CircFOXO3 mediates hypoxia-induced autophagy of endometrial stromal cells in endometriosis.

Endometriosis is a benign gynecological disease that shares some common features of malignancy. Autophagy plays vital roles in endometriosis and influences endometrial cell metastasis, and hypoxia was identified as the initiator of this pathological process through hypoxia inducible factor 1 alpha (HIF-1α). A newly discovered circular RNA FOXO3 (circFOXO3) is critical in cell autophagy, migration, and invasion of various diseases and is reported to be related to hypoxia, although its role in endometriosis remains to be elucidated up to now. In this study, a lower circFOXO3 expression in ectopic endometrium was investigated. Furthermore, we verified that circFOXO3 could regulate autophagy by downregulating the level of p53 protein to mediate the migration and invasion of human endometrial stromal cells (T HESCs). Additionally, the effects of HIF-1α on circFOXO3 and autophagy were examined in T HESCs. Notably, overexpression of HIF-1α could induce autophagy and inhibit circFOXO3 expression, whereas overexpressing of circFOXO3 under hypoxia significantly inhibited hypoxia-induced autophagy. Mechanistically, the direct combination between HIF-1α and HIF-1α-binding site on adenosine deaminase 1 acting on RNA (ADAR1) promoter increased the level of ADAR1 protein, which bind directly with circFOXO3 pre-mRNA to block the cyclization of circFOXO3. All these results support that hypoxia-mediated ADAR1 elevation inhibited the expression of circFOXO3, and then autophagy was induced upon loss of circFOXO3 via inhibition of p53 degradation, participating in the development of endometriosis.

Transcriptome-wide N6-methyladenosine (m6A) methylation profiling of long non-coding RNAs in ovarian endometriosis.

N6-methyladenosine (m6A) methylation is the most prevalent internal epigenetic posttranscriptional mechanism for regulating mammalian RNA. Despite recent advances in determining the biological functions of m6A methylation, its association with the pathology of ovarian endometriosis remains uncertain. Herein, we performed m6A transcriptome-wide profiling to identify key lncRNAs with m6A modification involved in ovarian endometriosis development by bioinformatics analysis. We found the total m6A level was lower in ovarian endometriosis than in normal endometrium samples, with 9663 m6A peaks associated with 8989 lncRNAs detected in ovarian endometriosis and 9902 m6A peaks associated with 9210 lncRNAs detected in normal endometrium samples. These m6A peaks were primarily enriched within AAACU motifs. Functional enrichment analysis indicated that pathways involving the regulation of adhesion and development were significantly enriched in these differentially methylated lncRNAs. The regulatory relationships among lncRNAs, microRNAs (miRNAs), and mRNAs were identified by competing endogenous RNA (ceRNA) analysis and determination of the network regulating lncRNA-mRNA expression. Several specific lncRNA, including LINC00665, LINC00937, FZD10-AS1, DIO3OS and GATA2-AS1 which were differently expressed and modified by m6A, were validated using qRT-PCR and its interaction with infiltrating immune cells was explored. Furthermore, we found LncRNA DIO3OS promotes the invasion and migration of Human endometrial stromal cells (THESCs) and ALKBH5 regulates the expression of the lncRNA DIO3OS through m6A modification in vitro. Our study firstly revealed the transcriptome-wide map of m6A modification in lncRNAs of ovarian endometriosis. These findings may enable the determination of the underlying mechanism governing the pathogenesis of ovarian endometriosis and provide theoretical basis for further deeper research on the role of m6A in the development of ovarian endometriosis.

METTL3-dependent m6A modification facilitates decreased endometrial decidualization via attenuation MET in endometriosis.

