Upregulated Circular RNA hsa_circ_0008433 Regulates Pathogenesis in Endometriosis Via miRNA

circAMN1-Mediated Ferroptosis Regulates the Expulsion of Placenta in Trophoblast Cells

After delivery, the death of trophoblast cells can promote the expulsion of the placenta. Ferroptosis, an iron-dependent programmed cell death, is involved in mammalian development. Circular RNAs are associated with placental development; however, it is unclear whether circular RNAs regulate the expulsion of fetal membranes through ferroptosis. The gene expression profiles in the tail vein blood of Holstein cows with normal and retained placentas were investigated using RNA sequencing and a GSE214588 dataset. circAMN1 and SLC39A8 expression was significantly downregulated in the blood of cows with a retained placenta, whereas miR-205_R-1 expression was significantly upregulated. We validated erastin-induced ferroptosis in trophoblast cells. Transfection with si-circAMN1 and miR-205_R-1 mimic reduced intracellular total iron, Fe2+, and glutathione disulfide levels; increased intracellular glutathione levels and glutathione/glutathione disulfide; and enhanced cell viability in these cells. In contrast, transfection with pcDNA3.1 circAMN1 and an miR-205_R-1 inhibitor promoted ferroptosis. As an miR-205_R-1 sponge, circAMN1 regulated the expression of SLC39A8 to control erastin-induced ferroptosis and regulated the proliferation, invasion, and migration of trophoblast cells. Our findings provide a theoretical basis for studying the mechanism by which programmed cell death regulates fetal membrane expulsion and indicate its potential as a therapeutic target for placenta retention.

CBX7 is involved in the progression of cervical cancer through the ITGβ3/TGFβ1/AKT pathway

The chromobox protein homolog 7 (CBX7) serves a tumor-suppressive role in human malignant neoplasias. The downregulation of CBX7 is associated with the poor prognosis and aggressiveness of various human cancers. However, the biological functions and underlying mechanisms of CBX7 in cervical cancer remain unclear. The present study investigated the role and mechanism of CBX7 in cervical cancer. Lentivirus and siRNA were used to construct cervical cancer cells with stable CBX7 knockdown and SiHa xenograft models. The cell growth, migration, invasion and apoptosis were observed through in vivo and in vitro experiments. The expression levels of CBX7, integrin β3 (ITGβ3), transforming growth factor β1 (TGFβ1), phosphatidylinositol-3-kinase (PI3K), AKT, E-cadherin (E-cad) and vimentin (VIM) were detected by western blot analysis and reverse transcription-quantitative PCR. The correlation between CBX7 and these genes was analyzed. TGFβ1 was also silenced through shRNA in cells with stable CBX7 knockdown to detect its effect on cell growth, invasion and apoptosis, and on pathway-related gene expression. It was revealed that knockdown of CBX7 promoted the proliferation, migration, and invasion of cervical cancer cells, and inhibited apoptosis. In addition, CBX7 knockdown promoted tumor growth in vivo. Correlation analysis demonstrated that CBX7 was negatively correlated with ITGβ3, TGFβ1, PI3K, AKT, phosphorylated AKT and VIM, but positively correlated with E-cad. Moreover, the knockdown of TGFβ1 reversed the promotion of cell proliferation and inhibition of apoptosis induced by CBX7 knockdown and attenuated the increase of ITGβ3, TGFβ1, PI3K, AKT and VIM caused by CBX7 knockdown. In conclusion, the findings of the present study indicated that the downregulation of CBX7 enhances cell migration and invasion while inhibiting cell apoptosis in cervical cancer by modulating the ITGβ3/TGFβ1/AKT signaling pathways.

Molecular Mechanisms of Endometriosis Revealed Using Omics Data

Endometriosis is a gynecological disorder prevalent in women of reproductive age. The primary symptoms include dysmenorrhea, irregular menstruation, and infertility. However, the pathogenesis of endometriosis remains unclear. With the advent of high-throughput technologies, various omics experiments have been conducted to identify genes related to the pathophysiology of endometriosis. This review highlights the molecular mechanisms underlying endometriosis using omics. When genes identified in omics experiments were compared with endometriosis disease genes identified in independent studies, the number of overlapping genes was moderate. However, the characteristics of these genes were found to be equivalent when functional gene set enrichment analysis was performed using gene ontology and biological pathway information. These findings indicate that omics technology provides invaluable information regarding the pathophysiology of endometriosis. Moreover, the functional characteristics revealed using enrichment analysis provide important clues for discovering endometriosis disease genes in future research.

circPLOD2 knockdown suppresses endometriosis progression via the miR-216a-5p/ZEB1 axis

