common to the model and patients, 154 showed the same expression pattern, and 28 of these 154 DEGs came up when PubMed was searched for each gene along with the terms "endometriosis" and "development". This is the first comparison of the DEGs of the mouse syngeneic endometriosis model and those of patients, and we identified the biological processes common to the model and patients at the transcriptional level. This model may be useful to evaluate the efficacy of drugs which target these biological processes.

Roles of microRNAs in Regulating Apoptosis in the Pathogenesis of Endometriosis

Endometriosis is a gynecologic disorder characterized by the presence of endometrial tissues outside the uterine cavity affecting reproductive-aged women. Previous studies have shown that microRNAs and their target mRNAs are expressed differently in endometriosis, suggesting that this molecule may play a role in the development and persistence of endometriotic lesions. microRNA (miRNA), a small non-coding RNA fragment, regulates cellular functions such as cell proliferation, differentiation, and apoptosis by the post-transcriptional modulation of gene expression. In this review, we focused on the dysregulated miRNAs in women with endometriosis and their roles in the regulation of apoptosis. The dysregulated miRNAs and their target genes in this pathophysiology were highlighted. Circulating miRNAs as potential biomarkers for the diagnosis of endometriosis have also been identified. As shown by various studies, miRNAs were reported to be a potent regulator of gene expression in endometriosis; thus, identifying the dysregulated miRNAs and their target genes could help discover new therapeutic targets for treating this disease. The goal of this review is to draw attention to the functions that miRNAs play in the pathophysiology of endometriosis, particularly those that govern cell death.

Unbiased In Silico Analysis of Gene Expression Pinpoints Circulating miRNAs Targeting KIAA1324, a New Gene Drastically Downregulated in Ovarian Endometriosis

Objective: To identify circulating miRNAs associated with ovarian endometriosis (OMA), and to analyze candidate genes targeted by these miRNAs. Methods: Putative regulating miRNAs were identified through an original bioinformatics approach. We first queried the miRWalk 2.0 database to collect putative miRNA targets. Then, we matched it to a transcriptomic dataset of OMA. Moving from gene expression in the tissue to possible alterations in the patient plasma, a selection of these miRNAs was quantified by qRT-PCR in plasma samples from 93 patients with isolated OMA and 95 patients surgically checked as free from endometriosis. Then, we characterized the genes regulated by more than one miRNA and validated them by immunohistochemistry and transfection experiments on endometrial cell primary cultures obtained from endometrial biopsies of 10 women with and without endometriosis with miRNA mimics. Stromal and epithelial cells were isolated and cultured separately and gene expression levels were measured by RT-qPCR. Results: Eight miRNAs were identified by bioinformatics analysis. Two of them were overexpressed in plasma from OMA patients: let-7b-5p and miR-92a-3p (p < 0.005). Three miRNAs, let-7b and miR-92a-3p, and miR-93-5p potentially targeted KIAA1324, an estrogen-responsive gene and one of the most downregulated genes in OMA. Transfection experiments with mimics of these two miRNAs showed a strong decrease in KIAA1324 expression, up to 40%. Immunohistochemistry revealed a moderate-to-intense staining for KIAA1324 in the eutopic endometrium and a faint-to-moderate staining in the ectopic endometrium for half of the samples, which is concordant with the transcriptomic data. Discussion and Conclusion: Our results suggested that KIAA1324 might be involved in endometriosis through the downregulating action of two circulating miRNAs. As these miRNAs were found to be overexpressed, their quantification in plasma could provide a tool for an early diagnosis of endometriosis.

Integrated bioinformatic analysis of dysregulated microRNA-mRNA co-expression network in ovarian endometriosis

INTRODUCTION

Ovarian endometriosis is a frequently occurring gynecological disease with large socioeconomic impact. Accumulating evidence has suggested that aberrant miRNA-mRNA interactions are involved in the pathogenesis and progression of ovarian endometriosis. This study aims to identify key miRNAs in ovarian endometriosis by using integrated bioinformatic analysis of a dysregulated miRNA-mRNA co-expression network.

MATERIAL AND METHODS

Expression profiling of miRNA and mRNA in three normal endometria and five pairs of ectopic/eutopic endometria from patients with ovarian endometriosis was determined by high-throughput sequencing techniques. The data were then integrated with the public sequencing datasets (GSE105764 and GSE105765) using a non-biased approach and a miRNA-mRNA co-expression regulatory network was constructed by in-depth bioinformatic analysis.

RESULTS

The constructed miRNA-mRNA network included 87 functionally DEMs, 482 target mRNAs and 1850 paired miRNA-mRNA regulatory interactions. Specifically, five miRNAs (miR-141-3p, miR-363-3p, miR-577, miR-767-5p, miR-96-5p) were gradually decreased and two miRNAs (miR-493-5p, miR-592) were gradually increased from normal endometria to eutopic endometria, and then ectopic endometria tissues. Importantly, miR-141-3p, miR-363-3p and miR-96-5p belonged to the miR-200 family, miR-106a-363 cluster and miR-183/96/182 cluster, respectively. Their target mRNAs were mainly associated with cell adhesion, locomotion and binding, which are suggested to play vital regulatory roles in the pathogenesis of ovarian endometriosis.

CONCLUSIONS

Integrated bioinformatic analysis of the miRNA-mRNA co-expression network defines the crucial roles of the miR-200 family, miR-106a-363 cluster and miR-183/96/182 cluster in the pathogenesis of ovarian endometriosis. Further in-depth functional studies are needed to unveil the molecular mechanisms of these miRNAs, and may provide clues for the optimization of therapeutic strategies for ovarian endometriosis.

Inflammatory MicroRNAs and the Pathophysiology of Endometriosis and Atherosclerosis: Common Pathways and Future Directions Towards Elucidating the Relationship

Emerging data indicates an association between endometriosis and subclinical atherosclerosis, with women with endometriosis at a higher risk for cardiovascular disease later in life. Inflammation is proposed to play a central role in the pathophysiology of both diseases and elevated levels of systemic pro-inflammatory cytokines including macrophage migration inhibitory factor (MIF), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) are well documented. However, a thorough understanding on the mediators and mechanisms which contribute to altered cytokine expression in both diseases remain poorly understood. MicroRNAs (miRNAs) are important post-transcriptional regulators of inflammatory pathways and numerous studies have reported altered circulating levels of miRNAs in both endometriosis and atherosclerosis. Potential contribution of miRNA-mediated inflammatory cascades common to the pathophysiology of both diseases has not been evaluated but could offer insight into common pathways and early manifestation relevant to both diseases which may help understand cause and effect. In this review, we discuss and summarize differentially expressed inflammatory circulating miRNAs in endometriosis subjects, compare this profile to that of circulating levels associated with atherosclerosis when possible, and then discuss mechanistic studies focusing on these miRNAs in relevant cell, tissue, and animal models. We conclude by discussing the potential utility of targeting the relevant miRNAs in the MIF-IL-6-TNF-α pathway as therapeutic options and offer insight into future studies which will help us better understand not only the role of these miRNAs in the pathophysiology of both endometriosis and atherosclerosis but also commonality between both diseases.

Altered gene expression of VEGF, IGFs and H19 lncRNA and epigenetic profile of H19-DMR region in endometrial tissues of women with endometriosis

Background

Endometriosis, as chronic estrogen-dependent disease, is defined by the presence of endometrial-like tissue outside the uterus. Proliferation of endometrial tissue and neoangiogenesis are critical factors in development of endometriosis. Hence, vascular endothelial growth factor (VEGF) as well as insulin‐like growth factor 1 and 2 (IGF1, 2) may be involved as inducers of cellular proliferation or neoangiogenesis. Imprinted long noncoding RNA H19 (lncRNA H19) has been suggested to be involved in pathogenesis of endometriosis via regulation of cellular proliferation and differentiation. Epigenetic aberrations appear to play an important role in its pathogenesis. The present study was designed to elucidate VEGF, IGF1, IGF2 and H19 lncRNA genes expression and epigenetic alterations of differentially methylated region (DMR) of H19 (H19-DMR) regulatory region in endometrial tissues of patients with endometriosis, in comparison with control women.

Methods

In this case–control study, 24 women with and without endometriosis were studied for the relative expression of VEGF, IGF1, IGF2 and H19 lncRNA genes using real-time polymerase chain reaction (PCR) technique. Occupancy of the MeCP2 on DMR region of H19 gene was assessed using chromatin immunoprecipitation (ChIP), followed by real-time PCR.

