MicroRNA signature and regulatory functions in the endometrium during normal and disease states

Diagnostic Value and Molecular Function of MicroRNAs in Endometrial Diseases: A Systematic Review

The human endometrium experiences significant cyclic morphological and biochemical changes throughout the menstrual cycle to prepare for embryo implantation. These processes are meticulously regulated by ovarian steroids and various locally expressed genes, encompassing inflammatory reactions, apoptosis, cell proliferation, angiogenesis, differentiation (tissue formation), and tissue remodeling. MicroRNAs (miRNAs) have been recognized as crucial regulators of gene expression, with their altered expression being linked to the onset and progression of various disorders, including cancer. This review examines the expression of miRNAs in the endometrium and their potential regulatory roles under pathological conditions such as endometriosis, recurrent implantation failure and endometrial cancer. Given miRNAs' critical role in maintaining gene expression stability, understanding the regulatory mechanisms of endometrial miRNAs and identifying their specific target genes could pave the way for developing preventive and therapeutic strategies targeting specific genes associated with these reproductive disorders.

Uterine fluid microRNAs in repeated implantation failure

Recurrent implantation failure (RIF) is a significant obstacle in assisted reproductive procedures, primarily because of compromised receptivity. As such, there is a need for a dependable and accurate clinical test to evaluate endometrial receptiveness, particularly during embryo transfer. MicroRNAs (miRNAs) have diverse functions in the processes of implantation and pregnancy. Dysregulation of miRNAs results in reproductive diseases such as recurrent implantation failure (RIF). The endometrium secretes several microRNAs (miRNAs) during the implantation period, which could potentially indicate whether the endometrium is suitable for in vitro fertilization (IVF). The goal of this review is to examine endometrial miRNAs as noninvasive biomarkers that successfully predict endometrium receptivity in RIF.

MiRNAs related in signaling pathways of women's reproductive diseases: an overview

BACKGROUND

One of the main health issues that can affect women's health is reproductive diseases, such as polycystic ovary syndrome (PCOS), endometriosis (EMs), uterine leiomyomas (ULs), and ovarian cancer (OC). Although these diseases are very common, we do not have a complete understanding of their underlying cellular and molecular mechanisms. It is important to mention that the majority of patients are diagnosed with these diseases at later stages because of the absence of early diagnostic techniques and dependable molecular indicators. Hence, it is crucial to discover novel and non-invasive biomarkers that have prognostic, diagnostic and therapeutic capabilities. MiRNAs, also known as microRNAs, are small non-coding RNAs that play a crucial role in regulating gene expression at the post-transcriptional level. They are short in length, typically consisting of around 22 nucleotides, and are highly conserved across species. Numerous studies have shown that miRNAs are expressed differently in various diseases and can act as either oncogenes or tumor suppressors.

METHODS

The author conducted a comprehensive review of all the pertinent papers available in web of science, PubMed, Google Scholar, and Scopus databases.

RESULTS

We achieved three goals: providing readers with better information, enhancing search results, and making peer review easier.

CONCLUSIONS

This review focuses on the investigation of miRNAs and their involvement in various reproductive disorders in women, including their molecular targets. Additionally, it explores the role of miRNAs in the development and progression of these disorders.

From Genes to Therapy: Pituitary Adenomas in the Era of Precision Medicine

This review presents a comprehensive analysis of pituitary adenomas, a type of brain tumor with diverse behaviors and complexities. We cover various treatment approaches, including surgery, radiotherapy, chemotherapy, and their integration with newer treatments. Key to the discussion is the role of biomarkers in oncology for risk assessment, diagnosis, prognosis, and the monitoring of pituitary adenomas. We highlight advances in genomic, epigenomic, and transcriptomic analyses and their contributions to understanding the pathogenesis and molecular pathology of these tumors. Special attention is given to the molecular mechanisms, including the impact of epigenetic factors like histone modifications, DNA methylation, and transcriptomic changes on different subtypes of pituitary adenomas. The importance of the tumor immune microenvironment in tumor behavior and treatment response is thoroughly analyzed. We highlight potential breakthroughs and innovations for a more effective management and treatment of pituitary adenomas, while shedding light on the ongoing need for research and development in this field to translate scientific knowledge into clinical advancements, aiming to improve patient outcomes.

MicroRNAs in equine Endometritis: A review of pathophysiology and molecular insights for diagnostic and therapeutic strategies

Endometritis plays an important role in mare infertility. Certain infectious agents interfere with the innate immune system of endometrium, causing a systemic inflammatory response that lasts for a long time and circulates via the blood or cellular degeneration, leading to endometritis due to bacterial endotoxins. Different small, non-coding RNA molecules are involved in many biological functions. For instance, microRNAs (miRNAs) are involved in the post-transcriptional regulation of gene expression. These miRNAs are important regulators of gene expression, primarily via inhibiting transcription and translation processes. This manuscript reviews: (1) pathomorphological findings in equine endometritis, (2) the expression and effects of eca-miR-17, eca-miR-223, eca-miR-200a, eca-miR-155, and eca-miR-205 in endometritis and (3) the therapeutic role of miRNA in equine endometritis. The miRNAs have a vital regulatory role in a wide range of inflammatory diseases by regulating the molecular mechanism of cytokines that cause inflammation through signal pathways. This review emphasizes the demand for cutting-edge genetic technologies and the development of novel pharmaceutical preparations to improve our understanding of the genes encoding by these miRNAs. It also focuses on the efficacy of miRNAs for control, early diagnosis, and prevention of endometritis.

Circulating microRNAs as Potential Biomarkers for the Diagnosis of Endometrial Cancer: a Meta-Analysis

Endometrial cancer (EC) is the most common female genital tract malignancy worldwide. Many investigators have confirmed the possibility of using circulating miRNAs to diagnose EC; however, the results were inconsistent. Therefore, we performed the current meta-analysis to systematically evaluate the diagnostic value of circulating miRNAs in EC. We carefully searched relevant articles published prior to February 15, 2022 in the databases of PubMed, Embase, Web of Science, Cochrane Library, Wanfang database, and China National Knowledge Infrastructure (CNKI) based on PRISMA statement. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC) were calculated to test the diagnostic accuracy. Furthermore, subgroup analyses were performed to identify the potential sources of heterogeneity, and the Deeks' funnel plot asymmetry test was used to evaluate the potential publication bias. Twenty-one studies from 12 articles including a total of 2305 participants (1341 EC patients and 964 controls) were included in the current diagnostic meta-analysis. The overall pooled results of miRNA for EC diagnosis were: sensitivity, 0.84 (95% CI: 0.79-0.88); specificity, 0.87 (95% CI: 0.79-0.91); PLR, 6.3 (95% CI: 3.9-10.0); NLR, 0.18 (95% CI: 0.13-0.25); DOR, 35 (95% CI: 17-71); and AUC was 0.91 (95% CI: 0.89-0.94). Subgroup analysis suggested that miRNA cluster, serum type, and large sample sizes showed a better diagnostic accuracy. Moreover, there was no significant publication bias. Circulating miRNAs have great potential as novel non-invasive biomarkers for EC diagnosis.

