Hypoxia and the endometrium: An indispensable role for HIF-1α as therapeutic strategies

Hypoxia-inducible factor 1 alpha (HIF-1α) is a major molecular mediator of the hypoxic response. In the endometrium, local hypoxic conditions induced by hormonal fluctuations and endometrial vascular remodeling contribute to the production of HIF-1α, which plays an indispensable role in a series of physiological activities, such as menstruation and metamorphosis. The sensitive regulation of HIF-1α maintains the cellular viability and regenerative capacity of the endometrium against cellular stresses induced by hypoxia and excess reactive oxygen species. In contrast, abnormal HIF-1α levels exacerbate the development of various endometrial pathologies. This knowledge opens important possibilities for the development of promising HIF-1α-centered strategies to ameliorate endometrial disease. Nonetheless, additional efforts are required to elucidate the regulatory network of endometrial HIF-1α and promote the applications of HIF-1α-centered strategies in the human endometrium. Here, we summarize the role of the HIF-1α-mediated pathway in endometrial physiology and pathology, highlight the latest HIF-1α-centered strategies for treating endometrial diseases, and improve endometrial receptivity.

Network pharmacological study and in vitro studies validation-Molecular dynamics simulation of Cistanche deserticola in promoting periodontitis and bone remodeling

OBJECTIVE

Periodontitis is a chronic infectious disease, characterized by loss of alveolar bone and supporting tissues. Cistanche deserticola(Cd), a local medicinal herb in Xinjiang, possesses favorable biological characteristics and potential applications. Our aim is to investigate the remodeling properties of Cd extract and elucidate the specific mechanisms underlying its therapeutic effects on periodontitis, by employing a combination of basic experimental and network pharmacology approaches.

METHODS

Firstly, UHPLC-QTOF-MS analysis was conducted on Cd extract to identify its main components, with several compounds were identified by standard. Subsequently, in vitro studies were performed using the Cd extract on MC3T3-E1 cells. Cell proliferation viability was assessed using CCK-8 and apoptosis assays, while ALP and ARS staining and quantitative experiments, qRT-PCR, and Western blot assays were employed to evaluate the osteogenic differentiation capability. Network pharmacology analysis was then carried out using the identified compounds to establish a database of Cd components and targets, along with a database of periodontitis. The intersection of these databases revealed the network relationship between Cd components-mapped genes-signaling pathways. KEGG/GO pathway analysis of the targets was performed to filter potential enriched pathways. PPI/CytoHubba protein interaction network analysis was utilized to identify hub genes. Molecular docking and molecular dynamics simulations were employed to analyze the docking and interaction between core gene and Cd components.

RESULTS

We detected 38 major components in the Cd extract, with Echinacoside, Acteoside, Tubuloside A, and Cistanoside A undergoing standard substance verification. In vitro studies indicated that the Cd, at concentrations below 100 μg/ mL, did not affect cell proliferation and inhibited apoptosis. Osteogenesis assays demonstrated that Cd at concentrations of 1 μg/ mL, 10 μg/ mL, and 100 μg/ mL significantly promoted the osteogenic differentiation ability of MC3T3-E1 cells. It also notably upregulated the mRNA and protein levels of Alp, Bmp2, Runx2, and Opn, and the optimal concentration was 10 μg/mL. Network pharmacology results revealed the network relationship between Cd's components, crossed targets and signaling pathways. Combined with KEGG/GO pathway analysis and PPI/CytoHubba protein interaction network analysis. The key pathway and hub genes of Cd regulating periodontitis are both related to hypoxia pathway and HIF-1α. Molecular docking results showed a strong binding affinity between Cd compounds and hub genes, and molecular dynamics simulation results indicated the stability of the complexes formed between HIF-1α and several Cd compounds.

CONCLUSION

Cistanche deserticola exhibits a notable capacity to promote bone regeneration, and its mechanism of action in regulating periodontitis is associated with the hypoxia signaling pathway. HIF-1α may serve as a potential core gene. Future research will focus on exploring the mechanism of Cd in intervene periodontitis and promoting bone remodeling in hypoxic environment.

Hypoxia-inducible factor in breast cancer: role and target for breast cancer treatment

Globally, breast cancer stands as the most prevalent form of cancer among women. The tumor microenvironment of breast cancer often exhibits hypoxia. Hypoxia-inducible factor 1-alpha, a transcription factor, is found to be overexpressed and activated in breast cancer, playing a pivotal role in the anoxic microenvironment by mediating a series of reactions. Hypoxia-inducible factor 1-alpha is involved in regulating downstream pathways and target genes, which are crucial in hypoxic conditions, including glycolysis, angiogenesis, and metastasis. These processes significantly contribute to breast cancer progression by managing cancer-related activities linked to tumor invasion, metastasis, immune evasion, and drug resistance, resulting in poor prognosis for patients. Consequently, there is a significant interest in Hypoxia-inducible factor 1-alpha as a potential target for cancer therapy. Presently, research on drugs targeting Hypoxia-inducible factor 1-alpha is predominantly in the preclinical phase, highlighting the need for an in-depth understanding of HIF-1α and its regulatory pathway. It is anticipated that the future will see the introduction of effective HIF-1α inhibitors into clinical trials, offering new hope for breast cancer patients. Therefore, this review focuses on the structure and function of HIF-1α, its role in advancing breast cancer, and strategies to combat HIF-1α-dependent drug resistance, underlining its therapeutic potential.

Targeting autophagy drug discovery: Targets, indications and development trends

Autophagy plays a vital role in sustaining cellular homeostasis and its alterations have been implicated in the etiology of many diseases. Drugs development targeting autophagy began decades ago and hundreds of agents were developed, some of which are licensed for the clinical usage. However, no existing intervention specifically aimed at modulating autophagy is available. The obstacles that prevent drug developments come from the complexity of the actual impact of autophagy regulators in disease scenarios. With the development and application of new technologies, several promising categories of compounds for autophagy-based therapy have emerged in recent years. In this paper, the autophagy-targeted drugs based on their targets at various hierarchical sites of the autophagic signaling network, e.g., the upstream and downstream of the autophagosome and the autophagic components with enzyme activities are reviewed and analyzed respectively, with special attention paid to those at preclinical or clinical trials. The drugs tailored to specific autophagy alone and combination with drugs/adjuvant therapies widely used in clinical for various diseases treatments are also emphasized. The emerging drug design and development targeting selective autophagy receptors (SARs) and their related proteins, which would be expected to arrest or reverse the progression of disease in various cancers, inflammation, neurodegeneration, and metabolic disorders, are critically reviewed. And the challenges and perspective in clinically developing autophagy-targeted drugs and possible combinations with other medicine are considered in the review.

HIF-1α and periodontitis: Novel insights linking host-environment interplay to periodontal phenotypes

Periodontitis, the sixth most prevalent epidemic disease globally, profoundly impacts oral aesthetics and masticatory functionality. Hypoxia-inducible factor-1α (HIF-1α), an oxygen-dependent transcriptional activator, has emerged as a pivotal regulator in periodontal tissue and alveolar bone metabolism, exerts critical functions in angiogenesis, erythropoiesis, energy metabolism, and cell fate determination. Numerous essential phenotypes regulated by HIF are intricately associated with bone metabolism in periodontal tissues. Extensive investigations have highlighted the central role of HIF and its downstream target genes and pathways in the coupling of angiogenesis and osteogenesis. Within this concise perspective, we comprehensively review the cellular phenotypic alterations and microenvironmental dynamics linking HIF to periodontitis. We analyze current research on the HIF pathway, elucidating its impact on bone repair and regeneration, while unraveling the involved cellular and molecular mechanisms. Furthermore, we briefly discuss the potential application of targeted interventions aimed at HIF in the field of bone tissue regeneration engineering. This review expands our biological understanding of the intricate relationship between the HIF gene and bone angiogenesis in periodontitis and offers valuable insights for the development of innovative therapies to expedite bone repair and regeneration.

Inflammatory Cytokine-Induced HIF-1 Activation Promotes Epithelial-Mesenchymal Transition in Endometrial Epithelial Cells

The endometrium undergoes repeated proliferation and shedding during the menstrual cycle. Significant changes to this environment include fluctuations in the partial pressure of oxygen, exposure to a high-cytokine environment associated with intrauterine infection, and inflammation. Chronic endometritis is a condition wherein mild inflammation persists in the endometrium and is one of the causes of implantation failure and miscarriage in early pregnancy. It is thought that the invasion of embryos into the endometrium requires epithelial-mesenchymal transition (EMT)-associated changes in the endometrial epithelium. However, the effects of inflammation on the endometrium remain poorly understood. In this study, we investigated the effects of the intrauterine oxygen environment, hypoxia-inducible factor (HIF), and inflammation on the differentiation and function of endometrial epithelial cells. We elucidated the ways in which inflammatory cytokines affect HIF activity and EMT in an immortalized cell line (EM-E6/E7/TERT) derived from endometrial epithelium. Pro-inflammatory cytokines caused significant accumulation of HIF-1α protein, increased HIF-1α mRNA levels, and enhanced hypoxia-induced accumulation of HIF-1α protein. The combined effect of inflammatory cytokines and hypoxia increased the expression of EMT-inducing factors and upregulated cell migration. Our findings indicate that pro-inflammatory factors, including cytokines and LPS, work synergistically with hypoxia to activate HIF-1 and promote EMT in endometrial epithelial cells.