Results

Genes expression profile of H19, IGF1 and IGF2 was decreased in eutopic and ectopic endometrial tissues of endometriosis group, compared to the control tissues. Decreased expression of H19 in ectopic samples was significant in comparison with the controls (P < 0.05). Gene expression of VEGF was increased in eutopic tissues of endometriosis group, compared to control group. Whereas its expression level was lower in ectopic lesions versus eutopic and control endometrial samples. ChIP analysis revealed significant and nearly significant hypomethylation of H19-DMR region II in eutopic and ectopic samples, compared to the control group respectively. This epigenetic change was aligned with expression of IGF2. While methylation of H19-DMR region I was not significantly different between the eutopic, ectopic and control endometrial samples.

Conclusion

These data showed that VEGF, IGF1, IGF2 and H19 lncRNA genes expression and epigenetic alterations of H19 lncRNA have dynamic role in the pathogenesis of endometriosis, specifically in the way that hypomethylation of H19-DMR region II can be involved in IGF2 dysregulation in endometriosis.

Overexpression of miR-200b-3p in Menstrual Blood-Derived Mesenchymal Stem Cells from Endometriosis Women

The key relationship between Sampson's theory and the presence of mesenchymal stem cells in the menstrual flow (MenSCs), as well as the changes in post-transcriptional regulatory processes as actors in the etiopathogenesis of endometriosis, are poorly understood. No study to date has investigated the imbalance of miRNAs in MenSCs related to the disease. Thus, through literature and in silico analyses, we selected four predicted miRNAs as regulators of EGR1, SNAI1, NR4A1, NR4A2, ID1, LAMC3, and FOSB involved in pathways of apoptosis, angiogenesis, response to steroid hormones, migration, differentiation, and cell proliferation. These genes are frequently overexpressed in the endometriosis condition in our group studies. They were the trigger for the miRNAs search. Therefore, a case-control study was conducted with MenSCs of women with and without endometriosis (ten samples per group). Crossing information obtained from the STRING, PubMed, miRPathDB, miRWalk, and DIANA TOOLS databases, we chose to explore the expression of miR-21-5p, miR-100-5p, miR-143-3p, and miR-200b-3p by RT-qPCR. We found an upregulation of the miR-200b-3p in endometriosis MenSCs (P = 0.0207), with a 7.93-fold change (ratio of geometric means) compared to control. Overexpression of miR-200b has been associated with increased cell proliferation, stemness, and accentuated mesenchymal-epithelial transition process in eutopic endometrium of endometriosis. We believe that dysregulated miR-200b-3p may establish primary changes in the MenSCs, thus favoring tissue implantation at the ectopic site.

Endometriosis stem cell sources and potential therapeutic targets: literature review and bioinformatics analysis

The stem cell origin theory of endometriosis (EMS) is a significant area of new research but the sources of this have yet to be adequately summarized. Existing treatments for EMS are commonly associated with a high recurrence rate; consequently, there is an urgent need to develop new therapeutic measures for the future treatment of this disease from the view of stem cells and gene therapy. Recently, we described the evidence for the potential sources of EMS stem cells and other key molecules participating in the establishment of lesions, and predict the miRNAs that target these key genes via bioinformatics analysis for further research. This review highlights the origin of EMS stem cells and potential therapy targets.

Circulating miRNAs Related to Epithelial-Mesenchymal Transitions (EMT) as the New Molecular Markers in Endometriosis

Endometriosis is a chronic gynecological disease defined by the presence of endometrial-like tissue found outside the uterus, most commonly in the peritoneal cavity. Endometriosis lesions are heterogenous but usually contain endometrial stromal cells and epithelial glands, immune cell infiltrates and are vascularized and innervated by nerves. The complex etiopathogenesis and heterogenity of the clinical symptoms, as well as the lack of a specific non-invasive diagnostic biomarkers, underline the need for more advanced diagnostic tools. Unfortunately, the contribution of environmental, hormonal and immunological factors in the disease etiology is insufficient, and the contribution of genetic/epigenetic factors is still fragmentary. Therefore, there is a need for more focused study on the molecular mechanisms of endometriosis and non-invasive diagnostic monitoring systems. MicroRNAs (miRNAs) demonstrate high stability and tissue specificity and play a significant role in modulating a range of molecular pathways, and hence may be suitable diagnostic biomarkers for the origin and development of endometriosis. Of these, the most frequently studied are those related to endometriosis, including those involved in epithelial–mesenchymal transition (EMT), whose expression is altered in plasma or endometriotic lesion biopsies; however, the results are ambiguous. Specific miRNAs expressed in endometriosis may serve as diagnostics markers with prognostic value, and they have been proposed as molecular targets for treatment. The aim of this review is to present selected miRNAs associated with EMT known to have experimentally confirmed significance, and discuss their utility as biomarkers in endometriosis.

VEGF-mediated angiogenesis in retinopathy of prematurity is co-regulated by miR-17-5p and miR-20a-5p

The microRNAs miR-17-5p and miR-20a-5p play important roles on angiogenesis; however, it is arguable whether they regulate the formation of retinal blood vessels in retinopathy of prematurity (ROP). We used a mouse model of oxygen-induced retinopathy (OIR) to simulate the development of retinas in mice suffering from ROP, and the expression levels of miR-20a-5p, miR-17-5p, hypoxia-inducible factor 1-alpha (HIF-1α), and vascular endothelial growth factor (VEGF) were measured by RT-qPCR and Western blotting. Cell proliferation, apoptosis, and angiogenesis in the OIR model mice were measured using MTT assays, flow cytometry, and Matrigel assays, respectively. The interaction between HIF-1α/VEGF and miR-20a-5p/miR-17-5p were further validated using dual-luciferase reporter assays, biotin-labeled RNA-pulldown, and RNA immunoprecipitation (RIP) assays. In our OIR model, retinal angiogenesis in the mice was associated with down-regulation of miR-20a-5p and miR-17-5p, as well as up-regulation of HIF-1α and VEGF. In addition, the miR-20a-5p and miR-17-5p inhibited cell proliferation and angiogenesis through regulating HIF-1α and VEGF in the retinal cells of the OIR model mice. Moreover, it was found that miR-20a-5p and miR-17-5p bind to HIF-1α and VEGF at the 3'UTR, and there was a combined effect between miR-20a-5p and miR-17-5p on the regulation of HIF-1α and VEGF. It is worth noting that miR-17-5p and miR-20a-5p can preferentially regulate HIF-1α, then act on VEGF, thereby affecting the angiogenesis associated with ROP.

Endometriosis: New Perspective for the Diagnosis of Certain Cytokines in Women and Adolescent Girls, as Well as the Progression of Disease Outgrowth: A Systematic Review

Endometriosis is a common chronic gynecological disorder that undoubtedly impacts on quality of life, and is one of the more complex and mysterious illnesses of our century, which is associated with the improper growth of endometrial tissue outside of the uterine cavity. This pathologically implanted tissue can be found most frequently in the minor pelvis, but also in the peritoneal cavity, and can affect many organs, leading to chronic pelvic pain syndrome, infertility, and dysmenorrhea. Endometrial tissue is a particularly dynamic tissue that has a direct impact on the progression of the disease, with altered immunity, as well as cytokine storms within the metaplastic endometriotic site, as possible key factors. Currently, diagnosis of this mysterious chronic illness relies on performing a laparoscopic procedure with tissue sampling. One of the most troublesome outcomes of this unintended progression is that we lack any specific, sensitive, non-invasive diagnostic tools. Currently, the vast majority of regime stewardship options rely on anti-contraceptive drugs, or other remedies that suppress the release of estrogen through the gonads-although in most clinical trials, endometriosis is a chronic progressive disorder that depends mostly on the high concentration of estrogen. Moreover, many specific trials have demonstrated that the eutopic endometrial cells in individuals with endometriosis remain much more resistant to the immunological annihilation process caused by certain elements of the immune system. Nevertheless, eutopic endometrial cells have the potential to similarly escalate the expression of aromatase receptors on the surface of the pathological cells, which in the final cascade cause an increase in the concentration of estrogen, as well as other inflammatory proteins that contribute to pathological outgrowth. Data reveal occurrence among first-degree relatives, suggesting that the specific cascade could be related to inherited as well as epigenetic (acquired) mechanisms. In women with the disease, confirmed by laparoscopic procedures, diagnosis of endometriosis can be established also via detection by gene polymorphism in the genes which are responsible for responsible for the detoxification phase of estrogen receptors and other immunomodulator components. A recent publication aims to reveal a new prospect for the non-invasive diagnosis, detection, and estimation of certain biomarkers for much more specific investigation of the disease's progression.