Effects of selective inhibition of prostaglandin E2 receptors EP2 and EP4 on the miRNA profile in endometriosis

Endometriosis is an estrogen-dependent, progesterone-resistant, chronic inflammatory gynecological disease of reproductive-age women. Two major clinical symptoms of endometriosis are chronic pelvic pain and infertility, which profoundly affect the quality of life in women. Current hormonal therapies to induce a hypoestrogenic state are unsuccessful because of undesirable side effects, reproductive health concerns, and failure to prevent disease recurrence. Prostaglandin E₂ (PGE₂) plays an important role in the survival and growth of endometriotic lesions. MicroRNAs (miRNAs) are small, noncoding RNAs that control gene expressions through multiple mechanisms and have important roles in the pathogenesis of endometriosis. The objective of the present study is to determine the effects of pharmacological inhibition of PGE₂ receptors, EP2 and EP4, on miRNA profile in endometriosis. The novel results collectively indicate that inhibition of PGE₂-EP2/EP4 signaling regulated several miRNA clusters associated with cell adhesion, migration, invasion, survival and growth in cell-specific and the chromosome-specific manner and reverses the epigenetic silencing of proapoptotic miRNAs 15a and 34c in the human endometriotic epithelial and stromal cells and experimental endometriotic lesions. Thus, selective inhibition of EP2/EP4 receptors could emerge as a potential nonsteroidal therapy for endometriosis.

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.

Spatiotemporal expression pattern of miR-205, miR-26a-5p, miR-17-5p, let-7b-5p, and their target genes during different stages of corpus luteum in Egyptian buffaloes

Background

No doubt that the corpus luteum (CL) plays a vital role in the regulation of female cyclicity in mammals. The scenarios among microRNAs (miRNAs) and their target genes and steroid hormones {estradiol (E2) and progesterone (P4)} are required for better understanding the molecular regulation of CL during its formation, maturation, and regression. We aimed to (I) study the changes in the relative abundance of miR-205, miR-26a-5p, miR-17-5p, and let-7b-5p and their target genes: LHCGR, CASP3, PCNA, AMH, and PLA2G3, during different stages of corpus luteum in Egyptian buffaloes, and (II) and to address different scenarios between steroid concentrations in the serum and the expression pattern of selected miRNAs and their targets.

Methods

The paired ovaries and blood samples were collected from apparently healthy 50 buffalo cows at a private abattoir. The ovaries bearing CL were macroscopically divided according to their morphological structure and color into hemorrhagic (CLH), developing (CLD), mature (CLM), regressed (CLR), and albicans (CLA). Small pieces from different stages of CL (CLH, CLD, CLM, CLR, and CLA) were cut and immediately kept at − 80 °C for total RNA isolation and qRT-PCR. The serum was separated for steroid level estimation.

Results

The LHCGR was expressed during different stages of CL, and the peak of expression was at the mid-luteal stage. The CASP3 revealed a stage-specific response at different stages of CL. The PCNA has an essential role in cellular proliferation in buffaloes CL. Both expression patterns of PLA2G3 and AMH were found over the various developmental and regression stages. It was noticed that miR-205 is conserved to target LHCGR and CASP3 transcripts. Moreover, CASP3 and AMH were targeted via miR-26a-5p. Additionally, the CASP3 and PLA2G3 were targeted via let-7b-5p. The P4 level reached its peak during CLM. There were positive and negative strong correlations between miRNAs (miR-26a-5p and miR-205), target genes (LHCGR and CASP3) during different stages of CL, and steroid hormones in the serum.

Conclusions

Taken together, the orchestrated pattern among miRNAs, target genes, and steroid hormones is essential for maintaining the proper development and function of CL in buffalo cows.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43141-022-00320-9.

Comparative study of endometrial & subendometrial angiogenesis in unexplained infertile versus normal fertile women

Background & objectives:

Local angiogenesis in endometrium has been shown to be an essential pre-requisite for endometrial receptivity needed for implantation and gestation. Recently, numerous diagnostic gears have been projected to ‘measure’ or ‘estimate’ the endometrial receptivity relying upon angiogenic factors helping throughout implantation. This study evaluated the endometrial and subendometrial blood flow and the local endometrial gland vascular endothelial growth factor (EG-VEGF) expression as markers of local angiogenesis.

Methods:

The present study was done to give quantitative assessment of endometrial thickness (ET), endometrial blood flow and subendometrial blood flow colour Doppler indices with endometrial vascular zones. Endometrial biopsy was taken and with VEGF stained and scored with immunohistochemistry.

Results:

The mean ET for fertile women was 9.41 mm, while in unexplained infertile women it was around 7.90 mm. Upon comparison of ET with EG-VEGF which is considered as a gold standard with correlation coefficient, the present study suggested a positive correlation of EG-VEGF with ET, endometrial pulsatility index (PI), and subendometrial PI also the vascular zones were considered as significant. However, a strong negative correlation was seen with subendometrial resistivity index and PI.

Interpretation & conclusions:

The present study suggests that uterine ultrasound, uterine colour Doppler and EG-VEGF are parameters which can be used as markers of local angiogenesis for endometrial receptivity in the evaluation of women with unexplained infertility.

MicroRNA: A Potential Diagnosis for Male Infertility

Male infertility is one of the major global health problems, in particular, in more than half of the affected men. Genetic factors are important for identifying men with idiopathic infertility along with semen analysis. Valid and useful information can be obtained through non-invasive molecular research. Among these, small single-stranded non-coding RNA molecules of microRNAs (abbreviated miRNAs) are non-invasive biomarkers with a diagnostic value by regulating the post-transcriptional gene silence through repression and prevention of the translation process. The association between various types of male infertility and miRNA regulation changes has been evaluated to understand the biological function of miRNA and gene targets. Accordingly, further study of the function of miRNAs associated with reproductive disorders could lead researchers to further understand the molecular mechanisms of male infertility in order to find effective biomarkers and therapeutic strategies. Therefore, the present review article aimed at scrutinizing those researches investigating the altered miRNA expression in testicles, epididymis, and spermatozoa.

Alterations in the Expression Profile of Serum miR-155, miR-223, miR-17, miR-200a, miR-205, as well as Levels of Interleukin 6, and Prostaglandins during Endometritis in Arabian Mares

So far the intimate link between serum microRNA (miRNA) and uterine inflammation in mares is unknown. We aimed (I) to investigate expression profile of eca-miR-155, eca-miR-223, eca-miR-17, eca-miR-200a, and eca-miR-205 (II) and to measure concentrations of interleukin 6 (IL-6), and prostaglandins (PGF_2α and PGE₂) in serum of mares with healthy and abnormal uterine status (endometritis). This study was conducted on 80 Arabian mares: young (4–7 years), and old (8–14 years). Mares were divided into 48 sub-fertile (endometritis) and 32 fertile (control) at stud farms. Serum was collected for measuring IL-6, PGF_2α, and PGE₂, as well as miRNA isolation and qRT-PCR. Concentrations of IL-6, PGE₂, and PGF_2α were higher in mares with endometritis compared to control. Age of mares had a remarkable effect on IL-6, PGE₂, and PGF_2α concentrations. Relative abundance of eca-miR-155, eca-miR-223, eca-miR-17, eca-miR-200a, and eca-miR-205 was higher in both young and old mares with endometritis. We noticed that eca-miR-155, eca-miR-223, eca-miR-200a, and eca-miR-205 revealed higher expression level in old than young mares with endometritis. This is the first study that has revealed the changes in cell free miRNA and serum inflammatory mediators during endometritis, and these findings could be used for a better understanding the pathophysiology mechanisms of endometritis in equine.

