MicroRNA expression profiling of eutopic secretory endometrium in women with versus without endometriosis

Molecular signature of eutopic endometrium in endometriosis based on the multi-omics integrative synthesis

PURPOSE

To synthesise data from genome-wide studies reporting molecular signature of eutopic endometrium through the phases of the menstrual cycle in endometriosis.

METHODS

Extraction of data from publications reporting genetic signatures characterising endometrium associated with endometriosis. The nomenclature of extracted differentially expressed transcripts and proteins was adopted according to the HUGO Gene Nomenclature Committee (HGNC). Loci were further sorted according to the different phases of the menstrual cycle, i.e. menstrual (M), proliferative (P), secretory (S), early-secretory (ES), mid-secretory (MS), late-secretory (LS), and not specified (N/S) if the endometrial dating was not available. Enrichment analysis was performed using the DAVID bioinformatics tool.

RESULTS

Altered molecular changes were reported by 21 studies, including 13 performed at the transcriptomic, 6 at proteomic, and 2 at epigenomic level. Extracted data resulted in a catalogue of total 670 genetic causes with available 591 official gene symbols, i.e. M = 3, P = 188, S = 81, ES = 82, MS = 173, LS = 36, and N/S = 28. Enriched pathways included oestrogen signalling pathway, extracellular matrix organization, and endothelial cell chemotaxis. Our study revealed that knowledge of endometrium biology in endometriosis is fragmented due to heterogeneity of published data. However, 15 genes reported as dysregulated by at least two studies within the same phase and 33 significantly enriched GO-BP terms/KEGG pathways associated with different phases of the menstrual cycle were identified.

CONCLUSIONS

A multi-omics insight into molecular patterns underlying endometriosis could contribute towards identification of endometrial pathological mechanisms that impact fertility capacities of women with endometriosis.

Seminal Plasma Modulates miRNA Expression by Sow Genital Tract Lining Explants

The seminal plasma (SP) modulates the female reproductive immune environment after mating, and microRNAs (miRNAs) could participate in the process. Considering that the boar ejaculate is built by fractions differing in SP-composition, this study evaluated whether exposure of mucosal explants of the sow internal genital tract (uterus, utero-tubal junction and isthmus) to different SP-fractions changed the profile of explant-secreted miRNAs. Mucosal explants retrieved from oestrus sows (n = 3) were in vitro exposed to: Medium 199 (M199, Control) or M199 supplemented (1:40 v/v) with SP from the sperm-rich fraction (SRF), the post-SRF or the entire recomposed ejaculate, for 16 h. After, the explants were cultured in M199 for 24 h to finally collect the media for miRNA analyses using GeneChip miRNA 4.0 Array (Affymetrix). Fifteen differentially expressed (False Discovery Rate (FDR) < 0.05 and Fold-change ≥ 2) miRNAs (11 down- versus 4 up-regulated) were identified (the most in the media of uterine explants incubated with SP from post-SRF). Bioinformatics analysis identified that predicted target genes of dysregulated miRNAs, mainly miR-34b, miR-205, miR-4776-3p and miR-574-5p, were involved in functions and pathways related to immune response. In conclusion, SP is able to elicit changes in the miRNAs profile secreted by female genital tract, ultimately depending SP-composition.

MicroRNA‑16 inhibits endometrial stromal cell migration and invasion through suppression of the inhibitor of nuclear factor‑κB kinase subunit β/nuclear factor‑κB pathway

Accumulating evidence has demonstrated that endometrial stromal cells (ESCs) are responsible for the pathogenesis of endometriosis (Ems), which is characterized by the presence of functional endometrial-like tissues outside the uterine cavity. Abnormal expression of microRNAs (miRNAs) in ESCs may be implicated in the etiology of Ems; however, the exact mechanisms have yet to be fully elucidated. The aim of the present study was to investigate the effects of miRNAs on ESCs and the underlying mechanisms. Using a microarray assay, microRNA-16 (miR-16) was found to be significantly downregulated in the ectopic endometrial tissues in patients with Ems, compared with that in eutopic endometrial tissues. Overexpression of miR-16 significantly suppressed the migration and invasion of ESCs, whereas miR-16 inhibition exerted the opposite effects. Furthermore, dual luciferase reporter assay demonstrated that miR-16 directly targeted the inhibitor of nuclear factor (NF)-κB kinase subunit β (IKKβ) and suppressed its translation. It was observed that the expression of IKKβ was upregulated and inversely correlated with miR-16 levels in the ectopic endometrial tissues in patients with Ems. Additionally, knockdown of IKKβ by si-IKKβ mimicked the effects of miR-16 overexpression on ESCs, while the promoting effects of IKKβ overexpression on the migration and invasion of ESCs were attenuated by miR-16 overexpression. Finally, miR-16 inhibited the activation of the NF-κB pathway by targeting IKKβ. Collectively, these results demonstrated that miR-16 may suppress Ems by inhibiting the IKKβ/NF-κB pathway, suggesting that miR-16 may be a useful target in the treatment of Ems.

Endometrial microRNAs and their aberrant expression patterns

MicroRNAs (miRNAs) are a class of small noncoding RNAs that regulate gene expression. They play fundamental roles in several biological processes, including cell differentiation and proliferation, embryo development, organ development, and organ metabolism. Besides regulating the physiological processes, miRNAs regulate various pathological conditions such as tumors, metastases, metabolic diseases, and osteoporosis. Although several studies have been performed on miRNAs, only few studies have described the miRNA expression and functions in human reproductive tract tissues. During menstruation, the human endometrium undergoes extensive cyclic morphological and biochemical modifications before embryo implantation. In addition to the ovarian steroid hormones (estrogen and progesterone), endometrial autocrine or paracrine factors and embryo-derived signals play a significant role in endometrial functions. miRNAs are considered key regulators of gene expression in the human endometrium and implantation process, and their aberrant expression levels are associated with the development of various disorders, including tumorigenesis. In this review, we summarize the studies that show the role of miRNAs in regulating the physiological conditions of the endometrium and the implantation process and discuss the aberrant expression of miRNAs in ectopic pregnancy, endometriosis, and endometrial cancer.

Endometriosis research in the -omics era

Endometriosis is a pathological condition extensively studied, but its pathogenesis is not completely understood, since its pathophysiology stems from a broad spectrum of environmental influences and genetic factors. Moreover, the nature of this condition is heterogeneous and includes different anatomical entities. Scientists actively pursue discovery of novel biomarkers in the hope of better identifying susceptible individuals in early stages of the disease. High-throughput technologies have substantially revolutionized medical research and, as a first step, the advent of genotyping arrays led to large-scale genome-wide association studies (GWAS) and enabled the assessment of global transcript levels, thus giving rise to integrative genetics. In this framework, comprehensive studies have been conducted at multiple biological levels by using the "omics" platforms, thus allowing to re-examine endometriosis at a greater degree of molecular resolution. -Omics technologies can detect and analyze hundreds of markers in the same experiment and their increasing use in the field of gynecology comes from an urgent need to find new diagnostic and therapeutic tools that improve the diagnosis of endometriosis and the efficacy of assisted reproductive techniques. Proteomics and metabolomics have been introduced recently into the every day methodology of researchers collaborating with gynecologists and, importantly, multi-omics approach is advantageous to gain insight of the total information that underlies endometriosis, compared to studies of any single -omics type. In this review, we expect to present multiple studies based on the high-throughput-omics technologies and to shed light in all considerable advantages that they may confer to a proper management of endometriosis.