Overview of miRNAs for the non-invasive diagnosis of endometriosis: evidence, challenges and strategies. A systematic review

OBJECTIVE

The aim of the study was to assess the evidence on miRNAs as biomarkers for the diagnosis of endometriosis, as well as to provide insights into the challenges and strategies associated with the use of these molecules as accessible tools in clinical practice.

METHODS

Systematic review conducted on PubMed®, Latin American and Caribbean Health Sciences Literature (LILACS), MEDLINE® and Web of Science databases using the search terms endometriosis (all fields) AND miRNA (all fields), evaluating all publication up to May 2019.

RESULTS

Most miRNAs found to be dysregulated in this study were harvested from tissue samples, which precludes their use as a non-invasive diagnostic test. However, differential expression of 62 miRNAs was reported in samples that may be used for non-invasive diagnosis of endometriosis, such as blood, serum and plasma.

CONCLUSION

Despite the identification of several candidates, studies are investigatory in nature and have been conducted with small number of samples. Also, no particular miRNA has been validated for diagnostic purposes so far. Studies based primarily on biological samples and applicable to translational research are warranted. Large databases comprising information on sample type and the use of saliva and vaginal fluid for miRNAs identification may prove essential to overcome current barriers to diagnosis of endometriosis.

Construction of miRNA-mRNA Regulatory Network and Prognostic Signature in Endometrial Cancer

Introduction

This bioinformatic study confirmed a new miRNA-mRNA regulatory network and a prognostic signature in endometrial cancer (EC).

Materials and Methods

We downloaded RNA-seq and miRNA-seq data of EC from the TCGA database, then used EdegR package to screen differentially expressed miRNAs and mRNAs (DE-miRNAs and DE-mRNAs). Then, we constructed a regulatory network of EC-associated miRNAs and hub genes by Cytoscape, and determined the expression of unexplored miRNAs in EC tissues and normal adjacent tissues by quantitative Real-Time PCR (qRT-PCR). A prognostic signature model and a predictive nomogram were constructed. Finally, we explored the association between the prognostic model and the immune cell infiltration.

Results

A total of 11,531 DE-mRNAs and 236 DE-miRNAs, as well as 275 and 118 candidate DEGs for upregulated and downregulated DE-miRNAs were screened out. The miRNA-mRNA network included 5 downregulated and 13 upregulated DE-miRNAs. qRT-PCR proved that the expression levels of miRNA-18a-5p, miRNA-18b-5p, miRNA-449c-5p and miRNA-1224-5p and their target genes (NR3C1, CTGF, MYC, and TNS1) were consistent with our predictions. Univariate and multivariate Cox proportional hazards regression analyses of the hub genes revealed a significant prognostic value of NR3C1, EZH2, AND GATA4, and these genes were closely related to eight types of immune infiltration cells.

Conclusion

We identified three genes as candidate biomarkers for EC, which may provide a theoretical basis for targeted therapy.

Nanoparticles in pregnancy: the next frontier in reproductive therapeutics

BACKGROUND

Nanotechnology involves the engineering of structures on a molecular level. Nanomedicine and nano-delivery systems have been designed to deliver therapeutic agents to a target site or organ in a controlled manner, maximizing efficacy while minimizing off-target effects of the therapeutic agent administered. In both reproductive medicine and obstetrics, developing innovative therapeutics is often tempered by fears of damage to the gamete, embryo or developing foetus or of negatively impacting a woman's reproductive potential. Thus, nanomedicine delivery systems may provide alternative targeted intervention strategies, treating the source of the disease and minimizing long-term consequences for the mother and/or her foetus.

OBJECTIVE AND RATIONALE

This review summarizes the current state of nanomedicine technology in reproductive medicine and obstetrics, including safety, potential applications, future directions and the hurdles for translation.

SEARCH METHODS

A comprehensive electronic literature search of PubMed and Web of Science databases was performed to identify studies published in English up until February 2020. Relevant keywords were used to obtain information regarding use of nanoparticle technology in fertility and gene therapy, early pregnancy complications (ectopic pregnancy and gestational trophoblastic disease) and obstetric complications (preeclampsia, foetal growth restriction, preterm birth and gestational diabetes) and for selective treatment of the mother or foetus. Safety of specific nanoparticles to the gamete, embryo and foetus was also investigated.

OUTCOMES

Pre-clinical research in the development of nanoparticle therapeutic delivery is being undertaken in many fields of reproductive medicine. Non-hormonal-targeted nanoparticle therapy for fibroids and endometriosis may provide fertility-sparing medical management. Delivery of interventions via nanotechnology provides opportunities for gene manipulation and delivery in mammalian gametes. Targeting cytotoxic treatments to early pregnancy tissue provides an alternative approach to manage ectopic pregnancies and gestational trophoblastic disease. In pregnancy, nanotherapeutic delivery offers options to stably deliver silencing RNA and microRNA inhibitors to the placenta to regulate gene expression, opening doors to novel genetic treatments for preeclampsia and foetal growth restriction. Restricting delivery of teratogenic drugs to the maternal compartment (such as warfarin) may reduce risks to the foetus. Alternatively, targeted delivery of drugs to the foetus (such as those to treat foetal arrythmias) may minimize side effects for the mother.

WIDER IMPLICATIONS

We expect that further development of targeted therapies using nanoparticles in a reproductive setting has promise to eventually allow safe and directed treatments for conditions impacting the health and reproductive capacity of women and for the management of pregnancy and serious pregnancy complications.

Identification of candidate microRNA markers of endometriosis with the use of next-generation sequencing and quantitative real-time polymerase chain reaction

OBJECTIVE

To identify novel candidate diagnostic microRNA (miRNA) markers of endometriosis by means of an unbiased search with confirmation by means of targeted polymerase chain reaction (PCR).

DESIGN

Retrospective cohort.

SETTING

University teaching hospitals.

PATIENT(S)

Women with endometriosis and control women, confirmed with the use of laparoscopy.

INTERVENTIONS(S)

Diagnostic laparoscopy and blood sample.

MAIN OUTCOME MEASURE(S)

Next-generation sequencing (NGS) and quantitative real-time PCR (qRT-PCR).

RESULT(S)

Candidate miRNAs differentially expressed in women with endometriosis compared with control women were identified by means of NGS and selected for qRT-PCR. Plasma samples from another cohort of women with surgically confirmed endometriosis (n = 53) and disease-free control women (n = 53) were checked for hemolysis using spectrophotometry and the ratio of miR-23a and miR-451 by means of qRT-PCR. MicroRNA signatures were quantified by means of qRT-PCR in hemolysis-free plasma samples of case subjects (n = 25) and control subjects (n = 28) with the use of miRcury LNA miRNA. Circulating levels of eight miRNAs (miR-199a-3p, miR-143-3p, miR-340-5p, let-7b-5p, miR-21-5p, miR-17-5p, miR-20a-5p, and miR-103a-3p) were significantly lower in case subjects compared to control subjects. The sensitivity and specificity for individual miRNAs ranged from 0.36 to 1.00 and from 0.43 to 1.00, respectively, but when combined produced sensitivity and specificity of 0.92 and 0.86 with positive (PPV) and (NPV) predictive values of 0.85 and 0.92, respectively. However, combination of five miRNAs (miR-17-5p, miR-20a-5p, miR-199a-3p, miR-143-3p, and let-7b-5p) produced sensitivity and specificity of 0.96 and 0.79 with PPV and NPV of 0.80 and 0.96, respectively.

CONCLUSION(S)

We conclude that a panel of candidate miRNAs was comparable to laparoscopy in distinguishing between women with endometriosis and control women.

Exosomes: Emerging biomarkers and targets in folliculogenesis and endometriosis

An appropriate connection of the cells in the ovary follicles is vital for a healthy ovule maturation and fertilization, and also for endometrium preparation for implantation that can cause endometriosis. Cellular communication within the follicle and endometrial epithelium involve many signaling molecules. Recent studies indicate that cellular communication can be enclosed by secretion and absorption of small membrane carriers which are named extracellular vesicles including exosomes and microvesicles. Understanding and defining these EVs (Extracellular vesicles) population are important for future studies and clinical translation. Here, we describe the various important cargos which are carried by exosomes during folliculogenesis and endometriosis. Additionally, the current knowledge of exosomes and their cargo within the FF (Follicular fluid) during the folliculogenesis and also in the intrauterine cavity which are involved in endometriosis lesions have also been summarized. Considering the potential importance of this form of the cell to cell communication in the reproductive system, the vital issues under discussion lead to a new insight in this rapidly expanding field and it may be an interesting approach for diagnostic, prognostic and especially therapeutic strategies in the field of infertility and assisted reproductive technology (ART).