Circulating miRNA 27a and miRNA150-5p; a noninvasive approach to endometrial carcinoma

The search for novel non-invasive biomarkers such as epigenetic molecular markers is new hope for common and burdensome cancers. We aim to assess serum expression of miRNA 27a and miRNA150-5p in endometrial cancer patients. Serum was drawn for 36 un-intervened endometrial cancer patients scheduled for hysterectomy and 35 controls. miRNA 27a and miRNA150-5p were measured by real time reverse transcription polymerase chain reaction. Significant overexpression of both miRNA in patients (p < 0.001). At cutoffs 0.2872 & > 1.02, miRNA 27a showed 100% sensitivity, specificity, positive and negative predictive values. miRNA150-5p showed 88.89% sensitivity, 100% specificity, 100% positive and 78.9% negative predictive values. Areas under curve were 1.0 for miRNA 27a, 0.982 for miRNA 150 performing much better than Ca125. miRNA 27a was significantly associated with type I endometroid endometrial cancer. Conclusion: miRNA 27a and miRNA-150-5P can be suggested as promising biomarkers of endometrial cancer possibly part of a miRNA panel for management.

MicroRNA-Mediated Gene Regulatory Mechanisms in Mammalian Female Reproductive Health

Mammalian reproductive health affects the entire reproductive cycle starting with the ovarian function through implantation and fetal growth. Various environmental and physiological factors contribute to disturbed reproductive health status leading to infertility problems in mammalian species. In the last couple of decades a significant number of studies have been conducted to investigate the transcriptome of reproductive tissues and organs in relation to the various reproductive health issues including endometritis, polycystic ovarian syndrome (PCOS), intrauterine growth restriction (IUGR), preeclampsia, and various age-associated reproductive disorders. Among others, the post-transcriptional regulation of genes by small noncoding miRNAs contributes to the observed transcriptome dysregulation associated with reproductive pathophysiological conditions. MicroRNAs as a class of non-coding RNAs are also known to be involved in various pathophysiological conditions either in cellular cytoplasm or they can be released to the extracellular fluid via membrane-bounded extracellular vesicles and proteins. The present review summarizes the cellular and extracellular miRNAs and their association with the etiology of major reproductive pathologies including PCOS, endometritis, IUGR and age-associated disorders in various mammalian species.

MicroRNAome: Potential and Veritable Immunomolecular Therapeutic and Diagnostic Baseline for Lingering Bovine Endometritis

The bovine endometrium is a natural pathogen invasion barrier of the uterine tissues' endometrial epithelial cells that can resist foreign pathogen invasion by controlling the inflammatory immune response. Some pathogens suppress the innate immune system of the endometrium, leading to prolonged systemic inflammatory response through the blood circulation or cellular degradation resulting in bovine endometritis by bacterial endotoxins. The microRNA (miRNA) typically involves gene expression in multicellular organisms in post-transcription regulation by affecting both the stability and the translation of messenger RNA. Accumulated evidence suggests that miRNAs are important regulators of genes in several cellular processes. They are a class of endogenous non-coding RNAs, which play pivotal roles in the inflammatory response of reproductive diseases. Studies confirmed that miRNAs play a key regulatory role in various inflammatory diseases by mediating the molecular mechanism of inflammatory cytokines via signal pathways. It implicates some miRNAs in the occurrence of bovine endometritis, resorting to regulating the activities of some inflammatory cytokines, chemokine, differentially expressed genes, and protein through modulating of specific cellular signal pathways functions. This review dwells on improving the knowledge of the role of miRNAs involvement in inflammatory response as to early diagnosis, control, and prevention of bovine endometritis and consequently enlighten on the molecular improvement of the genes coded by various differentially expressed miRNA through the need to adopt recent genetic technologies and the development of new pharmaceutical preparations.

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-30a-3p regulates epithelial-mesenchymal transition to affect embryo implantation by targeting Snai2†

OBJECTIVE

To study the potential role of miR-30a-3p in embryo implantation and explore underlying mechanisms.

METHODS

We first established normal pregnancy, pseudopregnancy, delayed implantation, and artificial decidualization mouse models. Next, we detected miR-30a-3p expression profiles of these models with real-time reverse transcription PCR(qRT-PCR), then predicted potential target genes through a dual-luciferase assay. Immunofluorescence-fluorescence in situ hybridization co-located miR-30a-3p and target genes. We then examined the effect of miR-30a-3p on embryo implantation in vivo and in vitro. Wound healing and transwell assays were employed to explore possible miR-30a-3p effects on epithelial-mesenchymal transition (EMT), before molecules related to the latter process were examined with qRT-PCR.

RESULTS

MiR-30a-3p expression decreased significantly on embryo implantation day, compared with the peri-implantation period (P < 0.05). Identified target gene Snai2 expression increased significantly during implantation (P < 0.05). In vivo and in vitro analysis showed that up-regulation of miR-30a-3p by agomir and mimics resulted in decreased implantation sites and embryo implantation rate. Transfection of miR-30a-3p mimics to HEC-1-b cells decreased expression of Snai2 and mesenchymal markers (Vimentin and N-cadherin). Furthermore, wound healing area decreased, as did migration and invasion capacity.

CONCLUSION

MiR-30a-3p is down-regulated in the embryo implantation period and might have some effect on embryo implantation by acting as a suppressor of EMT through targeting Snai2.

Endometriosis and nuclear receptors

BACKGROUND

Endometriosis is recognized as a steroid-dependent disorder; however, the precise roles of nuclear receptors (NRs) in steroid responsiveness and other signaling pathways are not well understood.

OBJECTIVE AND RATIONALE

Over the past several years, a number of paradigm-shifting breakthroughs have occurred in the area of NRs in endometriosis. We review and clarify new information regarding the mechanisms responsible for: (i) excessive estrogen biosynthesis, (ii) estrogen-dependent inflammation, (iii) defective differentiation due to progesterone resistance and (iv) enhanced survival due to deficient retinoid production and action in endometriosis. We emphasize the roles of the relevant NRs critical for these pathological processes in endometriosis.

SEARCH METHODS

We conducted a comprehensive search using PubMed for human, animal and cellular studies published until 2018 in the following areas: endometriosis; the steroid and orphan NRs, estrogen receptors alpha (ESR1) and beta (ESR2), progesterone receptor (PGR), steroidogenic factor-1 (NR5A1) and chicken ovalbumin upstream promoter-transcription factor II (NR2F2); and retinoids.