Apoptotic functions of microRNAs in pathogenesis, diagnosis, and treatment of endometriosis

MicroRNAs or miRNAs are a component of the non-coding RNAs family which is engaged in many cellular functions such as cell proliferation, apoptosis, gene expression, signaling pathways, angiogenesis, and etc. Endometriosis is a malignant gynecologic disorder occurring in women before menopausal age. Pathogenesis of this illness is still a discussion subject between the scientists but in our knowledge, microRNAs can be one of the possible involved factors. The purpose of this paper is to investigate the role of apoptotic activities of miRNAs in endometriosis. Accumulative evidence has demonstrated the role of cell proliferation, apoptosis, and invasion in the progression of these diseases. In this review, we looked into the specific role of apoptosis and its related genes and pathways in endometriosis and tied to present an explanation of how miRNAs can affect endometriosis by their apoptotic activities. What we found is that a great extent of miRNAs is involved in this illness and they are responsible for repressing apoptosis and progression of the disease. As a result, miRNAs have two different usages in endometriosis: biomarkers and potential therapeutic targets. In this review we gathered a great amount of evidence to inquire into the role of micro RNAs in inducing apoptosis and how this mechanism can be exerted for therapeutic purposes for endometriosis.

Dysregulation of miR-202-3p Affects Migration and Invasion of Endometrial Stromal Cells in Endometriosis via Targeting ROCK1

Dysregulation of microRNAs in endometrial cells plays a pivotal role in the pathogenesis of endometriosis (EM). This study aims to investigate the implication of aberrant miR-202-3p expression in EM and the underlying mechanisms. We demonstrated that miR-202-3p was significantly downregulated in eutopic endometrium of EM in comparison to normal endometrial samples (P < 0.05). Primary endometrial stromal cells (ESCs) isolated from eutopic or ectopic endometrium also showed a significant decrease in miR-202-3p level compared to ESCs from normal endometrium (P < 0.01). Functional studies using MTT, wound healing assay and transwell assay indicated that overexpression of miR-202-3p greatly impaired cell viability, migration, and invasion, whereas suppression of miR-202-3p exhibited the opposite effects (P < 0.05 or P < 0.01). miR-202-3p mimics or inhibitors transfection significantly decreased or increased expression of Rho-associated, coiled-coil containing protein kinase 1 (ROCK1), respectively, in ESCs (P < 0.01). Using dual luciferase reporter assay, we validated ROCK1 as a direct target of miR-202-3p. Moreover, negative correlations between miR-202-3p and ROCK1 mRNA/protein levels were determined in both eutopic and normal control endometrium (P < 0.01). In conclusion, these findings suggest that suppression of miR-202-3p in ESCs results in enhanced cell viability, invasion, and migration at least partially via upregulation of its target ROCK1, which eventually contributes to the development of endometriosis.

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.

The Pathogenesis of Endometriosis: Molecular and Cell Biology Insights

The etiopathogenesis of endometriosis is a multifactorial process resulting in a heterogeneous disease. Considering that endometriosis etiology and pathogenesis are still far from being fully elucidated, the current review aims to offer a comprehensive summary of the available evidence. We performed a narrative review synthesizing the findings of the English literature retrieved from computerized databases from inception to June 2019, using the Medical Subject Headings (MeSH) unique ID term "Endometriosis" (ID:D004715) with "Etiology" (ID:Q000209), "Immunology" (ID:Q000276), "Genetics" (ID:D005823) and "Epigenesis, Genetic" (ID:D044127). Endometriosis may origin from Müllerian or non-Müllerian stem cells including those from the endometrial basal layer, Müllerian remnants, bone marrow, or the peritoneum. The innate ability of endometrial stem cells to regenerate cyclically seems to play a key role, as well as the dysregulated hormonal pathways. The presence of such cells in the peritoneal cavity and what leads to the development of endometriosis is a complex process with a large number of interconnected factors, potentially both inherited and acquired. Genetic predisposition is complex and related to the combined action of several genes with limited influence. The epigenetic mechanisms control many of the processes involved in the immunologic, immunohistochemical, histological, and biological aberrations that characterize the eutopic and ectopic endometrium in affected patients. However, what triggers such alterations is not clear and may be both genetically and epigenetically inherited, or it may be acquired by the particular combination of several elements such as the persistent peritoneal menstrual reflux as well as exogenous factors. The heterogeneity of endometriosis and the different contexts in which it develops suggest that a single etiopathogenetic model is not sufficient to explain its complex pathobiology.

Association study of AGO1 and AGO2 genes polymorphisms with recurrent pregnancy loss

An Argonaute (AGO) protein within the RNA-induced silencing complex binds a microRNA, permitting the target mRNA to be silenced. We hypothesized that variations in AGO genes had the possibility including affected the miRNA function and associated with recurrent pregnancy loss (RPL) susceptibility. Especially, we were chosen the AGO1 (rs595961, rs636832) and AGO2 (rs2292779, rs4961280) polymorphisms because of those polymorphisms have already reported in other diseases excluding the RPL. Here, we conducted a case-control study (385 RPL patients and 246 controls) to evaluate the association of four polymorphisms with RPL. We found that the AGO1 rs595961 AA genotype, recessive model (P = 0.039; P = 0.043, respectively), the AGO1 rs636832 GG genotype, and recessive model (P = 0.037; P = 0.016, respectively) were associated with RPL in women who had had four or more consecutive pregnancy losses. The patients with the AGO1 rs636832 GG genotypes had greater platelet counts (P = 0.023), while the patients with the AGO2 rs4961280 CA genotypes had less homocysteine (P = 0.027). Based on these results, we propose that genetic variations with respect to the AGO1 and AGO2 genotypes are associated with risk for RPL, and might serve as useful biomarkers for the prognosis of RPL.

Reduced microRNA-451 expression in eutopic endometrium contributes to the pathogenesis of endometriosis

BACKGROUND

Endometriosis (EMs) is a chronic and recurrent, but benign, disease in women of reproductive age, and EMs patients have a high risk of developing gynecological tumors and autoimmune disorders. The etiology of EMs is not clear. Certain genetic markers in the eutopic endometrium are key in the pathogenesis of EMs. MicroRNAs (miRNAs) are implicated in several biological processes, such as cell proliferation, differentiation, and apoptosis. MiR-451 is interesting, as it acts as a tumor suppressor and is relevant to the poor prognosis of cancers.

AIM

To evaluate the expression levels and role of miR-451 in the eutopic endometrium and predict possible targets of miR-451 and related signaling pathways.