MicroRNAs in endometriosis: biological function and emerging biomarker candidates†

MicroRNAs (miRNAs), a class of small noncoding RNA molecules, have been recognized as key post-transcriptional regulators associated with a multitude of human diseases. Global expression profiling studies have uncovered hundreds of miRNAs that are dysregulated in several diseases, and yielded many candidate biomarkers. This review will focus on miRNAs in endometriosis, a common chronic disease affecting nearly 10% of reproductive-aged women, which can cause pelvic pain, infertility, and a myriad of other symptoms. Endometriosis has delayed time to diagnosis when compared to other chronic diseases, as there is no current accurate, easily accessible, and noninvasive tool for diagnosis. Specific miRNAs have been identified as potential biomarkers for this disease in multiple studies. These and other miRNAs have been linked to target genes and functional pathways in disease-specific pathophysiology. Highlighting investigations into the roles of tissue and circulating miRNAs in endometriosis, published through June 2018, this review summarizes new connections between miRNA expression and the pathophysiology of endometriosis, including impacts on fertility. Future applications of miRNA biomarkers for precision medicine in diagnosing and managing endometriosis treatment are also discussed.

Upregulated Circular RNA hsa_circ_0008433 Regulates Pathogenesis in Endometriosis Via miRNA

circRNAs (circular RNAs) play important roles in the development of endometriosis. This study aimed to explore the functions of circRNAs on endometriosis. Two ectopic, two paired eutopic, and two normal endometrial tissue samples were collected for RNA-seq to obtain circRNA profiles and construct a circRNA-miRNA-mRNA network. The validation of 9 circRNAs in 15 patients was assessed by qRT-PCR. We selected hsa_circ_0008433 as the potential biomarker, followed by examining cell proliferation, colony formation, migration, angiopoiesis, cell cycle, and apoptosis. Furthermore, the expression of apoptosis-related proteins was detected using immunofluorescence (IF) and Western blotting. Bioinformatic analysis was used to select the potential target miRNA and genes of hsa_circ_0008433. A total of 209 upregulated and 117 downregulated differentially expressed circRNAs were identified from the eutopic and ectopic endometrial tissue samples. Eight circRNA levels were significantly increased in ectopic endometrial tissue sample compared with eutopic endometrial tissue. The hsa_circ_0008433 knockdown inhibited endometrial stromal cell proliferation, migration, colony formation, and angiopoiesis; promoted cell apoptosis; and downregulated Ki67 and PCNA expression levels. Moreover, the hsa_circ_0008433 knockdown increased Bax and E-CAD expression and decreased Bcl2, CDKN1B, and CyclinD1 levels. Ten potential target miRNAs of hsa_circ_0008433 were selected, and six of them occur significantly aberrant in hsa_circ_0008433-expressing cells. Increased hsa_circ_0008433 levels regulate epithelial mesenchymal transition (EMT) in endometriosis through the circRNA-miRNA-mRNA axis.

lncRNA PVT1/MicroRNA-17-5p/PTEN Axis Regulates Secretion of E2 and P4, Proliferation, and Apoptosis of Ovarian Granulosa Cells in PCOS

Recently, the roles of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) were identified in polycystic ovary syndrome (PCOS). In the present study, we investigated the role of the lncRNA PVT1/miR-17-5p/PTEN axis in PCOS ovarian granulosa cells. Expression of PVT1, miR-17-5p and PTEN in PCOS ovarian granulosa cells and follicular fluid was detected, and homeostatic model assessment of insulin resistance (HOMA-IR) and the levels of fasting plasma glucose (FPG), fasting insulin (FINS), and sex hormones were assessed. Then, the proliferation, apoptosis, and colony formation ability of ovarian granulosa cells were evaluated. The binding relationship between PVT1 and miR-17-5p as well as the target relationship between miR-17-5p and PTEN were determined by bioinformatics analysis, luciferase activity assay, RNA-induced silencing complex assay, and RNA pull-down assay. The levels of sex hormone-binding globulin and follicle-stimulating hormone were abated and the levels of luteinizing hormone, testosterone, FINS, FPG, and HOMA-IR were increased in PCOS serum. PVT1 and PTEN were overexpressed and miR-17-5p was reduced in PCOS ovarian granulosa cells and follicular fluid. Overexpressed miR-17-5p and inhibited PVT1 could decelerate apoptosis while accelerating colony formation ability and proliferation of ovarian granulosa cells in PCOS. Moreover, overexpression of PVT1 and reduced miR-17-5p could reverse these results. There existed target relation among PVT1, miR-17-5p, and PTEN, and PVT1 could inhibit miR-17-5p, thereby elevating PTEN. Our study suggests that inhibited PVT1 and overexpressed miR-17-5p result in downregulation of PTEN and promotion of cell proliferation, as well as inhibition of apoptosis of ovarian granulosa cells in PCOS.

Deciphering the Role of miRNAs in Endometriosis Pathophysiology Using Experimental Endometriosis Mouse Models

Endometriosis is an enigmatic disease for which we still have a poor understanding on how and why the disease develops. In recent years, miRNAs, small noncoding RNAs which regulate gene expression posttranscriptionally, have been evaluated for their role in endometriosis pathophysiology. This review will provide a brief summary on the role of miRNAs in endometrial physiology and pathophysiology as related to endometriosis. We will then discuss mouse models used in endometriosis research and the incorporation of some of these models in studies which examined the role of miRNAs in endometriosis pathophysiology. We conclude with providing future prospective on the role of mouse models in dissecting the role of miRNAs in endometriosis pathophysiology.

Interplay Between MicroRNAs and Oxidative Stress in Ovarian Conditions with a Focus on Ovarian Cancer and Endometriosis

Ovarian cancer and endometriosis are two distinct gynaecological conditions that share many biological aspects incuding proliferation, invasion of surrounding tissue, inflammation, inhibition of apoptosis, deregulation of angiogenesis and the ability to spread at a distance. miRNAs are small non-coding RNAs (19–22 nt) that act as post-transcriptional modulators of gene expression and are involved in several of the aforementioned processes. In addition, a growing body of evidence supports the contribution of oxidative stress (OS) to these gynaecological diseases: increased peritoneal OS due to the decomposition of retrograde menstruation blood facilitates both endometriotic lesion development and fallopian tube malignant transformation leading to high-grade serous ovarian cancer (HGSOC). Furthermore, as HGSOC develops, increased OS levels are associated with chemoresistance. Finally, continued bleeding within ovarian endometrioma raises OS levels and contributes to the development of endometriosis-associated ovarian cancer (EAOC). Therefore, this review aims to address the need for a better understanding of the dialogue between miRNAs and oxidative stress in the pathophysiology of ovarian conditions: endometriosis, EAOC and HGSOC.

miR-21a inhibits decidual cell apoptosis by targeting Pdcd4

Decidualization of endometrial stromal cells (ESCs) accompanied with embryo implantation is a key process in mammalian reproduction. Evidence suggests that maintenance of decidual cells function is essential. As a critical part in post-transcriptional gene regulation, microRNAs (miRNAs/miR) have been confirmed to be involved in decidualization. However, whether microRNAs regulate decidual cells function has not been reported. Aiming to clarify the role and potential mechanism of miRNAs in decidual cells, artificial induced decidualization model in mice was established. There are 94 differentially expressed miRNAs (≥two-fold change) between decidualized and non-decidualized tissues, including 60 upregulated and 34 downregulated miRNAs. Of the differentially expressed miRNAs, mmu-miR-21a is up-regulated. RT-qPCR also confirmed the up-regulation of mmu-miR-21a following decidualization in vivo and in vitro, and bioinformatic analysis and luciferase activity assay revealed Pdcd4 to be the target gene of mmu-miR-21a. Inhibition of mmu-miR-21a restrained secretory function of decidual cells induced by mESCs, accompanied with increase of Pdcd4 expression and resulted in the increase of cell apoptosis. In addition, we also determined the expression of hsa-miR-21 and Pdcd4 in human proliferative endometrial tissues and decidua tissues. hsa-miR-21 showed higher expression in human decidua tissues compared with proliferative endometrial tissues, while expression of Pdcd4 was contrary to that of hsa-miR-21. Similarly, cell apoptosis increased significantly in human endometrial stromal cell line in response to inhibition of hsa-miR-21. Collectively, we conclude that mmu-miR-21a/hsa-miR-21 may play a key role in regulating the function of decidual cells by inhibiting cell apoptosis through targeting Pdcd4.

Plasma miRNAs Display Limited Potential as Diagnostic Tools for Endometriosis

CONTEXT

Despite extensive searches for novel noninvasive diagnostics, laparoscopy remains the reference test for endometriosis. Circulating miRNAs are purported endometriosis biomarkers; however, the miRNA species and their diagnostic accuracy differ between studies and have not been validated in independent cohorts.