OUTCOMES

Four distinct abnormalities in the intracavitary endometrium and extra-uterine endometriotic tissue underlie endometriosis progression: dysregulated differentiation of endometrial mesenchymal cells, abnormal epigenetic marks, inflammation activated by excess estrogen and the development of progesterone resistance. Endometriotic stromal cells compose the bulk of the lesions and demonstrate widespread epigenetic abnormalities. Endometriotic stromal cells also display a wide range of abnormal NR expression. The orphan NRs NR5A1 and NR2F2 compete to regulate steroid-synthesizing genes in endometriotic stromal cells; NR5A1 dominance gives rise to excessive estrogen formation. Endometriotic stromal cells show an abnormally low ESR1:ESR2 ratio due to excessive levels of ESR2, which mediates an estrogen-driven inflammatory process and prostaglandin formation. These cells are also deficient in PGR, leading to progesterone resistance and defective retinoid synthesis. The pattern of NR expression, involving low ESR1 and PGR and high ESR2, is reminiscent of uterine leiomyoma stem cells. This led us to speculate that endometriotic stromal cells may display stem cell characteristics found in other uterine tissues. The biologic consequences of these abnormalities in endometriotic tissue include intense inflammation, defective differentiation and enhanced survival.

WIDER IMPLICATIONS

Steroid- and other NR-related abnormalities exert genome-wide biologic effects via interaction with defective epigenetic programming and enhance inflammation in endometriotic stromal cells. New synthetic ligands, targeting PGR, retinoic acid receptors and ESR2, may offer novel treatment options.

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.

Association between microRNA machinery gene polymorphisms and recurrent implantation failure

The present study aimed to investigate the potential association of five miRNA machinery gene polymorphisms (DICER1 rs3742330A>G, DROSHA rs10719T>C, RAN rs14035C>T, XPO5 rs11077A>C and DGCR8 rs417309G>A) with recurrent implantation failure (RIF), a clinical condition in which good-quality embryos repeatedly fail to implant following two or more in vitro fertilization cycles, and its associated risk factors in Korean women. Therefore, the present study performed genotype analysis and assessed the frequency of these miRNA gene polymorphisms in patients diagnosed with RIF (n=119) and randomly selected controls (n=210) with at least one live birth and no history of pregnancy loss. The DROSHA rs10719T>C and RAN rs14035C>T polymorphisms were identified to be significantly associated with decreased prevalence of RIF. Additionally, the DROSHA rs10719 TC and the RAN rs14035 CT genotypes were present at significantly lower frequencies in the RIF group than in the control group (adjusted odds ratio=0.550; 95% CI, 0.339-0.893; P=0.016; and adjusted odds ratio=0.590; 95% CI, 0.363-0.958; P=0.033, respectively). Furthermore, the combined RAN rs14035 CT+TT genotype was observed to be associated with decreased RIF prevalence (adjusted odds ratio=0.616; 95% CI, 0.386-0.982; P=0.042). Genotype combination analysis for the various miRNA polymorphisms revealed that the DROSHA TC genotype exhibited a highly significant negative association with RIF prevalence when combined with the RAN CT genotype (adjusted odds ratio=0.314; 95% CI, 0.147-0.673; P=0.003; false discovery rate-adjusted P=0.023). The present study revealed an association between the DROSHA rs10719 and RAN rs14035 3'UTR polymorphisms and decreased risk of RIF in Korean women, which suggests that these gene polymorphisms could represent potential markers for predicting RIF risk.

MicroRNA targeting of the non-canonical planar cell polarity pathway in the developing neural tube

MicroRNAs (miRNAs) provide context-dependent transcriptional regulation of genes comprising signalling networks throughout the developing organism including morphogenesis of the embryonic neural tube (NT). Using a high-sensitivity, high-coverage microarray analysis platform, miRNA expression in the murine embryonic NT during the critical stages of its formation was examined. Analysis of a number of differentially expressed (DE) miRNAs enabled identification of several gene targets associated with cellular processes essential for normal NT development. Using computational pathway analysis, interactive biologic networks and functional relationships connecting DE miRNAs with their targeted messenger RNAs (mRNAs) were identified. Potential mRNA targets and a key signal transduction pathway governing critical cellular processes indispensable for normal mammalian neurulation were also identified. RNA preparations were also used to hybridize both miRNA arrays and mRNA arrays allowing miRNA-mRNA target analysis using data of DE miRNAs and DE mRNAs - co-expressed in the same developing NT tissue samples. Identification of these miRNA targets provides key insight into the epigenetic regulation of NT development as well as into potential mechanistic underpinning of NT defects. SIGNIFICANCE OF THE STUDY: This study underscores the premise that microRNAs are potential coordinators of normal neural tube (NT) formation, via regulation of the crucial, planar cell polarity pathway. Any alteration in their expression during neurulation would result in abnormal NT development.

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.

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.

miRNAs as Candidate Biomarker for the Accurate Detection of Atypical Endometrial Hyperplasia/Endometrial Intraepithelial Neoplasia

Endometrial cancer is the most common gynecologic malignancy in developed countries. Estrogen-dependent tumors (type I, endometrioid) account for 80% of cases and non-estrogen-dependent (type II, non-endometrioid) account for the rest. Endometrial cancer type I is generally thought to develop via precursor lesions along with the increasing accumulation of molecular genetic alterations. Endometrial hyperplasia with atypia/Endometrial Intraepithelial Neoplasia is the least common type of hyperplasia but it is the type most likely to progress to type I cancer, whereas endometrial hyperplasia without atypia rarely progresses to carcinoma. MicroRNAs are a class of small, non-coding, single-stranded RNAs that negatively regulate gene expression mainly binding to 3′-untranslated region of target mRNAs. In the current study, we identified a microRNAs signature (miR-205, miR-146a, miR-1260b) able to discriminate between atypical and typical endometrial hyperplasia in two independent cohorts of patients. The identification of molecular markers that can distinguish between these two distinct pathological conditions is considered to be highly useful for the clinical management of patients because hyperplasia with an atypical change is associated with a higher risk of developing cancer. We show that the combination of miR-205, −146a, and −1260b has the best predictive power in discriminating these two conditions (>90%). With the aim to find a biological role for these three microRNAs, we focused our attention on a common putative target involved in endometrial carcinogenesis: the oncosuppressor gene SMAD4. We showed that miRs-146a,−205, and−1260b directly target SMAD4 and their enforced expression induced proliferation and migration of Endometrioid Cancer derived cell lines, Hec1a cells. These data suggest that microRNAs-mediated impairment of the TGF-β pathway, due to inhibition of its effector molecule SMAD4, is a relevant molecular alteration in endometrial carcinoma development. Our findings show a potential diagnostic role of this microRNAs signature for the accurate diagnosis of Endometrial hyperplasia with atypia/Endometrial Intraepithelial Neoplasia and improve the understanding of their pivotal role in SMAD4 regulation.