METHODS

Quantitative real-time polymerase chain reaction was used to evaluate miR-451 expression in cultured cell lines as well as in pathologic tissues from 40 patients with EMs and 20 donors with no history of the disease (controls). Cell Counting Kit-8 and flow cytometric assays were performed to determine cell proliferation and survival rates after transfection with miR-451 mimics and siRNAs. MiR-451 targets were predicted using miRDB and miRcode target-predicting databases.

RESULTS

We observed lower miR-451 levels in eutopic endometrial tissues from patients with EMs than in control tissues, and this difference was not related to the American Society for Reproductive Medicine stage. Ectopic overexpression of miR-451 in eutopic cells induced apoptosis and inhibited cell proliferation. SiRNA-mediated miR-451 knockdown reversed these effects. Using miRDB and miRcode, we identified 12 potential miR-451 target genes. We hypothesize that the expression of YWHAZ, OSR1, TTN, and CDKN2D may be regulated by miR-451 and be involved in disease pathogenesis.

CONCLUSION

Reduced miR-451 expression in the eutopic endometrium contributes to the pathogenesis of EMs by promoting cell proliferation and reducing apoptosis. Thus, miR-451 is a novel biomarker for EMs. YWHAZ, OSR1, TTN, and CDKN2D are potential target genes of miR-451 and may have key roles in this disease.

miR-451a Inhibition Reduces Established Endometriosis Lesions in Mice

Endometriosis is an estrogen-dependent pro-inflammatory disease that affects 6% to 10% of reproductive-age women. Current treatments target sex steroids, and none are disease-specific. MicroRNA treatments have provided promising results for some chronic diseases and cancers. We have previously shown microRNA 451a is increased in endometriosis and that elevation of 451a contributes to the pathophysiology of the disease. Here, we propose inhibition of miR-451a for the treatment of endometriosis in a murine model. Endometriosis was treated using a microRNA 451a inhibitor or a scrambled control microRNA. Treatment with miR-451a inhibitor resulted in reduced endometriosis lesion size (30 vs 13 mm³). There was no difference in the number of visible lesions between the miR-451a treatment and controls. Treatment led to altered expression of several genes including YWHAZ, CAB39, MAPK1, β-catenin, and IL-6. Systemic treatment with a miR-451a inhibitor is a promising therapy for endometriosis that simultaneously affects multiple pathways driving the disease.

Genetics and Epigenetics of Infertility and Treatments on Outcomes

CONTEXT

Infertility affects 10% of the reproductive-age population. Even the most successful treatments such as assisted reproductive technologies still result in failed implantation. In addition, adverse pregnancy outcomes associated with infertility have been attributed to these fertility treatments owing to the presumed epigenetic modifications of in vitro fertilization and in vitro embryo development. However, the diagnosis of infertility has been associated with adverse outcomes, and the etiologies leading to infertility have been associated with adverse pregnancy and long-term outcomes.

EVIDENCE ACQUISITION

We have comprehensively summarized the data available through observational, experimental, cohort, and randomized studies to better define the effect of the underlying infertility diagnosis vs the epigenetics of infertility treatments on treatment success and overall outcomes.

EVIDENCE SYNTHESIS

Most female infertility results from polycystic ovary syndrome, endometriosis, and unexplained infertility, with some cases resulting from a polycystic ovary syndrome phenotype or underlying endometriosis. In addition to failed implantation, defective implantation can lead to problems with placentation that leads to adverse pregnancy outcomes, affecting both mother and fetus.

CONCLUSION

Current research, although limited, has suggested that genetics and epigenetics of infertility diagnosis affects disease and overall outcomes. In addition, other fertility treatments, which also lead to adverse outcomes, are aiding in the identification of factors, including the supraphysiologic hormonal environment, that might affect the overall success and healthy outcomes for mother and child. Further studies, including genome-wide association studies, epigenomics studies, and experimental studies, are needed to better identify the factors leading to these outcomes.

AC002454.1 and CDK6 synergistically promote endometrial cell migration and invasion in endometriosis

Previous lncRNA microarray screening found that the AC002454.1 gene was highly expressed in endometriosis (EMS), and these expression levels were highly correlated with cyclin-dependent kinase-6 (CDK6). This study investigated the expression level and correlation between AC002454.1 and CDK6 in endometrium tissues and the influence of these changes in expression upon the biological behavior of eutopic endometrial cells. We confirmed AC002454.1 and CDK6 mRNA and protein were highly expressed in ectopic and eutopic endometrial tissue from patients with EMS and were clearly correlated. In vitro, both AC002454.1 and CDK6 positively regulated the proliferation, migration and invasion ability of eutopic endometrial cells and could promote the transformation of cells from G0/G1 phase to S phase. AC002454.1 and CDK6 may have synergistic effects, thereby affecting the biological behavior of endometrial cells, and thus promote the progression of EMS.

Circulating miRNAs as Biomarkers for Endometriosis and Endometriosis-Related Ovarian Cancer-An Overview

Early detection and accurate diagnosis are pivotal in the management of endometriosis and endometriosis-related ovarian neoplasms (ERONs), yet there is no clear common ground regarding their pathogenesis. Endometriosis is a debilitating pathology that profoundly impairs the quality of life. Although the spontaneous resolution of endometriosis is possible, studies suggest that it can be a progressive condition, and ERONs can develop. The gold standard for diagnosis remains as the invasive method of laparoscopy followed by histological confirmation. In recent years, novel biomarkers have been discovered. MicroRNAs (miRNA) represent important epigenetic modulators of gene expression and are very attractive as biomarkers due to their lower complexity, tissue specificity, and stability in bodily fluids. Several studies have advanced the possibility of miRNAs becoming potential biomarkers in endometriosis and ERONs. Our aim is to bring these studies together in order to have a better understanding of whether, how, and when miRNAs might be used as biomarkers for these pathologies.

METHODS

We selected the reviewed papers from Google Academic, PubMed, and CrossRef. A total of eight studies met the inclusion criteria.

RESULTS

MiR-200 family, miR-143, 145, miR-20a, and miR199a were the most commonly dysregulated miRNAs in endometriosis, and miR-200 family was found to be dysregulated in both ERONs and endometriosis.

CONCLUSIONS

No single miRNA was considered as a sole biomarker for this pathology. However, since the prognostic value of biomarkers is generally enhanced if more are assessed at the same time, a panel of miRNAs could be a better indicator of the disease.

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.

Expression Profile Analysis of Circular RNAs in Ovarian Endometriosis by Microarray and Bioinformatics

Background

Endometriosis is a common gynecologic disorder with enigmatic etiopathogenesis and is characterized by tumor-like biological behaviors. Recently, circular RNAs (circRNAs) have attracted considerable attention because they exert very important functions in the progression of human cancers. However, little is known about the functions and molecular mechanism of circRNAs in endometriosis.