OBJECTIVE

Identify endometriosis-specific plasma miRNAs and determine their diagnostic test accuracy.

SETTING

Two university-based, public hospitals and a private gynecology practice in Australia.

DESIGN AND PARTICIPANTS

Four phases: (i) Explorative phase. Plasma miRNA menstrual cycle fluctuations were evaluated in women with endometriosis and asymptomatic controls (n = 16). (ii) Biomarker discovery. Endometriosis-specific plasma miRNAs were identified in (a) women with endometriosis and asymptomatic controls (n = 16) and (b) women with and without surgically defined endometriosis (n = 20). (iii) Biomarker selection. Plasma miRNAs with the best diagnostic potential for endometriosis were selected in a surgically defined selection cohort (n = 78). (iv) Biomarker validation. The diagnostic test accuracy of these miRNAs was calculated in an independent, surgically defined validation cohort (n = 119).

RESULTS

Forty-nine miRNAs were differentially expressed in women with endometriosis. Nine maintained dysregulation in the selection cohort, but only three (miR-155, miR574-3p and miR139-3p) did so in the validation cohort. Combined, these three miRNAs demonstrated a sensitivity and specificity of 83% and 51%, respectively.

CONCLUSION

Plasma miRNAs demonstrated modest sensitivity and specificity as diagnostic tests or triage tools for endometriosis. Other groups' findings were not replicated and accorded poorly with our results. Circulating miRNAs demonstrate diagnostic potential, but stringent, standardized methodological approaches are required for the development of a clinically applicable tool.

Non-coding RNAs in endometriosis: a narrative review

BACKGROUND

Endometriosis is a benign gynaecological disorder, which affects 10% of reproductive-aged women and is characterized by endometrial cells from the lining of the uterus being found outside the uterine cavity. However, the pathophysiological mechanisms causing the development of this heterogeneous disease remain enigmatic, and a lack of effective biomarkers necessitates surgical intervention for diagnosis. There is international recognition that accurate non-invasive diagnostic tests and more effective therapies are urgently needed. Non-coding RNA (ncRNA) molecules, which are important regulators of cellular function, have been implicated in many chronic conditions. In endometriosis, transcriptome profiling of tissue samples and functional in vivo and in vitro studies demonstrate that ncRNAs are key contributors to the disease process.

OBJECTIVE AND RATIONALE

In this review, we outline the biogenesis of various ncRNAs relevant to endometriosis and then summarize the evidence indicating their roles in regulatory pathways that govern disease establishment and progression.

SEARCH METHODS

Articles from 2000 to 2016 were selected for relevance, validity and quality, from results obtained in PubMed, MEDLINE and Google Scholar using the following search terms: ncRNA and reproduction; ncRNA and endometriosis; miRNA and endometriosis; lncRNA and endometriosis; siRNA and endometriosis; endometriosis; endometrial; cervical; ovary; uterus; reproductive tract. All articles were independently screened for eligibility by the authors.

OUTCOMES

This review integrates extensive information from all relevant published studies focusing on microRNAs, long ncRNAs and short inhibitory RNAs in endometriosis. We outline the biological function and synthesis of microRNAs, long ncRNAs and short inhibitory RNAs and provide detailed findings from human research as well as functional studies carried out both in vitro and in vivo, including animal models. Although variability in findings between individual studies exists, collectively, the extant literature justifies the conclusion that dysregulated ncRNAs are a significant element of the endometriosis condition.

WIDER IMPLICATIONS

There is a compelling case that microRNAs, long non-coding RNAs and short inhibitory RNAs have the potential to influence endometriosis development and persistence through modulating inflammation, proliferation, angiogenesis and tissue remodelling. Rapid advances in ncRNA biomarker discovery and therapeutics relevant to endometriosis are emerging. Unravelling the significance of ncRNAs in endometriosis will pave the way for new diagnostic tests and identify new therapeutic targets and treatment approaches that have the potential to improve clinical options for women with this disabling condition.

Circular RNAs are abundantly expressed and upregulated during repair of the damaged endometrium by Wharton's jelly-derived mesenchymal stem cells

BACKGROUND

Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) exhibit strong and powerful potential in repairing different diseases. The expression profile of circular RNA (circRNA) provides valuable insight for regulation of the repair process and exploration of reparative effect mechanisms.

METHODS

Human endometrial stromal cells (ESCs) were cultured with mifepristone to obtain damaged ESCs, which were then cocultured with or without WJ-MSCs (cocultured group versus non-cocultured group) to observe the reparative effect upon damaged ESCs by WJ-MSCs. CircRNA microarray was performed between the two groups. Based on the transcriptomics data, the differential gene expression profiles of the two groups were analyzed by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and network analysis methods. Screening of a circRNA database was performed, and the results were confirmed by quantitative polymerase chain reaction (qPCR).

RESULTS

WJ-MSCs exerted a reparative effect upon damaged ESCs in the cocultured group such as improved cell morphology, higher proliferative ability, and lower apoptosis rate. CircRNA array showed that 7757 circRNAs were differentially expressed in ESCs from the cocultured group. Mitotic cell cycle, cell cycle process, and nuclear division ranked top in the GO upregulated list of the two groups, while DNA replication and cell cycle ranked top in the KEGG pathway analysis upregulated list of the two groups. The nine most aberrantly expressed circRNAs were selected for further verification in the same cohort of samples by microarray analysis. Seven of the nine most aberrantly circRNAs were confirmed to be significantly upregulated in the cocultured group. And four of the seven circRNAs (hsa_circ_0015825, hsa-circRNA4049-38, hsa-circRNA5028-15, and hsa_circ_0111659) expression both in ESCs and WJ-MSCs tended to decrease with time by qPCR. The levels of the remaining three circRNAs (hsa-circRNA8881-21, hsa_circ_0020492 and hsa_circ_ 0026141) did not change significantly over time in either ESCs or WJ-MSCs. Moreover, we focused on hsa_circRNA_0111659 and predicted its miRNAs and targeted mRNA. The association of circRNA-miRNA-mRNA is likely to be involved in regulating the repair of endometrial damage.

CONCLUSIONS

Our results presented the abundant and upregulated circRNAs profile during repair of the damaged endometrium by WJ-MSCs and provided a novel perspective for circRNAs in the regulation of WJ-MSCs for endometrial repair.

Clotrimazole is effective for the regression of endometriotic implants in a Wistar rat experimental model of endometriosis

The present work aimed to evaluate molecular, angiogenic and inflammatory changes induced by clotrimazole (CTZ) on endometriosis lesions. For this, thirty female Wistar rats with surgically implanted autologous endometrium were treated with CTZ or vehicle (200 mg/kg) via esophageal gavage for 15 consecutive days. CTZ treatment significantly decreased the growth and the size of the implants, and histological examination indicated regression and atrophy, with no toxicity to the animals. The levels of the angiogenic markers VEGF and VEGFR-2 were significantly decreased in CTZ group. The treatment also promotes a reduction on PGE₂ and TNF-α levels. All these effects involve the amelioration of ERK1/2, Akt, AMPK and PERK signaling upon CTZ treatment. In conclusion, CTZ promoted an overall amelioration of endometriosis in a rat model due to the anti-angiogenic properties of the drug. Therefore, our results support the proposal of a clinical trial using CTZ for the treatment of endometriosis.

The miRNA Mirage: How Close Are We to Finding a Non-Invasive Diagnostic Biomarker in Endometriosis? A Systematic Review

Background: Endometriosis is a common disorder of the reproductive age group, characterised by the presence of ectopic endometrial tissue. The disease not only causes enormous suffering to the affected women, but also brings a tremendous medical and economic burden to bear on society. There is a long lag phase between the onset and diagnosis of the disease, mainly due to its non-specific symptoms and the lack of a non-invasive test. Endometriosis can only be diagnosed invasively by laparoscopy. A specific, non-invasive test to diagnose endometriosis is an unmet clinical need. The recent discovery of microRNAs (miRNAs) as modulators of gene expression, and their stability and specificity, make them an attractive candidate biomarker. Various studies on miRNAs in endometriosis have identified their cardinal role in the pathogenesis of the disease, and have proposed them as potential biomarkers in endometriosis. Rationale/Objectives: The aims of this review were to study the role of circulatory miRNAs in endometriosis, and bring to light whether circulatory miRNAs could be potential non-invasive biomarkers to diagnose the disease. Search methods: Three databases, PubMed, EMBASE, and BIOSIS were searched, using a combination of Mesh or Emtree headings and free-text terms, to identify literature relating to circulating miRNAs in endometriosis published from 1996 to 31 December 2017. Only peer-reviewed, full-text original research articles in English were included in the current review. The studies meeting the inclusion criteria were critically assessed and checked using the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies) tool. The dysregulated miRNAs were assessed regarding the concordance between the various studies and their role in the disease. Outcomes: Nine studies were critically analysed, and 42 different miRNAs were found to be dysregulated in them, with only one common miRNA (miR-20a) differentially expressed in more than one study. miR-17-5p/20a, miR-200, miR-199a, miR-143, and miR-145 were explored for their pivotal role in the aetiopathogenesis of endometriosis. Wider implications: It is emerging that miRNAs play a central role in the pathogenesis of endometriosis and have the potential of being promising biomarkers. Circulating miRNAs as a non-invasive diagnostic tool may shorten the delay in the diagnosis of the disease, thus alleviating the suffering of women and reducing the burden on health care systems. However, despite numerous studies on circulating miRNAs in endometriosis, no single miRNA or any panel of them seems to meet the criteria of a diagnostic biomarker. The disagreement between the various studies upholds the demand of larger, well-controlled systematic validation studies with uniformity in the research approaches and involving diverse populations.