Mesenchymal-epithelial transition (MET)-mediated endometrial decidualization is pivotal for achieving endometrial receptivity and successful pregnancy. We observed blockade of MET in the eutopic secretory endometrium of patients with endometriosis, but the underlying mechanism is unknown. In this study, real-time PCR was used to detect PRL and IGFBP1 expression, whereas western blotting was used to detect the expression of MET markers and METTL3. Phalloidin staining was used to identify changes in cell morphology. M6A levels were quantified using a colorimetric method and m6A dot blots, and functional analysis was performed using spheroid adhesion assays. We first found that increased E-cadherin expression was accompanied by decreased Vimentin and Slug expression in the eutopic secretory endometrium of individuals with endometriosis. We also detected a significant increase in both the m6A level and the expression of the related methyltransferase METTL3. Finally, METTL3 expression was negatively correlated with PRL, IGFBP1and MET markers expression. Collectively, our findings suggest that METTL3 mediates m6A modification, thereby inhibiting MET formation within the eutopic secretory endometrium of patients with endometriosis. Increased METTL3-mediated m6A modification plays a crucial role in attenuating MET formation and decidualization impairment in endometrial stromal cells, ultimately contributing to compromised endometrial receptivity in individuals with endometriosis. These insights could lead to the identification of potential therapeutic targets for improving both endometrial receptivity and pregnancy rate among individuals affected by endometriosis.

A novel mechanism regulating pyroptosis-induced fibrosis in endometriosis via lnc-MALAT1/miR-141-3p/NLRP3 pathway†.

Endometriosis is a chronic inflammatory disease distinguished by ectopic endometrium and fibrosis. NLRP3 inflammasome and pyroptosis are present in endometriosis. Aberrant increase of Long noncoding (Lnc)-metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) plays a vital role in endometriosis. However, the relationship between lnc-MALAT1, pyroptosis, and fibrosis is not completely known. In the present study, we found that the pyroptosis levels in ectopic endometrium of patients with endometriosis were significantly increased, consistent with fibrosis levels. Lipopolysaccharide (LPS) + ATP could induce pyroptosis of primary endometrial stromal cells (ESCs), thereby releasing interleukin (IL)-1ß and stimulating transforming growth factor (TGF)-ß1-mediated fibrosis. NLRP3 inhibitor MCC950 had the same effect as TGF-ß1 inhibitor SB-431542 in suppressing the fibrosis-inducing effect of LPS + ATP in vivo and in vitro. The abnormal increase of lnc-MALAT1 in ectopic endometrium was connected with NLRP3-mediated pyroptosis and fibrosis. Leveraging bioinformatic prediction and luciferase assays combined with western blotting and quantitative reverse transcriptase-polymerase chain reaction, we validated that lnc-MALAT1 sponges miR-141-3p to promote NLRP3 expression. Silencing lnc-MALAT1 in HESCs ameliorated NLRP3-mediated pyroptosis and IL-1ß release, thereby relieving TGF-ß1-mediated fibrosis. Consequently, our findings suggest that lnc-MALAT1 is critical for NLRP3-induced pyroptosis and fibrosis in endometriosis through sponging miR-141-3p, which may indicate a new therapeutic target of endometriosis treatment.

METTL3-regulated m6A modification impairs the decidualization of endometrial stromal cells by regulating YTHDF2-mediated degradation of FOXO1 mRNA in endometriosis-related infertility.