Material/Methods

A total of 20 patients with ovarian endometriosis and 4 normal endometrium from women free of endometriosis were included in this study. Ectopic endometrium tissues and paired eutopic endometrium tissues were collected from ovarian endometriosis patients. We assessed the expression profiles of circRNAs in endometriosis by microarray analysis. Expression of selected circRNAs in those tissues was detected by quantitative real-time PCR (qRT-PCR). Based on the target prediction, we constructed a circRNA-miRNA-mRNA competing endogenous RNA (ceRNA) network and elucidated circRNAs through Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses.

Results

We detected 2237 circRNAs, differentially expressed among 3 groups, and then found 8 circRNAs that may be involved in the epithelial-mesenchymal transition process. The qRT-PCR validation suggested that circ_103470 and circ_101102 matched the microarray results. The functional analysis revealed 17 pathways, such as the mTOR signaling pathway, the Hippo signaling pathway, and the HIF-1 signaling pathway, which may be associated with the pathogenesis and development of endometriosis.

Conclusions

In general, our results suggest that 2 downregulated circRNAs (circ_103470 and circ_101102) may regulated epithelial-mesenchymal transition in endometriosis via miR-141-5p, which may be a promising therapeutic target in the future.

The nervous system and genomics in endometriosis

Endometriosis is a gynaecological disease that occurs in approximately 10% to 15% of women of reproductive age and up to 47% of infertile women. The presence of implants of endometrial-like glands and stroma outside the uterus, characteristic of this disease, induce a wide variety of symptoms, mainly pelvic pain and infertility. Women suffering from this condition experience great distress, which significantly affects their quality of life. Numerous studies attempting to decipher the pathogenic mechanisms of endometriosis have been conducted around the world, yet its aetiology still remains unknown. It is widely believed that in women with endometriosis, the endometrium has characteristic features that allow the formation of implants once fragments have entered the peritoneal cavity through retrograde menstruation. Furthermore, a strong genetic tendency to develop the disease has been reported among patients and first-degree relatives. Thanks to the recent technological advances achieved in genomics and bioinformatics, a number of studies have had the potential to analyse several aspects of the pathogenesis of endometriosis from a genetic perspective. Due to the recent identification of nerve fibres in the endometrium of women with endometriosis, research on the neurogenesis of the disease has increased in the past few years. However, the genetic aspects of nerve growth in endometriosis have not been analysed in depth and further research providing important insights into the mechanisms that mediate pain in affected patients has the potential to contribute substantially to the future management of the condition.

Do MicroRNAs Modulate Visceral Pain?

Visceral pain, a common characteristic of multiple diseases relative to viscera, impacts millions of people worldwide. Although hundreds of studies have explored mechanisms underlying visceral pain, it is still poorly managed. Over the past decade, strong evidence emerged suggesting that microRNAs (miRNAs) play a significant role in visceral nociception through altering neurotransmitters, receptors and other genes at the posttranscriptional level. Under pathological conditions, one kind of miRNA may have several target mRNAs and several kinds of miRNAs may act on one target, suggesting complex interactions and mechanisms between miRNAs and target genes lead to pathological states. In this review we report on recent progress in examining miRNAs responsible for visceral sensitization and provide miRNA-based therapeutic targets for the management of visceral pain.

Endometrial miR-543 Is Downregulated During the Implantation Window in Women With Endometriosis-Related Infertility

BACKGROUND

Differentially expressed microRNAs (miRNAs) and their target mRNAs may lead to alterations in normal physiological status of the tissues and initiate pathological processes. The aim of this study was to investigate the expression of the most relevant miRNAs in the eutopic endometrial tissue during the window of implantation in women with endometriosis-related infertility.

METHODS

In the study, 76 infertile women with a regular menstrual cycle were recruited from the Center for Reproductive Medicine, Peking University Third Hospital between January 2014 and June 2016. We performed a combined messenger RNA and miRNA microarray and bioinformatics analysis of eutopic endometrium in 6 women with and without endometriosis-related infertility at the time of implantation window. Quantitative real-time polymerase chain reaction arrays were utilized to examine the expression levels of selected miRNAs (from 35 patients with endometriosis and 35 disease-free individuals at different menstrual stages).

RESULTS

Five differentially expressed miRNAs (miR-142-5p, miR-146a-5p, miR-1281, miR-940, and miR-4634) were significantly upregulated, whereas miR-543 was significantly downregulated in the eutopic endometrium during the window of implantation in patients with endometriosis. Further analysis showed that miR-543 was significantly upregulated at the peri-implantation phase compared with that at proliferative phase in the endometrium of disease-free patients (P < .05). However, the expression level of miR-543 was significantly decreased in patients with endometriosis (P < .05), especially downregulated at the window of implantation phase (P < .05).

CONCLUSIONS

miR-543 plays an important role during embryo implantation process and is associated with endometrial receptivity. Downregulation of miR-543 may affect embryo implantation, resulting in the pathogenesis of endometriosis-related infertility.

Inside the Endometrial Cell Signaling Subway: Mind the Gap(s)

Endometrial cells perceive and respond to their microenvironment forming the basis of endometrial homeostasis. Errors in endometrial cell signaling are responsible for a wide spectrum of endometrial pathologies ranging from infertility to cancer. Intensive research over the years has been decoding the sophisticated molecular means by which endometrial cells communicate to each other and with the embryo. The objective of this review is to provide the scientific community with the first overview of key endometrial cell signaling pathways operating throughout the menstrual cycle. On this basis, a comprehensive and critical assessment of the literature was performed to provide the tools for the authorship of this narrative review summarizing the pivotal components and signaling cascades operating during seven endometrial cell fate “routes”: proliferation, decidualization, implantation, migration, breakdown, regeneration, and angiogenesis. Albeit schematically presented as separate transit routes in a subway network and narrated in a distinct fashion, the majority of the time these routes overlap or occur simultaneously within endometrial cells. This review facilitates identification of novel trajectories of research in endometrial cellular communication and signaling. The meticulous study of endometrial signaling pathways potentiates both the discovery of novel therapeutic targets to tackle disease and vanguard fertility approaches.

Progesterone Resistance in Endometriosis: an Acquired Property?

Endometriosis is the growth of endometrial tissue outside the uterus and is characterized by progesterone resistance and changes in global and progesterone target gene expression. However, the mechanism behind this and whether it is innate, acquired, or present in both the eutopic and ectopic tissue in not always clear. We find large-scale gene expression studies in eutopic tissue, indicative of progesterone resistance, are often contradictory, potentially due to the dynamic nature of this tissue, whereas suppressed progesterone receptor expression is supported in ectopic but not eutopic tissue. This suggests more studies are required in eutopic tissue particularly, and that potentially the suppressed progesterone receptor (PR) expression is a consequence of the pathogenic process and exposure to the peritoneal environment.