Basic mechanisms of vascularization in endometriosis and their clinical implications

BACKGROUND

Vascularization is a major hallmark in the pathogenesis of endometriosis. An increasing number of studies suggests that multiple mechanisms contribute to the vascularization of endometriotic lesions, including angiogenesis, vasculogenesis and inosculation.

OBJECTIVE AND RATIONALE

In this review, we provide an overview of the basic mechanisms of vascularization in endometriosis and give special emphasis on their future clinical implications in the diagnosis and therapy of the disease.

SEARCH METHODS

Literature searches were performed in PubMed for English articles with the key words 'endometriosis', 'endometriotic lesions', 'angiogenesis', 'vascularization', 'vasculogenesis', 'endothelial progenitor cells' and 'inosculation'. The searches included both animal and human studies. No restriction was set for the publication date.

OUTCOMES

The engraftment of endometriotic lesions is typically associated with angiogenesis, i.e. the formation of new blood vessels from pre-existing ones. This angiogenic process underlies the complex regulation by angiogenic growth factors and hormones, which activate intracellular pathways and associated signaling molecules. In addition, circulating endothelial progenitor cells (EPCs) are mobilized from the bone marrow and recruited into endometriotic lesions, where they are incorporated into the endothelium of newly developing microvessels, referred to as vasculogenesis. Finally, preformed microvessels in shed endometrial fragments inosculate with the surrounding host microvasculature, resulting in a rapid blood supply to the ectopic tissue. These vascularization modes offer different possibilities for the establishment of novel diagnostic and therapeutic approaches. Angiogenic growth factors and EPCs may serve as biomarkers for the diagnosis and classification of endometriosis. Blood vessel formation and mature microvessels in endometriotic lesions may be targeted by means of anti-angiogenic compounds and vascular-disrupting agents.

WIDER IMPLICATIONS

The establishment of vascularization-based approaches in the management of endometriosis still represents a major challenge. For diagnostic purposes, reliable angiogenic and vasculogenic biomarker panels exhibiting a high sensitivity and specificity must be identified. For therapeutic purposes, novel compounds selectively targeting the vascularization of endometriotic lesions without inducing severe side effects are required. Recent progress in the field of endometriosis research indicates that these goals may be achieved in the near future.

Ginsenoside Rg3 Decreases Fibrotic and Invasive Nature of Endometriosis by Modulating miRNA-27b: In Vitro and In Vivo Studies

This research aimed to evaluate the potential therapeutic effects of Rg3 on endometriosis and identify target miRNAs. We designed an in vitro study using human endometrial stromal cells (HESCs) obtained from patients with endometriosis and an in vivo study using mouse models. HESCs were treated with Rg3-enhanced red ginseng extract (Rg3E); real-time PCR and microarray profiling, transfection, and western blot were performed. Mouse endometriosis models were developed and supplemented with Rg3E for 8 weeks. Gross lesion size and fibrotic character were analyzed in the mouse models. RNA levels of Ki-67, col-1, CTGF, fibronectin, TGF-β1, MMP2 and MMP9 significantly decreased in HESCs after Rg3E treatment. Microarray analysis revealed downregulation of miR-27b-3p, which is related to fibrosis modulation. Expression of miR-27b-3p was significantly higher in HESCs from patients with endometriosis than that of controls, and Rg3E treatment significantly decreased its expression; the contraction and migration assay revealed significant reductions in both fibrosis and migration potential in Rg3E-treated HESCs from endometriosis patients. A decrease in size and fibrotic character of endometrial lesions from the Rg3E groups was observed in vivo. In conclusion, Rg3 effectively altered fibrotic properties of HESCs from patients with endometriosis, which is likely associated with miR-27b-3p modulation.

Three-Dimensional Power Doppler Vascularization in Women With Ovarian Endometriomas and Relationship With Associated Painful Symptoms

OBJECTIVES

The objective of the study was to evaluate the correlation between endometrioma-associated pain and lesion vascularization as measured with 3-dimensional power Doppler transvaginal sonography.

METHODS

Endometriomas were examined, and 4 indices were obtained: mean grayness, flow index, vascularization index, and vascularization-flow index. Dysmenorrhea, chronic pelvic pain, and dyspareunia were analyzed in terms of severity, presence/absence, and duration.

RESULTS

Twenty-nine women were selected. The univariable association of painful symptoms in terms of presence/absence and duration was low with the exception of mean grayness with the presence of chronic pelvic pain (β = -0.106; P = .047; 95% confidence interval, 0.810 to 0.998). The R² value increased to 0.226 for dysmenorrhea (β = -0.475; P = .029) when analyzing the association between the vascularization index and the severity of painful symptoms. The visual analog scale scores for chronic pelvic pain and dyspareunia were higher (R²  = 0.300; β = -0.547 and -0.548, respectively; P = .028 and .053).

CONCLUSIONS

We observed an inverse association between the severity of pain and endometrioma vascularization. Further larger studies are required to confirm our findings.

miRNA‑34a‑5p downregulation of VEGFA in endometrial stem cells contributes to the pathogenesis of endometriosis

Endometrial-derived stem cells (EnSCs) serve an important role in the development of endometriosis via retrograde menstruation. Abnormal expression of miRNAs in EnSCs is involved in the etiology of endometriosis, however, the mechanisms remain unclear. The aim of the present study was to investigate the expression of miR‑34a‑5p and VEGFA in endometrial samples from patients with or without endometriosis, and then examine the underlying mechanism of microRNA‑34a‑5p regulation of VEGFA in EnSCs. Endometrial samples from patients with or without endometriosis were collected, and miR‑34a‑5p expression in the two groups was measured using RT‑PCR. Human endometrial‑derived stem cells (hEnSCs) were isolated from these endometrial samples, and hEnSCs were transfected with the miR‑34a‑5p mimics or control miRNAs. qPCR and western blotting were performed to assess the effects of miR‑34a‑5p on the expression of VEGFA in hEnSCs, and cell growth was assessed by an MTT assay. miR‑34a‑5p was significantly downregulated in patients with endometriosis when compared with that of those without endometriosis. VEGFA expression levels in hEnSCs with an overexpression of miR‑34a‑5p were significantly reduced when compared with those in the negative control (P<0.01). In addition, the upregulation of miR‑34a‑5p suppressed EnSCs proliferation by targeting the 3' untranslated region of VEGFA. miR‑34a‑5p provides a novel avenue for the understanding of the development of endometriosis, and may facilitate the development of potential therapeutics against endometriosis.

MicroRNAs and Endometriosis: Distinguishing Drivers from Passengers in Disease Pathogenesis

Endometriosis is a disease common in women of reproductive age, characterized by pelvic pain and infertility. Despite its prevalence, the factors and mechanisms which contribute to the development and survival of ectopic lesions remain uncertain. MicroRNAs (miRNAs) are small RNA molecules that regulate posttranscriptional gene regulation which have been proposed to contribute to the pathogenesis of many diseases including that of endometriosis. This review summarizes the results of initial studies describing differentially expressed miRNAs between endometriotic lesion tissue and eutopic endometrium. Focus then moves toward discussion of studies on examining function of differentially expressed miRNAs to determine if they play a permissive role (driver of the disease) in events conducive to endometriosis progression/survival. Included in this discussion are the potential targets of these miRNAs and how their mis-expression may contribute to the disease. Limitations and challenges faced in studying miRNAs and endometriosis pathogenesis and recommendations to overcome these hurdles are presented at the end.