BACKGROUND: Endometriosis-related infertility is a common worldwide reproductive health concern. Despite ongoing research, the causes of infertility remain unclear. Evidence suggests that epigenetic regulation is crucial in reproduction. However, the role of N6-methyladenosine (m6A) modification of RNA in endometriosis-related infertility requires further investigation. METHODS: We examined the expression of m6A and methyltransferase-like 3 (METTL3) in endometrial samples taken from normal fertile women in the proliferative phase (the NP group) or the mid-secretory phase (the NS group) or from women with endometriosis-related infertility at the mid-secretory phase (the ES group). We treated primary endometrial stromal cells (ESCs) with medroxyprogesterone acetate and 8-Bromo-cyclic adenosine monophosphate for in vitro decidualization and detected the expression of m6A, METTL3, and decidual markers. We analyzed the expression of m6A, METTL3, and forkhead box O1 (FOXO1) in ESCs from normal fertile women (the ND group) or women with endometriosis-related infertility (the ED group). We also assessed the expression of m6A, METTL3, and decidual markers, as well as the embryo adhesion rate, upon METTL3 overexpression or knockdown. Additionally, we investigated the role of METTL3 in embryo implantation in vivo by applying mice with endometriosis. Furthermore, we performed RNA stability assays, RNA immunoprecipitation (RIP), and methylated RIP assays to explore the mechanisms underlying the regulation of FOXO1 by METTL3-mediated m6A. RESULTS: The expression of m6A and METTL3 was reduced only in the NS group; the NP and ES groups demonstrated increased m6A and METTL3 levels. m6A and METTL3 levels decreased in ESCs with prolonged decidual treatment. Compared to the ND group, m6A and METTL3 levels in the ED group increased after decidual treatment, whereas the expression of FOXO1 decreased. METTL3 overexpression suppressed the expression of decidual markers and embryo implantation in vitro; METTL3 knockdown exhibited the opposite effect. Inhibition of METTL3 promoted embryo implantation in vivo. Furthermore, we observed that METTL3-mediated m6A regulated the degradation of FOXO1 mRNA through YTHDF2, a m6A binding protein. CONCLUSIONS: METTL3-regulated m6A promotes YTHDF2-mediated decay of FOXO1 mRNA, thereby affecting cellular decidualization and embryo implantation. These findings provide novel insights into the development of therapies for women with endometriosis-related infertility.

Low dose of liraglutide combined with metformin leads to a significant weight loss in Chinese Han women with polycystic ovary syndrome: a retrospective study.

BACKGROUND: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder with complex pathophysiological mechanism. It is reported that even a modest weight loss of 5-10% substantially may improve the reproductive and metabolic profile. This study aims to assess the efficacy of the low dose of liraglutide (0.6 mg QD) combined with metformin (0.85 mg BID) in weight loss in Chinese Han women with PCOS. METHODS: We included clinical data of 102 obese/overweight (≥18 years, body mass index ≥28 kg/m2 or ≥24 kg/m2) women who were diagnosed with PCOS from October 2016 to March 2018 in Wuhan Union Hospital initially. They were treated with dinae-35, low dose of liraglutide (0.6 mg QD) and metformin (0.85 mg BID) for 12 weeks. The demographic and clinical data were retrieved retrospectively, and weight loss was the main outcome measure. Student's paired t-test and Wilcoxon rank sum test were used to compare the differences before and after therapy, p < 0.05 was considered statistically significant. RESULTS: Participants(n = 102)had lost a mean of 7.20 ± 3.42 kg of body weight (95%CI: 6.55-7.86, p < 0.001), and the mean reduction of BMI was 2.87 ± 1.36 kg/m2 (95%CI: 0.02-0.27, p < 0.001). A total of 88.24% of participants lost more than 5% of their body weight. CONCLUSION: The combination of low dose of liraglutide and metformin was associated with significant reduction of body weight in Chinese Han women with PCOS. Additionally, a larger randomized double-blind multicenter controlled clinical trial is needed to confirm that. TRIAL REGISTRATION: The study was registered on http://www.chictr.org.cn as ChiCTR1900024384.

Estrogen receptor α mediated M1/M2 macrophages polarization plays a critical role in NASH of female mice.

Owing to lacking protective effect of estrogen, OVX mice have higher risk of non-alcoholic fatty liver disease compared with normal female mice, when fed with high fat diet. Our study was to explore how estrogen protect against nonalcoholic steatohepatitis in female mice. We found that, lacking estrogen, M1 macrphages was activated and promoted steatohepatitis in obese OVX mice. And, ERα was responsible for estrogen to inhibit M1 macrphages activation and steatohepatitis. ERα knockdown aggravated M1 macrophages infiltration by transcriptionally upregulated its CCR2 expression. CCR2 antagonist effectively improved nonalcoholic steatohepatitis, ER stress and insulin resistance in ERα knockdown obese female mice. These results demonstrated ERα mediated M1 macrophages activation played a key role in nonalcoholic steatohepatitis.