CHIP induces ubiquitination and degradation of HMGB1 to regulate glycolysis in ovarian endometriosis

Ovarian endometriosis is a common gynecological condition that can cause infertility in women of childbearing age. However, the pathogenesis is still unknown. We demonstrate that the carboxyl terminus of Hsc70-interacting protein (CHIP) is a negative regulator in the development of endometriosis and reduces HMGB1 expression in endometriotic cells. Meanwhile, CHIP interacts with HMGB1 and promotes its ubiquitinated degradation, thereby inhibiting aerobic glycolysis and the progression of endometriosis. Furthermore, the CHIP agonist YL-109 effectively suppresses the growth of ectopic endometrium in endometriosis mouse model, which could be a potential therapeutic approach for endometriosis. In conclusion, our data suggest that CHIP may inhibit the development of endometriosis by suppressing the HMGB1-related glycolysis.

Oestrogen-induced epithelial-mesenchymal transition (EMT) in endometriosis: Aetiology of vaginal agenesis in Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome

Endometriosis occurs when endometrial-like tissue forms and grows outside the uterus due to oestrogen-induced epithelial-mesenchymal transition in the female reproductive tract. Factors that suppress this event could become potential therapeutic agents against disease occurrence and progression. However, an overview of these studies is still lacking. This review assessed the impact of a number factors on oestrogen-mediated epithelial-mesenchymal transition in the emergence of several diseases in the female reproductive tract, primarily endometriosis. The association between epithelial-mesenchymal transition and Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome was also investigated. Oestrogen, Wnt4 and epithelial-mesenchymal transition were chosen as keywords in Scopus, PubMed, and Web of Science searches performed on 28th June 2021. Study selection was refined to cancer-irrelevant, English, original articles published between years 2011-2021. The full-text assessment was carried out for topic-related articles after title and abstract screening. Included studies were summarised and assessed for their risk of bias using the Office of Health Assessment and Translation tool. In this review, 10 articles investigating oestrogen and epithelial-mesenchymal transition in the female reproductive tract were summarised and classified into two groups: seven studies under 'factor'-modulated epithelial-mesenchymal transition and three studies under 'factor'-manipulated oestrogen-induced epithelial-mesenchymal transition. The current evidence proposes that epithelial-mesenchymal transition is one of the prime causes of reproductive-related disease. This event could be mediated by distinct stimuli, specifically oestrogen and Wnt4 aberration. The results of this review suggest that oestrogen and Wnt4 participate in epithelial-mesenchymal transition in vaginal epithelial cells in MRKH syndrome, adopting from the theories of endometriosis development, which could therefore serve as a foundation for novel target treatment, specifically related to vaginal epithelialisation, to ensure better surgical outcomes.

Osteopontin Splicing Isoforms Contribute to Endometriotic Proliferation, Migration, and Epithelial-Mesenchymal Transition in Endometrial Epithelial Cells

Osteopontin (OPN) isoforms, including OPNb and OPNc, promote malignancy and may contribute to the pathogenesis of endometriosis, a benign disorder with multiple characteristics resembling malignant tumors. In our experiments, OPNb and OPNc were significantly overexpressed in both endometriosis and adenomyosis compared to the normal endometrium. Upregulation of CD44v and the epithelial-mesenchymal transition (EMT) process was also present in endometriotic lesions. Overexpression of OPNb and OPNc splicing variants in endometriotic cells evoked morphological changes, actin remodeling, cell proliferation, cell migration, and EMT through binding OPN ligand receptors CD44 and αvβ3, subsequently activating the PI3K and NF-ĸB pathways. We elucidated the causal role of OPN splice variants in regulating endometriotic cell growth, which may promote the development of OPN-targeted therapies for patients suffering from endometriotic disorders.

A review of the effects of estrogen and epithelial-mesenchymal transformation on intrauterine adhesion and endometriosis

Uterus transplantation has become an option for women suffering from some form of infertility. Current review discusses key physiological functions of the endometrium requiring the transition of tissue cells between the mesenchyme and epithelial cell phenotype, a process known as epithelial-mesenchymal transition (EMT). Estrogen and EMT play a key role in the pathogenesis and treatment of intrauterine adhesion and endometriosis. There is also a close regulatory relationship between estrogen and EMT, and investigation of this relationship is of great significance for the treatment of endometrial disorders. The present review discusses the effects of estrogen on endometrial dysfunction, with a focus on the relationship between estrogen and EMT in endometrial disorders, taking into consideration the mechanisms by which receptors that regulate their functions and proteins that regulate their local biological functions interact with the factors involved in EMT. In addition, the review summarizes emerging drugs targeting receptors or proteins and provides information on the direction of new therapies for endometrial disorders.

Hypoxia-hindered methylation of PTGIS in endometrial stromal cells accelerates endometriosis progression by inducing CD16- NK-cell differentiation

Prostacyclin (PGI₂) plays key roles in shaping the immune microenvironment and modulating vasodilation, whereas its contribution to endometriosis (EMs) remains largely unclear. Our study suggested that prostacyclin synthase (PTGIS)-dependent PGI₂ signaling was significantly activated in EMs, which was involved in the hypoxic microenvironment of ectopic lesions and deficient methylation status of the PTGIS promoter. Notably, in vitro assays, hypoxia promoted PTGIS expression through DNA methyltransferase 1 (DNMT1)-mediated DNA methylation deficiency in endometrial stromal cells (ESCs); PTGIS overexpression enhanced the adhesive ability of ESCs and led to elevated PGI₂ production, and PGI₂ triggered CD16⁻ (encoded by FCGR3, Fc fragment of IgG receptor IIIa) natural killer (NK)-cell differentiation through PGI₂ receptor (IP, PTGIR) in an ESC/NK-cell coculture system. Our rodent model experiment suggested that treatment with the PGI₂ analog iloprost and adoptive transfer of fcgr3 knockout (fcgr3^−/−) NK cells aggravated EMs progression and that genetic ablation of ptgis (ptgis^−/−) in ectopic lesions and treatment with the PTGIR antagonist RO1138452 partially rescued this outcome. Thus, our findings identified the contribution of PGI₂ to EMs progression via enhancement of the adhesive ability of ESCs and inhibition of the activity of NK cells. We hypothesized that PGI₂ is a target for EMs intervention and provide a rationale for studying pharmacological PTGIR inhibition and PTGIS genetic depletion therapies as therapeutic strategies for EMs.

Inhibiting the activity of a critical enzyme found overexpressed in endometriosis lesions could lead to novel therapeutics. Endometriosis affects around 10 per cent of women of reproductive age globally, yet the condition is poorly understood. Endometriosis lesions are known to be in a hypoxic, or low oxygen, state. Zhao Dong at Tongji University in Shanghai, China, and co-workers used human tissue samples and mouse models to determine the roles of a metabolite called prostacyclin (PGI₂) and its catalytic enzyme (prostacyclin synthase, PTGIS) in endometriosis. PTGIS levels were significantly elevated in hypoxic endometrial cells, triggering the overproduction of PGI₂. This PTGIS/PGI₂ increase enhanced the adhesiveness of the cells, promoting survival of developing lesions. PGI₂ overproduction also triggered abnormal differentiation of a specific group of immune cells called natural killer cells, disrupting the body’s immune response.

Circ_0004712 promotes endometriotic epithelial cell proliferation, migration and invasion by regulating miR-488-3p/ROCK1 axis in vitro

Recent evidence indicates that circular RNAs (circRNAs) play crucial regulatory roles in the pathogenesis and development of endometriosis. Circ_0004712 was found to be differentially expressed in endometriosis. However, the detailed function and mechanism of circ_0004712 in endometriosis are still unclear. Quantitative real-time polymerase chain reaction and Western blot were used for the detection of circ_0004712, miR-488-3p and ROCK1 (Rho Associated Coiled-Coil Containing Protein Kinase 1) levels. In vitro experiments in endometrial endothelial cells were performed by cell counting kit-8, EdU, transwell, wound healing assays, and flow cytometry, respectively. The molecular mechanism of circ_0004712 function was investigated using bioinformatics target predication, dual-luciferase reporter, and RNA immunoprecipitation (RIP) assays. The expression of circ_0004712 was higher in endometriotic endometrial tissues and epithelial cells. Knockdown of circ_0004712 suppressed cell proliferation, migration, invasion, EMT process and induced apoptosis in ectopic endometrial epithelial cells in vitro. Mechanistically, circ_0004712 acted as a ceRNA to sponge miR-488-3p, thus elevating the expression of ROCK1, which was confirmed to be a target of miR-488-3p. Rescue experiments suggested that miR-488-3p inhibition reversed the inhibitory effects of circ_0004712 silencing on cell growth and metastasis. Moreover, miR-488-3p restoration restrained the proliferation and metastasis in ectopic endometrial epithelial cells, which were attenuated by ROCK1 overexpression. Circ_0004712 knockdown suppressed the proliferation and metastasis of ectopic endometrial epithelial cells via miR-488-3p/ROCK1 axis in vitro, suggesting a new insight into the pathogenesis of endometriosis.