The present study aimed to identify the role of circPLOD2 in endometriosis and its underlying mechanisms. We determined circPLOD2 and miR-216a-5p expression in ectopic endometrial (EC) and eutopic endometrial (EU) samples as well as in endometrial samples from uterine fibroids of ectopic patients (EN) and embryonic stem cells (ESCs) using qRT-PCR. The association between circPLOD2 and miR-216a-5p or miR-216a-5p and zinc finger E-box binding homeobox 1 (ZEB1) expression was analyzed using Starbase, TargetScan, and dual-luciferase reporter gene assays. Cell viability, apoptosis, and migration and invasion were assessed using MTT, flow cytometry, and transwell assays, respectively. In addition, qRT-PCR and western blotting was used to measure circPLOD2, miR-216a-5p, E-cadherin, N-cadherin, and ZEB1 expression. circPLOD2 was upregulated and miR-216a-5p was downregulated in EC samples compared with that in EU samples. Similar trends were observed in ESCs. circPLOD2 interacted and negatively regulated miR-216a-5p expression in EC-ESCs. circPLOD2-siRNA significantly inhibited EC-ESC growth; promoted cellular apoptosis; and inhibited EC-ESC migration, invasion, and epithelial-mesenchymal transition; these effects could be reversed following miR-216a-5p inhibitor transfection. miR-216a-5p directly targeted and negatively regulated ZEB1 expression in EC-ESCs. In conclusion, circPLOD2 promotes the proliferation, migration, and invasion of EC-ESCs and inhibits their apoptosis by targeting miR-216a-5p. These findings indicate potential therapeutic targets for endometriosis.

Silencing of circ_0007299 suppresses proliferation, migration, and invasiveness and promotes apoptosis of ectopic endometrial stromal cells in endometriosis via miR-424-5p-dependent modulation of CREB1

BACKGROUND

The abnormality of endometrial stromal cells (ESCs) can contribute to endometriosis pathogenesis. Circular RNAs (circRNAs) possess critical roles in endometriosis pathogenesis. Here, we defined the activity and mechanism of human circ_0007299 in the regulation of ectopic ESCs in vitro.

METHODS

Circ_0007299, miR-424-5p and cAMP response element-binding protein 1 (CREB1) were quantified by qRT-PCR or immunoblotting. Cell viability, proliferation, apoptosis, invasion and motility were gauged by CCK-8, 5-Ethynyl-2'-Deoxyuridine (EdU), flow cytometry, transwell, and wound-healing assays, respectively. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to verify the direct relationship between miR-424-5p and circ_0007299 or CREB1.

RESULTS

Our data showed that circ_0007299 was upregulated in human ectopic endometrium tissues and ectopic ESCs. Silencing endogenous circ_0007299 impeded the proliferation, invasiveness, and motility and enhanced apoptosis of ectopic ESCs. Mechanistically, circ_0007299 regulated miR-424-5p expression. Moreover, circ_0007299 silencing impeded the proliferation, invasiveness, and motility and enhanced apoptosis of ectopic ESCs via its regulation on miR-424-5p. CREB1 was identified as a direct miR-424-5p target, and miR-424-5p overexpression suppressed ectopic ESC proliferation, migration, and invasiveness and promoted apoptosis by downregulating CREB1. Furthermore, circ_0007299 positively modulated CREB1 expression through miR-424-5p competition.

CONCLUSION

Our findings establish that circ_0007299 silencing impedes the proliferation, invasiveness, and motility and promotes apoptosis of ectopic ESCs at least in part via miR-424-5p-dependent modulation of CREB1.

RNA-seq reveals co-dysregulated circular RNAs in the adenomyosis eutopic endometrium and endometrial–myometrial interface

Background

Uterine adenomyosis is associated with chronic pelvic pain, abnormal uterine bleeding, and infertility. The pathogenesis of adenomyosis is still unclear. Circular RNAs (circRNAs) have been implicated in several benign diseases and malignant tumors. We aimed to explore the co-dysregulated circular RNA profile in the eutopic endometrium and endometrial–myometrial interface (EMI) of adenomyosis.

Methods

Total RNA was extracted from the eutopic endometrium and EMI of 5 patients with adenomyosis and 3 patients without adenomyosis. Next-generation sequencing was performed to identify the circRNA expression profile of the two tissue types. Bioinformatics analysis was performed to predict circRNA-binding miRNAs and miRNA-binding mRNAs and construct ceRNA networks, and functional enrichment analysis was performed to predict the biological functions of circRNAs.

Results

Among the adenomyosis patients, 760 circRNAs were significantly upregulated and 119 circRNAs were significantly downregulated in the EMI of adenomyosis, while 47 circRNAs were significantly upregulated and 17 circRNAs were significantly downregulated in the eutopic endometrium of adenomyosis. We identified hsa_circ_0002144 and hsa_circ_0005806 as co-upregulated and hsa_circ_0079536 and hsa_circ_0024766 as co-downregulated in the eutopic endometrium and EMI. Bioinformatics analysis was performed to construct a ceRNA network of codifferentially expressed circRNAs. The MAPK signaling pathway is the most important signaling pathway involved in the function of the ceRNA network.

Conclusions

Co-dysregulated circRNAs were present in the eutopic endometrium and EMI of adenomyosis. MiRNA binding sites were observed for all of these circRNAs and found to regulate gene expression. Co-dysregulated circRNAs may induce the eutopic endometrial invagination process through the MAPK signaling pathway and promote the progression of adenomyosis.