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

N 6-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), whereas 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 and 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.

Oestrogen receptors and hypoxia inducible factor 1 alpha expression in abdominal wall endometriosis.

RESEARCH QUESTION: What are the protein levels and localization of oestrogen receptors (including ERa, ERb and G protein-coupled oestrogen receptor [GPER]) and hypoxia-inducible factor-1alpha (HIF-1a) in normal control endometrium (COEM) and ectopic endometrium from abdominal wall endometriosis (AWE). DESIGN: AWE (n = 20) were obtained during surgery; COEM (n = 40) were collected by curettage. All tissues were obtained during the proliferative or secretory phase. Formalin-fixed paraffin-embedded tissues were used for immunohistochemical study for oestrogen receptors and HIF-1a proteins. RESULT(S): The expression of oestrogen receptors and HIF-1a in AWE differed from that in the corresponding menstrual cycle phase of COEM. Compared with COEM, ERa and HIF-1a were decreased whereas ERb and GPER were increased in AWE. The greatest difference was in GPER, with increased protein expression in both the cytoplasm and nucleus of endometrial epithelial and stromal cells, as well as a distinct change in localization from cytoplasmic expression to nuclear and cytoplasmic expression, compared with COEM. CONCLUSIONS: Our data suggest that the expression changes of oestrogen receptors and HIF-1a, especially GPER, are associated with AWE, which may provide new clues to understanding the cause of endometriosis.

Long non-coding RNA MALAT1 mediates hypoxia-induced pro-survival autophagy of endometrial stromal cells in endometriosis.

Endometriosis is a common gynecological disease characterized by diminished apoptosis, sustained ectopic survival of dysfunctional endometrial cells. Hypoxia has been implicated as a crucial microenvironmental factor that contributes to endometriosis. It has been reported that long non-coding RNA MALAT1 (lncRNA-MALAT1) highly expressed in endometriosis and up-regulated by hypoxia. Hypoxia may also induce autophagy, which might act as cell protective mechanism. However, the relationship between lncRNA-MALAT1 and autophagy under hypoxia conditions in endometriosis remains unknown. In the present study, we found that both lncRNA-MALAT1 and autophagy level were up-regulated in ectopic endometrium from patients with endometriosis, and its expression level correlates positively with that of hypoxia-inducible factor-1α (HIF-1α). In cultured human endometrial stromal cells, both lncRNA-MALAT1 and autophagy were induced by hypoxia in a time-dependent manner and lncRNA-MALAT1 up-regulation was dependent on HIF-1α signalling. Our analyses also show that knockdown of lncRNA-MALAT1 suppressed hypoxia induced autophagy. Furthermore, inhibiting autophagy with specific inhibitor 3-Methyladenine (3-MA) and Beclin1 siRNA enhanced apoptosis of human endometrial stromal cells under hypoxia condition. Collectively, our findings identify that lncRNA-MALAT1 mediates hypoxia-induced pro-survival autophagy of endometrial stromal cells in endometriosis.

E2 -mediated EMT by activation of ß-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 17ß-hydroxysteroid dehydrogenase 1 (17ß-HSD1), and exposure of primary human endometrial epithelial cells to oestradiol conditions could promote EMT occurrence and activate both ß-catenin and Snail signalling. Furthermore, we found nuclear ß-catenin and Snail expression was closely linked in ovarian endometriosis, and ß-catenin knockdown abrogated oestrogen-induced Snail mediated EMT in vitro. This is due to that ß-catenin/ TCF-3 could bind to Snail promoter and activate its transcription. These results suggested that ß-catenin signalling functions as the Snail activator and plays a critical role in oestradiol-induced EMT in endometriosis.