Down-regulating HK2 inhibits proliferation of endometrial stromal cells through a noncanonical pathway involving phosphorylation of STAT1 in endometriosis

BACKGROUND

Endometriosis is a benign gynecologic disease that causes chronic pelvic pain, dysmenorrhea and infertility and shares several characteristics with malignant tumors, afflicting women of reproductive age. Hexokinase 2 (HK2) plays an essential role as the first rate-limiting enzyme in the metabolic glycolysis pathway, and its abnormal elevation in tumors is associated with tumor genesis and metastasis. However, the expression and role of HK2 in endometriosis remain unclear.

METHODS

We sequenced the primary endometrial stromal cells from patients with endometrioma and utilized immunohistochemistry, quantitative real-time PCR and western blot to determine the expression of HK2. Then wound healing assays, cell invasion assays, cell proliferation assays were performed to explore the functions of HK2 in endometrial stromal cells. Furthermore, mice models of endometriosis were used to observe the effects of HK2 inhibitors in vivo. Lastly, glycolysis metabolism detection and transcriptome sequencing were carried out in HK2-knockdown endometrial stromal cells to analyze the mechanism of HK2 affecting cell function.

RESULTS

Endometrial stromal cells of endometrioma displayed active glycolysis metabolism and elevated expression of HK2. Downregulating HK2 reduced the migration, invasion and proliferation capacity of endometrial stromal cells. Knockdown of HK2 induced upregulation of signal transducer and activator of transcription 1 (STAT1) and their phosphorylation to attenuate the proliferation of endometrial stromal cells.

CONCLUSIONS

HK2 is associated with the migration, invasion and proliferation of endometrial stromal cells, which might provide new insights into the pathogenesis and treatment of endometriosis.

hsa-miR-340-5p inhibits epithelial–mesenchymal transition in endometriosis by targeting MAP3K2 and inactivating MAPK/ERK signaling

Increasing evidence has verified the indispensable effect of microRNAs (miRNAs) in the biological processes of human diseases, including endometriosis. hsa-miR-340-5p was reported to display a low level in patients with endometriosis, but the detailed function of miR-340-5p in endometriosis is unclarified. RT-qPCR was used for the assessment of RNA levels of miR-340-5p and its downstream target genes in endometrial stromal cells (ESCs). Western blotting and Transwell assays revealed that upregulation of miR-340-5p suppressed the migration, invasiveness, and epithelial–mesenchymal transition (EMT) in ESCs. Bioinformatics tools were used to predict miR-340-5p downstream genes. Luciferase reporter assay displayed that miR-340-5p could bind to messenger RNA mitogen-activated protein kinase kinase kinase 2 (MAP3K2). MAP3K2 was targeted by miR-349-5p and could reverse the influence of miR-340-5p. miR-340-5p exerted its impact on the invasive characters of ESCs by inactivating the MAP3K2-mediated MAPK/ERK signaling. In conclusion, miR-340-5p restrains cell migration, invasiveness, and EMT in ESCs by targeting MAP3K2 and inactivating MAPK/ERK signaling.

Iron overload inhibits cell proliferation and promotes autophagy via PARP1/SIRT1 signaling in endometriosis and adenomyosis

Emerging evidence suggests that excess iron accumulates in endometriotic and adenomyotic lesions. However, the role iron overload plays in the pathogenesis of endometriosis or adenomyosis remains unknown. Primary human eutopic endometrial stromal cells (EuESCs) from endometriosis or adenomyosis patients were used as the in vitro model of endometriosis or adenomyosis in this study. We found that iron, manifesting as ferric ammonium citrate (FAC; 0.05-4.8 mM), significantly inhibited cell growth, induced oxidative stress through the Fenton reaction, and functionally activated autophagy in EuESCs, as measured by 5-ethynyl-2'-deoxyuridine incorporation assay, MitoSOX™ Red staining, LC3 turnover assay, and tandem mCherry-eGFP-LC3B fluorescence microscopy. Immunohistochemistry analysis of Ki67 expression in proliferative-phase endometrial tissues revealed that cell proliferation in ectopic tissues was dramatically compromised, suggesting that iron overload may play a role in cell growth inhibition in vivo. We observed that autophagy may alleviate the FAC-induced inhibition of endometrial stromal cell proliferation. Furthermore, sequential FAC (0.8 mM, 24 h) and hydrogen peroxide (H₂O₂; 300 μM, 2 h) treatment successfully induced the Fenton reaction in EuESCs and caused extensive apoptosis, whereas the disruption of autophagy by the knockdown of BECN1 further aggravated cell death. MitoSOX™ Red staining showed that autophagy may promote the survival of EuESCs by decreasing of the Fenton reaction-induced reactive oxygen species generation. In addition, we observed that the Fenton reaction-induced oxidative stress significantly suppressed iron overload-induced autophagy. Moreover, we found that FAC treatment impaired poly(ADP-ribose)-polymerase 1 (PARP1) expression while simultaneously upregulating SIRT1 expression in EuESCs. Our data further showed that PARP1 expression decreased in endometriotic lesions, which may partially result from iron overload. We also found that PARP1 inhibition aggravated iron overload-induced cell growth suppression, and was implicated in iron overload-induced autophagy. In addition, SIRT1 silencing alleviated iron overload-induced PARP1 downregulation and autophagy activation. Overall, our data suggest that iron overload in endometrial stromal cells of endometriotic or adenomyotic lesions may be involved in the inhibition of cell proliferation, simultaneously with the activation of protective autophagy via PARP1/SIRT1 signaling.

Exploring Epithelial-Mesenchymal Transition Signals in Endometriosis Diagnosis and In Vitro Fertilization Outcomes

Endometriosis (EMS) pathogenesis has been related to the release of inflammatory mediators in peritoneal fluid, creating an altered microenvironment that leads to low-grade oocyte/embryos and to the reduction of implantation rates. The Epithelial–Mesenchymal Transition (EMT), an inflammation-related process, can be a further contributing factor to EMS. This study aimed to investigate, among various cytokines and EMT markers (Cadherins, TGF-β, HIF-1α), diagnostic markers of EMS and prognostic factors of in vitro fertilization (IVF) outcomes. Herein, EMS patients manifested higher serum levels of the inflammatory molecules IL-6, IL-8, and IL-12 and a decrease in the concentrations of the anti-inflammatory IL-10. Moreover, biochemical markers associated with the EMT process were more elevated in serum and follicular fluid (FF) of EMS patients than in controls. At the end, the number of good-quality embryos was inversely related to serum IL-6 and EMT markers. Interestingly, serum IL-6 and FF IL-10 concentrations differentiated EMS patients from controls. Finally, serum IL-8 and E-Cadherin levels, as well as FF IL-10, predicted positive IVF outcome with great accuracy. Our data confirm the pivotal role of inflammatory mediators (i.e., IL-6 and IL-10) in EMS pathogenesis and suggest that EMT-related markers are elevated in EMS patients and can be predictive of IVF outcome.

Epithelial-mesenchymal transition: Insights into nickel-induced lung diseases

Nickel compounds are environmental toxicants, prevalent in the atmosphere due to their widespread use in several industrial processes, extensive consumption of nickel containing products, as well as burning of fossil fuels. Exposure to nickel is associated with a multitude of chronic inflammatory lung diseases including asthma, chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis. In addition, nickel exposure is implicated in the development of nasal and lung cancers. Interestingly, a common pathogenic mechanism underlying the development of diseases associated with nickel exposure is epithelial-mesenchymal transition (EMT). EMT is a process by which the epithelial cells lose their junctions and polarity and acquire mesenchymal traits, including increased ability to migrate and invade. EMT is a normal and essential physiological process involved in differentiation, development and wound healing. However, EMT also contributes to a number of pathological conditions, including fibrosis, cancer and metastasis. Growing evidence suggest that EMT induction could be an important outcome of nickel exposure. In this review, we discuss the role of EMT in nickel-induced lung diseases and the mechanisms associated with EMT induction by nickel exposure.