Non-Coding RNAs in Endometrial Physiopathology

The Human Genome Project led to the discovery that about 80% of our DNA is transcribed in RNA molecules. Only 2% of the human genome is translated into proteins, the rest mostly produces molecules called non-coding RNAs, which are a heterogeneous class of RNAs involved in different steps of gene regulation. They have been classified, according to their length, into small non-coding RNAs and long non-coding RNAs, or to their function, into housekeeping non-coding RNAs and regulatory non-coding RNAs. Their involvement has been widely demonstrated in all cellular processes, as well as their dysregulation in human pathologies. In this review, we discuss the function of non-coding RNAs in endometrial physiology, analysing their involvement in embryo implantation. Moreover, we explore their role in endometrial pathologies such as endometrial cancer, endometriosis and chronic endometritis.

Endometriosis

Endometriosis is a common inflammatory disease characterized by the presence of tissue outside the uterus that resembles endometrium, mainly on pelvic organs and tissues. It affects ~5-10% of women in their reproductive years - translating to 176 million women worldwide - and is associated with pelvic pain and infertility. Diagnosis is reliably established only through surgical visualization with histological verification, although ovarian endometrioma and deep nodular forms of disease can be detected through ultrasonography and MRI. Retrograde menstruation is regarded as an important origin of the endometrial deposits, but other factors are involved, including a favourable endocrine and metabolic environment, epithelial-mesenchymal transition and altered immunity and inflammatory responses in genetically susceptible women. Current treatments are dictated by the primary indication (infertility or pelvic pain) and are limited to surgery and hormonal treatments and analgesics with many adverse effects that rarely provide long-term relief. Endometriosis substantially affects the quality of life of women and their families and imposes costs on society similar to those of other chronic conditions such as type 2 diabetes mellitus, Crohn's disease and rheumatoid arthritis. Future research must focus on understanding the pathogenesis, identifying disease subtypes, developing non-invasive diagnostic methods and targeting non-hormonal treatments that are acceptable to women who wish to conceive.

miR-194-3p Represses the Progesterone Receptor and Decidualization in Eutopic Endometrium From Women With Endometriosis

Progesterone resistance in the eutopic endometrium (EuE) is suggested to be a critical factor for decreased endometrial receptivity and implantation failure in reproductive-aged women with endometriosis. Altered expression of miRNAs has been reported to play an important role in the pathophysiology of endometriosis-associated infertility. However, the underlying mechanisms of aberrant progesterone receptor (PR) and deficient decidualization regulated by miRNAs in endometriosis have not been thoroughly elucidated. The goal of this study was to explore the regulation and roles of miR-194-3p in aberrant PR expression and impaired decidualization in endometrial stromal cells (ESCs) from the EuE of women with mild or minimal endometriosis. Using a series of studies, we observed decreased PR mRNA expression and an increasing PR-A/PR-B mRNA ratio trend in the midsecretory phase of the EuE of women with minimal or mild endometriosis (n = 19) compared with controls (n = 14); the increased expression of miR-194-3p in the endometriosis group was consistent with previous microarray analysis. We also found that PR protein levels were inhibited by the transfection of ESCs with an miR-194-3p mimic and upregulated by miR-194-3p inhibition. As predicted by the bioinformatic analysis, the 3'-untranslated region luciferase assay indicated the direct regulation of PR expression by miR-194-3p. Furthermore, miR-194-3p overexpression inhibited the in vitro decidualization of ESCs via both cellular morphological changes and prolactin levels. Therefore, our study demonstrated that miR-194-3p contributes to progesterone resistance in endometriosis, which hinders fertility by repressing the levels of PR and decidualization in the EuE. Thus, miR-194-3p regulation is a future therapeutic strategy for endometriosis.

Molecular and Cellular Pathogenesis of Endometriosis

BACKGROUND

A substantial body of studies supports the view that molecular and cellular features of endometriotic lesions differ from those of eutopic endometrium. Apart from that, evidence exists that the eutopic endometrium from pa-tients with endometriosis differs from that of females without endometriosis.

OBJECTIVE

Aberrant expression profiles include a number of non-steroid signaling pathways that exert their putative influ-ence on the pathogenesis of endometriosis at least in part via crosstalk(s) with estrogen-mediated mechanisms. A rational to focus research on non-steroid signal pathways is that they might be remunerative targets for the development and selection of novel therapeutics to treat endometriosis possibly without affecting estrogen levels.

RESULTS AND CONCLUSION

In this article, we describe molecular and cellular features of endometriotic lesions and focus on the canonical WNT/β-signaling pathway, a key regulatory system in biology (including stem cell homeostasis) and often in pathophysiological conditions such as endometriosis. Recently emerged novel biological concepts in signal transduction and gene regulation like exosomes and microRNAs are discussed in their putative role in the pathogenesis of endometriosis.

hsa-miRNA-154-5p expression in plasma of endometriosis patients is a potential diagnostic marker for the disease

RESEARCH QUESTION

As microRNA (miRNA) are stable in circulation, this study tested whether they could serve as putative non-invasive biomarkers for endometriosis, and their expression differences between endometriosis patients and controls. It also addressed whether the combination of differently expressed miRNA together with clinical parameters in a statistical model could distinguish between endometriosis patients and controls.

DESIGN

This prospective cohort study explored the possibility of using changes in extracellular miRNA spectra in plasma of 51 patients with endometriosis compared with 41 controls combined with clinical data as non-invasive biomarkers for the disease. The project was divided into three different phases for biomarker screening, discovery and validation. The differences in expression levels of plasma miRNA obtained from women with and without endometriosis were analysed with quantitative PCR-based microarrays. The diagnostic performance of the selected individual and/or combined differentially expressed miRNA candidates and clinical parameters was assessed using in silico bioinformatics modelling and receiver operating characteristic curve analysis.

RESULTS

Data showed that a specific plasma miRNA signature is associated with endometriosis and that hsa-miR-154-5p, which alone or in combination with hsa-miR-196b-5p, hsa-miR-378a-3p, and hsa-miR-33a-5p and the clinical parameters of body mass index and age, are potentially applicable for non-invasive diagnosis of the disease. Changes in the levels of expression of certain circulating plasma miRNA also occurred within the phases of the menstrual cycle.

CONCLUSIONS

miRNA seem to be promising candidates for the non-invasive diagnosis of endometriosis. Further, other clinical parameters may help in distinguishing women suffering from endometriosis from healthy individuals.

Micro-RNA profile and proteins in peritoneal fluid from women with endometriosis: their relationship with sterility

OBJECTIVE

To define the microRNA (miRNA) profile and its relationship with cytokines content in peritoneal fluid (PF) from endometriosis patients.

DESIGN

Case-control study.

SETTING

University hospital, research institute.

PATIENT(S)

One hundred twenty-six women with endometriosis (EPF) and 45 control women (CPF).