A functional interaction between Hippo-YAP signalling and SREBPs mediates hepatic steatosis in diabetic mice.

The Hippo pathway is an evolutionarily conserved regulator of organ size and tumorigenesis that negatively regulates cell growth and survival. Whether the Hippo pathway regulates cell metabolism is unknown. Here, we report that in the nucleus of hepatocytes, Yes-associated protein(YAP)-the terminal effector of the Hippo pathway-directly interacts with sterol regulatory element binding proteins (SREBP-1c and SREBP-2) on the promoters of the fatty acid synthase (FAS) and 30-hydroxylmethyl glutaryl coenzyme A reductase (HMGCR), thereby stimulating their transcription and promoting hepatocyte lipogenesis and cholesterol synthesis. In diet-induced diabetic mice, either Lats1 overexpression or YAP knockdown protects against hepatic steatosis and hyperlipidaemia through suppression of the interaction between YAP and SREBP-1c/SREBP-2. These results suggest that YAP is a nuclear co-factor of SREBPs and that the Hippo pathway negatively affects hepatocyte lipogenesis by inhibiting the function of YAP-SREBP complexes.

Estradiol promotes EMT in endometriosis via MALAT1/miR200s sponge function.

Endometriosis is an estrogen-dependent benign gynecological disease that shares some common features of malignancy. Epithelial-mesenchymal transition (EMT) has been recognized as a core mechanism of endometriosis. MALAT1 is widely known as EMT promoter, while miR200 family members (miR200s) are considered as EMT inhibitors. Previous studies have reported that MALAT1 upregulation and miR200s downregulation are observed in endometriosis. MiR200c has been regarded as the strongest member of miR200s to interact with MALAT1. However, whether MALAT1/miR200c regulates EMT remains largely unclear. In this study, the roles of miR200s and MALAT1 in ectopic endometrium were investigated. Additionally, the effects of E2 on EMT and MALAT1/miR200s were examined in both EECs and Ishikawa cells. Notably, E2 could upregulate MALAT1 and downregulate miR200s expression levels and induce EMT in EECs and Ishikawa cells. PHTPP, an ERß antagonist, could reverse the effect of E2. Overexpression of miR200c and knockdown of MALAT1 significantly inhibited E2-mediated EMT, suggesting that both miR200c and MALAT1 are involved in the E2-induced EMT process in endometriosis. In addition, a reciprocal inhibition was found between miR200s and MALAT1. Therefore, the role of MALAT1/miR200c in EMT is influenced by the presence of estrogen during endometriosis development.

Autophagy contributes to hypoxia-induced epithelial to mesenchymal transition of endometrial epithelial cells in endometriosis.

Endometriosis is a benign gynecologic disorder, and presents with malignant characteristics, such as migration and invasion. Hypoxia has been implicated in triggering epithelial-mesenchymal transition (EMT). Hypoxia is also known to induce autophagy. However, the relationship between autophagy and EMT under hypoxia conditions in endometriosis remains unknown. In the present study, we found that the expression of hypoxia-inducible factor-1α (HIF-1α), microtubule associated protein light chain 3 (LC3), and mesenchymal cell marker vimentin was significantly higher in ectopic endometrium from patients with endometriosis, along with decreased expression of epithelial cell marker E-cadherin. After hypoxia treatment, endometrial epithelial cells exhibited enhanced migration and invasion abilities, as well as promoted autophagy and the EMT phenotype. Our analyses also show that HIF-1α was responsible for induction of autophagy. Moreover, inhibition of autophagy by chemical or genetic approaches suppressed hypoxia triggered EMT and reduced cell migration and invasion. Collectively, our findings identify that autophagy is critical for the migration and invasion of endometrial cells through the induction of EMT and indicate that inhibition of autophagy may be a novel useful strategy in the treatment of endometriosis.

Notch activity mediates oestrogen-induced stromal cell invasion in endometriosis.