Differential micro ribonucleic acid expression profiling in ovarian endometrioma with leuprolide acetate treatment

AIM

Micro ribonucleic acids (miRNAs) play an important pathological role in endometriosis. Leuprolide acetate, an analog of gonadotropin-releasing hormone, is widely used to treat endometriosis; however, the molecular mechanisms involved in endometriotic tissue regression remain unclear. We performed miRNA expression profiling of clinical ovarian endometrioma to obtain insight into the effects of leuprolide acetate treatment.

METHODS

We obtained clinical samples from nine normal eutopic endometrium, eight ovarian endometriotic, and 12 leuprolide acetate-treated endometriotic tissues. We compared the miRNA expression profiles of the three groups by performing TaqMan Array MicroRNA Card and bioinformatic analysis.

RESULTS

Two miRNAs, miR-939 and miR-154, were upregulated in endometriotic tissue and downregulated in leuprolide acetate-treated endometriotic tissue. Five miRNAs (miR-146a, miR-142-3p, miR-136*, miR-125b-1* and miR-15b*) were unchanged in endometriotic tissue but were upregulated under leuprolide acetate treatment. Ingenuity pathway analysis using predicted target genes for the seven identified miRNAs suggested the involvement of a range of pathways, including axonal guidance, bone morphogenetic protein, phosphatase and tensin homolog and nitric oxide signaling; molecular mechanisms of cancer; and the adipogenesis and signal transducer and activator of transcription 3 (STAT3) pathways.

CONCLUSIONS

To our knowledge, this is the first report profiling the miRNAs of endometrioma under leuprolide acetate treatment. The expression of seven miRNAs was modulated, concomitant with the disease state. This result gives new insight into the effects of leuprolide acetate treatment. Further investigation using quantitative reverse transcriptase-polymerase chain reaction and immunohistochemistry will allow us to validate the results of this study and to explore new therapeutic targets and biomarkers of endometriosis.

miR-196a overexpression activates the MEK/ERK signal and represses the progesterone receptor and decidualization in eutopic endometrium from women with endometriosis

STUDY QUESTION

Do microRNAs (miRNAs) contribute to aberrant progesterone receptor (PGR) expression in the eutopic endometrium of women with endometriosis? SUMMARY ANSWER: miR-196a upregulates MEK/ERK signalling, mediating a downregulation of PGR expression in the eutopic endometrium of women with minimal or mild endometriosis.

WHAT IS KNOWN ALREADY

Implantation failure is strongly suggested as an underlying cause for the observed infertility in minimal or mild endometriosis. Progesterone resistance, which is mainly caused by aberrantly expressed progesterone receptor in the eutopic endometrium, is considered as a key factor of decreased endometrial receptivity; thus far, epigenetics, but not miRNA, has been shown to affect PGR expression in the endometrium.

STUDY DESIGN SIZE, DURATION

Microarray analysis was used to analyse the eutopic endometrium. The differential expression of miR-196a was validated. Bioinformatics analysis predicted that miR-196a targets the 3'-untranslated region (UTR) of the PGR. The relationship between the miR-196a level and PGR expression was studied and the role of the MEK/ERK signal pathway was investigated.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Total RNA was extracted from eutopic endometrium samples in three infertile women with mild/minimal endometriosis and three disease-free control subjects. The miRNA and mRNA expression levels were analysed by microarray analysis. The miR-196a expression was validated by qRT-PCR [endometriosis (n = 22) and control (n = 20)], while functional analysis utilised in vitro transfection of endometrial stromal cells (ESCs), induction of decidualization of ESCs, and luciferase reporter assays in 293 T cell lines.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 66 dysregulated miRNAs and 357 dysregulated mRNAs were screened by microarray analysis. miR-196a and P-MEK/P-ERK were both found to be significantly upregulated in the eutopic endometrium in patients with mild/minimal endometriosis. PGR and PGR-B mRNA were inhibited by miR-196a overexpression and upregulated by miR-196a inhibition. Luciferase reporter failed to confirm the target regulation of miR-196a on PGR. Transfection of ESCs with a miR-196a mimic led to an increase in the P-MEK/P-ERK protein levels, decrease in the PGR protein levels, and atypical decidualization. Following miR-196a inhibition, the P-MEK/P-ERK protein was downregulated and the PGR protein was upregulated. Inhibition of P-MEK/P-ERK also increased PGR expression.

LARGE SCALE DATA

Data are presented in Supplementary Tables SI and SII.

LIMITATIONS REASONS FOR CAUTION

This study focused on the role of miR-196a, and therefore does not involve other miRNAs; hence, it is possible that other miRNAs may also be responsible for progestin resistance in endometriosis.

WIDER IMPLICATIONS OF THE FINDINGS

Our data revealed altered miRNA expression and activated MEK/ERK signalling in the eutopic endometrium in minimal or mild endometriosis. We showed that the miR-196a level is associated with reduced expression of PGR isoforms through MEK/ERK, suggesting that miR-196a and MEK/ERK are both potential biomarkers of endometriosis. These results provide a novel approach to target the mechanisms behind progesterone resistance in endometriosis.

STUDY FUNDING/COMPETING INTERESTS

This research was supported by the National Natural Science Foundation of China (No. 81370693). The authors have no conflicts of interest.

Insights into the Regulatory Role of Non-coding RNAs in Cancer Metabolism

Cancer represents a complex disease originated from alterations in several genes leading to disturbances in important signaling pathways in tumor biology, favoring heterogeneity that promotes adaptability and pharmacological resistance of tumor cells. Metabolic reprogramming has emerged as an important hallmark of cancer characterized by the presence of aerobic glycolysis, increased glutaminolysis and fatty acid biosynthesis, as well as an altered mitochondrial energy production. The metabolic switches that support energetic requirements of cancer cells are closely related to either activation of oncogenes or down-modulation of tumor-suppressor genes, finally leading to dysregulation of cell proliferation, metastasis and drug resistance signals. Non-coding RNAs (ncRNAs) have emerged as one important kind of molecules that can regulate altered genes contributing, to the establishment of metabolic reprogramming. Moreover, diverse metabolic signals can regulate ncRNA expression and activity at genetic, transcriptional, or epigenetic levels. The regulatory landscape of ncRNAs may provide a new approach for understanding and treatment of different types of malignancies. In this review we discuss the regulatory role exerted by ncRNAs on metabolic enzymes and pathways involved in glucose, lipid, and amino acid metabolism. We also review how metabolic stress conditions and tumoral microenvironment influence ncRNA expression and activity. Furthermore, we comment on the therapeutic potential of metabolism-related ncRNAs in cancer.

Molecular cloning, expression analysis and miRNA prediction of vascular endothelial growth factor A (VEGFAa and VEGFAb) in pond loach Misgurnus anguillicaudatus, an air-breathing fish

Vascular endothelial growth factor A (VEGFA) is the most studied and the best characterized member of the VEGF family and is a key regulator of angiogenesis via its ability to affect the proliferation, migration, and differentiation of endothelial cells. In this study, the full-length cDNAs encoding VEGFAa and VEGFAb from pond loach, Misgurnus anguillicaudatus, were isolated. The VEGFAa is constituted by an open reading frame (ORF) of 570bp encoding for a peptide of 189 amino acid residues, a 639bp 5'-untranslated region (UTR) and a 2383bp 3' UTR. The VEGFAb is constituted by an ORF of 687bp encoding for a peptide of 228 amino acid residues, a 560bp 5' UTR and a 1268bp 3' UTR. Phylogenetic analysis indicated that the VEGFAa and VEGFAb of pond loach were conserved in vertebrates. Expression levels of VEGFAa and VEGFAb were detected by RT-qPCR at different development stages of pond loach and in different tissues of 6-month-old, 12-month-old and 24-month-old pond loach. Moreover, eight predicted miRNAs (miR-200, miR-29, miR-218, miR-338, miR-103, miR-15, miR-17 and miR-223) targeting VEGFAa and VEGFAb were validated by an intestinal air-breathing inhibition experiment. This study will be of value for further studies into the function of VEGFA and its corresponding miRNAs, which will shed a light on the vascularization and accessory air-breathing process in pond loach.