Expression profiling of selected miRNAs in equine endometrium in response to LPS challenge in vitro: A new understanding of the inflammatory immune response

Bacterial infections of the genital tract are the major cause of reproductive failure in the mares. MiRNAs are important regulators of gene expression, mostly through transcriptional and translational regression. We hypothesized that LPS induced aberrant expression of miRNAs and their targets, which are involved in regulation of uterine homeostasis. Three groups of primary endometrial epithelial and stromal cells, and endometrial tissue explants were cultured. The 1^st group was kept as control, while the 2^nd and 3^rd groups were challenged with low (0.5 μg/mL) or high (3.0 μg/mL) doses of Lipopolysaccharides (LPS). Cell pellets and tissue explants were collected after 24 and 48 h, for total RNA isolation and qRT-PCR of the selected miRNAs and their targets. Culture media and cell lysates were collected after 24 and 48 h, for cytokines (IL6 and TNF_α) and prostaglandins (PGE₂ & PGF_α2) measurement. Both endometrial cells expressed TLR4 and its accessory molecules (MyD88 & CD14) that are required for triggering inflammatory immune response after LPS, via up-regulation of TRAF6, TNF_α, IL6 and IL8, compared to the respective control. After both doses of LPS challenge, miR-155, miR-223 and miR-17 were significantly increased; miR-181b, miR-21 and let-7a were significantly decreased compared to respective controls. Interestingly, miR-24 and miR-532-5p were clearly up-regulated after only the low LPS dose. TNF_α, IL6 and PGs in culture media and from cell lysates revealed dose- and time-dependent patterns, after LPS. Results indicated that both epithelial and stromal cells have a primary role in innate immune response after LPS challenge, while this recognition occurred via TLR4 and its accessory molecules. Dysregulation of miRNAs and their targets expression after LPS might affect normal uterine function through perturbation of PG and cytokine secretion.

Genome-wide identification of microRNAs in decidual natural killer cells from patients with unexplained recurrent spontaneous abortion

PROBLEM

This study revealed miRNA regulation and functional microarray-based profiles of miRNAs in the natural killer (NK) cells of the decidual tissue obtained from patients with unexplained recurrent spontaneous abortion (URSA).

METHOD OF STUDY

Patients with URSA were categorized based on the occurrence of at least two or more successive spontaneous abortions between 7th and 10th gestational week. Total RNA was isolated from the NK cells of the decidual tissue obtained from patients with induced abortion at about the 8th gestational week. The potential contribution of regulatory miRNAs to a genetic predisposition to URSA was characterized by comparison with healthy and fertile controls and bioinformatics analyses.

RESULTS

Analysis of the miRNA expression profiles identified 50 miRNAs that were differentially expressed, including one down-regulated and 49 up-regulated miRNAs in the URSA group. MiRNA-Gene-Network, miRNA-GO-Network and miRNA-Gene-TF-Network were constructed. The key miRNAs, genes, GOs and core TFs in the network were determined.

CONCLUSION

Our results suggest that a close relationship exists between the aberrant miRNAs and URSA. Furthermore, these findings support the notion that altered expression of miRNAs may contribute to the clinical diagnosis of URSA and the potential to develop novel strategies for therapeutic targets against URSA.

Systematic analysis of hsa-miR-363 gene overexpression pattern in endometrial stromal cells

Endometriosis is a benign disease, but has invasion and metastasis characteristics similar to malignant tumors. Clinically, it is a difficult problem of gynecological clinical treatment for its high recurrence rate. It has been confirmed that miR-363 was downregulated in endometriosis tissues and miR-363 overexpression inhibited the invasion ability of endometrial stromal cells (ESCs). In order to explore the potential mechanism of miR-363-reduced ESC migration and invasion progression, we sought to demonstrate the targeted mRNA expression levels of miR-363 through microarray, and performed cluster analysis to identify potential functions of these targeted genes in ESCs. The wound migration assay showed that there was an observable trend of cell migration potential decrease after transfection with hsa-miR-363. The qRT-PCR result showed that compared to miR-363 negative control cell group, miR-363 was upregulated 3,264.58-fold after miR-363 lentiviral transfection in miR-363 mimics group. The microarray data showed that compared to ESCs miR-363 negative control cell group, 249 genes were upregulated in ESCs miR-363 mimics cells group, and 139 genes were downregulated. Gene Ontology analysis and the pathway analysis data demonstrated that these target genes are mainly involved in cell migration, cell adhesion and invasion, proliferation, apoptosis, alteration of endometrial cells and some related signaling pathways. Our study explored the gene expression pattern after miR-363 overexpression, which could expand the insights into the miR-363 function and molecular mechanisms in 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.

The impact of infertility diagnosis on embryo-endometrial dialogue

Initial stages of implantation involve bi-directional molecular crosstalk between the blastocyst and endometrium. This study investigated an association between infertility etiologies, specifically advanced maternal age (AMA) and endometriosis, on the embryo-endometrial molecular dialogue prior to implantation. Co-culture experiments were performed with endometrial epithelial cells (EEC) and cryopreserved day 5 blastocysts (n = 41 ≥ Grade 3BB) donated from patients presenting with AMA or endometriosis, compared to fertile donor oocyte controls. Extracellular vesicles isolated from co-culture supernatant were analyzed for miRNA expression and revealed significant alterations correlating to AMA or endometriosis. Specifically, AMA resulted in 16 miRNAs with increased expression (P ≤ 0.05) and strong evidence for negative regulation toward 206 target genes. VEGFA, a known activator of cell adhesion, displayed decreased expression (P ≤ 0.05), validating negative regulation by 4 of these increased miRNAs: miR-126; 150; 29a; 29b (P ≤ 0.05). In endometriosis patients, a total of 10 significantly altered miRNAs displayed increased expression compared to controls (miR-7b; 9; 24; 34b; 106a; 191; 200b; 200c; 342-3p; 484) (P ≤ 0.05), targeting 1014 strong evidence-based genes. Three target genes of miR-106a (CDKN1A, E2F1 and RUNX1) were independently validated. Functional annotation analysis of miRNA-target genes revealed enriched pathways for both infertility etiologies, including disrupted cell cycle regulation and proliferation (P ≤ 0.05). These extracellular vesicle-bound secreted miRNAs are key transcriptional regulators in embryo-endometrial dialogue and may be prospective biomarkers of implantation success. One of the limitations of this study is that it was a stimulated, in vitro model and therefore may not accurately reflect the in-vivo environment.

miR-205 inhibits cell growth by targeting AKT-mTOR signaling in progesterone-resistant endometrial cancer Ishikawa cells

PURPOSE

miR-205 is significantly up-regulated in endometrioid adenocarcinoma. In this study, the significant anticancer effect of a miR-205 inhibitor was investigated in both endometrial carcinoma and progesterone-resistant endometrial carcinoma cells.

RESULTS

Compared with Ishikawa endometrial cancer cells, miR-205 was expressed at higher levels in a progesterone-resistant (PR) sub-cell line. Inhibition of miR-205 suppressed the growth of cancer cells in a dose- and time-dependent manner. Moreover, the miR-205 inhibitor induced a marked increase in the percentage of Ishikawa-PR cells in G2/M phases and a decrease in the percentage of cells in G0/G1 and S phases. In addition, miR-205 inhibitor-treated tumor cells exhibited increased apoptosis. Moreover, miR-205 was found to negatively regulate PTEN expression and lead to autophagy and activation of the AKT/mTOR pathway in PR cells, and PTEN protein levels significantly decreased with development of progesterone resistance in endometrial cancer cells. Western blot assay showed up-regulated autophagy, as indicated by expression of LC3-II/LC3-I and beclin1, in Ishikawa cells; in particular, autophagy was markedly induced in PR cells treated with the miR-205 inhibitor.