MAIN OUTCOMES MEASURE(S)

MiRNA arrays were prepared from six EPF and six CPF. Quantitative reverse transcription-polymerase chain reaction validation of nine selected miRNAs (miR-29c-3p, -106b-3p, -130a-3p, -150-5p, -185-5p, -195-5p, -451a, -486-5p, and -1343-5p) was performed. Vascular endothelial growth factor-A (VEGF-A), thrombospondin-1 (TSP-1), urokinase plasminogen activator (uPA), plasminogen activator inhibitor-1 (PAI-1), matrix metalloproteinase-3 (MMP3), tissue inhibitor of metalloproteinases type 1 (TIMP-1), interleukin (IL)-6, IL-8, IL-17A, macrophage inflammatory protein 1β (MIP1beta), platelet-derived growth factor α-polypeptide A, and regulated on activation, normal T cell expressed and secreted (RANTES) were quantified by ELISA and MILLIPLEX.

RESULT(S)

MiRNA arrays showed 126 miRNAs differentially expressed (fold change ±1.2) (78 down-regulated, 48 up-regulated) in EPF. Validation showed higher levels of miR-106b-3p, -451a, -486-5p, IL-6, IL-8, uPA, and TIMP-1 in EPF. In menstrual phase, EPF presented up-regulation of miR-106b-3p, -130a-3p, -150-5p, -185-5p, -451a, -486-5p, VEGF-A, IL-8, MIF 1β, uPA, and PAI-1 compared with other phases; however, CPF did not. MiRNA-486-5p was up-regulated in sterile EPF compared with sterile controls, and VEGF-A, IL-8, and TIMP-1 were increased in sterile and fertile EPF compared with fertile CPF.

CONCLUSION(S)

MiRNAs seem to be involved in the peritoneal alterations in endometriosis, suggesting new mechanisms by which ectopic lesions could implant in endometriosis patients; and to serve as biomarkers for fertility outcome prediction.

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.

Integration analysis of microRNA and mRNA paired expression profiling identifies deregulated microRNA-transcription factor-gene regulatory networks in ovarian endometriosis

BACKGROUND

The etiology and pathophysiology of endometriosis remain unclear. Accumulating evidence suggests that aberrant microRNA (miRNA) and transcription factor (TF) expression may be involved in the pathogenesis and development of endometriosis. This study therefore aims to survey the key miRNAs, TFs and genes and further understand the mechanism of endometriosis.

METHODS

Paired expression profiling of miRNA and mRNA in ectopic endometria compared with eutopic endometria were determined by high-throughput sequencing techniques in eight patients with ovarian endometriosis. Binary interactions and circuits among the miRNAs, TFs, and corresponding genes were identified by the Pearson correlation coefficients. miRNA-TF-gene regulatory networks were constructed using bioinformatic methods. Eleven selected miRNAs and TFs were validated by quantitative reverse transcription-polymerase chain reaction in 22 patients.

RESULTS

Overall, 107 differentially expressed miRNAs and 6112 differentially expressed mRNAs were identified by comparing the sequencing of the ectopic endometrium group and the eutopic endometrium group. The miRNA-TF-gene regulatory network consists of 22 miRNAs, 12 TFs and 430 corresponding genes. Specifically, some key regulators from the miR-449 and miR-34b/c cluster, miR-200 family, miR-106a-363 cluster, miR-182/183, FOX family, GATA family, and E2F family as well as CEBPA, SOX9 and HNF4A were suggested to play vital regulatory roles in the pathogenesis of endometriosis.

CONCLUSION

Integration analysis of the miRNA and mRNA expression profiles presents a unique insight into the regulatory network of this enigmatic disorder and possibly provides clues regarding replacement therapy for endometriosis.

Variability of genome-wide DNA methylation and mRNA expression profiles in reproductive and endocrine disease related tissues

Genome-wide association studies in the fields of reproductive medicine and endocrinology are yielding robust genetic variants associated with disease. Integrated genomic, transcriptomic, and epigenomic molecular profiling studies are common methodologies used to understand the biologic pathways perturbed by these variants. However, molecular profiling resources do not include the tissue most relevant to many female reproductive traits, the endometrium, while the parameters influencing variability of results from its molecular profiling are unclear. We investigated the sources of DNA methylation and RNA expression profile variability in endometrium (n = 135), endometriotic disease tissue (endometriosis), and subcutaneous abdominal fat samples from 24 women, quantifying between-individual, within-tissue (cellular heterogeneity), and technical variation. DNA samples (n = 96) were analyzed using Illumina HumanMethlylation450 BeadChip arrays; RNA samples (n = 39) were analyzed using H12-expression arrays. Variance-component analyses showed that, for the top 10–50% variable DNA methylation/RNA expression sites, between-individual variation far exceeded within-tissue and technical variation. Menstrual-phase accounted for most variability in methylation/expression patterns in endometrium (P_m = 7.8 × 10⁻³, P_e = 8.4 × 10⁻⁵) but not in fat and endometriotic tissue; age was significantly associated with DNA methylation profile of endometrium (P_m = 9 × 10⁻⁵) and endometriotic disease tissue (P_m = 2.4 × 10⁻⁵); and smoking was significantly associated with DNA methylation in adipose tissue (P_m = 1.8 × 10⁻³). Hierarchical cluster analysis showed significantly different methylation signatures between endometrium and endometriotic tissue enriched for WNT signaling, angiogenesis, cadherin signaling, and gonadotropin-releasing-hormone-receptor pathways. Differential DNA methylation/expression analyses suggested detection of a limited number of sites with large fold changes (FC > 4), but power calculations accounting for different sources of variability showed that for robust detection >500 tissue samples are required. These results enable appropriate study design for large-scale expression and methylation tissue-based profiling relevant to many reproductive and endocrine traits.

[Medical treatment of endometriosis: Hormonal treatment of pain, impact on evolution and future perspectives]

CONTEXT

Endometriosis is a chronic painful disease, for which hormone therapy is usually offered as a first line option to women not willing to conceive.

OBJECTIVES

To analyse and synthesize the literature, from 2006 onwards, on pain control, and disease evolution in oemn using combined hormonal contraceptives, progestins and GnRH analogs. Data on other current and future treatment perspectives is included as well.

SOURCES

Medline (Pubmed), the Cochrane Library, and endometriosis treatment recommendations published by European Society of Human Reproduction and Embryology (ESHRE), National Institute for health and Care Excellence (NICE), American College of Obstetricians and Gynecologists (ACOG), Royal College of Obstetricians and Gynaecologists (RCOG) and Société des Obstétriciens et Gynécologues du Canada (SOGC).

STUDY SELECTION

Meta-analysis and clinical trials are included.

RESULTS

Study quality is heterogeneous in general. Hormone therapy inconstantly allows pain relief and prevention of endometrioma and rectovaginal wall nodules recurrence. Available molecules and routes of administration as well as risk benefit balance are evaluated. Data on future perspectives are limited to date and do not allow use in routine.

CONCLUSION

Hormonal treatment of endometriosis relies on combined hormonal contraceptives (using different routes of administration), progestins and particularly the levonorgestrel-releasing IUS, and GnRH analogs as a last option, in combination with an add-back therapy. Promising alternatives are currently under preclinical and clinical evaluation.