Oestrogen has been reported to control the invasiveness of endometrial stromal cells in endometriosis. Notch signalling, a master regulator of cell invasion in tumours, is regulated by oestrogen in other diseases and hyperactivated in endometriotic stromal cells. Therefore, we hypothesized that an interaction between Notch signalling and oestrogen may exist in the regulation of endometrial stromal cell invasion, which is essential for the development of endometriosis. Western blot analysis of tissues showed that the expression levels of Notch components (JAG1 and NOTCH1) and Notch activity were markedly higher in ectopic endometria than in their eutopic and normal counterparts. Primary stromal cells obtained from normal endometria cultured with oestrogen presented significant increases in the expression of Notch components and Notch activity, the cytoplasmic and nuclear accumulation of NOTCH1 intracellular domain, the expression of matrix metallopeptidase 9 and vascular endothelial growth factor and cell invasiveness. Knockdown of NOTCH1 markedly alleviated oestrogen-induced matrix metallopeptidase 9 and vascular endothelial growth factor expression and cell invasion. ICI (an oestrogen receptor α antagonist) also blocked these oestrogenic effects. Oestrogen-responsive elements were found in the promoters of NOTCH1 and JAG1. A luciferase reporter analysis revealed that oestrogen regulated the expression of Notch components via oestrogen receptor alpha, which is bound to oestrogen-responsive elements in the JAG1 and NOTCH1 promoters. Collectively, our findings indicate that oestrogen engages in crosstalk with Notch signalling to regulate cell invasion in endometriosis via the activation of oestrogen receptor alpha and the enhancement of Notch activity. Notch signalling blockade may therefore be a novel therapeutic target for endometriosis.

Hypoxia-inducible factor-1α promotes endometrial stromal cells migration and invasion by upregulating autophagy in endometriosis.

Endometriosis is a benign gynecological disease that shares some characteristics with malignancy like migration and invasion. It has been reported that both hypoxia-inducible factor-1α (HIF-1α) and autophagy were upregulated in ectopic endometrium of patients with ovarian endometriosis. However, the crosstalk between HIF-1α and autophagy in the pathogenesis of endometriosis remains to be clarified. Accordingly, we investigated whether autophagy was regulated by HIF-1α, as well as whether the effect of HIF-1α on cell migration and invasion is mediated through autophagy upregulation. Here, we found that ectopic endometrium from patients with endometriosis highly expressed HIF-1α and autophagy-related protein LC3. In cultured human endometrial stromal cells (HESCs), autophagy was induced by hypoxia in a time-dependent manner and autophagy activation was dependent on HIF-1α. In addition, migration and invasion ability of HESCs were enhanced by hypoxia treatment, whereas knockdown of HIF-1α attenuated this effect. Furthermore, inhibiting autophagy with specific inhibitors and Beclin1 siRNA attenuated hypoxia triggered migration and invasion of HESCs. Taken together, these results suggest that HIF-1α promotes HESCs invasion and metastasis by upregulating autophagy. Thus, autophagy may be involved in the pathogenesis of endometriosis and inhibition of autophagy might be a novel therapeutic approach to the treatment of endometriosis.

Intracellular Wnt/Beta-Catenin Signaling Underlying 17beta-Estradiol-Induced Matrix Metalloproteinase 9 Expression in Human Endometriosis.

Extracellular matrix remodeling is necessary for ectopic endometrium implantation. Many studies have shown an increased expression of matrix metalloproteinase 9 (MMP9) in the ectopic endometrium of endometriosis. However, the signaling pathways and cellular effects related to this process remain incompletely elucidated. The objective of our study was to investigate the association between MMP9 and the Wnt signaling pathway under the regulation of 17beta-estradiol (E2) in endometrial stromal cells. We found that MMP9 was elevated in tissues from women with endometriosis compared with normal women. Furthermore, MMP9 and beta-catenin increased concurrently in a time- and dose-dependent manner after E2 treatment. To clarify the relationship between MMP9 and beta-catenin, we performed luciferase promoter reporter and chromatin immunoprecipitation assays. A beta-catenin/TCF3/LEF1 complex bound to a specific site on the MMP9 promoter that promoted MMP9 gene and protein expression. The promotion of MMP9 by the Wnt signaling pathway under the regulation of E2 may contribute to the pathophysiology of this disease.