MATERIALS AND METHODS

We measured and analyzed cell growth curves with and without miR-205 inhibition with the MTT assay, miR-205 expression by qRT-PCR, cell cycle and apoptosis using annexin V/propidium iodide staining and flow cytometry, and autophagy, apoptosis, and AKT-mTOR signaling by western blotting.

CONCLUSIONS

Inhibition of miR-205, which targets the AKT-mTOR pathway, in endometrial cancer cells provides a potential, new treatment for PR endometrial carcinoma.

Up-regulation of ribosome biogenesis by MIR196A2 genetic variation promotes endometriosis development and progression

Aberrant miRNA expression has been reported in endometriosis and miRNA gene polymorphisms have been linked to cancer. Because certain ovarian cancers arise from endometriosis, we genotyped seven cancer-related miRNA single nucleotide polymorphisms (MiRSNPs) to investigate their possible roles in endometriosis. Genetic variants in MIR196A2 (rs11614913) and MIR100 (rs1834306) were found to be associated with endometriosis development and related clinical phenotypes, such as infertility and pain. Downstream analysis of the MIR196A2 risk allele revealed upregulation of rRNA editing and protein synthesis genes, suggesting hyper-activation of ribosome biogenesis as a driving force for endometriosis progression. Clinical studies confirmed higher levels of small nucleolar RNAs and ribosomal proteins in atypical endometriosis lesions, and this was more pronounced in the associated ovarian clear cell carcinomas. Treating ovarian clear cells with CX5461, an RNA polymerase I inhibitor, suppressed cell growth and mobility followed by cell cycle arrest at G2/M stage and apoptosis. Our study thus uncovered a novel tumorigenesis pathway triggered by the cancer-related MIR196A2 risk allele during endometriosis development and progression. We suggest that anti-RNA polymerase I therapy may be efficacious for treating endometriosis and associated malignancies.

Early Detection of Preeclampsia Using Circulating Small non-coding RNA

Preeclampsia is one of the most dangerous pregnancy complications, and the leading cause of maternal and perinatal mortality and morbidity. Although the clinical symptoms appear late, its origin is early, and hence detection is feasible already at the first trimester. In the current study, we investigated the abundance of circulating small non-coding RNAs in the plasma of pregnant women in their first trimester, seeking transcripts that best separate the preeclampsia samples from those of healthy pregnant women. To this end, we performed small non-coding RNAs sequencing of 75 preeclampsia and control samples, and identified 25 transcripts that were differentially expressed between preeclampsia and the control groups. Furthermore, we utilized those transcripts and created a pipeline for a supervised classification of preeclampsia. Our pipeline generates a logistic regression model using a 5-fold cross validation on numerous random partitions into training and blind test sets. Using this classification procedure, we achieved an average AUC value of 0.86. These findings suggest the predictive value of circulating small non-coding RNA in the first trimester, warranting further examination, and lay the foundation for producing a novel early non-invasive diagnostic tool for preeclampsia, which could reduce the life-threatening risk for both the mother and fetus.

Preliminary study of microRNA-126 as a novel therapeutic target for primary hypertension

The present study aimed to explore microRNA-126 (miR-126) as a novel therapeutic target for primary hypertension. The lentiviral vector containing human immunodeficiency virus 1 (HIV-1), the miR-126 gene knockdown viral vector (lenti-miR-126-KD), and control lentiviral vector (lenti-scramble-miR) were constructed. Spontaneously hypertensive rats were randomly divided into 4 groups, which received a high dose of lenti-miR-126-KD (1×10⁸, n=5), low dose of lenti-miR-126-KD (1×10⁷, n=6), scramble-miR (5×10⁷, n=6), and PBS (n=6). Lentiviral vectors were injected into the tail vein. Data on the systolic blood pressure, diastolic pressure, mean arterial pressure, and heart rate were collected weekly. After 8 weeks of virus administration, the distribution of lentiviral vectors in different tissues was observed by fluorescence microscopy. Picric acid Sirius red and H&E staining were used to observe the target organ damage, and the ELISA kit was used to determine the serum nitric oxide (NO) content. The lentiviral vector was found to be constructed successfully. Eight weeks after the lentiviral vector injection, green fluorescent protein was observed in different tissues in each group. The blood pressure and heart rate were not significantly altered after lentiviral vector injection (P>0.05). No significant differences in the heart-to-body weight ratio among the four groups were observed (P=0.23). Picric acid Sirius red and H&E staining revealed that there was no significant difference in morphology among the four groups. No significant difference in the serum NO level among the four groups was noted (P=0.23). The miR-126 gene knockdown lentiviral vector was constructed successfully. No significant antihypertensive effect was observed by the knockdown of miR-126 for the treatment of primary hypertension. The target organs were not protected significantly after the treatment. The increased level of miR-126 expression in hypertensive patients may be due to a compensatory mechanism.

Insulin-like growth factor-I induces chemoresistence to docetaxel by inhibiting miR-143 in human prostate cancer

Elevated levels of insulin-like growth factor-I (IGF-I) are associated with carcinogenesis and cancer progression. However, the molecular mechanisms by which IGF-I promotes prostate cancer development remain to be elucidated. Docetaxel chemotherapy is an important therapeutic strategy in many types of human cancers including prostate cancer. In this study, we showed that IGF-I rendered PC-3 and DU145 cells more resistant to docetaxel treatment. IGF-I treatment decreased miR-143 expression, but increased the expression levels of IGF-I receptor (IGF-IR) and insulin receptor substrate 1 (IRS1), direct targets of miR-143. Overexpression of miR-143 abolished IGF-I-induced chemoresistance to docetaxel treatment, decreased expression levels of IGF-I, IRS1, and vascular endothelial growth factor (VEGF) in prostate cancer cell lines. Furthermore, docetaxel treatment significantly inhibited VEGF transcriptional activation, whereas IGF-I treatment induced VEGF transcriptional activation in a dose-dependent manner. Forced expression of IGF-IR and IRS1 cDNAs without the 3’ UTR regions restored miR-143-inhibited VEGF transcriptional activation. Finally, miR-143 inhibited tumor growth and made cells more sensitive to docetaxel treatment for decreasing tumor growth in vivo. Taken together, our data demonstrates that IGF-I induces docetaxel resistance and upregulates IGF-IR and IRS1 expression through miR-143 downregulation, whereas miR-143 acts as a tumor suppressor by targeting its targets IGF-IR and IRS1.

MicroRNA-200c Inhibits Epithelial-Mesenchymal Transition by Targeting the BMI-1 Gene Through the Phospho-AKT Pathway in Endometrial Carcinoma Cells In Vitro

Background

MicroRNA-200c (miR-200c) is a short non-coding RNA that has a role in tumorigenesis and cancer progression. The aims of this study were to investigate the role of miR-200c in cell migration and epithelial-mesenchymal transition (EMT) in endometrial carcinoma cells in vitro.