Abnormal Pathways in Endometriosis in Relation to Progesterone Resistance: A Review

Introduction

Endometriosis is an estrogen-dependent disorder, and recent studies suggest that progesterone resistance may contribute to the development and pathophysiology of the disorder. Based on this, identification of genetic and molecular perturbations in the endometrium of women with endometriosis is an important step towards understanding the pathogenesis of the disease, and the development of novel treatment and diagnostic strategies.

Methods

A systematic literature search in PubMed and Embase was performed, and 118 articles were identified for further screening. Two reviewers performed article screening independently using Covidence, and 16 studies fulfilled the inclusion criteria. The Newcastle-Ottawa Scale was used to assess the quality of these studies.

Results

This review presents data from eutopic endometrial biopsies from women with and without endometriosis. Several biomarkers related to a downregulated progesterone response were identified and discussed in detail.

Conclusions

Our review demonstrates significant results concerning the biomarkers investigated, which may substantiate the theory of progesterone resistance in women with endometriosis. However, further research is necessary to determine their specific role and relevance.

Redox regulation of microRNAs in endometriosis-associated pain

Endometriosis is a chronic, painful condition with unknown etiology. A differential expression of microRNAs in the endometriotic tissues from women with endometriosis with pain compared to those without suggested a plausible role for miRNA or epigenetic mechanisms in the etiology of endometriotic pain. The peritoneal milieu is involved in maintenance of endometriotic lesion and nociception. We recently showed the mechanistic role for oxidized-lipoproteins (ox-LDLs) present in peritoneal fluid (PF) in endometriosis and pain. We explored the possibility of ox-LDLs modulating the expression of miRNAs in a manner similar to PF from women with endometriosis. Expression levels of miRNAs and their predicted nociceptive and inflammatory targets were determined in PF and ox-LDL treated human endometrial cell-lines. Samples from IRB-approved and consented patients with and without endometriosis or pain were used. These were compared to endometrial cell-lines treated with various forms of oxidized-lipoproteins. RNA (including miRNAs) were isolated from treated endometrial cells and expression levels were determined using commercial miRNome arrays. Cell lysates were used in immunoblotting for inflammatory proteins using a protein array. Twenty miRNAs including isoforms of miR-29, miR-181 and let-7 were mutually differentially expressed in cells treated with PF from endometriosis patients with pain and those treated with ox-LDL components. The ox-LDLs and endo-PF treatment also produced significant overexpression of microRNA predicted target genes nerve growth factor, interleukin-6 and prostaglandin E synthase and overexpression of their downstream protein targets Mip1α and MCP1. This study showed similarities between miRNA regulation in PF from endometriotic women and ox-LDLs present in abundance in the PF of these women. Key miRNAs responsible for targeting nociceptive and inflammatory molecules were downregulated in the presence of ox-LDLs and endo-PF, thus playing a role in the etiology of endometriotic pain. These redox-sensitive miRNAs can be of potential use as targets in the treatment of endometriosis-associated pain.

KRAS Activation and over-expression of SIRT1/BCL6 Contributes to the Pathogenesis of Endometriosis and Progesterone Resistance

Endometriosis is an inflammatory condition that is associated with progesterone resistance and cell proliferation, resulting in pain, infertility and pregnancy loss. We previously demonstrated phosphorylation of STAT3 in eutopic endometrium of infertile women with this disorder leading to over-expression of the oncogene BCL6 and stabilization of hypoxia-induced factor 1 alpha (HIF-1α). Here we report coordinated activation of KRAS and over-expression of Sirtuin 1 (SIRT1), a histone deacetylase and gene silencer, in the eutopic endometrium from women with endometriosis throughout the menstrual cycle. The mice with conditional activation of KRAS in the PGR positive cells reveal an increase of SIRT1 expression in the endometrium compared to control mice. The expression of progesterone receptor target genes including the Indian Hedgehog pathway genes are significantly down-regulated in the mutant mice. SIRT1 co-localizes with BCL6 in the nuclei of affected individuals and both proteins bind to and suppress the promoter of GLI1, a critical mediator of progesterone action in the Indian Hedgehog pathway, by ChIP analysis. In eutopic endometrium, GLI1 expression is reduced in women with endometriosis. Together, these data suggest that KRAS, SIRT1 and BCL6 are coordinately over-expressed in eutopic endometrium of women with endometriosis and likely participate in the pathogenesis of endometriosis.

mir-126 rs4636297 and TGFβRI rs334348 functional gene variants are associated with susceptibility to endometriosis and its severity

microRNAs (miRNAs) are negative regulators in a variety of cellular processes that occur in endometriosis. Therefore, functional polymorphisms in miRNA and miRNA binding sites may affect gene expression and contribute to susceptibility of endometriosis. In this study, we evaluated the association of two miRNA related polymorphisms, mir-126 rs4636297 and TGFβRI rs334348, with endometriosis risk and its severity. This case-control study was done on 157 endometriosis patients and 252 healthy women as a control group. Tetra amplification refractory mutation system-polymerase chain reaction (tetra-ARMS PCR) was designed to determine the polymorphisms. Our finding showed significant differences in genotype frequency of mir-126 rs4636297 between the groups (χ² = 6.26, p = 0.044). A significant protection against endometriosis was found for mir-126 rs4636297 in allele (G versus A allele: OR = 0.695, 95% CI = 0.519-0.931, p = 0.015) and genotype (GG versus AA genotype: OR = 0.451, 95%CI = 0.233-0.873, p = 0.018). Significant association was also observed between the A allele and severity of endometriosis (OR = 0.478, 95%CI = 0.297-0.768, p = 0.002). Moreover, we found a significant association between AA genotype with the risk of endometriosis (OR = 0.493, 95%CI = 0.250-0.970, p = 0.041) and its severity (OR = 0.240, 95%CI = 0.065-0.883, p = 0.032) regarding TGFβRI rs334348 polymorphism. These finding suggest that, for the first time, mir-126 rs4636297 and TGFβRI rs334348 polymorphisms may influence individual's susceptibility to endometriosis and its severity.

Endometrial Stromal and Epithelial Cells Exhibit Unique Aberrant Molecular Defects in Patients With Endometriosis

CONTEXT

Endometriosis is a chronic inflammatory disease that causes pain and infertility in women of reproductive age.

OBJECTIVE

To investigate the pathologic pathways in endometrial stromal and epithelial cells that contribute to the manifestation of endometriosis.

DESIGN

In vitro cellular and molecular analyses of isolated eutopic endometrial stromal and epithelial cells.

METHODS

Eutopic stromal and epithelial cells from endometriotic and normal patients were isolated by fluorescence-activated cell sorting for paired sibling RNA sequencing and microRNA microarray. Aberrant pathways were identified using ingenuity pathway analysis networks and confirmed with in vitro modulation of the affected pathways in stromal and epithelial cell cultures.