The Critical Roles of Circular RNAs in Basic Research and Clinical Application of Female Reproductive-Related Diseases

Circular RNAs (circRNAs), produced by precursor mRNAs, are a type of covalently closed circular molecule without 5' caps and 3' polyadenylated tails. Recently, advances in high-throughput sequencing, transcriptomics and bioinformatics, have revealed that circRNAs with specific traits in tissue or cells play emerging roles in both physiological and panthological contexts instead of as simple by-products of transcription. However, bringing circRNAs to the forefront of clinical practice is still a long way off. In this review, we highlight the progress in the formation and function of circRNAs, and how circRNAs work in female reproductive-related diseases, such as recurrent spontaneous abortion, preeclampsia, and endometriosis. We also discussed the clinical potential of circRNAs as biomarkers, and therapeutic agents in female reproductive diseases as well as research controversies, technical issues, and biological knowledge gaps that need to be addressed. This review may instruct future basic research and clinical applications on circRNAs, especially in female reproduction.

RETRACTED: Overexpressed miR-106b-5p promotes epithelial-mesenchymal transition in endometriosis by targeting PTEN

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. The journal was contacted by the corresponding author to claim that they were not aware of the submission of the article, do not own the email address listed by the paper, and did not participate in the study. When contacted by the journal, the co-authors Shan Liu and Haiying Ren also denied that they participated in the study and that they were aware of the article. The co-authors Fen Hu, Yonglian Wang and Xueqing Wu did not respond to the journal's request for clarifications. The uncertainty about the identity of the author who submitted the article also cast doubt on the data and the Editor decided to retract the paper.

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.

[Lowered expression of CCN5 in endometriotic tissues promotes proliferation, migration and invasion of endometrial stromal cells]

OBJECTIVE

To explore the expression of CCN5 in endometriotic tissues and its impact on proliferation, migration and invasion of human endometrial stromal cells (HESCs).

METHODS

We collected ovarian endometriosis samples from 20 women receiving laparoscopic surgery and eutopic endometrium samples from 15 women undergoing IVF-ET for comparison of CCN5 expression. Cultured HESCs were transfected with a recombinant adenovirus Ad-CCN5 for CCN5 overexpression or with a CCN5-specific siRNA for knocking down CCN5 expression, and the changes of cell proliferation, migration and invasion were evaluated using CCK-8 assay, wound healing assay and Transwell chamber assay. RT-qPCR and Western blotting were used to examine the expression levels of epithelial-mesenchymal transition (EMT) markers including E-cadherin, N-cadherin, Snail-1 and vimentin in HESCs with CCN5 overexpression or knockdown.

RESULTS

CCN5 expression was significantly decreased in ovarian endometriosis tissues as compared with eutopic endometrium samples (P < 0.01). CCN5 overexpression obviously inhibited the proliferation, migration and invasion of HESCs, significantly increased the expression of E-cadherin and decreased the expressions of N-cadherin, Snail-1 and vimentin (P < 0.01). CCN5 knockdown significantly enhanced the proliferation, migration and invasion of HESCs and produced opposite effects on the expressions of E-cadherin, N-cadherin, Snail-1 and vimentin (P < 0.01).

CONCLUSION

CCN5 can regulate the proliferation, migration and invasion of HESCs and thus plays an important role in EMT of HESCs, suggesting the potential of CCN5 as a therapeutic target for endometriosis.

Circular RNA PIP5K1A (circPIP5K1A) accelerates endometriosis progression by regulating the miR-153-3p/Thymosin Beta-4 X-Linked (TMSB4X) pathway

As a common gynecologic disease, endometriosis (EM) poses a threat to the reproductive health of about 10% women globally. Recent studies have revealed that circular RNAs (circRNAs) are deeply implicated in EM pathogenesis. However, the functions of circPIP5K1A in EM have not been studied yet. Our study intended to uncover the molecular mechanism of circPIP5K1A in EM. In this work, gene and protein expressions were determined by RT-qPCR or Western blotting. CCK-8, wound healing, transwell, and flow cytometry assays were conducted to analyze cell viability, migration, invasion, cell cycle, and apoptosis. Additionally, bioinformatics analysis, dual-luciferase reporter assay, as well as RIP assay were performed to investigate the combination between miR-153-3p and circPIP5K1A or TMSB4X. Herein, we found remarkable high circPIP5K1A expression in EM tissues and cells. Silencing of circPIP5K1A suppressed proliferation, restrained cell cycle, increased cell apoptosis, and decreased migration and invasion in EM cells. In addition, miR-153-3p inhibition could abrogate the impacts of circPIP5K1A knockdown on EM progression in vitro. Also, we found that circPIP5K1A regulated TMSB4X level via interaction with miR-153-3p in EM cells. Besides, circPIP5K1A promoted EM progression via TMSB4X. Moreover, TMSB4X could activate the TGF-β signaling in hEM15A cells. To sum up, our study elucidated that circPIP5K1A accelerated EM progression in vitro by activating the TGF-β signaling pathway via the miR-153-3p/TMSB4X axis, providing a potential clinical target for EM treatment.

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.