Pathogenesis of Endometriosis: New Insights into Prospective Therapies

Endometriosis is a female reproductive disorder characterized by growth of uterine cells and tissue in distant sites. Around 2-10% of women experience this condition during reproductive age, 35-50% of whom encounter fertility issues or pain. To date, there are no established methods for its early diagnosis and treatment, other than surgical procedures and scans. It is difficult to identify the disease at its onset, unless symptoms such as infertility and/or pain are present. Determining the mechanisms involved in its pathogenesis is vital, not only to pave the way for early identification, but also for disease management and development of less invasive but successful treatment strategies. Endometriosis is characterized by cell proliferation, propagation, evasion of immunosurveillance, and invasive metastasis. This review reports the underlying mechanisms that are individually or collectively responsible for disease establishment and evolution. Treatment of endometriosis mainly involves hormone therapies, which may be undesirable or have their own repercussions. It is therefore important to devise alternative strategies that are both effective and cause fewer side effects. Use of phytochemicals may be one of them. This review focuses on pharmacological inhibitors that can be therapeutically investigated in terms of their effects on signaling pathways and/or mechanisms involved in the pathogenesis of endometriosis.

Oxygen and metabolic reprogramming in the tumor microenvironment influences metastasis homing

Tumor metastasis is the leading cause of cancer mortality, often characterized by abnormal cell growth and invasion to distant organs. The cancer invasion due to epithelial to mesenchymal transition is affected by metabolic and oxygen availability in the tumor-associated micro-environment. A precise alteration in oxygen and metabolic signaling between healthy and metastatic cells is a substantial probe for understanding tumor progression and metastasis. Molecular heterogeneity in the tumor microenvironment help to sustain the metastatic cell growth during their survival shift from low to high metabolic-oxygen-rich sites and reinforces the metastatic events. This review highlighted the crucial role of oxygen and metabolites in metastatic progression and exemplified the role of metabolic rewiring and oxygen availability in cancer cell adaptation. Furthermore, we have also addressed potential applications of altered oxygen and metabolic networking with tumor type that could be a signature pattern to assess tumor growth and chemotherapeutics efficacy in managing cancer metastasis.

Menstruation Dysregulation and Endometriosis Development

Endometriosis is a common gynecological condition characterized by the growth of endometrial-like tissue outside of the uterus which may cause symptoms such as chronic pelvic pain or subfertility. Several surgical and medical therapies are available to manage symptoms, but a cure has yet to be determined which can be attributed to the incomplete understanding of disease pathogenesis. Sampson's theory of retrograde menstruation is a widely accepted theory describing how shed endometrial tissue can enter the peritoneal cavity, but other factors are likely at play to facilitate the establishment of endometriosis lesions. This review summarizes literature that has explored how dysregulation of menstruation can contribute to the pathogenesis of endometriosis such as dysregulation of inflammatory mediators, aberrant endometrial matrix metalloproteinase expression, hypoxic stress, and reduced apoptosis. Overall, many of these factors have overlapping pathways which can prolong the survival of shed endometrial debris, increase tissue migration, and facilitate implantation of endometrial tissue at ectopic sites. Moreover, some of these changes are also implicated in abnormal uterine bleeding and endometrial diseases. More research is needed to better understand the underlying mechanisms driving dysregulation of menstruation in endometriosis specifically and identifying specific pathways could introduce new treatment targets. Analyzing menstrual fluid from women with endometriosis for inflammatory markers and other biomarkers may also be beneficial for earlier diagnosis and disease staging.

Stationed or Relocating: The Seesawing EMT/MET Determinants from Embryonic Development to Cancer Metastasis

Epithelial and mesenchymal transition mechanisms continue to occur during the cell cycle and throughout human development from the embryo stage to death. In embryo development, epithelial-mesenchymal transition (EMT) can be divided into three essential steps. First, endoderm, mesoderm, and neural crest cells form, then the cells are subdivided, and finally, cardiac valve formation occurs. After the embryonic period, the human body will be subjected to ongoing mechanical stress or injury. The formation of a wound requires EMT to recruit fibroblasts to generate granulation tissues, repair the wound and re-create an intact skin barrier. However, once cells transform into a malignant tumor, the tumor cells acquire the characteristic of immortality. Local cell growth with no growth inhibition creates a solid tumor. If the tumor cannot obtain enough nutrition in situ, the tumor cells will undergo EMT and invade the basal membrane of nearby blood vessels. The tumor cells are transported through the bloodstream to secondary sites and then begin to form colonies and undergo reverse EMT, the so-called "mesenchymal-epithelial transition (MET)." This dynamic change involves cell morphology, environmental conditions, and external stimuli. Therefore, in this manuscript, the similarities and differences between EMT and MET will be dissected from embryonic development to the stage of cancer metastasis.

Inhibition of METTL3/m6A/miR126 promotes the migration and invasion of endometrial stromal cells in endometriosis

N6-methyladenosine (m6A), one of the most abundant RNA modifications, is involved in the progression of many diseases, but its role and related molecular mechanisms in endometriosis remain unknown. To address these issues, we detected m6A levels in normal, eutopic and ectopic endometrium and found the m6A levels decreased in eutopic and ectopic endometrium compared with normal endometrium. In addition, we proved that methyltransferase-like 3 (METTL3) downregulation accounted for m6A reduction in endometriosis. Furthermore, we observed that METTL3 knockdown facilitated the migration and invasion of human endometrial stromal cells (HESCs), while METTL3 overexpression exerted opposite effects, suggesting that METTL3 downregulation might contribute to endometriosis development by enhancing cellular migration and invasion. Mechanistically, METTL3-dependent m6A was involved in the DGCR8-mediated maturation of primary microRNA126 (miR126, pri-miR126). Moreover, miR126 inhibitor significantly enhanced the migration and invasion of METTL3-overexpressing HESCs, whereas miR126 mimics attenuated the migration and invasion of METTL3-silenced HESCs. Our study revealed the METTL3/m6A/miR126 pathway, whose inhibition might contribute to endometriosis development by enhancing cellular migration and invasion. It also showed that METTL3 might be a novel diagnostic biomarker and therapeutic target for endometriosis.

Women with polycystic ovary syndrome present with altered endometrial expression of stanniocalcin-1†

Stanniocalcin-1 (STC-1) is a pro-survival factor that protects tissues against stressors, such as hypoxia and inflammation. STC-1 is co-expressed with the endometrial receptivity markers, and recently endometrial STC-1 was reported to be dysregulated in endometriosis, a condition linked with endometrial progesterone resistance and inflammation. These features are also common in the endometrium in women with polycystic ovary syndrome (PCOS), the most common endocrine disorder in women. Given that women with PCOS present with subfertility, pregnancy complications, and increased risk for endometrial cancer, we investigated endometrial STC-1 expression in affected women. Endometrial biopsy samples were obtained from women with PCOS and controls, including samples from overweight/obese women with PCOS before and after a 3-month lifestyle intervention. A total of 98 PCOS and 85 control samples were used in immunohistochemistry, reverse-transcription polymerase chain reaction, or in vitro cell culture. STC-1 expression was analyzed at different cycle phases and in endometrial stromal cells (eSCs) after steroid hormone exposure. The eSCs were also challenged with 8-bromo-cAMP and hypoxia for STC-1 expression. The findings indicate that STC-1 expression is not steroid hormone mediated although secretory-phase STC-1 expression was blunted in PCOS. Lower expression seems to be related to attenuated STC-1 response to stressors in PCOS eSCs, shown as downregulation of protein kinase A activity. The 3-month lifestyle intervention did not restore STC-1 expression in PCOS endometrium. More studies are warranted to further elucidate the mechanisms behind the altered endometrial STC-1 expression and rescue mechanism in the PCOS endometrium.

Endometrial epithelial-mesenchymal transition (EMT) by menstruation-related inflammatory factors during hypoxia

Endometriosis is characterised by inflammation and fibrotic changes. Our previous study using a mouse model showed that proinflammatory factors present in peritoneal haemorrhage exacerbated inflammation in endometriosis-like grafts, at least in part through the activation of prostaglandin (PG) E2 receptor and protease-activated receptor (PAR). In addition, hypoxia is a well-known inducer of fibrosis that may be associated with epithelial-mesenchymal transition (EMT). However, the complex molecular interactions between hypoxia and proinflammatory menstruation-related factors, PGE2 and thrombin, a PAR1 agonist, on EMT in endometriosis have not been fully characterised. To explore the effects of hypoxia and proinflammatory factors on EMT-like changes in endometrial cells, we determined the effects of PGE2 and thrombin (P/T) on EMT marker expression and cell migration in three dimensional cultured human endometrial epithelial cells (EECs) and endometrial stromal cells (ESCs). Treatment of EECs with P/T under hypoxia stimulated cell migration, increased the expression of mesenchymal N-cadherin, vimentin and C-X-C chemokine receptor type 4 (CXCR4), and reduced the expression of epithelial E-cadherin. Furthermore, treatment with C-X-C motif chemokine ligand 12 (CXCL12), a ligand for CXCR4, increased EMT marker expression and cell migration. In ESCs, P/T or oestrogen treatment under hypoxic conditions increased the expression and secretion of CXCL12. Taken together, our data show that hypoxic and proinflammatory stimuli induce EMT, cell migration and inflammation in EECs, which was increased by CXCL12 derived from ESCs. These data imply that inflammatory mediators in retrograde menstrual fluid contribute to ectopic endometrial EMT and migration in the presence of peritoneal hypoxia.