RESULTS

Both stromal versus epithelial cell types and paired endometriotic versus normal samples exhibited distinct hierarchical clustering. Compared to normal samples, there were 151 and 215 differentially expressed genes in the endometriotic stromal and epithelial populations, respectively, and concomitantly 9 and 16 differentially expressed microRNAs. Overall, endometriotic stromal and epithelial cells revealed distinct defects. In endometriotic stromal cells, key decidualization genes Zinc finger E-box Binding protein 1 (ZEB1), Heart And Neural crest Derivatives expressed 2 (HAND2), WNT4, and Interleukin 15 (IL-15) were found to be downregulated and Periostin (POSTN) and Matrix Metallopeptidase 7 (MMP7) were upregulated. Specifically, ZEB1 was downregulated in stromal cells by aberrant elevation in miR-200b. In contrast, ZEB1 was found to be upregulated in endometriotic epithelial cells through associated upregulation of transforming growth factor β1 (TGFβ1), inducer of the TGFβ1-Bone Morphogenetic Protein 2 (BMP2)-MMP2-Prostaglandin-endoperoxide Synthase 2 (COX2)-ZEB1 pathway, which activates epithelial-mesenchymal transition.

CONCLUSION

Manifestation of endometriosis involves dysregulation of unique molecular pathways within the diseased endometrial stromal and epithelial cells in the endometrium. Targeting the cell type-specific defects may offer a novel approach to treating endometriosis.

MiR-9-5p Down-Regulates PiT2, but not PiT1 in Human Embryonic Kidney 293 Cells

PiT1 (SLC20A1) and PiT2 (SLC20A2) are members of the mammalian type-III inorganic phosphate transporters and recent studies linked SLC20A2 mutations with primary brain calcifications. MicroRNAs (miRNAs) are endogenous noncoding regulatory RNAs and MicroRNA-9 (miR-9) modulates neurogenesis but is also involved with different types of cancer. We evaluated possible interactions between miR-9 and the phosphate transporters (PiT1 and PiT2). SLC20A2, platelet-derived growth factor receptor beta (PDGFRB) and Fibrillin-2 (FBN2) showed binding sites with high affinity for mir-9, In silico. miR-9 mimic was transfected into HEK293 cells and expression was confirmed by RT-qPCR. Overexpression of miR-9 in these cells caused a significant reduction in PiT2 and FBN2. PDGFRB appeared to be decreased, but was not significantly down-regulated. PiT1 showed no significant difference relative to controls. The down-regulation of PiT2 protein by miR-9 was confirmed by western blotting. In conclusion, we showed that miR-9 can down-regulate PiT2, in HEK293 cells. [corrected].

Progesterone-induced miR-133a inhibits the proliferation of endometrial epithelial cells

AIM

This study aimed to understand the role of miR-133a in progesterone actions, explore the regulative mechanism of the progesterone receptor, and investigate the effects of miR-133a on the progesterone-inhibited proliferation of mouse endometrial epithelial cells.

METHODS

The expression of miR-133a induced by progesterone was detected by quantitative real-time PCR both in vivo and in vitro. Ishikawa subcell lines stably transfected with progesterone receptor subtypes were used to determine the receptor mechanism of progesterone inducing miR-133a. Specific miR-133a mimics or inhibitors were transfected into mouse uteri and primary cultured endometrial epithelial cells to overexpress or downregulate the miR-133a. The roles of miR-133a in the cell cycle and proliferation of endometrial epithelial cells were analysed by flow cytometry and Edu incorporation analysis. The protein levels of cyclinD2 in uterine tissue sections and primary cultured endometrial epithelial cells were determined by immunohistochemistry and Western blot analysis.

RESULTS

Progesterone could induce miR-133a expression in a PRB-dependent manner in endometrial epithelial cells. miR-133a inhibited endometrial epithelial cell proliferation by arresting cell cycle at the G₁ -S transition. Moreover, miR-133a acted as an inhibitor in downregulating cyclinD2 in endometrial epithelial cells.

CONCLUSION

We showed for the first time that progesterone-induced miR-133a inhibited the proliferation of endometrial epithelial cells by downregulating cyclinD2. Our research indicated an important mechanism for progesterone inhibiting the proliferation of endometrial epithelial cells by inducing special miRNAs to inhibit positive regulatory proteins in the cell cycle.

Biomarkers in endometriosis: challenges and opportunities

Endometriosis is a debilitating gynecologic disease affecting millions of women across the world, with symptoms including dysmenorrhea, chronic pelvic pain, and infertility. Theorized to stem from the phenomenon of retrograde menstruation, the diagnosis of endometriosis is typically delayed by 8-10 years owing to misinterpretation of symptoms as common menstrual cramps in adolescent girls and young women. With increased incidence of endometriosis in young girls correlated with earlier menarche, the development of diagnostic biomarkers is imperative for diagnosing and treating women afflicted with endometriosis as early as we can. In the past few years, multiple reviews highlighted the list of potential diagnostic candidates in peritoneal fluid, blood, urine, and endometrial biopsies from endometriosis patients in different stages of disease and menstrual cycle. In this review, we explore the opportunities and challenges facing the field of diagnostic biomarkers for endometriosis. We highlight the importance of eutopic endometrium as a source of potential diagnostic biomarkers by looking at the expression levels of noncoding RNA in tissue as well as in blood. Finally, we discuss some of the challenges that hinder our efforts in validating candidate diagnostic biomarkers for endometriosis.

Progesterone Resistance in Endometriosis Is Modulated by the Altered Expression of MicroRNA-29c and FKBP4

CONTEXT

Endometriosis results in aberrant gene expression in the eutopic endometrium (EuE) and subsequent progesterone resistance. MicroRNA (miR) microarray data in a baboon model of endometriosis showed an increased expression of miR-29c.

OBJECTIVES

To explore the role of miR-29c in progesterone resistance in a subset of women with endometriosis.

DESIGN

MiR-29c expression was analyzed in the endometrium of baboons and women with or without endometriosis. The role in progesterone resistance and decidualization was analyzed by transfecting human uterine fibroblast cells with miR-29c.

PATIENTS

Subjects diagnosed with deep infiltrative endometriosis (DIE) by transvaginal ultrasound with bowel preparation underwent surgical excision of endometriosis. Eutopic secretory endometrium was collected pre- and postoperatively. Women with normal EuE and without DIE served as controls.

RESULTS

Quantitative reverse transcription polymerase chain reaction demonstrated that miR-29c expression increased, while the transcript levels of its target, FK506-binding protein 4 (FKBP4), decreased in the EuE of baboons following the induction of endometriosis. FKBP4 messenger RNA and decidual markers were statistically significantly decreased in decidualized human uterine fibroblast cells transfected with a miR-29c mimic compared with controls. Human data corroborated our baboon data and demonstrated higher expression of miR-29c in endometriosis EuE compared with normal EuE. MiR-29c was significantly decreased in endometriosis EuE postoperatively compared with preoperative tissues, and FKBP4 showed an inverse trend following radical laparoscopic resection surgery.

CONCLUSIONS

We demonstrate that miR-29c expression is increased in EuE of baboons and women with endometriosis, which might contribute to a compromised progesterone response by diminishing the levels of FKBP4. Resection of DIE is likely to reverse the progesterone resistance associated with endometriosis in women.