Estrogen Stimulates Homing of Endothelial Progenitor Cells to Endometriotic Lesions

The incorporation of endothelial progenitor cells (EPCs) into microvessels contributes to the vascularization of endometriotic lesions. Herein, we analyzed whether this vasculogenic process is regulated by estrogen. Estrogen- and vehicle-treated human EPCs were analyzed for migration and tube formation. Endometriotic lesions were induced in irradiated FVB/N mice, which were reconstituted with bone marrow from FVB/N-TgN (Tie2/green fluorescent protein) 287 Sato mice. The animals were treated with 100 μg/kg β-estradiol 17-valerate or vehicle (control) over 7 and 28 days. Lesion growth, cyst formation, homing of green fluorescent protein(+)/Tie2(+) EPCs, vascularization, cell proliferation, and apoptosis were analyzed by high-resolution ultrasonography, caliper measurements, histology, and immunohistochemistry. Numbers of blood circulating EPCs were assessed by flow cytometry. In vitro, estrogen-treated EPCs exhibited a higher migratory and tube-forming capacity when compared with controls. In vivo, numbers of circulating EPCs were not affected by estrogen. However, estrogen significantly increased the number of EPCs incorporated into the lesions' microvasculature, resulting in an improved early vascularization. Estrogen further stimulated the growth of lesions, which exhibited massively dilated glands with a flattened layer of stroma. This was mainly because of an increased glandular secretory activity, whereas cell proliferation and apoptosis were not markedly affected. These findings indicate that vasculogenesis in endometriotic lesions is dependent on estrogen, which adds a novel hormonally regulated mechanism to the complex pathophysiology of endometriosis.

Endometrial biomarkers for the non-invasive diagnosis of endometriosis

BACKGROUND

About 10% of reproductive-aged women suffer from endometriosis, which is a costly, chronic disease that causes pelvic pain and subfertility. Laparoscopy is the gold standard diagnostic test for endometriosis, but it is expensive and carries surgical risks. Currently, there are no non-invasive tests available in clinical practice that accurately diagnose endometriosis. This is the first diagnostic test accuracy review of endometrial biomarkers for endometriosis that utilises Cochrane methodologies, providing an update on the rapidly expanding literature in this field.

OBJECTIVES

To determine the diagnostic accuracy of the endometrial biomarkers for pelvic endometriosis, using a surgical diagnosis as the reference standard. We evaluated the tests as replacement tests for diagnostic surgery and as triage tests to inform decisions to undertake surgery for endometriosis.

SEARCH METHODS

We did not restrict the searches to particular study designs, language or publication dates. To identify trials, we searched the following databases: CENTRAL (2015, July), MEDLINE (inception to May 2015), EMBASE (inception to May 2015), CINAHL (inception to April 2015), PsycINFO (inception to April 2015), Web of Science (inception to April 2015), LILACS (inception to April 2015), OAIster (inception to April 2015), TRIP (inception to April 2015) and ClinicalTrials.gov (inception to April 2015). We searched DARE and PubMed databases up to April 2015 to identify reviews and guidelines as sources of references to potentially relevant studies. We also performed searches for papers recently published and not yet indexed in the major databases. The search strategies incorporated words in the title, abstract, text words across the record and the medical subject headings (MeSH).

SELECTION CRITERIA

We considered published peer-reviewed, randomised controlled or cross-sectional studies of any size that included prospectively collected samples from any population of reproductive-aged women suspected of having one or more of the following target conditions: ovarian, peritoneal or deep infiltrating endometriosis (DIE).

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from each study and performed a quality assessment. For each endometrial diagnostic test, we classified the data as positive or negative for the surgical detection of endometriosis and calculated the estimates of sensitivity and specificity. We considered two or more tests evaluated in the same cohort as separate data sets. We used the bivariate model to obtain pooled estimates of sensitivity and specificity whenever sufficient data were available. The predetermined criteria for a clinically useful test to replace diagnostic surgery was one with a sensitivity of 94% and a specificity of 79%. The criteria for triage tests were set at sensitivity at or above 95% and specificity at or above 50%, which in case of negative results rules out the diagnosis (SnOUT test) or sensitivity at or above 50% with specificity at or above 95%, which in case of positive result rules in the diagnosis (SpIN test).

MAIN RESULTS

We included 54 studies involving 2729 participants, most of which were of poor methodological quality. The studies evaluated endometrial biomarkers either in specific phases of the menstrual cycle or outside of it, and the studies tested the biomarkers either in menstrual fluid, in whole endometrial tissue or in separate endometrial components. Twenty-seven studies evaluated the diagnostic performance of 22 endometrial biomarkers for endometriosis. These were angiogenesis and growth factors (PROK-1), cell-adhesion molecules (integrins α3β1, α4β1, β1 and α6), DNA-repair molecules (hTERT), endometrial and mitochondrial proteome, hormonal markers (CYP19, 17βHSD2, ER-α, ER-β), inflammatory markers (IL-1R2), myogenic markers (caldesmon, CALD-1), neural markers (PGP 9.5, VIP, CGRP, SP, NPY, NF) and tumour markers (CA-125). Most of these biomarkers were assessed in single studies, whilst only data for PGP 9.5 and CYP19 were available for meta-analysis. These two biomarkers demonstrated significant diversity for the diagnostic estimates between the studies; however, the data were too limited to reliably determine the sources of heterogeneity. The mean sensitivities and specificities of PGP 9.5 (7 studies, 361 women) were 0.96 (95% confidence interval (CI) 0.91 to 1.00) and 0.86 (95% CI 0.70 to 1.00), after excluding one outlier study, and for CYP19 (8 studies, 444 women), they were were 0.77 (95% CI 0.70 to 0.85) and 0.74 (95% CI 0.65 to 84), respectively. We could not statistically evaluate other biomarkers in a meaningful way. An additional 31 studies evaluated 77 biomarkers that showed no evidence of differences in expression levels between the groups of women with and without endometriosis.

AUTHORS' CONCLUSIONS

We could not statistically evaluate most of the biomarkers assessed in this review in a meaningful way. In view of the low quality of most of the included studies, the findings of this review should be interpreted with caution. Although PGP 9.5 met the criteria for a replacement test, it demonstrated considerable inter study heterogeneity in diagnostic estimates, the source of which could not be determined. Several endometrial biomarkers, such as endometrial proteome, 17βHSD2, IL-1R2, caldesmon and other neural markers (VIP, CGRP, SP, NPY and combination of VIP, PGP 9.5 and SP) showed promising evidence of diagnostic accuracy, but there was insufficient or poor quality evidence for any clinical recommendations. Laparoscopy remains the gold standard for the diagnosis of endometriosis, and using any non-invasive tests should only be undertaken in a research setting. We have also identified a number of biomarkers that demonstrated no diagnostic value for endometriosis. We recommend that researchers direct future studies towards biomarkers with high diagnostic potential in good quality diagnostic studies.

MicroRNA Profiles in Spontaneous Decidualized Menstrual Endometrium and Early Pregnancy Decidua with Successfully Implanted Embryos

To comparatively analyze the human microRNA (miRNA) profiles between spontaneous decidualized menstrual endometrium and early pregnancy decidua by an in-depth sequencing of miRNAs. The specific miRNAs expressed at conception might be involved in pregnancy establishment and expression of let-7f-5p and let-7g-5p was experimentally up-regulated or inhibited to assess the effect on the expression of IGF2BP-1 and IGF2R in vitro, respectively. Samples of endometria and deciduas were obtained from 25 women who suffered from tubal or male factor subfertility and from 35 early pregnant women who underwent pregnancy termination at 6–8 weeks gestation were irrespectively collected and comparatively analyzed by miRNA sequencing and differential expression of known and novel miRNAs was analyzed using bioinformatics. The 2042 miRNA expression was analyzed in the study and the differential expression of six miRNAs was validated by qRT-PCR. The expression of four miRNAs in decidua samples was down-regulated (miR-34c, miR-92a, miR-181a-5p, and miR-191), whereas the expression of miR-10a-5p and let-7f-5p was significantly up-regulated. The expression of IGF2BP-1 and IGF2R declined and increased with overexpression and inhibition of let-7f-5p and let-7g-5p, respectively. Changes in the expression of particular miRNAs might play a role in the physiology of decidualization following successful embryo implantation, ultimately resulting in continuous decidualization.

Non-coding RNAs in Uterine Development, Function and Disease

The major function of the uterus is to accept and provide a suitable environment for an embryo, ultimately leading the birth of offspring and successful propagation of the species. For this occur, there must be precise coordination of hormonal signalling within both the endometrial and myometrial components of this organ. Non-coding RNAs, specifically, microRNAs (miRNAs) have been shown to be essential for normal uterine development and function. Within this organ, miRNAs are proposed to fine-tune the actions of the female steroid hormones estradiol and progesterone. Not surprising, mis-expression of miRNAs has been documented in diseases of the endometrium and myometrium such as endometriosis and leiomyomas, respectively. In this chapter, I will review the current understanding on the role, regulation and function of non-coding RNAs focusing on miRNAs in both the normal physiology of the endometrium and myometrium as well as in pathologies of these tissues, namely endometriosis and leiomyomas.