Ovarian endometriosis, a precursor of ovarian cancer: Histological aspects, gene expression and microRNA alterations (Review)

Ovarian endometriosis is a frequent chronic gynecological disease with an uncertain evolution regarding its progression or association with ovarian malignant lesions. The present review summarized the histological aspects, gene expression and microRNA (miRNA/miR) alterations associated with ovarian endometriosis and cancer and their possible interaction. The endometriosis-ovarian cancer interaction has been proposed by certain researchers as a single entity. Histological results indicated that endometriosis has been in different circumstances coexisting with ovarian cancer, with reference to endometrioid and clear cell carcinoma. Endometriosis with moderate and severe atypia can influence cell proliferation and architecture, resulting in a possible malignant transformation. Gene expression analysis indicated that the pathologies of both endometriosis and ovarian cancer are characterized by genetic instability from a molecular point of view, as several important genetic mutations, including ARID1A, PI3KCA, PTEN, BRCA1, BRCA2, TP53 and KRAS genes, were identified. miRNA alterations have been implicated in the regulation of gene expression. Common dysregulated miRNAs, such as miR-331, miR-335, miR-891, miR-548, miR-124, miR-148, miR-215, miR-192, miR-337, miR-153, miR-155, miR-144, miR-221 and miR-3688 were extensively investigated in understanding endometriosis and ovarian cancer evolution. From a combined viewpoint including histological aspects, gene expression and miRNA alterations, it is reasonable to speculate that endometriosis is associated with ovarian cancer. Ovarian endometriosis lesions may present a risk for ovarian malignant lesions, which supports a model of endometriosis as a malignant precursor. However, the endometriosis-ovarian cancer association is not widely accepted in the literature and additional studies are required to validate this association.

Recepteur d'origine nantais contributes to the development of endometriosis via promoting epithelial-mesenchymal transition of a endometrial epithelial cells

Endometriosis is a benign, chronic inflammatory disease that commonly occurs in reproductive‐aged women. Epithelial‐mesenchymal transition (EMT) of endometrial epithelial cells plays an important role in the development of endometriosis. Recepteur d'origine nantais (RON), a receptor tyrosine kinase, has been reported to promote EMT and progression in tumours. However, whether and how RON mediates the EMT and endometriosis development is not known. Here, we found that RON activation could improve the migratory and invasive capabilities, change cellular morphologies, and decrease expression of E‐cadherin and increase expression of N‐cadherin in endometrial epithelial cells. Inhibition or knockdown of RON expression suppressed the migration and invasion of endometrial epithelial cells. Our studies also indicated that RON played its part in endometrial epithelial cells through protein kinase B (Akt) and mitogen‐activated protein kinase (MAPK) pathways. Treatment with a RON inhibitor could decrease the number of ectopic lesions in a mouse model of endometriosis and mediate expression of EMT markers in endometriotic lesions. These data suggest that RON contributed to endometriosis development by promoting EMT of endometrial epithelial cells. Therefore, RON may be a new therapeutic target for endometriosis.

Tumor necrosis factor receptor type 1-associated death domain (TRADD) regulates epithelial-mesenchymal transition (EMT), M1/M2 macrophage polarization and ectopic endometrial cysts formation in endometriosis

Background

Endometriosis is a gynecological non-malignant disease that is manifested by the presence of extrauterine ectopic endometrial cells and stroma. The aim of current study was to explore the role of tumor necrosis factor receptor type 1-associated death domain (TRADD) protein in endometriosis.

Methods

Cell migration, invasion, and the expression of epithelial-mesenchymal transition (EMT) inducers in TRADD silencing or overexpression in eutopic endometrial stromal cells (EuSCs) and ectopic endometrial stromal cells (EcSCs) were analyzed by wound healing assay, transwell assay, quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blotting and rat endometriosis model. A cell line derived from THP-1 macrophages was used to measure M1/M2 polarization in endometriosis by flow cytometry and enzyme-linked immunosorbent assay (ELISA).

Results

The mRNA level and protein expression of TRADD, keratin, E-cadherin, N-cadherin, vascular endothelial growth factor, matrix metalloproteinase-9, CD40, and CD206 were abnormally expressed in ectopic endometrial tissues and EcSCs. TRADD silencing promoted migration, invasion, and EMT in EuSCs, while TRADD overexpression restrained migration, invasion, and EMT in EcSCs. TRADD knockdown prohibited M1/M2 polarization in normal endometrial homogenization-treated THP-1-derived macrophages, whereas TRADD upregulation facilitated M1/M2 polarization in patients with endometrial homogenization-treated THP-1-derived macrophages. In addition, TRADD overexpression suppressed ectopic endometrial cysts formation in a rat endometriosis model. TRADD overexpression activated NF-κB and MAPK signaling in EcSCs and rat models.

Conclusions

Our results indicated that the overexpression of TRADD prohibited migration, invasion, EMT, M1/M2 polarization and ectopic endometrial cysts formation in endometriosis, and this might due to regulating NF-κB and MAPK signaling.

Current and Future Roles of Circular RNAs in Normal and Pathological Endometrium

The uterine endometrium, which lines the mammalian uterus, is essential for embryo implantation. This lining undergoes significant changes during sexual and menstrual cycles. The endometrium is also associated with hormone-related diseases such as endometriosis and endometrial cancer. Circular RNAs (circRNAs) play a role in various biological processes. Recent studies have determined that circRNAs function in both normal and pathological endometrial environments. Here, we review high-throughput studies pertaining to circRNAs as well as individual circRNAs active in the endometrium, in order to explore the myriad functions of circRNAs in the endometrium and mechanisms underlying these functions, from panoramic and individual perspectives. Owing to their abundant expression, stability, and small size, circRNAs have displayed potential usefulness as diagnostic markers and treatment targets for endometrial-related diseases. Therefore, the specific role of circRNAs in the endometrium warrants systematic investigation in the future.

MTA1, a Target of Resveratrol, Promotes Epithelial-Mesenchymal Transition of Endometriosis via ZEB2

Endometriosis is a benign disease that shares some malignant features. Epithelial-mesenchymal transition (EMT) is involved in the pathogenesis of endometriosis. Metastasis-associated protein 1 (MTA1) plays an important role in various cancers by promoting EMT, yet there are no studies on its function in endometriosis. In the present study, we found that MTA1 was highly expressed in the ectopic endometrium of endometriosis patients and that the expression of MTA1 was related to the revised American Fertility Society stage. MTA1 facilitated endometrial stroma cell proliferation, migration, and invasion by inducing EMT, and the promotion function and MTA1 expression were suppressed by resveratrol, a natural polyphenol. Moreover, we revealed that MTA1 induced EMT through interaction with ZEB2. The findings in a mouse endometriosis model further showed that MTA1 and ZEB2 were upregulated in ectopic tissues and that resveratrol inhibited the growth of ectopic lesions and expression of MTA1 and ZEB2. Taken together, we demonstrate that MTA1 is a protein that promotes EMT via interacting with ZEB2 in the pathogenesis of endometriosis, and may be a target of resveratrol.

HIF-1α is a Potential Molecular Target for Herbal Medicine to Treat Diseases

HIF-1α is an important factor regulating oxygen balance in mammals, and its expression is closely related to various physiological and pathological conditions of the body. Because HIF-1α plays an important role in the occurrence and development of cancer and other diseases, it has become an enduring research hotspot. At the same time, natural medicines and traditional Chinese medicine compounds have amazing curative effects in various diseases related to HIF-1 subtype due to their unique pharmacological effects and more effective ingredients. Therefore, in this article, we first outline the structure of HIF-1α and the regulation related to its expression, then introduce various diseases closely related to HIF-1α, and finally focus on the regulation of natural medicines and compound Chinese medicines through various pathways. This will help us understand HIF-1α systematically, and use HIF-1α as a target to discover more natural medicines and traditional Chinese medicines that can treat related diseases.

Mesothelial Cells Participate in Endometriosis Fibrogenesis Through Platelet-Induced Mesothelial-Mesenchymal Transition

CONTEXT

While fibrosis in endometriosis has recently loomed prominently, the sources of myofibroblasts, the principal effector cell in fibrotic diseases, remain largely obscure. Mesothelial cells (MCs) can be converted into myofibroblasts through mesothelial-mesenchymal transition (MMT) in many fibrotic diseases and adhesion.

OBJECTIVE

To evaluate whether MCs contribute to the progression and fibrogenesis in endometriosis through MMT.