17 ß-Estradiol promotes vascular endothelial growth factor expression via the Wnt/ß-catenin pathway during the pathogenesis of endometriosis.

STUDY HYPOTHESIS: Do estrogen and Wnt/ß-catenin signaling promote vascular endothelial growth factor (VEGF) expression in endometriosis and how? STUDY FINDING: 17ß-Estradiol (E2)-drives ß-catenin triggered up-regulation of VEGF in effector human primary endometrial stromal cells (ESCs) and thus enhances their ability to establish a new blood supply to the human exfoliated endometrium. WHAT IS KNOWN ALREADY: Implantation and survival of exfoliated endometrium is crucially dependent on neovascularization and Wnt/ß-catenin signaling plays an important role in stimulating angiogenesis. STUDY DESIGN, SAMPLES/MATERIALS, METHODS: Expression levels of VEGF mRNA, estrogen receptor α (ERα) and ß-catenin protein were measured in ovarian endometriosis, eutopic endometrium of endometriosis patients and normal endometrium with real-time RT-PCR and western blot. ESCs were treated with 10 nM E2 for different times in order to evaluate the effect of E2 on ERα, ß-catenin and VEGF expression in these cells. Human endometrial stromal cells (T HESCs) were cultured for transfection with expression vectors and siRNA constructs and used in chromatin immunoprecipitation (ChIP) and luciferase assays, which were conducted to clarify the regulation mechanism of E2 on VEGF. MAIN RESULTS AND THE ROLE OF CHANCE: VEGF, ERα and ß-catenin expression was increased in endometriotic lesions compared with normal endometrium. E2 could promote ERα, ß-catenin and VEGF expression in ESCs. ChIP and luciferase assays revealed that E2 up-regulated ß-catenin expression by binding to the estrogen response element site on the ß-catenin promoter. ß-Catenin stabilization could activate Wnt/ß-catenin signaling, which has a direct transcriptional effect on VEGF gene expression. LIMITATIONS, REASONS FOR CAUTION: Endometriotic lesions were all from ovarian endometriosis and may differ from other type of endometriosis. WIDER IMPLICATIONS OF THE FINDINGS: These promising results improve the body of knowledge on endometriosis pathogenesis and could open up new therapeutic strategies for the treatment of endometriosis. STUDY FUNDING AND COMPETING INTERESTS: This project was supported by the National Natural Science Foundation of China (grant no. 81170545 Y.L. and 81471439 Y.L.). None of the authors has any conflicting interests to declare.

Hypoxia-inducible factor 1α-induced epithelial-mesenchymal transition of endometrial epithelial cells may contribute to the development of endometriosis.