Material/Methods

Potential direct targets of miR-200c were identified through the TargetScan database. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used study the expression of miR-200c in the endometrial carcinoma cell lines, Ishikawa and JEC, in vitro. Cell migration was studied using transwell assays. Expression of the mesenchymal marker, N-cadherin, the epithelial marker, E-cadherin, the transcription factor, Slug, the BMI-1 protein, AKT, and p-AKT were measured using Western blot. Small interfering RNA (siRNA) was used to silence the BMI-1 gene to study the targeting effect.

Results

Over-expression of miR-200c in Ishikawa and JEC cells resulted in reduced cell migration and proliferation. Western blot showed that overexpression of miR-200c downregulated the expression of the BMI-1 protein, p-AKT, N-cadherin and Slug, and the expression E-cadherin was upregulated; silencing miR-200c reversed these results. Silencing the BMI-1 gene inhibited EMT and suppressed p-AKT in miR-200c-inhibited endometrial carcinoma cells by increasing E-cadherin expression, reducing the expression of N-cadherin and the EMT-associated transcription factor, Slug.

Conclusions

In endometrial carcinoma cells in vitro, miR-200c inhibited EMT by targeting the BMI-1 gene through the p-AKT pathway.

miR-30c may serve a role in endometriosis by targeting plasminogen activator inhibitor-1

The present study aimed to investigate the role of miR-30c in endometriosis (EMs) and the underlying mechanism. The expression of miR-30c and plasminogen activator inhibitor type 1 (PAI-1) mRNA in EMs tissues was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and the expression of PAI-1 protein was detected by western blot analysis. The proliferation, migration, invasion and adhesion of endometrial stromal cells (ESCs) in different groups transfected with miR-30c mimic or inhibitor were compared. It was demonstrated that miR-30c expression in ectopic and eutopic endometriosis tissues were significantly lower than in normal endometrial tissue. However, PAI-1 mRNA expression in ectopic and eutopic endometrial tissues was higher than in normal endometrial tissues. Furthermore, the expression of PAI-1 protein was higher in ectopic and eutopic endometrosis tissues than in normal tissues. RT-qPCR results indicated that miR-30c expression was significantly increased or decreased in ESCs following transfection of mimic or inhibitor of miR-30c, respectively. Overexpression of miR-30c repressed the expression of PAI-1 mRNA and protein, while inhibition of miR-30c upregulated the expression of PAI-1 in ESCs. In addition, the invasion, migration, proliferation and adhesion of ESCs was repressed following the overexpression of miR-30c, whereas they were promoted when miR-30c expression was downregulated. The results of the present study indicated that miR-30c serves an important role in the development and progression of EMs by regulating the expression of PAI-1.

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.

MicroRNA-130b is involved in bovine granulosa and cumulus cells function, oocyte maturation and blastocyst formation

Background

Oocyte maturation and preimplantation embryo development are controlled by array of genes that are post-transcriptionally regulated by microRNAs. With respect to this, previously, we identified altered expression of microRNA-130b (miR-130b) during oocyte maturation. Here, we aimed to investigate the role of miR-130b in bovine granulosa and cumulus cell function, oocyte maturation and preimplantation embryo development using gain- and loss-of- function approach.

Methods

For this study, the granulosa cells, cumulus cells and the oocytes were collected from ovaries obtained from slaughterhouse. The genes targeted by miR-130b were identified using dual-luciferase reporter assay. The role of miR-130b in granulosa and cumulus cell function was investigated by increasing and inhibiting its expression in in vitro cultured cells using miR-130b precursor and inhibitor, respectively while the role of miR-130b on oocyte development, immature oocytes were microinjected with miR-130b precursor and inhibitor and the polar body extrusion, the proportion of oocytes reaching to metaphase II stage and the mitochondrial were determined in each oocyte group 22 h after microinjection. Moreover, to investigate the role of miR-130b during preimplantation embryo development, zygote stage embryos were microinjected with miR-130b precursor or inhibitor and the cleavage rate, morula and blastocyst formation was analyzed in embryos derived from each zygote group after in vitro culture.

Results

The luciferase assay showed that SMAD5 and MSK1 genes were identified as the direct targets of miR-130b. Overexpression of miR-130b increased the granulosa and cumulus cell proliferation, while inhibition showed the opposite phenotype. Apart from these, modulation of miR-130b altered the lactate production and cholesterol biosynthesis in cumulus cells. Furthermore, inhibition of miR-130b expression during oocyte in vitro maturation reduced the first polar body extrusion, the proportion of oocytes reaching to metaphase II stage and the mitochondrial activity, while inhibition of miR-130b during preimplantation embryo development significantly reduced morula and blastocyst formation.

Conclusion

This study demonstrated that in vitro functional modulation of miR-130b affected granulosa and cumulus cell proliferation and survival, oocyte maturation, morula and blastocyst formation suggesting that miR-130b is involved in bovine oocyte maturation and preimplantation embryo development.

Electronic supplementary material

The online version of this article (doi:10.1186/s13048-017-0336-1) contains supplementary material, which is available to authorized users.

Epigenetics in endometrial carcinogenesis - part 2: histone modifications, chromatin remodeling and noncoding RNAs

Carcinogenesis is a multistep multifactorial process that involves the accumulation of genetic and epigenetic alterations. In the past two decades, there has been an exponential growth of knowledge establishing the importance of epigenetic changes in cancer. Our work focused on reviewing the main role of epigenetics in the pathogenesis of endometrial carcinoma, highlighting the reported results concerning each epigenetic mechanistic layer. In a previous review, we assessed DNA methylation alterations. The present review examines the contribution of histone modifications, chromatin remodeling and noncoding RNA alterations for endometrial carcinogenesis.

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.

An integrative transcriptomic analysis reveals bisphenol A exposure-induced dysregulation of microRNA expression in human endometrial cells

Bisphenol A (BPA) are commonly used in the manufacture of polycarbonate plastics. Higher BPA exposure levels have been found in patients with endometrial hyperplasia that is one of risk factors of endometrial cancer (EC). Aberrant microRNAs (miRNAs) regulation has been observed in the development of cancer. Thus, this study investigated whether BPA exposure can disrupt miRNA regulation and its gene expression regarding to EC carcinogenic progress. Microarray experiments of miRNA and mRNA were performed in human endometrial cancer RL95-2 cells with treatment of low-to-moderate (10, 10³ and 10⁵nM) BPA to explore the aberrant genes corresponding to human EC progression. According to the analysis of KEGG pathway and Cytoscape gene network, this study identified that BPA exposure reduced miR-149 expression to down-regulate DNA repair gene ARF6 (ADP-ribosylation factor 6) and tumor protein p53 (TP53), and up-regulate CCNE2 (cyclin E2) potentially to interrupt cell cycle. BPA also increased miR-107 to suppress hedgehog signaling factors, suppressor of fused homolog (SUFU) and GLI family zinc finger 3 (GLI3) to activate hedgehog signaling for cell proliferation underlying carcinogenesis. Furthermore, the BPA-induced cell proliferation was attenuated by transfection with miR-149 mimic and miR-107 inhibitor. These findings provided an insight into potential epigenetic mechanism of BPA exposure on the risk of endometrial carcinogenesis.

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.