SETTING, DESIGN, PATIENTS, INTERVENTION, AND MAIN OUTCOME MEASURES

Dual immunofluorescence staining and immunohistochemistry using antibodies against calretinin, Wilms' tumor-1 (WT-1), and α-smooth muscle actin (α-SMA) were performed on lesion samples from 30 patients each with ovarian endometrioma (OE) and deep endometriosis (DE), and 30 normal endometrial (NE) tissue samples. Human pleural and peritoneal MCs were co-cultured with activated platelets or control medium with and without neutralization of transforming growth factor β1 (TGF-β1) and/or platelet-derived growth factor receptor (PDGFR) and their morphology, proliferation, and expression levels of genes and proteins known to be involved in MMT were evaluated, along with their migratory and invasive propensity, contractility, and collagen production.

RESULTS

The number of calretinin/WT-1 and α-SMA dual-positive fibroblasts in OE/DE lesions was significantly higher than NE samples. The extent of lesional fibrosis correlated positively with the lesional α-SMA staining levels. Human MCs co-cultured with activated platelets acquire a morphology suggestive of MMT, concomitant with increased proliferation, loss of calretinin expression, and marked increase in expression of mesenchymal markers. These changes coincided with functional differentiation as reflected by increased migratory and invasive capacity, contractility, and collagen production. Neutralization of TGF-β1 and PDGFR signaling abolished platelet-induced MMT in MCs.

CONCLUSIONS

MCs contribute to lesional progression and fibrosis through platelet-induced MMT.

TET1 may contribute to hypoxia-induced epithelial to mesenchymal transition of endometrial epithelial cells in endometriosis

Background

Endometriosis (EMs) is a non-malignant gynecological disease, whose pathogenesis remains to be clarified. Recent studies have found that hypoxia induces epithelial-mesenchymal transition (EMT) as well as epigenetic modification in EMs. However, the relationship between EMT and demethylation modification under hypoxia status in EMs remains unknown.

Methods

The expression of N-cadherin, E-cadherin and TET1 in normal endometria, eutopic endometria and ovarian endometriomas was assessed by immunohistochemistry and immunofluorescence double staining. 5-hmC was detected by fluorescence-based ELISA kit using a specific 5-hmC antibody. Overexpression and inhibition of TET1 or hypoxia-inducible factor 2α (HIF-2α) were performed by plasmid and siRNA transfection. The expression of HIF-2α, TET1 and EMT markers in Ishikawa (ISK) cells (widely used as endometrial epithelial cells) was evaluated by western blotting. The interaction of HIF-2α and TET1 was analyzed by chromatin immunoprecipitation.

Results

Demethylation enzyme TET1 (ten-eleven translocation1) was elevated in glandular epithelium of ovarian endometrioma, along with the activation of EMT (increased expression of N-cadherin, and decreased expression of E-cadherin) and global increase of epigenetic modification marker 5-hmC(5-hydroxymethylcytosine). Besides, endometriosis lesions had more TET1 and N-cadherin co-localized cells. Further study showed that ISK cells exhibited enhanced EMT, and increased expression of TET1 and HIF-2α under hypoxic condition. Hypoxia-induced EMT was partly regulated by TET1 and HIF-2α. HIF-2α inhibition mitigated TET1 expression changes provoked by hypoxia.

Conclusions

Hypoxia induces the expression of TET1 regulated by HIF-2α, thus may promote EMT in endometriosis.

Circular RNA as a potential diagnostic and/or therapeutic target for endometriosis

Endometriosis is a pathology form of endometrium that behaves in a similar way to malignancies, such as invasion and resistance to apoptosis. Circular RNAs (CircRNAs) are a class of noncoding RNAs that have several biological functions including, miRNA sponging, sequestering of proteins, enhancing parental gene expression and translation resulting in polypeptides. In this review, we highlighted the roles of circRNAs as potential diagnostic and therapeutic biomarkers in endometriosis. Moreover, we summarized the roles of circRNAs in the pathogenesis of endometriosis via different signaling pathways, such as the miRNA network and apoptosis.

The expression of hypoxia-inducible factor-1 alpha in primary reproductive organs of the female yak (Bos grunniens) at different reproductive stages

The yak (Bos grunniens) is the most important livestock animal in high-altitude regions owing to its prominent adaptability to cold conditions, nutritional deficiencies and hypoxia. The reproductive organs exhibit different histological appearances and physiological processes at different reproductive stages. Hypoxia-inducible factor-1 alpha (HIF-1α) is the regulatory subunit of HIF-1 that crucially regulates the response to hypoxia in mammalian organisms. The goal of our study was to investigate the expression and distribution of HIF-1α in the primary yak reproductive organs at different reproductive stages. Samples of the ovary, oviduct and uterus of 15 adult female yaks were collected and used in the experiment. The expression and localization of HIF-1α proteins and mRNA were investigated using quantitative real-time polymerase chain reaction (qRT-PCR), Western blot (WB) and immunohistochemistry (IHC). The results indicated that the expression of HIF-1α protein in the ovary was higher during the luteal phase than during the follicular phase and gestation period (p < .05). In the oviduct, HIF-1α protein was also more highly expressed during the luteal phase than during the follicular phase and gestation period (p < .01). However, in the uterus, the HIF-1α protein had stronger expression during the gestation period than during the follicular phase (p < .01) and luteal phase (p < .05). The expression of HIF-1α mRNA was similar to that of its protein. Immunohistochemical analysis revealed intense immunostaining of HIF-1α proteins in the follicular granulosa cells, granular luteal cells, villous epithelial cells of the oviduct, endometrial glandular epithelium and luminal epithelium, foetal villous trophoblast, and epithelia of caruncular crypts. This study showed that the expression of HIF-1α in the ovary, oviduct and uterus varies according to the stage of the reproductive cycle. This implies that HIF-1α plays an important role in regulating the stage-specific physiological function of yak reproductive organs under hypoxic environments.

Focal adenomyosis of the outer myometrium and deep infiltrating endometriosis severity

OBJECTIVE

To determine whether the presence of focal adenomyosis of the outer myometrium (FAOM) at preoperative magnetic resonance imaging is associated with the severity of deep infiltrating endometriosis.

DESIGN

Observational cross-sectional study involving 255 symptomatic deep infiltrating endometriosis patients. Comparisons were performed according to the presence of FAOM.

SETTING

University hospital.

PATIENT(S)

Women with a preoperative magnetic resonance imaging and complete surgical exeresis of endometriotic lesions with histologically documented deep infiltrating endometriosis.

INTERVENTION(S)

Surgical management for deep infiltrating endometriosis.

MAIN OUTCOME MEASURE(S)

The presence of multiple deep infiltrating endometriosis lesions, the mean number and location of deep infiltrating endometriosis lesions, and the mean total revised American Society for Reproductive Medicine scores.

RESULT(S)

The prevalence of FAOM at preoperative magnetic resonance imaging in the 255 patients with deep infiltrating endometriosis was 56.5%. The mean number of deep infiltrating endometriosis lesions was significantly higher in the FAOM(+) group than in the FAOM(-) group: 3.5 ± 2.1 vs. 2.2 ± 1.5. The mean total revised American Society for Reproductive Medicine score was higher in case of FOAM coexisting with deep infiltrating endometriosis. After adjusting for confounding factors, the presence of FAOM was significantly associated with multiple deep lesions.

CONCLUSION(S)

FAOM was significantly associated with greater deep infiltrating endometriosis severity. This needs to be integrated into the management strategy. Furthermore, a pathogenic link between deep infiltrating endometriosis and FAOM cannot be excluded.

CircATRNL1 promotes epithelial-mesenchymal transition in endometriosis by upregulating Yes-associated protein 1 in vitro

Endometriosis is a common and benign gynecological disorder but exhibits malignant features. However, the underlying pathogenesis and pathophysiology of endometriosis remain unclear. Circular RNAs have been demonstrated to participate in the occurrence and progression of multiple diseases. This study was aimed to explore the roles of circATRNL1 in endometriosis in vitro. Based on the results of reverse transcription-quantitative polymerase chain reaction analysis, we found significant upregulation of circATRNL1 and Yes-associated protein 1 (YAP1), while downregulation of miR-141-3p and miR-200a-3p in ectopic tissues compared to eutopic tissues. The immunohistochemistry and western blot analysis showed differentially expressed epithelial-mesenchymal transition (EMT) markers between EuEM and EcEM tissues. The in vitro assays indicated that overexpression of circATRNL1 could promote the proliferation, migration, and invasion of Ishikawa cells, and induce EMT process, while circATRNL1 silencing showed the opposite effect. The mechanical investigation indicated that circATRNL1 upregulated YAP1 by sponging miR-141-3p and miR-200a-3p. Gain-of-function assays validated the inhibitory function of miR-141-3p and miR-200a-3p in endometriosis. The results of rescue assays confirmed the function of circATRNL1-miR-141-3p/miR-200a-3p-YAP1 axis on Ishikawa cells. Our findings demonstrate that abnormal upregulation of circATRNL1 regulates cell proliferation and motility and promotes EMT process via the miR-141-3p/miR-200a-3p-YAP1 axis in vitro, which could contribute to the progression of endometriosis.