STUDY QUESTION: How does hypoxia promote growth of lesions in the development of endometriosis? SUMMARY ANSWER: Hypoxia induces the epithelial-mesenchymal transition (EMT) of endometrial cells, resulting in changes in cellular characteristics, which may be a prerequisite for the establishment of endometriotic lesions. WHAT IS KNOWN ALREADY: Up-regulated hypoxia-inducible factor 1α (HIF-1α) has recently been found in ectopic endometrial lesions. There is increasing evidence that EMT, in which epithelial cells acquire mesenchymal and migratory properties, may also play a role in the establishment of the disease. EMT induced by HIF-1α has been reported to play a role in the development of many tumor types. STUDY DESIGN, SIZE, DURATION: We investigated expression changes of N-cadherin, E-cadherin, ß-catenin, HIF-1α and vimentin using immunohistochemistry in normal, eutopic and ectopic endometria. Endometrial tissues from 96 additional females without related pathology were collected, and these tissues were subjected to subsequent primary cell culture for further experiments. PARTICIPANTS/MATERIALS, SETTING, METHODS: The expression of N-cadherin, E-cadherin, ß-catenin, HIF-1α and vimentin in 20 normal, 21 eutopic and 21 ectopic endometrial samples was assessed by immunohistochemistry. Human primary endometrial epithelial cells were isolated from 96 normal endometrial tissues. Times for hypoxia treatment for western blot analysis were 1, 2, 4 and 8 h, for transwell experiments was 48 h. Ishikawa cells were used instead of primary endometrial epithelial cells for transfection and part of the transwell experiments. The impact of hypoxia on invasion was evaluated by transwell assays. Overexpression and inhibition of HIF-1α were achieved by transfection of pG/CMV/HIF-1α/IRES/EGFP and MCS-shHIF-1α-EGFP-IRES plasmids separately. The effect of hypoxia, overexpression and knockdown of HIF-1α on hypoxia-induced changes of EMT markers and ß-catenin were analyzed by western blot and reverse transcriptase polymerase chain reaction (RT-PCR). MAIN RESULTS AND THE ROLE OF CHANCE: Overexpression of HIF-1α and changes associated with EMT were observed in normal, eutopic and ectopic endometrial tissues. Primary cultured human endometrial epithelial cells responded to hypoxia with classic EMT changes (fibroblastoid phenotype, increased expression of snail family zinc finger 1, ß-catenin and mesenchymal markers, and decreased expression of E-cadherin) and increased invasiveness. The decreased invasiveness of Ishikawa cells by knockdown of HIF-1α was observed under hypoxic conditions. While up-regulation of HIF-1α induced changes characteristic of EMT, down-regulation of HIF-1α had the opposite effect. Statistical significance was defined as P < 0.05. LIMITATIONS, REASONS FOR CAUTION: A weakness of this study is the relatively small sample size for immunohistochemistry. Ishikawa cells were used instead of primary endometrial epithelial cells for transfection and part of the transwell experiments. WIDER IMPLICATIONS OF THE FINDINGS: Hypoxia-stabilized HIF-1α may play an important role in the invasion of endometrial cells in ectopic endometrial lesions, and it may induce EMT in the development of endometriosis. HIF-1α may be a new and important target for the endometriosis treatment. STUDY FUNDING/COMPETING INTERESTS: This study was funded by the National Nature Science Foundation of China (grant number 81170545 and 81471439). The authors declare no competing interests.

Estradiol promotes cells invasion by activating ß-catenin signaling pathway in endometriosis.

Endometriosis is an estrogen-dependent disease that involves the adhesion, invasion, and angiogenesis of endometrial tissues outside of the uterine cavity. We hypothesized that a link exists between estrogen and beta-catenin (ß-catenin) signaling in the pathogenesis of endometriosis. Human endometrial stromal cells (HESCs) were separated from eutopic endometrial tissues that were obtained from patients with endometriosis. ß-catenin expression and cells invasiveness ability were up-regulated by 17ß-estradiol (E2) in an estrogen receptor (ESR)-dependent manner, whereas ß-catenin siRNA abrogated this phenomenon. Moreover, co-immunoprecipitation and dual immunofluorescence studies confirmed ESR1, ß-catenin, and lymphoid enhancer factor 1/T cell factor 3 co-localization in the nucleus in HESCs after E2 treatment. To determine the role of ß-catenin signaling in the implantation of ectopic endometrium, we xenotransplanted eutopic endometrium from endometriosis patients into ovariectomized severe combined immunodeficiency mice. The implantation of the endometrium was suppressed by ß-catenin siRNA. Collectively, studies regarding ß-catenin signaling are critical for improving our understanding of the pathogenesis of estrogen-induced endometriosis, which can translate into the development of treatments and therapeutic strategies for endometriosis.