The future therapy of endometrial cancer: microRNA's functionality, capability, and putative clinical application

PURPOSE

Endometrial cancer (EC) therapy is characterized by the heterogeneity of EC subtypes resulting in unclear clinical behavior as well as in unsatisfactory treatment options. The available biomarkers, such as cellular tumor antigen p53 (TP53), phosphatidylinositol 3,4,5-trisphosphate 3-phosphatase and dual-specificity protein phosphatase (PTEN), and phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) genes alone might not be sufficient, and thus, new predictive and prognostic biomarkers are urgently required. The biomolecule class of microRNA represents a group of endogenously expressed regulatory factors primarily involved in control of pivotal cancer-related mechanisms including cell cycle, proliferation, apoptosis, and metastasis. Here, we review the current state of science regarding microRNA functionality in EC progression.

miR-9 Acts as an OncomiR in Prostate Cancer through Multiple Pathways That Drive Tumour Progression and Metastasis

Identification of dysregulated microRNAs (miRNAs) in prostate cancer is critical not only for diagnosis, but also differentiation between the aggressive and indolent forms of the disease. miR-9 was identified as an oncomiR through both miRNA panel RT-qPCR as well as high-throughput sequencing analysis of the human P69 prostate cell line as compared to its highly tumorigenic and metastatic subline M12, and found to be consistently upregulated in other prostate cell lines including DU-145 and PC3. While miR-9 has been characterized as dysregulated either as an oncomiR or tumour suppressor in a variety of other cancers including breast, ovarian, and nasopharyngeal carcinomas, it has not been previously evaluated and proven as an oncomiR in prostate cancer. miR-9 was confirmed an oncomiR when found to be overexpressed in tumour tissue as compared to adjacent benign glandular epithelium through laser-capture microdissection of radical prostatectomy biopsies. Inhibition of miR-9 resulted in reduced migratory and invasive potential of the M12 cell line, and reduced tumour growth and metastases in male athymic nude mice. Analysis showed that miR-9 targets e-cadherin and suppressor of cytokine signalling 5 (SOCS5), but not NF-ĸB mRNA. Expression of these proteins was shown to be affected by modulation in expression of miR-9.

Experimental and bioinformatic analysis of cultured Bovine Endometrial Cells (BEND) responding to interferon tau (IFNT)

BACKGROUND

In ruminants, embryo implantation depends on progesterone (P4) and interferon tau (IFNT) controlling endometrial function. IFNT antagonizes bovine endometrial cells (BEND) response to phorbol 12,13-dibutyrate (PDBU) through posttranscriptional regulation of gene expression. We have previously described microRNAs (miRNAs) profiles in bovine endometrium, detecting miR-106a, relevant for embryo maternal communication. In this study, we investigated the expression miR-106a and genes for prostaglandin-endoperoxide synthase 2 (PTGS2), phospholipase A2, group IVA (PLA2G4A), estrogen receptor 1 (ESR1) and progesterone receptor (PR) in response to IFNT in BEND cells and searched for interferon responsive factors (IRFs) binding sites in their promoter genomic regions. The aim of this study was to unravel the molecular mechanisms involved in IFNT signalling and its regulation of miR-106a.

FINDINGS

PTGS2 showed increased expression under PDBU, which was antagonized by IFNT. IFNT induced expression of PR and miR-106a and downregulation of ESR1 and PR. Bioinformatic analyses detected that PLA2G4A was associated to IRF-1 and IRF-6, while ESR1, PR and PTGS2 were associated to only IRF-6. All genes exhibit one motif per IRF, except miR-106a that had three binding sites for IRF-6.

CONCLUSIONS

We report the IFNT regulatory effect on miR-106a expression through IRF-6 in bovine endometrial cells. We identified a set of potential binding sites for IRF-1 and IRF-6 within the bovine genome. A set of candidate gene regions could be characterized where IFNT can act via IRFs to regulate the expression of proteins and miRNAs. Future studies will use these data to detect new IFNT regulatory mechanisms in the endometrium.

Association of miR-34a-3p/5p, miR-141-3p/5p, and miR-24 in Decidual Natural Killer Cells with Unexplained Recurrent Spontaneous Abortion

BACKGROUND

The specific causes of recurrent spontaneous abortion (RSA) remain unknown in 37-79% of affected women. The aim of this study was to explore the expression levels of 6 miRNAs in natural killer (NK) cells from the decidua of patients with unexplained RSA (URSA) and to predict the target genes of 3 miRNAs.

MATERIAL/METHODS

Two groups were examined: URSA (n=20) and controls (n=20). Flow cytometry analysis was used to identify NK cells isolated from the decidua. Transcriptional levels of miRNA were monitored using quantitative real-time reverse transcription-polymerase chain reaction. Prediction and analysis of mRNA targets of differentially expressed miRNAs were performed using bioinformatics methods.

RESULTS

Five miRNAs [miR-34a (+281%, P<0.001), miR-155 (+396%, P<0.001), miR-141 (+142%, P<0.01), miR-125a (+279%, P<0.001), and miR-125b (+185%, P<0.001)] were up-regulated, while miR-24 was down-regulated (-64%, P<0.01) in the URSA group, compared to the control group. This study identified potential miRNA targets: miR-34a-3p/5p, 585/1718 (targets of miR-34a-3p/targets of miR-34a-5p), miR-141-3p/5p, 2270/629 (targets of miR-141-3p/targets of miR-141-5p), and miR-24, 2320 target genes. A total of 140 pathways related to target genes were identified including PI3K-Akt, focal adhesion, MAPK, Wnt, regulation of the actin cytoskeleton, T cell receptor, TGF-β, and estrogen signaling pathways.

CONCLUSIONS

This study suggests that miR-34a-3p/5p, miR-141-3p/5p, and miR-24 in decidual NK cells could be associated with URSA. These findings might contribute to the panel of diagnostic and prognostic biomarkers with clinical utility, and facilitate the development of new strategies for targeted therapy against URSA.

MicroRNA-223-3p suppresses leukemia inhibitory factor expression and pinopodes formation during embryo implantation in mice

MicroRNA (miRNA) regulates gene expression in a post-transcriptional manner, which hybridizes the target mRNAs with complementary sequence and subsequently leads to translation repression or mRNA degradation. Online sequence alignment showed that there is a putative binding site of miR-223-3p on the 3'UTR of LIF, which is considered to be an important marker of endometrial receptivity. Thus, we hypothesized that miR-223-3p may affect embryo implantation by suppressing LIF expression. In this study, we found that miR-223-3p and LIF protein was inversely expressed in the endometrium of mice during implantation window. Then we proved that miR-223-3p directly binds to LIF 3'UTR with luciferase reporter assay and supresses the expression of LIF. To investigate whether miR-233-3p affects embryo implantation, miR-223-3p agonist was injected into the uteri of pregnant mice. The results demonstrated the suppressing effect of miR-223-3p on embryo implantation. Furthermore, over-expression of miR-223-3p was found to compromise pinopodes formation in the endometrium of mice. Taken all together, our findings revealed that miR-223-3p suppresses pinopodes formation and LIF protein expression, which may lead to diminished embryo implantation.