Oestrogen induces epithelial-mesenchymal transition in endometriosis via circ_0004712/miR-148a-3p sponge function

Endometriosis is a common, chronic gynaecologic disease affecting up to 10% of women in their reproductive age and leading to pain and infertility. Oestrogen (E₂)‐induced epithelial‐mesenchymal transition (EMT) process has been considered as a key factor of endometriosis development. Recently, the dysregulated circular RNAs (circRNAs) have been discovered in endometriosis tissues. However, the molecular mechanism of circRNAs on the E₂‐induced EMT process in endometriosis is still unknown. Here, we demonstrated that circ_0004712 up‐regulated by E₂ treatment in endometrial epithelial cells. Knock‐down the expression of circ_0004712 significantly suppressed E₂‐induced cell migration activity. Meanwhile, we identified miR‐148a‐3p as a potential target miRNA of circ_0004712. Inhibited the expression of miR‐148a‐3p could recovered the effect of circ_0004712 knock‐down in E₂‐treated endometrial epithelial. Furthermore, Western blot assay showed that E₂ treatment could increase the expression and activity of β‐catenin, snail and N‐cadherin and reduce the expression of E‐cadherin. The expression and activity of β‐catenin pathway were recovered by circ_0004712 knock‐down or miR‐148a‐3p overexpression. Altogether, the results demonstrate that circ_0004712/miR‐148a‐3p plays an important role in E₂‐induced EMT process in the development of endometriosis, and the molecular mechanism may be associated with the β‐catenin pathway. This work highlighted the importance of circRNAs in the development of endometriosis and provide a new biomarker for diagnosis and therapies.

Epithelial-Mesenchymal Transition in Endometriosis-When Does It Happen?

Epithelial-mesenchymal transition (EMT) is an important process of cell remodeling characterized by the gradual loss of the epithelial phenotype and progressive gain of a mesenchymal phenotype. EMT is not an all-or-nothing process, but instead a transition of epithelial to mesenchymal cells with intermediate cell states. Recently, EMT was described in endometriosis, and many EMT-specific pathways like Twist, Snail, Slug, Zinc finger E-box-binding homeobox 1/2 (ZEB1/2), E/N-cadherin, keratins, and claudins are involved. However, as pointed out in this review, a comparison of the eutopic endometrium of women with and without endometriosis yielded only subtle changes of these EMT markers. Furthermore, only very few alterations in cell-cell contacts could be found but without changes in the epithelial phenotype. This suggests only a partial EMT which is not a prerequisite for the detachment of endometrial cells and, thus, not critical for the first step(s) in the pathogenesis of endometriosis. In contrast, the majority of changes in the EMT-related marker expression were found in the ectopic endometrium, especially in the three endometriotic entities, ovarian, peritoneal, and deep infiltrating endometriosis (DIE), compared with the eutopic endometrium. In this review, we examine the most important EMT pathways described in endometriosis and propose that partial EMT might result from the interaction of endometrial implants with their surrounding microenvironment.

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.

Bioinformatic analysis reveals the importance of epithelial-mesenchymal transition in the development of endometriosis

Background: Endometriosis is a frequently occurring disease in women, which seriously affects their quality of life. However, its etiology and pathogenesis are still unclear. Methods: To identify key genes/pathways involved in the pathogenesis of endometriosis, we recruited 3 raw microarray datasets (GSE11691, GSE7305, and GSE12768) from Gene Expression Omnibus database (GEO), which contain endometriosis tissues and normal endometrial tissues. We then performed in-depth bioinformatic analysis to determine differentially expressed genes (DEGs), followed by gene ontology (GO), Hallmark pathway enrichment and protein-protein interaction (PPI) network analysis. The findings were further validated by immunohistochemistry (IHC) staining in endometrial tissues from endometriosis or control patients. Results: We identified 186 DEGs, of which 118 were up-regulated and 68 were down-regulated. The most enriched DEGs in GO functional analysis were mainly associated with cell adhesion, inflammatory response, and extracellular exosome. We found that epithelial-mesenchymal transition (EMT) ranked first in the Hallmark pathway enrichment. EMT may potentially be induced by inflammatory cytokines such as CXCL12. IHC confirmed the down-regulation of E-cadherin (CDH1) and up-regulation of CXCL12 in endometriosis tissues. Conclusions: Utilizing bioinformatics and patient samples, we provide evidence of EMT in endometriosis. Elucidating the role of EMT will improve the understanding of the molecular mechanisms involved in the development of endometriosis.

Platelets induce endothelial-mesenchymal transition and subsequent fibrogenesis in endometriosis

RESEARCH QUESTION

Do endometriotic lesions undergo endothelial-mesenchymal transition (EndoMT)?

DESIGN

Lesion samples from 30 patients with ovarian endometriomas and deep endometriosis, and control endometrial tissue samples from 30 women without endometriosis, were analysed. In-vitro experimentation using the human umbilical vein endothelial cell (HUVEC) line were conducted. Immunofluorescence staining and immunohistochemistry analysis using antibodies against endothelial cell and mesenchymal cell markers were conducted. The HUVEC cells were co-cultured with activated platelets or control medium with and without neutralization of TGF-β1 PDGFR, or both. Their morphology, proliferation and expression levels of genes and proteins known to be involved in EndoMT were evaluated, along with their migratory and invasive propensity, contractility and collagen production capability.

RESULTS

The proportion of CD31 and FSP-1 dual-positive cells in FSP-1+ fibroblasts was 74.7% (±5.4%) in ovarian endometrioma lesions, significantly higher than that in deep endometriosis lesions (26.8% ± 26.0%; P = 5.7 × 10^-5), and was zero in normal endometrium. The extent of lesional fibrosis correlated positively with staining levels of the lesional mesenchymal markers FSP-1 and α-SMA (r = 0.91; P < 2.2 × 10^-16, r = 0.81; P = 5.8 × 10^-15, respectively). Human endothelial cells co-cultured with activated platelets acquire a morphology suggestive of EndoMT, concomitant with increased proliferation, loss of CD31 but marked increase in expression of mesenchymal markers. Morphological and gene and protein expression changes are accompanied by functional differentiation reflected by increased migratory and invasive capacity, contractility and collagen production. Neutralization of TGF-β1 and PDGFR signalling abolished platelet-induced EndoMT in human endothelial cells.

CONCLUSIONS

Multiple sources of myofibroblasts exist in endometriotic lesions, and implicates platelets, EndoMT, or both, as potential therapeutic targets for treating endometriosis.

The Pathogenesis of Adenomyosis vis-à-vis Endometriosis

Adenomyosis is used to be called endometriosis interna, and deep endometriosis is now called adenomyosis externa. Thus, there is a question as to whether adenomyosis is simply endometriosis of the uterus, either from the perspective of pathogenesis or pathophysiology. In this manuscript, a comprehensive review was performed with a literature search using PubMed for all publications in English, related to adenomyosis and endometriosis, from inception to June 20, 2019. In addition, two prevailing theories, i.e., invagination—based on tissue injury and repair (TIAR) hypothesis—and metaplasia, on adenomyosis pathogenesis, are briefly overviewed and then critically scrutinized. Both theories have apparent limitations, i.e., difficulty in falsification, explaining existing data, and making useful predictions. Based on the current understanding of wound healing, a new hypothesis, called endometrial-myometrial interface disruption (EMID), is proposed to account for adenomyosis resulting from iatrogenic trauma to EMI. The EMID hypothesis not only highlights the more salient feature, i.e., hypoxia, at the wounding site, but also incorporates epithelial mesenchymal transition, recruitment of bone-marrow-derived stem cells, and enhanced survival and dissemination of endometrial cells dispersed and displaced due to iatrogenic procedures. More importantly, the EMID hypothesis predicts that the risk of adenomyosis can be reduced if certain perioperative interventions are performed. Consequently, from a pathogenic standpoint, adenomyosis is not simply endometriosis of the uterus, and, as such, may call for interventional procedures that are somewhat different from those for endometriosis to achieve the best results.

E2 -mediated EMT by activation of β-catenin/Snail signalling during the development of ovarian endometriosis

Endometriosis is an oestrogen-dependent disease, and epithelial-mesenchymal transition (EMT) is involved in the process of endometriosis. Whether oestrogen could induce EMT in endometriosis remains largely unknown. Here, we reported that up-regulated expression of EMT markers in ovarian chocolate cyst is accompanied by high expression 17β-hydroxysteroid dehydrogenase 1 (17β-HSD1), and exposure of primary human endometrial epithelial cells to oestradiol conditions could promote EMT occurrence and activate both β-catenin and Snail signalling. Furthermore, we found nuclear β-catenin and Snail expression was closely linked in ovarian endometriosis, and β-catenin knockdown abrogated oestrogen-induced Snail mediated EMT in vitro. This is due to that β-catenin/ TCF-3 could bind to Snail promoter and activate its transcription. These results suggested that β-catenin signalling functions as the Snail activator and plays a critical role in oestradiol-induced EMT in endometriosis.

Genomic Function of Estrogen Receptor β in Endometriosis

Estrogen receptor (ER) β plays a critical role in endometriosis progression because cytoplasmic ERβ stimulates proinflammatory signaling in ectopic lesions and prevents apoptosis to promote their survival. However, the role of "nuclear ERβ" in endometriosis progression is not known. This critical knowledge gap obscures our understanding of the full molecular etiology of ERβ-mediated endometriosis progression. To fill this void, we generated an ERβ-regulated transcriptome and ERβ cistrome in ectopic lesions and the eutopic endometrium of mice with endometriosis by using a new endometrium-specific FLAG-tagged human ERβ overexpression mouse model. The integration of these omics data sets revealed that ERβ stimulated the proliferation activities of ectopic lesions and the eutopic endometrium by directly upregulating MYC and E2 transcription factor target genes and genes associated with the G2/M transition. Additionally, ERβ stimulated gene expression associated with TNFα/nuclear factor κB (NF-κB) signaling, epithelial-mesenchymal transition, reactive oxygen species signaling, IL-6/Janus kinase (JAK)/signal transducer and activator of transcription (STAT)3 signaling, and hypoxia signaling and suppressed IFNα signaling in ectopic lesions to enhance endometriosis progression. ERβ also stimulated gene expression associated with the unfolded protein response and IL-6/JAK/STAT3 inhibitory signaling and suppressed TNFα/NF-κB signaling in the eutopic endometrium to cause endometriosis-associated endometrial dysfunction. Therefore, nuclear ERβ-regulated gene networks provide critical clues to understand the molecular etiology and complexity of endometriosis and endometriosis-associated endometrial dysfunction.

Expression of vascular endothelial growth factor A isoforms is dysregulated in women with endometriosis

Angiogenesis is a critical step in the development of ectopic lesions during endometriosis. Although total vascular endothelial growth factor (VEGF) A is elevated in the peritoneal fluid of women with endometriosis, there are contradictory reports on how levels of total endometrial VEGFA are altered in this disease. Furthermore, limited research is available on different VEGFA isoforms in women with endometriosis. Thus, the aim of the present study was to analyse levels of various VEGFA isoforms in women with and without endometriosis at different stages of the menstrual cycle. Quantitative polymerase chain reaction analysis showed that total VEGFA was highest during menstruation in endometriosis compared with controls (P=0.0373). VEGF121 and VEGF189 were similarly highest during menstruation in endometriosis compared with controls (P=0.0165 and 0.0154 respectively). The present study is also the first to identify the natural expression of VEGF111 in human tissue, which is also highest during menstruation in endometriosis (P=0.0464). This discovery of the natural production of VEGF111 in human endometrium, as well as the upregulation of VEGFA isoforms during menstruation in endometriosis, may shed further light on the development and progression of the disease, and improve our understanding of the regulation of endometrial angiogenesis.

Inhibition of formin like 2 promotes the transition of ectopic endometrial stromal cells to epithelial cells in adenomyosis through a MET-like process

EMT (Epithelial-Mesenchymal Transition) is one of the factors in the pathogenesis of adenomyosis. FMNL2 induced invasion of cancer cell through promoting EMT, but it is unclear the role of FMNL2 in the adenomyosis. By IHC staining, we found the expression level of FMNL2 was significantly higher in the ectopic endometrial stromal cells from women with adenomyosis when compared with normal endometrial stromal cells. Knockdown of FMNL2 inhibited the invasion and migration of ectopic endometrial stromal cells and promoted the protein levels of E-cadherin and Vimentin. Meanwhile, inhibition of FMNL2 could induce the cell membrane localization of E-cadherin. Our findings reveal that the aberrant activation of FMNL2 promotes the pathogenesis of adenomyosis through inducing the EMT process. On the contrary, inhibition of FMNL2 promotes the transition of ectopic endometrial stromal cells to epithelial cells in adenomyosis through a MET-like process.

SLUG/HIF1-α/miR-221 regulatory circuit in endometrial cancer

BACKGROUND AND PURPOSE

The pathogenesis of endometrial cancer (EC) involves many regulatory pathways including transcriptional regulatory networks supported by transcription factors and microRNAs only in part known. The aim of this retrospective study was to explore the possible correlation in the EC microenvironment between master regulators of complex phenomena such as steroid responsiveness through estrogen receptor alpha (ERα) and progesterone receptor (PR), epithelial-to-mesenchymal transition (supported by SLUG transcription factor), hypoxia (with hypoxia inducible factor-1 alpha, HIF-1α), and obesity that has been recognized as a EC risk factor.

METHODS

Formalin-Fixed Paraffin-Embedded (FFPE) blocks from University of Ferrara Pathology Archive were used and allocated into 2 groups according to their immunohistochemical positivity to ERα and PR, distinguishing the samples with a more benign prognosis (ERα⁺/PR⁺) from those with a poorer prognosis (ERα^-/PR^-). Immunohistochemistry for HIF1-α and SLUG was also performed. Body mass index (BMI) was registered at the time of diagnosis: patients with BMI ≥ 30 kg/m² were defined obese (OB). Total RNA was isolated for miR-221 analysis.

RESULTS

We showed a comparable percentage of HIF1-α and SLUG positive samples in the ERα⁺/PR⁺ and ERα^-/PR^- groups. However, the obesity factor impacted more in the ERα⁺/PR⁺ group since the ratio between OB and non-obese (NOB) patients with high expression of HIF1-α and SLUG was higher in ERα⁺/PR⁺ than in the ERα^-/PR^- group. miR-221 levels were significantly higher in the OB than NOB patients, and, also in this case, obesity impacted more in the ERα⁺/PR⁺ group.

CONCLUSIONS

A molecular circuit of mutual regulation between ERα, PR, HIF1-α, SLUG and miR-221 is feasible in the EC and was firstly suggested by our research. In this interplay miR-221 seems to be in a nodal point of the regulatory system that is particularly strengthened by the metabolic changes in obesity.

Circular RNA expression profiles and bioinformatics analysis in ovarian endometriosis

Background

Circular RNAs (circRNAs) with miRNA response elements (MREs) could function as competing endogenous RNA (ceRNA) in regulating gene expression, thus playing vital roles in pathogenesis and progression of many diseases. However, the function of circRNAs in endometriosis remains unknown. This study was carried to profile the expression patterns of circRNAs in ovarian endometriosis.

Methods

High throughput RNA‐Seq was performed in six paired ectopic and eutopic endometrium tissues (ecEM vs. euEM), followed by quantitative real‐time polymerase chain reaction (qRT‐PCR) in 30 paired samples. Through bioinformatics prediction, we constructed a circRNA‐miRNA ‐mRNA network and elucidated circRNAs functions by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses.

Results

A total of 146 upregulated and 148 downregulated circRNAs were identified, binding with 2,495 MREs. The qRT‐PCR validation results of four upregulated circRNAs matched the RNA‐Seq data. The ceRNA network included 48 miRNAs and 296 mRNAs. Functional analysis revealed several important pathways such as MAPK signaling pathway, and PI3K‐AKT signaling pathway, which might be associated with the pathogenesis and development of endometriosis.

Conclusion

Our data suggested that circRNAs are differentially expressed in endometriosis, which might be candidate factors for pathogenesis of this disease and be considered as promising therapeutic targets in the future.

Hypoxia-Induced Epithelial-To-Mesenchymal Transition Mediates Fibroblast Abnormalities via ERK Activation in Cutaneous Wound Healing

Previous studies described the involvement of extracellular signal-related kinase (ERK) in systemic fibrotic diseases, but the role of ERK in cutaneous scarring is unknown. Although hypoxia drives tissue fibrosis by activating hypoxia-inducible factor-1α (HIF-1α), the specific roles of hypoxia and associated ERK phosphorylation in abnormal fibroblast activity during cutaneous scarring are unclear. Here, we investigated whether pathologic myofibroblast-like keloid fibroblast activity is promoted by hypoxia-induced epithelial-mesenchymal transition mediated by ERK activation. ERK phosphorylation was significantly increased in keloid tissue and fibroblasts. Human dermal fibroblasts cultured under hypoxia (1% O₂) expressed phosphorylated ERK and exhibited activation of p38 mitogen-activated protein kinase signaling. Hypoxic human dermal fibroblasts showed increased protein and mRNA levels of epithelial-mesenchymal transition markers. Furthermore, administration of an ERK inhibitor (SCH772984) reduced the hypoxia-induced elevation of collagen type I levels in human dermal fibroblasts. Therefore, ERK may be a promising therapeutic target in profibrogenic diseases.